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Comparative study of Li-ion battery recycling processes September 2020 , Page 2 Comparative study of Li-ion battery recycling processes Reiner Sojka* , Qiaoyan Pan, Laura Billmann ACCUREC Recycling GmbH Bataverstrasse 21 | DE - 47809 Krefeld, Germany Keywords: Executive, Germany Summary Li-ion battery recycling, LIB mechanical treatment, LIB thermal treatment This study provides a comprehensive review of Li-ion battery (LIB) recycling technologies. In the study, we outline and evaluate the current existing industrial LIB recycling processes globally as well as novel lab-scale initiatives. We briefly introduce the LIB components and their possible reactions during battery handling, in order to substantiate the technical requirements for recycling plant specification and process management. Secondly, we give a brief introduction of LIB recycling technologies and an overview of current LIB recyclers in the world. Thirdly, we further introduce the industrial recyclers, giving more detailed information about the companies, their LIB recycling technologies, treatment capacity, etc. Afterwards, several representative examples lab of novel -scale LIB recycling technologies are described, in order to integrate the latest development. Finally, we evaluate and compare these recycling technologies comprehensively from technical, economic and environmental performances points of view. Main conclusions from the study can be drawn as follows: 1) The LIB materials and their reactions generate environmentally hazardous, human-toxic, highly corrosive substances (e.g. HF), as well as explosive gas mixtures, which must be considered to design a safe LIB tt process. 2) After investigating current industrial available LIB recycling technologies, we can structure them into four different process steps, namely Preparation, Pretreatment (including thermal and mechanical Pretreatment), Pyrometal lurgy and Hydrometallurgy, which can be combined in six different possible sequences. What they all have in common is that the material has to undergo the final necessary hydrometallurgical refining, to obtain tradeable products. 3) Currently only two of the combinations, both of which involve thermal Pre treatment and Pyrometallurgy, have proven their technical feasibility and industrial maturity. Economic evaluation shows that these two process routes exhibit overall advantages. 4) In contrast, those process routes without these two steps (e.g. mechanical pretreatment + hydrometallurgy) show technical-economic disadvantages, because, for example, the formed corrosive gases increase maintenance cost in Pretreatment step and the highly contaminated intermediate products require additional effort and cost for impurity removal in the final hydrometal lurgical refining step, which indicates the reason why they haven't been up scaled to mature industrial technologies yet. Comparative study of Li-ion battery recycling processes Reiner Sojka" , Qiaoyan Pan, Laura Billmann ACCUREC Recycling GmbH September 2020 , Page 3 5) Many novel lab-scale LIB recycling technologies are being developed in order to increase recycling rate and/or to lower the cost, including a so-called Direct Re cycling Process, in which cathode or anode materials are separated, recondi tioned and then directly re-used for manufacturing LIB, instead of undergoing pyro- and hydrometallurgy. However, the commercialization feasibility of those lab-scale technologies still needs to be proved. Considering unproved product quality, "Direct Recycling Process" and usage of separated AM for battery mate rial precursor seem to be unrealistic. List of abbreviations AM DEC DMC EC EMC EOL EV GHS ISC LCO LFP LFL LIB LMO LTO NCA NMC PC SEI SME UFL Active Mass (Powder) Di Ethyl Carbonate Di Methyl Carbonate Ethylene Carbonate Ethyl Methyl Carbonate End of Life Electric Vehicle Globally Harmonized System of Classification and Labelling of Chemicals Internal Short Circuit Lithium Cobalt Oxide, LiCoO2 Lithium Iron Phosphate, LiFePO4 Lower Flammability Limit Li-ion Battery Lithium Manganese Oxide, LiMn2O4 Lithium Titanium Oxide, Li4Ti5O12 Lithium Nickel Cobalt Aluminum oxide, LiNixCoyAlzO2 Lithium Nickel Manganese Cobalt Oxide, LiNixMnyCozO2 Propylene Carbonate Solid-Electrolyte Interphase Small and Medium-Sized Enterprises Upper Flammability Limit Corresponding author, Email: Eaccurec.de Comparative study of Li-ion battery recycling processes Reiner Sojka* , Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 4 Table of contents 1. Introduction 6 2. Li-ion batteries: structure, material properties and safety-related considerations 6 2.1 Li-ion battery structure and material characteristics 6 2.2 Malfunction and reactions of Li-ion batteries 9 2.2.1 Thermal Runaway: mechanism, causes and influencing factors 10 2.2.2 Toxic gas emissions from Li-ion battery 12 3. General overview of Li-ion recycling technologies and recyclers 15 3.1 General overview of Li-ion recycling technologies 15 3.1.1 Preparation 15 3.1.2 Pretreatment 15 3.1.3 Main treatment: pyrometallurgy (intermediate purification) 15 3.1.4 Main treatment: hydrometallurgy 16 3.2 General overview of current LIB recyclers in the world 18 4. Industrial-scale (>1000t/a) Li-ion battery recycling processors 20 4.1 Processors within EU 20 4.1.1 Umicore (Belgium) [Pyro + Hydro] 20 4.1.2 Accurec (Germany) [Thermal + Mechanical + Pyro + Hydro] 22 4.1.3 Nickelhtte Aue (Germany) [Thermal + Pyro + Hydro] 24 4.2 Processors outside EU 25 4.2.1 SungEel HiTech (South Korea) [Mechanical + (Thermal +) Hydro] 25 4.2.2 Kyoei Seiko (Japan) [Pyro] 25 4.2.3 Dowa (Japan) [Thermal + Pyro + Hydro] 26 4.2.4 Brunp (China) [Thermal + Mechanical + Hydro] 27 4.2.5 GEM (China) [Mechanical + Hydro] 28 4.2.6 Huayou Cobalt (China) [Mechanical + Hydro] 29 4.2.7 Ganzhou Highpower (China) [Mechanical + Pyro + Hydro] 29 5. Pilot-scale (<1000 t/a) Li-ion battery recycling processors 30 5.1 Processors within EU 30 5.1.1 SNAM (France) [Thermal + Pyro + Hydro] 30 5.1.2 EDI (France) [Mech (aqueous shred) + unknown] 30 5.1.3 AkkuSer (Finland) [Mechanical + Hydro] 31 5.1.4 Redux (Germany) [Thermal + Mechanical + unknown] 31 Comparative study of Li-ion battery recycling processes Reiner Sojka* , Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 5 5.1.5 Duesenfeld (Germany) [Mechanical + Hydro] 32 5.1.6 Promesa (Germany) [Mechanical (aqueous shred) + unknown] 33 5.1.7 TES-AMM (formerly: Recupyl) (France) [Mechanical (inert gas)] 33 5.2 Processors outside EU 34 5.2.1 Retriev (US) [Mechanical (aqueous shred) + Hydro] 34 5.2.2 Kobar (Korea) [Mechanical + Hydro] 34 5.2.3 JX Nippon (Japan) [Thermal + Mechanical + Hydro] 35 5.2.4 Telerecycle (China) [Mechanical + Hydro] 36 5.2.5 Guanghua (China) [Mechanical + Hydro] 37 6. Lab-scale novel Li-ion battery recycling technologies 38 6.1 Mechanical separation and reconditioning for direct reuse 38 ("Direct Recycling") 6.2 Liquid/Supercritical CO2 for electrolyte extraction 39 6.3 Froth flotation for separating active mass 40 6.4 Electrohydraulic Fragmentation using shock waves 41 6.5 Sulphate roasting of active mass for early stage lithium extraction 43 7. Evaluation of various Li-ion battery recycling processes 44 8. Summary 49 9. References 50 Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 6 1. Introduction In recent years, Lithium-ion batteries (LIBs) are undergoing unprecedented development, especially driven by the development of electric vehicles (EVs) and renewable energy technologies. Accordingly, it is foreseeable that the amount of spent lithium-ion batteries will also increase dramatically in the next few years. However, LIB materials are intrinsically environmentally hazardous (e.g. flammable components, hazardous decomposition products) and present a safety risks (e.g. Thermal-Runaway behavior), leading to a serious waste-management challenge. On the other hand, spent batteries also present an opportunity to gain valuable resources as they contain numerous valuable materials, e.g. lithium, nickel and the EU critical raw material Cobalt. Therefore, the recycling of Li-ion batteries has attracted great attention in view of conservation of valuable resources, environmental and ecological impacts. 2. Li-ion batteries: structure, material properties and safety-related considerations 2.1 Li-ion battery structure and material characteristics A lithium-ion battery (LIB) is an advanced type of rechargeable batteries. Inside the batteries, lithium ions move from the negative electrode through an electrolyte to the positive electrode during discharge, and back when charging. Today, the negative electrode of a commercial lithium-ion cell is usually made from graphite. The positive electrode is a lithium metal oxide, for example, LiCoO2 (LCO), LiNixMnyCozO2 (NMC), LiMn2O4 (LMO) or LiFePO4 (LFP), and the electrolyte is a lithium salt (e.g. LiPF6) dissolved in organic solvents (e.g. PC, EC, DMC, DEC). Exemplary cell components and their mass fractions are demonstrated in Table 1 [1]. Table 1: Exemplary commercial Li-ion battery cell composition, adopted from [1]. Battery component Housing Cathode (positive electrode) Anode (negative electrode) Electrolyte Cathode current collector foil Anode current collector foil Separator Others (additives) Materials Steel or Al LCO, NMC, NCA, LFP or LMO Graphite LiPF6 dissolved in PC, EC, DMC or DEC Aluminum Copper PP, PE Carbon black, silicon, etc. Mass-% 20-25 25-35 14-19 10-15 5-7 5-9 1-4 Balance LIB can be constructed as cylindrical, prismatic or pouch cell for the whole range of applications. Exemplary cell constructions are shown as in Figure 1 [2] [3]. Most commercial, cylindrical lithium-ion cell design (18650) are equipped with a positive thermal coefficient (PTC) current limiting switch in the top cap, whose resistance will rise when large current runs through it, to protect the cell from external short circuits [4]. However, for prismatic and pouch cells there is no such short circuit protection device equipped in the cell. Therefore, for those cells, usually additional external devices such as electronic components need to be available for short circuit protection. September 2020 , Page 7 Figure 1: Constructional design of Li-ion cells (left: cylindrical, right: pouch) [2][3]. It is noted that the materials of LIB are more complex than that of previous battery systems (lead acid, NiCd, NiMH, Alkaline, etc.). For example, the electrochemical reactions of anode and cathode material are relatively simple in NiCd or lead batteries, and their water-based electrolyte makes them insensitive to thermal or mechanical abuse. Ingredients could therefore only have a chronic eco- or human-toxic effect. In contrast, LIB contains volatile, flammable organic electrolytes and fine solid particles (graphite and metal oxide), whose leakage or exposure is related to risks of fire and pollution. Environmentally related properties of materials used in commercial LIB are summarized in Table 2 and flammability limits as well as flash points of LIB electrolytes are summarized in Table 3. As seen from the tables, the ingredients can pose various types of hazards, in particular - Fire and explosion hazard due to high calorific, highly volatile and self-igniting carbonate electrolytes, - Human toxic effects due to gaseous, sometimes lethal decomposition products (e.g. HF, benzene, etc.) from battery components. - carcinogenic effect through release of inhalable particles of Ni/Co/Mn compounds (<10 m), Those potential hazards should be considered in handling of waste Li-ion batteries. Additionally, under certain circumstances (e.g. overcharged, external/internal short-circuit, overheat, etc.), a so-called ``thermal runaway'' behavior can be triggered, releasing rapidly massive heat and toxic off-gases, bringing technical hazards and health risks. This will be discussed in more details in next sub-chapter. Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 8 Table 2: Environmentally related properties of materials used in commercial LIB [9] Materials Ethylene carbonate (EC, C3H4O3) Properties Vapor pressure: 21 Pa (20 C). Toxicity and hazard to water: - Causes serious eye irritation - slightly hazardous to water (German water hazard class: WGK 1*) Propylene carbonate (PC, C4H6O3) Dimethyl carbonate (DMC, C3H6O3) Diethyl carbonate (DEC, C5H10O3) Ethyl methyl carbonate (EMC, C4H8O3) Lithium hexafluorophosphate (LiPF6) Vapor pressure: 4 Pa (20 C), 130 Pa (50 C). Toxicity and hazard to water: - Causes serious eye irritation - slightly hazardous to water (German water hazard class: WGK 1) highly flammable, highly volatile Vapor pressure: 5300 Pa (20 C). Toxicity and hazard to water: - irritant effects, nausea, intoxication, unconscious-ness, respiratory stop - slightly hazardous to water (German water hazard class: WGK 1) highly flammable, highly volatile Vapor pressure: 1100 Pa (20 C). Toxicity and hazard to water: - low toxicity - slightly hazardous to water (German water hazard class: WGK 1) highly flammable, highly volatile Vapor pressure: 3600 Pa (25 C). Toxicity and hazard to water: - irritant - slightly hazardous to water (German water hazard class: WGK 1) Toxicity and hazard to water: - causes severe skin burns and eye damage - highly hazardous to water (German water hazard class: WGK 3) Lithium cobalt dioxide (LiCoO2) Lithium-nickel-manganese-cobalt oxide Li(NixCoyMnzO2) At high temperatures, exothermic decomposition reaction with release of oxygen Toxicity and hazard to water: - irritant, hazardous to health - Cobalt salts can lead to cardiomyopathy (heart muscle disease) - possibly carcinogenic Toxicity and hazard to water: - toxic, Co, Ni in the compound - Hazard to water: no information Lithium - Titanate (Li4Ti5O12) Toxicity and hazard to water: - slightly irritating to the respiratory tract - Nanocrystals can be toxic due to their small size September 2020 , Page 9 * About WGK: The foundation for the classification are scientific tests on the respective substance. [...] How the data is to be collected is specified in Regulation (EG) No. 440/2008 on the definition of test methods (with corresponding regulations to amend them). If hazard statements according to Regulation (EC) No. 1272/2008 (CLP Regulation) have been derived for the respective substance from these scientific tests, these hazard statements are assigned corresponding assessment points. The more toxic a substance is, the more points are assigned. The basic data set consists of the four hazard characteristics: i. Acute oral or dermal mammalian toxicity ii. Acute aquatic toxicity iii. Biodegradability iv. Bioaccumulation potential" Source https://www.umweltbundesamt.de/wgk-einstufung There are 3 Classes of these classification system the higher the number the higher the thread to stretches of water and the inside living fauna and flora. For Further information please read Regulation 2000/60/EG, 2006/123/EG, 91/676/EWG. Table 3: Lower/Upper Flammability Limit (LFL/UFL) and flash point of Li-ion battery electrolytes Electrolyte EC DMC EMC DEC PC EA DE THF Name Ethylene carbonate Dimethyl carbonate Ethyl methyl carbonate Diethyl carbonate Propylene carbonate Ethyl acetate Diethyl ether Tetrahydrofuran AN Acetonitrile DME Ethylen glycol dimethylether DMSO Dimethyl sulfoxide g-GBL g-Butyrolactone Chemical formula C3H4O3 C3H6O3 C4H8O3 C5H10O3 C4H6O3 C4H8O2 C4H10O C4H8O LFL, %vol (in air) 3,6 4,22 2 1,4 1,7 2,2 2 1,5 UFL, %vol (in air) 16,1 12,87 N.A. N.A. 21 9 36 12 Flash point, C 143 18 23 33 123 -4 -45 -17 C2H3N 3 16 2 C4H10O2 1,6 10,4 5 C2H6OS 2,6 42 89 C4H6O2 3,6 16 98 2.2 Malfunction and reactions of Li-ion batteries In order to be able to assess the battery behavior and its effects in recycling activities, it is necessary to take a closer look at the malfunctioning and reactions of LIB. It is irrelevant whether the cell is mechanically or thermally damaged - reactions of the ingredients will occur. In the case of (partially) charged batteries, this happens mainly through the mechanism of a so-called Thermal Runaway, but also in discharged batteries relevant reactions take place. In addition, the ingredients inevitably react with the substances in the surrounding environment (e.g. LiPF6 reacts with H2O). Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 10 2.2.1 Thermal Runaway: mechanism, causes and influencing factors An increasing number of fire incidents during using, storing or treating LIB are reported and they are attributed to the self-ignition by Thermal Runaway (TR). The TR is self-reinforcing, continuous, exothermic chemical reactions that can be triggered by faults or damage in a LiB, leading to heating and final spontaneous ignition (as shown in Figure 2 [5]). Figure 2: Accidents related with lithium ion battery failure, and correlated abuse conditions [5]. Figure 3 shows an example of surface temperature development of a LIB (NCM) undergoing Thermal Runaway [6]. The development undergoes several stages, accompanying with nu-merous temperature-dependent reactions. Once the TR is triggered, the reactions proceed very quickly and cannot be interrupted from the outside and it ends within seconds with a complete destruction of the battery cell. Moreover, the TR of one cell can propagate to the surrounding cells or other materials, leading to "Chain Reaction" and thus escalate the fire. The features of TR are: 1) Reacts very fast (from start to peak, only ca.20 seconds) 2) Releasing massive heat 3) Releasing large volume of toxic gases Figure 3: Example of surface temperature evolution at LIB Thermal Runaway [6] September 2020 , Page 11 The intrinsic heat source for Li-ion battery's thermal runaway is associated with electrical energy and chemical energy. The electrical energy can be evaluated by the battery rated capacity and the state of charge (SOC) of the battery, while the chemical energy is a material issue (related to decomposition / interaction of materials). In other words, the chemical energy mainly depends on the properties of the substances used in the battery. A schematic diagram of energy release of Li-ion battery is shown in Figure 4 [5]. Under various temperatures different reactions of materials occur. More details about the overall reactions can be found in paper [5] and [7]. It is worthy to pay special attention to the decomposition reaction of cathode material (under charged state), which releases O2 gas and leads to more exothermic reactions (see exemplary reactions below [5]). On one hand, the generated O2 can react with organic electrolytes (as combustion reaction), releasing massive heat [5]. On the other hand, it is reported in [8], the generated O2 can also reacts with reductive anode material (LiCx), contributing to even more heat generation. Li0.5CoO2 -- 1/2 LiCoO2 + 1/6 Co3O4 + 1/6 O2 (1) Li0.36Ni0.8Co0.15Al0.05O2 -- 0.18 Li2O + 0.8 NiO + 0.05 Co3O4 + 0.025 Al2O3 + 0.372 O2 (2) Li0.35(NiCoMn)1/3O2 -- Li0.35(NiCoMn)1/3O2-y + y/2 O2 (3) 2.5 O2 + C3H4O3(EC) -- 3 CO2 + 2 H2O (4) Figure 4: Schematic diagram of the energy release of lithium ion battery [5]. Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 12 The thermal runaway of the LIB cell can be attributed to different causes as follows [5][9]: - External short circuit, - Overcharge, - Over-discharge, - Internal short circuit (due to cell failure or abuses), is the most common feature for all abuse conditions, - Overheating due to external heating, - External mechanical damage to the cell (leading to internal short circuit). The course (reaction kinetics) and the intensity (amount of energy, temperature level) of the TR depends on the following boundary conditions: - State of Charge (SOC): Most violent at 100% SOC or >100% SOC (overcharge) due to max. electric Energy, - Ambient temperature, - Cell chemistry (LCA/LCO/NMC/LMO/LFP): LFP is less reactive, - Construction of the cell (cell size, electrolyte volume etc.). The spread of TR of one cell to neighboring cells in the sense of a chain reaction is dependent on the - type of contact of cells and distance to the neighbouring cell, - Type of insulation material used between the packed LIB (low thermal diffusivity [m2/s] material is good for packaging and storage of LIB [10]), - the type and extent of exposure to hot gases from pressure release or combustion gases after self-ignition. 2.2.2 Toxic gas emissions from Li-ion battery As a result of the self-destruction of the battery cell, gas mixtures are formed whose composition depends on the battery subtype, state of charge and ambient atmosphere. Table 4 summarizes the emitted gases from various LIB sub-chemistries, tested under various abuse conditions and various atmospheres [7]. It can be seen that under all different conditions, no matter thermally or mechanically treated, no matter in air or in inert gas (Ar, N2), unneglectable amount of toxic gases is generated. It is important to note that, toxic fluoride gases (e.g. HF and/or POF3) are generated both in thermal treatment (namely, heating, fire or combustion) and in mechanical treatment (penetration test) [7] [11]. As a consequence, off-gas cleaning system is not only needed in thermal treatment, also in mechanical treatment an extensive off-gas cleaning system is mandatory. The fluoride gases mainly come from the decomposition reaction of electrolyte LiPF6, which is promoted by the presence of water/humidity according to the following reactions [11]: LiPF6 -- LiF + PF5 (5) PF5 +H2O -- POF3+2HF (6) LiPF6 +H2O -- LiF + POF3 +2HF (7) September 2020 , Page 13 Table 4: Summary of emission gases from LIB (adopted from [7]), yellow underlined: off-gas from mechanical treatment References Campion et al. (2004) Ohsaki et al. (2005) Abraham et al. (2006) Onuki et al. (2008) Ribire et al. (2012) Wang et al. (2012) Chanson (2013) Ponchaut et al. (2014) Material Test Condition Off-gas Cathode Type Method LCO NCA NCA LMO 633,048 18650 Pouch Pouch Heating Overcharge Vent/ Penetration Heating Combustion Atm. Electrolyte Ar Air LCO n. a. TR Li-ion n. a. TR LCO Pouch TR Ar CO2 CO H2 CxHy HF Other Test equipment x x x xx x x xx x x xx x x x x xx x x xx x x xx x Fluoride GC-MS, NMR GC C2HF GC-MS x HCN NOx SOx HCl x C2H5F x GC/AED FTIR, FDI, paramagnetic analyzer FTIR, GC-MS, NMR n. a. GC-MS Larsson et al. (2014b) LFP Pouch Propane fire Air LCO 633,048 Overcharge x x x x x POF3 FTIR GC Golubkov et al. (2015) Lecocq et al. (2016) Sun et al. (2016) NMC 18650 Heating Ar LFP LFP Pouch Combustion Air Li-ion Both Combustion Air Kwade et al. (2016) NCM Pouch Penetration N2 x x x x x x x x xx x x x GC SO2 NDIR, FTIR, FID x SO2 COS GC-MS, IC CxHyNz C5H9NO x FTIR NCM 18650 Penetration N2 x x x x x NCA 18650 Penetration N2 x x x x x Nedjalkow et al. (2016) NMC Pouch Penetration Air x Warner (2017) n. a. Heating Air Diaz et al. (2019) [7] & Bartosinski, et al (2017) [12] LCO, NCM LFP 18650 and pouch Pyrolysis, combustion, penetration Air or x N2 x x x x x x ClO2 GC-MS, QMS, SO2 QEPAS, IC Accrlein, COS x x HCl, FTIR HCN, SO, H2S x Accrolein FTIR, IC (C3H4O) COF2 HCl Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 14 Table 5: Toxicological evaluation of gases released from LIB [13] Reaction product Benzene (C6H6) Properties according to GHS H225 H304 H315 H319 H340 H350 H372 H412 Single lethal dose of benzene for humans: 125 mg/kg (= 10 ml/70 kg) Styrenics (C8H8) H226, H315, H319, H332, H372, H361d Ingestion: LC50, for rats: 5000 mg/kg, in mice: 316 mg/kg Hydrofluoric acid (HF) Hydrochloric acid (HCl) H300, H310, H330, H314, H318 lethal dose: 20 mg/kg body weight. (A ton of LIB cells can release 1.0 - 6.6 kg HF, according to Accurec's off-gas measurement and calculation [12]) H300, H310, H330, H314, H318 30-min LC50, in rats: 4700 ppm, in mice: 2600 ppm Carbon monoxide (CO) H220, H331, H372, H360d 30-min LC50, in humans: 3000 ppm But not only the emission of gases can cause enormous problems. The energy release, for example, up to 22,000 MJ/t in the case of standard household LiB packs, is also often underestimated in process control and in the event of fire. In conclusion, it can be said that in all parts of the reverse chain, i.e. the intermediate storage, collection and recycling process, significant material and environmental risks arise from spon-taneous combustion, chain reactions and the possible release of eco- and human-toxic gases, regardless of the SOC of the battery. Therefore, great attention has to be paid considering safety and emission issues during storage and recycling of LIB. September 2020 , Page 15 3. General overview of Li-ion recycling technologies and recyclers 3.1 General overview of Li-ion recycling technologies The processing of complex waste such as a Li-ion battery requires a multi-stage process chain. With the growing demands on the variety and quality of the output products, the number of treatment stages increases proportionally. Conversely, a simple, undifferentiated treatment (e.g. direct melting) would produce an equally undifferentiated, mixed product with a high number of elements at low level evaluation. If one tries to categorize and schematize the Li-ion battery recyclers with their applied techniques, this can be illustrated with the simplified flowchart in Figure 5. They can be divided into - Optional preparation before recycling, including sorting, disassembly, discharging, etc. - Multi-step pretreatment in dedicated battery recycling plants, these are companies spe-cializing in battery pretreatment, commonly medium-sized companies, - Multi-step main-processing in (mostly) non-dedicated battery recycling plants. 3.1.1 Preparation Upstream preparation processes are not directly assigned to the recycling process because they are not directly involved in the recovery of the ingredients and do not change the condition or composition of the LIB cell. Classically, this includes the dismantling of large stationary or automotive battery packs to cell or module size or sorting by subtype, separation of plastic housings (common household power packs) and/or discharging. 3.1.2 Pretreatment Different from the preparation processes, the components are chemically and/or physically changed during the Pretreatment of Li-ion cells. It only serves the goal of separating or changing the battery ingredients to such an extent that they can be fed into existing, large-scale industrial routes. While in the 2000s a negligible amount of end-of-life LIB (EOL-LIB) was still untreated and heavily diluted in industrial routes, today its volume in the EU (> 10.000 t/a) can no longer be disposed of in this way without disruptive effects. If left untreated on this large scale, they would cause operational disruptions, e.g. in converters or smelters by: - Fire and explosion events in feeding systems (TR), - Input of impurities due to incorrect sorting (Pb, Cd, Hg etc.) and - Gas explosions in smelters due to spontaneous evaporation and reaction of organic components (especially volatile electrolytes) and/or water components. A pretreatment can be merely mechanical or thermal treatment, or a combination of both. 3.1.3 Main treatment: pyrometallurgy Following pretreatment, the battery residues should be subjected to a pyrometallurgical intermediate purification in order to be able to supply them to a hydrometallurgical final refining pro-cess. This pyrometallurgy serves to remove unwanted or process disturbing components and to convert the target components into a uniform intermediate product. In particular, it can compensate the fluctuations in the composition of the feedstock, to which hydrometallurgical processes are extremely sensitive. Battery components such as fluorine, chlorine, graphite, phosphorus etc. are essentially technically disturbing in hydrometallurgy. However, they can be slagged or used in the pyrometallurgical step (e.g. graphite used as a reducing agent) and thus re- Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 16 moved. It also makes economic sense here to slag low-value, non-precious metals such as iron, manganese or aluminium residues, which would cause high material and energy costs through dissolving, precipitation and filtering in the hydrometallurgy. 3.1.4 Main treatment: hydrometallurgy The highly complex hydrometallurgical refining step usually consists of an autoclave, (chlo-rine) acid leaching of the intermediate product from pyrometallurgical treatment, precipitation and filtering of non-noble metals or undesirable elements, followed by solvent extraction and nickel electrowinning, ion exchange and cobalt electrowinning. Further roasting, dissolving, precipitation, filtering and electro-extraction processes take place in parallel and sequentially on side routes to extract copper and other by-metals such as lead, precious metals, etc. An economic recovery of the most important LIB valuable components, which so far and certainly in the medium term still concentrate on Co/Ni/Cu, is therefore only possible after a detailed pretreatment and pyrometallurgical intermediate purification in order to finally return them as products into the economic cycle. September 2020 , Page 17 Figure 5: Overview about schematized Li-ion batteries recycling routes Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 18 3.2 General overview of current LIB recyclers in the world In Table 6 an overview of current LIB recyclers in the world is given. It is noted that we introduce the main players on the market, but not all world-wide companies are listed. Especially for the market outside EU, accessible information is limited. Therefore, some companies out-side EU could be missing in the list. Also, in recent years many companies announced to start LIB recycling business, but by now (2020) they have not started pilot or industrial operation yet (i.e. still under planning or under construction). Those companies are also not listed. We categorize the recyclers into three different scales according to their current treatment capacity: - Industrial scale: > 1000 t/a - Pilot scale: < 1000 t/a (e.g. a few hundred tons/a) - Lab-scale: small-scale trials (some grams or kilograms), or sometimes pilot-scale trials (some hun- dred kilograms or more) but not commercialized yet. Table 6: Current worldwide LIB recycling companies and their recycling technologies Scale Industrial scale (>1000 t/a) Pilot scale (<1000 t/a) Lab scale Inside EU Umicore (BE) Accurec (DE) Nickelhtte Aue (DE) SNAM (FR) EDI (FR) TES-AMM (formerly "Recupyl") (FR) AkkuSer (FI) Duesenfeld (DE) Promesa (DE) Redux (DE) Erlos (DE) Info. reliability* Pyro + Hydro Thermal + Mech + Pyro + Hydro Thermal + Pyro + Hydro Thermal + Pyro + Hydro Mech (aqueous shred + unknown) Mech (inert gas) Mech + unknown Mech + Hydro Mech (aqueous shred) + unknown Thermal + Mech + unknown Mech + reconditioning (direct recycling) (Green: Detailed info. confirmed by various sources) (Red: limited info. available, only official source from the company) (Orange: Further info. available, but still limited) September 2020 , Page 19 Industrial scale (>1000 t/a) Pilot scale (<1000 t/a) Outside EU SungEel (KR) Kyoei Seiko (JP) Dowa (JP) Brunp (CN) GEM (CN) Huayou Cobalt (CN) Ganzhou Highpower (CN) Retriev (US) Kobar (KR) JX Nippon (JP) Telerecycle (CN) Guanghua (CN) Mech + (thermal +) Hydro Pyro Thermal + Pyro + Hydro Thermal + Mech + Hydro Mech + Hydro Mech + Hydro Mech + Pyro + Hydro Mech (aqueous) + Hydro Mech+ Hydro Thermal + Mech + Hydro Mech + Hydro Mech + Hydro (Green: Detailed info. confirmed by various sources) (Red: limited info. available, only official source from the company) (Orange: Further info. available, but still limited) * Notes: - Thermal: Thermal pretreatment. Mech: Mechanical treatment. Pyro: Pyrometallurgy. Hydro: Hy-drometallurgy. - The process steps do not represent necessarily the inhouse operation in the company. Opera-tions could be conducted by external partners. - *Info of Asian recyclers are limited/not easily accessed. Their capacities are estimated by the authors. There could be more production scrap rather than End-of-Life batteries as input material. Additionally, their processes were mostly built in recent years, although they are large in scale, the technical maturity may have not been proved. Their choice of technologies may also be affected by local policies, besides technical and economic considerations (For example, the company could choose mechanical pre-treatment instead of ther mal-pretreatment due to limited permit of incinera-tor operation). More information about the recyclers and their recycling technologies will be described in following chapters. Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 20 4. Industrial-scale (>1000t/a) Li-ion battery recycling processors This chapter will demonstrate the industrial-scale (>1000 t/a) LIB recycling processors within EU and outside EU, including the company background, LIB recycling capacity, technologies, etc. 4.1 Processors within EU 4.1.1 Umicore (Belgium) - [Pyro + Hydro] Umicore N.V. is a multinational material processing group headquartered in Brussels, Belgium. It has relatively wide business divisions, including Energy Materials, Performance Materials, Catalysis, and Recycling. In 2011, a battery recycling pilot plant has been tested in Hofers, Sweden and later was upscaled and installed in Hoboken, Belgium (known as subsidiary Umicore Battery Recycling H.Q.). A permitted capacity of 7000 t/a for Li-ion batteries has been announced in the Hoboken plant [14]. The current treatment capacity is unknown. The Umicore process is mainly composed of smelting (in shaft furnace) and subsequent hydrometallurgical treatment steps (see flowchart in Figure 6) [15]. Li-ion and NiMH batteries and production scraps are fed directly without significant preparation treatment into the smelter. Preparation is limited to large sized industrial batteries, which are first dismantled to small size (e.g. cell level). Besides batteries, additives such as coke, sand and limestone (slag for-mers) are fed into the smelting furnace. Figure 6: Li-ion & NiMH battery recycling process published by Umicore [15] September 2020 , Page 21 More details about the smelting process in the shaft furnace can be schematically shown in Figure 7 [16]. Based on the reactions occurring as a result of the gradual temperature increase in the process, the smelter can be divided into three zones: 1) upper zone (<300C), where electrolytes are evaporated, 2) middle zone (700C), where plastics are pyrolyzed and 3) bottom zone (1200-1450C), where smelting and reduction happen [16] [17]. Figure 7: Schematic diagram of Umicore's shaft furnace [16] The organics (electrolyte solvents and plastic housings) and graphite, which account for appr. 25-50 wt% (depending on battery packs' construction) of batteries, are used as combustible compounds and reducing agent for metal oxides. It is said that the energy released during these reduction reactions provides sufficient energy to heat up the smelter. A gas cleaning system ("UHT technology") has been installed, in order to fully decompose the organic compounds and ensure that no harmful dioxins or volatile organic compounds (VOC's) are produced [14]. Fluorine is captured in the flue dust. Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 22 To summarize, the smelter generates following output fractions [14]: Metal alloy: Containing Co, Ni, Cu, Fe, which can be forwarded to the downstream hydro-metallurgical process for recovery of Co, Ni and Cu. It is noted that since hydrometallurgical process requires fine par ticle as input material (especially in leaching step), the alloy shall be granulated before forwarding them into leaching step in hydrometallurgical process. Slag: Containing Al, Li, Mn, which can be used in the construction industry or further processed for metal recovery. The slag from Li-ion batteries is said to be integrated in Li-recovery flowsheets through a cooper ation with external partners. Cleaned gas: Off-gas is cleaned by UHT technology. The flue dust resulting from cleaning system, which contains the halogens (mainly F), is landfilled. 4.1.2 Accurec (Germany) - [Thermal + Mechanical + Pyro + Hydro] Accurec Recycling GmbH, founded in 1995, is a dedicated battery recycling company based in Germany for all kind of modern rechargeable batteries. Concerning Li-ion batteries, both portable and industrial applications, including automotive batteries, can be recycled at Accurec. In 2016, Accurec opened a new Li-ion dedicated recycling center in Krefeld, Germany. In 2019, Accurec has reached treatment capacity of 3000 t/a of Li-ion batteries. Following above-mentioned categories, Accurec recycles Li-ion batteries through thermal pretreatment and mechanical separation (see Figure 8). Before this, batteries are prepared, including sorting, disassembly and discharging (depending on needs). Afterwards, Accurec employs thermal treatment (in rotary kiln, currently via external service) to crack and pyrolyze the organic components. The temperature in this rotary kiln treatment is limited to 600C, to avoid oxidization of certain unnoble metals like Al. The off-gas is cleaned by afterburner, quenching system and the excess energy from incineration of organic components is trans-formed to high pressure steam and used in industrial processes. Thereafter, the pyrolyzed battery cells are screened, crushed and classified/sorted by Accurec's inhouse multi-step mechanical separation plant. Output products include steel fraction, Cu/Al fraction and Co- and Ni-rich electrode powder. The steel fraction and Cu/ Al fraction can be delivered to corre-sponding metal smelting facilities for metal recovery, while the CoNi concentrate can be for-warded to pyrometallurgy and subsequent hydrometallurgy plants for final recovery of Co- and Ni-salts or -metals. With course of technology development, Accurec is currently developing and installing new technics, which will be placed into operation 03/2021 at the company's Li-ion battery recycling center in Krefeld. Besides nickel, cobalt and copper, the recovery of lithium and graphite are targeted in a future step. September 2020 , Page 23 Figure 8: Current Li-ion batteries recycling process at Accurec (2020) Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 24 4.1.3 Nickelhtte Aue (Germany) - [Thermal + Pyro + Hydro] Nickelhtte Aue GmbH (NHA), founded in 1635 in Aue, Germany, is known as pyrometallurgical works and recycling company. NHA is specialized in the recycling of waste materials containing non-ferrous metals. The facility is especially interested in Nickel, Copper, Cobalt, Vanadium, Molybdenum and precious metal containing spent catalysts from chemical and pharmaceutical industries but also from petrochemical industries and from hydrogenation processes of oils and fats. But they are also able to treat other kinds of residues like ashes, dusts, grindings, liquids and slurries as long as they contain one or a combination of the above-named metals [18]. Since 2011, NHA started to get involved in recycling of Li-ion batteries [18]. The recycling process applied is mainly composed of thermal pre-treatment, pyrometallurgy and subsequent hydrometallurgy. The flowchart of Nickelhtte Aue's battery recycling process is shown in Figure 9 [19]. In the pyro-treatment step, the batteries can be melted in a short drum fur-nace (batch-wise furnace), producing NiCoCu-Matte. The company also partly uses a rotary kiln as an alternative to thermally pretreat the batteries. More detailed information about the final hydrometallurgy treatment are currently not available. The process capacity is said to be 7000 t/a by using thermal rotary kiln pre-treatment. Figure 9: Li-ion&NiMH batteries recycling process published by Nickelhtte Aue [19] September 2020 , Page 25 4.2 Processors outside EU 4.2.1 SungEel HiTech (South Korea) - [Mechanical + (Thermal +) Hydro] SungEel Hi-Tech Co., Ltd, headquartered in Korea, Gunsan City, is a resource recycling company established in 2000 to recover precious metals and valuable metals from industrial wastes [20]. In 2017, the corporate split into Sungeel Hi-Tech (SHT) and Sungeel Hi-Metal. While Sungeel Hi-Metal focuses more on treatment of electronic industrial waste and petro-chemical industry waste, Sungeel Hi-Tech focuses on Li-ion battery recycling [20] [21]. Today, SungEel Hi-Tech recycles over 8,000 tons of spent LIBs and scraps annually [22]. The LIB recycling process of SHT consists mainly mechanical pretreatment and hydrometal-lurgical process. The Li-ion batteries (mainly production scraps) are grinded into water, to avoid fire. Subsequently, the grinded material is separated mechanically into a) ferrous metal fraction, which is forwarded to ferrous metal processing plant, b) Cu, Al foils, which is forwarded to non-ferrous metal processing plant and c) battery active mass, which is forwarded to inhouse hydro-process (leaching, precipitation, etc.) for final recovery of metal-salts. The process is said to recover lithium phosphate [22] possibly, but not yet confirmed. According to [24], in 2018, SHA has produced 1,000 tons of cobalt, 720 tons of manganese, 720 tons of nickel and 1,000 tons of lithium (lithium carbonate equivalent). In 2020, SHT announced to bring a new hydro system at its headquarters factory in Gunsan online [24]. This will triple the site's capacity to 24,000 tons per year of LIB. SungEel also have bases outside Korea. In 2018, SungEel HiTech and Metallica Commodities Corp. LLC (MCC, headquartered in US) announced the establishment of a joint venture, SMCC, in New York, US. It is announced that the joint venture will initially recycle over 3,000 tons of spent lithium-ion batteries annually [22]. This joint venture facility in New York is due to start up in 2020 [24]. From the permit [25], the process of the joint venture facility in New York includes main steps as: 1) drying/heating in rotary dryer (T<600C), 2) grinding and 3) hydrometallurgical process. Therefore, a thermal pretreatment step is introduced in the process. 4.2.2 Kyoei Seiko (Japan) - [Pyro] Kyoei Seiko is a Japanese steel manufacturer, who also collects and treats industrial and medical wastes. The subsidiary Kyoei Industrial Co. Ltd. utilizes its electric arc furnace technology to treat EOL Li-ion batteries and other wastes [26]. The recycling flowchart can be seen in Figure 10. Li-ion batteries are charged in electric arc furnace (EAF) together with other solid wastes. After melting in EAF, the molten metal is further treated via steelmaking technologies of the parent company to produce steel. The generated slag can be used for road construction. More details about the process are not available. It is noted that direct charging of high Li-ion batteries into EAF may cause safety risk because the explosion of cells could make the molten metal splashing out. Therefore, the ratio of Li-ion batteries in the mixture must be controlled below a small scale level. The recovery rate of Ni, Co, Cu is not known or not verifiable for battery feedstock due to co-processing with other wastes. Additionally, we can speculate that light metals like Al and Li are lost in slag. Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 26 Figure 10: Flow chart of waste (including Li-ion batteries) recycling process published by Kyoei Seiko [26] 4.2.3 Dowa (Japan) - [Thermal + Pyro + Hydro] Dowa Holdings Co., Ltd., a Japanese company founded in 1884, has relatively wide business divisions, including environmental management & recycling, nonferrous metals, electronic materials, metal processing, and heat treatment. In November 2010, Dowa announced, that its subsidiary, Dowa Eco-System Co., has commercialized its lithium-ion battery recycling business at its existing facilities. EOL Li-ion batteries as well as scraps generated from the battery manufacturing process will be recycled [27]. Utilizing existing facilities such as Dowa's industrial waste intermediate treatment plants, each year over 1000 tons of used lithium-ion batteries can be received and treated [27]. The main treatment steps include dismantling (of packs/modules), thermal pretreatment (roasting), pyro- and hydro-metallurgical processing. The thermal pretreatment is performed in a rotary kiln. Afterwards, the pyrolyzed materials are sent to Dowa smelter. In the final step, the materials are recovered via Dowa hydro-process, which has run over many years to extract metals such as copper and gold from wastes including electronics [28][29]. High-purity cobalt is also reported to be produced. More information about the recycling technologies is not available. The recovery rate of Ni, Co, Cu is unknown, but can be compared with existing industrial processes, according to Schema in Figure 5. September 2020 , Page 27 4.2.4 Brunp (China) - [Thermal + Mechanical + Hydro] Brunp Recycling Technology Co. Ltd. was founded in 2005 in Fushan, China [30]. The main business segments include recycling of spent batteries and cars. Brunp has facilities in Guangdong and Hunan provinces. From 2013 to 2015, LIB manufacture CATL continuously acquired Brunp's stock (to 69.02%) [31] and Brunp became a subsidiary of CATL. It is reported in 2018 that Brunp's annual waste battery (including LIB and other batteries) treatment capacity exceeded 30,000 tons [32]. Therefore, it can be considered that Brunp treats mostly LIB waste materials from production scrap. However, the exact ratio between EOL Li-ion bat-teries and production scrap and other waste is unknown. Brunp reports an annual production of 10,000 tons of nickel cobalt manganese hydroxide. Brunp's Li-ion battery recycling process mainly include discharging, thermal pretreatment, mechanical treatment and hydrometallurgy [33]. The company's hydrometallurgical treatment is based in the facility in the Hunan province. The hydrometallurgical process includes acid/basic leaching, solvent extraction, crystallization, etc. [30] A photo of an acid-leaching workshop from Brunp is shown in the figure below. The company described the LIB recycling technologies in several patents [34][35][36], however, it is unknown which technology is actu-ally installed in production. Main final products from Brunp battery recycling process are Ni-Mn-Co hydroxide, cobalt sulfate, nickel sulfate, cobalt chloride, etc, which are classical products resulted from hydrometallurgical process. It is speculated that the recycling rate of Ni, Mn, Co is high, due to high recovery rate in hydrometallurgical process. But the recycling rate of lithium is unknown. Figure 11: Acid-leaching workshop published by Brunp [30] Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 28 4.2.5 GEM (China) - [Mechanical + Hydro] GEM Ltd. (Green Eco-Manufacturer Hi-tech Co., Ltd) is a recycling company founded in 2001 in Shenzhen, China. GEM processes "Urban Mines", including electronic wastes, battery wastes, discarded cars, Nickel / Cobalt / Tungsten metal scraps, etc. From nickel / cobalt metal scraps and spent Li-ion batteries, GEM separates Co and Ni by hydrometallurgical process and then synthesizes the Co-/Ni-salts or producing ultrafine Co-/Ni-powder. GEM has a designed annual production capacity of 5000 tons of NCM and NCA ternary precursor material. The company shows its recycling process as in Figure 12 [37]. Figure 12: Flow chart of Ni/Co waste and Li-ion battery recycling process published by GEM [37] As shown in the figure, spent Li-ion batteries, together with Ni/Co containing wastes, are primarily comminuted. After the mechanical separation, the comminuted Ni/Co containing material is sent to hydrometallurgical treatment. The material is dissolved into solution and then metal ions such as Cu2+, Al3+, Fe2+, Co2+ and Ni2+ are separated into various solutions. The obtained Co/Ni-containing solutions are subsequently processed through liquid phase synthesis and high temperature treatment to produce Co/Ni-salts for battery production. As mentioned before, the company also announced producing ultrafine metal powders from waste Li-ion batteries. According to patents of the company [38][39][40][41], ultrafine Co/Ni-products may be produced by atomizing-hydrolysis method, ball milling + H2 reduction method, or airflow crushing technology. The ultrafine metal powders can be used in hard alloy production. In a patent [42], mechanical pretreatment of sorting and comminution of spent Li-ion batteries is described in more details. However, the risk evaluation during mechanical separation is not available due to lack of information. Also, information about the removal of other impurities such as electrolyte, PVDF binder is insufficient. As the Co/Ni-products are produced from the mixed materials of batteries and other metal wastes, the specific recycling amount of batteries is not known. Nevertheless, from the bat-tery collection scheme of GEM it is known that around 11,000 t/a of mixed spent batteries are collected [37]. Assuming 20% of them are LIB, one can estimate that the treatment of LIB is about 2000 t/a. September 2020 , Page 29 4.2.6 Huayou Cobalt (China) - [Mechanical + Hydro] Huayou Cobalt Co., Ltd, founded in 2002 in Zhejiang, China, is primarily a supplier of cobalt. Huayou said to aim at achieving a closed-loop industrial chain, and its business sectors include mining (of Co, Ni), cathode material precursor and cathode material production and recycling. Its 100% own subsidiary Huayou Recycling Technology Co. (Huayou Recycling), founded in March 2017 in Zhejiang, focuses on LIB recycling [43]. Regarding the recycling technology, Huayou Recycling's dedicated production line for LIB, which started to put into operation in 2018, contains processing steps such as battery pack/module (automatic) dismantling, cell crushing, material classification and hydrometallur-gical treatment [32]. The existing hydrometallurgical process for Co/Ni-primary production (from ores) in the parent company (Huayou Cobalt) can be applied/ adapted for the hydro-processing of waste Li-ion battery materials. It is announced that the production plant has an annual treatment capacity of 65,000 tons bat-teries (packs) [44]. However, data of current capacity is not available. 4.2.7 Ganzhou Highpower (China) - [Mechanical + Pyro + Hydro] Highpower International Inc., founded in 2001 in Guangdong province, China, is an integrated "clean energy" supplier. The main businesses include R&D, manufacturing and sales of Ni-MH and Li-ion rechargeable batteries as well as energy storage systems. In 2012, the company built a plant in Ganzhou City, Jiangxi province, entering battery and electronic waste recycling business [45]. In 2016, Ganzhou Highpower announced to establish a production plant with treatment capacity of 10,000t/a for waste (NiMH & Li-ion) batteries and production scraps [46]. The current treatment capacity is unknown. Besides recycling, the company reported also involving in echelon utilization of used EV batteries. Regarding the LIB recycling technologies, it is described by the company that it utilizes physi-cal deconstruction (mechanical treatment), pyrometallurgical and finally hydrometallurgical process [47]. More details are not available. Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 30 5. Pilot-scale (<1000 t/a) Li-ion battery recycling processors This chapter will elaborate the pilot-scale (<1000 t/a) LIB recycling processors within EU and outside EU, including the companies backgrounds, LIB recycling capacity, technologies, etc. The processors can be large enterprise or SME, non-dedicated or dedicated battery recyclers. They are categorized as pilot-scale processor because their current LIB recycling ca-pacity is still relatively small. 5.1 Processors within EU 5.1.1 SNAM (France) - [Thermal + Pyro + Hydro] SNAM (Societe Nouvelle d'Affinage des Metaux) is a dedicated battery recycling company founded in 1977 in Lyon, French. The Floridienne group shared its capital since 1996. The main activities are recycling of Nickel-Cadmium, Nickel-Metal-Hydride, Lithium Ion and Alkaline batteries. Especially, over many years the company has recycled Nickel Cadmium batteries through pyrolysis, distillation and refining treatments. In 2000, the company announced starting the treatment of the first tonnages of Li-ion batteries [48]. For Li-ion batteries, the company is using basically its NiCd pyrolysis technic for thermal pre-treatment [49]. In the pyrolysis step, sorted Li-ion batteries are heated so that their constituent organics are decomposed and incinerated in an afterburner. The remaining battery metals are subsequently sent to non-dedicated primary metallurgy processors, to recover Co, Ni, and Cu. The recycling efficiency can be estimated to be similar according to their schematized route in Figure 5. 5.1.2 EDI (France) - [Mech (aqueous shred) + unknown] EDI (Euro Dieuze Industrie) is a dedicated battery recycling company, as a subsidiary of Veo-lia SA, located near the Metz-Nancy industrial corridor in French. The company is specialized in four types of batteries: Alkaline, zinc carbon, primary and secondary lithium batteries [50]. It announced a treatment capacity of 5,0006,000 tons of used batteries and portable accumula-tors [51]. EDI battery treatment course is divided into several steps: sorting, shredding, mechanical separation [50]. In the first step, the mixed used batteries are sorted manually. Lithium-containing batteries are shredded in a specially designed process with water flow in order to catch the electrolyte solvents and reduce TR incidents. Subsequently, the crushed batteries go through a vibrating sieve in order to separate the electrode active mass powder and all other materials. Then the iron part is separated by an electromagnetic conveyor belt and finally the last part sorts the paper and plastic from the nonferrous materials on an eddy current disk. In this mechanical treatment process, the final destination of evaporating electrolyte and conducting salts is not clearly described. September 2020 , Page 31 Four products result from mechanical separation: electrode active mass powder, iron scraps, papers with plastics, and nonferrous metals. Iron scraps are further recycled through existing iron metallurgy. Papers and plastics are sent to incineration and energetic valorization. The electrode active mass powder is said to be further treated to recover cobalt and copper via pyrometallurgical process [52]. Current implementation status of the pilot plan is not available. 5.1.3 AkkuSer (Finland) - [Mechanical + unknown] AkkuSer Ltd. is a dedicated battery recycler founded in 2006 in Nivala, Finland [53]. AkkuSer treats Alkaline, NiMH, and Li-ion batteries with a so-called "Dry- technology", a mechanical treatment process, which described in more details in the next paragraph. The Dry-Technology was described by AkkuSer in several Patents [54][55]. In the process, spent batteries undergo two-stages crushing. During the first crushing process, a cyclonic air separator removes all the electrolyte and reaction gases, including hydrogen and oxygen, accumulated within the crusher. The gases are subsequently cleaned by filters. In second crushing process, the crusher reduces the battery pieces to 0-6 mm. All the gases and dust are removed/collected in a second air mover. The resulting powder passes through a magnetic separator and extracts iron flakes. The output iron flakes are reclaimed by smelting, while the metal concentrate powder is delivered as raw material to pyrometallurgical metal refineries. Impact of generated toxic gases are not clearly described. Technically, highly volatile electrolytes and generated HF/HCl cannot be segregated just by described technologies before emitted to environment. 5.1.4 Redux (Germany) - [Thermal + Mechanical + unknown] Redux Recycling GmbH is a dedicated battery recycler, founded in 1997 in Dietzenbach, Germany [56]. Redux offers battery recycling services from sorting to recovery of various systems (NiMH, Alkaline, Li-ion). In June 2018, Saubermacher and Redux announced to open a new recycling plant in Bremerhaven for Li-ion batteries [56]. The shredding system is said to be capable of processing all types of pre-pyrolysed lithium-ion battery with an annual treat-ment capacity of 10,000 tons. Regarding the Redux's Li-ion treatment process, as described in [56] it contains four steps: 1) Discharging, 2) Disassembly, 3) Thermal treatment (by external service, in rotary kiln) and 4) Mechanical processing (in-house). The output products include steel, aluminum, copper, plastic (from disassembly) and active mass (in an unknown segregation degree). Final treatment destination of Co/Ni containing active mass is unknown. Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 32 5.1.5 Duesenfeld (Germany) - [Mechanical + Hydro] The Duesenfeld GmbH, started operation in June 2018 in Wendeburg, Germany. The recycling facility has been specialized in the mechanical treatment of Li-Ion batteries without thermal deactivation. Currently, acceptance of batteries for recycling is stopped, due to technical problems (06/2020). Duesenfeld's recycling process is published in Figure 13 [57]. After discharging and disassembly to cell or module level, the spent batteries are mechanically comminuted by crushing in inert atmosphere. The electrolyte is announced to be evaporated, condensed and collected. The remaining crushed material mix then undergoes further mechanical separation. Apart from the recovered electrolyte, Duesenfeld's output fractions after mechanical processing are iron parts, an aluminium-copper fraction, active mass powder, and additionally plastic parts from housing and separator foils. This process is announcing to recover electrolyte instead of being lost in a thermal pretreatment. Neither a proof of quality of recycled electrolytes has been verified, nor how to re-use it. Also, the information about how to solve the problem of HF-corrosion of machines is not clearly described. Additionally, the machines are not explosion-proof, which poses safety risk. After mechanical separation, it is reported that the active mass powder can be forwarded to hydrometallurgical treatment to recover lithium, nickel, cobalt, manganese and graphite. It is noted that the hydro-process has not installed, and it is only proven in lab-scale tests. Figure 13: Mechanical recycling process published by Duesenfeld [57] September 2020 , Page 33 5.1.6 Promesa (Germany) - [Mechanical (aqueous shred) + unknown] PROMESA GmbH & Co. KG, headquartered in Hettstedt, Germany, was founded in 2016 specifically for the treatment and recycling of lithium battery systems. It is a subsidiary of VVG (Verwertungs- und Vertriebsgesellschaft), which was founded in 1991 in Germany and specializes in the disposal of industrial wastes. Promesa mechanically treats lithium-ion batteries, ranging from small household to large EV battery packs [58] [59]. The large battery systems are dismantled prior to special treatment areas. Regarding the recycling technology, a special feature of their mechanical treatment is that the batteries are shredded under aqueous solution, by which the safety can be obviously improved. More details about the processing are not available. It appears that the generated acids and electrolytes are ending in aqueous solution without known further destination. Subsequent mechanical process separates the materials into different fractions. It is reported that Co/Ni-containing materials are recovered in a subsequent hydrometallurgical process [60]. The current annual treatment capacity is unknown but estimated to be at low pilot scale. 5.1.7 TES-AMM (formerly: Recupyl) (France) - [Mechanical (inert gas)] Recupyl is a dedicated battery recycling company founded in 1993 in the area of Grenoble, France. Recupyl recycles batteries including alkaline, zinc-carbon and lithium-ion batteries, via mechanical separation technology. At Grenoble plant, a pilot test with capacity of several hundreds of tons per year was installed [61]. Since 2007, Recupyl has sold several patent licenses [62] or set joint ventures. In 2019, Recupyl went bankrupt, so that certain subsidiaries became independent (Recupyl Poland) or have been passed to other companies, e.g. TES-AMM, an international electronics waste recycler based in Singapore [63]. Recupyl's mechanical separation process after discharging consists of 1) Shredding of Li-ion batteries in inert gas atmosphere (N2), 2) Grinding by pin mill and 3) Sieving of materials to fractions of plastics, Al, Cu, Steel and Active Mass powder. Their capacity is not available but expected to be low. The active mass generated needs to be pre-refined by pyrometallurgy before submitting to hydrometallurgical process. Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 34 5.2 Processors outside EU 5.2.1 Retriev (US) - [Mechanical (aqueous shred) + Hydro] Retriev Technologies (formerly "Toxco Inc."), headquartered in Lancaster, is a battery recy-cling company founded in 1990s in U.S.A [ ]. Retriev provides recycling technologies for Lead acid, NiCd & NiMH, Li-ion, Li-primary and alkaline batteries. In 2009, Retriev was awarded 9.5 million dollars from US Department of Energy to build a new plant in Lancaster, Ohio to support US lithium-containing battery recycling, especially hybrid and electric vehicle batteries. For both Li-primary and Li-ion batteries, Retriev applies mechanical pretreatment. Initially, the Retriev Li-battery recycling process was designed to treat primary lithium metal batteries, mainly from military applications, in the early 1990s [64], in which cryogenic cooling with liquid nitrogen is applied for safety consideration [64]. Retriev's Li-ion recycling process mainly consists of following steps [64]: 1) Manual disassembly (of large format batteries), 2) Crushing under aqueous solution, producing three types of materials: metal solids, metal-enriched liquid, and plastic fluff. 3) Further treatment (off-site): The metal solids, containing various amounts of copper, aluminum, and cobalt (depending on the type of Li-Ion battery processed), can be fur-ther treated to recover the metals for new products. The metal-enriched liquid is solidi-fied using filtering technology and is sent off-site for further metal purification. In patent US 8616475 (B1) [66] in 2013, Retriev (Toxco) demonstrated a newly developed Li-ion recycling process, including main steps of crushing, screening, filtration, froth flotation of carbon, filtration and thermally re-generation of LIB cathode material. The company announced to commercialize the described process. However, the current status does not show an implementation into operation. 5.2.2 Kobar (Korea) - [Mechanical + Hydro] Kobar Ltd, located in Seoul, Korea, is a specialized recycling company for rechargeable batteries such as NiCd, NiMH and Li-ion batteries. For recycling of NiCd and NiMH batteries, Kobar applies mechanical crushing and subsequent pyrometallurgical processes, producing Fe-Ni-alloys and Cd-metal. For recycling of Liion batteries, information from the company's web page shows that crushing, screening and hydrometallurgical processing are applied, as seen in Figure 14 [67] [68]. Cobalt-containing powders are the main product from recycling of Li-ion batteries. Very little details of the treatment are not published. One can see from the flowchart that after sulfuric acid leaching, two fractions are generated: a) cobalt oxalate, which probably produced by precipitation with ammonium oxalate; b) a filtrate containing Li, Fe, Al and Cu. However, the post treatment of the filtrate is unclear. It is reported that the recycling capacity of Kobar is 1,200 t/a for NiCd and NiMH batteries, and 900 t/a for Li-ion batteries [67]. September 2020 , Page 35 Figure 14: Flowchart of Li-ion battery recycling process published by Kobar [67] 5.2.3 JX Nippon (Japan) - [Thermal + Mechanical + Hydro] JX Nippon Mining & Metals Corporation is a large international company based in Japan, 100% owned by JXTG Holdings, Inc. The businesses mainly involve non-ferrous metals min-ing, processing and manufacturing. In 2010, the company launched a commercial feasibility trial of lithium-ion battery recycling technology at their Tsuruga Plant. It is reported that in 2019 it has achieved operation using recycled materials only, mostly end-of-life lithium-ion batteries [69]. Some 600 tons of end-of-life lithium-ion batteries, collected from smartphones and personal computers, are processed annually, recovering at least 100 tons of cobalt. In addition, it has recovered lithium in the form of lithium carbonate. Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 36 Figure 15: Flow chart of Li-ion battery recycling process published by JX Nippon Tsuruga [69] The process of Li-ion battery recycling at JX Nippon Tsuruga is illustrated in Figure 15. To recover valuable metals such as cobalt, nickel, and lithium, end-of-life lithium-ion batteries are incinerated (roasted) and the battery electrolyte and other organic matter are removed, destroying the functioning as batteries. Next, crushing and separation are performed, and "bat-tery powder" containing valuable metals in concentrated form is extracted. The powder is dissolved in acid, resulting in a solution containing the valuable metals. Subsequently, solvent extraction (SX) is then used to separate and recover the target metals [69]. More details of the process are not available. In addition, the company claimed to pursue closed-loop recycling, by exploring technology for extraction of Co/Ni-sulfate of a quality that will enable the raw materials extracted from lithium-ion batteries to be used again as lithium-ion battery materials. To conduct tests of their stable mass production, verification equipment is being built in Hitachi City, Ibaraki Prefecture, and was expected to go into operation in fall 2019 [69]. Current status of implementation is not available. The treatment capacity is expected to be low. 5.2.4 Telerecycle (China) - [Mechanical + Hydro] Tele Battery Recycling Co., Ltd., founded in Shenzhen, China in 2007, is a small-medium size dedicated battery recycling company. Telerecycle has a R&D center in Shenzhen and a production base in Shangrao. The annual treatment capacity of Shangrao plant is 3000 tons of waste batteries (including Li-ion and other batteries) [70]. The current treatment capacity of merely Li-ion battery is unknown. The company also build a battery collecting platform, which has 32,130 collecting stores/points and collects over 3 t/d of waste batteries. The data is expected to expand and to achieve 20 t/d in 2019 [70]. The current capacity is not available yet. In addition, to recycle EV Li-ion batteries, the company has developed automatic disassembly line for automotive Li-ion battery packs [71]. Regarding recycling technologies, Telerecycle recycles spent Li-ion batteries via mechanical separation and hydrometallurgy [72]. Main products include Co-sulfate and lithium carbonate. More details about the process is unfortunately not available. September 2020 , Page 37 5.2.5 Guanghua (China) - [Mechanical + Hydro] Guangdong Guanghua Sci-Tech Co., Ltd., founded in 1980 in Guangdong province, China, is a specialty chemicals service provider. The main products include high-performance electronic chemicals, chemical reagents and "new energy" materials [73]. With the knowledge and experience in hydro-treatment of electronic chemicals, Guanghua started to enter Li-ion battery waste recycling in recent years. In September 2018, Chinese Ministry of Industry and Information Technology announced a list of first five Chinese companies that comply with the "Specifications for Comprehensive Utilization of Used and Scrapped New Energy Vehicle (NEV) Batteries" [74]. Guanghua was in the list (rest four: Hauyou Co-balt, Ganzhou Highpower, GEM, Brunp). Regarding the LIB recycling process, Guanghua reported to apply mechanical pretreatment and hydrometallurgy [75]. The hydrometallurgy plant is based in the Gaolangang factory, while the Fushan factory focuses on the second-life utilization and pretreatment of used EV battery packs, including battery evaluation, refurbishment, disassembly. etc. The mechanical separation of battery materials could be done by external process. After mechanical pretreatment, the resulting active metals (Co, Ni, Mn) containing material goes back to Gaolangang factory for hydrometallurgical treatment. More details of the treatment technologies are not available. It is reported in April 2019 that a production line with capacity of 10,000 t/a of used EV battery packs has been built [76]. However, the current treatment capacity is unknown. Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 38 6. Lab-scale novel Li-ion battery recycling technologies This chapter will give examples of lab-scale LIB recycling (sub-) treatment technologies. Because there are too many related literatures, only several selected examples are described here. They can be developed by enterprises, research organizations or universities. 6.1 Mechanical separation and reconditioning for direct reuse ("Direct Recycling") A so-called "direct recycling" process, in which cathode or anode materials are separated (by mechanical separation), reconditioned and then directly re-used for manufacturing LIB [77], has also attracted many people's attention. The ERLOS GmbH, a recycler of plastic waste (especially from the automotive sector), founded in 2002 and headquartered in Zwickau, Germany [78], pursues this direct recycling strategy in recent years for recycling of LIB. The main recycling steps include mechanical separation of electrodes, followed by washing, filtering and drying (see Figure 16). More details about the process are described as follows [16]: 1) After discharge (surplus of energy used within the company), the battery packs are dismantled com pletely to battery cell level mainly by hand. 2) Subsequently, the pouch cells enter an encapsulated chamber flooded with inert gas to prevent fire or explosion where the pouch are automatically opened and separated into anodes and cathodes by the help of robots. This automation is a further safety measure in contrast to manual processing. The electrolyte vapor is collected by an exhaust system with an activated carbon filter that has to be exchanged regularly. Beside the electrodes, the separator foils are collected for plastic recycling or for thermal usage in incineration plants. 3) The cathode and anode electrodes are treated separately in the following washing process. The cathode is treated with water and/or sodium hydrogen carbonate solution at 20-30C and with a maximum of 90 bar air pressure to separate the aluminum foil and the coating (active mass contain ing nickel, manganese, cobalt and carbon). 4) The liquid fraction containing the cathode materials is filtered, pressed, washed and dried in a gas oven, obtaining marketable recycled cathode materials that can be used partially for the production of new cells. However, the recycled cathode materials need to be mixed with primary cathode ma terials. All collected aluminum foils from the cathode are sent to an independent metal recycler. 5) The anode is treated in the same way, separating and recovering the copper foil and the graphite active mass. However, the recycled graphite material is not used for battery anodes, but for other purposes. All collected copper foils from the anode are dried and sold for third party recycling. 6) Because the washing water contains parts of the electrolyte and other contaminants it is treated and cleaned in a sewage treatment plant. September 2020 , Page 39 According to the company, this kind of recycling technique is applicable to pouch and prismatic cells, but less suitable for cylindrical cells. Additionally, direct recycling could struggle to accommodate feedstocks of unknown or poorly characterized provenance and cross contamination while processing, and there will be commercial reluctance to re-use material if product quality is affected. Therefore, it might be more meaningful for treatment of production scrap or a pure type material rather than battery mixtures. Moreover, the product quality still needs to be proven. Figure 16: Direct recycling process including mechanical separation and reconditioning ap-plied by Erlos [16] 6.2 Liquid/Supercritical CO2 for electrolyte extraction Steven E. Sloop et al. described a method of removing electrolytes by using supercritical fluid in a patent (US 7.198.865 B2) in 2007 [79]. In 2015, M. Grtzke et al. from MEET Battery Research Center of University of Muenster also published a study of extraction of electrolytes with liquid and supercritical CO2 [ ] in scope of LithoRec II project. It reported that linear carbonates like DMC and EMC, respectively, were better extracted with liquid CO2, whereas the cyclic carbonate EC was recovered in higher amounts with supercritical CO2. The best recovery rate of electrolytes reported by this paper is 89.13.4 wt%. Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 40 In 2020, S. Sloop, et al. published a direct recycling case study [81], in which electrolytes are extracted with CO2. The process is demonstrated in Figure 17. It is also a so-called direct recycling process. In this study, the recycled materials are re-built in battery cell for testing. It is reported that the final products demonstrated useful capability in the first full cells made from direct recycled cathodes and anodes. Nevertheless, as explained before, the direct recycling process could struggle to accommodate feedstocks of unknown or poorly characterized provenance, and there could be commercial reluctance to re-use material considering its questionable product quality. Figure 17: Direct recycling process with extraction of electrolyte with CO2 [81] 6.3 Froth flotation for separating active mass Froth flotation is a technology for selectively separating hydrophobic materials from hydrophilic. It has been used in mining industry for long time. In Li-ion batteries, anode material, commonly graphite, is naturally hydrophobic, while cathode material such as LiCoO2 is hydrophilic. Therefore, researchers try to use froth flotation to separate these two materials. Zhan et al. [82] demonstrated an experimental work of separating anode and cathode material (fine powder after mechanical separation) using froth flotation (see Figure 18). It was reported that over 90% of anode materials were floated in froth layers, while 10-30% of cathode materials were floated. In terms of purity of graphite particles, froth concentrates contain 16% and 22% of active cathode materials at 60 m and 18 m grinding sizes, respectively. A further upgrading of the purity of graphite materials in the froth products is believed to be difficult. As a result, the authors concluded that the froth flotation is not applicable to produce September 2020 , Page 41 high purity graphite material. Nevertheless, the purity of output cathode material is higher than the output anode material. Detailed purity of cathode is unfortunately not reported. The authors pointed out the purity of cathode material might vary with the feed samples and grinding conditions, which brings concern for re-using the recycled cathode material in new cells. The technology is still under development and still needs to prove its viability. Nevertheless, it provides alternative solution for separation of electrode materials and increases the concen-tration of valuable cathode metals (e.g. Co, Ni) and thus increases the value of active mass powder. Figure 18: Recycling process with froth flotation separation of active masss [82] 6.4 Electrohydraulic Fragmentation using shock waves An innovative treatment technology, electrohydraulic fragmentation using shock waves, was developed within a research project, namely NEW-BAT project in 2016-2019 by Fraunhofer Project Group for Materials Recycling and Resource Strategies (IWKS) and several partners [83]. The innovative core of the recycling process is the electro-hydraulic fragmentation using shock waves. The material is introduced into a liquid medium, such as water or other liquids. The shock waves are generated by an electrical discharge. The shock waves hit the materi-als uniformly. This makes it possible to split the composites at the material boundaries in a non-contact manner and thus achieve a simple and gentle separation of the components [83] [84]. Schematic diagram of the electrohydraulic fragmentation is shown in Figure 19 [85]. The processing flowchart is shown in Figure 20 [16]. First of all, the batteries are discharged and then disassembled to cell level. In the following electro-hydraulic fragmentation step, the cells are opened up and their components are separated by mechanical shockwaves in a fluid medium (e.g. water). Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 42 In a subsequent step, the mixed components are separated mechanically (similar to previously described classical mechanical separation), obtaining similar fractions as those resulting from currently applied mechanical treatments: mixed active mass, plastic parts and separator, metal foils, and cell housing. The active mass has still to undergo further treatment such as hydrometallurgy or separation into anode and cathode materials and refurbishing (direct recycling). However, current processing volumes are still on lab scale and aspects such as energy efficiency and economic feasibility can thus not be assessed yet. The energy efficiency is expected to be low due to high energy consumption. It is also noted that the battery should be deeply discharged before treated by electro-hydraulic fragmentation for safety reasons (to avoid Thermal-Runaway of Li-ion batteries). However, this deeply discharging consumes currently relatively large effort and time in indus-try. Therefore, this method could be more suitable to treat shredded/crushed materials instead of non-deactivated cells considering safety aspect. Figure 19: Electrohydraulic Fragmentation of Li-ion battery material (by Fraunhofer IWKS) Figure 20: Recycling flowchart with electrohydraulic fragmentation by shock waves [16] September 2020 , Page 43 6.5 Sulphate roasting of active mass for early stage lithium extraction In 2013, University TU Bergakademie Freiberg developed lithium extraction technologies within a German project called "Hybrid Lithium Extraction" (German: "Hybride Lithiumgewinnung"), in which lithium is targeted to be extracted from Zinnwaldite mineral as well as from spent Li-ion batteries. In the project, one of the Li-extraction routes is to utilize sulphate roasting treatment to facilitate the separation of lithium from other metals such as Co and Ni (see Figure 21 [86]). It is reported that by roasting with KHSO4, the lithium in pyrolyzed Li-ion material can be transferred to water-soluble phase (Li2SO4) and then it is able to be separated from other metals by water leaching and eventually recovered as Li2CO3 [86] [87]. Figure 21: Flowchart of lithium extraction process with sulphate roasting (based on [86]) In 2020, two papers [88] [89] also reported the idea of selective extraction of lithium by sulfateroasting treatment. In the study, further investigations regarding treatment conditions (temperature, time, etc.), reaction mechanism and product characterization have been made. It is reported that in sulfation roasting, the metals in NCM cathode powder are selectively converted into water-soluble lithium sulfate (Li2SO4) and water-insoluble oxides (NiCoMn-oxide) via following reaction [88]: 2LiNixCoyMnzO2 + H2SO4 = Li2SO4 + 2NixCoyMnzOa + H2O + (3-2a)/2 O2 (8) The process provides alternative to extract lithium from early stage. It is still in lab-scale and further investigation/optimization (e.g. effect of different roasting additives, evaluation of the conversion efficiency of different metals) should be investigated. Also, further study regarding energy efficiency, economic feasibility, environmental impact, etc. should be made in the future. Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 44 7. Evaluation of various Li-ion battery recycling processes According to EU-legislation, a recycling process is complete when, at the end of the process chain, a specified, tradable end product has been produced outside the waste regime. In the present business area, this means predominantly products after hydrometallurgical refining, in the form of a Ni/Co/Cu metal, sulphate or carbonate depending on the process. Since all industrial available processes available today must pass through this hydrometallurgical and upstream pyrometallurgical main treatment, the technical and economic comparison of processes is essentially limited to the pretreatment step. A comparison of various processing routes is summarized in Table 7. The preparation steps (e.g. dismantling and discharging) are not shown in Table 7. However, they also have great impact on the whole recycling processes. A chosen procedure can only generate a long-term advantage if a large electric mobile battery does not necessarily have to be dismantled manually before the first treatment step. The designs and strategies of car manufacturers are very different and range from structured modular construction to compact, non-repairable disposable batteries. As a consequence, in the future there will be batteries that can be disassembled by robotics as well as those that cannot be dismantled, i.e. those that are strongly bonded/glued. The technical pretreatment plants must therefore be set up for the expected different dimensions and designs in the long term. The same applies to the discharge step, which could be a bottle neck of a recycling process (as far as discharging is applied in the process). This upstream sub-step is technically demanding, because theoretically the manufacturer would have to decode the access to the BMS (battery management system) in order to diagnose and unlock the high voltage port. However, since EOL batteries are mainly electro-technically defective, the only way to open the battery with high voltage trained personnel and to avoid the safety installations is to use the primary voltage terminals for ohmic discharge. This discharging process is time-, space- and personnel-intensive as well as logistically complex, whereby the feeding of residual charge into a power grid means a subordinate revenue. Using conservative forecasts (e.g. about 250,000 EOL battery units in 2030 in the EU), the feasibility of the upstream discharge step appears unrealistic and thus has restrictive implications for the spread of various recy-cling routes discussed below. September 2020 , Page 45 After 15 years of international research and development efforts, it is striking, based on Figure 5 and Table 7, that only those process combinations (Route 4 and 6), which integrate the steps of pyrolysis of the battery cell with subsequent pyrometallurgical pre-cleaning, have achieved industrial relevance. This is mainly due to the fact that in these two steps, impurities and unwanted battery components (e.g. organic solvents) are removed for the final refining in hydrometallurgy. Without removal, these impurities would cause problems and hinder the ex-traction of the target metals Co, Ni, Cu (see Table 8). Table 7: Comparison of the current pilot and industrial LIB recycling routes from technical and economic points of view Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 46 Table 8: Possible impurities and their consequences for hydrometallurgical refining Accompanying material Electrolyte (e.g. EMC, DMC) Problem formation in hydrometallurgy Formation of organochlorine compounds, toxic gases, increased acid consumption, costs for pre-wash required Troubleshooting Evapora-tion/decomposition by thermal pretreatment PVDF (Adhesive; 100% in AM) Insoluble in acids and remains in the filter cake, increase of disposal costs Decomposition by thermal pretreatment LiPF6 (conducting salt; 100% in AM) HF-gas formation, fast corrosive destruction to the equipment; LiF formation, therefore, Li depletion in aqueous and metal-containing phase Decomposition by thermal pretreatment Mn Al and Fe Plastic residues (separator, sleeve, cable co-vers, etc.) Graphite (100% in AM) Lithium Iron Phosphate (100% in AM) Silicon (LiB Gen. Si Ano-de) Increased operating costs due to necessary precipitation and disposal, as well as cross-contamination in Fe and Al fraction, more difficult recycling opportunity Increased operating costs due to necessary precipitation and disposal as waste. Al reduces filtering efficiency. Additional filter expenditure; disposal costs for incineration Foam formation with an impact on the plant construction and cost of process additives Formation of stable phosphates of target metals (Co, Ni), environmental hazardous wastewater with phosphates, corrosion due to gas formation, HF favoritism, basic safety concerns, filtration problems Gel formation, increased filtration efforts and disposal cost of waste Slagging Pyrometallurgy Slagging Pyrometallurgy Decomposition by thermal pretreatment Reducing agent Pyrometallurgy Slagging Pyrometallurgy Slagging Pyrometallurgy The pre-cleaning effect of pyrometallurgy also increases the process robustness, as impurities such as Cd, Pb, K, Zn, La etc. from the missorting of other battery systems or electronic components will be practically contained in the mass production process. If iron and aluminum from housings have not or only partly been removed beforehand by mechanical steps, they will be slagged here as well. This diminishes the recycling efficiency (RE) and overall makes it harder to reach the quota of 50 % given in the Battery directive (2006/66/ EC). In order to achieve this minimum percentage of RE for LiB, however, the abundant graphite must also be used. For example, it can be used as a substitute for reducing agents in pyrometallurgy, which is permitted according to EU/493/2012, or via material recovery, which has not yet been proven on an industrial scale. Pyrolysis as a pretreatment step has several functions: On the one hand, it is intended to completely remove organic matter which is undesired in hydrometallurgy. The organics can be oxidized in a controlled manner in state-of-the-art afterburning plants and/or evn used as secondary energy source. On the other hand, it should liberalize the active masss with their target metals, which are permanently bonded to the cathode by the PVDF. If this adhesive bond is not thermally decomposed, it will be difficult to separate the active mass from the electrode foil. Purely mechanical stress cannot loosen this bond, resulting in considerable loss of target metal through cross-contamination. After purely separation by mechanical pretreatment, the cath- September 2020 , Page 47 ode foils including AM are found in many output fractions, so that the dissipative AM losses increase up to 40 to 60 % [ ] and limit the economic efficiency of the process (as the valuable Co, Ni are in AM fraction). With regard to process safety, pyrolysis also has the advantage of controlled removal of flammable and explosive gas mixtures from electrolytes and decomposition products. It also guarantees a targeted neutralization of the hydrofluoric acid formed. If, on the other hand, LiB are mechanically broken down in the first step, the equipment components (feed, shredder, discharge, intermediate buffering, storage, etc.) have to be, but are usually not explosion-proof and cold. The HF gas, which is spontaneously generated in contact with any available moisture to HF-acid, condenses in the system segments and destroys them corrosively within a very short time. Moreover, highly volatile electrolytes form explosive gas mixtures with atmospheric oxygen and can be self-ignited, as a partial residual energy of the cells can never be completely avoided and short-circuiting potentially occurs. In addition, some smaller plants active in Europe using this mechanical pretreatment could not conclusively show the fate of the evaporated electrolytes. The overall economic efficiency of recycling processes is determined by their cost composition, i.e. capital, general operating and personnel costs, versus revenue composition ac-cording to the quantity and quality of the metals recovered. The necessary investments and thus capital costs of the two pretreatment and two main treatment steps increase exponentially in the following order of ranking: mechanical treatment -- pyrolysis -- pyrometallurgy -- hydrometallurgy. Following this order, the complexity of the technologies is increasing considerably, so that the scaling of the plants must be increased in order to operate economically. To date, due to the economic advantage of scaling, the intermediate product active mass obtained from the pretreatment from EOL batteries is mostly fed into these large industrial metallurgy plants, which process mostly primary and secondary raw materials with a suitable mixing ratio of second-ary feedstock on a scale of 50,000 to 300,000 t/a. The maintenance costs per ton of treated LIB are inversely proportional to the capital costs, especially in the case of mechanical pretreatment (Route 1, 2 and 3), since the unavoidable hydrofluoric acid produced there not only increases the maintenance and occupational safety costs, but also leads to a rapid total loss of equipment components and reduces depreciation times to a few years. The additional primary energy consumption via the pyrometallurgical Routes 3, 4 and 6 incorporating the pyrometallurgical step is commonly seen as a disadvantage. However, these additional costs are compensated by the decreased operating costs in the hydrometal-lurgical step. If the active mass obtained by shredding and classifying is not pre-cleaned by pyrolysis and/or pyrometallurgy, as in Routes 1, 2 and 3, the hydrometallurgical effort would have to be significantly increased. It has to be mentioned here that this has not been proven in large scale, but prognoses of additional chemical consumption, gas formation precautions, additional precipitation stages and disposal costs have been mentioned by experts. In addi-tion, there is a cost-intensive consumption of activated carbon in the mechanical pre-treatment process, which is used to absorb the evaporated electrolytes from off-gas to meet requirements of emission standards. As a result, in the Routes 1, 2 and 3, besides the costs of dismantling and discharging, the additional maintenance and replacement requirements, smaller scaling and poorer expandability of the plants, as well as the significantly Comparative study of Li-ion battery recycling processes Reiner Sojka*, Qiaoyan Pan, Laura Billmann | ACCUREC Recycling GmbH September 2020 , Page 48 higher per-sonnel costs and off-gas cleaning cost have an unfavorable effect on overall profitability. On the other hand, as the revenue comes from the recovery of Co, Ni and Cu, additionally recovered materials in Routes 1/2/3/5/6 such as aluminum or steel, regardless of their various qualities due to different processing technologies, do not represent an economically decisive factor. Only the recovery rate of the three targeted metals determines this economic contribution, so that the high losses due to cross-contaminations in the mechanical pretreatment lead to significant disadvantages. In the business area of household LiB, the leverage of the recoverable value with an average significantly higher cobalt content is so big that the process selection of routes 1/2/3 is uneconomical due to the dissipative losses of typical targeted met-als in the process. In addition, the revenues from lithium and graphite extraction have so far not contributed to profits in any of the existing pilot-scale or industrial recycling plants and have only been proven at best on a laboratory scale. September 2020 , Page 49 8. Summary In summary, the present study shows that a variety of chemical-physical reactions occur during the pretreatment of batteries, both in the uncharged and partially charged states. These reactions always produce environmentally hazardous, human-toxic, highly corrosive, process-relevant substances, as well as explosive gas mixtures, which must be handled safely in LIB pretreatment process. In general, current recycling processes for EOL Li-ion batteries can be divided into four differ-ent process steps, namely Preparation, Pre-treatment, Main-treatment with Pyrometallurgy and Hydrometallurgy, which can be combined in six different possible sequences. Currently only two of these (Route 4 and 6 in Table 7) have proven their technical feasibility and indus-trial maturity and compete with each other after implementation in commercial enterprises. Both of them involve the sub-steps of pyrolysis and pyrometallurgy, which only appear to be disadvantageous considering their higher energy requirement. In fact, however, an active mass obtained from only mechanical pretreatment cannot be refined directly into the end product in a hydrometallurgy process. Without the pre-cleaning in the two thermal stages, its impurity content and high load of organics and fluorine's would lead to uneconomically high additional operating costs in hydrometallurgy. In addition, the widely varying composition of the battery active masses (LCO, NMC, LMO, LFP, NCA, etc.) requires thermal selection and homogenization for the input material of hydrometallurgy. This minimizes the operating costs of the entire process route with relatively low losses of targeted metals (Co, Ni, Cu) and also has a positive effect on the ecological balance, since the production and use of additional operating materials, as in other process routes, is not necessary. A further improvement or variation of the possible process steps, in particular with the aim of additional recycling products (Li, Graphite), energy savings or lower losses, is to be technically aimed at in the future. It is noted that only when the quantity of active mass generated has increased (due to market development) to a certain extent, the installation of an overall pro-cess chain (including hydrometallurgy) specifically designed for EOL-battery sector becomes economically feasible. Several novel lab-scale LIB recycling technologies have been presented. However, the commercialization feasibility of those lab-scale (sub-) processes still needs to be proved. 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