Preprint of "Optimized Thermal Treatment of Lithium-Ion Battery Components as a Basis for Sustainable Pyrometallurgy"

1 Low-Temperature Pyrometallurgical Recycling Pre-Treatment for Lithium-Ion 1 Batteries: Understanding of Thermal Decomposition and Surface Changes 2 3 Anna Pražanová a), Jan Kočí a), b), Jonáš Uřičář a, c), Dominik Pilnaj a), Daniel-Ioan Stroe d), and 4 Vaclav Knap a) 5 a) Department of Electrotechnology, Faculty of Electrical Engineering, Czech 6 Technical University in Prague, Prague, Czech Republic 7 b) Department of Glass and Ceramics, University of Chemistry and Technology 8 Prague, Technická 5, 166 28 Prague, Czechia 9 c) Department of Polymers, University of Chemistry and Technology Prague, Prague, 10 Czech Republic 11 d) Department of Energy, Aalborg University, Aalborg, Denmark 12 13 * Corresponding author. E-mail address: [email protected] (A. Pražanová). 14 15 Abstract 16 Escalating global lithium-ion battery demand necessitates efficient end-of-life management. 17 Pyrometallurgical recycling offers a promising route for metal recovery and environmental 18 impact minimization. However, optimizing low-temperature pre-treatment for complete 19 organic removal while preserving active material integrity remains challenging. This study 20 investigated thermal decomposition and surface changes of key battery components (NMC622 21 cathode, graphite anode, polymeric separator) from 100 to 800 °C, focusing on the 400-650 °C 22 industrial interval. Material responses were characterized using TGA-MS, isothermal mass loss, 23 and SEM-EDS. A 500 °C treatment was identified as optimal, enabling complete organic 24 carbon removal within one hour without compromising NMC spinel structure or current 25 2 collector degradation. This precise control reduces energy consumption and mitigates 26 hazardous gas release, enhancing environmental sustainability. Findings define parameters for 27 efficient electroactive material separation, providing a practical, scalable, and cost-effective 28 strategy for improving battery recycling. This work advances low-temperature 29 pyrometallurgical processing understanding, supporting a circular economy for critical 30 materials. 31 32 Keywords: lithium-ion battery, recycling, pyrometallurgy, high-temperature treatment, 33 thermal decomposition, surface changes 34 35 1. Introduction 36 The escalating global demand for lithium-ion batteries (LIBs), especially in electric 37 vehicles (EVs), necessitates efficient and sustainable end-of-life management strategies [1], [2]. 38 In parallel, growing environmental concerns and the limited availability of critical raw materials 39 such as lithium, cobalt, and nickel underscore the importance of developing circular economy 40 solutions that support resource security and industrial resilience [3], [4]. 41 Conventional pyrometallurgical recycling of LIBs typically involves a two-step process: 42 a low-temperature stage (up to ~800 °C) to decompose organics and separate cell components, 43 followed by high-temperature smelting (between 1500 and 1800 °C) for metal recovery [5], [6]. 44 The first stage conditions the internal electrode–separator assembly and mitigates safety 45 hazards from residual electrolytes and flammable materials [7]. This step is often decoupled 46 from metallurgical recovery to control organic degradation better, preserve active materials’ 47 integrity, and facilitate delamination for downstream recovery. However, decomposition 48 involves overlapping reactions with specific onset temperatures, requiring precise process 49 control. Among various chemistries, lithium nickel manganese cobalt oxide (NMC) is widely 50 3 studied due to its prevalence in high-energy cells and complex thermochemical behaviour [8]. 51 Industrially, external casings (polymer-laminated aluminium or nickel) are removed before 52 thermal treatment, so research focuses on the internal stack: cathode, anode, and separator [7], 53 [9]. 54 NMC cathodes are generally thermally stable relative to organic compounds, but their 55 behaviour depends on delithiation and residual binders or salts [10]. While the spinel structure 56 may persist up to 800 °C [11], side reactions involving lithium salts (e.g., lithium 57 hexafluorophosphate, LiPF6; lithium fluoride, LiF; lithium carbonate, Li2CO3) can lead to 58 the release of carbon dioxide (CO2) or hydrogen fluoride (HF) and phosphorus-containing 59 gases [12], [13]. Furthermore, the aluminium (Al) current collector, with a melting point of 60 ~660 °C, may melt and encapsulate active material if temperatures exceed this threshold [14], 61 [15], compromising downstream separation and material quality [6], [16], [17]. Therefore, 62 precise temperature control is critical to remove organic compounds while preserving cathode 63 integrity [18]. 64 Graphite anodes exhibit high thermal stability under inert atmospheres but oxidise in air 65 above ~500 °C, resulting in significant CO2 release and mass loss [19]. Complete combustion 66 typically occurs between 600 and 700 °C, depending on oxygen content in the atmosphere, 67 heating rate, and surface area [19]–[21]. Residual surface compounds, such as lithium alkyl 68 carbonates or Li2CO3, originating from solid electrolyte interphase (SEI) layer degradation, 69 may also affect the oxidation pathway and initiate earlier decomposition [22]. 70 Polymeric separators, typically made of polyethylene (PE) or polypropylene (PP), begin 71 to degrade below 200 °C. This involves initial melting followed by decomposition into 72 hydrocarbon species [23]–[25]. Polyvinylidene fluoride (PVDF), commonly used as a binder, 73 decomposes between 350 and 500 °C, releasing HF, water, and low-molecular-weight 74 fragments [26]. Above 500 °C, remaining residues are mostly converted into stable inorganic 75 4 phases; for example, alumina-coated separators may yield aluminium oxide (Al2O3) after 76 treatment [25]. 77 Given the complexity of multi-component battery architectures, most studies on low78 temperature pyrometallurgical pre-treatment have focused on achieving efficient organic 79 removal while preserving valuable materials, as both are essential for scalable LIB 80 recycling [27]–[30]. Thermal exposure between 500 and 600 °C is widely regarded as a critical 81 step for decomposing polymeric binders and evaporating electrolyte residues, thereby 82 improving the efficiency of mechanical comminution and downstream metal recovery [29]. 83 However, temperatures above 600 °C can lead to the embrittlement or melting of Al foils, 84 complicating their separation. In parallel, elevated temperatures also promote the carbothermic 85 reduction of active materials, such as LiCoO2, which begins decomposing around 700 °C and 86 affects both mass loss and lithium recovery yields. Although reviews of pre-treatment strategies 87 confirm that calcination between 150 and 650 °C efficiently removes conductive carbon and 88 organic compounds, reducing binder adhesion and enhancing separability, they also emphasise 89 challenges related to high energy demands and the release of hazardous gases, including toxic 90 fluorinated species [27], [29]. Despite these advances, a detailed, component-specific 91 understanding of thermal degradation, particularly how controlled heating influences the 92 structure, surface chemistry, and separability of individual active materials and polymeric 93 separators, remains limited. Such insights are crucial for the development of energy-efficient, 94 scalable recycling processes that not only ensure effective organic removal but also minimise 95 unwanted side reactions and preserve material functionality [30], [31]. 96 Thus, this work systematically investigates the thermal degradation and surface 97 evolution of the NMC622 cathode, graphite anode, and polymeric separator across a broad 98 temperature range of 100 to 800 °C, particularly emphasizing the 400 to 650 °C interval 99 commonly utilised in industrial pre-treatment. Detailed insights into material responses were 100 5 provided by employing dynamic thermogravimetric analysis coupled with mass 101 spectrometry (TGA-MS), isothermal mass loss evaluation, and high-resolution scanning 102 electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). The results 103 indicated treatment at 500 °C to allow complete removal of organic constituents within one 104 hour, critically preserving the structural and functional integrity of electrochemically active 105 materials and current collectors. This identified optimal temperature offers a crucial balance 106 between efficiency and material preservation, thereby providing practical guidance for 107 designing energy-efficient and scalable recycling processes that support the broader 108 implementation of circular economy principles for critical raw materials. 109 110 2. Materials and Methods 111 2.1 Material 112 The LIB pouch cells used in this study possess a nominal voltage of 3.65 V and a rated 113 capacity of 78 Ah. These cells were previously characterised in our previous work by 114 Pražanová et al. [32]. Each cell comprises 36 stacked layers comprising NMC622 cathode 115 materials, where the numbers indicate the molar ratio of Ni:Mn:Co, a polymer separator, and 116 graphite-based anode layers. The electrolyte consists of LiPF6 in an organic solvent, and the 117 entire assembly is encapsulated in a flexible polymer–aluminium laminated pouch. 118 Initially used in a fully electric vehicle, the battery module had a nominal voltage 119 of 29.36 V and a total energy capacity of 6.85 kWh. Before disassembly, the module was deeply 120 discharged (voltage level approximately 0 V). The module’s casing was carefully milled open 121 to access the internal cells, and the adhesive bonding was weakened by applying alcohol to 122 facilitate their separation. Subsequently, the cells were manually extracted from the opened 123 module. The open structure of the module, individual battery cells, procedure of their opening, 124 and specimen preparation and characterisation are shown in Figure 1. 125 6 126 127 Figure 1: Overview of the experimental workflow: opening of the battery module, extraction 128 and disassembly of pouch cells, preparation of specimens of battery materials, and subsequent 129 morphological and elemental analyses (scanning electron microscopy, SEM; energy-dispersive 130 X-ray spectroscopy, EDS) followed by thermal analyses (thermogravimetric analysis, TGA; 131 thermogravimetric analysis coupled with mass spectrometry, TGA-MS). 132 133 2.2 Methods 134 2.2.1 Specimen Preparation 135 A set of samples was prepared for analysis to monitor changes in morphology and 136 surface composition induced by thermal treatment. The battery cell was carefully disassembled 137 using a ceramic knife, and individual components, specifically the cathode enclosed within 138 7 the separator pouch and the anode, were isolated. All procedures were conducted inside 139 a laboratory fume hood. 140 Following disassembly, as described in Figure 1, intact electrodes and the separator 141 layers were pre-dried at ambient temperature to evaporate the carbonates. The pre-dried layers 142 were subsequently sectioned into 25 × 25 mm square samples using a precision paper cutter. 143 Afterwards, the sections were dried at 60 °C until no further decreases in mass were observed 144 (approximately one week). The final samples were weighed in porcelain crucibles using an 145 analytical balance. 146 The specimens were classified into three groups according to their functional role within 147 the cell: cathode, anode, and separator. In addition, a fourth reference group was prepared, 148 consisting of the cathode layer covered by a separator on both sides, to control potential 149 interfacial effects. This configuration deviates from the standard architecture, in which 150 separators on both sides typically enclose the cathode. Five independent replicates were 151 measured for each sample category to ensure statistical validity. 152 For the thermal degradation analyses, circular samples with a diameter of 5 mm were 153 punched from an unopened battery cell using a manual puncher. These specimens comprised 154 the entire cross-section of the battery cell, including spinel, separator, and graphite layers, and 155 are hereinafter referred to as “cross-section samples.” In addition to the full cross-section 156 samples, a separate specimen of cathode, anode, and the cathode with a two-sided separator 157 was explicitly prepared for TGA-MS measurements. 158 159 2.2.2 Material Characterisation Methods 160 Thermogravimetric Analysis 161 Thermal degradation in dynamic mode was assessed using a thermogravimetric analyser 162 (Discovery TGA550 Auto Advanced, TA Instruments, USA). A cross-section specimen, 163 8 including all electrochemically active layers with a weight of approximately 25 mg, was 164 subjected to heating from room temperature (24 °C) to 1000 °C at a constant heating rate 165 of 10 °C∙min-1 in an air atmosphere with a flow rate of 65 mL∙min-1. 166 167 Thermogravimetric Analysis – Mass Spectrometry 168 The chemical composition of degradation products was investigated using coupled 169 TGA-MS. The following sample types were analysed: cross-section, anode, cathode, and 170 cathode with one-sided separator. Measurements were performed on a TG-DTA Setsys 171 Evolution system (Setaram, France) coupled to an OmniStarTM quadrupole mass spectrometer 172 (Pfeiffer Vacuum, Germany). 173 Before thermal treatment, all samples were stabilised at 30 °C for 30 minutes. 174 Subsequently, the samples were heated in an air atmosphere at a constant heating rate 175 of 10 °C∙min-1. After the heating and thermogravimetric data acquisition were completed, the 176 samples were allowed to cool under ambient conditions, while mass spectrometric data 177 acquisition continued for an additional 50 minutes. Mass spectra were recorded up to 150 m/z 178 (mass-to-charge ratio) with a resolution of 1 m/z; each spectrum was acquired over 8 seconds, 179 corresponding to a dwell time of 53 milliseconds per m/z unit. The data obtained from TGA 180 and MS were synchronously aligned, processed, annotated, and visualised using OriginPro 181 software. Representative ions corresponding to specific compounds or chemical groups were 182 selected based on the NIST17 library of electron ionisation spectra. 183 184 Static Thermal Mass Loss Analysis 185 Samples were placed in a CLASIC laboratory furnace with a front-opening design for 186 static thermogravimetric measurements. Heating was performed at 5 °C·min-1 to target 187 temperatures of 100, 200, 300, 400, 500, 600, 700, and 800 °C, each followed by a one-hour 188 9 isothermal hold, then cooled to room temperature by natural convection overnight. The 189 relatively high heating rate and short exposure time were chosen to reduce the required time to 190 effectively obtain the studied materials, which corresponds to the study's objectives and the 191 economic demands of industrial use. This approach is relevant for pyrometallurgical 192 pretreatment in battery recycling, where energy efficiency and time optimisation are critical. 193 Temperatures were selected to identify the minimum effective recycling threshold under 194 economic constraints, focusing in detail on the 400 to 650 °C range, with measurements at 400, 195 450, 500, 550, 600, and 650 °C. 196 After cooling to ambient temperature under natural conditions, gravimetric 197 measurements were performed using a calibrated KERN analytical balance to evaluate mass 198 loss resulting from thermal exposure. Each sample type was measured in five independent 199 replicates, and the mass was recorded to four decimal places to ensure high precision. 200 This methodology enabled a comprehensive assessment of thermally induced mass changes, 201 enhancing understanding of material decomposition behaviour across various temperature 202 conditions. 203 204 Scanning Electron Microscopy 205 Following thermal exposure, the samples were subjected to structural and compositional 206 analyses to assess changes induced by heat treatment. SEM was employed to examine 207 modifications in surface morphology using a TESCAN VEGA 3 LMU scanning electron 208 microscope. Imaging was conducted at an accelerating voltage of 20 kV, a working distance of 209 15 mm, and a beam intensity of 15 nA, utilising both secondary and backscattered electrons at 210 a magnification of 2000×. 211 To complement the morphological investigation, EDS was performed to determine 212 alterations in elemental composition. Measurements were conducted using an OXFORD 213 16 collector in NMC cathodes. This degradation was found to reduce material recovery efficiency 328 and compromise the quality of recovered fractions. 329 330 3.3 Morphological and Elemental Composition Changes Analysis 331 Building upon the insights from thermal mass loss analysis, further investigation was 332 conducted into the structural and compositional stability of the cathode materials. In line with 333 the recycling objectives that prioritise the recovery of valuable metals found primarily in battery 334 cathodes [30], [40], thermally exposed cathode samples were analysed to examine their 335 morphological and structural changes using SEM and EDS. Figure 4 illustrates the 336 representative initial condition of the dried cathode before thermal treatment, along with 337 elemental maps depicting both the baseline state and the state after exposure to the highest 338 temperature achieved (800 °C). This approach was employed to evaluate the surface 339 composition of the cathode and to track the compositional changes resulting from heat treatment 340 across a temperature range of 100 to 800 °C, with increments of 100 °C. The comprehensive 341 results for all exposed cathode samples are provided in Figure 5. 342 343 Figure 4: Illustration of (a) SEM measurements for the untreated cathode sample using 344 secondary electrons imaging - left, backscattered electrons imaging - right; (b) EDS mapping 345 for the untreated cathode sample (T0) compared to the thermally treated cathode sample at 346 800 °C (T800). 'T' denotes the specific temperature at which the analysis was performed. 347 17 The findings indicate that the investigated NMC layer possesses exceptional thermal 348 stability, such that exposure to temperatures of 800 °C does not significantly alter the properties 349 of this crystalline spinel structure. However, a critical observation was the onset of melting of 350 the Al current collector at 700 °C. This melting event significantly compromises the integrity 351 of the surrounding electroactive material by causing delamination and potential encapsulation, 352 thereby diminishing the quality of the recovered NMC spinel and increasing the complexity for 353 subsequent purification. The ultimate objective of the thermal treatment process is to achieve a 354 temperature regime that maintains the original properties of the valuable electroactive materials 355 while effectively removing all organic components and facilitating their subsequent separation 356 from current collectors, supporting high-value material recovery. 357 18 358 Figure 5: Illustration of (a) SEM measurements for the cathode sample across a temperature 359 range of 100-800 °C, with increments of 100 °C, using secondary electrons imaging - left, 360 19 backscattered electrons imaging - right. 'T' denotes the specific temperature at which the 361 analysis was performed. 362 363 Complementing the morphological observations, detailed elemental analysis of the 364 thermally treated cathode surfaces was performed using EDS. The study primarily focused on 365 key electroactive elements (Ni, Mn, Co) and tracking changes in carbon and fluorine residues, 366 as presented in Figure 6. Beyond these primary targets, various other elements were identified, 367 indicative of residues originating from auxiliary battery materials, including Al (from Al2O3, 368 a separator residue [25]), P (from the decomposition of LiPF6 [12], [13]), W (traces of WO3, 369 a stabiliser in NMC spinel [41], [42]), and O (common to all oxide species [43]). Their 370 identification provided insights into potential contamination sources and the completeness of 371 organic removal following thermal treatment. It's important to note that metallic Al and Cu 372 from current collectors cannot be evaluated by surface analysis of electrodes using EDS. 373 20 374 Figure 6: EDS analysis of cathode surface composition after thermal exposure at selected 375 temperatures: (a) full range from 0 to 800 °C in 100 °C increments; (b) detailed range from 400 376 to 650 °C in 50 °C increments. ‘T’ indicates the specific temperature at which each sample was 377 analysed. 378 A critical compositional shift was observed at approximately 400 °C, manifesting as 379 a substantial reduction in organic carbon and fluorine content. These changes led to a relative 380 increase in NMC metal content (Ni, Mn, Co) due to the elimination of organic components, as 381 evident from the graphs showing a significant increase in the relative yield of target elements 382 21 from 400 °C. Notably, at 500 °C, the carbon signal was absent, confirming complete removal 383 of the organic matrix without observable degradation of the NMC phase. Further investigation 384 into narrower temperature intervals revealed that residual carbon was fully combusted even at 385 450 °C with one hour of exposure. However, complete fluorine removal was only achieved at 386 higher temperatures, approximately 700 °C, indicating the presence of more thermally stable 387 fluorine-containing compounds at 500 °C. The persistence of these fluorides at 500 °C 388 is a critical consideration, as they can complicate subsequent hydrometallurgical leaching and 389 may contribute to equipment corrosion or lower final product purity. Regarding other elements, 390 residual P from the electrolyte remained unchanged, while oxygen showed an opposite trend, 391 growing at the highest temperatures due to high-temperature oxidation. Among the identified 392 contaminants, only refractory Al2O3 and WO3 persisted throughout the entire heat treatment. 393 Despite the incomplete fluorine removal at 500 °C, this temperature was reaffirmed as optimal 394 for pyrometallurgical pre-treatment, as it effectively combines extensive organic purification 395 (especially carbon removal) with excellent preservation of the electroactive material structure 396 before significant current collector degradation. 397 The systematic analysis of electrode materials subjected to high-temperature exposure 398 for one hour across a range of temperatures from 100 to 800 °C, explicitly focusing on NMC 399 cathodes, graphite anodes, and polymeric separators, has yielded valuable insights into their 400 thermal behaviour. The most significant changes in mass and composition were consistently 401 observed between 400 and 650 °C. This comprehensive investigation underscores the suitability 402 of high-temperature pyrometallurgical approaches for recovering and recycling electroactive 403 materials from spent batteries. 404 At 100 °C, electrode materials undergo thorough drying to a constant mass. Subsequent 405 heating to 200 °C initiates the oxidation and browning of PE within the separator, alongside the 406 decomposition of PVDF binder. At 300 °C, the oxidation of the separator polymer progresses, 407 22 accompanied by the liberation of fluorine compounds. The first significant changes in relative 408 composition are observed at 400 °C, primarily marked by the onset of carbon combustion. By 409 500 °C, all organic carbon is eliminated; however, this temperature also initiates the oxidation 410 of the anodic graphite. The most pronounced oxidation of graphite on the anode occurs at 411 600 °C, while cathodic layers remain stable. Concurrently, the separator polymer decreases in 412 mass linearly with increasing temperature, and the electroactive material detaches slightly from 413 the current collector. At 700 °C, almost all graphite on the anode is oxidised, but importantly, 414 the Al current collector on the cathode begins to melt, potentially reducing the quality of the 415 NMC spinel. Even at 800 °C, where the copper current collector of the anode oxidises and 416 samples disintegrate into powder, it was demonstrated that the NMC spinel crystals largely 417 retain their characteristic structure. 418 Based on these findings, a temperature of 500 °C has been identified as optimal for the 419 pyrometallurgical separation of electroactive electrode materials. This temperature effectively 420 removes the binder and facilitates straightforward separation of electroactive materials from 421 their current collectors, which remain largely undegraded after just one hour of exposure. 422 At lower temperatures, the persistence of organic compounds from the electrolyte and binder 423 polymers significantly impedes the separation of electroactive materials and the polymeric 424 separator. Conversely, higher temperatures lead to detrimental oxidative degradation of anodic 425 graphite and metallic current collectors (Al and Cu). While the NMC spinel from the cathode 426 surface remains stable up to 800 °C, its purity and thus the efficiency of separation are 427 compromised at elevated temperatures. Although graphite oxidation at higher temperatures 428 could potentially be mitigated by heat treatment in a specialised furnace under an inert 429 atmosphere, such a process would substantially increase the cost of product recovery, and 430 residuum from organic carbon compounds might persist. Furthermore, Al, P, and W 431 contaminating compounds from the original product persist in the recovered electroactive 432 23 materials after heat treatment, suggesting a potential need for subsequent hydrometallurgical 433 purification to achieve a high-purity final product. 434 5. Conclusion 435 The thermal behaviour of key LIB components (NMC cathodes, graphite anodes, and 436 polymeric separators) was systematically examined across a comprehensive temperature range 437 of 100 to 800 °C, with a specific focus on the industrially relevant window of 400 to 650 °C. 438 Unlike prior fragmented studies, an integrated experimental approach was utilised, revealing 439 critical inter-component interactions and their impact on material integrity during low440 temperature pyrometallurgical pre-treatment. The results show that a treatment temperature of 441 500 °C offers the best balance for pyrometallurgical pre-treatment, allowing complete removal 442 of organic binders and electrolyte residues within one hour. At this temperature, electroactive 443 materials can be effectively separated from current collectors, which remain mostly intact. 444 Lower temperatures did not eliminate organic carbon compounds, complicating separation, 445 while higher temperatures led to oxidation of graphite and mechanical degradation of collectors. 446 Despite the thermal stability of NMC cathodes up to 800 °C, their purity decreases at higher 447 temperatures due to interactions with molten current collectors. The findings confirm that 448 treatment within this specific temperature range is favourable for preserving active materials 449 while enabling efficient removal of organics, thereby providing practical insight for the 450 development of energy-efficient, sustainable, and cost-effective LIB recycling processes. 451 This study, therefore, contributes to the basis of the design of thermally driven pre452 treatment strategies for EOL LIBs. By clearly defining 500 °C as a suitable operational 453 parameter, the work supports the development of energy-efficient, scalable processes that 454 minimize collector degradation and preserve the electrochemical integrity of active materials. 455 The retention of the NMC spinel structure at this temperature not only facilitates the recovery 456 of high-purity cathode material but also opens possibilities for direct re-use or simplified 457 24 downstream refining. These findings advance the understanding of low-temperature 458 pyrometallurgical processing and offer practical guidance for its implementation in industrial 459 recycling frameworks. As such, this approach supports the broader shift toward circular 460 economy practices in the field of critical raw materials management. 461 462 CRediT authorship contribution statement 463 Anna Pražanová: Resources, Methodology, Conceptualisation, Writing – Original draft, 464 Project administration. 465 Jan Kočí: Formal analysis, Data curation, Visualisation, Investigation, Writing – Original 466 draft, Writing – Review & Editing. 467 Jonáš Uřičář: Data curation, Investigation, Visualisation, Writing – Review & Editing 468 Dominik Pilnaj: Data curation, Investigation. 469 Daniel-Ioan Stroe: Supervision, Writing – Review & Editing. 470 Vaclav Knap: Supervision, Writing – Review & Editing, Funding acquisition, Project 471 administration. 472 473 Declaration of competing interest 474 All authors declare that they have no conflicts of interest. 475 476 Data availability 477 Data will be made available on request. 478 479 Acknowledgement 480 This work was financially supported by the Grant Agency of the CTU in Prague, grant No. No. 481 SGS24/136/OHK3/3T/13. Additionally, the infrastructure used was made available through the 482 25 project "The Energy Conversion and Storage", funded as project No. 483 CZ.02.01.01/00/22_008/0004617 by Programme Johannes Amos Comenius, call Excellent 484 Research. 485 486 References 487 488 [1] Y. Wang, H. Yin, L. An, Y. Wang, H. Yin, and L. An, “An Upcoming Global 489 Challenge: Efficient Recycling for End-of-Life Lithium-Ion Batteries,” Glob. 490 Challenges, vol. 6, no. 12, p. 2200184, Dec. 2022, doi: 10.1002/GCH2.202200184. 491 [2] U. Saleem, B. Joshi, and S. Bandyopadhyay, “Hydrometallurgical Routes to Close the 492 Loop of Electric Vehicle (EV) Lithium-Ion Batteries (LIBs) Value Chain: A Review,” 493 J. Sustain. Metall., vol. 9, no. 3, pp. 950–971, Sep. 2023, doi: 10.1007/S40831-023494 00718-W/FIGURES/10. 495 [3] G. Harper et al., “Recycling lithium-ion batteries from electric vehicles,” Nat. 2019 496 5757781, vol. 575, no. 7781, pp. 75–86, Nov. 2019, doi: 10.1038/s41586-019-1682-5. 497 [4] Y. Bai, N. Muralidharan, Y. K. Sun, S. Passerini, M. Stanley Whittingham, and I. 498 Belharouak, “Energy and environmental aspects in recycling lithium-ion batteries: 499 Concept of Battery Identity Global Passport,” Mater. Today, vol. 41, pp. 304–315, Dec. 500 2020, doi: 10.1016/J.MATTOD.2020.09.001. 501 [5] A. Pražanová, V. Knap, and D.-I. Stroe, “Literature Review, Recycling of Lithium-Ion 502 Batteries from Electric Vehicles, Part I: Recycling Technology,” Energies 2022, Vol. 503 15, Page 1086, vol. 15, no. 3, p. 1086, Feb. 2022, doi: 10.3390/EN15031086. 504 [6] C. Pan and Y. Shen, “Pyrometallurgical recycling of spent lithium-ion batteries from 505 conventional roasting to synergistic pyrolysis with organic wastes,” J. Energy Chem., 506 vol. 85, pp. 547–561, Oct. 2023, doi: 10.1016/J.JECHEM.2023.06.040. 507