Separation of the cathode materials from the Al foil in spent lithium-ion batteries by cryogenic grinding

Fundamentals of the recycling of spent lithium-ion batteries

This review discusses the critical role of fundamentals of battery recycling in addressing the challenges posed by the increasing number of spent lithium-ion batteries (LIBs) due to the widespread use of electric vehicles and portable electronics, by providing the theoretical basis and technical support for recycling spent LIBs, including battery classification, ultrasonic flaw detection, pretreatment (e.g., discharging, mechanical crushing, and physical separation), electrolyte recovery, direct regeneration, and theoretical calculations and simulations. Physical chemistry principles are essential for achieving effective separation of different components through methods like screening, magnetic separation, and flotation. Electrolyte recovery involves separation and purification of electrolytes through advanced physical and chemical techniques. Direct regeneration technology restores the structure of electrode materials at the microscopic scale, requiring precise control of the physical state and crystal structure of the material. Physical processes such as phase changes, solubility, and diffusion are fundamental to techniques like solid-state sintering, eutectic-salt treatment, and hydrothermal methods. Theoretical calculations and simulations help predict the behaviour of materials during recycling, guiding process optimization. This review provides insights into understanding and improving the recycling process, emphasizing the central role of physical chemistry principles in addressing environmental and energy issues. It is valuable for promoting innovation in spent LIB recycling processes and is expected to stimulate interest among researchers and manufacturers.

Mechanical methods for materials concentration of lithium iron phosphate (LFP) cells and product potential evaluation for recycling

The production and sales of lithium-ion batteries (LIB) are rapidly expanding nowadays, causing a significant impact on the consumption of critical raw materials, such as lithium. Thus, developing and improving methods for the separation and recovery of materials from LIBs is necessary to ensure the supply of critical raw materials, as well as to meet the recycling targets set by some countries. This study evaluated and compared two mechanical routes to concentrate materials of LiFePO4 (LPF) cells. In addition, the economic, environmental, and scarcity risk potential of the products obtained through the best mechanical route were evaluated. The first route involved 6 grinding cycles in a knife mill, followed by particle size separation into 3 fractions. The second route involved a single grinding cycle (knife and hammer mill were tested), followed by particle size separation into 6 fractions. The second route showed more promise, with obtaining fractions rich in (1) iron, (2) aluminum and copper, and (3) cathode materials. Additionally, less operating time and energy consumption were necessary. The hammer mill offered a better separation for the iron and the cathodic materials (LiFePO4), while the knife mill proved to be more effective in concentrating the aluminum and copper. The product potential evaluation of the best route revealed that the priority fractions for recycling in economic and environmental assessment in LFP2 are 2 < n < 9.5 mm (due Cu and Al) and n < 0.5 mm (due Li). Considering the scarcity risk, priority should be assigned to the recycling of the fraction n < 0.5 due to lithium.

Comprehensive review and comparison on pretreatment of spent lithium-ion battery

Pretreatment, the initial step in recycling spent lithium-ion batteries (LIBs), efficiently separates cathode and anode materials to facilitate key element recovery. Despite brief introductions in existing research, a comprehensive evaluation and comparison of processing methods is lacking. This study reviews 346 references on LIBs recycling, analyzing pretreatment stages, treatment conditions, and method effects. Our analysis highlights insufficient attention to discharge voltage safety and environmental impact. Mechanical disassembly, while suitable for industrial production, overlooks electrolyte recovery and complicates LIBs separation. High temperature pyrolysis flotation offers efficient separation of mixed electrode materials, enhancing mineral recovery. We propose four primary pretreatment processes: discharge, electrolyte recovery, crushing and separation, and electrode material recovery, offering simplified, efficient, green, low-cost, and high-purity raw materials for subsequent recovery processes.

Chemical-Free Recycling of Cathode Material and Aluminum Foil from Waste Lithium-Ion Batteries by Combining Plasma and Ultrasonic Technology

With the rapid demand for lithium-ion batteries due to the widespread application of electric vehicles, a significant amount of battery electrode pieces requiring urgent treatment are generated during battery production and disposal. The strong bonding caused by the presence of binders makes it challenging to achieve thorough separation between the cathode active materials and Al foil, posing difficulties in efficient battery material recycling. To address this issue, a plasma-ultrasonically combined physical separation method is proposed in this study. This method utilizes plasma-generated excited-state radicals assisted by ultrasonic waves to separate active materials and current collectors. The results indicate that the binders are effectively decomposed under plasma treatment at 13.56 MHz, 100 W, and 10 min in an oxygen atmosphere, resulting in a separation efficiency of 96.8 wt % for the cathode materials. Characterization results demonstrate that the morphology, crystal structure, and chemical composition of the recycled cathode active materials remain unchanged, facilitating subsequent direct restoration and hydrometallurgical recycling. Simultaneously, the Al foil is also completely recycled for subsequent reuse. Compared with traditional methods of separating cathode active materials and aluminum foil, the method proposed in this study has significant economic and environmental potential. It can promote the recycling of battery materials and the development of sustainable transportation.

Direct Regeneration of Spent Lithium-Ion Battery Cathodes: From Theoretical Study to Production Practice

Direct regeneration method has been widely concerned by researchers in the field of battery recycling because of its advantages of in situ regeneration, short process and less pollutant emission. In this review, we firstly analyze the primary causes for the failure of three representative battery cathodes (lithium iron phosphate, layered lithium transition metal oxide and lithium cobalt oxide), targeting at illustrating their underlying regeneration mechanism and applicability. Efficient stripping of material from the collector to obtain pure cathode material has become a first challenge in recycling, for which we report several pretreatment methods currently available for subsequent regeneration processes. We review and discuss emphatically the research progress of five direct regeneration methods, including solid-state sintering, hydrothermal, eutectic molten salt, electrochemical and chemical lithiation methods. Finally, the application of direct regeneration technology in production practice is introduced, the problems exposed at the early stage of the industrialization of direct regeneration technology are revealed, and the prospect of future large-scale commercial production is proposed. It is hoped that this review will give readers a comprehensive and basic understanding of direct regeneration methods for used lithium-ion batteries and promote the industrial application of direct regeneration technology.

Selective Recovery of Cathode Materials from Spent Lithium-Ion Battery Material with a Near-Room-Temperature Separation

Effective separation of cathode materials from the current collector is a critical step in recycling a spent lithium-ion battery (LIB). This typically necessitates the decomposition or dissolution of the organic binder, poly(vinylidene fluoride) (PVDF), to achieve efficient recovery of cathode materials. However, this process requires a high decomposition temperature, typically between 400 and 600 °C, and can lead to side reactions, such as current collector oxidation/brittleness, decomposition of cathode materials, and formation of metal fluorides. In this study, we propose that non-thermal plasma (NTP) treatment can be used to achieve an extremely high separation of cathode materials and aluminum current collector at near room temperature. Instead of relying on PVDF decomposition, which requires high temperatures, PVDF can be deactivated by partially breaking down long molecular chains with appropriate NTP conditions. With a total treatment time of around 2000 s and an environmental temperature of approximately 80 °C, minor side reactions can be avoided. The separation rate can reach up to 95.69%, and high-quality cathode materials can be obtained with only 0.02 wt % aluminum impurity content. This research could potentially offer a new approach toward minimizing recycling steps and reducing energy consumption in the recycling of spent LIBs. It could also be extended to the recovery of a broader range of electronic wastes.

Challenges in Recycling Spent Lithium-Ion Batteries: Spotlight on Polyvinylidene Fluoride Removal

In the recycling of retired lithium-ion batteries (LIBs), the cathode materials containing valuable metals should be first separated from the current collector aluminum foil to decrease the difficulty and complexity in the subsequent metal extraction. However, strong the binding force of organic binder polyvinylidene fluoride (PVDF) prevents effective separation of cathode materials and Al foil, thus affecting metal recycling. This paper reviews the composition, property, function, and binding mechanism of PVDF, and elaborates on the separation technologies of cathode material and Al foil (e.g., physical separation, solid-phase thermochemistry, solution chemistry, and solvent chemistry) as well as the corresponding reaction behavior and transformation mechanisms of PVDF. Due to the characteristic variation of the reaction systems, the dissolution, swelling, melting, and degradation processes and mechanisms of PVDF exhibit considerable differences, posing new challenges to efficient recycling of spent LIBs worldwide. It is critical to separate cathode materials and Al foil and recycle PVDF to reduce environmental risks from the recovery of retired LIBs resources. Developing fluorine-free alternative materials and solid-state electrolytes is a potential way to mitigate PVDF pollution in the recycling of spent LIBs in the EV era.

Progress, Key Issues, and Future Prospects for Li-Ion Battery Recycling

The overuse and exploitation of fossil fuels has triggered the energy crisis and caused tremendous issues for the society. Lithium-ion batteries (LIBs), as one of the most important renewable energy storage technologies, have experienced booming progress, especially with the drastic growth of electric vehicles. To avoid massive mineral mining and the opening of new mines, battery recycling to extract valuable species from spent LIBs is essential for the development of renewable energy. Therefore, LIBs recycling needs to be widely promoted/applied and the advanced recycling technology with low energy consumption, low emission, and green reagents needs to be highlighted. In this review, the necessity for battery recycling is first discussed from several different aspects. Second, the various LIBs recycling technologies that are currently used, such as pyrometallurgical and hydrometallurgical methods, are summarized and evaluated. Then, based on the challenges of the above recycling methods, the authors look further forward to some of the cutting-edge recycling technologies, such as direct repair and regeneration. In addition, the authors also discuss the prospects of selected recycling strategies for next-generation LIBs such as solid-state Li-metal batteries. Finally, overall conclusions and future perspectives for the sustainability of energy storage devices are presented in the last chapter.

Applications of crushing and grinding-based treatments for typical metal-containing solid wastes: Detoxification and resource recovery potentials

Metal-containing solid wastes can induce serious environmental pollution if managed improperly, but contain considerable resources. The detoxification and resource recoveries of these wastes are of both environmental and economic significances, being indispensable for circular economy. In the past decades, attempts have been made worldwide to treat these wastes. Crushing and grinding-based treatments have been increasingly applied, the operating apparatus and parameters of which depend on the waste type and treatment purpose. Based on the relevant studies, the applications of crushing and grinding on four major types of solid wastes, namely spent lithium-ion batteries (LIBs) cathode, waste printed circuit boards (WPCBs), incineration bottom ash (IBA), and incineration fly ash (IFA) are here systematically reviewed. These types of solid wastes are generated in increasing amounts, and have the potentials to release various organic and inorganic pollutants. Despite of the widely different texture, composition, and other physicochemical properties of the solid wastes, crushing and grinding have been demonstrated to be universally applicable. For each of the four wastes, the technical route that involving crushing and grinding is described with the advantages highlighted. The crushing and grinding serve either mainstream or auxiliary role in the processing of the solid wastes. This review summarizes and highlights the developments and future directions of crushing and grinding-based treatments.

Selective Extraction of Transition Metals from Spent LiNix Coy Mn1-x-y O2 Cathode via Regulation of Coordination Environment

The complexity of chemical compounds in lithium-ion batteries (LIBs) results in great difficulties in the extraction of multiple transition metals, which have similar physicochemical characteristics. Here, we propose a novel strategy for selective extraction of nickel, cobalt, and manganese from spent LiNi_x Co_y Mn_1-x-y O₂ (NCM) cathode through the regulation of coordination environment. Depending on adjusting the composition of ligand in transition metal complexes, a tandem leaching and separation system is designed and finally enables nickel, cobalt, and manganese to enrich in the form of NiO, Co₃ O₄ , and Mn₃ O₄ with high recovery yields of 99.1 %, 95.1 %, and 95.3 %, respectively. We further confirm that the combination of different transition metals with well-designed ligands is the key to good selectivity. Through our work, fine-tuning the coordination environment of metal ions is proved to have great prospects in the battery recycling industry.

Recycling of LiFePO4 cathode materials from spent lithium-ion batteries through ultrasound-assisted Fenton reaction and lithium compensation

Efficient exfoliation of cathode materials from current collectors for their direct regeneration is the typical bottleneck during spent lithium ion batteries (LIBs) recycling due to the strong adhesion of PVDF (polyvinylidene fluoride) binders. Ultrasound-assisted Fenton reaction was innovatively applied for the selective removal of PVDF binders to recover cathode materials of LiFePO₄ from current collectors and the recovered LiFePO₄ was regenerated through lithium compensation, targeting for the in-situ recycling of cathode materials from spent LIBs. Experimental results suggest that the PVDF binders were adequately degraded by hydroxyl radical (·OH) generated from Fenton's reagent with reinforcement of ultrasound, and about 97% cathode materials can be scrubbed from Al foils under optimized conditions. Detailed analytical results support that the cathode materials peeled off from current collectors are free from contamination of effluent, and the recovered LiFePO₄ can be directly re-fabricated as new cathode materials through lithium compensation with little reduction of electrochemical performances. And the tentative mechanism investigation for pathway of ·OH generation and chemical reactions indicates that ·OH generated from Fenton's reagent with the reinforcement of ultrasound can effectively degrade PVDF binders. This work can be a green and efficient candidate for the in-situ recycling of cathode materials of LiFePO₄ from spent LIBs.

A review on the recycling of spent lithium-ion batteries (LIBs) by the bioleaching approach

This review discusses the latest trend in recovering valuable metals from spent lithium-ion batteries (LIBs) to meet the technological world's critical metal demands. Spent LIBs are a secondary source of valuable metals such as Li (5%-7%), Ni (5%-10%), Co (5%-25%), Mn (5-11%), and non-metal graphite. Recycling is essential for the battery industry to extract valuable critical metals from secondary sources to develop new and novel high-tech LIBs for various applications such as eco-friendly technologies, renewable energy, emission-free electric vehicles, and energy-saving lightings. LIB waste is currently undergoing high-temperature pyrometallurgical or hydrometallurgical processes to recover valuable metals, and these processes have proven to be successful and feasible. These methods, however, are not preferable due to the difficulties in controlling the process, secondary waste produced, high operational cost, and high risk of scaling up. Biotechnological approaches can be promising alternatives to pyrometallurgical and hydrometallurgical technologies in metal recovery from LIB waste. Microbiological metal dissolution or bioleaching has gained popularity for metal extraction from ores, concentrates, and recycled or residual materials in recent years. This technology is eco-friendly, safe to handle, and reduces operating costs and energy demands. The pre-treatment process (material preparation), microorganisms used in the bioleaching of LIBs, factors influencing the bioleaching process, methods of enhancing the leaching efficiency, regeneration of electrode materials, and future aspects have been discussed in detail.

Separation of cathode particles and aluminum current foil in lithium-ion battery by high-voltage pulsed discharge Part II: Prospective life cycle assessment based on experimental data

This series of papers addresses the recycling of cathode particles and aluminum (Al) foil from positive electrode sheet (PE sheet) dismantled from spent lithium-ion batteries (LIBs) by applying a high-voltage pulsed discharge. As concluded in Part I of the series (Tokoro et al., 2021), cathode particles and Al foil were separated in water based on a single pulsed power application. This separation of LIB components by pulsed discharge was examined by means of prospective life cycle assessment and is expected to have applications in LIB reuse and recycling. The indicators selected were life cycle greenhouse gas (LC-GHG) emissions and life cycle resource consumption potential (LC-RCP). We first completed supplementary experiments to collect redundant data under several scale-up circumstances, and then attempted to quantify the uncertainties from scaling up and progress made in battery technology. When the batch scale of pulsed discharge separation is sufficiently large, the recovery of cathode particles and Al foil from PE sheet by pulsed discharge can reduce both LC-GHG and LC-RCP, in contrast to conventional recycling with roasting processes. Due to technology developments in LIB cathodes, the reuse of positive electrode active materials (PEAM) does not always have lower environmental impacts than the recycling of the raw materials of PEAM in the manufacturing of new LIB cathodes. This study achieved a proof of concept for resource consumption reduction induced by cathode utilization, considering LC-GHG and LC-RCP, by applying high-voltage pulsed discharge separation.

Hydrometallurgical enhanced liberation and recovery of anode material from spent lithium-ion batteries

The efficient recycling of spent anode material (SAM) from spent lithium-ion batteries (LIBs) is generally critical in terms of electronic waste recyclingas well as increasing resource shortage and environmental problems. This research reported a novel and green method to recycle lithium, copper foil, and graphite from SAM by water leaching treatment. The results indicated that 100% of graphite was exfoliated from the anode material and 92.82% leaching efficiency of lithium was obtained under the optimal conditions of 80 °C, 60 g/L, 300 rpm, and 60 min, respectively. This finding revealed that the SAM got a full liberation characteristic due to the removal of binder, which produced an ideal leaching lithium efficiency rivaling the acids' performance. The mechanism of the liberation of SAM and lithium leaching is presented based on the analysis of results. The graphite was purified and recovered after water leaching treatment. Besides, lithium was recovered in the form of lithium carbonate (Li₂CO₃)_, and the copper foil was recovered in a sheet. This study endeavors to develop an economical and environmentally feasible plan to recycle graphite, copper, and lithium from SAM.

Separation of cathode particles and aluminum current foil in Lithium-Ion battery by high-voltage pulsed discharge Part I: Experimental investigation

To enable effective reuse and recycling processes of spent lithium-ion batteries (LiBs), here we develop a novel electrical method based on a high-voltage pulsed discharge to separate cathode particles and aluminum (Al) foil. A cathode particle sample was mechanically separated from a LiB, cut into 30-mm × 80-mm test pieces, and subjected to a high-voltage electrical pulse discharge from either end in water. At a voltage of 25 kV, 93.9% of the cathode particles separated from the Al foil. These particles were easily recovered by sieving at 2.36 mm because the Al foil retained its shape. Some Al contaminated the particles owing to generation of hot plasma and subsequent shock waves; however, the Al concentration in the recovered cathode particles was limited to 2.95%, which is low enough to allow for further cobalt and nickel recovery by hydrometallurgical processing. The results of heat balance calculations obtained from the current waveforms suggested that polyvinylidene fluoride, the main component of the adhesive in the cathode particle layers, melted and lost its adhesion through Joule heating of the Al foil at the maximum current of 19.0 kA at 25 kV. Almost 99% of the recovered cathode particles maintained their chemical composition and form after separation, and therefore could potentially be directly reused in LiBs.