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

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.

Physicochemical reactions in e-waste recycling

Electronic waste (e-waste) recycling is becoming a global concern owing to its immense quantity, hazardous character and the potential loss of valuable metals. The many processes involved in e-waste recycling stem from a mixture of physicochemical reactions, and understanding the principles of these reactions can lead to more efficient recycling methods. In this Review, we discuss the principles behind photochemistry, thermochemistry, mechanochemistry, electrochemistry and sonochemistry for metal recovery, polymer decomposition and pollutant elimination from e-waste. We also discuss how these processes induce or improve reaction rates, selectivity and controllability of e-waste recycling based on thermodynamics and kinetics, free radicals, chemical bond energy, electrical potential regulation and more. Lastly, key factors, limitations and suggestions for improvements of these physicochemical reactions for e-waste recycling are highlighted, wherein we also indicate possible research directions for the future.

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.

Toward Circular Energy: Exploring Direct Regeneration for Lithium-Ion Battery Sustainability

Lithium-ion batteries (LIBs) are rapidly developing into attractive energy storage technologies. As LIBs gradually enter retirement, their sustainability is starting to come into focus. The utilization of recycled spent LIBs as raw materials for battery manufacturing is imperative for resource and environmental sustainability. The sustainability of spent LIBs depends on the recycling process, whereby the cycling of battery materials must be maximized while minimizing waste emissions and energy consumption. Although LIB recycling technologies (hydrometallurgy and pyrometallurgy) have been commercialized on a large scale, they have unavoidable limitations. They are incompatible with circular economy principles because they require toxic chemicals, emit hazardous substances, and consume large amounts of energy. The direct regeneration of degraded electrode materials from spent LIBs is a viable alternative to traditional recycling technologies and is a nondestructive repair technology. Furthermore, direct regeneration offers advantages such as maximization of the value of recycled electrode materials, use of sustainable, nontoxic reagents, high potential profitability, and significant application potential. Therefore, this review aims to investigate the state-of-the-art direct LIB regeneration technologies that can be extended to large-scale applications.

Dynamic Li+ Capture through Ligand-Chain Interaction for the Regeneration of Depleted LiFePO4 Cathode

After application in electric vehicles, spent LiFePO4 (LFP) batteries are typically decommissioned. Traditional recycling methods face economic and environmental constraints. Therefore, direct regeneration has emerged as a promising alternative. However, irreversible phase changes can significantly hinder the efficiency of the regeneration process owing to structural degradation. Moreover, improper storage and treatment practices can lead to metamorphism, further complicating the regeneration process. In this study, a sustainable recovery method is proposed for the electrochemical repair of LFP batteries. A ligand-chain Zn-complex (ZnDEA) is utilized as a structural regulator, with its ─NH─ group alternatingly facilitating the binding of preferential transition metal ions (Fe3+ during charging and Zn2+ during discharging). This dynamic coordination ability helps to modulate volume changes within the recovered LFP framework. Consequently, the recovered LFP framework can store more Li-ions, enhance phase transition reversibility between LFP and FePO4 (FP), modify the initial Coulombic efficiency, and reduce polarization voltage differences. The recovered LFP cells exhibit excellent capacity retention of 96.30% after 1500 cycles at 2 C. The ligand chain repair mechanism promotes structural evolution to facilitate ion migration, providing valuable insights into the targeted ion compensation for environmentally friendly recycling in practical applications.

Designing functional Li2CuO2-coated separators from Cu foil towards spent LiFePO4 cathode regeneration

A chemical-physical investigation proved that the loss of active Li represents the main mechanism of capacity-fading in spent LiFePO4. Given this, functional Li2CuO2-coated separators were fabricated from spent Cu foil and found to contribute to the regeneration of spent LiFePO4 in a full-cell system. This study presents a novel method for cathode/Cu foil recovery.

A comprehensive review of emerging technologies for recycling spent lithium-ion batteries

Along with the increasing demand for lithium-ion batteries (LIB), the need for recycling major components such as graphite and different critical materials contained in LIB is also reaching a peak in the research community. Several authors review the different LIB recycling methodologies, including pyro- and hydrometallurgy processes. However, the characteristics, main stages, and achievements of LIB emerging recycling are still missing. This study reviews the diverse emerging approaches for recycling critical materials from spent LIB in the last five years. A classification for emerging recycling technologies is provided, including terms like development stage and eco-friendly status. The main stages of recycling LIB are opening, phase separation, and materials recovery. Among the emerging proposals with the highest industrialization potential are direct recycling techniques due to low costs and simple procedures. Concerning phase separation, froth flotation and ultrasound-assisted methods are discussed. The former divides black mass into pure anodic and cathodic materials, while ultrasonication is employed to physically detach active materials from foils or enhance binder degradation. As to materials recovery, several recent approaches show high recovery efficiency for different elements, mainly in leaching. The use of new organic acids, deep eutectic acids, and some salts are worth noting as leaching agents due to their low environmental impact. In addition, leaching methods assisted by ultrasound and microwave irradiation increase valuable metal recovery, reducing time consumption and the number of leaching reactants. As a part of the hydrometallurgy process, metallic ion purification is performed by solvent extraction and ion exchange, while selective precipitation can be achieved by specific chemical agents or electrochemical processes.

A review on the recycling of spent lithium iron phosphate batteries

Lithium iron phosphate (LFP) batteries have gained widespread recognition for their exceptional thermal stability, remarkable cycling performance, non-toxic attributes, and cost-effectiveness. However, the increased adoption of LFP batteries has led to a surge in spent LFP battery disposal. Improper handling of waste LFP batteries could result in adverse consequences, including environmental degradation and the mismanagement of valuable secondary resources. This paper presents a comprehensive examination of waste LFP battery treatment methods, encompassing a holistic analysis of their recycling impact across five dimensions: resources, energy, environment, economy, and society. The recycling of waste LFP batteries is not only crucial for reducing the environmental pollution caused by hazardous components but also enables the valuable components to be efficiently recycled, promoting resource utilization. This, in turn, benefits the sustainable development of the energy industry, contributes to economic gains, stimulates social development, and enhances employment rates. Therefore, the recycling of discarded LFP batteries is both essential and inevitable. In addition, the roles and responsibilities of various stakeholders, including governments, corporations, and communities, in the realm of waste LFP battery recycling are also scrutinized, underscoring their pivotal engagement and collaboration. Notably, this paper concentrates on surveying the current research status and technological advancements within the waste LFP battery lifecycle, and juxtaposes their respective merits and drawbacks, thus furnishing a comprehensive evaluation and foresight for future progress.

Fundamentals, status and challenges of direct recycling technologies for lithium ion batteries

Advancement in energy storage technologies is closely related to social development. However, a significant conflict has arisen between the explosive growth in battery demand and resource availability. Facing the upcoming large-scale disposal problem of spent lithium-ion batteries (LIBs), their recycling technology development has become key. Emerging direct recycling has attracted widespread attention in recent years because it aims to 'repair' the battery materials, rather than break them down and extract valuable products from their components. To achieve this goal, a profound understanding of the failure mechanisms of spent LIB electrode materials is essential. This review summarizes the failure mechanisms of LIB cathode and anode materials and the direct recycling strategies developed. We systematically explore the correlation between the failure mechanism and the required repair process to achieve efficient and even upcycling of spent LIB electrode materials. Furthermore, we systematically introduce advanced in situ characterization techniques that can be utilized for investigating direct recycling processes. We then compare different direct recycling strategies, focussing on their respective advantages and disadvantages and their applicability to different materials. It is our belief that this review will offer valuable guidelines for the design and selection of LIB direct recycling methods in future endeavors. Finally, the opportunities and challenges for the future of battery direct recycling technology are discussed, paving the way for its further development.

Construction of a Preoxidation and Cation Doping Regeneration Strategy to Improve Rate Performance Recycling Spent LiFePO4 Materials

Efficient recycling of spent lithium-ion batteries (LIBs) is significant for solving environmental problems and promoting resource conservation. Economical recycling of LiFePO4 (LFP) batteries is extremely challenging due to the inexpensive production of LFP. Herein, we report a preoxidation combine with cation doping regeneration strategy to regenerate spent LiFePO4 (SLFP) with severely deteriorated. The binder, conductive agent, and residual carbon in SLFP are effectively removed through preoxidation treatment, which lays the foundation for the uniform and stable regeneration of LFP. Mg2+ doping is adopted to promote the diffusion efficiency of lithium ions, reduces the charge-transfer impedance, and further improves the electrochemical performance of the regenerated LFP. The discharge capacity of SLFP with severe deterioration recovers successfully from 43.2 to 136.9 mA h g-1 at 0.5 C. Compared with traditional methods, this technology is simple, economical, and environment-friendly. It provided an efficient way for recycling SLFP materials.

Novel strategy towards in-situ recycling of valuable metals from spent lithium-ion batteries through endogenous advanced oxidation process

Efficient and sustainable recycling of metal resources from spent lithium-ion batteries (LIBs) is critical for the metal resources security and environment protection. However, the intact exfoliation of cathode materials (CMs) from current collectors (Al foils) and selective extraction of Li towards the in-situ and sustainable recycling of cathodes from spent LIBs are still pending issues. A self-activated and ultrasonic-induced endogenous advanced oxidation process (EAOP) was proposed in this study for selective removal of PVDF and in-situ extraction of Li from CMs of waste LiFePO₄ (LFP) to address the above issues. Over 99 wt% CMs can be detached from Al foils after EAOP treatment under the optimized operation conditions. High purity of Al foil can be directly recycled as metallic forms and nearly 100 % of Li can be in-situ extracted from the detached CMs and then recovered as Li₂CO₃ (>99.9 % in purity). With induction and reinforcement of ultrasonic, S₂O₈^2- was self-activated by LFP to generate an increased amount of SO₄^•- radicals that will attack the PVDF binders to ensure their degradation. The degradation pathway of PVDF and density functional theory (DFT) calculation can also support the analytical and experimental results. Then, the complete and in-situ ionization of Li can be achieved by the further oxidization of SO₄^•- radicals from LFP powders. This work provides a novel strategy towards efficient and in-situ recycling of valuable metals from spent LIBs with minimized environmental footprint.

Ultra-fast recovery of cathode materials from spent LiFePO4 lithium-ion batteries by novel electromagnetic separation technology

The separation of electrode materials from current collectors plays a significant role in determining the leaching efficiency of different metals from spent lithium-ion batteries (LIBs). In the presented research, a highly efficient, environmentally sustainable, and cost-effective cathode materials separation strategy was proposed for spent LiFePO₄ batteries. Based on the difference in the thermal expansion coefficient of the binder and aluminum foil, the electromagnetic induction system was examined to harvest cathode materials for the first time, which could provide a high heating rate to erase the mechanical interlocking force between Al foil and coated material, and breaking the chemical bond or Van der Waals forces of the binder. The process avoids the usage of any chemicals such as acids and alkalis, thus eliminating the emission of wastewater. Our system shows ultra-fast separation (3 min) and achieves high-purity of recovered electrode materials and Al foils (99.6% and 99.2%). Furthermore, the morphology and crystalline structure of delaminated electrode materials remain almost the same compared with the pristine materials, which provides a previously unexplored technology to realize sustainable spent battery recycling.

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.

Direct regeneration of waste LiFePO4 cathode materials with a solid-phase method promoted by activated CNTs

Annually increasing electric vehicles will undoubtedly end in tremendous amount of waste LiFePO₄ (LFP) batteries. In this work, a highly-efficient and easy-going solid-phase method is proposed for direct regeneration of the waste LFP cathode material (W-LFP). The W-LFP is successfully regenerated via heat treatment with the addition of Li₂CO₃, CNTs and glucose. After activation, the dispersibility of CNTs in water is improved, making it easier to mix well with other materials. Also, the hydroxyl and carboxyl groups on CNTs have a certain degree of reducibility, which is conducive to the reduction of Fe³⁺ to Fe²⁺. After subsequent heat treatment, the three-dimensional conductive network composed of CNTs greatly enhances the conductivity and the ionic diffusion coefficient of LFP, thereby improving its electrochemical performance. Meanwhile, the decay and regeneration mechanisms of LFP are investigated by characterization and electrochemical testing. The regenerated LFP achieves an excellent specific capacity of 155.47 mAh/g at 0.05 C, which is around 99% that of new LFP. Additionally, the costs of main consumption in the regeneration process only account for 33.7% the price of new LFP. This low-cost, high-value-added and solid-phase direct regeneration process is proved to have great economic and energy-saving potential, which is promising for recycling the waste LFP cathode materials.

Aluminum separation by sulfuric acid leaching-solvent extraction from Al-bearing LiFePO4/C powder for recycling of Fe/P

Recovery of battery-grade FePO₄ from Al-bearing spent LiFePO₄ batteries (LFPs) is important for both prevention of environmental pollution and recycling of resources for LFPs industries. The premise for FePO₄ recovery from spent LFPs is the separation of Al, because Al readily co-precipitates with FePO₄ and lowers the electrochemical performance of the regenerated LiFePO₄. In this work, an efficient approach involving sulfuric acid leaching followed by solvent extraction was developed to separate Al from spent LiFePO₄/C powder. Di-(2-ethylhexyl) phosphoric acid (D2EHPA) in sulfonated kerosene was used as the extractant. The results showed that 96.4% of aluminum was extracted while the loss of iron was only 1.1% under the optimal conditions. The mass fraction of Al in the iron phosphate obtained from the extraction raffinate was only 0.007%, meeting the standard for preparing battery-grade FePO₄. The extracted Al can be easily stripped by diluted H₂SO₄ solution and the extractants can be reused. Additionally, slope analysis method, FTIR spectroscopy, and ESI-MS analysis revealed that the extraction of Al in D2EHPA can be ascribed to the ion exchange between hydrogen ion of -PO(OH) and Al³⁺. This work may provide an economically feasible method for the recycling of valuable components from spent Al-bearing LiFePO₄/C powder.

Recovery of Lithium Iron Phosphate by Specific Ultrasonic Cavitation Parameters

With the widespread use of lithium iron phosphate batteries in various industries, the amount of waste lithium iron phosphate batteries is also increasing year by year, and if not disposed of in a timely manner, will pollute the environment and waste a lot of metal resources. In the composition of lithium iron phosphate batteries, the cathode has an abundance of elements. The ultrasonic method is a crucial method to recover waste LiFePO4 batteries. It has the following disadvantages, such as the lack of empirical parameters and suitable research equipment. In order to overcome the inefficiency of the LiFePO4 recycling method, the airborne bubble dynamical mechanism of ultrasound in the removal of lithium phosphate cathode material was studied by a high-speed photographic observation and Fluent simulation and the disengagement process. Mainly aimed at the parameters such as action time, power, frequency, and action position in the detachment process were optimized. The recovery efficiency of lithium iron phosphate reached 77.7%, and the recovered lithium iron phosphate powder has good electrochemical properties, with the first charge–discharge ratio of up to 145 (mAh)/g. It is shown that the new disengagement process established in this study was adopted for the recovery of waste LiFePO4.