Direct regeneration of spent LiFePO4 cathode materials assisted with a bifunctional organic lithium salt

Direct regeneration is an effective strategy of spent lithium iron phosphate (S-LFP), with the principal aspect being the selection of the lithium source and reductant. Here, assisted with a thermodynamically favourable reaction involving a bifunctional organic lithium salt (lithium citrate), the single-step regeneration of S-LFP is successfully achieved. The structure and composition of the regenerated LFP are significantly restored, demonstrating excellent electrochemical performance (142.7 mA h g-1) with no degradation after 200 cycles.

Approaching Sustainable Lithium-Ion Batteries through Voltage-Responsive Smart Prelithiation Separator with Surface-Engineered Sacrificial Lithium Agents

The surge in lithium-ion batteries has heightened concerns regarding metal resource depletion and the environmental impact of spent batteries. Battery recycling has become paramount globally, but conventional techniques, while effective at extracting transition metals like cobalt and nickel from cathodes, often overlook widely used spent LiFePO4 due to its abundant and low-cost iron content. Direct regeneration, a promising approach for restoring deteriorated cathodes, is hindered by practicality and cost issues despite successful methods like solid-state sintering. Hence, a smart prelithiation separator based on surface-engineered sacrificial lithium agents is proposed. Benefiting from the synergistic anionic and cationic redox, the prelithiation separator can intelligently release or intake active lithium via voltage regulation. The staged lithium replenishment strategy was implemented, successfully restoring spent LiFePO4's capacity to 163.7 mAh g-1 and a doubled life. Simultaneously, the separator can absorb excess active lithium up to approximately 600 mAh g-1 below 2.5 V to prevent over-lithiation of the cathode This innovative, straightforward, and cost-effective strategy paves the way for the direct regeneration of spent batteries, expanding the possibilities in the realm of lithium-ion battery recycling.

Nondisassembly Repair of Degraded LiFePO4 Cells via Lithium Restoration from the Solid Electrolyte Interphase

The disposal of degraded batteries will be a severe challenge with the expanding market demand for lithium iron phosphate (LiFePO4 or LFP) batteries. However, due to a lack of economic and technical viability, conventional metal extraction and material regeneration are hindered from practical application. Herein, we propose a nondisassembly repair strategy for degraded cells through a lithium restoration method based on deep discharge, which can elevate the anodic potential to result in the selective oxidative decomposition and thinning of the solid electrolyte interphase (SEI) on the graphite anode. The decomposed SEI acts as a lithium source to compensate for the Li loss and eliminate Li-Fe antisite defects for degraded LFP. Through this design, the repaired pouch cells show improved kinetic characteristics, significant capacity restoration, and an extended lifespan. This proposed repair scheme relying on SEI rejuvenation is of great significance for extending the service life and promoting the secondary use of degraded cells.

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.

Sustainable reprocessing of lithium iron phosphate batteries: A recovery approach using liquid-phase method at reduced temperature

Lithium iron phosphate batteries, known for their durability, safety, and cost-efficiency, have become essential in new energy applications. However, their widespread use has highlighted the urgency of battery recycling. Inadequate management could lead to resource waste and environmental harm. Traditional recycling methods, like hydrometallurgy and pyrometallurgy, are complex and energy-intensive, resulting in high costs. To address these challenges, this study introduces a novel low-temperature liquid-phase method for regenerating lithium iron phosphate positive electrode materials. By using N2H4·H2O as a reducing agent, missing Li+ ions are replenished, and anti-site defects are reduced through annealing. This process restores nearly all missing Li+ ions at 80 °C/6h. After high-temperature sintering at 700 °C/2h, the regenerated LiFePO4 matches commercial LiFePO4 in terms of anti-site defects and exhibits excellent performance with a 97 % capacity retention rate after 100 cycles at 1C. Compared to high-temperature techniques, this low-temperature liquid-phase method is simpler, safer, and more energy-efficient, offering a blueprint for reclaiming discarded LiFePO4 and similar materials.

Emerging Processes for Sustainable Li-Ion Battery Cathode Recycling

The colossal growth in the use of Li-ion batteries (LiBs) has raised serious concerns over the supply chain of strategic minerals, e.g., Co, Ni, and Li, that make up the cathode active materials (CAM). Recycling spent LiBs is an important step toward sustainability that can establish a circular economy by effectively tackling large amounts of e-waste while ensuring an unhindered supply of critical minerals. Among the various methods of LiB recycling available, pyro- and hydrometallurgy have been utilized in the industry owing to their ease of operation and high efficiency, although they are associated with significant environmental concerns. Direct recycling, a more recent concept that aims to relithiate spent LiBs without disrupting the lattice structure of the CAMs, has been realized only in the laboratory scale so far and further optimization is required before it can be extended to the bulk scale. Additionally, significant progress has been made in the areas of hydrometallurgy in terms of using ecofriendly green lixiviants and alternate sources of energy, e.g., microwave and electrochemical, that makes the recycling processes more efficient and sustainable. In this review, the latest developments in LiB recycling are discussed that have focused on environmental and economic viability, as well as process intensification. These include deep eutectic solvent based recycling, electrochemical and microwave-assisted recycling, and various types of direct recycling.

Potential-Regulated Design for Direct Recycling of Degraded LiFePO4 Cathode

The rapid proliferation of power sources equipped with lithium-ion batteries poses significant challenges in terms of post-scrap recycling and environmental impacts, necessitating urgent attention to the development of sustainable solutions. The cathode direct regeneration technologies present an optimal solution for the disposal of degraded cathodes, aiming to non-destructively re-lithiate and straightforwardly reuse degraded cathode materials with reasonable profits and excellent efficiency. Herein, a potential-regulated strategy is proposed for the direct recycling of degraded LiFePO4 cathodes, utilizing low-cost Na2SO3 as a reductant with lower redox potential in the alkaline systems. The aqueous re-lithiation approach, as a viable alternative, not only enables the re-lithiation of degraded cathode while ignoring variation in Li loss among different feedstocks but also utilizes the rapid sintering process to restore the cathode microstructure with desirable stoichiometry and crystallinity. The regenerated LiFePO4 exhibits enhanced electrochemical performance with a capacity of 144 mA h g-1 at 1 C and a high retention of 98% after 500 cycles at 5 C. Furthermore, this present work offers considerable prospects for the industrial implementation of directly recycled materials from lithium-ion batteries, resulting in improved economic benefits compared to conventional leaching methods.

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.

Enhancing Li-Ion Battery Anodes: Synthesis, Characterization, and Electrochemical Performance of Crystalline C60 Nanorods with Controlled Morphology and Phase Transition

Recently, C60 has emerged as a promising anode material for Li-ion batteries, attracting significant interest due to its excellent lithium storage capacity. The electrochemical performance of C60 as an anode is largely dependent on its internal crystal structure, which is significantly influenced by the synthesis method and corresponding conditions. However, there have been few reports on how the synthesis process affects the crystal structure and Li+ storage capacity of C60. This study used the liquid-liquid interface precipitation method and a low-temperature annealing process to fabricate one-dimensional C60 nanorods (NRs). We thoroughly investigated synthesis conditions, including the growth time, drying temperature, annealing time, and annealing atmosphere. The results demonstrate that these synthesis conditions directly impact the morphology, phase transition, and electrochemical efficiency of pure C60 NRs. Remarkably, the hexagonal close-packed structural C60 NRs-6012h, in a metastable form, exhibits a reversible Li+ storage capacity as an anode material in Li-ion batteries. Furthermore, the face-centered cubic C60 NRs-603001h electrode shows significantly enhanced rate performance and long-cycle stability. A discharge-specific capacity of 603 mAh g-1 was maintained after 2000 cycles at a current density of 2 A g-1. This study elucidates the effect of synthesis conditions on C60 crystals, offering an effective strategy for preparing high-performance C60 anode materials.

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.

Toward Direct Regeneration of Spent Lithium-Ion Batteries: A Next-Generation Recycling Method

The popularity of portable electronic devices and electric vehicles has led to the drastically increasing consumption of lithium-ion batteries recently, raising concerns about the disposal and recycling of spent lithium-ion batteries. However, the recycling rate of lithium-ion batteries worldwide at present is extremely low. Many factors limit the promotion of the battery recycling rate: outdated recycling technology is the most critical one. Existing metallurgy-based recycling methods rely on continuous decomposition and extraction steps with high-temperature roasting/acid leaching processes and many chemical reagents. These methods are tedious with worse economic feasibility, and the recycling products are mostly alloys or salts, which can only be used as precursors. To simplify the process and improve the economic benefits, novel recycling methods are in urgent demand, and direct recycling/regeneration is therefore proposed as a next-generation method. Herein, a comprehensive review of the origin, current status, and prospect of direct recycling methods is provided. We have systematically analyzed current recycling methods and summarized their limitations, pointing out the necessity of developing direct recycling methods. A detailed analysis for discussions of the advantages, limitations, and obstacles is conducted. Guidance for future direct recycling methods toward large-scale industrialization as well as green and efficient recycling systems is also provided.

All-element recovery and regeneration of mixed LiNixCoyMn1-x-yO2/LiFePO4 cathode materials by synergistic redox processes

Given the rising lithium-ion battery retirement trend, there is a pressing need for a sustainable, cost-effective, versatile, and industrially viable positive active powder reprocessing method. The current treatment methods require significant amounts of acids, reducing agents, and other additives, resulting in increased treatment expenses and detrimental environmental consequences. This paper proposes a synergistic redox strategy, based on thermodynamic calculations of potential self-promoting reactions in mixed LFP/NCM systems, for the recovery of spent LFP and NCM batteries without the need for additional agents in a milder acidic atmosphere. In this cooperative redox strategy, the spontaneous extraction and oxidation of Fe2+ to Fe3+ took place within the acidic solution atmosphere encapsulating LFP. Simultaneously, NCM underwent further reduction, yielding Ni2+ and Fe2+, thereby enabling the proficient dissolution and segregation of lithium and transition metal ions. The leaching rate of lithium, nickel, cobalt and manganese was close to 100% when the reaction was carried out at 20 °C for 40 min. The final raw material was reprepared into a battery with a capacity of 168.8 mA h g-1 at 1C, and the cycle retention rate was 76.78% after 300 cycles. Regenerating FPO into LFP cathode material achieves closed-loop recycling of all elements and generates 12% higher profits compared to separate processes. Our method proposes a zero-additive battery recycling process and successfully explains the intrinsic redox process.

Direct Regenerating Cathode Materials from Spent Lithium-Ion Batteries

Recycling cathode materials from spent lithium-ion batteries (LIBs) is critical to a sustainable society as it will relief valuable but scarce recourse crises and reduce environment burdens simultaneously. Different from conventional hydrometallurgical and pyrometallurgical recycling methods, direct regeneration relies on non-destructive cathode-to-cathode mode, and therefore, more time and energy-saving along with an increased economic return and reduced CO2 footprint. This review retrospects the history of direct regeneration and discusses state-of-the-art development. The reported methods, including high-temperature solid-state, hydrothermal/ionothermal, molten salt thermochemistry, and electrochemical method, are comparatively introduced, targeting at illustrating their underlying regeneration mechanism and applicability. Further, representative repairing and upcycling studies on wide-applied cathodes, including LiCoO2 (LCO), ternary oxides, LiFePO4 (LFP), and LiMn2 O4 (LMO), are presented, with an emphasis on milestone cases. Despite these achievements, there remain several critical issues that shall be addressed before the commercialization of the mentioned direct regeneration methods.

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.

Recycling technologies, policies, prospects, and challenges for spent batteries

The recycling of spent batteries is an important concern in resource conservation and environmental protection, while it is facing challenges such as insufficient recycling channels, high costs, and technical difficulties. To address these issues, a review of the recycling of spent batteries, emphasizing the importance and potential value of recycling is conducted. Besides, the recycling policies and strategies implemented in representative countries are summarized, providing legal and policy support for the recycling industry. Moreover, a comprehensive classification and comparison of recycling technologies identify the characteristics and current status of different approaches. The integrated recycling technology provides a better recycling performance with zero-pollution recycling of spent battery. Biorecycling technology is expected to gain a broad development prospect in the future owing to the superiority of energy-saving and environmental protection, high recycling efficiency, via microbial degradation, enzymatic degradation, etc. Consequently, as for the existing recycling challenges of waste batteries, developing new recycling technology and perfecting its recycling system is an indispensable guarantee for the sustainable development of waste battery. Meanwhile, theoretical support is offered for the recycling of spent batteries.

Electrochemical Restoration of Battery Materials Guided by Synchrotron Radiation Technology for Sustainable Lithium-Ion Batteries

Lithium-ion batteries (LIBs) have been ubiquitous in modern society, especially in the fields of electronic devices, electric vehicles and grid storage, while raising concerns about a tremendous number of spent batteries in the next five to ten years. As environmental awareness and resource security is gaining increasingly extensive attention, how to effectively deal with spent LIBs has become a challenging issue academically and industrially. Accordingly, the development of battery recycling has surfaced as a highly researched topic in the battery community. Recently, the structural and electrochemical restoration of recycled electrode materials have been proposed as a non-destructive method to save more energy and chemical agents compared with mature metallurgical methods. Such a refurbishment process of electrode materials is also regarded as a reverse process of their degradation in the working condition. Notably, synchrotron radiation technology, which is previously applied to diagnose battery degrade, has started to play major roles in gaining more insight into the structural restoration of electrode materials. Here, the contribution of synchrotron radiation technology to reveal the underlying degradation and regeneration mechanisms of LIBs cathodes is highlighted, providing a theoretical basis and guidance for the direct recycling and reuse of degraded cathodes.

Probing Hybrid LiFePO4/FePO4 Phases in a Single Olive LiFePO4 Particle and Their Recovering from Degraded Electric Vehicle Batteries

The recycling of LiFePO4 from degraded lithium-ion batteries (LIBs) from electric vehicles (EVs) has gained significant attention due to resource, environment, and cost considerations. Through neutron diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy, we revealed continuous lithium loss during battery cycling, resulting in a Li-deficient state (Li1-xFePO4) and phase separation within individual particles, where olive-shaped FePO4 nanodomains (5-10 nm) were embedded in the LiFePO4 matrix. The preservation of the olive-shaped skeleton during Li loss and phase change enabled materials recovery. By chemical compensation for the lithium loss, we successfully restored the hybrid LiFePO4/FePO4 structure to pure LiFePO4, eliminating nanograin boundaries. The regenerated LiFePO4 (R-LiFePO4) exhibited a high crystallinity similar to the fresh counterpart. This study highlights the importance of topotactic chemical reactions in structural repair and offers insights into the potential of targeted Li compensation for energy-efficient recycling of battery electrode materials with polyanion-type skeletons.

A Critical Review on the Recycling Strategy of Lithium Iron Phosphate from Electric Vehicles

Electric vehicles (EVs) are one of the most promising decarbonization solutions to develop a carbon-negative economy. The increasing global storage of EVs brings out a large number of power batteries requiring recycling. Lithium iron phosphate (LFP) is one of the first commercialized cathodes used in early EVs, and now gravimetric energy density improvement makes LFP with low cost and robustness popular again in the market. Developments in LFP recycling techniques are in demand to manage a large portion of the EV batteries retired both today and around ten years later. In this review, first the operation and degradation mechanisms of LFP are revisited aiming to identify entry points for LFP recycling. Then, the current LFP recycling methods, from the pretreatment of the retired batteries to the regeneration and recovery of the LFP cathode are summarized. The emerging direct recovery technology is highlighted, through which both raw material and the production cost of LFP can be recovered. In addition, the current issues limiting the development of the LIBs recycling industry are presented and some ideas for future research are proposed. This review provides the theoretical basis and insightful perspectives on developing new recycling strategies by outlining the whole-life process of LFP.

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.

Environmentally friendly method for efficiently recycling LiMn2O4 cathode materials

An environmentally friendly stripping strategy and improved electrochemical performance of spent lithium manganate materials are provided.

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.

Pneumatic separation for crushed spent lithium-ion batteries

Pneumatic separation was used to separate the valuable current collectors and harmful separators in spent lithium-ion batteries (LIBs) to avoid the plastic pollution caused by the separators in this study. Theoretical calculations for suspension velocities of the current collectors and separators indicate that they could be separated under special conditions. Furthermore, a special Z-shaped pneumatic separator was used to separate the current collectors and separators for the first time. Experiments for manually cut samples indicate that the efficiency of pneumatic separation is approximately 100% with the sizes and airflow velocities in the range of 3-4 cm and 6.96-7.8 m/s, respectively. Furthermore, industrial experiments of pneumatic separation indicate that the recoveries of the current collectors and separators are approximately 99.23% and 98.64%, respectively. Computer simulations of the separation process indicate that the turbulence and the changes in high-speed zones in the pneumatic separator benefit the separation of current collectors and separators. In conclusion, pneumatic separation is a promising technology to separate crushed current collectors and separators.