Recycling lithium-ion batteries from electric vehicles

Enhancing CA-based separators with thermo-responsive ionic liquids: A path to eco-friendly membrane production and multifaceted applications

We synthesized a temperature-responsive ionic liquid, [N4444][SS], and incorporated it into an environmentally friendly cellulose acetate (CA)-based battery separator. A pore was formed in the battery separator by [N4444][SS], which pierced a plasticized part due to water pressure. Varying drying temperatures during membrane fabrication revealed that the CA/[N4444][SS] membrane dried at 50 °C exhibited greater thickness and a smaller average pore size, resulting in an asymmetric internal structure. Despite the asymmetry, this membrane demonstrated significantly higher water flux and a lower Gurley value compared to the membrane dried at 25 °C, indicating minimal tortuosity and low resistance within the internal pores. Thermal behavior analysis through TGA and DSC, as well as FT-IR spectroscopy, confirmed that [N4444][SS] remains within the CA matrix, forming coordinative bonds. The findings suggest that the CA/[N4444][SS] membrane, when used as a Li-ion battery separator, could enhance Li-ion transport properties and conductivity. Moreover, the recyclability of the IL in the membrane fabrication process contributes to a more environmentally friendly approach.

An electricity-driven mobility circular economy with lifecycle carbon footprints for climate-adaptive carbon neutrality transformation

Under the carbon neutrality targets and sustainable development goals, emergingly increasing needs for batteries are in buildings and electric vehicles. However, embodied carbon emissions impose dialectical viewpoints on whether the electrochemical battery is environmentally friendly or not. In this research, a community with energy paradigm shifting towards decentralization, renewable and sustainability is studied, with multi-directional Vehicle-to-Everything (V2X) and lifecycle battery circular economy. Approaches are proposed to quantify the lifecycle carbon intensity of batteries. Afterwards, pathways for zero-carbon transformation are proposed to guide the economic feasibility of energy, social and governance investment behaviors. Results show that lifecycle zero-carbon battery can be achieved under energy paradigm shifting to positive, V2X interaction, battery cascade utilization and battery circular economy in various climate regions. This study proposes an approach for lifecycle battery carbon intensity quantification for sustainable pathways transition on zero-carbon batteries and carbon-neutral communities.

Regulation of Interfacial Chemistry Enabling High-Power Dual-Ion Batteries at Low Temperatures

Interfacial chemistry plays a crucial role in determining the electrochemical properties of low-temperature rechargeable batteries. Although existing interface engineering has significantly improved the capacity of rechargeable batteries operating at low temperatures, challenges such as sharp voltage drops and poor high-rate discharge capabilities continue to limit their applications in extreme environments. In this study, an energy-level-adaptive design strategy for electrolytes to regulate interfacial chemistry in low-temperature Li||graphite dual-ion batteries (DIBs) is proposed. This strategy enables the construction of robust interphases with superior ion-transfer kinetics. On the graphite cathode, the design endues the cathode interface with solvent/anion-coupled interfacial chemistry, which yields an nitrogen/phosphor/sulfur/fluorin (N/P/S/F)-containing organic-rich interphase to boost anion-transfer kinetics and maintains excellent interfacial stability. On the Li metal anode, the anion-derived interfacial chemistry promotes the formation of an inorganic-dominant LiF-rich interphase, which effectively suppresses Li dendrite growth and improves the Li plating/stripping kinetics at low temperatures. Consequently, the DIBs can operate within a wide temperature range, spanning from -40 to 45 °C. At -40 °C, the DIB exhibits exceptional performance, delivering 97.4% of its room-temperature capacity at 1 C and displaying an extraordinarily high-rate discharge capability with 62.3% capacity retention at 10 C. This study demonstrates a feasible strategy for the development of high-power and low-temperature rechargeable batteries.

Polymer-Supported Graphene Sheet as a Vertically Conductive Anode of Lithium-Ion Battery

The increasing demand for electric vehicles necessitates the development of cost-effective, mass-producible, long-lasting, and highly conductive batteries. Making this kind of battery is exceedingly tricky. This study introduces an innovative fabrication technique utilizing a laser-induced graphene (LIG) approach on commercial Kapton film to create hexagonal pores. These pores form vertical conduction paths for electron and ion transportation during lithiation and delithiation, significantly enhancing conductivity. The nongraphitized portion of the Kapton film makes it a binder-less, free-standing electrode, providing mechanical stability. Various analytical techniques, including scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectroscopy, and atomic force microscopy (AFM) are utilized to confirm the transformation of a 3D porous graphene sheet from a commercial Kapton film. Cross-sectional SEM images verify the vertical connections. The specific capacity of 581 mAh g-1 is maintained until the end, with 99% coulombic efficiency at 0.1C. This simple manufacturing method paves the pathway for future LIG-based, cost-effective, lightweight, mass-producible, long-lasting, vertically conductive electrodes for lithium-ion batteries.

Recycling and Reuse of Spent LIBs: Technological Advances and Future Directions

Recovering valuable metals from spent lithium-ion batteries (LIBs), a kind of solid waste with high pollution and high-value potential, is very important. In recent years, the extraction of valuable metals from the cathodes of spent LIBs and cathode regeneration technology are still rapidly developing (such as flash Joule heating technology to regenerate cathodes). This review summarized the studies published in the recent ten years to catch the rapid pace of development in this field. The development, structure, and working principle of LIBs were firstly introduced. Subsequently, the recent developments in mechanisms and processes of pyrometallurgy and hydrometallurgy for extracting valuable metals and cathode regeneration were summarized. The commonly used processes, products, and efficiencies for the recycling of nickel-cobalt-manganese cathodes (NCM/LCO/LMO/NCA) and lithium iron phosphate (LFP) cathodes were analyzed and compared. Compared with pyrometallurgy and hydrometallurgy, the regeneration method was a method with a higher resource utilization rate, which has more industrial application prospects. Finally, this paper pointed out the shortcomings of the current research and put forward some suggestions for the recovery and reuse of spent lithium-ion battery cathodes in the future.

Superspreading-Based Fabrication of Thermostable Nanoporous Polyimide Membranes for High Safety Separators of Lithium-Ion Batteries

The development of thermally stable separators is a promising approach to address the safety issues of lithium-ion batteries (LIBs) owing to the serious shrinkage of commercial polyolefin separators at elevated temperatures. However, achieving controlled nanopores with a uniform size distribution in thermostable polymeric separators and high electrochemical performance is still a great challenge. In this study, nanoporous polyimide (PI) membranes with excellent thermal stability as high-safety separators is developed for LIBs using a superspreading strategy. The superspreading of polyamic acid solutions enables the generation of thin and uniform liquid layers, facilitating the formation of thin PI membranes with controllable and uniform nanopores with narrow size distribution ranging from 121 ± 5 nm to 86 ± 6 nm. Such nanoporous PI membranes display excellent structural stability at elevated temperatures up to 300 °C for at least 1 h. LIBs assembled with nanoporous PI membranes as separators show high specific capacity and Coulombic efficiency and can work normally after transient treatment at a high temperature (150 °C for 20 min) and high ambient temperature, indicating their promising application as high-safety separators for rechargeable batteries.

Steric molecular combing effect enables Self-Healing binder for silicon anodes in Lithium-Ion batteries

Silicon is a promising anode material for lithium-ion batteries with its superior capacity. However, the volume change of the silicon anode seriously affects the electrode integrity and cycle stability. The waterborne guar gum (GG) binder has been regarded as one of the most promising binders for Si anodes. Here, a unique steric molecular combing approach based on guar gum, glycerol, and citric acid is proposed to develop a self-healing binder GGC, which would boost the structural stability of electrode materials. The GGC binder is mainly designed to weaken van der Waals' forces between polymers through the plasticizing effect of glycerol, combing and straightening the guar molecular chain of GG, and exposing the guar hydroxyl sites of GG and the carboxyl groups of citric acid. The condensation reaction between the hydroxyl sites of GG and the carboxyl groups of citric acid forms stronger hydrogen bonds, which can help achieve self-healing effect to cope with the severe volume expansion effect of silicone-based materials. Silicon electrode lithium-ion batteries prepared with GGC binders exhibit outstanding electrochemical performance, with a discharge capacity of up to 1579 mAh/g for 1200 cycles at 1 A/g, providing a high capacity retention rate of 96%. This paper demostrates the great potential of GGC binders in realizing electrochemical performance enhancement of silicon anode.

Cold-plasma activation converting conductive agent in spent Li-ion batteries to bifunctional oxygen reduction/evolution electrocatalyst for zinc-air batteries

Considerable amount of high-value transition metals components can be recycled in spent ternary lithium-ion batteries. In this study, we utilized the conductive agent carbon black, obtained from the leaching waste resulting from the chemical recovery of spent lithium-nickel-manganese-cobalt (NCM) oxide cathode materials. This process allows us to create valuable bifunctional catalysts for the oxygen reduction reaction and oxygen evolution reaction (ORR/OER), facilitated by a facile cold plasma activation method, as a part of lithium batteries circular economy. The activated conductive agent (RCA-30) exhibited an ORR half-wave potential of 0.74 V (vs. RHE) in 0.1 mol/L KOH solution, and an OER overpotential of 360 mV at 10 mA cm-2 in 1 mol/L KOH electrolyte, owing to nitrogen doping of carbon black and activation of surface metal oxides. The complete zinc-air batteries incorporating the activated catalysts at the cathode exhibited an open circuit potential of up to 1.48 V and sustained cycling for 100 h at a current density of 5 mA cm-2. Additionally, the activated catalysts contributed to a power density of 92 mW cm-2 and a full discharge capacity of 640 mAh/g.

Ferrioxalate photolysis-assisted green recovery of valuable resources from spent lithium iron phosphate batteries

Recovering valuable resources from spent cathodes while minimizing secondary waste generation is emerging as an important objective for the future recycling of spent lithium-ion batteries, including lithium iron phosphate (LFP) batteries. This study proposes the use of oxalic acid leaching followed by ferrioxalate photolysis to separate and recover cathode active material elements from spent LFP batteries. The cathode active material can be rapidly dissolved at room temperature using appropriate quantities of oxalic acid and hydrogen peroxide, as determined through thermodynamic calculations. The dissolved ferrioxalate complex ion (Fe(C2O4)33-) is selectively precipitated through subsequent photolysis at room temperature. Depending on the initial concentration, the decomposition ratio can exceed 95 % within 1-4 h. Molecular mechanism analysis reveals that the decomposition of the Fe(C2O4)33- complex ion into water-insoluble FeC2O4·2H2O results in the precipitation of iron and the separation of metal elements. Lithium can be recovered as dihydrogen phosphates through filtration and water evaporation. No additional precipitant is needed and no other side products are generated during the process. Oxalic acid leaching followed by photolysis offers an environmentally friendly and efficient method for metal recovery from spent LFP cathodes. The photochemical process is a promising approach for reducing secondary waste generation in battery recycling.

Ecotoxicological assessment, oxidative response, and enzyme activity disorder of the rotifer Brachionus asplanchnoidis exposed to a toxic cocktail of spent lithium-ion battery leachate

Spent lithium-ion batteries (LIBs) have emerged as a major source of waste due to their low recovery rate. The physical disposal of spent LIBs can lead to the leaching of their contents into the surrounding environment. While it is widely agreed that hazardous substances such as nickel and cobalt in the leachate can pose a threat to the environment and human health, the overall composition and toxicity of LIB leachate remain unclear. In this study, a chemical analysis of leachate from spent LIBs was conducted to identify its primary constituents. The ecotoxicological parameters of the model organism, rotifer Brachionus asplanchnoidis, were assessed to elucidate the toxicity of the LIB leachate. Subsequent experiments elucidated the impacts of the LIB leachate and its representative components on the malondialdehyde (MDA) level, antioxidant capacity, and enzyme activity of B. asplanchnoidis. The results indicate that both the LIB leachate and its components are harmful to individual rotifers due to the adverse effects of stress-induced disturbances in biochemical indicators, posing a threat to population development. The intensified poisoning phenomenon under combined stress suggests the presence of complex synergistic effects among the components of LIB leachate. Due to the likely environmental and biological hazards, LIBs should be strictly managed after disposal. Additionally, more economical and eco-friendly recycling and treatment technologies need to be developed and commercialized.

Data-Driven Cycle Life Prediction of Lithium Metal-Based Rechargeable Battery Based on Discharge/Charge Capacity and Relaxation Features

Achieving precise estimates of battery cycle life is a formidable challenge due to the nonlinear nature of battery degradation. This study explores an approach using machine learning (ML) methods to predict the cycle life of lithium-metal-based rechargeable batteries with high mass loading LiNi0.8Mn0.1Co0.1O2 electrode, which exhibits more complicated and electrochemical profile during battery operating conditions than typically studied LiFePO₄/graphite based rechargeable batteries. Extracting diverse features from discharge, charge, and relaxation processes, the intricacies of cell behavior without relying on specific degradation mechanisms are navigated. The best-performing ML model, after feature selection, achieves an R2 of 0.89, showcasing the application of ML in accurately forecasting cycle life. Feature importance analysis unveils the logarithm of the minimum value of discharge capacity difference between 100 and 10 cycle (Log(|min(ΔDQ 100-10(V))|)) as the most important feature. Despite the inherent challenges, this model demonstrates a remarkable 6.6% test error on unseen data, underscoring its robustness and potential for transformative advancements in battery management systems. This study contributes to the successful application of ML in the realm of cycle life prediction for lithium-metal-based rechargeable batteries with practically high energy density design.

Noncovalent Interactions-Driven Self-Assembly of Polyanionic Additive for Long Anti-Calendar Aging and High-Rate Zinc Metal Batteries

Zinc anodes of zinc metal batteries suffer from unsatisfactory plating/striping reversibility due to interfacial parasitic reactions and poor Zn2+ mass transfer kinetics. Herein, methoxy polyethylene glycol-phosphate (mPEG-P) is introduced as an electrolyte additive to achieve long anti-calendar aging and high-rate capabilities. The polyanionic of mPEG-P self-assembles via noncovalent-interactions on electrode surface to form polyether-based cation channels and in situ organic-inorganic hybrid solid electrolyte interface layer, which ensure rapid Zn2+ mass transfer and suppresses interfacial parasitic reactions, realizing outstanding cycling/calendar aging stability. As a result, the Zn//Zn symmetric cells with mPEG-P present long lifespans over 9000 and 2500 cycles at ultrahigh current densities of 120 and 200 mA cm-2, respectively. Besides, the coulombic efficiency (CE) of the Zn//Cu cell with mPEG-P additive (88.21%) is much higher than that of the cell (36.4%) at the initial cycle after the 15-day calendar aging treatment, presenting excellent anti-static corrosion performance. Furthermore, after 20-day aging, the Zn//MnO2 cell exhibits a superior capacity retention of 89% compared with that of the cell without mPEG-P (28%) after 150 cycles. This study provides a promising avenue for boosting the development of high efficiency and durable metallic zinc based stationary energy storage system.

Reviving Fatigue Surface for Solid-State Upcycling of Highly Degraded Polycrystalline LiNi1-x-yCoxMnyO2 Cathodes

The ongoing tide of spent lithium-ion batteries (LIBs) urgently calls for high-value output in efficient recycling. Recently, direct regeneration has emerged as a novel recycling strategy but fails to repair the irreversible morphology and structure damage of the highly degraded polycrystalline layered oxide materials. Here, this work carries out a solid-state upcycling study for the severely cracked LiNi1-x-yCoxMnyO2 cathodes. The specific single-crystallization process during calcination is investigated and the surface rock salt phase is recognized as the intrinsic obstacle to the crystal growth of the degraded cathodes due to sluggish diffusion in the heterogeneous grain boundary. Accordingly, this work revives the fatigue rock salt phase by restoring a layered surface and successfully reshapes severely broken cathodes into the high-performance single-crystalline particles. Benefiting from morphological and structural integrity, the upcycled single-crystalline cathode materials exhibit an enhanced capacity retention rate of 93.5% after 150 cycles at 1C compared with 61.7% of the regenerated polycrystalline materials. The performance is also beyond that of the commercial cathodes even under a high cut-off voltage (4.5 V) or high operating temperature (45 °C). This work provides scientific insights for the upcycling of the highly degraded cathodes in spent LIBs.

Boron-doped three-dimensional porous carbon framework/carbon shell encapsulated silicon composites for high-performance lithium-ion battery anodes

Deleterious volumetric expansion and poor electrical conductivity seriously hinder the application of Si-based anode materials in lithium-ion batteries (LIBs). Herein, boron-doped three-dimensional (3D) porous carbon framework/carbon shell encapsulated silicon (B-3DCF/Si@C) hybrid composites are successfully prepared by two coating and thermal treatment processes. The presence of 3D porous carbon skeleton and carbon shell effectively improves the mechanical properties of the B-3DCF/Si@C electrode during the cycling process, ensures the stability of the electrical contacts of the silicon particles and stabilizes the solid electrolyte interface (SEI) layer, thus enhancing the electronic conductivity and ion migration efficiency of the anode. The developed B-3DCF/Si@C anode has a high reversible capacity, excellent cycling stability and outstanding rate performance. A reversible capacity of 1288.5 mAh/g is maintained after 600 cycles at a current density of 400 mA g-1. The improved electrochemical performance is demonstrated in a full cell using a LiFePO4-based cathode. This study presents a novel approach that not only mitigates the large volume expansion effects in LIB anode materials, but also provides a reference model for the preparation of porous composites with various functionalities.

Fast-Charging Phosphorus-Based Anodes: Promises, Challenges, and Pathways for Improvement

Fast-charging batteries are highly sought after. However, the current battery industry has used carbon as the preferred anode, which can suffer from dendrite formation problems at high current density, causing failure after prolonged cycling and posing safety hazards. The phosphorus (P) anode is being considered as a promising successor to graphite due to its safe lithiation potential, low ion diffusion energy barrier, and high theoretical storage capacity. Since 2019, fast-charging P-based anodes have realized the goals of extreme fast charging (XFC), which enables a 10 min recharging time to deliver a capacity retention larger than 80%. Rechargeable battery technologies that use P-based anodes, along with high-capacity conversion-type cathodes or high-voltage insertion-type cathodes, have thus garnered substantial attention from both the academic and industry communities. In spite of this activity, there remains a rather sparse range of high-performance and fast-charging P-based cell configurations. Herein, we first systematically examine four challenges for fast-charging P-based anodes, including the volumetric variation during the cycling process, the electrode interfacial instability, the dissolution of polyphosphides, and the long-lasting P/electrolyte side reactions. Next, we summarize a range of strategies with the potential to circumvent these challenges and rationally control electrochemical reaction processes at the P anode. We also consider both binders and electrode structures. We also propose other remaining issues and corresponding strategies for the improvement and understanding of the fast-charging P anode. Finally, we review and discuss the existing full cell configurations based on P anodes and forecast the potential feasibility of recycling spent P-based full cells according to the trajectory of recent developments in batteries. We hope this review affords a fresh perspective on P science and engineering toward fast-charging energy storage devices.

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.

Recycling of spent lithium-ion batteries for a sustainable future: recent advancements

Lithium-ion batteries (LIBs) are widely used as power storage systems in electronic devices and electric vehicles (EVs). Recycling of spent LIBs is of utmost importance from various perspectives including recovery of valuable metals (mostly Co and Li) and mitigation of environmental pollution. Recycling methods such as direct recycling, pyrometallurgy, hydrometallurgy, bio-hydrometallurgy (bioleaching) and electrometallurgy are generally used to resynthesise LIBs. These methods have their own benefits and drawbacks. This manuscript provides a critical review of recent advances in the recycling of spent LIBs, including the development of recycling processes, identification of the products obtained from recycling, and the effects of recycling methods on environmental burdens. Insights into chemical reactions, thermodynamics, kinetics, and the influence of operating parameters of each recycling technology are provided. The sustainability of recycling technologies (e.g., life cycle assessment and life cycle cost analysis) is critically evaluated. Finally, the existing challenges and future prospects are presented for further development of sustainable, highly efficient, and environmentally benign recycling of spent LIBs to contribute to the circular economy.

Designer Lithium Reservoirs for Ultralong Life Lithium Batteries for Grid Storage

The minimization of irreversible active lithium loss stands as a pivotal concern in rechargeable lithium batteries, particularly in the context of grid-storage applications, where achieving the utmost energy density over prolonged cycling is imperative to meet stringent demands, notably in terms of life cost. Departing from conventional methodologies advocating electrode prelithiation and/or electrolyte additives, a new paradigm is proposed here: the integration of a designer lithium reservoir (DLR) featuring lithium orthosilicate (Li4SiO4) and elemental sulfur. This approach concurrently addresses active lithium consumption through solid electrolyte interphase (SEI) formation and mitigates minor yet continuous parasitic reactions at the electrode/electrolyte interface during extended cycling. The remarkable synergy between the Li-ion conductive Li4SiO4 and the SEI-favorable elemental sulfur enables customizable compensation kinetics for active lithium loss throughout continuous cycling. The introduction of a minute quantity of DLR (3 wt% Li4SiO4@S) yields outstanding cycling stability in a prototype pouch cell (graphite||LiFePO4) with an ampere-hour-level capacity (≈2.3 Ah), demonstrating remarkable capacity retention (≈95%) even after 3000 cycles. This utilization of a DLR is poised to expedite the development of enduring lithium batteries for grid-storage applications and stimulate the design of practical, implantable rechargeable batteries based on related cell chemistries.

Stabilizing Solid Electrolyte Interphase on Liquid Metal Via Dynamic Hydrogel-Derived Carbon Framework Encapsulation

Eutectic gallium-indium liquid metal (EGaIn-LM), with a considerable capacity and unique self-healing properties derived from its intrinsic liquid nature, gains tremendous attention for lithium-ion batteries (LIBs) anode. However, the fluidity of the LM can trigger continuous consumption of the electrolyte, and its liquid-solid transition during the lithiation/de-lithiation process may result in the rupture of the solid electrolyte interface (SEI). Herein, LM is employed as an initiator to in situ assemble the 3D hydrogel for dynamically encapsulating itself; the LM nanoparticles can be homogeneously confined within the hydrogel-derived carbon framework (HDC) after calcination. Such design effectively alleviates the volume expansion of LM and facilitates electron transportation, resulting in a superior rate capability and long-term cyclability. Further, the "dual-layer" SEI structure and its key components, including the robust LiF outer layer and corrosion-resistant and ionic conductive LiGaOx inner layer are revealed, confirming the involvement of LM in the formation of SEI, as well as the important role of carbon framework in reducing interfacial side reactions and SEI decomposition. This work provides a distinct perspective for the formation, structural evolution, and composition of SEI at the liquid/solid interface, and demonstrates an effective strategy to construct a reliable matrix for stabilizing the SEI.

A raising alarm on the current global electronic waste situation through bibliometric analysis, life cycle, and techno-economic assessment: a review

Electronic waste (E-waste) production worldwide is increasing three times faster than the growth of the global population, and it is predicted that the total volume of E-waste will reach 74 million tonnes by 2030. United Nations warned that unless emissions of heat-trapping gases are drastically reduced, humanity will face catastrophic climate change. We created a bibliometric analysis and discussed the life cycle and techno-economic assessments of the current E-waste situation. We found trending E-waste topics, particularly those related to industrial facilities implementing a circular economy framework and improving the recycling methods of lithium-ion batteries, and this was linked to the topic of electric vehicles. Other research themes included bioleaching, hydrometallurgy, reverse logistics, heavy metal life cycle assessment, and sustainability. These topics can interest industrial factories and scientists interested in these fields. Also, throughout techno-economic assessments, we highlighted several economic and investment opportunities to benefit stakeholders from E-waste recycling. While the rate of E-waste is increasing, consumer education on the proper E-waste management strategies, a collaboration between international organizations with the industrial sector, and legislation of robust E-waste regulations may reduce the harmful effect on humans and the environment and increase the income to flourish national economies.

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.

Kinetic Evaluation on Lithium Polysulfide in Weakly Solvating Electrolyte toward Practical Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are highly considered as next-generation energy storage techniques. Weakly solvating electrolyte with low lithium polysulfide (LiPS) solvating power promises Li anode protection and improved cycling stability. However, the cathodic LiPS kinetics is inevitably deteriorated, resulting in severe cathodic polarization and limited energy density. Herein, the LiPS kinetic degradation mechanism in weakly solvating electrolytes is disclosed to construct high-energy-density Li-S batteries. Activation polarization instead of concentration or ohmic polarization is identified as the dominant kinetic limitation, which originates from higher charge-transfer activation energy and a changed rate-determining step. To solve the kinetic issue, a titanium nitride (TiN) electrocatalyst is introduced and corresponding Li-S batteries exhibit reduced polarization, prolonged cycling lifespan, and high actual energy density of 381 Wh kg-1 in 2.5 Ah-level pouch cells. This work clarifies the LiPS reaction mechanism in protective weakly solvating electrolytes and highlights the electrocatalytic regulation strategy toward high-energy-density and long-cycling Li-S batteries.

Physics-informed neural network for lithium-ion battery degradation stable modeling and prognosis

Accurate state-of-health (SOH) estimation is critical for reliable and safe operation of lithium-ion batteries. However, reliable and stable battery SOH estimation remains challenging due to diverse battery types and operating conditions. In this paper, we propose a physics-informed neural network (PINN) for accurate and stable estimation of battery SOH. Specifically, we model the attributes that affect the battery degradation from the perspective of empirical degradation and state space equations, and utilize neural networks to capture battery degradation dynamics. A general feature extraction method is designed to extract statistical features from a short period of data before the battery is fully charged, enabling our method applicable to different battery types and charge/discharge protocols. Additionally, we generate a comprehensive dataset consisting of 55 lithium-nickel-cobalt-manganese-oxide (NCM) batteries. Combined with three other datasets from different manufacturers, we use a total of 387 batteries with 310,705 samples to validate our method. The mean absolute percentage error (MAPE) is 0.87%. Our proposed PINN has demonstrated remarkable performance in regular experiments, small sample experiments, and transfer experiments when compared to alternative neural networks. This study highlights the promise of physics-informed machine learning for battery degradation modeling and SOH estimation.

A simplified electrochemical model for lithium-ion batteries based on ensemble learning

The mass transfer in lithium-ion batteries is a low-frequency dynamic that affects their voltage and performance. To find an effective way to describe the mass transfer in lithium-ion batteries, a simplified electrochemical lithium-ion battery model based on ensemble learning is proposed. The proposed model simplifies lithium-ion transfer in electrode particles with ensemble learning which ensembles discrete-time realization algorithm (DRA), fractional-order Padé approximation model (FOM), and three parameters (TPM) parabolic. The lithium-ion transfer in the electrolyte is simplified by the first-order inertial element (FIE). The results show that the proposed model achieves not only accurate lithium-ion concentration prediction in solid and electrolyte phase but also precise voltage prediction with low computational complexity.

Sustainable upcycling of mixed spent cathodes to a high-voltage polyanionic cathode material

Sustainable battery recycling is essential for achieving resource conservation and alleviating environmental issues. Many open/closed-loop strategies for critical metal recycling or direct recovery aim at a single component, and the reuse of mixed cathode materials is a significant challenge. To address this barrier, here we propose an upcycling strategy for spent LiFePO4 and Mn-rich cathodes by structural design and transition metal replacement, for which uses a green deep eutectic solvent to regenerate a high-voltage polyanionic cathode material. This process ensures the complete recycling of all the elements in mixed cathodes and the deep eutectic solvent can be reused. The regenerated LiFe0.5Mn0.5PO4 has an increased mean voltage (3.68 V versus Li/Li+) and energy density (559 Wh kg-1) compared with a commercial LiFePO4 (3.38 V and 524 Wh kg-1). The proposed upcycling strategy can expand at a gram-grade scale and was also applicable for LiFe0.5Mn0.5PO4 recovery, thus achieving a closed-loop recycling between the mixed spent cathodes and the next generation cathode materials. Techno-economic analysis shows that this strategy has potentially high environmental and economic benefits, while providing a sustainable approach for the value-added utilization of waste battery materials.

Recyclable Organic Radical Electrodes for Metal-Free Batteries

Organic batteries are one of the possible routes for transitioning to sustainable energy storage solutions. However, the recycling of organic batteries, which is a key step toward circularity, is not easily achieved. This work shows the direct recycling of poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl) (PTMA) and poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl acrylamide) (PTAm) based composite electrodes. After charge-discharge cycling, the electrodes are deconstructed using a solubilizing-solvent and then reconstructed using a casting-solvent. The electrochemical properties of the original and recycled electrodes are compared using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) cycling, from which it is discovered using time-of-flight secondary ion mass spectrometry (ToF-SIMS) that recycling can be challenged by the formation of a cathode electrolyte interphase (CEI). In turn, an additive is proposed to modify the CEI layer and improve the properties after recycling. Last, an anionic rocking chair battery consisting of PTAm electrodes as both positive and negative electrodes is demonstrated, in which the electrodes are recycled to form a new battery. This work demonstrates the recycling of composite electrodes for organic batteries and provides insights into the challenges and possible solutions for recycling the next-generation electrochemical energy storage devices.

Contact-electro-catalysis (CEC)

Contact-electro-catalysis (CEC) is an emerging field that utilizes electron transfer occurring at the liquid-solid and even liquid-liquid interfaces because of the contact-electrification effect to stimulate redox reactions. The energy source of CEC is external mechanical stimuli, and solids to be used are generally organic as well as in-organic materials even though they are chemically inert. CEC has rapidly garnered extensive attention and demonstrated its potential for both mechanistic research and practical applications of mechanocatalysis. This review aims to elucidate the fundamental principle, prominent features, and applications of CEC by compiling and analyzing the recent developments. In detail, the theoretical foundation for CEC, the methods for improving CEC, and the unique advantages of CEC have been discussed. Furthermore, we outline a roadmap for future research and development of CEC. We hope that this review will stimulate extensive studies in the chemistry community for investigating the CEC, a catalytic process in nature.

In Situ Constructed Spinel Layer Stabilized Upcycled LiCoO2 for High Performance Lithium-Ion Batteries

With ever-increasing requirements for cathodes in the lithium-ion batteries market, an efficiency and eco-friendly upcycling regeneration strategy is imperative to meet the demand for high-performance cathode materials. Herein, a facile, direct and upcycling regeneration strategy is proposed to restore the failed LiCoO2 and enhance the stability at 4.6 V. Double effects combination of relithiation and outside surface reconstruction are simultaneously achieved via a facile solid-phase sintering method. The evolution process of the Li-supplement and grain-recrystallization is systematically investigated, and the high performance of the upcycled materials at high voltage is comprehensively demonstrated. Thanks to the favorable spinel LiCoxMn2-xO4 surface coating, the upcycled sample displays outstanding electrochemical performance, superior to the pristine cathode materials. Notably, the 1% surface-coated LiCoO2 achieves a high discharge-specific capacity of 207.9 mA h g-1 at 0.1 C and delivers excellent cyclability with 77.0% capacity retention after 300 cycles. Significantly, this in situ created spinel coating layer can be potentially utilized for recycling spent LiCoO2, thus providing a viable, promising recycling strategy insights into the upcycling of degraded cathodes.

Green Synergy Conversion of Waste Graphite in Spent Lithium-Ion Batteries to GO and High-Performance EG Anode Material

The increasing demand for graphite and the higher lithium content than environment abundance make the recycling of anode in spent lithium-ion batteries (LIBs) also become an inevitable trend. This work proposes a simple pathway to convert the retired graphite to high-performance expanded graphite (EG) under mild conditions. After the oxidation and intercalation by FeCl3 for the retired graphite, H2O2 molecules are more likely to penetrate into the extended layers. And the gas phase diffusion caused by the produced O2 from the redox reaction between FeCl3 and H2O2 further promotes lattice expansion of interlayers (0.535 nm), which is beneficial to the stripping of graphene oxide (GO) with fewer layers. The EG exhibits excellent electrochemical performances in both LIBs and sodium-ion batteries (SIBs). It delivers 331.5 mAh g-1 at 3C (1C = 372 mA g-1) in LIBs, while it achieves 176.8 mAh g-1 at 3C (1C = 120 mA g-1) in SIBs. Then the capacity retains 753.6 (LIBs) and 201.6 (SIBs) mAh g-1 after a long-term cycling of 500 times at 1C, respectively. The full cells with the EG electrodes after prelithium/presodiation also show excellent cycle stability. Thus, this work offers another referable strategy for the recycling of waste graphite in spent LIBs.

Health diagnosis and recuperation of aged Li-ion batteries with data analytics and equivalent circuit modeling

Battery health assessment and recuperation play crucial roles in the utilization of second-life Li-ion batteries. However, due to ambiguous aging mechanisms, it is challenging to estimate battery health and devise an effective strategy for cell rejuvenation. This paper presents aging and reconditioning experiments of 62 commercial lithium iron phosphate cells, which allow us to use machine learning models to predict cycle life and identify important indicators of recoverable capacity. An average test error of 16.84% ± 1.87% (mean absolute percentage error) for cycle life prediction is achieved by gradient boosting regressor. Some of the recoverable lost capacity is found to be attributed to the non-uniformity in electrodes. An experimentally validated equivalent circuit model is built to demonstrate how such non-uniformity can be accumulated, and how it can give rise to recoverable capacity loss. Furthermore, Shapley additive explanations (SHAP) analysis also reveals that battery operation history significantly affects the capacity recovery.

Controllable synthesis of crystalline germanium nanorods as anode for lithium-ion batteries with high cycling stability

Germanium (Ge) nanomaterials have emerged as promising anode materials for lithium-ion batteries (LIBs) due to their higher capacity compared to commercial graphite. However, their practical application has been limited by the high cost associated with harsh preparation conditions and the poor electrode cycling stability in charging and diacharging. In this study, we successfully synthesized crystalline Ge nanorods through the reaction of intermetallic compound CaGe and ZnCl2. Ge nanorods with different morphologies and crystallinity can be obtained through precisely controlling the reaction temperature. When employed as electrodes for LIBs, the Ge nanorods demonstrate exceptional long-term cyclic stability. Even after 1000 cycles at a high rate of 2C (1C = 1600 mA g-1), it exhibits a remarkable reversible capacity of around 1000 mAh/g. Furthermore, such Ge electrode displays excellent cycling performance across a wide temperature range. And it could achieve reversible capacities of 1267, 832, and 690 mAh/g, with the rate of 1C, at temperatures of 20, 0, and -20 °C, respectively. Above all, our study offers a cost-effective approach for the synthesis of crystalline Ge nanorods, addressing the concerns associated with high production costs. And the application of Ge nanorods as anode materials in LIBs over a wide temperature range opens up new possibilities for the development of advanced energy storage systems.

Si Nanowires: From Model System to Practical Li-Ion Anode Material and Beyond

Nanowire (NW)-based anodes for Li-ion batteries (LIBs) have been under investigation for more than a decade, with their unique one-dimensional (1D) morphologies and ability to transform into interconnected active material networks offering potential for enhanced cycling stability with high capacity. This is particularly true for silicon (Si)-based anodes, where issues related to large volumetric expansion can be partially mitigated and the cycle life can be enhanced. In this Perspective, we highlight the trajectory of Si NWs from a model system to practical Li-ion battery anode material and future prospects for extension to beyond Li-ion batteries. The study examines key research areas related to Si NW-based anodes, including state-of-the-art (SoA) characterization approaches followed by practical anode design considerations, including NW composite anode formation and upscaling/full-cell considerations. An outlook on the practical prospects of NW-based anodes and some future directions for study are detailed.

A Gradient Composite Structure Enables a Stable Microsized Silicon Suboxide-Based Anode for a High-Performance Lithium-Ion Battery

The practical application of microsized anodes is hindered by severe volume changes and fast capacity fading. Herein, we propose a gradient composite strategy and fabricate a silicon suboxide-based composite anode (d-SiO@SiOx/C@C) consisting of a disproportionated microsized SiO inner core, a homogeneous composite SiOx/C interlayer (x ≈ 1.5), and a highly graphitized carbon outer layer. The robust SiOx/C interlayer can realize a gradient abatement of stress and simultaneously connect the inner SiO core and carbon outer layer through covalent bonds. As a result, d-SiO@SiOx/C@C delivers a specific capacity of 1023 mAh/g after 300 cycles at 1 A/g with a retention of >90% and an average Coulombic efficiency of >99.7%. A full cell assembled with a LiNi0.8Co0.15Al0.05O2 cathode displays a remarkable specific energy density of 569 Wh/kg based on total active materials as well as excellent cycling stability. Our strategy provides a promising alternative for designing structurally and electrochemically stable microsized anodes with high capacity.

Lithium-ion battery second life: pathways, challenges and outlook

Net zero targets have resulted in a drive to decarbonise the transport sector worldwide through electrification. This has, in turn, led to an exponentially growing battery market and, conversely, increasing attention on how we can reduce the environmental impact of batteries and promote a more efficient circular economy to achieve real net zero. As these batteries reach the end of their first life, challenges arise as to how to collect and process them, in order to maximise their economical use before finally being recycled. Despite the growing body of work around this topic, the decision-making process on which pathways batteries could take is not yet well understood, and clear policies and standards to support implementation of processes and infrastructure are still lacking. Requirements and challenges behind recycling and second life applications are complex and continue being defined in industry and academia. Both pathways rely on cell collection, selection and processing, and are confronted with the complexities of pack disassembly, as well as a diversity of cell chemistries, state-of-health, size, and form factor. There are several opportunities to address these barriers, such as standardisation of battery design and reviewing the criteria for a battery's end-of-life. These revisions could potentially improve the overall sustainability of batteries, but may require policies to drive such transformation across the industry. The influence of policies in triggering a pattern of behaviour that favours one pathway over another are examined and suggestions are made for policy amendments that could support a second life pipeline, while encouraging the development of an efficient recycling industry. This review explains the different pathways that end-of-life EV batteries could follow, either immediate recycling or service in one of a variety of second life applications, before eventual recycling. The challenges and barriers to each pathway are discussed, taking into account their relative environmental and economic feasibility and competing advantages and disadvantages of each. The review identifies key areas where processes need to be simplified and decision criteria clearly defined, so that optimal pathways can be rapidly determined for each end-of-life battery.

Solvothermal Guided V2O5 Microspherical Nanoparticles Constructing High-Performance Aqueous Zinc-Ion Batteries

Rechargeable aqueous zinc-ion batteries have attracted a lot of attention owing to their cost effectiveness and plentiful resources, but less research has been conducted on the aspect of high volumetric energy density, which is crucial to the space available for the batteries in practical applications. In this work, highly crystalline V2O5 microspheres were self-assembled from one-dimensional V2O5 nanorod structures by a template-free solvothermal method, which were used as cathode materials for zinc-ion batteries with high performance, enabling fast ion transport, outstanding cycle stability and excellent rate capability, as well as a significant increase in tap density. Specifically, the V2O5 microspheres achieve a reversible specific capacity of 414.7 mAh g-1 at 0.1 A g-1, and show a long-term cycling stability retaining 76.5% after 3000 cycles at 2 A g-1. This work provides an efficient route for the synthesis of three-dimensional materials with stable structures, excellent electrochemical performance and high tap density.

Superstructure-Assisted Single-Atom Catalysis on Tungsten Carbides for Bifunctional Oxygen Reactions

Single-atom catalysis (SAC) attracts wide interest for zinc-air batteries that require high-performance bifunctional electrocatalysts for oxygen reactions. However, catalyst design is still highly challenging because of the insufficient driving force for promoting multiple-electron transfer kinetics. Herein, we report a superstructure-assisted SAC on tungsten carbides for oxygen evolution and reduction reactions. In addition to the usual single atomic sites, strikingly, we reveal the presence of highly ordered Co superstructures in the interfacial region with tungsten carbides that induce internal strain and promote bifunctional catalysis. Theoretical calculations show that the combined effects from superstructures and single atoms strongly reduce the adsorption energy of intermediates and overpotential of both oxygen reactions. The catalyst therefore presented impressive bifunctional activity with an ultralow potential gap of 0.623 V and delivered a high power density of 188.5 mW cm-2 for assembled zinc-air batteries. This work opens up new opportunities for atomic catalysis.

Recycling the Spent LiNi1- x - yMnxCoyO2 Cathodes for High-Performance Electrocatalysts toward Both the Oxygen Catalytic and Methanol Oxidation Reactions

The traditional recycling methods of the spent lithium ion batteries (LIBs) involve the intricate and cumbersome steps. This work proposes a facile method of acid leaching followed by the sulfurization treatment to achieve the high Li leaching efficiency, and obtain high-performance multi-function electrocatalysts for oxygen reduction (ORR), oxygen evolution (OER), and methanol oxidation reactions (MOR) from the spent LIB ternary cathodes. By this method, the Li leaching efficiency from the spent LIB ternary cathode can reach 98.3%, and the transition metal sulfide heterostructures (LNMCO-H-450S) consisting MnS, NiS2, and NiCo2S4 phases can be obtained. LNMCO-H-450S shows the superior bifunctional oxygen catalytic activities with ORR half-wave potential of 0.763 V and OER potential at 10 mA cm-2 of 1.561 V, surpassing most of the state-of-the-art electrocatalysts. LNMCO-H-450S also demonstrates the superior MOR catalytic activity with the potential at 100 mA cm-2 being 1.37 V. Using LNMCO-H-450S as the oxygen catalyst, this work can construct the aqueous and solid-state zinc-air batteries with high power density of 309 and 257 mW cm-2, respectively. This work provides a promising strategy for the efficient recovery of Li, and reutilization of Ni, Co, and Mn from the spent LIB ternary cathodes.

Boosting the Cycle Performance of Iron Trifluoride Based Solid State Batteries at Elevated Temperatures by Engineering the Cathode Solid Electrolyte Interface

Iron trifluoride (FeF3) is attracting tremendous interest due to its lower cost and the possibility to enable higher energy density in lithium-ion batteries. However, its cycle performance deteriorates rapidly in less than 50 cycles at elevated temperatures due to cracking of the unstable cathode solid electrolyte interface (CEI) followed by active materials dissolution in liquid electrolyte. Herein, by engineering the salt composition, the Fe3O4-type CEI with the doping of boron (B) atoms in a polymer electrolyte at 60 °C is successfully stabilized. The cycle life of the well-designed FeF3-based composite cathode exceeds an unprecedented 1000 cycles and utilizes up to 70% of its theoretical capacities. Advanced electron microscopy combined with density functional theory (DFT) calculations reveal that the B in lithium salt migrates into the cathode and promotes the formation of an elastic and mechanic robust boron-contained CEI (BOR-CEI) during cycling, by which the durability of the CEI to frequent cyclic large volume changes is significantly enhanced. To this end, the notorious active materials dissolution is largely prohibited, resulting in a superior cycle life. The results suggest that engineering the CEI such as tuning its composition is a viable approach to achieving FeF3 cathode-based batteries with enhanced performance.

Activating the MnS0.5Se0.5 Microspheres as High-Performance Cathode Materials for Aqueous Zinc-Ion Batteries: Insight into In Situ Electrooxidation Behavior and Energy Storage Mechanisms

Manganese-based materials are regarded as the most prospective cathode materials because of their high natural abundance, low toxicity, and high specific capacity. Nevertheless, the low conductivity, poor cycling performance, and controversial energy storage mechanisms hinder their practical application. Here, the MnS0.5Se0.5 microspheres are synthesized by a two-step hydrothermal approach and employed as cathode materials for aqueous zinc-ion batteries (AZIBs) for the first time. Interestingly, in-depth ex situ tests and electrochemical kinetic analyses reveal that MnS0.5Se0.5 is first irreversibly converted into low-crystallinity ZnMnO3 and MnOx by in situ electrooxidation (MnS0.5Se0.5-EOP) during the first charging process, and then a reversible co-insertion/extraction of H+/Zn2+ occurs in the as-obtained MnS0.5Se0.5-EOP electrode during the subsequent discharging and charging processes. Benefiting from the increased surface area, shortened ion transport path, and stable lamellar microsphere structure, the MnS0.5Se0.5-EOP electrodes deliver high reversible capacity (272.8 mAh g-1 at 0.1 A g-1), excellent rate capability (91.8 mAh g-1 at 2 A g-1), and satisfactory cyclic stability (82.1% capacity retention after 500 cycles at 1 A g-1). This study not only provides a powerful impetus for developing new types of manganese-based chalcogenides, but also puts forward a novel perspective for exploring the intrinsic mechanisms of in situ electrooxidation behavior.

Ultraviolet Light Debondable Optically Clear Adhesives for Flexible Displays through Efficient Visible-Light Curing

With growing sustainability concerns, the need for products that facilitate easy disassembly and reuse has increased. Adhesives, initially designed for bonding, now face demands for selective removal, enabling rapid assembly-disassembly and efficient maintenance across industries. This need is particularly evident in the display industry, with the rise of foldable devices necessitating specialized adhesives. A novel optically clear adhesive (OCA) is presented for foldable display, featuring a unique UV-stimulated selective removal feature. This approach incorporates benzophenone derivatives into the polymer network, facilitating rapid debonding under UV irradiation. A key feature of this method is the adept use of visible-light-driven radical polymerization for OCA film fabrication. This method shows remarkable compatibility with various monomers and exhibits orthogonal reactivity to benzophenone, rendering it ideal for large-scale production. The resultant OCA not only has high transparency and balanced elasticity, along with excellent resistance to repeated folding, but it also exhibits significantly reduced adhesion when exposed to UV irradiation. By merging this customized formulation with strategically integrated UV-responsive elements, an effective solution is offered that enhances manufacturing efficiency and product reliability in the rapidly evolving field of sustainable electronics and displays. This research additionally contributes to eco-friendly device fabrication, aligning with emerging technology demands.

Grave-to-cradle photothermal upcycling of waste polyesters over spent LiCoO2

Lithium-ion batteries (LIBs) and plastics are pivotal components of modern society; nevertheless, their escalating production poses formidable challenges to resource sustainability and ecosystem integrity. Here, we showcase the transformation of spent lithium cobalt oxide (LCO) cathodes into photothermal catalysts capable of catalyzing the upcycling of diverse waste polyesters into high-value monomers. The distinctive Li deficiency in spent LCO induces a contraction in the Co-O6 unit cell, boosting the monomer yield exceeding that of pristine LCO by a factor of 10.24. A comprehensive life-cycle assessment underscores the economic viability of utilizing spent LCO as a photothermal catalyst, yielding returns of 129.6 $·kgLCO-1, surpassing traditional battery recycling returns (13-17 $·kgLCO-1). Solar-driven recycling 100,000 tons of PET can reduce 3.459 × 1011 kJ of electric energy and decrease 38,716 tons of greenhouse gas emissions. This work unveils a sustainable solution for the management of spent LIBs and plastics.

Selective Recovery of Battery-Grade Li2CO3 from Spent NCM Cathode Materials Using a One-Step Method of CO2 Carbonation Recovery Without Acids or Bases

The recovery of spent lithium-ion batteries by traditional acid leaching is limited by serious pollution, complicated technology, and the low purity of Li2CO3. To address the problems of the traditional acid leaching process and increasing demand for decarbonization, a technique for the selective carbonation leaching of Li and the recovery of battery-grade Li2CO3 by a simple concentration precipitation process without acids or bases was developed. The coupling of CO2 and reducing agents could effectively promote the precipitation of MCO3 (M=Ni/Co/Mn) and the selective leaching of Li by decreasing the reducing capability needed for transition metals and decreasing the pH of the solution. The optimal selective leaching process of Li was obtained under 1 MPa CO2 with 20 g/L Na2S2O3 at an L/S ratio of 30 mL/g for 1.5 h. FT-IR, XRD, ICP-MS and other methods were used to reveal the multiphase interfacial reaction mechanism of the carbonation reduction of layered cathode materials, which indicated that the reducing agent Na2S2O3 could promote lattice distortion of the cathode materials and effective separation of Li. In summary, a green and economical method for the selective recovery of battery-grade Li2CO3 using a one-step method of CO2 carbonation recovery in a near-neutral environment was proposed.

Recycling of metals from LiFePO4 battery cathode material by using ionic liquid based-aqueous biphasic systems

Lithium-ion batteries are essential for electric vehicles and energy storage devices. With the increasing demand for their production and the concomitant surge in waste generation, the need for an efficient and environmentally friendly recycling process has become imperative. This work presents a new approach for recycling of metals from the LiFePO4 (LFP) cathode material. The cathode material was first leached by a HCl solution without an oxidizing agent. Subsequently, an ionic-liquid-based aqueous biphasic system (IL-based ABS) was used for the separation of lithium and iron from leachate solutions, followed by a precipitation process. The influence of the acid concentration, solid-to-liquid ratio and leaching time on the leaching yield was investigated. UV-vis absorption spectra revealed the presence of mixed-valent iron in the leachate, with 83 ± 1% Fe(ii) and 17 ± 1% Fe(iii). The ABS systems comprised tributyltetradecylphosphonium chloride [P44414]Cl and a salting-out agent (HCl or NaCl). The extraction percentage of iron reached 90% and less than 1% of lithium was extracted under the studied optimal conditions. Further enhancement of iron extraction, reaching 98%, was achieved via a two-stage cross-current extraction process. Iron was precipitated from the loaded IL phase with an efficiency of 97% as Fe(OH)2 and Fe(OH)3, using an aqueous ammonia solution. Lithium was precipitated as Li3PO4 with a lithium purity of 99.5% by adding K3PO4 solution. The ionic liquid used in the process was efficiently regenerated and used in four extraction cycles with no activity decline, with an extraction percentage of 90% of iron in each cycle.

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.

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.

Resource recovery and regeneration strategies for spent lithium-ion batteries: Toward sustainable high-value cathode materials

Traditional cathode recycling methods have become outdated amid growing concerns for high-value output and environmental friendliness in spent Li-ion battery (LIB) recycling. Our study presents a closed-loop approach that involves selective sulfurization roasting, water leaching, and regeneration, efficiently transforming spent ternary Li batteries (i.e., NCM) into high-performance cathode materials. By combining experimental investigations with density functional theory (DFT) calculations, we elucidate the mechanisms within the NCM-C-S roasting system, providing a theoretical foundation for selective sulfidation. Utilizing in situ X-ray diffraction techniques and a series of consecutive experiments, the study meticulously tracks the evolution of regenerating cathode materials that use transition metal sulfides as their primary raw materials. The Li-rich regenerated NCM exhibits exceptional electrochemical performance, including long-term cycling, high-rate capabilities, reversibility, and stability. The closed-loop approach highlights the sustainability and environmental friendliness of this recycling process, with potential applications in other cathode materials, such as LiCoO2 and LiMn2O4. Compared with traditional methods, this short process approach avoids the complexity of leaching, solvent extraction, and reverse extraction, significantly increasing metal utilization and Li recovery rates while reducing pollution and resource waste.

Dynamic hydrogen bond cross-linking binder with self-healing chemistry enables high-performance silicon anode in lithium-ion batteries

The structure instability and cycling decay of silicon (Si) anode triggered by stress buildup hinder its practical application to next-generation high-energy-density lithium-ion batteries (LIBs). Herein, a cross-linking polymeric network as a self-healing binder for Si anode is developed by in situ polymerization of tannic acid (TA) and polyacrylic acid (PAA) binder labelled as TA-c-PAA. The branched TA as a physical cross-linker complexes with PAA main chains through abundant dynamic hydrogen bonds, endowing the cross-linking TA-c-PAA binder with unique self-healing property and strong adhesion for Si anode. Benefiting from the mechanical robust and hard adhesion, the Si@TA-c-PAA electrode exhibits high reversible specific capacities (3250 mAh/g at 0.05C (1C = 4000 mA g-1)), excellent rate capability (1599 mAh/g at 2C), and impressive cycling stability (1742 mAh/g at 0.25C after 450 cycles). After Ex situ morphology characterization, in situ swelling analysis, and finite element simulation, it is found that the TA-c-PAA binder allows the Si anode to dissipate stress and prevent pulverization during lithiation and delithiation, thus the hydrogen bonds among interpenetrating network may be adaptable to the stress intensity. Our work paves a new avenue for the design of efficient and cost-effective binders for next-generation Si anode in LIBs.

Potential environmental and human health menace of spent graphite in lithium-ion batteries

The growing demand for lithium-ion batteries for portable electronics and electric vehicles results in a booming lithium battery market, leading to a concomitant increase in spent graphite. This research investigated the potential impacts of spent graphite on environmental and human health using standardized toxicity extraction and Life Cycle Impact Assessment models. The spent graphite samples were classified as hazardous waste due to the average nickel content of 337.14 mg/L according to Chinese regulations. Besides, cadmium and fluorine were the other elements that exceeded the regulations threshold. Easily ignored aluminum and heavy metal cobalt are other harmful elements according to the results of Life Cycle Impact Assessments. All the metallic harmful elements mainly exist in a transferable state. Thermogravimetry infrared spectrometry coupled with mass spectrometry was employed to recognize the emitted gases and explore gas emission behavior. Inorganic gases of CO, H2S, SO2, SO3, oxynitride, HCl, and fluoride-containing gases were detected. Sulfur-containing gases released from spent graphite were contributed by the residual sulfuric acid after leaching. The correlation between the evolution of emitted gases and the heating schedule was established simultaneously. The research comprehensively illustrates the pollution of spent graphite and provides assistance for the design of green recycling schemes for spent graphite.

Extending the electric vehicle battery first life: Performance beyond the current end of life threshold

Presently, Electric Vehicle batteries are considered to have reached the End of Life once their State of Health falls to 70-80%. However, this criteria is universal to all battery capacities and not based on the specific application requirements. To evaluate whether the End of Life can be extended below the current threshold, the impact of the Internal Resistance increase needs to be addressed. In this sense, this study employs a degradation aware electrothermal model to evaluate the battery performance for different use cases. The findings reveal that capacity constraints are the main cause of the End of Life, followed by power constraints. However, this is highly dependent on the battery capacity. Large capacity batteries tend to reach the End of Life for capacity constraints, whereas smaller ones show power limitations first. The temperature increase has not shown to be a restriction for any of the cases simulated. The decline in performance is for most cases (37.5% of the simulated ones) noticed below 70% State of Health, supporting that the first-life of most batteries can be extended without compromising the vehicle's performance. This is especially the case for most average drivers using large battery capacities, currently emerging on the market. The methodology proposed for the simulated cases can be extended to real time operation in the Battery Management System. Estimating the End of Life in this way can support the maximization of the first-life and only requires an appropriate use of the available data.

Effectively coupling of SnSe2nanosheet with N, Se co-doped carbon nanofibers as self-standing anode for lithium-ion batteries

Tin selenides possess layered structure and high theoretical capacity, which is considered as desirable anode material for lithium-ion batteries. However, its further development is limited by the low intrinsic electrical conductivity and sluggish reaction kinetics. Herein, a well-designed structure of SnSe2nanosheet attached on N, Se co-doped carbon nanofibers (SnSe2@CNFs) is fabricated as self-standing anodes for lithium-ion batteries. The integration of structural engineering and heteroatom doping enables accelerated electrons transfer and rapid ion diffusion for boosting Li+storage performance. Impressively, the flexible SnSe2@CNFs anodes exhibit inspiring capacity of 837.7 mAh g-1after 800 cycles at 1.2 C with coulombic efficiency almost 100% and superior rate performance 419.5 mAh g-1at 2.4 C. The kinetics analysis demonstrates the pseudocapacitive characteristic of SnSe2@CNFs promotes the storage property. This work sheds light on the hierarchical electrode construction towards high-performance energy storage applications.