Selective recovery of lithium and ammonium from spent lithium-ion batteries using intercalation electrodes

Recycling lithium-ion batteries has recently become a major concern. Ammonia leaching is commonly employed in such battery recycling methods since it has various advantages such as low toxicity and excellent selectivity toward precious metals. In this study, an electrochemical system with intercalation-type electrodes was used to investigate the selective recovery of lithium and ammonium from ammonia battery leachate. Using an activated carbon electrode as a counter electrode, the selectivity of lithium from the lithium manganese oxide (LMO) electrode and the selectivity of ammonium from the nickel hexacyanoferrate (NiHCF) electrode were examined within the system. The LMO//NiHCF system was next evaluated for lithium and ammonium recovery using a synthetic solution as well as real ammonia battery leachate. When compared to previous ammonium recovery methods, the results revealed good selectivity of lithium and ammonium from each LMO and NiHCF electrode with relatively low energy consumption for ammonium recovery (2.43 Wh g-N^-1). The average recovery capacity of lithium was 1.39 mmol g^-1 with a purity of up to 96.8% and the recovery capacity of ammonium was 1.09 mmol g^-1 with 97.8% purity from the pre-treated leachate. This electrochemical method together with ammonia leaching can be a promising method for selective resource recovery from spent lithium-ion batteries.

Two-step leaching of spent lithium-ion batteries and effective regeneration of critical metals and graphitic carbon employing hexuronic acid

Recovering precious metal ions like Co, Li, Mn, and Ni from discarded lithium-ion batteries (LIBs) has significant environmental and economic benefits. Also, graphite will be in high demand in the coming years due to the development of LIBs for use in electric vehicles (EVs) and the need for it for electrodes in a variety of energy storage devices. However, it has been overlooked during the recycling of used LIBs, which resulted in resource waste and environmental pollution. In this work, a comprehensive and environmentally friendly approach for recycling critical metals as well as graphitic carbon from discarded LIBs was proposed. To optimize the leaching process, various leaching parameters were investigated by employing hexuronic acid or ascorbic acid. The feed sample was analyzed using XRD, SEM-EDS, and a Laser Scattering Particle Size Distribution Analyzer to determine the phases, morphology, and particle size. 100% of Li and 99.5% of Co were leached at the optimum conditions of 0.8 mol L^-1 ascorbic acid, a particle size of -25 μm, 70 °C, 60 min of leaching time, and 50 g L^-1 of S/L ratio. A detailed study of the leaching kinetics was carried out. The leaching process was found to be well-fitted with the surface chemical reaction model based on the findings of temperature, acid concentration, and particle size variations. To obtain pure graphitic carbon after the initial leaching, the leached residue was subjected to further leaching with various acids (HCl, H₂SO₄, and HNO₃). The Raman spectra, XRD, TGA, and SEM-EDS analysis of the leached residues following the two-step leaching process were examined to exemplify the quality of the graphitic carbon.

Charge Carriers for Aqueous Dual-Ion Batteries

Environmental and safety concerns of energy storage systems call for application of aqueous battery systems which have advantages of low cost, environmental benignity, safety, and easy assembling. Among the aqueous battery systems, aqueous dual-ion batteries (ADIBs) provide high possibility for achieving excellent battery performance. Compared with the "rocking chair" batteries with only one type of carrier involved in the charging and discharging, ADIBs with both cations and anions as charge carriers possess diverse selections of electrodes and electrolytes. Charge carriers are the basis of the configuration of ADIBs. In this Review, cations and anions that could be applied in ADIBs are demonstrated with corresponding electrode materials and favorable electrolytes. Some insertion mechanisms are emphasized to provide insights for the possibilities to enhance the practical performances of ADIBs.

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

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

Recycling Valuable Metals from Spent Lithium-Ion Batteries Using Carbothermal Shock Method

Pyrometallurgy technique is usually applied as a pretreatment to enhance the leaching efficiencies in the hydrometallurgy process for recovering valuable metals from spent lithium-ion batteries. However, traditional pyrometallurgy processes are energy and time consuming. Here, we report a carbothermal shock (CTS) method for reducing LiNi_0.3 Co_0.2 Mn_0.5 O₂ (NCM325) cathode materials with uniform temperature distribution, high heating and cooling rates, high temperatures, and ultrafast reaction times. Li can be selectively leached through water leaching after CTS process with an efficiency of >90 %. Ni, Co, and Mn are recovered by dilute acid leaching with efficiencies >98 %. The CTS reduction strategy is feasible for various spent cathode materials, including NCM111, NCM523, NCM622, NCM811, LiCoO₂ , and LiMn₂ O₄ . The CTS process, with its low energy consumption and potential scale application, provides an efficient and environmentally friendly way for recovering spent lithium-ion batteries.

Ultrafast materials synthesis and manufacturing techniques for emerging energy and environmental applications

Energy and environmental issues have attracted increasing attention globally, where sustainability and low-carbon emissions are seriously considered and widely accepted by government officials. In response to this situation, the development of renewable energy and environmental technologies is urgently needed to complement the usage of traditional fossil fuels. While a big part of advancement in these technologies relies on materials innovations, new materials discovery is limited by sluggish conventional materials synthesis methods, greatly hindering the advancement of related technologies. To address this issue, this review introduces and comprehensively summarizes emerging ultrafast materials synthesis methods that could synthesize materials in times as short as nanoseconds, significantly improving research efficiency. We discuss the unique advantages of these methods, followed by how they benefit individual applications for renewable energy and the environment. We also highlight the scalability of ultrafast manufacturing towards their potential industrial utilization. Finally, we provide our perspectives on challenges and opportunities for the future development of ultrafast synthesis and manufacturing technologies. We anticipate that fertile opportunities exist not only for energy and the environment but also for many other applications.

A sustainable approach for selective recovery of lithium from cathode materials of spent lithium-ion batteries by induced phase transition

Recycling of spent lithium-ion batteries (LIBs) has attracted widespread attention because of their dual attributes to environmental protection and resource conservation. Utilization of strong corrosive acids is currently the preferred way to recover valuable metals from spent LIBs, but the extensive use of chemical reagents can pose serious environmental risks. Herein, this research proposes a green process for selective recovery of lithium using the material of spent LIBs itself without adding exogenous reagents, mechanochemistry induced phase transition. The leaching efficiency of Li can reach 94% by employing the copper foil separated from spent LIBs as the co-grinding additive during the mechanochemical reaction process. Then, the high value LiOH·H₂O can be prepared through direct evaporation and crystallization without adding any precipitant. Meanwhile, cobalt is almost remained in the leaching residue which can be recovered through a step-by-step separation process. XRD, XPS, and SEM-EDS characterizations show that LiCoO₂ and copper foil are transformed into the soluble Li₂O, and insoluble CuO and CoO under the mechanical force. Finally, the soluble Li₂O is dissolved in water to prepare the LiOH solution, and the insoluble CuO and CoO are transformed into Cu₂O and Co(OH)₂. On the basis of the experimental investigation, it is proven that the proposed process is suitable for selectively recovering Li from all types of cathode materials without generating salty wastewater or introducing chemical reagents. Thus, the proposed approach can ensure the efficient recovery of valuable metals from spent LIBs while avoiding the potential threat to the environment and human health.

Flash Recycling of Graphite Anodes

The ever-increasing production of commercial lithium-ion batteries (LIBs) will result in a staggering accumulation of waste when they reach their end of life. A closed-loop solution, with effective recycling of spent LIBs, will lessen both the environmental impacts and economic cost of their use. Presently, <5% of spent LIBs are recycled and the regeneration of graphite anodes has, unfortunately, been mostly overlooked despite the considerable cost of battery-grade graphite. Here, an ultrafast flash recycling method to regenerate the graphite anode is developed and valuable battery metal resources are recovered. Selective Joule heating is applied for only seconds to efficiently decompose the resistive impurities. The generated inorganic salts, including lithium, cobalt, nickel, and manganese, can be easily recollected from the flashed anode waste using diluted acid, specifically 0.1 m HCl. The flash-recycled anode preserves the graphite structure and is coated with a solid-electrolyte-interphase-derived carbon shell, contributing to high initial specific capacity, superior rate performance, and cycling stability, when compared to anode materials recycled using a high-temperature-calcination method. Life-cycle-analysis relative to current graphite production and recycling methods indicate that flash recycling can significantly reduce the total energy consumption and greenhouse gas emission while turning anode recycling into an economically advantageous process.

Applications of Spent Lithium Battery Electrode Materials in Catalytic Decontamination: A Review

For a large amount of spent lithium battery electrode materials (SLBEMs), direct recycling by traditional hydrometallurgy or pyrometallurgy technologies suffers from high cost and low efficiency and even serious secondary pollution. Therefore, aiming to maximize the benefits of both environmental protection and e-waste resource recovery, the applications of SLBEM containing redox-active transition metals (e.g., Ni, Co, Mn, and Fe) for catalytic decontamination before disposal and recycling has attracted extensive attention. More importantly, the positive effects of innate structural advantages (defects, oxygen vacancies, and metal vacancies) in SLBEMs on catalytic decontamination have gradually been unveiled. This review summarizes the pretreatment and utilization methods to achieve excellent catalytic performance of SLBEMs, the key factors (pH, reaction temperature, coexisting anions, and catalyst dosage) affecting the catalytic activity of SLBEM, the potential application and the outstanding characteristics (detection, reinforcement approaches, and effects of innate structural advantages) of SLBEMs in pollution treatment, and possible reaction mechanisms. In addition, this review proposes the possible problems of SLBEMs in practical decontamination and the future outlook, which can help to provide a broader reference for researchers to better promote the implementation of “treating waste to waste” strategy.

Assessment of environmental sustainability of nickel required for mobility transition

Nickel (Ni) in batteries (e.g., nickel-metal hydride battery (NiMH), lithium nickel cobalt aluminum oxide (NCA) and lithium nickel manganese cobalt oxide (NMC)) aim to ensure higher energy density and greater storage capacity. Two typical layered nickel-rich ternary cathode materials, NCA and NMC, are commercialized as advanced lithium-ion batteries (LiBs) for electric vehicles (EVs). The technology of those batteries has been improving by steadily increasing the nickel content in each cathode generation. In this study, we consider two types of batteries having a composite cathode made of Li [Ni0.80Co0.1Al0.1]O2, and Li [Ni0.33Mn0.33Co0.33]O2, which are the most common cathode materials for LiBs in EVs since 2010 and their functional recycling is performed. The increasing use of nickel in battery technologies has resulted in the continuous growth of demand for nickel over recent years. Nickel was added to the list of critical materials by the United States Geological Survey (USGS) already in 2021. Unfortunately now, the sustainable supply of nickel is even at higher risk due to the sanctions-related disruption of supplies from Russia. Therefore, enhancing the circularity of nickel starts to be vital for many economies. Demand for recycled nickel is growing, however, a systematic analysis of the sustainability of its recycling is still missing. Therefore, we provide a comprehensive assessment of the sustainability of the global primary and secondary production of nickel. Using system dynamics modelling integrated with geometallurgy principles and by analyzing the processing routes (pyrometallurgical and hydrometallurgical processes), we quantify the key environmental concerns across the life cycle of primary and secondary nickel required for sustainable mobility transition. Energy consumption, water use, and related emissions are assessed for all stages of the nickel supply chain, from mining to recycling. Our analysis shows the possibility of reducing the emissions by around 4.7 mt for GHG, 6.9 kt for PM2.5, 34.3 t for BC, 2.8 kt for CH4, 7.5 kt for CO, 3.3 mt for CO2, 169.9 t for N2O, 3.8 kt for NOx, 11.8 kt for PM10, 104.8 t for POC, 1.6 mt for SOx, and 232.5 t for VOC by engaging in the secondary production of nickel through the recycling of batteries. However, identical growth rate of energy consumption and water use compared to nickel mass flows means no technical progress has been achieved in different stages of the nickel supply chain towards sustainability over the period 2010–2030. Therefore, an improvement in technology is needed to save energy and water in nickel production processes. The results and findings of this study contribute to a better understanding of the necessity for improving closed-loop supply chain policies for nickel.

One-step selective separation and efficient recovery of valuable metals from mixed spent lithium batteries in the phosphoric acid system

The recovery of valuable elements in spent lithium-ion batteries (LIBs) has attracted more and more attention. Efficient recovery of valuable elements from spent LIBs with lower consumption and shorter process is the target that people have been pursuing. In this study, the valuable metals (Ni, Co, Mn and Li) and FePO₄ products are simultaneously recovered from mixed spent LiNi_xCo_yMn_zO₂ and LiFePO₄ in one step under the optimized condition of 0.88 M H₃PO₄, a mass ratio of LFP/NCM of 2:1, a L/S ratio of 33:1 and 80 ℃ for 120 min without additional auxiliary reagents. Over 60 % of acid consumption is reduced and the process of adjusting pH is avoidable. The leaching efficiencies of the valuable elements reach up to 99.1 % for Ni, 98.9 % for Co, 99.6 % for Li and 97.3 % for Mn. Almost all of Fe is precipitated as FePO₄·2H₂O. By means of the empirical model, the research on leaching kinetics demonstrates that the leaching reaction is internal diffusion-controlled with the apparent activation energy of valuable metals less than 30 kJ/mol. Furthermore, the redox reaction mechanism between spent LiBs has been explored. And the intrinsic driving force in the phosphoric acid system is found out. This finding may provide an innovative and selective recycling method for valuable elements from mixed spent LIBs with high economic benefit and fewer environmental footprints.

A Fast-Charging and High-Temperature All-Organic Rechargeable Potassium Battery

Developing fast-charging, high-temperature, and sustainable batteries is critical for the large-scale deployment of energy storage devices in electric vehicles, grid-scale electrical energy storage, and high temperature regions. Here, a transition metal-free all-organic rechargeable potassium battery (RPB) based on abundant and sustainable organic electrode materials (OEMs) and potassium resources for fast-charging and high-temperature applications is demonstrated. N-doped graphene and a 2.8 m potassium hexafluorophosphate (KPF₆ ) in diethylene glycol dimethyl ether (DEGDME) electrolyte are employed to mitigate the dissolution of OEMs, enhance the electrode conductivity, accommodate large volume change, and form stable solid electrolyte interphase in the all-organic RPB. At room temperature, the RPB delivers a high specific capacity of 188.1 mAh g^-1 at 50 mA g^-1 and superior cycle life of 6000 and 50000 cycles at 1 and 5 A g^-1 , respectively, demonstrating an ultra-stable and fast-charging all-organic battery. The impressive performance at room temperature is extended to high temperatures, where the high-mass-loading (6.5 mg cm^-2 ) all-organic RPB exhibits high-rate capability up to 2 A g^-1 and a long lifetime of 500 cycles at 70-100 °C, demonstrating a superb fast-charging and high-temperature battery. The cell configuration demonstrated in this work shows great promise for practical applications of sustainable batteries at extreme conditions.

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

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

Organic Electrolytes Recycling From Spent Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are regarded to be the most promising electrochemical energy storage device for portable electronics as well as electrical vehicles. However, due to their limited-service life, tons of spent LIBs are expected to be produced in the recent years. Suitable recycling technology is therefore becoming more and more important as improper treatment of spent LIBs, especially the aged organic electrolyte, can cause severe environmental pollution and threats to human health. The organic solvents and high concentration of lithium salts in aged electrolytes are always sensitive toward water and air, which would easily hydrolyze and decompose into toxic fluorine-containing compounds, leading to severe fluorine pollution of the surrounding environment. Hence, recycling aged electrolytes from spent LIBs is an efficient way to avoid this potential risk to the environment. However, several issues inhibit the realization of electrolyte recycling, including the volatile, inflammable, and toxic nature of the electrolytes, the difficulty to extract electrolytes from the electrodes and separators, and various electrolyte compositions inside LIBs from different applications and companies. Herein, the current progress in recycling methods for aged electrolytes from spent LIBs is summarized and perspectives on future development of electrolyte recycling are presented.

Building Practical High-Voltage Cathode Materials for Lithium-Ion Batteries

It has long been a global imperative to develop high-energy-density lithium-ion batteries (LIBs) to meet the ever-growing electric vehicle market. One of the most effective strategies for boosting the energy density of LIBs is to increase the output voltage, which largely depends upon the cathode materials. As the most-promising cathodes for high-voltage LIBs (>4 V vs Li/Li⁺ ), four major categories of cathodes including lithium-rich layered oxides, nickel-rich layered oxides, spinel oxides, and high-voltage polyanionic compounds still encounter severe challenges to realize the improvement of output voltage while maintaining high capacity, fast rate capability, and long service life. This review focuses on the key links in the development of high-voltage cathode materials from the lab to industrialization. First, the failure mechanisms of the four kinds of materials are clarified, and the optimization strategies, particularly solutions that are easy for large-scale production, are considered. Then, to bridge the gap between lab and industry, the cost management, safety assessment, practical battery-performance evaluation, and sustainability of the battery technologies, are discussed. Finally, tough challenges and promising strategies for the commercialization of high-voltage cathode materials are summarized to promote the large-scale application of LIBs with high energy densities.

An emission-free controlled potassium pyrosulfate roasting-assisted leaching process for selective lithium recycling from spent Li-ion batteries

Recycling critical metals from spent Li-ion batteries (LIBs) is important for the overall sustainability of future batteries. This study reports an improved sulfation roasting technology to efficiently recycle Li and Co from spent LiCoO₂ LIBs using potassium pyrosulfate as sulfurizing reagent. By sulfation roasting, LiCoO₂ was converted into water-soluble lithium potassium sulfate and water-insoluble cobalt oxide. Under optimal conditions, 98.51% Li was leached in water, with a selectivity of 99.86%. More importantly, sulfur can be recirculated thoroughly, and the sulfur atomic efficiency can be significantly enhanced by controlling the amount of potassium pyrosulfate. Li ions from the water leaching process were recovered by chemical precipitation. Furthermore, application of this technology to other spent LIBs, such as LiMn₂O₄ and LiNi_0.5Co_0.2Mn_0.3O₂, verified its effectiveness for selective recovery Li. These findings can provide some inspiration for high efficiency and environmentally friendly recovery metal from spent LIBs.

NaOH-assisted low-temperature roasting to recover spent LiFePO4 batteries

Decreasing the operating temperature of pyrometallurgical methods for recycling spent lithium-ion batteries (LIBs) is key to reducing energy consumption and cost. Herein, a NaOH-assisted low-temperature roasting approach is proposed to recover spent LiFePO₄. During roasting, NaOH acts as an oxidizing agent to oxidize Fe (II) to Fe₃O₄ at 150°C, thus collapsing its stable olivine structure while PO₄^3- capturing Li⁺ and Na⁺ to form Li₂NaPO₄ and LiNa₅(PO₄)₂. The obtained Fe₃O₄ is then separated, and the resulting Li salt can be further recovered as Li₃PO₄ with a Li recovery efficiency of 96.7 % and a purity of 99.9 %. Economic and environmental analysis based on the EverBatt model shows that this low-temperature strategy reduces energy consumption and greenhouse gas (GHG) emissions, thus increasing the potential profit. Overall, NaOH-assisted low-temperature roasting is a prospective strategy that broadens the application of NaOH as an oxidant and opens up a new avenue for decreasing the temperature of recovering spent LiFePO₄ by pyrometallurgy.

A green and sustainable strategy toward lithium resources recycling from spent batteries

Recycling lithium from spent batteries is challenging because of problems with poor purity and contamination. Here, we propose a green and sustainable lithium recovery strategy for spent batteries containing LiFePO₄, LiCoO₂, and LiNi_0.5Co_0.2Mn_0.3O₂ electrodes. Our proposed configuration of "lithium-rich electrode || LLZTO@LiTFSI+P3HT || LiOH" system achieves double-side and roll-to-roll recycling of lithium-containing electrode without destroying its integrity. The LiTFSI+P3HT-modified LLZTO membrane also solves the H⁺/Li⁺ exchange problem and realizes a waterproof protection of bare LLZTO in the aqueous working environment. On the basis of these advantages, our system shows high Li selectivity (97%) and excellent Faradaic efficiency (≥97%), achieving high-purity (99%) LiOH along with the production of H₂. The Li extraction processes for spent LiFePO₄, LiNi_0.5Co_0.2Mn_0.3O₂, and LiCoO₂ batteries is shown to be economically feasible. Therefore, this study provides a previously unexplored technology with low energy consumption as well as high economic and environmental benefits to realize sustainable lithium recycling from spent batteries.

Advances and challenges in anode graphite recycling from spent lithium-ion batteries

Spent lithium-ion batteries (LIBs) have been one of the fast-growing and largest quantities of solid waste in the world. Spent graphite anode, accounting for 12-21 wt% of batteries, contains metals, binders, toxic, and flammable electrolytes. The efficient recovery of spent graphite is urgently needed for environmental protection and resource sustainability. Recently, more and more studies have been focused on spent graphite recycling, while the advance and challenges are rarely summarized. Hence, this study made a comprehensive review of graphite recycling including separation, regeneration, and synthesis of functional materials. Firstly, the pretreatment of graphite separation was overviewed. Then, the spent graphite regeneration methods such as leaching, pyrometallurgy, their integration processes, etc. were systematically introduced. Furthermore, the modification strategies to enhance the electrochemical performance were discussed. Subsequently, we reviewed in detail the synthesis of functional materials using spent graphite for energy and environmental applications including graphene, adsorbents, catalysts, capacitors, and graphite/polymer composites. Meanwhile, we briefly compared the economic and environmental benefits of graphite regeneration and other functional materials production. Finally, the technical bottlenecks and challenges for spent graphite recycling were summarized and some future research directions were proposed. This review contributes to spent LIBs recycling more efficiently and profitably in the future.

A Ternary Molten Salt Approach for Direct Regeneration of LiNi0.5 Co0.2 Mn0.3 O2 Cathode

Recycling spent lithium-ion batteries (LIBs) is an urgent task in view of the resource shortage and environmental concerns. Here, a facile ternary molten salt approach is presented for efficiently regenerating the LiNi_0.5 Co_0.2 Mn_0.3 O₂ (NCM523) cathode of spent LIBs. Such an approach involves the treatment of spent cathode powder in the ternary molten salt at a moderate temperature (400 °C) and subsequent annealing in oxygen. The Li loss and degraded phases in spent NCM that cause the capacity decay can be fully remedied after the regeneration process. As a result, the regenerated cathode delivers a reversible capacity of 160 mAh g^-1 at 0.5 C with retention of 93.7% after 100 cycles and maintains a high capacity of 132 mAh g^-1 at a high rate of 5 C. The electrochemical performance of regenerated NCM cathode is compared favorably to the fresh NCM cathode, which demonstrates the feasibility of the molten salt approach to directly regenerate spent NCM cathode.

A Minireview on the Regeneration of NCM Cathode Material Directly from Spent Lithium-Ion Batteries with Different Cathode Chemistries

Research on the regeneration of cathode materials of spent lithium-ion batteries for resource reclamation and environmental protection is attracting more and more attention today. However, the majority of studies on recycling lithium-ion batteries (LIBs) placed the emphasis only on recovering target metals, such as Co, Ni, and Li, from the cathode materials, or how to recycle spent LIBs by conventional means. Effective reclamation strategies (e.g., pyrometallurgical technologies, hydrometallurgy techniques, and biological strategies) have been used in research on recycling used LIBs. Nevertheless, none of the existing reviews of regenerating cathode materials from waste LIBs elucidated the strategies to regenerate lithium nickel manganese cobalt oxide (NCM or LiNixCoyMnzO2) cathode materials directly from spent LIBs containing other than NCM cathodes but, at the same time, frequently used commercial cathode materials such as LiCoO2 (LCO), LiFePO4 (LFP), LiMn2O4 (LMO), etc. or from spent mixed cathode materials. This review showcases the strategies and techniques for regenerating LiNixCoyMnzO2 cathode active materials directly from some commonly used and different types of mixed-cathode materials. The article summarizes the various technologies and processes of regenerating LiNixCoyMnzO2 cathode active materials directly from some individual cathode materials and the mixed-cathode scraps of spent LIBs without their preliminary separation. In the meantime, the economic benefits and diverse synthetic routes of regenerating LiNixCoyMnzO2 cathode materials reported in the literature are analyzed systematically. This minireview can lay guidance and a theoretical basis for restoring LiNixCoyMnzO2 cathode materials.

A Systematic Analysis of the Costs and Environmental Impacts of Critical Materials Recovery from Hybrid Electric Vehicle Batteries in the U.S

Critical materials such as rare earth underpin technologies needed for a decarbonized global economy. Recycling can mitigate the supply risks created by the increasing demand and net import dependence, and enable a circular economy for critical materials. In this study, we analyze the feasibility and life-cycle impacts of recovering critical materials from spent nickel metal hydride batteries from hybrid electric vehicles in the U.S., accounting for stocks, battery scrappage, and end-of-life reverse logistics, given uncertain future availability scenarios. Our results show that the total collection and recycling costs depend strongly on future battery availability, with marginal costs exceeding marginal revenues when the availability of spent batteries declines. We quantify the potential of recycling to reduce primary imports, as well as the accompanying climate change and resource impacts. We explore the underlying reverse logistics infrastructure required for battery recycling and evaluate strategies for reducing associated capital investment risk.

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We assess techno-economic and life-cycle impacts of large-scale HEV battery recycling

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Recycling offsets primary critical material demand with lower environmental impacts

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Flexible strategies mitigate investment risk from uncertain future battery availability

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Marginal cost analysis can inform strategies for incentivizing collection and recycling

Regeneration and utilization of graphite from the spent lithium-ion batteries by modified low-temperature sulfuric acid roasting

Recycling spent graphite in spent lithium-ion batteries (LIBs) is crucial for lacking high-quality graphite and environmental protection. Here, an environmentally friendly and economical modified method based on sulfate roasting was proposed to recycle spent graphite via low temperature roasting at 250 °C with sodium fluoride as an assistant additive. Recycling leads to graphite with a high purity of 99.55 % and chemical structures for energy storage. Batteries manufactured in regenerated graphite deliver a high initial charge capacity of 333.9 mAh/g with an initial columbic efficiency of 85.71% and excellent capacity retention of 91.2% after 400 cycles. In addition, the waste produced in the method could be well treated, and by-products 177 g of sodium sulfate would be collected per 1 kg spent graphite and NaF, equivalent to 78.95% of the added amount obtained through wastewater and exhaust gas, respectively. The regenerated sodium fluoride will be re-applied to the recovery spent graphite. The loop-closed method shows great promise for the industrial-scale recycling of spent graphite for energy storage applications.

Efficient separation and recovery of lithium through volatilization in the recycling process of spent lithium-ion batteries

Spent lithium-ion batteries (LIBs) comprise different kinds of valuable metals with recovery and reuse value. Aiming to address the difficulty of recycling lithium from spent LIBs through conventional pyrometallurgy, a new method of high-efficiency separation and recovery of lithium through volatilization is proposed. In this new method, spent LIBs as the raw material, copper slag as the only flux and CaCl₂ as an additive are utilized to recover lithium from spent LIBs. Under the optimal conditions, the volatilization rate of Li was 96.87%. During the smelting process, lithium is volatilized into the gas phase in the form of LiCl, where lithium can be recycled from the dust. In light of the experimental results, the addition of CaCl₂ contributes to the formation of LiCl. The kinetics study showed that the volatilization of LiCl was controlled by an interfacial chemical reaction, and the apparent activation energy was 42.57 kJ/mol. In addition, Li₂CO₃ could be obtained from lithium-containing dust using a precipitation process. This method achieves efficient separation of lithium during the reduction smelting process. The phase transformation and kinetics of the separation process were investigated, and reaction mechanism was revealed. Importantly, the novel process provides new ideas and perspectives for the separation of lithium from spent LIBs through a pyrometallurgical process.

Mechanochemically assisted persulfate activation for the facile recovery of metals from spent lithium ion batteries

A novel mechanochemically assisted persulfate activation method was proposed in this study to enhance the leaching of valuable metals from lithium-ion batteries by combining ball-milling, advanced oxidation processes and sucrose reduction. By optimizing leaching parameters including temperature, pH, milling time and solid-to-liquid ratio, high leaching efficiencies of 97.1%, 94.0%, 87.6% and 93.8% can be achieved for Li, Ni, Co and Mn respectively. In the mechanochemical process, the breakage of covalent bonds in cathode material is facilitated by free radicals generated from zero valent iron activated ammonia persulfate as well as mechanochemical activation. To further explore the role of free radicals, the mechanism of ammonia persulfate activation by zero valent iron was elucidated, and SO₄^•- was identified as the dominant reactive oxygen species in the mechanochemical process. Meanwhile, the synergistic effect of mechanochemically driven crystal dissolution and sulfate radical facilitated bond cleavage was revealed by ab initio molecular dynamics simulation. Moreover, the released metal was reduced by sucrose to a lower valent state of high solubility to promote transfer to the aqueous phase during the subsequent leaching process with dilute sulfuric acid. In this work, the insight on the mechanism of mechanochemical processes strengthened by free radicals may provide an inspiration for the recovery of valuable metals from LIBs.

Double-edged role of interlayer water on Li+ extraction from ultrahigh Mg2+/Li+ ratio brines using Li/Al-LDHs

Lithium-aluminum layered double hydroxides (Li/Al-LDHs) are the only industrial adsorbents for Li⁺ extraction from Mg²⁺/Li⁺ ratio brines dependent on the special neutral desorption without dissolution damage. In this work, Li/Al-LDHs with different interlayer water contents were designed for the investigation of correlation between interlayer water and Li⁺ adsorption performances in high Mg²⁺/Li⁺ ratio brines. On the one hand, the Li⁺ adsorption capacity of Li/Al-LDHs in the Qarham Salt Lake old brine with a Mg²⁺/Li⁺ ratio exceeding 300 presented a positive correlative relation with the interlayer water content, rising from 1.05 mg/g to 7.89 mg/g as the interlayer water content increased from 5.52% to 18.18%. On the other hand, the interlayer water content would not affect the structure stability of Li/Al-LDHs, while the interlayer spacing was lessened with less interlayer water resulting in an uptrend to the adsorption selectivity on account of the depressed confinement effect. The density functional theory (DFT) calculation further indicated that LiCl was easier to enter the structure of Li/Al-LDHs with more interlayer water in view of the greater interaction energy.

Environmental impact assessment of second life and recycling for LiFePO4 power batteries in China

The number of spent lithium-ion batteries (LIBs) will increase exponentially in the coming decade with the retirement of electric vehicles (EVs). There is a knowledge gap in assessing the environmental impact of different terminal disposal paths for EV LIBs in China. Here, we take representative lithium iron phosphate (LFP) power batteries as example and carry out a bottom-up life cycle assessment (LCA). The life cycle stages of battery manufacturing, use, second life and battery recycling are considered to conduct a cradle-to-grave environmental impact analysis. To investigate the environmental benefits of end-of-life (EoL) stage for LFP batteries, two EoL management scenarios are considered in this study. The first one combines second life application with battery recycling, and the second recycles the retired batteries directly after EV use. The result shows that the secondary application of retired LFP batteries in energy storage systems (ESSs) can effectively reduce the net environmental impact of LIB life cycle, especially for fossil fuel depletion. When the service life of secondary use is increased from 1 year to 10 years, the environmental benefits of different impact categories will increase by 0.24-4.62 times. For direct recycle scenario, recycling retired LFP batteries can save more than 30% of metal resources. By comparison, we find that recycling lithium nickel manganese cobalt oxide (NCM) batteries has greater environmental benefits than recycling LFP batteries for all impact categories. When considering the environmental benefits at the EoL stage, most life cycle environmental impact is likely to be offset or even show positive benefits if more than 50% of power batteries can be reused in ESSs after retirement.

Preparation of single-crystal ternary cathode materials via recycling spent cathodes for high performance lithium-ion batteries

With the rapid consumption of lithium-ion batteries (LIBs), the recycling of spent LIBs is becoming imperative. However, the development of effective and environmentally friendly methods towards the recycling of spent LIBs, especially waste electrode materials, still remains a great challenge. Herein, on the basis of a Li-based molten salt, we have developed a facile and effective strategy to recycle spent polycrystalline ternary cathode materials into single-crystal cathodes. The regenerated plate-like single-crystal LiNi_0.6Co_0.2Mn_0.2O₂ material with exposed {010} planes achieves an excellent rate performance and outstanding cycling stability. In particular, a high capacity of 155.1 mA h g^-1 and a superior capacity retention of 94.3% can be achieved by the recycled cathode material even after 240 cycles at 1 C. Meanwhile the single-crystal structure can be well reserved without any cracks or pulverization being observed. Moreover, this recycling method can be expanded to recycle other waste Ni-Co-Mn ternary cathode materials (NCM) or their mixtures for producing high-performance single-crystal cathode materials, demonstrating its versatility and flexibility in practical applications. Therefore, the strategy of converting spent NCM cathodes into single-crystal ones with satisfactory electrochemical performance may open up a cost-effective pathway for resolving the issues caused by the large amounts of spent LIBs, thus facilitating the sustainable development of LIBs.

Recycling of Lead Pastes from Spent Lead–Acid Batteries: Thermodynamic Constraints for Desulphurization

Lead–acid batteries are important to modern society because of their wide usage and low cost. The primary source for production of new lead–acid batteries is from recycling spent lead–acid batteries. In spent lead–acid batteries, lead is primarily present as lead pastes. In lead pastes, the dominant component is lead sulfate (PbSO4, mineral name anglesite) and lead oxide sulfate (PbO•PbSO4, mineral name lanarkite), which accounts for more than 60% of lead pastes. In the recycling process for lead–acid batteries, the desulphurization of lead sulfate is the key part to the overall process. In this work, the thermodynamic constraints for desulphurization via the hydrometallurgical route for recycling lead pastes are presented. The thermodynamic constraints are established according to the thermodynamic model that is applicable and important to recycling of lead pastes via hydrometallurgical routes in high ionic strength solutions that are expected to be in industrial processes. The thermodynamic database is based on the Pitzer equations for calculations of activity coefficients of aqueous species. The desulphurization of lead sulfates represented by PbSO4 can be achieved through the following routes. (1) conversion to lead oxalate in oxalate-bearing solutions; (2) conversion to lead monoxide in alkaline solutions; and (3) conversion to lead carbonate in carbonate solutions. Among the above three routes, the conversion to lead oxalate is environmentally friendly and has a strong thermodynamic driving force. Oxalate-bearing solutions such as oxalic acid and potassium oxalate solutions will provide high activities of oxalate that are many orders of magnitude higher than those required for conversion of anglesite or lanarkite to lead oxalate, in accordance with the thermodynamic model established for the oxalate system. An additional advantage of the oxalate conversion route is that no additional reductant is needed to reduce lead dioxide to lead oxide or lead sulfate, as there is a strong thermodynamic force to convert lead dioxide directly to lead oxalate. As lanarkite is an important sulfate-bearing phase in lead pastes, this study evaluates the solubility constant for lanarkite regarding the following reaction, based on the solubility data, PbO•PbSO4 + 2H+ ⇌ 2Pb2+ + SO42− + H2O(l).

Surface Growth and Intergranular Separation of Polycrystalline Particles for Regeneration of Stable Single-Crystal Cathode Materials

The direct regeneration technology has been developed because of its short-range, high efficiency, and green characteristics. However, the existing direct regeneration method is hardly applied in collaborative reconstruction of the damaged crystal and particle of spent polycrystalline layered materials. The single-crystal regeneration with restructuring the morphology and crystal structure was herein achieved for the first time by low-temperature lithium supplementation followed with high-temperature molten salt conversion, which could effectively solve the structural defects of spent polycrystalline layered materials. We found that the realization of single-crystal regeneration with the molten salt process is attributable to that the original crystal growth of primary particles in the polycrystal transfer to the subsequent division along the grain boundary. At the test conditions of 25 °C and 2.8-4.3 V, the capacity retention capacity of the regenerated single-crystal materials reach 83.3% after 200 cycles at 1 C, which is much higher than 20.0% for conventional direct lithiation regeneration and 61.6% for low-temperature molten salt regeneration. Interestingly, the regenerated single-crystal NCM622 in the graphite full-cell test displays a capacity retention rate of 85.24% after 800 cycles at a rate of 1 C at 2.5-4.35 V. This work opens up a new way for the direct regeneration of spent polycrystalline layered cathode materials.

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.

Preferential Extraction of Lithium from Spent Cathodes and the Regeneration of Layered Oxides for Li/Na-Ion Batteries

The preferentially selective extraction of Li⁺ from spent layered transition metal oxide (LiMO₂, M = Ni, Co, Mn, etc.) cathodes has attracted extensive interest based on economic and recycling efficiency requirements. Presently, the efficient recycling of spent LiMO₂ is still challenging due to the element loss in multistep processes. Here, we developed a facile strategy to selectively extract Li⁺ from LiMO₂ scraps with stoichiometric H₂SO₄. The proton exchange reaction could be driven using temperature, accompanied by the generation of soluble Li₂SO₄ and MOOH precipitates. The extraction mechanism includes a two-stage evolution, including dissolution and ion exchange. As a result, the extraction rate of Li⁺ is over 98.5% and that of M ions is less than 0.1% for S-NCM. For S-LCO, the selective extraction result is even better. Finally, Li₂CO₃ products with a purity of 99.68% can be prepared from the Li⁺-rich leachate, demonstrating lithium recovery efficiencies as high as 95 and 96.3% from NCM scraps and S-LCO scraps, respectively. In the available cases, this work also represents the highest recycling efficiency of lithium, which can be attributed to the high leaching rate and selectivity of Li⁺, and even demonstrates the lowest reagent cost. The regenerated LiNi_0.5Co_0.24Mn_0.26O₂ and Na_1.01Li_0.001Ni_0.38Co_0.18Mn_0.44O₂ cathodes also deliver a decent electrochemical performance for Li-ion batteries (LIBs) and Na-ion batteries (NIBs), respectively. Our current work offers a facile, closed-loop, and scalable strategy for recycling spent LIB cathodes based on the preferentially selective extraction of Li⁺, which is superior to the other leaching technology in terms of its cost and recycling yield.

Green Recycling Methods to Treat Lithium-Ion Batteries E-Waste: A Circular Approach to Sustainability

E-waste generated from end-of-life spent lithium-ion batteries (LIBs) is increasing at a rapid rate owing to the increasing consumption of these batteries in portable electronics, electric vehicles, and renewable energy storage worldwide. On the one hand, landfilling and incinerating LIBs e-waste poses environmental and safety concerns owing to their constituent materials. On the other hand, scarcity of metal resources used in manufacturing LIBs and potential value creation through the recovery of these metal resources from spent LIBs has triggered increased interest in recycling spent LIBs from e-waste. State of the art recycling of spent LIBs involving pyrometallurgy and hydrometallurgy processes generates considerable unwanted environmental concerns. Hence, alternative innovative approaches toward the green recycling process of spent LIBs are essential to tackle large volumes of spent LIBs in an environmentally friendly way. Such evolving techniques for spent LIBs recycling based on green approaches, including bioleaching, waste for waste approach, and electrodeposition, are discussed here. Furthermore, the ways to regenerate strategic metals post leaching, efficiently reprocess extracted high-value materials, and reuse them in applications including electrode materials for new LIBs. The concept of "circular economy" is highlighted through closed-loop recycling of spent LIBs achieved through green-sustainable approaches.

Assessment of recycling methods and processes for lithium-ion batteries

This review discusses physical, chemical, and direct lithium-ion battery recycling methods to have an outlook on future recovery routes. Physical and chemical processes are employed to treat cathode active materials which are the greatest cost contributor in the production of lithium batteries. Direct recycling processes maintain the original chemical structure and process value of battery materials by recovering and reusing them directly. Mechanical separation is essential to liberate cathode materials that are concentrated in the finer size region. However, currently, the cathode active materials are being concentrated at a cut point that is considerably greater than the actual size found in spent batteries. Effective physical methods reduce the cost of subsequent chemical treatment and thereafter re-lithiation successfully reintroduces lithium into spent cathodes. Some of the current challenges are the difficulty in controlling impurities in recovered products and ensuring that the entire recycling process is more sustainable.

Recycling spent LiNi1-x-yMnxCoyO2 cathodes to bifunctional NiMnCo catalysts for zinc-air batteries

SignificanceIn recent years, lithium-ion batteries (LIBs) have been widely applied in electric vehicles as energy storage devices. However, it is a great challenge to deal with the large number of spent LIBs. In this work, we employ a rapid thermal radiation method to convert the spent LIBs into highly efficient bifunctional NiMnCo-activated carbon (NiMnCo-AC) catalysts for zinc-air batteries (ZABs). The obtained NiMnCo-AC catalyst shows excellent electrochemical performance in ZABs due to the unique core-shell structure, with face-centered cubic Ni in the core and spinel NiMnCoO₄ in the shell. This work provides an economical and environment-friendly approach to recycling the spent LIBs and converting them into novel energy storage devices.

Recycling of valuable metals from spent cathode material by organic pyrolysis combined with in-situ thermal reduction

From the perspective of environmental protection and resource recovery, recycling of spent lithium-ion batteries is a meaningful process. In this study, the removal of organics, liberatioin of electrode material, and reduction of high valence transition metal, as the key points in recycling efficiency of valuable metals, have been firstly achieved simultaneously by low temperature heat treatment recycling process. Pyrolysis characteristics of organics, phase transition behavior of spent cathode material and the thermal reduction mechanism were evaluated in the meantime. Results demonstrate that organics can be removed and the liberation of electrode materials can be improved by pyrolysis. High-valence transition metals in cathode materials are synchronously reduced to CoO, NiO, MnO, Ni, and Co based on the reducing action of organics, aluminum foil and conductive additives. At the same time, Li element exists in the form of Li₂CO₃, LiF and aluminum-lithium compound that can be recycled by water-leaching in the water impact crushing process while transition metals can be recycled by acid leaching without reducing agents. 81.26% of Li can be recycled from water-leaching process while the comprehensive recovery rate of Ni, Co, Mn is 92.04%, 93.01%, 92.21%, respectively. This study may provide an environmentally-friendly recycling flowchart of spent lithium-ion batteries.

Recycling of cathode material from spent lithium-ion batteries: Challenges and future perspectives

The intrinsic advancement of lithium-ion batteries (LIBs) for application in electric vehicles (EVs), portable electronic devices, and energy-storage devices has led to an increase in the number of spent LIBs. Spent LIBs contain hazardous metals (such as Li, Co, Ni, and Mn), toxic and corrosive electrolytes, metal casting, and polymer binders that pose a serious threat to the environment and human health. Additionally, spent LIBs may serve as an economic source for transition metals, which could be applied to redesigning under a closed-circuit recycling process. Thus, the development of environmentally benign, low cost, and efficient processes for recycling of LIBs for a sustainable future has attracted worldwide attention. Therefore, herein, we introduce the concept of LIBs and review state-of-art technologies for metal recycling processes. Moreover, we emphasize on LIB pretreatment approaches, metal extraction, and pyrometallurgical, hydrometallurgical, and biometallurgical approaches. Direct recycling technologies combined with the profitable and sustainable cathode healing technology have significant potential for the recycling of LIBs without decomposition into substituent elements or precipitation; hence, these technologies can be industrially adopted for EV batteries. Finally, commercial technological developments, existing challenges, and suggestions are presented for the development of effective, environmentally friendly recycling technology for the future.