Ever-growing global energy needs and environmental damage have motivated the pursuit of sustainable energy sources and storage technologies. As attractive energy storage technologies to integrate renewable resources and electric transportation, rechargeable batteries, including lead-acid, nickel-metal hydride, nickel-cadmium, and lithium-ion batteries, are undergoing unprecedented rapid development. However, the intrinsic toxicity of rechargeable batteries arising from their use of toxic materials is potentially environmentally hazardous. Additionally, the massive production of batteries consumes numerous resources, some of which are scarce. It is therefore essential to consider battery recycling when developing battery systems. Here, we provide a systematic overview of rechargeable battery recycling from a sustainable perspective. We present state-of-the-art fundamental research and industrial technologies related to battery recycling, with a special focus on lithium-ion battery recycling. We introduce the concept of sustainability through a discussion of the life-cycle assessment of battery recycling. Considering the forecasted trend of a massive number of retired power batteries from the forecasted surge in electric vehicles, their repurposing and reuse are considered from economic, technical, environmental, and market perspectives. New opportunities, challenges, and future prospects for battery recycling are then summarized. A reinterpreted 3R strategy entailing redesign, reuse, and recycling is recommended for the future development of battery recycling.

An environmentally friendly leaching process for recycling valuable metals from spent lithium-ion batteries is developed. A sol–gel method is utilized to resynthesize LiNi1/3Co1/3Mn1/3O2 from the leachate. Lactic acid is chosen as a leaching and chelating agent. The leaching efficiency is investigated by determining the contents of metal elements such as Li, Ni, Co, and Mn in the leachate using inductively coupled plasma optical emission spectroscopy. The spent cathode materials for the pretreatment process and the regenerated and freshly synthesized materials are examined using X-ray diffraction and scanning electronic microscopy. The results show that the leaching efficiencies of Li, Ni, Co, and Mn reached 97.7, 98.2, 98.9, and 98.4%, respectively. The optimum conditions are lactic acid concentration of 1.5 mol L–1, solid/liquid ratio of 20 g L–1, leaching temperature of 70 °C, H2O2 content of 0.5 vol %, and reaction time of 20 min. The leaching kinetics of cathode scrap in lactic acid fit well to the Avrami equation. Electrochemical analysis indicate that the regenerated LiNi1/3Co1/3Mn1/3O2 cathode materials deliver a highly reversible discharge capacity, 138.2 mA h g–1, at 0.5 C after 100 cycles, with a capacity retention of 96%, comparable to those of freshly synthesized LiNi1/3Co1/3Mn1/3O2 cathodes.

The burst demand of lithium-ion batteries (LIBs) for energy storage leads to an increasing production of LIBs. The huge amount of electrode scraps produced during the industrial production cannot be overlooked. A sustainable and simple method was developed to regenerate Li­(Ni1/3Co1/3Mn1/3)­O2 electrode scraps as new cathodes for LIBs. Three different separation processes, including direct calcination, solvent dissolution, and basic solution dissolution, were applied to obtain the active materials. Then, a heat treatment was used to regenerate the scraps. The effects of separation methods and heat treatment temperatures were systematically investigated. The results show that the scraps regenerated with solvent dissolution and heat treatment at 800 °C deliver the highest reversible discharge capacities of 150.2 mA h g–1 at 0.2C after 100 cycles with capacity retention of 95.1%, which is comparable with commercial Li­(Ni1/3Co1/3Mn1/3)­O2 cathodes. When cycled at 1C, a highly reversible discharge capacity of 128.1 mA h g–1 can be obtained after 200 cycles. By contrast, scraps regenerated through a direct calcination method at 600 °C exhibit the best cycling performances, with the highest capacity retention of 96.7% after 100 cycles at 0.2C and 90.5% after 200 cycles at 1C. By characterizations of XRD, SEM, XPS, and particle size distribution analysis, the improved electrochemical performances of regenerated cathodes can be attributed to the uniform particle morphology and newly formed protective LiF composite. The simple and green regeneration process provides a novel perspective of recycling scraps from industrial production of LIBs.

Rapid development of energy storage system causes a burst demand of lithium-ion batteries (LIBs), and large number of spent LIBs with high valuable metals are produced. Here we propose a novel application of oxalic acid leaching to regenerate Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 (NCM) cathodes from spent LIBs. With lithium dissolving into the solution, the transition metals transform into oxalate precipitates and deposit on the surface of spent NCM cathodes, separating lithium and transition metals in one simple step. After mixing with certain amount of Li 2 CO 3 , the oxalate precipitates together with unreacted NCM are directly calcined into new NCM cathodes. The regenerated NCM after 10 min leaching exhibits the best electrochemical performances, delivering the highest initial specific discharge capacity of 168 mA h g −1 at 0.2C and 153.7 mA h g −1 after 150 cycles with a high capacity retention of 91.5%. The excellent electrochemical performances are attributed to the submicrometer particles and voids after calcination, as well as the optimal proportion of elements. This process can make the most of valuable metals in the spent cathodes, with >98.5% Ni, Co, and Mn recycled. It is simple and effective, and provides a novel perspective of recycling cathodes from spent LIBs.

Recycling of spent LiFePO 4 batteries has drawn recent attention relating to recovering their high contents of rare elements and negating potential negative environmental effects of their disposal. However, the stable crystal structure of LiFePO 4 materials has prevented the development of a recycling process with high selectivity and extraction efficiency. We report the selective extraction of Fe and Li from spent LiFePO 4 batteries via an environmentally friendly mechanochemical process with oxalic acid. With the use of a mechanochemical treatment and water leaching, the Li extraction efficiency can be improved to 99%. Furthermore, 94% of Fe can be simultaneously recovered as FeC 2 O 4 •2H 2 O. To understand the reaction mechanism and determine the optimum reaction conditions, we investigated various parameters, including the LiFePO 4 to oxalic acid mass ratio, rotation speed, milling time, and ball-to-powder mass ratio. Moreover, metal ions from the water leaching process were recovered by chemical precipitation. This study provides an efficient and selective process for recovery of valuable metals from spent LiFePO 4 materials.