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A new process is optimized and presented for the recovery and regeneration of LiFePO4 from spent lithium-ion batteries (LIBs).

As an indispensable part of lithium-ion batteries (LIBs), closed-loop recycling, reusing the electrolyte from spent LIBs, has not yet been fulfilled experimentally. Herein, this paper presents a LIB electrolyte recycling approach which consists of supercritical CO2 extraction, resin, and molecular sieve purification and components supplements. The resultant electrolyte exhibited a high ionic conductivity of 0.19 mS·cm–1 at 20 °C, which was very close to a commercial electrolyte with the same composition. Moreover, the electrolyte was also electrochemically stable up to 5.4 V (vs Li/Li+) in the linear sweep voltammetry (LSV) measurement. The application potential of reclaimed electrolyte was demonstrated by Li/LiCoO2 battery presenting the initial discharge capacity of 115 mAh·g–1 with a capacity retention of 66% after 100 cycles at 0.2 C. This investigation is a crucial break for electrolyte recycling and opens a bright route toward realizing closed-loop LIB recycling.

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Stabilizing Li‐rich layered oxides without capacity/voltage fade upon cycling is a prerequisite for a successful commercialization. Although the inhibition of structural and interfacial changes is identified as an effective strategy, the battery community always seeks for a technologically flexible method to make it really competitive among the cathode. Herein, the gradient W‐doping within Li1.2Mn0.56Ni0.16Co0.08O2 (LLMO) is proposed to relieve crystal disintegration and simultaneously enhance interfacial stability because of the formation of Li2WO4 coating layer on the material surface. This is mainly attributed to the scenario that partial Mn replacement by W can stabilize the LLMO structure and regulate the electrochemical activity of Mn element. The W‐doped LLMO (W@LLMO) possesses improved specific capacity and voltage stability (83.2% capacity retention and voltage retention of 94.9% after 200 cycles at 0.5 C). Besides, a practical pouch cell based on the W@LLMO cathode presents sufficient gravimetric energy density (318 Wh kg−1) and cycling stability (capacity retention of 87.7% after 500 cycles at 1.0 C). This study presents an effective method to design robust Li‐rich layered cathodes for next‐generation Li‐ion batteries.