Sustainable recovery of LiCoO2 from spent lithium-ion batteries: Simplicity, scalability, and superior electrochemical performance

•Utilization of external circuit discharge to fully discharge and safely disassemble.•Re-lithiation with a trace lithium source can restore the bulk crystal structure.•LNMO coating and re-lithiation can be achieved in one heat treatment step.•High voltage LNMO-SLCO exhibits better cycle and rate performance.•This short process regeneration strategy is low-cost and can be scalable. In light of the ecological ramifications and material consumption stemming from exhausted lithium-ion batteries, an exigent requirement persists for efficient and expansible recycling techniques. Herein, we investigate an innovative expedited method to directly regenerate and enhance spent LiCoO2 (SLCO). The profoundly discharged SLCO powders, featuring an unimpaired crystal lattice, are isolated. These powders are then amalgamated with Li, Ni, and Mn precursors. Subsequent heating at elevated temperatures yields LNMO-SLCO, effecting the direct regeneration of LCO, accompanied by a synergistic re-lithiation process and the application of a LiNi0.5Mn1.5O4 (LNMO) coating, all achieved in a single step. The homogeneously thin spinel LNMO coating layer (10–15 nm) bestows upon LNMO-SLCO an enhanced cycling performance and charge–discharge rate capacity when benchmarked against SLCO and commercial LiCoO2 (CLCO). Evidently, at 0.1C, 0.5C, and 2C rates, LNMO-SLCO delivers discharge capacities of 214.4 mAh g−1, 187.4 mAh g−1, and 144.1 mAh g−1, respectively. Notably, it sustains 77.68 % of its original capacity following 100 cycles at 0.5 C. The merits of LNMO-SLCO are corroborated through cyclic voltammetry and electrochemical impedance spectroscopy, affirming its reduced charge transfer resistance and augmented lithium-ion solid phase diffusion coefficient. This endeavor stands as the foremost documented instance of a direct approach to SLCO reconstruction involving LNMO coating, culminating in the formation of LNMO-SLCO, characterized by sustained high-voltage cycling performance. The outlined re-lithiation and LNMO coating stratagem proffer valuable insights for the scalable, high-value recycling of SLCO, while remaining transposable to other spent cathode materials.