Air-Induced Degradation and Electrochemical Regeneration for the Performance of Layered Ni-Rich Cathodes

Abstract

Nickel-rich layered oxides are promising cathodes for power batteries owing to their high capacity and low cost. However, during the production, storage, and application of nickel-rich cathodes, especially in case the Ni content exceeds 70%, their surfaces almost inevitably react with ambient air to form electrochemically inert Li₂CO₃ and LiOH, leading to significant capacity loss and therefore imposing a significant hurdle to practical applications of nickel-rich cathodes. Here, we reveal surface structures and electrochemical properties of the exposed LiNi_0.8Co_0.15Al_0.05O₂ (NCA) cathodes and investigate systematically the impact of exposure humidity, temperature, and time on NCA cathodes. We demonstrate that introduction of a 3.0-4.5 V galvanostatic cycling operation at initial cycles can remarkably regenerate the subsequent 3.0-4.3 V battery performances of the exposed cathode. This work represents a facile method to regenerate the battery performance of surface-degraded nickel-rich cathodes, opening up an avenue in fulfilling efficient production, storage, and application of nickel-rich cathode materials.