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

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 LiCO 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 LiNiCoAlO (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.