Effective recovery of the air-exposed Ni-rich lithium transition metal oxide cathodes with a coating-stabilized surface

The electrochemical cycling performance of Ni-rich cathode materials is adversely affected by the exposure of the active materials to the ambient environment, especially for a harsh cycling condition. To mitigate this degradation, LixByC1-yOz (LBCO) was synthesized where B and C are with identical chemical bonding structures and a 0.5 at% LBCO sol-gel coating process is introduced. Here we provide a comprehensive characterization of the coating material and the effect of coating. We confirm the effectiveness of the coating method and optimize processing parameters from both chemical and electrochemical perspectives. The coating and following process can regenerate the deteriorated surface and recover the capacity. After extended cycling, we demonstrate that the LBCO coating stabilized the surface and protected the bulk from severe structural degradation, with multiscale electron microscopy and spectroscopy characterization techniques. Our in-depth investigation provides a promising approach to recovering the degraded surface structure and electrochemical performance by applying LBCO coatings.