Recycling of protective layer of Ni rich layered oxide material in Li ion batteries

Abstract

We investigated the recycling of protective layer of Ni rich layered oxide–material used in Li ion batteries. Decreasing electrochemical performance of the cathode powder while leaving the powder in air was confirmed by various analyses and was found to be due to the formation of lithium residuals. The surface of the protective layer of Ni rich layered oxide was covered by the lithium residuals and that led to the cancellation of the coating effect. The residual lithium decreased and the cell performance was recovered by following a recycling process in this work. After the recycling process, the performance of the protective layer became similar to that of the layer immediately after the initial coating, and the coating layer showed a resurgence, which was confirmed by SEM and TEM images. The capacity of the initial coated Ni rich NCM and the sample after recycling was 209 and 206 mAh/g at 1C, respectively. The cycle retention for the initial coated Ni rich NCM and the sample after recycling was 93.4 and 92.6 % after 50 cycles at 1C, respectively. It is concluded that the coating layer and the electrochemical performance were recovered by the recycling process.