Analyzing the mechanism of performance improvement in LiNi0.8Co0.1Mn0.1O2 through coating with LiNbO3 fast ion conductor

Abstract

The high-nickel cathode LiNi0.8Co0.1Mn0.1O2 (NCM811), a material already commercialized, faces a critical challenge in its diminished stability, leading to a decline in battery performance. This study addresses this issue by employing LiNbO3 as a fast ion conductor with varying concentrations to enhance the performance of the NCM811 material. Particularly noteworthy is the optimal performance observed with a 3% LiNbO3 coating, where the NCM811 exhibits a capacity retention of 87.10% after 200 cycles at 1 C, and a discharge capacity of 160 mAh•g−1 at a 5 C rate, surpassing the Pristine's 69.57% cycle retention and 139 mAh•g−1 at 5 C. Density Functional Theory (DFT) calculations reveal that the LiNbO3 coating not only reduces the migration barrier for Li+ within the NCM811 but also lowers the migration barrier for Li+ from the NCM811 layer to the LiNbO3 layer. Theoretical calculations further unveil that the binding energy between NCM811 and the byproduct HF in the electrolyte is lower than the binding energy between LiNbO3 surface and HF, confirming the effective inhibition of HF corrosion by the LiNbO3 layer. This work provides an in-depth analysis of the mechanism behind the improved performance of NCM811 materials through surface coating with LiNbO3.