H3BO3 washed LiNi0.8Co0.1Mn0.1O2 with enhanced electrochemical performance and storage characteristics

Abstract LiNi0.8Co0.1Mn0.1O2 (NCM811) is a very promising Ni-rich layered cathode material for Li-ion batteries due to its low cost and high discharge capacity. However, the residual lithium deteriorates its electrochemical and storage performances, which hinders its application. Here, we propose a novel facial surface modification strategy, using H3BO3 to clean the surface of NCM811, and then convert the residual lithium into a uniform lithium-boron compound layer through subsequent calcination, thereby improving lithium ion diffusion and electron transport. The sample washed with H3BO3 displays a smooth surface that covered by lithium-boron compounds and shows a much lower content of residual lithium compared with pristine NCM811 and ethanol washed sample. The electrochemical results indicate that the H3BO3 washed material exhibits a higher discharge capacity (196.9 mAh g−1 at 0.1C) and a better capacity retention at 0.5C (96.49% after 100 cycles). With a layer of lithium-boron compounds, the NCM811 becomes more resistant to corrosion by the electrolyte, which results in a stable surface crystal structure. In addition, the H3BO3 washed NCM811 does not have obvious growth of residual lithium in the ambient, which shows better storage performance and is of great significance for practical application.