Enhanced Surface Chemical and Structural Stability of Ni-Rich Cathode Materials by Synchronous Lithium-Ion Conductor Coating for Lithium-Ion Batteries

Abstract

Ni-rich cathode materials LiNi<i>_x</i>Co<i>_y</i>Mn_{1-<i>x</i>-<i>y</i>}O₂ (<i>x</i> ≥ 0.6) have attracted much attention due to their high capacity and low cost. However, they usually suffer from rapid capacity decay and short cycle life due to their surface/interface instability, accompanied by the high Ni content. In this work, with the Ni_0.9Co_0.05Mn_0.05(OH)₂ precursor serving as a coating target, a Li-ion conductor Li₂SiO₃ layer was uniformly coated on Ni-rich cathode material LiNi_0.9Co_0.05Mn_0.05O₂ by a precoating and syn-lithiation method. The uniform Li₂SiO₃ coating layer not only improves the Li-ion diffusion kinetics of the electrode but also reduces mechanical microstrain and stabilizes the surface chemistry and structure with a strong Si-O covalent bond. These results will provide further in-depth understanding on the surface chemistry and structure stabilization mechanisms of Ni-rich cathode materials and help to develop high-capacity cathode materials for next-generation high-energy-density Li-ion batteries.