Enhanced Electrochemical Performance of LiNi_0.8Co_0.1Mn_0.1O₂ with SiO₂ Surface Coating Via Homogeneous Precipitation

Ni-rich LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) has been considered as a promising cathode material for high energy density lithium-ion batteries. However, it experiences undesirable interfacial side-reactions with the electrolyte, which lead to a rapid capacity decay. In this work, a homogeneous precipitation method is proposed for forming a uniform silicon dioxide (SiO₂) coating on the NCM811 surface. The strong Si−O network provided a stable protective layer between the NCM811 active material and electrolyte to improve the electrochemical stability. As a result, the NCM811@SiO₂ cathode showed superior cycling stability (84.9 % after 100 cycles at 0.2 C) and rate capability (142.7 mA h g⁻¹ at 5 C) compared to the pristine NCM811 cathode (56.6 % after 100 cycles, 127.9 mA h g⁻¹ at 5 C). Moreover, the SiO₂ coating effectively suppressed voltage decay and pulverization of the NCM811 particles during long term cycling. This uniform coating technique offers a viable approach for stabilizing Ni-rich cathode materials for high-energy density lithium-ion batteries.