Modulating surface reconstruction of LiNi _0.8Co _0.1Mn _0.1O ₂ via simply blending the nano-sized LiCoO ₂ particles in electrode

NCM811 is a high-capacity and widely used nickel-rich cathode material for lithium-ion batteries, but its fragile surface structure severely limits the cycle stability. In this work, by blending the nano-sized LiCoO₂ (nano-LCO) particles in NCM811 electrode, the surface structure reconstruction of NCM811 upon cycle is successfully achieved. Due to the short Li⁺ diffusion path  within the nano-LCO particles, Li⁺ diffusion kinetics is significantly enhanced. Thus, when these nano-particles are blended in the NCM811 electrode, the Li⁺extraction across the surface of NCM811 particles can be homogenized, which further promotes the uniformity of “layered/rocksalt (RS)” phase transitions in the surface region. This homogenization of surface state of charge (SOC) inhibits the rapid formation and thickening of the high-impedance RS phase, thereby enhancing the cycle and rate performances of NCM811-based electrode. This study deepens the understanding of the performance optimization mechanisms at the electrode level for NCM811-based electrodes.