Olivine-based nano-filling layer empowering Ni-rich layered cathodes with enhanced surface stability and thermal shock resistance

Abstract

Irreversible phase transition and nerve-racking thermal runaway of NCM811 especially cycled at high charge cut-off potential hinder its full-scale commercialization. In this study, we use a facile and powerful surface modification strategy to construct modified NCM811 whose ravines are completely filled/embedded by sand-milled LiMn_0.6Fe_0.4PO₄ (LMFP), forming the nano-filled NCM811 (LMFP@NCM811). By virtue of this compact & uniform LMFP layer, a thin and stable cathode-electrolyte interface (CEI) layer can be established on the surface of LMFP@NCM811, which leads to prominent electrochemical properties with a high capacity retention of ∼ 80% after 450 cycles at 100 mAh/g. Moreover, due to the intrinsic stability of olivine structure (LMFP), the LMFP-embedded NCM811 showcases admirable thermal stability and thermal shock resistance at high de-lithiation state. We believe that such success at the performance improvement of Ni-rich ternary cathodes can provide a good guidance for future work to achieve more efficient energy storage and utilization.