Multifunctional Integration of Double-Shell Hybrid Nanostructure for Alleviating Surface Degradation of LiNiCoMnO Cathode for Advanced Lithium-Ion Batteries at High Cutoff Voltage.

Ni-rich LiNiCoMnO (NCM811) cathode is considered to be among the most promising candidates for high-energy-density lithium-ion batteries (LIBs). However, both capacity fading and structural degradation occur during long-term cycling, which extremely limit the commercial applications of NCM811, especially at a high cutoff voltage (>4.3 V). Here, we design a double-shell hybrid nanostructure consisting of a LiSiO coating layer and a cation-mixed layer (3̅ phase) to improve its electrochemical performance. Consequently, the Si-modified NCM811 electrode shows outstanding cycling stability with a 95.2% capacity retention at 4.3 V after 100 cycles and 87.3% at a 4.5 V high cutoff voltage after 100 cycles. This designed double-shell hybrid nanostructure alleviates side reactions, structural degradation, and internal cracking, effectively enhancing the surface structural stability. This efficient strategy provides a valuable step toward further commercial applications of the LiNiCoMnO cathode and enriches the fundamental understanding of layered cathode materials.