Unveiling thermal decomposition kinetics of Single-Crystalline Ni-Rich LiNi0.88Co0.07Mn0.05O2 cathode for safe Lithium-Ion batteries

Insufficient thermal stabilities of LiN(ix)CoyMn(1-x-y)O(2) (NCM) families have aroused wide concerns and safety threats against large-scale application due to oxygen releasing and exothermic side reactions. Towards energy dense batteries, single-crystalline NCM has been recently highlighted as a promising substitution in providing improved capacity retention beyond polycrystalline counterparts. However, their thermal-driven degradation mechanism remains under investigation and yet critically essential. In this contribution, we have rationally explored the thermal-driven fading behavior of delithiated single-crystalline and polycrystalline LiNi0.88-Co0.07Mn0.05O2. Followed by the Avrami-Erofeev mechanism, a three-step decomposition procedure has been deconvoluted from time-resolved X-ray diffraction and physicochemical analysis, in terms of solid electrolyte interface (SEI) decomposition, layered-to-spinel transition and spinel-to-rock-salt transition. According to thermal kinetic analysis, polycrystalline LiNi0.88Co0.07Mn0.05O2 exhibits higher decomposition temperature and lower decomposition rate than that in single-crystalline counterparts, contributing to better thermal stability. This study has provided a fundamental understanding of the thermal decomposition of Ni-rich LiNi0.88-Co0.07Mn0.05O2 cathodes and insights of NCM families protection.