Enhanced high-temperature performance and thermal stability of lithium-rich cathode via combining full concentration gradient design with surface spinel modification

Abstract

Abstract Lithium-rich layered oxides (LLOs) are considered as the most promising candidate for the cathode of high energy density lithium-ion batteries. However, the poor cycle stability especially under high temperature is hindering its practical applications. Herein, a full concentration gradient LLO with spinel modification is designed and prepared. This synergistic strategy not only makes full use of high Ni content that improving the discharge voltage but also mitigates the detrimental influence of surface residual alkalis. The surface spinel modified cathode exhibits a higher initial coulombic efficiency of 87.52% with enhanced cycle stability at 55 °C (191.5mAh/g after 200 cycles at 1C), the average discharge voltage drop is also alleviated to 3.17 mV per cycle (at 55 °C). Furthermore, it also shows enhanced thermal stability, in which the exothermic onset temperature rises from 265.380 to 295.221 °C, and the thermal release decreases from 211.525 to 181.181 J/g. This work proposes an integrated strategy to enhance the comprehensive performance of LLOs, thus shed a light on the way for its practical application.