Inverse Spinel-Structured Mg₂MnO₄ Coating to Enable Superior Thermal Stability of LiNi_0.83Co_0.12Mn_0.05O₂ Cathodes for Lithium-Ion Batteries

Abstract

Ni-richlayered oxides are commonly used as cathode materials in lithium-ion batteries due to their high energy density. However, these materials suffer from rapid capacity decay and inferior thermal stability during charging and discharging, caused by intergranular cracks, undesirable side reactions, and irreversible rock salt phase formation. Herein, we propose a facile surface engineering modification strategy using a Mg2MnO4 (MMO) coating to improve the cycling performance and thermal stability of Ni-rich cathode materials. Owing to the high structural stability of the inverse spinel structure of the MMO shell, the MMO coating acts as a physical barrier, protecting the particles from electrolyte corrosion and inhibiting intergranular cracks, thus maintaining the structural integrity of the MMO-coated Ni-rich cathode material during long-term cycling, even under harsh cycling conditions. Our electrochemical performance tests confirm that the MMO-coated Ni-rich cathode material demonstrates superior cycling and thermal stability, achieving an excellent capacity of 188.5 mA h g–1 after 200 cycles with a capacity retention of 92.7% at 50 °C. Notably, the pouch-type full cell displays outstanding performance, achieving a capacity retention of 86.2% after 400 cycles at 50 °C. Our work offers valuable insights into the development of Ni-rich cathode materials for promising applications in electric vehicles.