Enabling Superior Electrochemical Performance of Lithium-Rich Li1.2Ni0.2Mn0.6O2 Cathode Materials by Surface Integration

Lithium-rich cathode oxides exhibit extraordinary specific capacities that are mainly ascribed to the accumulated redox reactions of anions and cations at high operating potentials. However, rapid capacity fading and voltage decay have been impeding the commercialization process. Herein, we report a surface integration strategy to improve the capacity and voltage stability of a Co-free lithium- and manganese-rich (LMR) cathode oxide Li1.2Ni0.2Mn0.6O2, by which the spinel phase and surface cobalt gradient doping are synchronously built on the surface of LMR microspheres. The spinel phase and surface cobalt gradient doping surface integration inhibit irreversible phase transformation (layered to spinel or rock-salt structure), promote lithium-ion diffusion, and improve the LMR cathode surface stability. This surface integration design enables a striking reversible discharge capacity of 280.05 mA h g–1 at 0.1 C and a superior cycling performance with a retention of 94.56% at 0.5 C after 200 cycles. Besides, the modified LMR cathode still exhibits an excellent specific capacity of 127.06 mA h g–1 at 10 C. This surface integration strategy opens a new scope for lithium-ion batteries with high energy density for practical applications in the near future.