Synergistic strategy of surface-induced spinel structure and F doping to improve the electrochemical performance of Li-rich cathodes

Abstract

Li-rich Mn-based materials provide higher capacity than commercial NCM layered materials due to the synergistic redox effect of cations and anions. However, lattice straining and structural collapse caused by the irreversible oxygen release at high voltage range during cycling, which results in severe capacity and voltage decay. Herein, a synergistic strategy of surface-induced spinel structure and F doping is provided to improve the structural stability. The surface spinel structure helps to reduce the structural collapse caused by electrolyte corrosion on the cathode and effectively inhibits voltage decay resulted from structural evolution. The stronger Mn-F bonds are formed by F doping to inhibit migration of transition metal (TM) and induce the uniform deposition of LiF to form the thinner and more stable CEI on the cathode. Accordingly, the designed cathode (LMNO-NF) shows remarkable cycling performance with the capacity retention of 86.68 ​% and voltage retention of 96.6 ​% for 200 cycles at 1C, higher than pristine material (68.76 ​% and 85.75 ​%). Therefore, this simple dual-modification strategy of one-step synthesis is promising for solving the structural evolution and voltage decay of Li-rich Mn-based cathode materials effectively, achieving further commercialization.