Interfacial oxygen coordination environment regulation towards high-performance Li-rich layered oxide cathode

Abstract

Lithium-rich layered oxides (LLO) have drawn increasing attention as one of the most promising cathodes for next-generation high-energy–density lithium-ion batteries (LIBs). However, they are plagued by low initial Coulombic efficiency (ICE) and terrible cyclic stability due to their intrinsic irreversible oxygen release. Herein, to enhance the comprehensive electrochemical performance of LLO, an effective strategy is brought up to regulate the interfacial oxygen coordination environment via lithium deficiencies, Na+ ion doping, as well as the induced Li+/Ni2+ antisite defects and in-situ epitaxial grown spinel phase. The density functional theory calculations (DFT) confirm that the existence of lithium deficiencies and Na+ ions doping can decrease the diffusion energy barrier of Li+ ions. Meanwhile, the regulated oxygen coordination environment results in an increase in the oxygen vacancy formation energy, which is beneficial for the improvement of the lattice oxygen stability in the deeply charged state. As a result, the modified sample exhibits high initial coulombic efficiency of 91.2% and good capacity retention of 95.3% after 400 cycles at 1C (1C = 250 mA g−1). This work offers a new idea for designing advanced LLO cathodes, which could promote their practical applications in high-energy–density LIBs.