Layered-Spinel Heterogeneous Structure and Oxygen Vacancies Enable Superior Electrochemical Performance for Li-Rich Cathodes.

Lithium-rich manganese-based oxides (LRMOs) materials are considered to be the next-generation cathode for high-energy lithium-ion/metal batteries owing to their superior specific capacity, high operation voltage, and low cost. However, the commercial application of LRMOs is constrained by the surface structure degradation and lattice oxygen release, resulting in low initial coulombic efficiency (ICE) and rapid voltage and capacity decay. Herein, we propose a facile sorbic acid-assisted surface treatment strategy to construct homogeneous multifunctional interface layers composed of layered-spinel heterogeneous structure and oxygen vacancies on the surface of LRMOs, which enhance the structure stability and improve the activity and reversibility of the anionic oxygen redox reactions. The multifunctional interfacial layers effectively suppress irreversible oxygen release and alleviate unfavorable layered-spinel phase transformation. As a consequence, the treated LRMOs cathode displays improved ICE of 88.3%, high capacity retention rate (87.9% at 1 C after 150 cycles) and low voltage decay ratio (1.26 mV per cycle). These findings provide a valuable new idea to improve the comprehensive electrochemical performance of LRMOs through multi-strategy synergistic interface engineering techniques.