A Li-rich layered-spinel cathode material for high capacity and high rate lithium-ion batteries fabricated via a gas-solid reaction

Lithium-rich layered oxide (LLO) cathode materials have drawn extensive attention due to their ultrahigh specific capacity and energy density. However, their commercialization is still restricted by their low initial coulombic efficiency, slow intrinsic kinetics and structural instability. Herein, a facile surface treatment strategy via gaseous phosphine was designed to improve the rate performance and capacity stability of LLOs. During the solid-gas reaction, phosphine reacted with active oxygen at the surface of LLOs due to its reductivity, forming oxygen vacancies and spinel phase at the surface region. As a result, Li ion conductivity and structural stability were greatly enhanced. The phosphinetreated LLOs (LLO@P) showed a layered-spinel hybrid structure and delivered an outstanding rate performance of 156.7 mA h g−1 at 10 C and a high capacity retention of 74% after 300 cycles at 5 C.