Enhanced Cycling Stability of 4.6 V LiCoO₂ Cathodes by Inhibiting Catalytic Activity of its Interface Via MXene Modification

Abstract

Abstract LiCoO 2 plays a key role in energy storage devices due to its high energy density. And the volumetric energy density of LiCoO 2 cathode can be significantly improved by increasing the charging cut‐off voltage to 4.6 V. However, the increase in resistance at the LiCoO 2 interface, and the damage to the LiCoO 2 from the outside to the inside by the HF generated that caused by the decomposition of the organic electrolyte and LiPF 6 under 4.6 V conditions are not conducive to structural stability during cycling. Here, it is shown that the decomposition of electrolyte and LiPF 6 is effectively mitigated by inhibiting the interfacial catalytic activity of LiCoO 2 using an atomically thin layer of MXenes as a interlayer. Density functional theory results suggest that the decomposition energy of LiPF 6 is 1.13 and 3.21 eV at the interface of LiCoO 2 and MXenes, respectively. Time of Flight Secondary Ion Mass Spectrometry results further indicate that the decomposition products of the organic electrolyte and LiPF 6 have a thinner thickness at the interface of MXenes (5 nm) than LiCoO 2 (10 nm). This study provides a new and universal strategy for stabilizing the cathode interface to support the development of high energy density lithium‐ion batteries.