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

Abstract

AbstractLiCoO2 plays a key role in energy storage devices due to its high energy density. And the volumetric energy density of LiCoO2 cathode can be significantly improved by increasing the charging cut‐off voltage to 4.6 V. However, the increase in resistance at the LiCoO2 interface, and the damage to the LiCoO2 from the outside to the inside by the HF generated that caused by the decomposition of the organic electrolyte and LiPF6 under 4.6 V conditions are not conducive to structural stability during cycling. Here, it is shown that the decomposition of electrolyte and LiPF6 is effectively mitigated by inhibiting the interfacial catalytic activity of LiCoO2 using an atomically thin layer of MXenes as a interlayer. Density functional theory results suggest that the decomposition energy of LiPF6 is 1.13 and 3.21 eV at the interface of LiCoO2 and MXenes, respectively. Time of Flight Secondary Ion Mass Spectrometry results further indicate that the decomposition products of the organic electrolyte and LiPF6 have a thinner thickness at the interface of MXenes (5 nm) than LiCoO2 (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.