Artificial cathode-electrolyte interphases on nickel-rich cathode materials modified by silyl functional group

Abstract

Nickel-rich nickel-cobalt-manganese layered oxides receive significant attention as advanced cathode materials, however, they suffer from poor cycling performance at elevated temperature because of surface instability. In this study, we develop nickel-rich cathode materials modified by an artificial cathode-electrolyte interphase layer embedding silyl ether functional groups. An artificial cathode-electrolyte interphase layer-functionalized nickel-rich cathode materials are simply synthesized via a wet-coating-based thermal treatment using a dimethoxydimethylsilane as an organic precursor. The task-specific silyl ether functional groups are effective in selectively scavenging nucleophilic fluoride species, which potentially triggers the dissolution of transition metal components into the electrolyte. Microscopic analyses indicate that the artificial cathode-electrolyte interphase layer is well developed on the surface of the nickel-rich cathode materials with several nanometers-thickness. The cells cycled with functionalized nickel-rich cathodes exhibit much higher cycling retentions (similar to 70.0%) than the cell cycled with bare nickel-rich cathode (47.1%) at high temperature. Additional systematical analyses indicate that the artificial cathode-electrolyte interphase layers effectively mitigate the electrolyte decomposition and the dissolution of transition metal components, thereby improving the cycling behavior of the cell on the basis of increased interfacial stability of nickel-rich cathode materials. [GRAPHICS]