Constructing an organic artificial cathode electrolyte interphase of multi-functions on single-crystal LiNi0.8Co0.1Mn0.1O2 cathode

Nickel-rich layered oxide materials are of great significance for high energy density lithium-ion batteries due to their high theoretical capacity. However, interfacial side reaction is known to be an important cause for their electrochemical degradation. Herein, we construct an organic artificial solid electrolyte interface with 4-cyanophenylboronic acid (4-CPBA) as a precursor on a single-crystal LiNi0.8Co0.1Mn0.1O2 (NCM811) surface. As a strong electron-absorbing group, cyano groups help to anchor the interfacial Ni2+ while the boronic acid groups contributes to remove the residual lithium and passivate the NCM811 surface. After wrapping the 11 nm thick artificial cathode electrolyte interface (CEI) precursor, the prepared NCM811 cathode exhibits an improved first coulomb efficiency of 93.5% at high temperature. A capacity retention of 82.5% after 200 cycles is obtained at 1C charge-discharge condition, significantly higher than that of 61.0% for the pristine cathode. The post analysis reveals that 4-CPBA is involved in the formation of CEI film and of many different functions on the cathode surface. The new interfacial modification strategy based on the synergistic interaction between the high nickel cathode material and functional organic molecules expands CEI technologies on nickel rich cathode materials.