Li4Ti5O12-TiO2 Composite Coating Layer Enabling LiNi0.8Co0.1Mn0.1O2 Electrodes with Superior Cycling Performance

Nickel-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) materials are considered to be one of the cathode candidate materials for high energy density lithium-ion batteries (LIBs), but its electrochemical instability caused by electrodes to electrolyte interface degradation needs to be overcome. Surface coatings can effectively solve this problem. However, traditional coating techniques cover particles rather than electrodes to protect a broader area. Herein, for a more precise coating, a nanoscale Li4Ti5O12-TiO2 composite coating layer (LTOTO) is directly sputtered onto the NCM811 electrodes surface. The LTOTO has superior electronic conductivity compare to Li4Ti5O12. Lithium ions and electrons can diffuse and distribute more uniformly owing to the LTOTO coating on NCM811 electrode. For NCM811 electrodes, the LTOTO coating layer serves as the cathode-electrolyte interface (CEI) within the cycling potential range. Because of its robust structure and strong chemical inertness, LTOTO may successfully shield NCM811 electrodes from electrolyte reactions. The rate performance of NCM811 electrodes is significantly enhanced after Li4Ti5O12-TiO2 coating at 5C (149.74 mAh/g). The capacity retention of NCM811/ LTOTO-3 electrode at 1C is 93.2 % at the 100th cycle, which is 13.3 % higher than that of the pristine NCM811 electrodes.