Improved Cyclability of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_2 Coated with Al_2O_3 through Atomic Layer Deposition

摘要

Atomic layer deposition (ALD) for surface coating was applied to improve the stability of NCM811 at higher voltages. The Al_2O_3 coating is done in a uniform and conformal way on prefabricated electrodes using atomic layer deposition that significantly prevented surface degradation over prolonged cycling. First cycle capacity of 190, 199, 188 and 166 mAh g~(-1) is obtained for pristine, 2, 5 and 10 cycles of ALD coated samples at 0.2C and maintains 145, 158, 151 and 130 mAh g~(-1) for high current rate of 2C in room temperature. The optimized Al_2O_3 modified cathode retained 75% of its capacity after 500 cycles at 5C with 0.05% capacity decay per cycle, compared with 46.5% retention for a pristine electrode, at an elevated temperature. Despite the insulating nature of Al_2O_3 coating, a nanometer (nm) coating layer is sufficient to improve the elevated temperature performance. The protective nature of Al_2O_3 coating in preventing the detrimental surface reactions at high temperature is understood from the morphology changes between the pristine and cycled electrodes.