Improved Cyclability of LiNi0.8Co0.1Mn0.1O2 Coated with Al2O3 through Atomic Layer Deposition

Atomic layer deposition(ALD) for surface coating was applied to improve the stability of NCM811 at higher voltages. The Al2O3 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 Al2O3 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 Al2O3 coating, a nanometer (nm) coating layer is sufficient to improve the elevated temperature performance. The protective nature of Al2O3 coating in preventing the detrimental surface reactions at high temperature is understood from the morphology changes between the pristine and cycled electrodes.