Synthesis of high-voltage (4.7 V) LiCoO2 cathode materials with Al doping and conformal Al2O3 coating by atomic layer deposition

The electrochemical properties of high-voltage (4.7 V) LiCoO2 cathode materials with Al doping and a conformal Al2O3 coating by atomic layer deposition were studied in this paper. It was found that at <= 4.5 V, the Al2O3 ALD coating is sufficient to sustain the stability of LiCoO2, with capacities of 190 mA h g(-1) at 0.1C and 175 mA h g(-1) at 1C. However, at 4.7 V, Al doping is more effective at maintaining the cycling life than the Al2O3 coating. LiCoO2 with an Al2O3 ALD coating loses 34% of its initial capacity, but LiCoO2 with Al doping preserves 81% of its initial capacity after 110 cycles, indicating a more pronounced effect on retaining the structural stability of LiCoO2.