Vapor-assisted synthesis of Al2O3-coated LiCoO2 for high-voltage lithium ion batteries
A simple and facile vapor-assisted hydrolysis route has been used to synthesize Al2O3-coated LiCoO2. The effects of Al2O3 coating on the structure and electrochemical performance have been systematically studied. After deposition of the Al2O3 coating, the crystal structure and morphology of LiCoO2 are maintained. Galvanostatic charge-discharge tests show that Al2O3-coated LiCoO2 exhibits markedly improved capacity retention and rate capability at high charge voltage (4.5 V). The Al2O3-coated LiCoO2 exhibits an initial discharge capacity of 165.5 mAh/g at 360 mA/g, and the capacity retention is 98.6% after 180 cycles. The electrochemical impedance spectroscopy results demonstrate that the Al2O3 coating can slow the increase of charge-transfer resistance during cycling, which is in accord with the excellent electrochemical cycling performance of Al2O3-coated LiCoO2.