Modification of Li3PO4 layer effectively boosting lithium storage and thermal safety performance for LiCoO2 batteries

Abstract

To meet the demand for high-performance LiCoO2 batteries, it is necessary to overcome challenges such as interface degradation and rapid capacity degradation caused by changes in bulk structure, especially under deep delithiation and high temperature conditions. The ion conductive coating layer of Li3PO4 has been directly modified on the surface of LiCoO2 particles using magnetron sputtering method, significantly improving the lithium storage performance of LiCoO2@Li3PO4 composites. Compared to pure LiCoO2, the modified LiCoO2 sample exhibits obviously better cycle life and high-temperature performance. Especially, under the conditions of 2 and 1 C, the LiCoO2@Li3PO4 electrode delivers excellent cycling performance at high voltage of 4.5 V, with capacity retention rates of 89.7% and 75.7% at room temperature and high temperature of 45 °C, being far greater than those of 12.3% and 29.1% for bare LiCoO2 electrodes. It is discovered that the Li3PO4 coating layer not only effectively enhances interface compatibility and suppresses the irreversible phase transition of LiCoO2, but also further improves the Li+ transport kinetics and significantly reduces battery polarization, ultimately enabling the modified LiCoO2 electrode to exhibit excellent lithium storage performance and thermal safety characteristics under high voltage conditions. Thus, such effective modified strategy can undoubtedly provide an important academic inspiration for LiCoO2 implication.