Construction of core-shell Li3PO4@LiNi0·5Co0·2Mn0·3O2 cathode with improved cycling stability for lithium ion batteries

Abstract

Residual Li on surface of spherical particles of LiNi0·5Co0·2Mn0·3O2 (NCM523) was used to synthesise the core-shell structure of Li3PO4 @ NCM523 for enhancing structural stability and long-cycle life. The optimal mass ratio (Li3PO4:NCM523) was found to be 0.5 wt% (LPO-0.5), and the thickness of Li3PO4 on the surface of LPO-0.5 was approximately 12 nm. Compared with the pristine NCM523, the Li3PO4 @ NCM523 cathode material not only has a longer cycle life, but also exhibits better structural stability. The Li3PO4 layer inhibits the electrolyte from eroding the NCM523 cathode material and prevents the volume loss of the active microsphere during cycling. Furthermore, the core-shell structure of material observed via scanning electron microscopy was well maintained after 200 cycles. These results verify that the core-shell structure of material contributes to the improvement of Ni-based cathode structural stability and that the simple process favours the industrial application.