Boosting rate performance of LiNi0.8Co0.15Al0.05O2 cathode by simply mixing lithium iron phosphate

Abstract

LiNi0.8Co0.15Al0.05O2 (NCA), a cathode material for lithium-ion batteries (LIBs), is a promising material due to its high specific capacity. However, there are drawbacks like high cost, safety issues, and limited cycle-performance that represent obstacles for commercial applications. This study describes a simple ballmilling method to modify the surface of NCA materials and fill the gaps between particles by LiFePO4 (LFP) cathode to improve its charge/discharge rate. The results show that NCA@5LFP, mixed with 5 wt % LFP, has the best cycling and rate performance, with a higher capacity-retention (89.4% after 200 cycles, at 2C). Post-electrochemical and in-situ analysis reveal more detailed reasons of the observed improvements. The formation of a more stable solid electrolyte interface film in the NCA@5LFP hybrid electrode helps ensure the orderliness of the NCA structure, by reducing the charge-transfer resistance, and increasing the channel for lithium ion de-intercalation. All these factors help improve the battery performance.