Promotion of Li+ desolvation and efficient cathode interphase formation by 4-aminobenzoic multifunctional electrolyte additive

Abstract

The application of Li metal anode in high energy density batteries is hindered by uncontrolled dendrites growth and rapid capacity decline. In this study, 4-aminobenzoic acid (4-ABA) is used as a multifunctional electrolyte additive to effectively stabilise Li anode and extend the cycling life of LiNi0.8Co0.15Al0.05O2 (NCA) cathode in carbonate electrolyte. It is found that 4-ABA facilitates the desolvation of Li+ and increases the Li+ transference number, leading to an increase in Li+ flux on the surface of the Li anode, and finally the growth of Li dendrites is inhibited. The cycling performance of Li||Li symmetric cell is extended from < 400 h to more than 600 h at 1 mA cm−2 with a capacity of 1 mAh cm−2. For the NCA cathode, 4-ABA is involved in the formation of a thin and uniform cathode electrolyte interphase (CEI) layer, which is conducive to inhibiting the corrosion of electrolyte on NCA cathode and reducing the dissolution of the transition metals Ni and Co. Thus, the electrochemical performances of the Li||NCA cell with the electrolyte containing 0.5% 4-ABA are significantly improved. In particular, the discharge capacity of the cells with the electrolyte containing 0.5% 4-ABA are still 164.9 and 150.7 mAh g−1compared to only 126.3 and 116.0 mAh/g for the cells with the baseline electrolyte after 200 cycles at 1C and 5C. This study provides a simple and effective strategy for improving the electrochemical performances of Li anodes and NCA cathodes by optimising the electrolyte.