Benzoic Anhydride as a Bifunctional Electrolyte Additive for Hydrogen Fluoride Capture and Robust Film Construction over High‐Voltage Li‐Ion Batteries
Sen Jiang, Haihua Wu, Junying Yin, Zhihua Wei, Jiahao Wu, Lai Wei, Dunfeng Gao, Xin Xu, Yunfang Gao
Abstract
Abstract High‐voltage LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811)‐based Li‐ion batteries (LIBs) with enhanced performance can be achieved by properly tailoring the electrolyte systems. Benzoic anhydride (BA) was proposed here as a promising bifunctional electrolyte additive that can not only construct a robust cathode‐electrolyte interface (CEI) film on the electrode surface but also capture HF/H 2 O in the electrolyte effectively. Compared to the cell without the BA additive, the capacity of Li/NCM811 half‐cell with 1.0 wt % BA was increased from 128.5 to 149.6 mAh g −1 after 200 cycles at 1 C between 3.0 and 4.3 V. Even at a higher cut‐off voltage of 4.5 V, the BA‐containing Li/NCM811 half‐cell delivered a capacity retention of 69 % after 200 cycles, much higher than that of the half‐cell without the additive (56 %). Both theoretical calculation and experimental results verified that the BA additive could be preferentially oxidized to form a stable interface film with high conductivity that protected the NCM811 cathode and suppressed the decomposition of the electrolyte.