A novel imidazole-based electrolyte additive for improved electrochemical performance of high voltage nickel-rich cathode coupled with graphite anode lithium ion battery

1,1′-sulfonyldiimidazole (SDM) has been investigated as a novel carbonate-based electrolyte additive for high voltage nickel-rich cathode chemistry, graphite/LiNi0.5Co0.2Mn0.3O2 cells. Upon cycling at high voltage for 50 cycles, graphite/LiNi0.5Co0.2Mn0.3O2 cells with SDM containing electrolyte have superior cycling performance than the cells with baseline electrolyte, specifically, 96.9% and 73.1% capacity retention, respectively. Moreover, cells with 0.25 wt. % SDM have lower impedance and better elevated temperature storage performance as well. The functional mechanism of electrolyte containing SDM on improved cycling performance is elucidated with ex-situ analytical techniques, including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and fourier transform infrared spectroscopy (FTIR), etc. The surface analysis result reveals that SDM has been involved into the surface film forming on the LiNi0.5Co0.2Mn0.3O2 cathode and graphite anode as well, which can simultaneously provide protection for both cathode and anode upon cycling to high voltage, leading to enhanced cyclability of the high voltage (4.5 V vs. Li/Li+) graphite/LiNi0.5Co0.2Mn0.3O2 cells with the presence of SDM.