(Phenylsulfonyl)acetonitrile as a High-Voltage Electrolyte Additive to Form a Sulfide Solid Electrolyte Interface Film to Improve the Performance of Lithium-Ion Batteries

(Phenylsulfonyl)acetonitrile (PSPAN) is investigated as a high-voltage additive to form a solid electrolyte interface (SEI) on an LiCoO2 cathode. The results show that after 100 cycles, the capacity retention of Li/LiCoO2 cells containing 1.0 wt % PSPAN increases from 66.34 to 91.84% and the rate performance of the cells also significantly increases. Linear sweep voltammetry results show that PSPAN can be preferentially oxidized over other solvents. X-ray photoelectron spectroscopy and scanning electron microscopy analyses confirm that PSPAN can form an SEI film containing sulfide on the electrode. The rapidly produced Li2S in combination with other components such as Li2O and LiF forms smaller size particles on the electrode surface and provides more channels for the diffusion of lithium ions, resulting in a more excellent cell performance.