New small molecule gel electrolyte with high ionic conductivity for Li–S batteries

A new small molecule gel electrolyte is developed by trapping an organic mixture of 1,3-dioxolane and dimethyl ether with lithium bistrifluoromethanesulfonimide (LiTFSI). The electrochemical properties of the resulting gel electrolyte are investigated. AC impedance spectroscopy reveals that the ionic conductivity of the as-prepared gel electrolyte containing 8.3 wt% small molecules displays a maximum value of 6.43 × 10−3 S cm−1 at room temperature. The possible interaction between molecule and LiTFSI was investigated by the NMR spectra and a speculated transmission mechanism was also discussed. The sulfur cathode with the as-prepared small molecule gel electrolyte displays the initial discharge specific capacity of 1008 mAh g−1 (0.1 C). The Li–S cells assembled with the as-prepared electrolyte membrane display an excellent cycle performance and coulombic efficiency. The electrolyte membrane played an important role in restraining the shuttle effect of polysulfides. These experimental results demonstrate the possibility and potential as new solid electrolyte for Li–S batteries to replace the traditional polymer gel electrolyte.