A novel dimethyl sulfoxide/1,3-dioxolane based electrolyte for lithium/carbon fluorides batteries with a high discharge voltage plateau

A novel dimethyl sulfoxide/1,3-dioxolane (DMSO/1,3-DO) based electrolyte is proposed for lithium/carbon fluorides (Li/CF x ) batteries to enhance the discharge voltage plateau and energy density. Conductivities of the electrolyte of 1   mol   L −1 LiBF 4 /DMSO+1,3-DO with different volume ratios are not identical, which have a maximum of 14.85   mS   cm −1 . From the tests of galvanostatic discharge, the discharge voltage plateau of the Li/CF x battery with an electrolyte of 1   mol   L −1 LiBF 4 /DMSO+1,3-DO (5:5, v:v) can reach 2.69   V at 0.1   C, delivering a maximum discharge capacity of 831   mAh   g −1 and the highest energy density of 2196   Wh   kg −1 . Compared to Li/CF x batteries with an electrolyte of 1   mol   L −1 LiBF 4 /PC+DME (5:5, v:v), the energy density of Li/CF x batteries with an electrolyte of 1   mol   L −1 LiBF 4 /DMSO+1,3-DO (5:5, v:v) has been improved more than 12%. With the help of XRD, SEM, TEM, EIS, FT-IR and GC-MS analysis, the results of this work suggest that DMSO/1,3-DO based electrolyte can significantly improve the discharge performance of Li/CF x batteries and keep a good electrochemical stability during discharge. The main reason for improvement of discharge performance is decreasing of both the overpotential of electrochemical polarization of CF x cathodes during discharge and the overpotential of ohmic polarization by increasing the ion conductivity of electrolyte.