Effect of sulfolane and lithium bis(oxalato)borate-based electrolytes on the performance of spinel LiMn2O4 cathodes at 55 °C

Abstract

To seek a promising candidate electrolyte at elevated temperature for lithium manganese oxide (LiMn2O4)/Li cells, the electrochemical performance of 0.7 mol L−1 LiBOB (lithium bis(oxalate)borate)-SL (sulfolane)/DEC (diethyl carbonate) (1:1, in volume) electrolyte was studied at 55 °C. The Mn dissolution in electrolyte was analyzed by inductively coupled plasma (ICP) analysis. AC impedance measurement and scanning electron microscopy (SEM) analysis were used to analyze the formation of the surface film on the LiMn2O4 electrode. The results demonstrate that the LiBOB-SL/DEC electrolyte can slow down the dissolution and erosion of Mn ions, and decrease the interface impedance. Moreover, the LiBOB-SL/DEC electrolyte could obviously improve the capacity retention, the operating voltage (4.05 V), and the rate performance of LiMn2O4/Li cells.