Role of Sulfone Additive in Improving 4.6V High-Voltage Cycling Performance of Layered Oxide Battery Cathode

Capacity of layered lithium nickel-cobalt-manganese oxide (LiNi1-x-yCoxMnyO2) cathode material can increase by raising the charge cut-off voltage above 4.3 V vs. Li/Li+, but it is limited due to anodic instability of conventional electrolyte. We have been screening and evaluating various sulfone-based compounds of dimethyl sulfone (DMS), diethyl sulfone (DES), ethyl methyl sulfone (EMS) as electrolyte additives for high-voltage applications. Here we report improved cycling performance of LiNi0.5Co0.2Mn0.3O2 cathode by the use of dimethyl sulfone (DMS) additive under an aggressive charge condition of 4.6 V, compared to that in conventional electrolyte, and cathode-electrolyte interfacial reaction behavior. The cathode with DMS delivered discharge capacities of 198-173 mAhg(-1) over 50 cycles and capacity retention of 84%. Surface analysis results indicate that DMS induces to form a surface protective film at the cathode and inhibit metal-dissolution, which is correlated to improved high-voltage cycling performance.