Studies on Co-oxidation resistances of electrolytes based on sulfolane and lithium bis(oxalato)borate

Abstract

How to exert the high-voltage performance of LiNi_0.5Mn_1.5O₄ and break through the bottleneck effect of corresponding electrolyte have become key points in advanced lithium-ion battery. Lithium bis(oxalato) borate (LiBOB) and sulfolane (SL) are chosen as additives to investigate their effects on the electrochemical performance of lithium-ion battery with LiNi_0.5Mn_1.5O₄ cathode. The quantum chemistry calculation theory shows that oxidation potential of SL–BOB^– is dramatically increased, consistent with the experimental result in CV measurement. Meanwhile, results of CV and charge–discharge cycling indicate that LiBOB and SL would be involved in the initial oxidation reaction to form an effective solid electrolyte interface film on surfaces of the cathode electrode thus enhance the cycling performance of LiNi_0.5Mn_1.5O₄/Li cells. Electrochemical impedance spectroscopy data proves that SL is beneficial to resistance decrease. All these data will become important corroborations that the combined electrolyte LiBOB and SL have good oxidation resistances.