Electrochemical performances of two kinds of electrolytes based on lithium bis(oxalate)borate and sulfolane for advanced lithium ion batteries

Abstract

Lithium bis(oxalato)borate (LiBOB) is a promising salt for lithium ion batteries. However, to achieve better electrochemical performance of LiBOB, the development of appropriate electrolytes is essential. In this work, the electrochemical behaviors of sulfolane (SL) with LiBOB were studied by employment of dimethyl sulfite (DMS) and diethyl sulfite (DES) as mixed solvents, respectively. Both of the LiBOB-based electrolytes show high oxidation potentials (>5.5V), and good conductivities. When used in Li/MCMB (mesophase carbon microbeads) cells, these two kinds of novel electrolytes exhibit not only excellent film-forming characteristics, but also low impedances of the interface films. Besides, when used in LiFePO4/Li cells, compared to the cell with the electrolyte system of 1M LiPF6-EC/DMC (1:1, v/v), both of the LiBOB-based electrolytes exhibit several advantages, such as more stable cycle performance even at elevated temperature, and higher mean voltage.