Electrochemical performances of a novel lithium bis(oxalate)borate-based electrolyte for lithium-ion batteries with LiFePO4 cathodes

Abstract

Lithium bis(oxalate)borate (LiBOB) is a promising salt for lithium-ion batteries. However, it is necessary to exert the electrochemical performance of LiBOB by the appropriate solvent. With dimethyl sulfite (DMS) as mixed solvents, the electrochemical behavior of γ-butyrolactone (GBL) with LiBOB is studied in this paper. It shows that LiBOB-GBL/DMS electrolyte has high oxidation potential (>5.3 V) and satisfactory conductivities. When used in lithium and mesophase carbon microbead cells, the novel electrolyte exhibits not only excellent film-forming characteristics but also low impedances of the interface films. Besides, when used in LiFeO4/Li cells, compared to the cell with the electrolyte system of 1 mol L−1 LiPF6–ethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1, v/v), LiBOB-based electrolyte exhibits several advantages, such as more stable cycle performance at room temperature and higher mean voltage.