Nonaqueous Electrolytes with Advances in Solvents

Most of the liquid electrolytes used in commercial lithium-ion (Li-ion) cells are nonaqueous solutions, in which roughly 1 mol dm−3 of lithium hexafluorophosphate (LiPF6) salt is dissolved in a mixture of carbonate solvents selected from cyclic carbonates—ethylene carbonate and propylene carbonate—and linear carbonates—dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate. In Sect. 2.1, the physicochemical properties of these carbonate solvents are listed and the phase diagrams and electrolytic conductivity data of mixed carbonate solvent systems are given. However, recent market demands for Li-ion cells with higher energy, higher power, and higher safety requires new solvents to improve the performance of cells in electrolytes based on carbonate solvents only. New heteroatom-containing organic solvents including fluorine, boron, phosphorous, and sulfur, which have been applied to lithium cells in recent years, are reviewed from the viewpoints of synthesis, physicochemical properties, and cell performance by four authors.