Nonaqueous Electrolytes with Advances in Solvents

Abstract

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 hexafl uorophosphate (LiPF 6 ) 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 fl uorine, 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.

Liquid perfluoropolyether electrolytes with enhanced ionic conductivity for lithium battery applications

“…Perfluorinated small molecules have been investigated as nonflammable electrolyte alternatives to enhance the safety of Li-ion batteries for potential large-scale applications, but they often exhibit low ionic conductivities due to low lithium salt solubility in the solvent. [7] Therefore, similar to phosphate-based additives, fluorinated small molecules have commonly been explored as flame-retardant additives for conventional alkyl carbonate solvents rather than as neat electrolyte solvents. [8] Although safety characteristics are enhanced with these additives, the fluorinated solvent often must be the major component in order to observe nonflammability.…”

Conductivity and Dielectric Studies of Lithium Trifluoromethanesulfonate Doped Polyethylene Oxide-Graphene Oxide Blend Based Electrolytes

“…Increase in electrolytes conductivity has been reported with incorporation of plasticizer with higher dielectric constant [5]. Besides, ES also has low melting point (−17 ∘ C) which can ensure the plasticizer molecules will not solidify at room temperature which may limit the ion mobility [23]. The feasibility of ES in improving conductivity of the PEO based SPE can be investigated further and small loadings of ES contents minimize deterioration of the mechanical properties and the potential stability of the polymer films with the addition of plasticizers [24].…”

A review on conductometric studies of electrolytes in mixed solvent systems to understand ion-ion and ion-solvent interactions

“…Since then lithium hexafluorophosphate (LiPF 6 ) has been used as the electrolyte in Li battery. Makoto Ue and coworkers have worked on lithium hexafluorophosphate (LiPF 6 ) salt dissolved in ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate [58].…”