Physico-Chemical Properties of LiFSI Solutions I. LiFSI with Valeronitrile, Dichloromethane, 1,2-Dichloroethane, and 1,2-Dichlorobenzene

Abstract

Lithium bis­(fluorosulfonyl)­imide (LiFSI) is a novel electrolyte for lithium-ion batteries. Valeronitrile (VN) is a good solvent for LiFSI, and dichloromethane (DCM), 1,2-dichloroethane (DCE), and 1,2-dichlorobenzene (DCB), are interesting antisolvents for crystallization. Physico-chemical data for the design of LiFSI production processes, in which these components are used, is lacking. Therefore, the solubility of LiFSI in VN, as well as in binary solvent mixtures VN + (DCM, DCE, DCB) was measured at temperatures between 278 and 343 K and concentrations of LiFSI up to 0.52 mol mol–1. Furthermore, vapor–liquid equilibria of the systems VN–DCE (at 200 mbar) and VN–DCB (at 200, 300, and 450 mbar) were studied. Also, the density and shear viscosity of solutions of LiFSI in VN were measured at temperatures between 293 and 333 K and concentrations of LiFSI up to 0.5 mol mol–1.

Spectroscopic investigations of solutions of lithium bis(fluorosulfonyl) imide (LiFSI) in valeronitrile

“…However, acetonitrile has a comparatively low normal boiling point, which is undesired in many applications. Therefore, larger n-alkyl nitriles, such as n-valeronitrile (VN), which was studied here, are also attractive as solvents for LiB [17].…”

A Fully Methylated Cyclic Ether Solvent Enables Graphite Anode Cycling at Low Temperatures

“…Based on previous valuable endeavors, some free-EC based electrolytes are proposed to enlarge the temperature range of the electrolyte by employing linear carboxylic esters as cosolvents. These solvents such as ethyl acetate (EA), dichloromethane (DCM), ethyl trifluoroacetate (ETFA), and methylpropionate (MP) usually possess low freezing point and low viscosity. − For example, the ETFA-based electrolyte with weakly solvated ability remained in a liquid state at a super low temperature of −60 °C, and a reversible capacity of 183 mAh/g was obtained for Li||Gr cell at −30 °C . However, the intrinsic electrophilicity of carboxyl group in esters usually leads to inferior interfacial stability to lithiated GA. Solvation structure regulation or electrolyte optimization by adding additives is needed to improve the interfacial stability of esters. , Instead, ether-based solvents usually possess low melting point, low viscosity, and good reductive ability to graphite .…”