Change of Conductivity with Salt Content, Solvent Composition, and Temperature for Electrolytes of LiPF[sub 6] in Ethylene Carbonate-Ethyl Methyl Carbonate

Abstract

We measured the electrolytic conductivities of the electrolytes of LiPF6 in ethylene carbonate-ethyl methyl carbonate at different salt contents, solvent compositions, and temperatures in the ranges of their practical values. To these data, we fitted a fourth degree trivariate polynomial and obtained a close fit. We then plotted this function as surface and contour plots in the coordinates of salt content and solvent composition for a series of temperatures. These plots showed the change of conductivity with the simultaneous changes of salt content and solvent composition and the influence of temperature on this change, thus mapping the locations for the optimal combinations of salt content and solvent composition for maximum conductivity of the electrolytes at desired temperatures. Here we also discuss and interpret qualitatively the trends found in the change of conductivity with salt content, solvent composition, and temperature, based on the dependency on the same variables of these three factors: the number of dissociated ions in the electrolyte, the dielectric constant of the solvent, and the viscosity of the electrolyte. © 2001 The Electrochemical Society. All rights reserved.

The mechanism of HF formation in LiPF6 based organic carbonate electrolytes

“…A WVASE32® software using a Marquardt-Levenberg algorithm was used to interpret the ellipsometry results. The thickness of SiO 2 layers was determined using a simple two layer Si/SiO 2 model and optical constants for SiO 2 and Si found in the literature. The HF concentration in the electrolyte has been calculated using following empirical formula [20] It is observed that the HF formation in the electrolyte does not start immediately but after slightly more than 70 hours.…”

“…[1][2][3][4][5] However, despite the relatively high thermal stability in dry inert atmosphere up to 107°C where only solid lithium fluoride and PF 5 are formed [6], this salt suffers from degradation upon exposure to traces of water, moisture or alcohols [7]. In literature it is proposed that the reaction starts with the decomposition of LiPF 6 [7][8][9][10]: (1) to form phosphorous pentafluoride which can react with water to form HF and POF 3 .…”

Nonaqueous Electrolytes with Advances in Solvents

“…The addition effect of the hydrofl uoroethers such as CF 3 in Scheme 2.10 to EC-DEC or EC-DEC-PC was investigated using graphite electrodes [ 12 , 32 ]. The charge capacities higher than in EC/DEC were observed in these electrolytes when the reduction potentials of the fl uoroethers are slightly higher than that of EC.…”

Reactive Distillation for Multiple-Reaction Systems: Optimisation Study Using an Evolutionary Algorithm

“…Additionally, DEC can be used as a raw material for the manufacture of polycarbonates (Bolon and Hallgren, 1984). Like EMC, DEC is widely used as a co-solvent in alkali metal-ion batteries (Ding et al, 2001). Most importantly, DEC is considered to be one of the best alternatives for methyl tert-butyl ether (MTBE) as an oxygen-containing fuel additive (Dunn et al, 2002;Pacheco and Marshall, 1997).…”