Predicting the Solubility of Sulfur: A COSMO‐RS‐Based Approach to Investigate Electrolytes for Li–S Batteries

Abstract

Lithium-sulfur (Li-S) batteries are in theory, from their basic reactions, very promising from a specific energy density point-of-view, but have bad power rate capabilities. The dissolution of sulfur from the C/S cathodes into the electrolyte is a rate determining and crucial step for the functionality. So far, time-consuming experimental methods, such as HPLC/UV, have been used to quantify the corresponding solubilities. Here, we use a computational fluid phase thermodynamics approach, the conductor-like screening model for real solvents (COSMO-RS), to compute the solubility of sulfur in different binary and ternary electrolytes. By using both explicit and implicit solvation approaches for LiTFSI containing electrolytes a deviation <0.4 log units was achieved vs. experimental data -in the range of experimental error and hence proves COSMO-RS to be a tool for exploring novel Li-S battery electrolytes.

Monitoring Polysulfide Solubility and Diffusion in Fluorinated Ether‐Based Electrolytes by Operando Raman Spectroscopy

“…940 cm −1 , due to C−O and C−C stretching vibrations, broadens during the formation of short‐chain PS. This hints to PS solvation by DOL rather than TFEE, in agreement with reports showing that the solubility of both LiTFSI and PS in TFEE is very low . This is further strengthened by the peak being at 452 cm −1 in TFEE, slightly up‐shifted vs .…”

Ionic Liquids and their Polymers in Lithium‐Sulfur Batteries

“…This includes implementing IL based electrolytes to reduce polysulfide solubility, coating of the Li‐metal anode with PILs to offer surface protection, and using PIL as a cathode binder to improve cycling stability. Much of this work is the result of a collaboration between partners within the HELIS (High energy lithium sulphur cells and batteries) consortium, an EU H2020 funded project for the development Li−S batteries for commercial applications …”

“…Much of this work is the result of a collaboration between partners within the HELIS (High energy lithium sulphur cells and batteries) consortium, an EU H2020 funded project for the development LiÀS batteries for commercial applications. [6,11,14,[38][39][40][41][42]…”

A Newly Designed Composite Gel Polymer Electrolyte Based on Poly(Vinylidene Fluoride‐Hexafluoropropylene) (PVDF‐HFP) for Enhanced Solid‐State Lithium‐Sulfur Batteries

“…Recently,r esearchers have developed different strategies to overcome these stubborn problemsi ncluding modification of Li metal anodes, [10][11][12] sulfur cathodes, [8,[13][14][15][16] as well as innovation of electrolytes. [17][18][19][20] Typically,o ver recent years,g reat efforts have been made to fabricate solid-state electrolytes, which can furtheri mprovet he energy density and virtually eliminate the risk of fireore xplosion. [10,11,19] As one of the most favorable solid state electrolytes, gel polymer electrolytes (GPE) have been widely studied because of their flexibility,g ood interfacial compatibility, and excellent electrochemical properties.…”

“…Despite these advantages, the development of Li−S batteries still face great challenges including low conductivity of the sulfur cathode, severe “shuttle effect” of intermediate polysulfides in liquid electrolyte, and safety problems arising from lithium dendrites that can grow through the electrolyte layer and lead to short‐circuits by penetrating the membrane. Recently, researchers have developed different strategies to overcome these stubborn problems including modification of Li metal anodes, sulfur cathodes, as well as innovation of electrolytes . Typically, over recent years, great efforts have been made to fabricate solid‐state electrolytes, which can further improve the energy density and virtually eliminate the risk of fire or explosion …”