Active Mechanism of the Interphase Film-Forming Process for an Electrolyte Based on a Sulfolane Solvent and a Chelato-Borate Complex

Synergistic effect of sulfolane-based composite polymer electrolyte and vinylidene carbonate/lithium difluoro(oxalato)borate interface modification on LiCoO2 cathode

LiCoO2 (LCO) is a prominent high-voltage cathode material due to its exceptional energy density and impressive theoretical specific capacity of 274 mAh g-1. However, challenges such as irreversible structural phase transitions, loss of reactive oxygen, and cobalt dissolution can lead to unstable interfaces between the electrolyte and the LCO cathode. In this study, sulfolane (SUL)-based composite polymer electrolytes (CPEs) were synthesized through in-situ polymerization, and the LCO cathode was modified using vinylidene carbonate (VC) and lithium difluoro(oxalato)borate (LiDFOB). The synergistic effects of SUL and VC/LiDFOB facilitated the formation of a more stable cathode-electrolyte interface (CEI) layer. Consequently, the Li/EFHTL-15 %SUL/LCO-VC-LiDFOB cell demonstrated excellent reversible cycling performance, achieving 86.36 % capacity retention after 300 cycles at 0.5C within a voltage range of 2.8-4.4 V at 25 ℃. This work provides a viable approach for enhancing the interface stability of the LCO cathode in CPEs.

Structurally integrated asymmetric polymer electrolyte with stable Janus interface properties for high-voltage lithium metal batteries

Solid-state polymer electrolytes are outstanding candidates for next-generation lithium metal batteries in the realm of high specific energy densities, high safeties and tight contact with electrodes. However, their applications are still hindered by the limitations that no single polymer is electrochemically stable with the oxidizing high-voltage cathode and the highly reductive Li anode, simultaneously. Herein, a bilayer asymmetric polymer electrolyte (SL-SPE) without accessional interface resistance that using poly (ethylene glycol) diacrylate (PEGDA) as a "bridge" to connect the sulfonyl (OS = O)-contained oxidation-tolerated layer and polyether-derived reduction-tolerated layer (SPE), is proposed and synthesized by sequential two-step UV polymerizations. SL-SPE can provide widened electrochemical stability window up to 5 V, while simultaneously deploying a stable Janus interface property. Eventually, the superior high-voltage (4.4 V) cycling durability can be displayed in LiNi_0.6Co_0.2Mn_0.2O₂|SL-SPE|Li batteries. This finding provides a bran-new idea for designing multifunctional polymer electrolytes in the application of solid-state batteries.

Solvate Ionic Liquids: Assessing the Possibility of Determining the Composition by Means of Gas–Liquid Chromatography

Abstract

A study is performed of the possibility of using gas–liquid chromatography (GLC) to determine the composition of solutions of lithium salts in aprotic dipolar solvents and solvate ionic liquids. The objects of study are solutions of lithium perchlorate and lithium trifluoromethanesulfonate in sulfolane and solvate complexes of lithium perchlorate with sulfolane obtained in two ways: direct interaction of the initial components in a given molar ratio and interaction of the components in a common solvent with its subsequent removal via evaporation. It is shown that GLC is a convenient way of determining the content of a solvating solvent in the composition of solutions and solvate ionic liquids. The presence of lithium salt in the analyzed solutions does not affect the period of retention; instead, it raises the degree of asymmetry of the chromatographic peak of the solvent and manifestation of the tailing effect. It is found that the presence of salt in the considered system also does not reduce the accuracy of determining the solvent content. The error in determining the content of solvent in solutions of lithium salts and solvate complexes by GLC is no greater than 1%.

Studies of air-exposure effects and remediation measures on lithium bis(oxalato)borate

Changes in properties for air-exposure lithium bis(oxalate)borate and reparability study by heating method.