Coulombic Condensation of Liquefied Gas Electrolytes for Li Metal Batteries at Ambient Pressure

Abstract

The concept of employing highly concentrated electrolytes has been widely incorporated into electrolyte design, due to their enhanced Li-metal passivation and oxidative stability compared to their diluted counterparts. However, issues such as high viscosity and sub-optimal wettability, compromise their suitability for commercialization. In this study, we present a highly concentrated dimethyl ether-based electrolyte that appears as a liquid phase at ambient conditions via Li+ - solvents ion-dipole interactions (Coulombic condensation). Unlike conventional high salt concentration ether-based electrolytes, it demonstrates enhanced transport properties and fluidity. The anion-rich solvation structure also contributes to the formation of a LiF-rich salt-derived solid electrolyte interphase, facilitating stable Li metal cycling for over 1000 cycles at 0.5 mA cm−2, 1 mAh cm−2 condition. When combined with a sulfurized polyacrylonitrile (SPAN) electrode, the electrolyte effectively reduces the polysulfide shuttling effect and ensures stable performance across a range of charging currents, up to 6 mA cm−2. This research underscores a promising strategy for developing an anion-rich, high concentration ether electrolyte with decreased viscosity, which supports a Li metal anode with exceptional temperature durability and rapid charging capabilities.