(669b) Electrodeposition from Electrolytes with Increased Thermal Stability for Magnesium Batteries

The development of portable electronics and electric vehicles has contributed to increased demands for battery materials and improved battery performance. This led to the advancement of new types of batteries, including high energy density batteries that use metal anodes. Magnesium, in particular, is an attractive anode material due to its widespread abundance and high theoretical volumetric capacity (3833 mAh/cm³ versus 2062 mAh/cm³ for lithium). The electrochemistry at the magnesium surface is different from lithium; the magnesium surface is readily passivated in the presence of common salts and solvents whereas lithium systems form a lithium-ion conducting solid electrolyte interphase. High performing electrolytes are often solubilized in tetrahydrofuran (THF), an extremely volatile solvent. This study focuses on magnesium electrodeposition in sulfone-ether mixtures and gel matrices in order to increase the thermal stability of said electrolytes. Herein we report the use of sulfone-ether mixtures to increase the thermal equilibration of non-nucleophilic complexes and the electrochemical deposition/dissolution of magnesium metal for each complexation. The deposition morphology is studied as a function of the chemical structure of the sulfone and adsorption layer. We report gel matrices with covalently bound anions that have been designed to promote magnesium ion conduction and to form an active magnesium chloride species that participates in magnesium electrodeposition.