Nonaqueous Magnesium Electrolyte Intermediates and Kinetics

Abstract

Nonaqueous Magnesium Ion batteries are a promising strategy to overcome the shortcomings of Li ion batteries given magnesium’s lowered abundance, cost, environmental impact and increased energy density and charge-carrying capabilities. Multivalent systems are challenging to study and a mechanistic understanding of how these types of electrolytes function is hazy at best. Where studies have attempted to better characterize the mechanism of charge transfer, details of electron movement are not explicitly reported.Chemical steps are often reported to precede electron transfer steps as well, but the exact nature of these chemical steps have not been proven or well described yet either. The studies herein hope to bridge some of these gaps in knowledge for magnesium electrolyte systems with studies of kinetics and intermediate formation. The highly contested Mg+ intermediate was observed to form during electrodeposition of Mg for all, and during dissolution in some of the studied electrolytes which included three non-halogenated Mg(TFSI)2electrolytes in various organic solvents and a more traditional halogen-based Grignard APC electrolyte.