(Invited) Magnesium Organic Batteries

Abstract

Magnesium insertion cathodes are predominantly based on chalcogenide materials and possess low energy density due to high molecular weight and low operational voltage. Redox active organic material can be considered as an alternative material, which due to open structure caused by relatively weak intermolecular forces possess much higher gravimetrical energy density. Although, their drawback can be low volumetric energy density since polymers have low density, latter can be compensated with high volumetric density of Mg metal. Redox active organic molecules were considered as a cathode for rechargeable Mg batteries more than decades ago, however their practical application in two electrode cell has been demonstrated with discovery of non-nucleophilic electrolytes which enable reversible stripping and deposition of metallic magnesium. Several different redox active organic materials show potential application, but the most promising direction is use of conjugated carbonyls since predicted theoretical energy density can exceed 700 Wh/kg and batteries show working potential of 2V. Reduction of conjugated carbonyl compounds occurs through the reversible reduction of carbonyl bond as it has been demonstrated by ATR-IR operando measurements. In this presentation, an overview of recent achievements on the field of magnesium organic batteries will be discussed with a focus on remaining problems that has to be solved in the future. Acknowledgement: This work is supported HONDA R&D Europe and by the Slovenian Research Agency (research core funding No. P2-0393 and research project J2-8167).