High interfacial charge storage capability of carbonaceous cathodes for Mg batteries
Journal article, Peer reviewed
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Original versionACS Nano. 2018, 12 (3), 2998-3009. 10.1021/acsnano.8b00753
A rechargeable Mg battery where the capacity mainly originates from reversible reactions occurring at the electrode/electrolyte interface efficiently avoids the challenge of sluggish Mg intercalation encountered in conventional Mg batteries. The interfacial reactions in a cell based on microwave-exfoliated graphite oxide (MEGO) as the cathode and all phenyl complex (APC) as electrolyte are identified by quantitative kinetics analysis as a combination of diffusion-controlled reactions involving ether solvents (esols) and capacitive processes. During magnesiation, esols in APC electrolytes can significantly affect the electrochemical reactions and charge transfer resistances at the electrode/electrolyte interface and thus govern the charge storage properties of the MEGO cathode. In APC–tetrahydrofuran (THF) electrolyte, MEGO exhibits a reversible capacity of ∼220 mAh g–1 at 10 mA g–1, while a reversible capacity of ∼750 mAh g–1 at 10 mA g–1 was obtained in APC-1,2-dimethoxyethane (DME) electrolyte. The high capacity improvement not only points to the important role of the esols in the APC electrolytes but also presents a Mg battery with high interfacial charge storage capability as a very promising and viable competitor to the conventional intercalation-based batteries.