Reversible S0 /MgSx Redox Chemistry in a MgTFSI2 /MgCl2 /DME Electrolyte for Rechargeable Mg/S Batteries

Tao Gao; Singyuk Hou; Fei Wang; Zhaohui Ma; Xiaogang Li; Kang Xu; Chunsheng Wang

doi:10.1002/anie.201708241

Reversible S⁰ /MgS_x Redox Chemistry in a MgTFSI₂ /MgCl₂ /DME Electrolyte for Rechargeable Mg/S Batteries

Angew Chem Int Ed Engl. 2017 Oct 16;56(43):13526-13530. doi: 10.1002/anie.201708241. Epub 2017 Sep 22.

Authors

Tao Gao¹, Singyuk Hou¹, Fei Wang¹, Zhaohui Ma¹, Xiaogang Li¹, Kang Xu², Chunsheng Wang¹

Affiliations

¹ Department of Chemical and Bimolecular Engineering, University of Maryland, College Park, MD, 20740, USA.
² Electrochemistry Branch, Power and Energy Division Sensor and Electron Devices Directorate, U.S. Army Research Laboratory, Adelphi, MD, 20783, USA.

PMID: 28849616
DOI: 10.1002/anie.201708241

Abstract

The redox chemistry of magnesium and its application in rechargeable Mg batteries has received increasing attention owing to the unique benefits of Mg metal electrodes, namely high reversibility without dendrite formation, low reduction potentials, and high specific capacities. The Mg/S couple is of particular interest owing to its high energy density and low cost. Previous reports have confirmed the feasibility of a rechargeable Mg/S battery; however, only limited cycling stability was achieved, and the complicated procedure for the preparation of the electrolytes has significantly compromised the benefits of Mg/S chemistry and hindered the development of Mg/S batteries. Herein, we report the development of the first rechargeable Mg/S battery with a MgTFSI₂ /MgCl₂ /DME electrolyte (DME=1,2-dimethoxyethane, TFSI=bis(trifluoromethanesulfonyl)imide) and realize the best cycling stability among all reported Mg/S batteries by suppressing polysulfide dissolution. Mechanistic studies show that the battery works via S⁰ /MgS_x redox processes and that the large voltage hysteresis is mainly due to the Mg anode overpotential.

Keywords: batteries; electrochemistry; magnesium; polysulfide; sulfur.

Publication types

Research Support, Non-U.S. Gov't