Title: Thermodynamics and Kinetics of Sulfur Cathode during Discharge in MgTFSI₂ -DME Electrolyte

Abstract

Rechargeable magnesium/sulfur battery is of significant interest because its energy density (1700 Wh kg^-1 and 3200 Wh L^-1) is among the highest of all battery chemistries (lower than Li/O₂ and Mg/O₂ but comparable to Li/S), and Mg metal allows reversible operation (100% Coulombic efficiency) with no dendrite formation. This great promise is already justified in some early reports. However, lack of mechanistic study of sulfur reaction in the Mg cation environment has severely hindered our understanding and prevents effective measures for performance improvement. In this work, the very first systematic fundamental study on Mg/S system is conducted by combining experimental methods with computational approach. The thermodynamics and reaction pathway of sulfur cathode in MgTFSI₂–DME electrolyte, as well as the associated kinetics are thoroughly investigated. The results here reveal that sulfur undergoes a consecutive staging pathway in which the formation and chain-shortening of polysulfide occur at early stage accompanied by the dissolution of long-chain polysulfide, and solid-state transition from short-chain polysulfide to magnesium sulfide occurs at late stage. Finally, the former process is much faster than the latter due to the synergetic effect of the mediating effect of dissolved polysulfide and the fast diffusion of Mg ion in the amorphous intermediate.

Authors:

Gao, Tao ^[1]; Ji, Xiao ^[1]; Hou, Singyuk ^[1]; Fan, Xiulin ^[1]; Li, Xiaogang ^[1]; Yang, Chongying ^[1]; Han, Fudong ^[1]; Wang, Fei ^[1]; Jiang, Jianjun ^[2]; Xu, Kang ^[3]; Wang, Chunsheng ^[1]

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+ Show Author Affiliations

1. Univ. of Maryland, College Park, MD (United States). Chemical and Biomolecular Engineering
2. Huazhong Univ. of Science and Technology, Wuhan, Hubei (China). School of Optical and Electronic Information
3. U.S. Army Research Lab., Adelphi, MD (United States). Electrochemistry Branch, Power and Energy Division Sensor and Electron Devices Directorate

Publication Date:

Thu Nov 30 00:00:00 EST 2017

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Nanostructures for Electrical Energy Storage (NEES)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1470667

Alternate Identifier(s):

OSTI ID: 1410706

Grant/Contract Number:  

SC0001160

Resource Type:

Accepted Manuscript

Journal Name:

Advanced Materials

Additional Journal Information:

Journal Volume: 30; Journal Issue: 3; Related Information: NEES partners with University of Maryland (lead); University of California, Irvine; University of Florida; Los Alamos National Laboratory; Sandia National Laboratories; Yale University; Journal ID: ISSN 0935-9648

Publisher:

Wiley

Country of Publication:

United States

Language:

English

Subject:

25 ENERGY STORAGE; bio-inspired; energy storage (including batteries and capacitors); defects; charge transport; synthesis (novel materials); synthesis (self-assembly); synthesis (scalable processing); kinetics; magnesium battery; reaction mechanism; sulfur; thermodynamics