Reversible electrochemical oxidation of sulfur in ionic liquid for high-voltage Al-S batteries

Huan Li; Rongwei Meng; Yong Guo; Biao Chen; Yan Jiao; Chao Ye; Yu Long; Anton Tadich; Quan-Hong Yang; Mietek Jaroniec; Shi-Zhang Qiao

doi:10.1038/s41467-021-26056-7

Reversible electrochemical oxidation of sulfur in ionic liquid for high-voltage Al-S batteries

Nat Commun. 2021 Sep 29;12(1):5714. doi: 10.1038/s41467-021-26056-7.

Authors

Huan Li^#¹, Rongwei Meng^#², Yong Guo², Biao Chen³, Yan Jiao¹, Chao Ye¹, Yu Long², Anton Tadich⁴, Quan-Hong Yang², Mietek Jaroniec⁵, Shi-Zhang Qiao⁶

Affiliations

¹ School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, SA, 5005, Australia.
² Nanoyang Group, State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China.
³ School of Materials Science and Engineering and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, 300350, Tianjin, China.
⁴ Australian Synchrotron (ANSTO), 800 Blackburn Road, Clayton, VIC, 3168, Australia.
⁵ Department of Chemistry and Biochemistry & Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA.
⁶ School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, SA, 5005, Australia. s.qiao@adelaide.edu.au.

^# Contributed equally.

Abstract

Sulfur is an important electrode material in metal-sulfur batteries. It is usually coupled with metal anodes and undergoes electrochemical reduction to form metal sulfides. Herein, we demonstrate, for the first time, the reversible sulfur oxidation process in AlCl₃/carbamide ionic liquid, where sulfur is electrochemically oxidized by AlCl₄^- to form AlSCl₇. The sulfur oxidation is: 1) highly reversible with an efficiency of ~94%; and 2) workable within a wide range of high potentials. As a result, the Al-S battery based on sulfur oxidation can be cycled steadily around ~1.8 V, which is the highest operation voltage in Al-S batteries. The study of sulfur oxidation process benefits the understanding of sulfur chemistry and provides a valuable inspiration for the design of other high-voltage metal-sulfur batteries, not limited to Al-S configurations.