Reversible Alkaline Sulfur Cathode Based on Six-Electron Electrochemistry for Advanced Aqueous Sulfur Batteries

Yuqi Guo, Yingqian Chen, Gwendolyn J.H. Lim, Siyu Zhu, Yulia Lekina, Yi Cai, Vivek Verma, Kwok Kiong Chan, J. J.Nicholas Lim, Ernest Jun Jie Tang, Pinit Kidkhunthod, Ming Wah Wong, Yizhong Huang*, Ze Xiang Shen, Madhavi Srinivasan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Aqueous sulfur batteries are promising for high-performance and low-cost energy storage. However, their energy density is limited by low battery voltages due to the negative potential [E0 = −0.51 V vs standard hydrogen electrode (SHE)] of low valent sulfur redox (S0/S2-) and low discharge capacity (∼300 mA h g-1) of high valent sulfur redox (S2O32-/S4O62- or S4+/S0). Herein, we develop a reversible alkaline sulfur cathode via introducing Cu2+ and Zn2+ ion mediators, exhibiting a redox potential above 0 V vs SHE, which is higher than low valent sulfur redox and high specific capacity of 1340 mA h g-1. Furthermore, the proposed rechargeable alkaline sulfur batteries achieve a high operating battery voltage of approximately 1.1 V and rapid reaction kinetics, sustained even at high current densities of up to 10 A g-1. In-depth characterization and DFT calculations reveal that the alkaline sulfur electrochemistry follows a six-electron conversion reaction S ↔ CuS ↔ ZnS + Cu2O ↔ Cu, delivering an energy density of 1168 W h kg-1 and a power density of 8110 W kg-1. This work offers insights into aqueous sulfur electrochemistry and shows an alternative to achieving high energy density aqueous batteries.

Original languageEnglish
Pages (from-to)15522-15536
Number of pages15
JournalACS Nano
Volume19
Issue number16
DOIs
Publication statusPublished - Apr 29 2025
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2025 American Chemical Society.

ASJC Scopus Subject Areas

  • General Materials Science
  • General Engineering
  • General Physics and Astronomy

Keywords

  • aqueous batteries
  • aqueous sulfur batteries
  • high redox potential
  • rapid kinetics
  • sulfur electrochemistry

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