Issue 10, 2023

A dual-mediator for a sulfur cathode approaching theoretical capacity with low overpotential in aqueous Zn–S batteries

Abstract

Aqueous Zn–S batteries are promising for energy storage. However, the sulfur cathode suffers poor redox kinetics due to the sluggish solid–solid conversion with ZnS. Here, a dual mediator of trimethylphenylammonium iodide (Me3PhN+I) is introduced. Me3PhN+ functions as a dissolution mediator to generate soluble polysulfide intermediates during discharge, allowing a facile solid–liquid–solid path for S. The ZnS to S oxidation during charge is catalyzed by the I/I3 redox mediator, and the reduced I3 solubility by Me3PhN+ prevents shuttling while retaining catalyst power. The sulfur cathode exhibits 1659 mA h g−1 capacity with only 0.34 V overpotential at 0.1 A g−1, and 851 mA h g−1 is retained at 5 A g−1. It is superior to 1066 mA h g−1 capacity and 0.75 V overpotential obtained without Me3PhN+I (0.1 A g−1). With a sulfur loading of 5.1 mg cm−2 and an E/S ratio of 10 μL mgS−1, the sulfur cathode reaches 1623 mA h g−1/8.3 mA h cm−2 capacity and 0.37 V overpotential with the help of Me3PhN+I.

Graphical abstract: A dual-mediator for a sulfur cathode approaching theoretical capacity with low overpotential in aqueous Zn–S batteries

Supplementary files

Article information

Article type
Communication
Submitted
31 May 2023
Accepted
05 Sep 2023
First published
13 Sep 2023

Energy Environ. Sci., 2023,16, 4326-4333

A dual-mediator for a sulfur cathode approaching theoretical capacity with low overpotential in aqueous Zn–S batteries

W. Wu, S. Wang, L. Lin, H. Shi and X. Sun, Energy Environ. Sci., 2023, 16, 4326 DOI: 10.1039/D3EE01749D

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