Six-electron-conversion selenium cathodes stabilized by dead-selenium revitalizer for aqueous zinc batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 40251148.
- Also identified by DOI 10.1038/s41467-025-58859-3 and PMC identifier 12008412.
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Abstract
Aqueous zinc batteries are attractive for large-scale energy storage due to their inherent safety and sustainability. However, their widespread application has been constrained by limited energy density, underscoring a high demand of advanced cathodes with large capacity and high redox potential. Here, we report a reversible high-capacity six-electron-conversion Se cathode undergoing a ZnSe↔Se↔SeCl<sub>4</sub> reaction, with Br<sup>-</sup>/Br<sub>n</sub><sup>-</sup> redox couple effectively stabilizes the Zn | |Se cell. This Se conversion, initiated in a ZnCl<sub>2</sub>-based hydrogel electrolyte, presents rapid capacity decay (from 1937.3 to 394.1 mAh g<sub>Se</sub><sup>-1</sup> after only 50 cycles at 0.5 A g<sub>Se</sub><sup>-1</sup>) primarily due to the dissolution of SeCl<sub>4</sub> and its subsequent migration to the Zn anode, resulting in dead Se passivation. To address this, we incorporate the Br<sup>-</sup>/Br<sub>n</sub><sup>-</sup> redox couple into the Zn | |Se cell by introducing bromide salt as an electrolyte additive. The generated Br<sub>n</sub><sup>-</sup> species acts as a dead-Se revitalizer by reacting with Se passivation on the Zn anode and regenerating active Se for the cathode reaction. Consequently, the cycling stability of the Zn | |Se cell is improved, maintaining 1246.8 mAh g<sub>Se</sub><sup>-1</sup> after 50 cycles. Moreover, the Zn | |Se cell exhibits a specific capacity of 2077.6 mAh g<sub>Se</sub><sup>-1</sup> and specific energy of 404.2 Wh kg<sup>-1</sup> based on the overall cell reaction.