Novel anion-involved chalcogen conversion chemistries for aqueous multivalent metal batteries

Jingwei Du

AutorIn

Jingwei Du

Titel

Novel anion-involved chalcogen conversion chemistries for aqueous multivalent metal batteries

Zitierfähige Url:

https://nbn-resolving.org/urn:nbn:de:bsz:14-qucosa2-1018251

Erstveröffentlichung

2026

Datum der Einreichung

05.08.2025

Datum der Verteidigung

22.12.2025

Abstract (EN)

The growing global focus on energy sustainability to reduce carbon emissions has driven an increased demand for clean energy sources, such as solar, wind, and wave power. However, their intermittent nature limits effectiveness, necessitating large-scale energy storage for a stable supply. Aqueous multivalent metal batteries (AMMBs) are highly promising for large-scale energy storage due to their low cost, inherent safety, and sustainability. While numerous progresses have been made in multivalent metal anodes in recent years, developing novel cathode chemistries with large capacities and high operating potentials remains critical to further enhance the energy density of AMMBs. In this thesis, we explore new anion-involved multi-electron chalcogen conversion chemistries, demonstrating their potential to improve the specific energy of AMMBs. First, we present a tellurium anion-involved conversion cathode chemistry for aqueous zinc batteries, which delivers a specific capacity of 1223.9 mAh gTe−1 and a high energy density of 1028.0 Wh kgTe−1. A highly concentrated electrolyte (30 mol kg−1 ZnCl2) is revealed to be crucial for initiating the Te redox-amphoteric conversion, as it suppresses the reactivity of H2O and inhibits the undesirable hydrolysis of the Te4+ product. By carrying out multiple operando/ex-situ characterizations, we identify the reversible six-electron Te2−/Te0/Te4+ conversion with TeCl4 as the fully charged product and ZnTe as the fully discharged product. This finding not only enriches the conversion-type battery chemistries but also establishes a critical step in exploring redox-amphoteric materials for aqueous zinc batteries and beyond. Second, we extend our study to the Se cathode because of higher theoretical capacity, working potential, and low cost compared with that of the Te cathode. Specifically, we demonstrate a reversible high-capacity six-electron-conversion Se cathode undergoing a ZnSe↔Se↔SeCl4 reaction, with Br−/Brn− redox couple effectively stabilizing the Zn||Se cell. This Se conversion, initiated in a ZnCl2-based hydrogel electrolyte, presents rapid capacity decay (from 1937.3 to 394.1 mAh gSe−1 after only 50 cycles at 0.5 A gSe−1) primarily due to the dissolution of SeCl4 and its subsequent migration to the Zn anode, resulting in dead Se passivation. To address this, we incorporate the Br−/Brn− redox couple into the Zn||Se cell by introducing bromide salt as an electrolyte additive. The generated Brn− 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 gSe−1 after 50 cycles. Moreover, the Zn||Se cell exhibits a specific capacity of 2077.6 mAh gSe−1 and specific energy of 404.2 Wh kg−1 based on the overall cell reaction. Finally, due to the high abundance (8.2% vs. 0.0075% in Earth's crust) and large specific capacity (2980 mAh g–1 vs. 820 mAh g–1, 8046 mAh cm–3 vs. 5855 mAh cm–3) of aluminium, we further extend the anion-involved chalcogen conversion chemistry to aqueous aluminium battery (AAB). With chlorine-containing electrolyte, we demonstrate Cl− storage of Te electrode based on the conversion mechanism. The Te0/Te4+ conversion redox couple exhibits lower polarization (0.17 V) compared with that in electrolytes with large-size and multi-atom anions (0.56 V in 2 M Al(OTf)3 and 0.57 V in 1 M Al2(SO4)3). Furthermore, we observe a synergistic interaction between Te0/Te4+ and Cl−/Cl0 redox couple, which effectively enhances the cycling performance. This enhancement is likely due to Cl−/Cl0 mediated re-oxidation of Te species that become electrochemically isolated during charge and discharge.

Freie Schlagwörter (DE)

Anionenspeicherung, wässrige Batterie, Chalkogenumwandlung

Freie Schlagwörter (EN)

Anion storage, aqueous battery, chalcogen conversion

Klassifikation (DDC)

540

Klassifikation (RVK)

VN 6057

GutachterIn