Hetero-Chalcogen Chemistry Enables Reversible Six-Electron Redox for an Energetic Tellurium Aqueous Battery.

Abstract

Tellurium (Te)-based redox chemistries are attractive for high-energy aqueous batteries due to their multielectron transfer and high theoretical capacity, but their available capacities are hindered by the high oxidation energy barrier of Te. Here, we propose a heterochalcogen strategy by introducing electronegative Se to regulate the electronic structure of Te. Combined in situ characterizations, synchrotron spectroscopy, and theoretical simulation reveal the formation of Te²⁺ intermediates and the charge redistribution via Se doping, facilitating the complete six-electron K₂Te₄O₉ ↔ K₂Te conversion. As a result, the optimized Se-doped Te electrodes deliver a high reversible capacity of 1186 mAh g^-1 with an exceptional Te utilization rate of 98.6%, unprecedented rate performance of 688 mAh g^-1 at 6 A g^-1, and stable cycling over 500 cycles. This work demonstrates the effectiveness of heterochalcogen engineering in overcoming intrinsic limitation of Te-based chemistry and highlights a promising pathway to unlock multielectron chalcogen chemistry for the development of next-generation high-energy aqueous batteries.