Cation-Trapping Engineering Tailors Bismuth Selenide to Enable Superior Multivalent Ion Storage via an Optimized Synergistic Dual-Reaction Mechanism.

Aqueous multivalent-ion batteries have garnered considerable attention as a promising alternative to lithium-ion batteries, offering advantages such as low cost, high specific capacity, enhanced safety, and environmental sustainability. However, the development of efficient cathodes remains challenging, constrained by sluggish multivalent-ion diffusion and pronounced structural degradation. Here, we introduce cation-trapping engineering to tailor the topological insulator BiSe (ZnBiSe), enhancing the electrochemical performance by activating additional active sites and expanding the interlayer spacing. Furthermore, comprehensive experimental characterizations reveal that ZnBiSe stores Cu via a "synergistic dual-reaction mechanism", attaining rapid reaction kinetics and high capacity. Accordingly, an excellent rate performance (350 mAh g at 1.0 A g and 241.3 mAh g at 10 A g) and a long cycling life (10,000 cycles at 10 A g) are obtained. Moreover, the prepared quasi-solid-state flexible pouch battery demonstrates superior performance and the ability to operate under various destructive conditions, offering potential utilization in flexible electronic devices.