Interlayer engineering-induced charge redistribution in Bi₂Te₃ toward efficient Zn²⁺ and NH₄ ⁺ storage

Bismuth-based materials show promise for aqueous energy storage systems due to their unique layered structures and high storage capacity. Some bismuth-based materials have been applied to store Zn²⁺ or NH₄ ⁺, indicating that one bismuth-based compound may be innovatively used in both zinc-ion and ammonium-ion batteries (ZIBs and AIBs). Herein, we successfully design a poly(3,4-ethylenedioxythiophene) (PEDOT) coated and embedded Bi₂Te₃ (Bi₂Te₃@PEDOT). Theoretical calculations and experimental studies demonstrate that the PEDOT coating and its intercalation into the interlayer enhance the structural stability of Bi₂Te₃ and significantly improve the storage capacities for Zn²⁺ and NH₄ ⁺. The PEDOT intercalation results in an increased interlayer spacing and a charge redistribution in the interlayer, facilitating charge transfer. Additionally, the insertion-type mechanism of Zn²⁺ and NH₄ ⁺ in Bi₂Te₃@PEDOT is revealed through ex situ tests. The optimized electrode (5 mg cm^-2) exhibits high discharge capacities of 385 mA h g^-1 in ZIBs and 235 mA h g^-1 in AIBs at 0.2 A g^-1 and long-term cycle stability. Bi₂Te₃@PEDOT performs robustly even at a high mass loading of 10 mg cm^-2. Bi₂Te₃@PEDOT//MnO₂ (ZIBs) and Bi₂Te₃@PEDOT//ZnMn₂O₄ (AIBs) full cells offer high reversible capacities. This work provides a reference for designing bifunctional energy storage materials.