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

Abstract

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.