A Bi2Te3/Te heterojunction cathode with an insertion/conversion dual-mechanism for high-capacity aqueous zinc-ion batteries.

Abstract

The topological insulator Bi2Te3 has attracted significant attention in zinc-ion batteries (ZIBs) due to its unique quantum effects and high theoretical capacity. However, its practical application is hindered by the severe volume expansion during Zn2+ insertion/extraction and sluggish reaction kinetics. Herein, we report the rational construction of a Bi2Te3/Te heterostructure via in situ integration of conversion-type active tellurium, serving as an advanced dual-electric-field in situ induced insertion/conversion dual-mechanism heterointerface cathode for aqueous zinc-ion batteries. Experimental characterization and first-principles density functional theory (DFT) calculations reveal that the heterojunction induces a semiconductor-to-metal transition, resulting in significantly enhanced intrinsic conductivity and accelerated Zn2+/H+ adsorption. Consequently, both the electrochemical kinetics and structural stability are markedly improved. The energy storage mechanism involves not only the synergistic insertion of Zn2+/H+ but also an additional conversion reaction between Te0 and Te2- species. Owing to these advantages, the Bi2Te3/Te cathode delivers a high specific capacity of 294 mAh g-1 at 2 A g-1, excellent rate capability, and reliable cycling stability. Moreover, the assembled flexible quasi-solid-state battery maintains stable electrochemical performance and mechanical integrity under repeated bending conditions. This work provides valuable insights into the design of high-performance heterostructured cathodes for aqueous ZIBs.