In situ synthesis of Bi3+-doped δ-MnO2 cathode to enhance the cycle stability for aqueous zinc-ion batteries.

Bi³⁺-doped δ-MnO₂ materials (BMX, X = 5, 10, 15) with long cycle life were obtained by an in situ electrochemical reaction using δ-MnO₂ and Bi₂O₃ mixture as raw materials. According to the material characterization and electrochemical performance test, it indicates that the bismuth is evenly incorporated into δ-MnO₂. Among these obtained materials, BM10 exhibits the best performance. The specific capacity of the BM10 cathode is maintained at 108 mAh g⁻¹ after 5000 cycles at a current density of 3 A g⁻¹ and remains at 70 mAh g⁻¹ after 9000 cycles without attenuation at a high current density of 10 A g⁻¹. The Bi³⁺ modification mechanism is also revealed by the electrochemical kinetic and chemical analyses, which can effectively stabilize the layered structure of δ-MnO₂, increase the diffusion rate of Zn²⁺ and H⁺, and inhibit the dissolution of Mn²⁺ formed by the disproportionation reaction of Mn³⁺. The preparation process of manganese-based materials with excellent performance is easy to handle and has large-scale production and application prospects. [ABSTRACT FROM AUTHOR]