In situ synthesis of Bi 3+ -doped δ-MnO 2 cathode to enhance the cycle stability for aqueous zinc-ion batteries

Bi 3 + -doped δ-MnO 2 materials (BMX, X = 5, 10, 15) with long cycle life were obtained by an in situ electrochemical reaction using δ-MnO 2 and Bi 2 O 3 mixture as raw materials. According to the material characterization and electrochemical performance test, it indicates that the bismuth is evenly incorporated into δ-MnO 2 . 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 Bi 3+ modification mechanism is also revealed by the electrochemical kinetic and chemical analyses, which can effectively stabilize the layered structure of δ-MnO 2 , increase the diffusion rate of Zn 2+ and H + , and inhibit the dissolution of Mn 2+ formed by the disproportionation reaction of Mn 3+ . The preparation process of manganese-based materials with excellent performance is easy to handle and has large-scale production and application prospects.