Metal–Organic Frameworks-Derived Porous Fe-Doped MnO/Bi/C Composites with Dual Redox Reactions for High-Performance Aqueous Zinc-Ion Batteries

Constructing dual redox-active sites is capable of enhancing the electrochemical performance of materials. By introducing the element Bi to enable dual redox-active sites and doping Fe to create additional ion insertion channels, the Fe–MnO/Bi/C composites, which expose more active sites and possess higher ion transport rates, were fabricated. The Fe–MnO/Bi/C cathode demonstrates superior capacity and cycling stability in comparison with other materials. Furthermore, the addition of KI to the electrolyte promotes the conversion reaction of Bi/Bi3+ and also introduces the I–/I2 conversion reaction. As a result, the Fe–MnO/Bi/C cathode attains a higher capacity of 354 mA h g–1 at 0.2 A g–1 and maintains a capacity of 98 mA h g–1 after 10,000 cycles at 10 A g–1. Moreover, it exhibits excellent low-temperature performance, retaining a capacity of 143 mAh g–1 after 320 cycles at −10 °C with a current density of 1 A g–1.