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.