Carbon nanofiber-coated MnO composite as high-performance cathode material for aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (AZIBs) are a promising next-generation energy storage technology owing to their intrinsic safety, low cost, and sustainability. However, typical AZIB cathode materials, such as manganese oxides, have poor conductivity and structural stability, leading to low energy storage capacity and poor cycle life, thus, limiting practical applications. In this work, manganese oxide coated with carbon nanofibers (MnO@CNFs) was developed as an AZIB cathode. A facile synthetic strategy based on electrospinning was employed to obtain these composites, which showed dramatically improved electrochemical activity and structural stability. The MnO@CNFs cathode, exhibited a high specific capacity (430 mAh g−1 at 0.1 A g−1), excellent rate capability, and long cycling durability (81% retained after 2500 cycles at 1.0 A g−1). The electrochemical reaction mechanism with complex phase evolution was explored by ex-situ characterization after charging/discharging, indicating the high reversibility and good cycling stability of the co-insertion process of H+/Zn2+ in the MnO@CNFs electrode. This study provides a facile and versatile strategy for fabricating high-performance Mn-based cathode materials and offers a deeper understanding of the energy storage mechanism in AZIBs.