Iron-Based Supercapacitor Electrodes: Advances and Challenges

Supercapacitors (SCs) have great promise as the state-of-the-art power source in portable electronics and hybrid vehicles. The performance of SCs is largely determined by the properties of the electrode material, and numerous efforts have been devoted to the explorations of novel electrode materials. Recently, iron-based materials, including Fe2O3, Fe3O4, FeOOH, FeOx, CoFe2O4, and MnFe2O4, have received considerable attention as very promising electrode materials for SCs due to their high theoretical specific capacitances, natural abundance, low cost, and non-toxicity. However, most of these Fe-based SC electrodes suffer from poor conductivity and/or electrochemical instability, which seriously impede their implementation as high-performance electrodes for SCs. To settle these issues, substantial efforts have been made in improving their conductivity and cycling stability, and great processes have been achieved. Here, recent research advances in the rational design and synthesis of diverse Fe-based nanostructured electrodes and their capacitive performance for SCs are presented. Besides, challenges and prospects of Febased materials as advanced negative electrodes for SCs are also discussed.