Fe-Based Anode Materials for Asymmetric Supercapacitors

This chapter addresses the cutting edge of supercapacitors, focusing on Fe-based pseudocapacitive materials (Fe2O3, Fe3O4, FeOOH, FeS2, etc.), which are currently the most promising anode materials for asymmetric supercapacitors. However, these materials suffer from the intrinsic drawbacks of low utilization efficiency and poor capacitance retention due to limited charge transports and large strain/stress during the charge storage process. In order to settle these drawbacks, substantial research efforts have been devoted to constructing nanostructures, porous structures, and heterostructures, which can be realized by the rational design of synthesis procedures. Herein, charge storage mechanisms are discussed, synthesis methods are highlighted, effects of doping and heterostructures are elucidated, recently developed asymmetric supercapacitors in both aqueous and solid-state forms are summarized, and an outlook on the improvement of specific energy is provided.