Alternative Multivalent Metal Elements for Aqueous Hybrid Supercapacitors

Abstract

The growing importance of sustainable and clean energy sources is a direct consequence of the increasing scarcity of non-renewable resources and the necessity for energy storage solutions that are safe, efficient, and adaptable. Aqueous hybrid supercapacitors (AHSCs) have garnered attention due to their advantageous characteristics, including low cost, safety, reliability, and high cyclic stability. Here, this review provides a brief overview of the energy storage mechanisms of double electric layer capacitors (EDLCs), pseudocapacitors, and hybrid supercapacitors (HSCs), which combine the features of both of these types of capacitors. The progress made in recent years in research on AHSCs using multivalent metal cations, including manganese, zinc, and chromium, is highlighted. Additionally, some examples of AHSCs assembled with the participation of metal ions are summarized based on the metal activity series. Furthermore, the potential use of other multivalent metals, including iron, cobalt, nickel, and copper, in AHSCs electrodes was explored, as well as the current status of aqueous ammonium-ionized HSCs, with a focus on their respective advantages and challenges. Finally, this review proposes future research directions to further advance this field.