Research progress in transition metal chalcogenide based anodes for K-ion hybrid capacitor applications: a mini-review

Metal ion capacitors have gained a lot of interest as a new kind of capacitor-battery hybrid energy storage system because of their high power density while maintaining energy density and a long lifetime. Potassium ion hybrid capacitors (PIHCs) have been suggested as possible alternatives to lithium-ion/sodium-ion capacitors because of the plentiful potassium supplies, and their lower standard electrode potential and low cost. However, due to the large radius of the potassium ion, PIHCs also face unsatisfactory reaction kinetics, low energy density, and short lifespan. Recently, transition metal chalcogenide (TMC)-based materials with distinctive structures and fascinating characteristics have been considered an emerging candidate for PIHCs, owing to their unique physical and chemical properties. This mini-review mainly focuses on the recent research progress on TMC-based materials for the PIHC applications summarized. Finally, the existing challenges and perspectives are given to improve further and construct advanced TMC-based electrode materials.