Supercapacitor devices are well-known as their fast charge storage kinetics by the electric double-layer capacitance (EDLC) or EDLC-like mechanisms at the electrode/electrolyte interfaces. So far, research groups worldwide have been mostly worked on the electrodes consist of carbon-based (e.g. porous carbon, graphene, curved graphene nanosheets, graphene nanoribbons, carbide-derived carbon and etc.), two dimensional layered (e.g. Ti₃C₂T_x MXene) and transition metal oxide/sulfides/phosphates (e.g. MnO₂, Co₃O₄ and etc.) materials. The former stores charge by the adsorption of electrolyte ions onto the surface of the electrode materials providing high power density. The two latter ones store charge by fast redox reactions presenting an intrinsic (such as MnO₂) or extrinsic (such as LiCoO₂ thin films) pseudocapacitive properties providing high energy density.

More useful information on this subject can be found in informative published papers like:

1- Noori et al. Towards establishing standard performance metrics for batteries, supercapacitors and beyond, Chemical Society Reviews, 2019.

2- Bu et al. Recent developments of advanced micro-supercapacitors: design, fabrication and applications. npj Flexible Electronics, 2020.

3- Wang et al. Recent Progress in Micro-Supercapacitor Design, Integration, and Functionalization. Small Methods, 2018.

4- Gogotsi et al. Where Do Batteries End and Supercapacitors Begin? Science, 2014.

5- Brousse et al. To Be or Not To Be Pseudocapacitive? journal of the Electrochemical Society, 2015.