9. Characteristics of Electrode Materials for Supercapacitors

Device performance is based on the individual properties of the materials and performance of the components in the working environments. For example, the fabrication of high-performance supercapacitors and the electrode material should have a high specific surface area and high electrical conductivity along electrical and thermal stability. For different charge storage mechanisms in supercapacitors like electrical double-layer capacitors, pseudocapacitors and hybrid capacitors, and different types of electrode materials are proposed. Electrode materials of a supercapacitor decide the storage of charge in the device and thereby the capacitance of the final device. The effective surface area including electrical conductivity remains the parameter of importance to produce high capacitance. Carbon materials are proposed as the electrode material by storage of the charge at the surface of the material via electrical double-layer capacitance. High surface area, appropriate pore size, pore size distribution and the presence of functional groups complement the capacitance of the device. Some commonly used carbon-based materials of interest are graphite, graphene, carbon nanotube, activated carbon, etc. Other materials of importance remain metal oxides, conducting polymers, metal–organic frameworks, MXenes, black phosphorus, metal nitrides, etc. This chapter provides a short yet comprehensive overview of the characteristics of suitable electrode material for supercapacitor devices. Activated carbon, carbon nanotubes, graphene, polyaniline (PANI), polypyrrole (PPY) and polythiophene (PTH) are examples of some of the suitable electrode materials.