A review of charge storage in porous carbon-based supercapacitors

Porous carbon-based electrode materials have been widely used in supercapacitors (SCs) because of their good physicochemical stability, high specific surface area, adjustable pore structure, and excellent electrical conductivity. The factors influencing their SC performance are analyzed, which include specific surface area, pore structure, surface heteroatoms, structural defects and electrode structure. The high surface area accessible to ions provides abundant active sites for their storage, while a suitable pore structure is important for the accommodation and diffusion of ions, thereby influencing the specific capacitance and rate performance of the electrodes. An appropriate pore size with a narrow distribution is required to increase the volumetric energy density while mesopores are favorable for ion transport, so a good balance between micro and mesopore volumes is important to improve both the energy and power densities of the SCs. Structural defects, surface heteroatoms and a rational electrode structural design all play significant roles in the capacitance performance.