Effect of pore structure and doping species on charge storage mechanisms in porous carbon-based supercapacitors

Porous carbon materials are an attractive choice as electrode materials for supercapacitors due to their large specific surface area, high conductivity, stable chemical properties and low cost. In recent years, the electrochemical performance of porous carbon-based supercapacitors has gained considerable attention and has been greatly improved via the rational design of morphology/porous structure and surface properties. However, for these porous carbon electrodes, there remains a limited understanding of practical ion dynamics, charge storage mechanisms and their influence on the electrochemical performance. Therefore, an in-depth fundamental understanding of the charge storage mechanisms, transport pathways of electrons/ions and the electrochemically active sites is extremely important for further building efficient supercapacitors. Existing reviews in the literature mainly focus on the preparation and properties of porous carbon. Herein, we specifically summarize the state-of-the-art progress, from in situ characterization experiments and theoretical calculations to understand the ion/charge storage in porous carbon electrodes of supercapacitors, and further discuss the structure-activity relationships between doping species and electrochemical performances. Furthermore, the challenges and future development associated with supercapacitors in practical applications are included.