Enhancing gravimetric and volumetric capacitance in supercapacitors with nanostructured partially graphitic activated carbon

The volumetric and gravimetric capacitance of supercapacitors are primarily influenced by the specific surface area and porosity required for the formation of electric double layers in the electrode material, and these capacitance are known to have a trade-off relationship. To address this issue, additional capacitance enhancement mechanisms are needed not only at the electrode material surface but also within the limited mass and volume, which can be achieved through structural improvements of the material. In this study, we produce partially graphitic activated carbon with low specific surface area but nano-sized crystalline regions from petroleum pitch, a soft carbon precursor. This approach allows for improvements in gravimetric capacitance. The resulting activated carbon with a specific surface area of 1122 m² g⁻¹ exhibits volumetric specific capacitance of 27.9 F cc⁻¹ and gravimetric specific capacitance of 38 F g⁻¹ in an organic electrolyte, indicating a new direction for electrode materials in supercapacitors.