Aqueous-based, high-density nanoporous carbon xerogels with high specific surface area for supercapacitors

Electrode materials with high density for assembling supercapacitors with high volumetric capacitance are urgently needed. Herein, nanoporous carbon xerogels (NPCXs) are synthesized from aqueous-based resorcinol–formaldehyde xerogels which are dried at ambient condition without the organic solvent exchange. NPCXs with a high density (0.719 g cm−3) and high specific surface area (2082 m2 g−1) are prepared via the pyrolysis and CO2 activation. By increasing the number of carbon nano particles per unit area, more micropores can be formed followed by CO2 activation. The pore size is mainly distributed in the range of 0.6 and 3.0 nm, which plays a favorable role in ion transfer between electrode and electrolyte in supercapacitors. The as fabricated supercapacitor with NPCXs exhibits a high specific capacitance of 202 F cm−3 at 10 mV s−1, and a high energy density of 7014 Wh m−3. Moreover, the electrode also shows an excellent cycle stability with a capacitance retention of 95% after 5000 cycles at a current density of 10 A g−1.