Contribution of mesopores in MgO-templated mesoporous carbons to capacitance in non-aqueous electrolytes

• The present work reports contribution of mesopores to capacitance in non-aqueous electrolytes.
• MgO-templated mesoporous carbons exhibited excellent rate performances of electric double layer capacitors.
• The diffusion resistance of ions was reduced by the presence of the mesopores.
• Annealing of the carbon precursors above 900 °C provide a sufficiently low charge transfer resistance for high-rate operation.

MgO-templated mesoporous carbons were fabricated by annealing trimagnesium dicitrate nonahydrate at various temperatures from 700 to 1000 °C with subsequent acid leaching of MgO. The obtained carbons contained a large amount of mesopores. Performances of electric double-layer capacitors using these carbons were examined for propylene carbonate electrolyte containing 1 M tetraethylammonium tetrafluoroborate. The mesoporous carbons synthesized at higher temperatures showed better rate capabilities. AC impedance measurements indicated that high-temperature annealing of the carbon precursors and the presence of mesopores were important for high rate performance. In addition, the contribution of mesopores to capacitance was more significant at higher current densities of 30 A g−1.