Activated carbon with high capacitance prepared by NaOH activation for supercapacitors

Activated carbons with high volumetric capacitance are prepared from apricot shell by optimizing the carbonization temperature prior to NaOH activation to balance the porosity and density. The carbonization temperature has a marked effect on both the pore structure and the electrochemical performances of the activated carbons. As the carbonization temperature increases, the specific surface area and gravimetric capacitance of the carbons decrease, while the apparent electrode density increases. Moderate carbonization at 500 °C results in not only high gravimetric capacitance (339 F g−1) but also high apparent electrode density (0.504 g cm−3), and hence a highest volumetric capacitance of 171 F cm−3 in 6 mol L−1 KOH aqueous electrolyte is obtained. The activated carbons also show good rate capability.