Preparation of Porous Carbons Pyrolyzed by Casein and Their Supercapacitor Performances

Many porous carbon materials derived from biomass were high performance electrode materials for supercapacitor. The natural macromolecule of casein was utilized as the precursor of carbon materials. It was mixed with phytic acid in the acid solution, thus forming the acid-base cross-linking between them. The mixtures were pre-carbonized at low temperature and further activated by KOH at high temperature, achieving porous carbon materials. These carbon materials exhibited a high specific surface area of up to 3 567 m²/g and were considered as an excellent electrode material for supercapacitors. Their electrochemical properties were characterized by both three-electrode and two-electrode systems in alkaline electrolyte. In the three-electrode system, the specific capacitance was as high as 411 F/g at 1 A/g. In the two-electrode system, the specific capacitance was up to 235 F/g at 1 A/g and remained to be 231 F/g after 8 000 charge-discharge cycles at 5 A/g. Results revealed that these porous carbon materials displayed high capacitances and outstanding cycling stabilities. These carbon materials exhibited better performance for supercapacitor in comparison with most carbon materials pyrolyzed by natural macromolecules. Moreover, this facile and efficient route could be used for the fabrication of high performance porous carbon materials.