N, S-Codoped Activated Carbon Material with Ultra-High Surface Area for High-Performance Supercapacitors

The recycling of macromolecular biowastes has been a problem for the agriculture industry. In this study, a novel N, S-codoped activated carbon material with an ultrahigh specific area was produced for the application of a supercapacitor electrode, using tobacco stalk biowastes as the carbon source, KOH as the activating agents and thiourea as the doping agent. Tobacco stalk is mainly composed of cellulose, but also contains many small molecules and inorganic salts. KOH activation resulted in many mesopores, giving the tobacco stem-activated carbon a large specific surface area and double-layer capacitance. The specific surface area of the samples reached up to 3733 m²·g^-1, while the maximum specific capacitance of the samples obtained was up to 281.3 F·g^-1 in the 3-electrode tests (1 A·g^-1). The doping of N and S elements raised the specific capacitance significantly, which could be increased to a value as high as 422.5 F·g^-1 at a current density of 1 A·g^-1 in the 3-electrode tests, but N, S-codoping also led to instability. The results of this article prove that tobacco stalks could be efficiently reused in the field of supercapacitors.