Nanocarbon Materials of Plant Origin for Supercapacitors

For the development of supercapacitors, electrode materials with an enlarged active surface are required. This report deals with the technology for obtaining porous carbon materials (PCMs) from various types of organic matter of plant origin. The parameters of PCM depending on the modes of carbonization and activation, and the effect of the chemical modification of the source precursor were studied. Carbonization was carried out by the pyrolysis from the "pure" and pre-modified raw materials, and activation was carriedout by thermo-chemical methods in various activators. The dependence of the characteristics on the pyrolysis temperature and the time of heating has been found. Modification of the raw material in the acid medium promotes the growth of the PCM capacity, and the best activator is potassium hydroxide. The porosity of PCM has been studied using nitrogen sorption. The value of the specific surface of the pores, the total volume and their high homogeneity are at the level of the best world analogues. The average pore radius is of 0.7-2.2 nm. On the basis of the obtained nanocarbon, a disk supercapacitor “2325” with an aqueous alkaline solution (30 % KOH) was developed. Material of the electrodes was made by pyrolysis of corn rutile and chemically activated in the medium of KOH. The capacity of 11-15 F, internal resistance of 0.3-0.7 Ohm, Coulomb efficiency of 98-99.5 %, initial power up to 3.5 W and energy up to 5.5 J were obtained at 1 V voltage in the element.