Preparation of Porous Carbons Using NaOH, K2CO3, Na2CO3 and Na2S2O3 Activating Agents and Their Supercapacitor Application: A Comparative Study

The sustainable energy development of green carbon precursors and inexpensive activating agents has gained great attention with respect to the manufacture of high-performance electrode materials for supercapacitors. Though the most investigated activation agents such as ZnCl2 and KOH provide porous carbon possessing the high surface area and large charge storage capacity, those activation agents suffer from the use of high dosage utilization and poor carbon production yield. Herein, we report an alternative preparation method for porous carbons using NaOH, K2CO3, Na2CO3 and Na2S2O3 as activating agents, respectively. Activating performances of four pore-forming agents were compared in terms of textural, morphological and electrochemical performance. It was found that the NaOH-activated electrode material (C-NaOH) exhibited a high specific capacitance of 199 F g(-1) at a current density of 0.5 A g(-1) thanks to its large surface area along with large pore volume. In the two-electrode system, the symmetric SC assembled by C-NaOH electrodes delivered an energy density of 4.7 Wh/kg at a power density of 127 W/kg and maintained 3.9 Wh/kg at a power density of 1560 W/kg. Another outcome of this study was that the Na2S2O3-assisted activating agent could introduce heteroatom into the carbon framework, which contributes to pseudocapacitance behavior of electrodes. Overall, the alternative activating strategy could provide a high-performance carbon electrode and may offer a pathway for an advanced energy storage technology.