Mesoporous Carbon Electrodes for Supercapacitor with Sodium ion Exchange Aquivion as Electrolyte membrane

Mesoporous carbons are potential electrode material for energy storage systems owing to their interconnected pore characteristics, high surface area and conductivity. Among them, CMK-3 is a good candidate as materials electrode for supercapacitor and battery due to its ordered porosity, and chemical and mechanical stability.1 Highly ordered mesoporous carbon can be normally achieved by templating with ordered porous silica. SBA-15, the well-known ordered mesoporous silica, is an appropriate template for obtaining high quality interconnected mesoporous carbon compared to other silica templates. The derived carbon (CMK-3) was found to be a true replica of SBA-15 with one dimensional carbon tubes connected by carbon channels. The synthesis process of CMK-3 involved multiple steps such as preparation of SBA-15, impregnation of carbon precursor, followed by pyrolysis and removal of the template.2,3 Alternative strategies are needed to replace this complex and time-consuming standard procedure to make the process commercially feasible. Here, we adopted two methods of synthesis for the silica template: i) standard method of synthesis and ii) ultrasonication assisted synthesis. Rapid condensation of silica precursors occurred during sonication and effectively reduced the time for the synthesis of silica template. Mesoporous carbons with high surface area were obtained through both methods. Symmetric supercapacitors were constructed with these carbons using sodium ion exchange Aquivion membrane as both separator and electrolyte. Both cells exhibited rectangular cyclic voltammograms with the electrical double layer behaviour. Specific capacitances of 55 F/g and 75 F/g were obtained for cells with ultrasonication method derived carbon (USC) and standard method derived carbon (SMC), respectively. Furthermore, hybrid supercapacitors with asymmetric configuration based on manganese oxide and CMK-3 at positive and negative electrodes, respectively were realized and investigated. The best cell exhibits better performance with a specific capacitance of 84 Fg-1. The capacitor undergone 10,000 cycles under conditions of galvanostatic charging and discharge and floating at 1.6 V with a very long-term stability. Self-discharge measurements on the cell showed a very low voltage decay with time after charging the SC for 3 h at 1.6 V.