Enhanced electrochemical performance for EDLC using ordered mesoporous carbons (CMK-3 and CMK-8): Role of mesopores and mesopore structures

Abstract

Non-aqueous electrical double-layer capacitors (EDLCs) with high energy density and long cycle life are the key to meet future energy demands. The performance of such high-energy supercapacitors greatly depends on the textural properties of the porous carbon electrode. Ordered mesoporous carbon materials are always the prominent electrodes for capacitor applications and the roles of pore size and pore structure need to be investigated in a non-aqueous capacitor system to achieve high performance. Herein, a series of well-ordered mesoporous carbon materials (OMCs) with high specific surface areas and high pore volumes are synthesized utilizing mesoporous silica (SBA-15 and KIT-6) templates at different carbonization temperatures and studied for EDLCs with non-aqueous electrolytes. The performance of EDLCs greatly depends on the mesopore structure and mesoporous surface area, which is evident from the electrochemical performance. In particular, CMK-3 (prepared using SBA-15) shows a higher specific capacitance than CMK-8 (prepared using KIT-6), which may come from the long straight channels of CMK-3 leading to a lower internal resistance and larger number of ion-diffusion pathways. The mesopores provide not only larger pores for fast electrolyte ion transport but also a high surface area and high pore volume for ion storage during the charge–discharge processes. Increasing the carbonization temperature from 600 to 900 °C increases the mesoporous surface area, resulting in enhanced specific capacitance.