Investigation of the microstructure on the nanoporous carbon based capacitive performance

Abstract

Abstract Porous carbon has been widely used as electrode material in supercapacitors because of its many advantages. However, its capacitive performance and energy density still remains lower than desired due to the imperfect microstructure of electrode materials. In this regard, single Al-based metal-organic framework (Al-MOF) crystals were selectively sintered together at high temperature, resulting in the formation of an interconnect nanoporous carbon structure (NPC-950), which exhibits high specific surface area with a co-existence of micro- and mesopores as well as high electronic conductivity. Because of the unique structure, the NPC-950 sample exhibited excellent capacitance performances in both aqueous and organic electrolyte solution. In sharp contrast, the nanoporous carbon derived from Al-MOF single crystals without the interconnect structure shows much lower capacitive performance compared with NPC-950. It is revealed that the interconnect-structure mainly contributes to the enhanced capacitive performance by fast mass transportation and electron transport within the porous carbon network. Furthermore, three organic electrolyte solutions were used to investigate the influence of ionic liquid, pore structure and the solvent on the capacitive performance. It is found that NPC-950 can achieve the highest capacitance in BMIMBF4 electrolyte due to the suitable ion size as well as proper solvent.