Preparation of novel 3D hierarchical porous carbon membrane as flexible free-standing electrode for supercapacitors

A flexible 3D hierarchical porous carbon membrane was simply fabricated for supercapacitor electrode by using polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF) as raw material and polyvinyl pyrrolidone (PVP) as additive via nonsolvent induced phase separation (NIPS) and carbonization. Experimental results show that the as-prepared carbon membranes display typical spongy skeleton structure and excellent flexibility. The specific surface area, micropore, mesopore, and total pore volume of the carbonmembranes are increased with the increase of PVDF content. The prepared carbon membranes show large specific surface area (491 m(2) g(-1)) and 3D hierarchical porous structure. As free-standing electrode for supercapacitors, the carbon membranes exhibit a high specific capacitance of 265 F g(-1) in three-electrode system and 212 F g(-1) in two-electrode system at 0.05 A g(-1) in 6 M KOH aqueous electrolyte. Such outstanding capacitive performance is due to the hierarchical porous structure and ameliorated surface chemical functional groups, offering a favorable pathway for ion penetration, considerable surface for accumulation of electrolyte ions and improving the surface accessibility for electrolyte ions. It is believed that the simple and effective approach to hierarchical porous carbon membranes have good application prospect in production of freestanding electrode of supercapacitors.