Easy fabrication and high electrochemical capacitive performance of hierarchical porous carbon by a method combining liquid-liquid phase separation and pyrolysis process

A hierarchical porous carbon membrane was designed and prepared through a method combining liquid-liquid phase separation and then pyrolysis process using polyacrylonitrile (PAN) as precursor. The results of scan electron microscopy, transmission electron microscope and Brunauer-Emmett-Teller characterization reveal that the 3D nanoscaled architecture with hierarchical porous structure was achieved, which not only provide a continuous electron pathway to ensure good electrical contact, but also facilitate ion transport by shortening diffusion pathways. The effect of PAN concentration in casting solution on structure feature of carbon membrane was also studied, indicating that the membrane thickness with different porous structure can be mediated by PAN concentration. As the electrode material for supercapacitor, a high specific capacitance of 277.0 F g−1 was attained at a current density of 5 mA cm−2 and long cycle life of 90.0% capacity retention was obtained after 2000 charge-discharge cycles in 2 mol L−1 KOH solution.