Zeolite-templated nanoporous carbon for high-performance supercapacitors

Hierarchical porous carbon prepared with calcium-containing nanocrystalline beta zeolite as the template and ethylene as the carbon source at a relatively low carbonization temperature (600 degrees C) displayed excellent electrocapacitive properties. The presence of both micro/mesopores and surface oxygencontaining groups on the ordered porous structure, along with a high specific surface area (2280 m(2) g(-1)) and pore volume (1.95 cm(3) g(-1) ) coupled with good wettability towards the electrolyte enabled the carbon to perform well as a supercapacitor electrode. This carbon electrode achieved a specific capacitance of 250 F g(-1) at a current density of 1 A g(-1) with 1 M H2SO4 as the aqueous electrolyte measured in a three-electrode system. A symmetric capacitor fabricated with the carbon as both electrodes exhibited a specific capacitance of 161 F g(-1 )at a current density of 1 A g(-1), and an excellent cycling stability. After being cycled 17 000 times and shelved for another two months, the electrode exhibited a specific capacitance of 246 F g(-1) at 1 Ag-1, 153% of the initial capacitance, and still maintained an excellent cycle stability. Besides, an all-solid-state supercapacitor cell fabricated with this carbon as both electrodes and polyvinyl alcohol/H2SO4 gel as the electrolyte displayed an areal specific capacitance of 413 mF cm(-2) at a current density of 0.25 mA cm(-2).