Activated carbon materials are prepared from phenolic resin precursors by physical activation to fabricate electrodes for electric double-layer capacitors (EDLCs). Pore size and surface area of the carbon materials are controlled during the synthesizing process and after the carbonization through activation in a CO 2 atmosphere to different levels of burn-off. The resultant carbon materials were evaluated as EDLC electrodes, using electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD) measurements with the organic electrolyte of spiro-(1,1 0 )-bipyrrolidinium tetrafluoroborate in propylene carbonate, SBPBF 4 /PC. The results of the study showed that the capacitance of carbon materials, as well as energy density of the EDLC cells, increased by increasing the level of burn-off (activation). The 46% activated carbon gave a capacitance of $160 F g À1 and an energy density of $35 W h kg À1 , at a current density of 1 mA cm À2 . The long term cycling tests showed high cycling stability of these carbon materials.
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