A composite electrode with carbon powder and poly(vinylidene fluoride) (PVdF) gel electrolyte is prepared and investigated as an electrode for an electric double-layer capacitor (EDLC). PVdF-based gel, with a mixture of ethylene carbonate (EC) and propylene carbonate (PC) as plasticizer, and tetraethylammonium tetrafluoroborate (TEABF4) is used as the electrolyte of the EDLC. The composite electrode shows a higher specific capacitance and lower ion-diffusion resistance inside the electrode than those studied previously with carbon electrodes prepared with PVdF binder only. The highest specific capacitance, 4.1 F g-1, is achieved for an acetylene black (AB)/PVdF gel composite electrode with a PVdF content of 30 wt.%. This is because the electrode has the best contact state between AB and PVdF gel electrolyte. Finally, the performance of an EDLC with AB/PVdF gel composite electrodes is evaluated and an excellent cyclability over 105 cycles with ∼ 100% coulombic efficiency is achieved during charge-discharge between 1.0 and 2.0 V at 1.66 mA cm-2.
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