ACETYLENE BLACK POLY(VINYLIDENE FLUORIDE) GEL ELECTROLYTE COMPOSITE ELECTRODE FOR AN ELECTRIC DOUBLE-LAYER CAPACITOR

A composite electrode with carbon powder and poly(vinylidene fluoride) (PVdF) gel electrolyte is prepared and investigated as an electrode f or an electric double-layer capacitor (EDLC). PVdF-based gel, with a m ixture of ethylene carbonate (EC) and propylene carbonate (PC) as plas ticizer, and tetraethylammonium tetrafluoroborate (TEABF(4)) is used a s the electrolyte of the EDLC. The composite electrode shows a higher specific capacitance and lower ion-diffusion resistance inside the ele ctrode than those studied previously with carbon electrodes prepared w ith PVdF binder only. The highest specific capacitance, 4.1 F g(-1), i s achieved for an acetylene black (AB)/PVdF gel composite electrode wi th a PVdF content of 30 wt.%. This is because the electrode has the be st contact stale between AB and PVdF gel electrolyte. Finally, the per formance of an EDLC with AB/PVdF gel composite electrodes is evaluated and an excellent cyclability over 10(5) cycles with similar to 100% c oulombic efficiency is achieved during charge-discharge between 1.0 an d 2.0 V at 1.66 mA cm(-2). (C) 1998 Elsevier Science S.A. All rights r eserved.