NEW ELECTRIC DOUBLE-LAYER CAPACITORS USING POLYMER SOLID ELECTROLYTES CONTAINING TETRAALKYLAMMONIUM SALTS

Solid electrolytes consisting of complexes of poly(ethylene oxide)-grafted poly(methyl)-methacrylate (PEO-PMMA) and tetraalkylammonium salts (tetrabutylammonium perchlorate, tetraethylammonium perchlorate, and tetraethylammonium tetrafluoroborate) have been investigated for electric double-layer capacitors. The composites obtained showed high ionic conductivity (about 10(-4) S cm-1 at 298 K). When the PEO-PMMA-tetraethylammonium tetrafluoroborate composites were used in solid-state electric double-layer capacitors with activated carbon-fiber cloths as polarizable electrodes, the capacitors showed charge/discharge behavior with large values of capacitance. The maximum capacitance was ca. 0.57 F/cm2 (of each electrode), which was comparable to that of usual liquid-type electric double-layer capacitors.