| abstract |
An ultracapacitor (10) comprises two solid, nonporous current collectors (22, 24), two porous electrodes (14, 16) separating the collectors (22, 24), a porous separator (18) between the electrodes (14, 16) and an electrolyte (20) occupying the pores in the electrodes (14, 16) and separator (18). The porous separator (18) layer comprises an amorphous fumed silica layer coated onto at least one of the electrodes (14, 16). |