Flexible Single-wall Carbon Nanotube Membrane Symmetric Aqueous Double Layer Electrochemical Capacitor*

We present preliminary results on an aqueous symmetric double layer electrochemical capacitor (EDLC) constructed with flexible binder-free single wall carbon (SWCNTs) membrane as electrodes. The capacitors were cycled from 0 to 1V @ 10 A/g for 10,000 cycles with 99.9{\%} coulombic efficiency and 94{\%} energy efficiency, and 100{\%} depth of discharge. The power performance of the aqueous symmetric SWCNTs membrane capacitor is almost 100 --1000 times better than commercial non-aqueous EDLC capacitors.