Architecturing carbon nanotube-based flexible solid state supercapacitor

We report preliminary investigation of an all-solid-state electrochemical double layer capacitor using single wall carbon nanotube electrodes and polymer electrolyte. Binder free single walled carbon nanotubes were self-assembled to form a highly dense 20 μm thick carbon nanotube electrode to be used in electrochemical capacitors. Fabrication of symmetric nanotube capacitors using these electrodes and highly ionically conducting polyvinyl alcohol based hydrogel membranes soaked in aqueous sulfuric acid resulted in a capacitor with power density as high as 1040 KW/kg based on mass of both the electrodes. The time constant of the assembled capacitor was ∼ 15 ms and was dependent on the concentration of sulfuric acid. The capacitors showed no degradation in performance even after 10,000 cycles. The charge/discharge measurements at temperatures from 20°C to 80°C showed a linear increase with increasing temperature. However, at temperatures above 80°C, we observed a decrease in the specific capacitance.