A symmetric carbon/carbon supercapacitor operating at 1.6 V by using a neutral aqueous solution

A high voltage symmetric carbon/carbon supercapacitor was built using a Na2SO4 aqueous solution. This system exhibits an excellent cycle life during thousands of cycles up to voltage values as high as 1.6 V. Three-electrode investigations show a particularly high potential window, ΔE = 2 V, for the considered activated carbon in Na2SO4. However, in a two-electrode cell, when the voltage is higher than 1.6 V, the potential of the positive electrode is beyond the oxidation potential of water, and AC is oxidized. These results demonstrate the potentialities of Na2SO4 for developing high energy density systems.