The energy and power densities of electric double layer capacitor were calculated in order to estimate the possibility of its application to the pulse power supply for an electric vehicle. The model capacitor is composed of a stack of cell unit simply assembled with bipolar module with the physical and electrochemical properties of aqueous or organic electrolytes. The calculation was done with the variations of cell numbers and the roughness of electrode where the roughness is assumed to be the ratio of real surface area to flat surface area. The resultant energy densities of models showed that the capacitor using organic electrolyte had a merit of high energy density caused by the wide potential window of organic electrolyte. The results of power density under the 30 s full discharge suggested that aqueous electrolyte gave high power density to the capacitor while organic electrolyte lower power output because of the high resistance of the electrolyte solution. Moreover, the power densities of capacitors with organic and aqueous electrolytes showed maximum and sharp decline with an increase in cell stacked number due to the increase of capacitor resistance. From the results, it is suggested that the development of new components and cell construction should be demanded for capacitor with organic electrolyte.
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