Relation between Space Charge and Pore Size of Nano Porous Electrode for Super Capacitor

The space charge distribution in electric double layer capacitor (EDLC) for energy storage has been examined by pulsed electro-acoustic (PEA) method since 2002. It is found that the measuremental result can be influenced by the reflection and penetration of the sound wave when the space charge distribution of EDLC is measured by PEA method, because the EDLC has a five layer structure consisting of three materials (aluminum, cellulose, and activated carbon). Then, we calculated reflection wave components that influence on charge density from the acoustic impedance and relative permittivity of the materials. As a result, it has been understood that the changes in the space charge distribution of EDLC and the charge characteristic of the EDLC are almost corresponding. The use of the PEA method can be expected as a method of evaluating the accumulation charge of EDLC by measuring the space charge distribution of it. In this paper, a polarized electrode is made to develop EDLC and a ratio of surface area and average pore diameter of polarized electrode is measured by nitrogen adsorption method at 77K. Also, relation between a ratio of surface area and average pore diameter and space charge distributions of EDLC are discussed.