Noncorrosive separator materials for electric double layer capacitor

The paper evaluates noncorrosive and inexpensive materials, namely polypropylene sheet, fiberglass, and glass wool, as potential separator materials for electric double‐layer capacitor ( EDLC ) application. Using these materials as separators and the same activated carbon electrodes, properties of two‐electrode capacitors filled with aqueous sulfuric acid (H 2 SO 4 ) were investigated by cyclic voltammetry ( CV ) as well as galvanostatic and electrochemical impedance spectroscopy ( EIS ) measurements. Performance comparison of the tested capacitors with an identical capacitor with conventional cellulose separator was also carried out. As a benchmark, the noncorrosive‐separator‐based capacitors demonstrate comparable power and energy densities to those of a cellulose separator, with the highest specific capacitance of 131 F/g and lowest equivalent series resistance of 13 Ω for the glass wool separator. Application of such noncorrosive separators may realize the utilization of high‐concentration aqueous electrolytes, leading to higher rating EDLCs at lower cost compared to organic‐solution‐based capacitors. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.