Investigation of Device Dimensions on Electric Double Layer Microsupercapacitor Performance and Operating Mechanism

Abstract

Electric Double Layer Capacitor (EDLC) holds the highest share of commercial supercapacitor market. However, it has been proven that current Helmholtz, Gouy-Chapman and Stern models do not provide comprehensive explanation for energy storage mechanism in EDLC. In this work the effects of interdigitated EDLC design on capacitance of flexible laser scribed interdigitated microsupercapacitor (LSG-MSC) are studied. Three design parameters are tested, (1) current collector-electrode interaction, (2) electrode aperture, and (3) distance between parallel electrodes. Noticeable change was observed in the total capacitance upon change in LSG-MSC design which was analyzed in detail using cyclic voltammetry, electrochemical impedance spectroscopy and electrostatic simulation using COMSOL Multiphysics. It was found that in addition to electric double layer capacitance, an electric field was generated between electrodes and between electrode and current collector which led to small electrostatic capacitance between them. This electric field was also found to cause disturbance in double layer formation at the electrode thus causing change in the overall capacitance as the design parameters were varied.