Abstract
Carbonaceous materials are commonly used to fabricate electrodes for electric double-layer capacitors (EDLCs) or supercapacitors. The internal resistance of the carbon electrode comes from the carbon material itself, carbon particle-particle contact, and carbon-current collector contact. The high internal resistance of the carbon electrode can decrease capacitor energy and power performance, and reduce the lifetime of the capacitor. In this report, the sources of carbon based EDLC internal resistance were explored using electrochemical impedance spectroscopy (EIS). A generalized equivalent circuit model was coupled with the EIS for the analyses. The EDLC cells were made from symmetric carbon/Al electrodes and operated in organic electrolyte. The analysis results showed the effects of the current collector, amount of polymer binder Poly(vinylidene fluoride) (PVDF) and carbon particle sizes on the internal resistance of the electrode.