A Standard-Aligned Framework for Voltage-Dependent Supercapacitor Characterization

Abstract

Supercapacitors, also known as Electric Double-Layer Capacitors (EDLCs), are increasingly used in high power energy storage systems because of their long cycle life, high-power density, and rapid charge–discharge capability. However, inconsistencies in the datasheet specifications, particularly in capacitance and equivalent series resistance (ESR), make accurate modeling and comparison between manufacturers difficult. This work addresses these discrepancies by developing a unified analytical framework that extracts voltage-dependent capacitance parameters directly from IEC 62391-1 and IEC 62576 discharge measurements without modifying the standard procedure. The method derives the parameters $C_{\mathrm{0}}$ and $k$, providing a consistent and physically meaningful representation of the nonlinear capacitance behavior. A total of 78 discharge measurements were performed, comprising 54 tests on 25 F cells from six manufacturers (three DUTs each) and 24 tests on 50 F cells from one manufacturer (eight DUTs), each evaluated across three voltage ranges and three discharge currents. These datasets were used to verify the robustness and applicability of the proposed framework under varying test currents between samples from different manufacturers. Results show that the extended 90% –20% voltage range provides the most accurate assessment of voltage-dependent capacitance, while the IEC 80% –40% range still remains usable whereas the narrower 90% –70% interval is more suitable for ESR evaluation at higher discharge currents. Although not designed for intermanufacturer statistics, the consistent results across all devices validate the robustness and repeatability of the proposed framework, providing a solid basis for future standardization and large-scale studies.