Supercapacitor Assembly & Electrochemical Characterization

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In this lab at ETH Zürich's Electrochemical Energy Systems Laboratory, we hand-assembled symmetric supercapacitors from scratch using activated carbon electrodes, a glass fiber separator, and a sulfuric acid electrolyte in a Swagelok cell configuration. Once assembled, we connected the cell to a BioLogic potentiostat and ran cyclic voltammetry at scan rates ranging from 1 to 100 mV/s to measure gravimetric capacitance and observe how charge storage behavior changes with speed. We also tested the effect of increasing the voltage window beyond the electrolyte's stability limit, watching parasitic reactions appear in real time in the CV curves. Finally, we performed galvanostatic cycling to calculate coulombic efficiency and assess cycle life. We processed and plotted the data in MATLAB, and our report connected experimental results to theoretical models such as the Helmholtz double layer framework.