Electric double-layer capacitors (EDLCs) are widely used as electrochemical energy storage devices for various electric devices because of their excellent electrochemical properties, such as fast charging, greater power density than that of lithium-ion batteries, and superior cyclability. Cell optimization is necessary for enhancing the electrochemical performances of EDLCs. In this study, cell optimization was performed using cathode/anode balancing and several electrolyte additives. Cathode and anode balancing is conducted by controlling the cathode thickness from 140 to 220 μm. Consequently, EDLCs assembled with a cathode (200 μm) and anode (120 μm) show good cyclability at 3.2 V. Furthermore, the EDLC prepared with 1.0 M SBPBF4/ACN + PS showed favorable cycle stability for 500 cycles.