CELL BALANCING IN A MULTICELL CAPACITOR THROUGH VOLTAGE REGULATION USING DIODES IN PARALLEL TO EACH CELL
Original Publication Date: 1998-Sep-01
Included in the Prior Art Database: 2002-Jul-17
Multi-celled, electrochemical capacitors have a tendency to become unstable if operated on or near their maximum rated voltage (i.e. 1.2V per cell for aqueous electrolytes) for a long time. The long time instability arises due to variations in the leakage resis- tance between cells in the bipolar stack. These capaci- tors are composed of individual cells of approximately 1-4 mils thick stacked on top of each other. To over- come the voltage instability, we show that connecting diodes in parallel to each cell alleviates this problem. This method could be achieved by either connecting diodes externally to each cell in a multicell device or by integrating the diode elements at the rim of the sub- strate during the manufacturing process. The diodes required in this application are of very small size and could also be embedded in the sealant epoxy used at the border of the electrodes.