Online proceedings - EDA Publishing Association

24-26 September 2008, Rome, Italy0.14 S -1 .m -1 by fitting the cell voltage between 0 and 2 Volt(see Figure 7). Finally, calculations were found in quite good2,8agreement with thermal measurements, as shown in figure 6.2,6Dissipated power (W)0,40,2as measuredas calculatedCapacitance (F)2,42,22,01,81,60,0 0,5 1,0 1,5 2,0 2,5 3,0initial potential of the cell (V)0,0100 200 300 400 500 600 700Charge current (mA)Figure 6: Dissipated power measured and calculated, as a function of thecharge current.Voltage (V)1,51,00,5BChargeslopeexperimentalmodelA0,00 1 2 3 4 5 6Time (s)Figure 8: Capacitance as a function of init potential, as measured on a C-Ccapacitor cellCurrent distribution in the cell is non-uniform as shown inFigure 10. Energy is found stored near the electrodeseparatorinterfaces, and at any point of the cell the chargesstorage rate is constant after a certain time. Time domainwhere the charge slope is constant defines a sliding regime.Heat is none uniformly generated into the cell and dissipatedpower exhibit a temporal profile as represented in Figure 11.However, one demonstrates that dissipated power referring tothe sliding regime is constant and can be expressed by thefollowing relation:( − 1 −+1 ) . I22. lP = κ3. Sσ (4)This can be estimated by measuring the voltage differenceVA – VB represented in figure 7, where VB defines thecharge resistance, and VA the input resistance beforecharging.Figure 7: Cell voltage as a function of time, as measured on a carbon cellafter applying 0.4 A as charge current. Potential window was 0-2 Volt.Figure 9: Schema of a Double-Layer Capacitor©EDA Publishing/THERMINIC 2008 227ISBN: 978-2-35500-008-9