NIPPON CHEMI-CON CORPORATION

As shown in Fig. 1, the service life of supercapacitors is greatly affected by the ambient temperature at which they are used. A lower temperature during actual use can be expected to result in a longer service life.

[Fig.1] Durability test (temperature parameter)

As shown in Fig. 2, the service life of supercapacitors is greatly affected by the applied voltage at which they are used. A lower applied voltage during actual use can be expected to result in a longer service life.

[Fig.2] Durability test (voltage parameter)

Because supercapacitors have internal resistance, the internal heat generated by charging and discharging affects their lifespans. Applications which entail continuous charging or discharging at large currents are particularly likely to accelerate degradation due to the accompanying increase in temperature. This rise in temperature due to heating should be taken into consideration as heat generation varies greatly according to charge/discharge pattern. Also, consideration should be given to voltage drop as it generates heat at the beginning or end of discharge when larger currents are used.

Two factors that contribute greatly to shortening the service life of supercapacitors are temperature and continuously applied voltage. As Fig. 3 shows, there is a linear relationship between change in electrical properties and the square root of test time. This can be expressed with the following formula.

[Fig. 3] Example of √t plotted on durability test