What are the factors that affect the life of supercapacitors?

ESD TVS electrostatic protection tube 0201 package 3.3V ultra low capacitance ESD

Photocoupler

Supercapacitor's high energy density, long life (10 years at normal temperature, higher than battery), extremely long charge and discharge cycle life (50 to 1 million times, much higher than battery), high energy density and other excellent performance The more applications. However, in actual applications, there may be significantly lower data than the datasheet. Especially after the supercapacitors are connected in series to form a capacitor module, the parameters of the supercapacitor will appear divergence after application. Thereby, the attenuation of the single-capacitance capacity behind the capacitance is accelerated, and finally the life of the supercapacitor module is shortened. Therefore, in practical applications, it is necessary to clearly understand various factors affecting the supercapacitor, and take measures to avoid factors that are not conducive to the life of the supercapacitor.
The main factors affecting supercapacitors are: high temperature environment; applied voltage, and the elegant characteristics of the voltage equalizing circuit.
1. The impact of high temperature environment on the life of supercapacitors First look at the normal temperature life, supercapacitor manufacturers in the supercapacitor datasheet are marked at room temperature for 10 years. If the "10 degree rule" is based on the temperature and life of the electrolytic capacitor, the life expectancy at the maximum operating temperature (65 Ω) is 5475 hours, or 7.6 months and 228 days.
However, in practical applications, the high-temperature life of supercapacitors is much shorter than the calculated results. Therefore, it is necessary to analyze the reason. By carefully analyzing the datasheet, the supercapacitor manufacturers who swim in it will give high temperature lifetimes, and the high-temperature lifetimes given by different supercapacitor manufacturers in their datasheets are different. For example, a supercapacitor manufacturer gives a supercapacitor with a high temperature life of 1500 hours, while some supercapacitor manufacturers give a 1000 hour high temperature lifetime.
The reason for the difference in high-temperature life is that the manufacturing level is related to the package form. Figure 1 shows the package form of different supercapacitor manufacturers.
In the figure, the left and left 2 are the package forms of common electrolytic capacitors, and the cost is relatively low, but the high-temperature lifetime of this package is about 1000 hours (1000 hours is given in the datasheet of the left 1 supercapacitor manufacturer in Figure 1). The high temperature lifetime given by the left 3 package of Figure 1 is 1500 hours.
If the temperature is 10 years at normal temperature, the normal temperature/high temperature life ratio of the common electrolytic capacitor package is 87.6 times, and the temperature difference ΔT of the corresponding life halving is:

Equation (1) shows that the temperature difference of the life of a supercapacitor using a conventional electrolytic capacitor package is halved by about 6.2 °C. Thus, the corresponding temperature difference corresponding to the ambient temperature of 50 ° C is 15 ° C, which is 2.43 times of 6.18 ° C, that is, 1.43 times of the extra 2, the corresponding actual life is about:

That is 2694 hours. Instead of about 11,000 hours obtained by the law of 10 °C.
The ratio of the normal temperature/high temperature life of the package form on the left of Fig. 1 is 58.4 times, and the temperature difference ΔT of the corresponding life halving is:

Equation (3) shows that the temperature difference of the life of the supercapacitor using the left 3 package of Figure 1 is halved by approximately 5.87 °C. Thus, corresponding to the ambient temperature of 50 ° C, the corresponding temperature difference is 15 ° C, which is 2.56 times of 5.87 ° C, that is, 1.56 times more than 2, the corresponding actual life is about:

That is 4433.8 hours. Obviously, the result of equation (4) is 1.64 times that of equation (2). Thus, at an ambient temperature of 50 ° C, the price of a common electrolytic capacitor package is 61% of the price of the left 3 package form of Figure 1 to reach an economic equilibrium point. The high temperature life of supercapacitors needs to be considered when choosing a supercapacitor brand and specification.