The working characteristics of double layer capacitors

The working characteristics of double layer capacitors

Compared with aluminum electrolytic capacitors, double-layer capacitors have higher internal resistance, so they can be charged directly without load resistance. If overvoltage charging occurs, double-layer capacitors will

This characteristic is different from the overvoltage breakdown of aluminum electrolytic capacitors, as it does not damage the components. Meanwhile, compared to rechargeable batteries, double-layer capacitors can perform unlimited current charging and charge multiple times

More than 10 ^ 6 times, therefore, the double layer capacitor not only has the characteristics of a capacitor, but also has the characteristics of a battery. It is a new type of special component that lies between the battery and the capacitor. 

When charging the electrode, the surface charge of the electrode in the ideal polarized electrode state will attract foreign ions in the surrounding electrolyte solution, causing these ions to attach to the electrode surface to form a double charge layer, forming a double layer capacitance. Due to the very small distance between the two charge layers (usually below 0.5nm), coupled with the use of a special electrode structure, the electrode surface area increases by tens of thousands of times, resulting in a huge capacitance. The schematic diagram of a double layer capacitor is as follows:

The characteristics of double layer capacitors:

(1) High power density

It can reach 102-104 W/kg, far higher than the power density level of batteries.

(2) Long cycle life

After 500000 to 1 million high-speed deep charge discharge cycles in a few seconds, the characteristics of the double-layer capacitor change very little, and the capacity and internal resistance only decrease by 10% to 20%.

(3) Working temperature limit

Due to the small changes in the adsorption and desorption rates of ions in double-layer capacitors at low temperatures, their capacity change is much smaller than that of batteries. The operating temperature range of commercial double-layer capacitors can reach -40 ℃ to+80 ℃.