The difference between super capacitor and lithium battery

Supercapacitor and lithium-ion battery are two important energy storage batteries with high power and high specific energy. As a kind of power supply with special performance between traditional capacitor and battery, supercapacitor has the advantages of fast charging and discharging speed and long cycle use. There are many views that with the progress of technology, super capacitors will be able to replace batteries. Let's take a specific look.

The difference between super capacitor and lithium battery

According to their principle, the positive charge is gradually accumulated in the positive material and the negative charge is gradually accumulated in the negative material. Under the action of electrostatic attraction of accumulated charge, negative ions in electrolyte will be adsorbed on the surface of cathode material, while positive ions in electrolyte will be adsorbed on the surface of anode material. During the charging process, the positive potential of Li ion battery increases gradually, while the negative potential decreases gradually. Under the effect of the potential difference between the positive and negative electrodes, the oxidation reaction occurs in the positive material and the reduction reaction occurs in the negative material. The mechanism of energy storage is different. The electrode of supercapacitor adopts electric double layer energy storage mechanism, and the electrode of lithium-ion battery adopts chemical energy storage mechanism.

What are the similarities and differences between the above mentioned energy storage mechanisms.

1. From their common point of view, they all release their stored energy in the form of electric work.

2. From the perspective of application, supercapacitor is a kind of energy storage battery, which is not different from ordinary battery in structure. It is composed of positive / negative electrode and electrolyte.

3. From the essence of the principle, supercapacitors can store and release energy in the form of electric double layer mechanism, and can also store energy in the form of electrostatic energy, which directly does work by electrostatic energy when discharging. For lithium-ion batteries, the chemical energy storage mechanism and energy release, that is, the chemical way to store energy, when discharging, the chemical energy is directly converted to electrical work.

4. From the aspect of energy conversion, the energy conversion of supercapacitor is not as complicated as that of ordinary battery, there are only two forms of electric energy conversion, and there is no link between electric energy and chemical energy conversion.

5. In terms of the internal resistance, supercapacitors only have solution resistance, while ordinary batteries have electrochemical reaction impedance besides solution resistance, which is much higher than solution resistance.