The side voltage of the lithium battery specifically refers to the voltage of the aluminum layer between the positive ear of the pouch battery and the aluminum plastic film.

Theoretically, the aluminum layer between the positive electrode and the aluminum-plastic film is insulated, that is to say: their voltage should be 0

In fact, during the processing of the aluminum-plastic film, the PP layer of the inner layer will be locally damaged, resulting in local conduction (including electron channels and ion channels) between them, forming a micro-battery, resulting in a potential difference (voltage).

The edge voltage standard varies among manufacturers, but most of the industry is set below 1.0V, and the voltage standard is based on the dissolution potential of aluminum-lithium alloy!

Why control the side voltage?

Because if the inner PP film of the aluminum-plastic film is damaged, the capacity will be corroded and damaged.

There must be two conditions for corrosion: 1. The electronic path, the negative electrode and the aluminum layer of the aluminum-plastic film form an electronic path; 2. The ion path, the aluminum layer of the aluminum-plastic film and the electrolyte form an ion path; lack of any one, corrosion Neither is established.

After both conditions are established, lithium ions will react with the aluminum layer of the aluminum-plastic film to form lithium-aluminum alloy; and lithium-aluminum alloy is a powdery substance, which causes the aluminum-plastic film to pierce; that is, we often see There are some black spots inside the aluminum plastic film; these black spots will become more and more obvious with time and the number of charge and discharge.

How to choose?

The detection methods currently counted are:

1. Test the resistance between the aluminum-plastic film and the negative ear. It is relatively safe if it is greater than 5M ohms. Some companies define it relatively low. Look at the final PPm of the defective products that you endure. You can calculate some data and then define your own standard. Yes; this resistance test is mainly to select the electronic path;

2. Test the current between the positive electrode and the aluminum film, which can be tested with a DC source. It is generally considered that the current is greater than 0.001mA, which is a defective product and needs to be picked out;

3. Test the voltage between the positive electrode and the aluminum film. Generally speaking, it is considered to be a defective product if it is greater than 1V.

Can be tested with 1 and 2, or 1 and 3.