TOB New Energy has always been committed to the safety of lithium battery research, especially for the lithium battery cap, now we provide a lithium battery cap pressure test equipment, specializing in the research and safety production of lithium battery.

What is the PTC and CID in lithium-ion battery caps?

For more safety and stability, the Lithium-ion battery cap has a twofold protection in the internal design. One is PTC (Positive Temperature Coefficient), a thermistor; the other is CID (Current Interrupt Device), a safety explosion-proof valve.

First, PTC is a recoverable protection. PTC is a thermistor with a positive temperature coefficient. When the internal current of the cell is too large, or the external short circuit occurs, the internal temperature increases, and the PTC resistance increases, so the battery is equivalent to being in broken circuit. When the temperature decreases, the resistance value recovers and the cell returns to normal output. This protection prevents the cell from discharging at high temperature and better protects the safety of the cell.

CID belongs to the protection of non-recovery, safety explosion-proof valve, also known as self-destruct device, is the last barrier of the battery cell security protection. When the battery cell is overcurrent at high temperature, overcharge and external short circuit, the internal air pressure increases, and when it reaches a certain value, CID is driven by air pressure and separated from the positive cap, and there will be no output of 0V outside the cell. CID is not recoverable, When the battery cell is used in abnormal conditions, CID prevents the safety hazard of explosion and fire of the battery cell, and is an indispensable part of the battery cell safety.

Our TOB-CID-6.0 two-station lithium battery and cap pressure testing machine is a device developed specifically for CID testing. It has two working stations. The first is to conduct random inspection of the outage pressure and bursting pressure of the incoming materials of the cap, and the other is to check the empty shell lithium battery, samples are randomly inspected for outage pressure value, burst pressure value and sealing air tightness. The empty shell lithium battery used for sampling refers to the finished product of the normally produced non-filled lithium battery, or the sample specially used for testing without battery cells. It is necessary to drill a small hole in the center of the bottom of the negative electrode of the empty shell lithium battery, and at the same time, ensure that the negative electrode of the cap is connected to the shell to perform the test.

In particular, if it is to detect the lithium battery which is already filled electrolyte, since the positive electrode of the lithium battery faces down during the detection, the flow of the electrolyte will make the breakpoint of the cover plate unable to be disconnected, resulting in the failure to read the breaking voltage value.

As for the air tightness test, a special fixture assembly is added to the equipment to detect the air tightness of lithium battery samples by using the method of dripping water and observing air bubbles with eyes.

We, TOB New Energy, as a professional lithium ion battery machine and material supplier, who has specialized in this field more than 18 years. If you are interesting with latest lithium ion battery raw material, R&D equipment and production line solution, please contact us for more details.