The role of explosion valve in lithium ion battery

Recently, many fire accidents involving lithium -ion batteries have occurred. I think everyone has become more and more concerned about battery safety. Here is an overview and positioning of lithium -ion battery safety testing. Typical security tests include over -charging testing, external short -circuit testing, over -discharge testing, and internal short -circuit testing. In order to improve the safety of lithium -ion batteries, square batteries are equipped with explosion -proof valves.

1、What is the explosion -proceed valve of lithium ion batteries?

Lithium ion batteries, especially square lithium -ion batteries (large), have an explosion -proceed valve on the top of the battery box, which is easy to open to prevent the battery from exploding when the internal pressure is increased. When abnormalities, attachment is very common. When the battery is abnormal, due to short -circuit or charging inside, various reactions will occur inside the battery (such as evaporation reactions of electrolytes, oxidation and decomposition of electrolytes, reactions of negative and electrolytes, etc.), resulting in damage to the battery. Creating heat and gas, which means explosion.

If the explosion -proof valve is not set, the gas is generated, and the pressure generated inside the battery has no place to release, and the battery will cause extremely high internal pressure. If it cannot bear it, it will explode. In other words, valve operation is extremely important for maintaining battery safety. The driver of the valve is also called exhaust.

However, in the layer pressure batteries used in smartphones and electric vehicle batteries, the sealing part of the layer pressure material will tear when the internal pressure rises to play a role of explosion -proceed valve. Therefore There are many.

2、What characteristics do explosion -proof valves need to have?

The characteristics required for explosion -proceed valves include the following content:

①Valve work pressure (exhaust pressure) must be constant

If the work pressure of the valve changes greatly, it will not work even if the valve is under high pressure, and the explosion as described above may occur. Therefore, it is necessary to maintain strict quality control, such as ensuring that the rate of bad products is lower than PPM. The number of explosion -proof valve manufacturers is limited, because only companies with precision processing technology can reduce deviation.

② It must meet the Qi -density circulation test standard

When evaluating the explosion -proceed valve, we conducted a test called Qi Tann Test. This is because even if the battery does not enter an abnormal state, as the battery ages, chemical reactions gradually occur inside the battery (such as the side reaction of the growth of the negative ELI membrane growth), and the internal pressure increases slightly, resulting in the shutdown valve. Tests, evaluate the durability of the materials in the state of continuous slight stress.

Simply put, Qi Cycling Test is a test of evaluating the fatigue characteristics of explosion -proceed valves. In addition, because households are mostly square batteries, their warranty period is often about 10 years, so explosion -proof valves must also be designed for 10 years. Each company will evaluate the standard to determine whether it can last for 10 years.

③Easy to welded or forming

Even if the explosion -proof valve itself can be made and quality is good, in order to use it as a battery component, it must be welded to the top or integrated mold of the shell to the top of the shell. Regarding the welding, if the material is the same as the top of the case (because the case is generally stainless steel or aluminum), but if it is integrated, the processing manufacturer is technically selected carefully.

Like any component, the cost is very low.