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Why do lithium batteries explode? How likely is the lithium battery to explode

January 18, 2021

Why do lithium batteries explode? How likely is the lithium battery to explode

 

Lithium batteries are used in many electronic devices, and we are usually familiar with lithium batteries. In the previous article, the editor introduced a lithium battery protection board and the lithium battery protection board's purchase points. To improve everyone's understanding of lithium batteries, this article will analyze the causes of lithium batteries' explosions and fires and discuss the explosion probability of lithium batteries. If you are interested in lithium batteries, you may wish to continue reading.

 

1. Why did the lithium battery explode and catch fire?

 

 

18650 li battery

1. The negative capacity of the lithium battery is insufficient

 

When the capacity of the negative electrode part of the positive electrode part of the lithium battery is insufficient, the lithium atoms generated during charging cannot be inserted into the interlayer structure of the negative electrode graphite. They will precipitate on the surface of the negative electrode to form crystals. The long-term formation of crystals in lithium batteries can cause short circuits. At this time, the battery cells are rapidly discharged, which will generate a lot of heat and burn the diaphragm. The high temperature will decompose the electrolyte into gas, and when the pressure is too high, the cell will explode.

 

2. The moisture content is too high

 

When charging, water can react with lithium to generate lithium oxide, which will cause the capacity of the battery cell to be lost, and it is easy to overcharge the battery to create the gas. The decomposition voltage of water is low, and it is easy to decompose to generate gas during charging. A series of generated gas will increase the cell's internal pressure, and when the shell of the cell cannot withstand it, the cell will explode.

 

3. Internal short circuit

 

The short-circuit of the internal battery cell causes a large current discharge, generates a lot of heat, burns the diaphragm, and causes a more significant short-circuit phenomenon, which will decompose the electrolyte into gas. If the internal pressure is too high, the battery cell will explode.

 

4. Lithium battery overcharge

 

When the battery is overcharged, lithium's excessive release in the positive electrode will change the favorable electrode structure. If too much lithium is released, it is easy to be unable to be inserted into the negative electrode, and it is also easy to cause lithium deposition on the surface of the negative electrode. Moreover, when the voltage reaches 4.5V or more, The electrolyte will decompose to produce a large amount of gas. All of the above may cause an explosion.

 

5. External short circuit

 

The external short circuit may be caused by the wrong connection of the positive and negative electrodes. Due to the short outercourse, the battery discharge current is enormous, which will cause the battery core to heat up.

 

Second, the probability of a lithium battery explosion is large or small.

 

Are lithium batteries easy to explode? How powerful is the explosion of lithium batteries? Although lithium batteries are generally very safe, they can occasionally catch fire or explode. We often see various safety accidents caused by lithium batteries. The most impressive thing is the explosion and fire caused by lithium batteries.

 

Lithium batteries have been developed for more than tens of years since their birth. Most mobile phones currently on the market also have built-in lithium batteries. Despite decades of development, lithium batteries still cannot guarantee 100% safety. In the environment, an explosion may even occur.

 

Lithium is excellent in terms of reserves. When it is released as a trickle, it will power your phone for a whole day. But when it is released all at once, the battery will explode. Short circuits cause most lithium battery fires and explosions. This happens when the plastic separator fails, allowing direct contact between the anode and cathode. Once the two poles come together, the battery will start to overheat.

 

As long as it is a lithium battery, there is a risk of explosion, but this is a small risk. But once it explodes, the power of a lithium battery with a larger capacity will be unimaginable.

 

There are two fundamental causes of lithium battery explosion, one is a short circuit, and the other is an overcharge. The short course is easy to understand; that is, the battery's positive and negative electrodes are in direct contact. First, in a standard short time, the heat generated by a short circuit in a small area is minimal, and it will not cause thermal runaway. An explosion-proof valve is used in the design of the cell itself, which means that when the internal pressure of the cell exceeds a specific value, the explosion-proof valve will be opened, and the heat will quickly dissipate. The second is that the battery charging equipment in everyday use is protected against overcharge, and when the battery voltage reaches an absolute value, it will stop charging. The shell of the third cell itself is a steel shell, which has adequate protection.