Why do lithium battery factories explode into flames frequently?

There have been several cases of explosion in lithium battery factories this year. Recently there was an explosion happened in lithium battery factory of Shenzhen again—After a preliminary investigation, the explosion material was lithium battery semi-finished product in aging workshop, and its parent company has been suspended also because of "the stacked broken batteries cause fire explosion". Someone said that the reason may be Shenzhen is too hot to stand, so battery was explored. In addition, according to the survey, there was a fire happened in the factory’s warehouse on March 22. It was not put out until the next day in the morning, which caused an economic loss of 20 million yuan. These 2 fire accidents are only less than 4 months apart.

In fact, the thermal activity of lithium-ion batteries is very big, but still pretty much causes explosions, such as:

1. The temperature. Has more factors affecting the safety of lithium-ion battery, the battery materials have important effects on the safety of the lithium battery, because the battery materials with thermal activity commonly, when the battery temperature rising, the interior will be a lot of fluid, when the heat is not lost in time, it is easy to cause the battery safety accidents, so lithium battery anode materials are selected and has important effect on the battery safety performance.

2. The manufacturing process. Battery manufacturing process is also the important factors that affect the battery safety performance, one of the main three factors, respectively is negative ratio of capacity, size uniformity, coating quality control.

In use process, large current (external short circuit, short circuit) caused by an explosion caused by overheating. Burst might make charge not stable anode (sedimentary lithium) contact with air, resulting in a large number of heat release and/or negative capacity is insufficient; Charge/discharge can also cause explosion.

How powerful is a lithium battery explosion?

Half zhihu netizens flying fish: explosive power I don't know how to quantitative characterization, I think with hard shells Lithium ion batteries are very damaging to the explosion. Was 2.5 Ah 18650 explosion, and the steel shell can be turned completely, not open the lid, is blowing the steel shell to a piece.

Zhihu netizen admire old pei: the perceptual description under the explosive power of a lithium ion battery. Shell for aluminum alloy, size is 20120300 (mm), manganese acid lithium batteries are extremely capacity of 50 ah did impact testing battery explosion: 3 meters high roofs blackened, half a meter away from the battery blast through a hole in the wall (wall brick or sandwich board forget), door window glass broken. No one is good Fried.

Zhihu netizen Zheng Na: carry UL standard with lithium batteries: requirement when thrown into the fire battery explosion blast radius is not greater than 1 m. Of course, the greater the mah capacity, explosive power. Like a fireworks and firecrackers exploding. “Exception: cylindrical battery capacity is less than 300 mah or button battery, if the test shows that these risks are no request id."

How much difference is a lithium battery explosion in between full charge and empty one?

Debate about this problem, there are two factions, a man-made explosion has nothing to do with full working hours/empty electricity (irrelevant), a kind of believe that there is a relationship (relevant).

A representative of irrelevant: Wugai from Zhihu.com

"How does it explode? Everyone knows that the battery is a closed system of tin (aluminum-plastic film becomes the balloon explosion), and the fluid inside the battery are organic electrolyte, when high fever or overcharge, very easy to decompose organic matter gasification, results in a pressure surge in the battery, resulting in explosion.

From here you can see, the explosion is mainly caused by the electrolyte decomposition and gasification, with full power, air power has nothing to do. If from the point of view of the cause, full battery easy to explode, and it is not easy to empty electrical explosion. See it that way, the possibility of full electric battery explosion and power will be great."

A representative of relevant: Mark from Zhihu.com

"It is a big difference between full charge battery and an empty battery explosion. The explosion principle of these two conditions is not exactly the same.

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