Why use water to extinguish the fire of lithium battery?

Lishujun, a famous lithium-ion battery expert in China, analyzed the spontaneous combustion of batteries to find the culprit that caused the fire. Mr Lishujun said there was a high probability that an internal short circuit would cause a spontaneous explosion. Lishujun also pointed out that at present, the country does not have technical supervision standards for the production process of lithium ion batteries, resulting in chaos in the industry.

There's a good chance of a short circuit inside the battery.

Lishujun is a Ph.D. in physics graduated from the Institute of High Energy Physics, Chinese Academy of Sciences, and one of the earliest people to develop lithium ion battery technology in China. Lishujun took apart a lithium battery and saw a layer of aluminum foil and copper foil, with a plastic diaphragm in the middle. Lishujun explained that during the process of lithium ion battery processing, the poles of the positive and negative poles were superimposed together, the diaphragm was strictly separated, and the diaphragm was tightly wound together. It was placed in a pre-processed shell and injected into a liquid electrolyte. And seal the opening. A lithium battery is ready. At this time, the battery itself is not electric. Only the diaphragm and electrolytes in the material are flammable, but they are not flammable and are very safe. There are no high-risk processes throughout the process, and there are no special factors for fire explosions.

However, the battery will be charged for the first time, shelved and tested before the factory. If there is a short circuit after charging, it will cause spontaneous combustion. "Short circuits are divided into internal short circuits and external short circuits. External short circuits may be caused by storage, transportation, etc., and internal short circuits are problems of the product itself." Lishujun further explained that these problems include: In the production process, The environment is unclean, causing other substances to be contaminated on the positive and negative tablets; The internal diaphragm can not effectively separate the positive and negative poles and there are defects. This will lead to the rapid release of electricity stored in the battery through the connection point, the instantaneous release of large amounts of heat, and the sharp increase in battery temperature, which will first lead to the combustion of flammable substances such as electrolytes and diaphragm, and when the temperature rises to a certain extent, Positive and negative materials and aluminum foil also burn violently, and the center temperature rises above 1,000 degrees Celsius, and similar explosions occur. If a large number of batteries are stored in a factory, it will cause a chain fire explosion.

Lithium batteries on fire. Dry powder won't put out the fire.

Lishujun said that due to the internal combustion of the battery, the use of dry powder extinguishers will not work at this time, and the best way is to use water to cool down.

Lack of standards for lithium battery manufacturing

In recent years, more and more battery spontaneous combustion and even explosion accidents, Lishujun said, the ultimate reason is that there is a blank production standards in China, leading to chaos in the industry. "External short circuits or improper consumer use rarely occur, and it is easier to avoid improper stacking and transportation within factories. For battery companies, the biggest danger is creating internal short-circuit manufacturing flaws, "Lishujun said." To avoid such defects, battery manufacturers need to have good precision processing equipment and produce in low humidity and low dust conditions. And complete monitoring and testing are carried out on each process.

At the same time, in order to avoid a fire caused by the spontaneous combustion of the recharged battery, the unmanufactured charged battery must be stored independently in a fireproof compartment, and monitoring facilities and automatic fire extinguishing devices such as smoke and spray must be installed. Operators must leave. A certain safe distance, There should be an open escape route nearby. "However, due to the existence of low-end unregulated markets such as cottage machines and charging treasures, many battery factories with very small investments use simple equipment to process and manufacture lithium-ion batteries. They lack the most basic quality control measures. There are many defects and defects in the interior of the product. The potential for fire explosions is great. At the same time, the recharged batteries are piled up at will and the people and goods are adjacent. There are no fire safety measures, and fire accidents and casualties are likely to occur. "

The reason is that there is no technical supervision standard for the production process of lithium-ion batteries.

The page contains the contents of the machine translation.