The last insurance for electric cars: What is the correctness of the power lithium-ion battery?

　　Author ：Iflowpower – Portable Power Station Supplier

Recently, multiple electric vehicles have pushed the safety of dynamic lithium-ion batteries again, and the three-yuan material replaced lithium iron phosphate material battery also leads to battery safety while bringing new motor vehicle life. Decrease, it is easy to cause safety accidents such as power lithium ion battery when crash accidents. In order to add the escape time of the passengers in the car when the power lithium-ion battery has a combustion accident, it is generally necessary to add a fire extinguishing system inside the battery box to suppress the spread of thermal out of control in the battery box.

Unlike traditional organic, there is a reducing agent in the battery system, and also contains an oxidant. Therefore, the simple isolation of air does not prevent the combustion of the lithium ion battery, that is, the traditional fire extinguishing agent is not necessarily suitable for the power lithium-ion battery fire. Dynamic lithium-ion batteries have the following features: 1.

Fast, the long-term growth is based on NFPA (US Fire Association) test, the fire is only a few seconds in the dynamic lithium-ion battery module, continues about 27min. 2. A large feature of the combustion temperature high-powered lithium ion battery is high, according to NFPA tests, the outer temperature of the battery can reach 283-1090 degrees Celsius, the temperature of the battery can reach 572-1121 degrees Celsius, so high The temperature is sufficient to ignore other combustible materials inside the battery module and other combustible materials in the car, there is a larger fire.

3. Difficult to extinguish the dynamic lithium-ion battery, most combustion reactions occur in the inside of the battery case, the outer casing hinders the use of fire extinguishing agents, and the extinguishing time of the dynamic lithium-ion battery fire often exceeds the firefighter The oxygen cylinders have a certain threat to the personal safety of firefighters. In order to verify the extinguishing effect of different fire extinguishing agents, the US Federal Administration FAA detected aqueous fire extinguishing system such as water, AF-31, AF-21, etc.

, gas fire extinguishing agent, such as FM-200, Fe- 36, as well as dry powder fire extinguishing agent, the cooling effect of the fire extinguishing agent is a key factor affecting the fire extinguishing effect, so the water-based extinguishing agent is the best, and the dry powder and gas fire extinguishing agent are basically not available to the lithium-ion battery. Effect. Some research institutes in my country, such as research on my country's Science and Technology, etc.

, extinguishing agents such as carbon dioxide, dry powder on fire extinguishing of lithium-ion batteries, in fact, this is not difficult to understand, this is because these fire extinguishing agents By isolating oxygen in the air, the combustion reaction cannot be carried out, but in the lithium ion battery, the positive electrode material, in particular, the positive material material in the charging state is a strong oxidant, and the negative electrode active material, the electrolyte, etc. The reducing agent has a basic combustion condition, so the general isolated air-type fire extinguishing agent does not play the lithium ion battery fire, but there is a fire extinguishing agent that can quickly cool the effect, quickly take away the heat of the combustion, so that combustion The reaction does not have the conditions to continue, in order to extinguish the lithium-ion battery fire. Although water is very good as a fire extinguishing agent is very good, there is still a lot of problems in actual use, such as long extinguishing time, large water consumption, so water is not a very efficient fire extinguishing agent.

In 2009, Germany Bochi explored the effect of water, foam, dry powder and F-500 (a micropipinated agent, developed by AmericanGroger jobs). Bosch's probe declaration F-500 fire extinguishing agent is a power lithium-ion battery fire The best choice, the 2013 German Motor Vehicle Inspection Association (DEKRA) also declares that F-500 is an efficient dynamic lithium-ion battery fire extinguishing agent, which can significantly shorten the extinguishing time of power lithium-ion battery fires and reduce fire extinguishing. Excluding consumption.

The working principle of the F-500 fire extinguishing agent is to effectively reduce the surface tension of water by additive, thereby forming a small water droplet while spreading, and the water droplets can spread to the inside of the lithium ion battery, rapidly absorb heat, and achieve the effect of fire extinguishing. At 2017, the International Seminar of Fire Science and Firefighting Engineering, Weitaoluo (First Servers) and SHunbingzhu (Corresponding author) of Nanjing University of Technology decomposed different fire extinguishing agents on fire-fighting lithium-ion battery fires. In the test, the authors used 18650 batteries as a research object, which detected pure water, 5% F-500 solution and its own configured 5% solution (anion / nonionic surfactant) to the lithium ion battery fire, and also detected Water fog's extinguishing effect on lithium-ion battery fire.

From the test results (as shown below), the effect of the F-500 fire extinguishing agent and the anion prepared by the author, the effect of the nonionic solution fire extinguishing agent is better than the pure water extinguishing agent, and the temperature of the two fire extinguishers is rapid. Decline, lithium-ion battery fire is rapidly extinguished, compared to pure water, fire extinguishing time is shortened. The author's test statement even uses spray fire extinguishing, F-500 fire extinguishing agent and the anion of the autonate, the effect of nonionic solution fire extinguishing agent is also clear than pure water, only 4 seconds, can effectively inhibit lithium ions.

Burning of the battery. It is not difficult to see from the above decomposition, although pure water can extinguish the lithium-ion battery fire, but the efficiency is very low, the extinguishing time is long, the water consumption is large, so it is not suitable for electric vehicles limited space, escape time is very precious. However, the F-500 fire extinguishing agent causes water to form tiny droplets by lowering the surface tension of water, thereby greatly improving fire extinguishing efficiency, making the fire extinguishing time significantly, and the amount of fire extinguishing agent has been greatly reduced, and it is very suitable for use on electric vehicles.

Even in some special occasions such as aircraft, it is possible to use this type of fire extinguishing agent to rapidly extinguish the fire when the electronic equipment battery is burned.