With the increasing number of pure electric vehicles in China, the news about the fire accidents of pure electric vehicles has also begun to "brush the screen" frequently, making the safety of electric vehicles the focus of the whole society, and also touching the anxiety of consumers about safety. For a time, the electric car is not reliable, battery technology is not mature and other issues, once again triggered a wide range of discussions. So, the question is, who is the culprit of electric vehicle fire? How to solve the safety hazard of electric vehicle fire?

According to industry experts, the battery is the main culprit of electric vehicle fire, including battery short circuit, improper operation, and collision and extrusion, which will lead to battery fire. Therefore, to solve the safety hazard of electric vehicle fire, it is undoubtedly to start from the power battery technology breakthrough.

At present, most of the batteries of electric vehicles in my country use ternary lithium batteries and lithium iron phosphate batteries. In order to pursue lightweight and improve energy efficiency ratio, ternary lithium batteries obviously have more advantages.

Compared with lithium iron phosphate batteries, ternary lithium batteries are smaller in size and higher in density, which is more in line with the lightweight requirements of electric vehicles. However, it is precisely because of its active chemical characteristics that it is very easy to react with the oxygen in the air, resulting in combustion and explosion.

"The energy density of the ternary lithium battery is relatively high (140Wh/kg), which has a greater impact on the battery core in the' fast charging 'and' fast discharging' modes. However, the lithium iron phosphate battery has a lower energy density (110Wh/kg) and has less impact on the battery core in the' fast charging 'and' fast discharging' modes. On the whole, the lithium iron phosphate battery has higher safety.

As an energy storage and functional device used in new energy vehicles, lithium batteries have the reputation of being the heart of pure electric vehicles. As the core component of electric vehicles, power batteries account for half of the cost of the entire vehicle. According to the structure of electric vehicle power batteries, The battery pack used in general vehicles is composed of many small batteries connected in series. In terms of battery structure, the internal materials of these batteries include negative electrode material, electrolyte, diaphragm and positive electrode, it mainly relies on lithium ions to move between the positive and negative electrodes to work. According to the characteristics, when the electrode material inside the battery appears, overcharge, overheating, and puncture will explode. Although the safety is much better, there is still a risk of burning.

From the point of view of many electric vehicle fire accidents, they basically have a certain relationship with the battery. The number of lithium batteries on electric vehicles can range from hundreds to thousands. Especially for the battery management technology of vehicles, it is not easy to manage the technology. For the risk of spontaneous combustion of vehicles, even the high-end new energy vehicles Tesla is not immune in this area. The risk of combustion has a certain relationship with the working environment of the battery and the design of the battery. From the perspective of the design and production of the battery, it is impossible for the manufacturing equipment and testing equipment to be 100% fully qualified batteries, especially for the battery Internal cathode materials, anode materials and electrolyte.

There are slight technological deficiencies and design weaknesses, which will become a hidden danger of micro-short-circuit spontaneous combustion in lithium-ion batteries. In addition, although the current standards for battery testing and production are mainly national standards, there are still different methods and methods for quality control. In terms of use, when the vehicle scratches the chassis, the lithium battery will be short-circuited. Secondly, when the vehicle is quickly charged, the amount of electricity is too large, resulting in the internal electrolyte being vaporized and decomposed by heat. Finally, the battery shell is ruptured due to too much pressure, and high-pressure gas is ejected from the rupture, the gas quickly diffuses to the weak point of the battery pack, thus causing the risk of spontaneous combustion.

One of the zui bottlenecks in the development of new energy vehicles is the power battery. The risk of spontaneous combustion is one of the major reasons for the zui of new energy vehicles and also comes from the power battery. Of course, how to make lithium-ion batteries no longer burn is also what many car companies and battery manufacturers are committed to researching and solving.

At present, the lithium battery industry has gradually formed an increase in the safety awareness of a firewall, the use of gas sensors to monitor the lithium battery fire, lithium batteries before the fire will usually produce a large number of methane, propane, CO, hydrogen and other gases, so monitoring CO, methane, propane The concentration is undoubtedly an effective solution. With this solution, the sensitivity and reliability of the gas sensor are usually relatively high. Here, the technology recommendCarbon Monoxide Sensor TGS5141andCombustible gas sensor TGS2610For electric vehicle fire detection:

TGS5141 sensor has the advantages of high sensitivity, good reliability and long life, which is very suitable for electric vehicle fire detection.

Carbon Monoxide Sensor CO Sensor TGS5141Main parameters:
1) Carbon monoxide detection range: 0-5000ppm
2) Output current: 1.2-3.2nA/ppm
3) Response schedule: <60S
4) Working temperature:-10 ℃ ~ 50 ℃ (commonly used) -20 ℃ ~ 60 ℃ (occasionally)
5) Working humidity: 10 - 95% RH (no condensation)

TGS5141 with small size, low power consumption, long life and other advantages, very suitable for high integration, battery-powered products, not only can be used for lithium battery production, storage environment, can also be used for new energy vehicles and other product applications. The sensitivity of the TGS5141 to CO is very high, and the anti-interference ability of methane, alcohol and other combustible gases is strong, which ensures the accuracy of the battery fire detection.

Combustible gas sensor TGS2610 has a high sensitivity to propane and butane, is a good LPG monitor, because of its volatile alcohol (living environment common interference gas) sensitivity is very low, so for gas leak alarm is an ideal sensor. Due to the small size of the sensitive element, the TGS2610 heater current only needs 56mA, and the detection part of the sensor is stored in a standard TO-5 metal package. The TGS2610-C00 is not only small in size, but also has excellent responsiveness. Is a good choice for gas leak detector. The TGS2610-D00 is equipped with a filter cover that can eliminate the influence of interference gases such as alcohol, and has a sensitive characteristic of high selectivity to LP gas.

Combustible gas sensor TGS2610 main parameters:
Combustible gas detection range: 500-10,000ppm
Sensitivity (resistance ratio):0.50-0.62
Heater voltage: 5V ± 0.2V(DC/AC)
Circuit voltage: 5V ± 0.2V(DC/AC)