Eight Thoughts on Spontaneous Combustion of New Energy Vehicles

Huang Xuejie: Eight Thoughts on Spontaneous Combustion of New Energy Vehicles

Abstract: Huang Xuejie, vice chairman of the China Battery Industry Association, researcher and doctoral supervisor of the Institute of Physics of the Chinese Academy of Sciences, explained in detail the safety and future of electric vehicle batteries.

Since the beginning of this year, Weilai, Tesla and other well-known brands have been frequently involved in electric vehicle safety accidents. Recently, Huang Xuejie, vice chairman of the China Battery Industry Association, researcher and doctoral supervisor of the Institute of Physics of the Chinese Academy of Sciences, explained in detail the safety and future of electric vehicle batteries.

1.What conditions will cause electric vehicles to ignite spontaneously?

Huang Xuejie: Although the line is aging, damaged and placed in the car, it will easily cause short circuit and trigger spontaneous combustion. However, the main reason for self-ignition of electric vehicles is caused by the heat loss of the battery and the heat spread.

There are positive and negative electrodes, electrolyte and diaphragm in the battery, and there are many combustible materials. Causes of self-ignition of the battery include external short circuits or internal short circuits. There is a trauma, such as a battery pack damaged by a collision or a short circuit outside the battery pack. The internal short circuit caused by the battery manufacturing defect, the car seems to have no problem temporarily, but there has been a micro short circuit inside, and it may burn after a while. When the battery is overcharged, the temperature rises rapidly and the thermal runaway spontaneous combustion occurs.

There is also a situation in which the battery management system has a problem that causes the battery to overheat, and the diaphragm melts to cause a short circuit inside the battery, which in turn causes the battery to be out of control.

2.The recent spontaneous combustion events have some things in common. First of all, they are not new cars. They belong to the old models and have been used for a certain mileage. Can it be understood that the longer the power battery is used, the more dangerous it is?

Huang Xuejie: The electric vehicle industry needs better batteries. Everyone is still working hard. But before that, we can only choose a battery that can at least let the car run. This is a compromise. Sometimes the battery is reduced in safety over time, and there are cases of low intensity overheating, overcharging problems, or mechanical damage and circuit failure during use.

3.At present, electric vehicle charging, there are three modes of fast charging, slow charging and battery replacement. What is the mainstream and safe charging mode?

Huang Xuejie: The electric vehicle fast charging and slow charging interface correspond to DC and AC interfaces. Under normal circumstances, you should use slow charging as much as possible, and use the fast charging method only when you need it urgently. Because fast charging is very demanding on the battery, high current charging will cause the battery pack temperature to rise and the battery to decay faster.

4.What kinds of lithium batteries are currently used in electric vehicles at home and abroad? What are the problems in the recycling process?

Huang Xuejie: Carbon emissions are inevitable in the battery manufacturing process, and the energy supply is not perfect, but the current pollution level of electric vehicles is lower than that of internal combustion engines. In terms of battery production, people already have some experience, from source to production can control pollution and improve environmental protection.

However, the battery has a long service life. When it is scrapped, many chemicals in the battery need to be processed, and the disposal of the discarded battery is just beginning. This problem definitely needs to be solved, which is one of the producers' responsibilities. It is necessary to improve the cycle life of the battery to achieve cascade utilization, develop more efficient dismantling and recycling technologies, reduce the mining demand for new materials through recycling, and improve environmental benefits.

5.How is the electric vehicle battery manufacturing technology in China?

Huang Xuejie: Foreign mainstream power battery companies and some domestic technology leading companies benefit from automated production technology, process equipment and quality control level, especially automation control technology, intelligent unmanned manufacturing plants, etc. can guarantee the production of high quality and high level of power. Battery products.

6.Is there a safety hazard such as radiation in the power battery?

Huang Xuejie: No, there is no radiation problem in the battery.

7.Are new materials such as graphene and black phosphorus used to make electrodes, which will revolutionize battery technology?

Huang Xuejie: There are many people studying the new electrode materials. Graphene is useful as a conductive additive material in the positive electrode. Generally, the addition amount is less than one percent. Black phosphorus is also used as a negative electrode material, but no application is possible. Sex.

The hydrogen fuel cell directly converts the chemical energy of the fuel into electric energy, which can meet the application requirements of specific models and specific scenarios, and will effectively complement the electric vehicle power.

8.What warnings does the self-ignition accident bring to the electric vehicle industry?

Huang Xuejie: Compared with traditional fuel vehicles, the maturity of electric vehicles is not enough. The marketization process still faces some bottlenecks. Power battery is one of the key components of electric vehicles. We should rely on advanced technology to solve the problem of high battery cost, insufficient safety and reliability, and inconvenient use.