From November 20 to 21, the "2019 China Safety Industry Conference and the third traffic safety industry summit" hosted by cheyun.com and co organized by electric state was held in Foshan, Guangdong Province. With the theme of "safe travel and smart future", the summit consists of three sub venues: new energy vehicle safety, new technology safety and smart traffic safety. Representatives of the enterprises who come to Foshan for self production, study, research, etc. and travel safety gathered to discuss the new safety problems in the automobile industry under the background of the new four modernizations. During the summit, Chen Quanshi, a professor of the school of vehicle and transportation of Tsinghua University and honorary director of the electric vehicle branch of the Chinese society of automotive engineering, delivered a speech on the theme of "safety of new energy vehicles and power battery packs".
The following is the actual record of the speech:
Good afternoon, leaders and experts! It's a great honor to have this opportunity to discuss with you the safety issues of electric vehicles and new energy vehicles. At present, this is really a matter of concern to all of you. For me, I have built a car all my life. There are four aspects of the car's performance. The first is safety, the second is fast, the third is comfort, the fourth is economy and safety. If the vehicle is not safe, I guess No one is going to sit, so safety is a key issue.
Just now, the host said that from last summer to this summer, there were frequent electric vehicle fires. I started to make electric vehicles from 1985 to 1991. When the project was to be accepted in 1995, our leaders prepared to write acceptance materials. On March 10, 1996, a fire broke out in the afternoon, and the experimental data were also in it. It was during the two sessions, when the lead acid battery was still in use. The leaders of Beijing Municipal Safety Supervision Bureau and the Safety Supervision Bureau of the Ministry of public security came to talk with me. We judged This is the enemy's sabotage of the state's key projects. During the NPC and CPPCC, this problem occurred. You can see that today, the three of us, who do you suspect, who is dissatisfied with our country, people around you, who are dissatisfied with the school, who are dissatisfied with you. I was the dean of the Department at that time, and I immediately denied it. I said that it was not because of this, but because of technical problems. At that time, the lead-acid electricity Pool, there is something wrong with our auxiliary battery. The iron wire and the positive wire are tied together. This is the biggest problem. At that time, this problem occurred, but the project is about to be accepted, but there is nothing. What should we do about the project? The test report is gone. The key is that the car is gone. How to check it? If I don't accept it on May 30, the eighth five year plan project will be blacklisted, and I won't be able to serve as a national task any more, which is a very serious problem. I was very anxious at that time. I thought about one day and one night, and I got up the next morning, and I said that I would put together another one, and I would make three cars from March 15 to May 15, and I would finish the experiment on May 25, and I would accept it on May 29. At that time, everyone felt that It's impossible. You've had a car for three years, now it's two months. Including the director of our automobile department, who called me and said, academician Chen is a natural and man-made disaster, not a man-made one. You can't do it. I said I have to fight again. He said that if you do it, I will be the leader of the inspection team, and I will do nothing. In the next two months, we seldom slept, and all the people kept working until May 15, when we made three cars, each car had to run 1000 kilometers, and then we did the performance experiment. On the 25th, all the experiments were finished. At that time, the Ministry of education participated in the on-site acceptance. On the 29th, director Zhang attended the acceptance meeting in person. Fortunately, after that, the National Commission for Discipline Inspection said that Tsinghua also seemed to have It's very good. On the 29th, we finished the inspection and acceptance. On the 30th of May, we reported the report and drew a short period. But it's still OK, so I have a few points today.
One is the state's support policy for the new energy automobile industry. Yesterday, a meeting was held in Changsha, briefly to give you confidence. At the global new energy automobile conference held in Boao on July 2 this year, our country's top leader said that with the rise of a new round of scientific and technological revolution and industrial change, the new energy automobile industry is entering a new stage of accelerated development, which not only injects strong new energy into the economic growth of all countries, but also helps to reduce greenhouse gas emissions, cope with the challenge of climate change and improve global health As for the environment, China adheres to the path of green, low-carbon and sustainable development, and is willing to work with the international community to accelerate the technological innovation of new energy vehicles and the development of related industries, so as to make greater contributions to building a clean and beautiful world and a community with a shared future for mankind.
The second minister of the Ministry of industry and information technology said on September 20 that the national strategy for the development of new energy vehicles should not be wavered, and the integration of vehicles, energy and communication industries should be accelerated. We should not regard new energy vehicles as electric driven vehicles, which is absolutely not the case. We have a strategy. In addition, according to the people's daily, the development of new energy vehicles should have achievements one step at a time and challenges one step at a time. By the end of 2020, all subsidies will be withdrawn, and new energy vehicles will enter a new stage of structural adjustment and power conversion. Vehicle enterprises need to face the challenge of market reshuffle, which is an important issue. In addition, when subsidies decline, innovation needs to go up. Every time technical innovation goes further, safety assurance must go up to a higher level. Driving safety is the top concern of consumers, which is clearly stated by the state. With regard to the safety of new energy vehicles, Boao, in consultation with Director Wang of the Quality Development Bureau of the State Administration of market supervision and administration, comprehensively introduced the work of vehicle defect recall. A total of 123000 new energy vehicles were recalled, but he stressed that there is no evidence that the risk of electric vehicles is greater or more unsafe than that of fuel vehicles, and the risk of electric vehicles is controllable. The recall is mainly due to the three electric functions The recall is caused by faults, of which 40% are caused by design, 60% by manufacture, 56% by vehicle in stop state when the fire is on, and 37.3% by charging process. The solution is to strictly monitor and protect the safety of consumers, and at the same time to promote the development of new technology, new materials and new industries, which is a key problem. In addition, the reliability of 415000 Nissan Lingfeng electric vehicles is very high, which ensures that there is no record of major traffic accidents. The main reason is that some of its designs and experiments are well done. Even when the Fukushima earthquake occurred in 2011, more than 20 vehicles were submerged by the sea water, and no fire occurred. The safety of new energy vehicles is designed, carefully manufactured and strictly tested The result of maintenance can ensure the safety of new energy vehicles with the completion of four links. The safety problem is a comprehensive problem, from design, manufacturing, testing, certification to maintenance, which is a very important problem.
The power battery is the key of new energy vehicles, and the power battery is its core. There are three levels of batteries: a single cell, a battery module, and a battery pack. Now some people say that the batteries without modules can be used directly, but now this is just an idea. A large number of high-precision intelligent production methods are carried out. The battery modules and battery packs are basically vehicle manufacturers, According to the performance, layout and various requirements of the whole vehicle, the battery pack is composed of mechanical design, shape, strength, rigidity, sealing, dustproof and waterproof, collision safety, electric quantity management, electromagnetic compatibility, and battery thermal management, including thermal fluid and heat dissipation, which are important barriers for battery safety. Therefore, the battery pack is very important for safety It has a great effect on the efficiency of the battery.
We can see that there is a thing in Tesla's battery, which is liquid in the middle. The thermal management includes the circulation system at room temperature to dissipate heat from each single battery. This system is well designed, but it is difficult to achieve success or failure. How to industrialize and mechanize this system? The reason why Tesla's capacity can't keep up with this is that It doesn't work. According to my students, this system costs nearly 10000 US dollars in labor cost in the United States. More than 8000 batteries are connected with things inside. It has to make a 180 degree turn. It can't shrink. It's very thin. 0.8mm is very difficult to process. In addition, this system includes three kinds of electric vehicles, i.e. pure electric vehicle, plug-in hybrid vehicle, and power battery. In addition, this is fuel cell. The actual fuel cell is called power transformation hybrid, fuel cell add-on program. There is a relatively large power transformation group. We first proposed this program. We introduced Benz company in 2008 Olympic Games It's just a fuel cell. We are 80 fuel cells. When the fuel cell accelerates and climbs, it can use batteries. When the braking energy is recovered, when it's idling, the fuel cell continues to generate power. This performance is the best. At present, this system is used all over the world, which is made up of batteries. The plug-in hybrid must be a battery, which is a system called add-on program. In fact, add-on program is also a series type to expand the battery pack. The battery is the most critical part of new energy vehicles. Whether it is pure electric, fuel cell or hybrid, plug-in power batteries and general hybrid power are also available. Now the price has been reduced to one dollar per watt hour. During the first 15-year plan period, the price was four dollars per watt hour, which is higher than the energy. Now the price of single cell can be raised to more than 200. The fuel cell is developing rapidly. The research and development of lithium-ion power battery technology, from cobalt lithium and manganese acid lithium, has now reached three yuan. Now the main used 532 and 622, high tweezers 811, are relatively high, so the power The development of battery still has to be fast, but there are still several problems. The first problem to be solved is its life span, how many times it can be used, the second one is safety, its diaphragm and its electrolyte are all to be re matched.
In addition, the requirements of the automobile for the power battery are higher than the energy and faster charging. This is a development speed, and the specific energy is indeed increasing. In 2018, the specific energy of the single unit will reach 260 in 2019 and 300 in 2020. The battery capacity and energy density should be improved. The cycle life and thermal management should be considered. The whole safety life performance is related to the design and manufacture of the battery pack. The system structure design of the battery pack, the thermal isolation design of the battery pack, the fire extinguishing design of the lithium battery, the explosion-proof design of the battery pack and the structural design of the battery pack are still very important. In addition, as for the issue of lightweight, it is not allowed to take up too much weight, such as strength, rigidity, tightness, and light weight. Therefore, this is a key issue, and a lot of work needs to be done. To open the mold, we need to work closely with the vehicle factory and battery factory. The problem of the battery is that the heat is out of control, which will definitely generate heat during the operation of the battery. If the heat is not timely and everywhere, it will produce superposition effect After a battery loses control of heat, it may cause explosion and fire. Therefore, the content of ternary materials and nickel increases. The factors causing the loss of heat include the trigger of overheating, the trigger of overcharge, internal short circuit and mechanical trigger. Through the design of heat management system and battery management system, the occurrence of loss of heat can be prevented in the structural design. I found this problem in 2000. When one of my doctoral students was setting up the project, I said that you could simply run out of control of battery heat. When one of my students was doing the experiment, he charged the NiMH battery and started to spray fire. What did the student say? I said that this was a small battery pack. If you went to get a fire extinguisher, we would run away. Then my doctoral thesis started. I said that you can do this. The doctoral students came to me after a week. This question can't be done. I searched the Internet and couldn't find any reference materials. That's the best student in our department. I said to give you two choices. One is to summarize the previous thesis and graduate with a master's thesis. Second, you can see what you can do to meet the doctor's qualification Ge, and I can guide you. It's not my business for you to engage in cancer and aerospace. I say you can take a look at two ways. One is that you leave my research group, and the other is that you just write a report and quit. You have been studying for two and a half years as a direct doctor, and you can finish your master's degree in another half a year, because he thinks it's disgraceful, and he is determined to go ahead. In 2005, when the topic was made and anonymous evaluation was issued, many domestic experts commented on a C, saying that it was a false proposition. He was wrong to engage in thermal management. At last, the student cried with that thing. I said that he didn't mean you, but me, and I came out with this topic. Although I don't know who that person is, he must be an expert in lead acid. I said you sent it to the 863 expert group I went to the review office and later called me to say that this article was very good. Later, another doctoral student of mine went on to further study, but it's a pity that both of them are now in politics. The last doctoral student graduated in 2012 is now the Secretary of the county Party committee, so I feel that this problem still needs to be studied.
The management system of power battery is really very complex, including electric management, thermal management and various problems. We should pay attention to these problems, and do it from the aspects of mechanical design, electrical design and thermal fluid. Now there is another problem. Our national standard of single battery is very complete, but the standard of battery pack is not very complete. I was originally from the electric vehicle standard committee Deputy director, now as a senior consultant, I just have the right to make suggestions and work out the standard of battery pack. This is my second question.
At the end of my speech, the safety of new energy vehicles and batteries is very important, which is related to people's life safety. The power battery is the core of new energy vehicles. Correctly handling the relationship between safety, reliability, performance and cost is the foundation of the development of power battery production capacity. The power battery of new energy vehicles is designed, carefully manufactured and strictly inspected As a result of real maintenance, the safety of new energy vehicles and battery packs can only be maintained if these indispensable environments are well done. In the further development of the automobile industry, it is necessary to put technology research and market research first, share professional manufacturing, and promote the innovation of technology management system and mode. Today, I will talk about these issues. We still need to pay attention to battery packs. Now let's see To this problem, but from the administrative point of view, from the technical point of view, especially in the design, in the manufacturing, in the detection, in addition to the timely development of maintenance specifications, otherwise in a few years, the situation is very good at the beginning, in a few years no one to maintain the battery pack, there must be a problem, may not be the current fire, more serious than now, may arrive There are more fires in summer, because some batteries have aged. If they are not handled in time, there may be problems. I am not sure what I said above is right. Please criticize and correct. Thank you.
