Electric vehicle safety survey (Part 1)

　　Shenzhen is the city with the highest proportion of new energy vehicles in the world. One out of every 10 vehicles is a green-label new energy vehicle. Recently, two things happened in this city:

　　The first thing happened was that two "blue" (electric taxi) drivers were fined 1,000 yuan for refusing to take the taxi. However, the two drivers stated in the administrative review that the reason for the refusal was because the car had insufficient battery power. The second thing is that the Shenzhen Development and Reform Commission notified the safety investigation of a certain electric vehicle of BAIC New Energy that spontaneously ignited during charging, requiring charging operators to suspend charging services for this model.

　　These two incidents have once again brought to the fore two topics that people are worried about electric vehicles: driving range and battery safety.

　　Is today's electric vehicle battery technology sufficient to handle the large-scale application of electric vehicles? How will new energy electric vehicles develop in the future? In this regard, all media reporters from Guangzhou Daily conducted in-depth interviews.

　　Event: Battery life triggers controversy over "Blue's" fines for refusing rides

　　The endurance of electric vehicles has always attracted much attention. Recently, the news that two taxi drivers were fined 1,000 yuan for refusing to take a taxi due to insufficient battery has also brought the topic of electric vehicle battery life into the spotlight again. The two drivers submitted in the administrative review that they subjectively did not want to refuse the ride, but they had no choice but to let the passengers choose other vehicles because the remaining power of the electric taxi they drove was insufficient.

　　Subsequently, the relevant departments of the Shenzhen Justice Bureau organized a hearing for this purpose.

　　Among them, the driver who was fined was on the evening of the third day of the Lunar New Year this year. He was waiting in line at the taxi platform outside Shenzhen Airport when he waited for a customer who was going to Zhangmutou, Dongguan. At that time, Driver Wang's car battery was at 31%. Considering the insufficient battery and the inconvenience of charging, Driver Wang refused to take the passenger. Finally, after administrative review, it was found that there was indeed a risk that Driver Wang's car would not be able to reach Dongguan or be unable to charge in time after arrival, so Driver Wang's ticket was cancelled. The administrative penalty of another driver surnamed Jiang continues to be maintained, mainly because his electric car has enough power to carry passengers to Zhuhai, and there are local charging facilities for the driver surnamed Jiang to charge and return.

　　Shenzhen is the city with the largest scale and most widely used pure electric taxis in the world. On January 3 this year, the Shenzhen Municipal Transportation Commission announced that all fuel taxis would cease operations and Shenzhen taxis would basically become purely electric. As of May 31 this year, the number of pure electric taxis in Shenzhen has reached 21,115, accounting for 97.30%. However, since this year, in large transportation hubs such as airport taxi platforms, the phenomenon of "blue" drivers refusing to take taxis has increased. The reason given by the drivers is insufficient battery.

　　Battery life and the popularity of charging piles have always been one of the topics that owners of electric vehicles are most concerned about.

　　In order to solve the problem of battery life, in addition to technological upgrades and dense layout of charging piles, automobile manufacturers generally adopt the approach of increasing battery energy density. Higher energy density means an increase in the probability of battery thermal runaway and a decrease in safety. Battery safety has become an unavoidable issue.

　　According to data disclosed by the State Administration for Market Regulation in October 2018, more than 40 electric vehicle fire accidents occurred across the country in 2018. Statistics from the charging pile company’s special call show that from April 21st to May 10th, there were 11 electric vehicle fires. At the electric vehicle safety theme salon held by the "China Clean Transportation Partnership" in January 2019, the theme report at the meeting pointed out that there were 62 electric vehicle safety accidents in 2018, a significant increase compared with previous years.

　　Phenomenon: Battery life and safety have become the focus of both buyers and sellers

　　The battery life and battery safety of electric vehicles are two major concerns of electric vehicle owners and potential buyers; at the same time, they are also two aspects that electric vehicle manufacturers and sellers focus on when selling.

　　At the Shenzhen-Hong Kong-Macao International Auto Show held not long ago, an all-media reporter from Guangzhou Daily found that many citizens were interested in buying electric vehicles. At the same time, they expressed concerns about battery life and safety.

　　This auto show has specially opened a special exhibition for new energy models, and major car companies have showcased their own new energy models. Reporters observed at the scene and found that car salespeople often introduce these two aspects as soon as possible when promoting their own electric cars to the audience.

　　In terms of battery life, the reporter found that the battery life of the foreign brand Tesla is in the range of five to six hundred kilometers, while other brand models are generally in the range of three to four hundred kilometers.

　　As for the introduction of battery safety, all the major participating car manufacturers showed their talents. For example, BYD displayed the "skeleton" of a certain model, with only the wheels and battery and motor parts left on the "skeleton". Viewers can see that the battery is partially wrapped in a very hard metal box.

　　The salesperson said, "The battery has passed various extreme tests such as acupuncture, fire, flooding, collision, etc., and customers can use it with confidence." A salesperson of a Buick electric vehicle said that their early warning system can instantly cut off the battery power supply. , and then completely discharge within 1 second.

　　At the NIO booth, the ES8, which sells for over 400,000 yuan and has a beautiful and luxurious appearance, is very popular, with people constantly coming to experience it or make inquiries. The relevant sales person in charge told the Guangzhou Daily All-Media reporter that the ES8 began to be delivered around August 2018. Within about half a year of sales, the model's sales nationwide were close to 20,000 units, and sales in Shenzhen were close to 2,000 units.

　　In response to the spontaneous combustion and smoke incident of NIO's ES8 that occurred in Shanghai in May, a salesperson told reporters from Guangzhou Daily that the ES8 only smoked rather than burned, and that the car was overcharged. In order to prevent overcharging, NIO has launched a plan to limit the charging capacity using a mobile app.

　　expert:

　　Is the pursuit of endurance leading to the development of power batteries?

　　Ma Yanjun, who graduated from the School of Materials Science and Engineering at Tsinghua University and studied battery thermal management systems, said in an exclusive interview with an all-media reporter from Guangzhou Daily that "smoke" is already the initial manifestation of thermal runaway in power batteries, and burning or even explosion is the follow-up to thermal runaway in power batteries. develop.

　　He told reporters that spontaneous combustion or explosion of electric vehicles is mainly caused by thermal runaway of the battery. If the battery pack accumulates heat and cannot dissipate heat to the outside world, it will easily cause a thermal runaway chain reaction, resulting in spontaneous combustion or explosion.

　　In recent years, companies have been continuously improving battery technology, and the energy density of batteries has become higher and higher. In 2016, the new energy vehicle subsidy policy included battery energy density as an assessment indicator for the first time. The new round of subsidy policies in 2018 further strengthened the energy density threshold of electric vehicle power battery systems and accelerated the elimination of low energy density batteries.

　　Ma Yanjun believes that it is precisely because the energy density of batteries is getting larger and larger, but problems such as thermal reactions inside the batteries cannot be better solved and controlled, thus increasing the probability of thermal runaway in electric vehicles.

　　At an electric vehicle safety themed salon in January this year, Fang Jianhua, partner and president of the New Energy Vehicle Venture Capital Sub-Fund of the National Science and Technology Achievements Transformation Fund, pointed out, “Originally, improving the energy density of the system should be solved through chemical methods. However, in actual situations, physical methods are used to remove the necessary protective measures, such as thermal protection, thermal energy management, fuses, etc.; in order to reduce weight, the thick separators and battery boxes are thinned; and the small ones are removed. The battery cells have been enlarged.”

　　Based on this, experts suggest that policies should not rush to increase battery energy density, but should respect the law of technological development and reserve sufficient verification time for technological upgrades.

　　The future: Solid-state batteries will make electric vehicle adoption smoother

　　Although electric vehicles are currently unsatisfactory, many experts agree that the transition from fuel vehicles to new energy vehicles is a gradual process. With the advancement of science and improvement of technology, electric vehicles will make a qualitative leap in various technologies in the future.

　　Regarding the future of electric vehicles, Huang Xuejie, a Chinese battery technology expert and researcher at the Institute of Physics of the Chinese Academy of Sciences, expressed great optimism in an exclusive interview with an all-media reporter from Guangzhou Daily.

　　Huang Xuejie believes that the key technologies for electric vehicles include battery technology, electric drive and control technology and vehicle technology. Battery is the power source of electric vehicles and a key factor that has always restricted the development of electric vehicles. The specific energy of existing lithium-ion battery systems has exceeded 150Wh/Kg, and 200Wh/Kg battery packs will also be commercialized in 2020. The focus at this stage is to improve lifespan, safety and reduce the cost of mass production.

　　Huang Xuejie said that the range of electric vehicles today, regardless of the energy density of power batteries or charging technology, has been greatly developed in recent years. I believe that with the scale effect, the technology and cost of Sanden will make a qualitative leap. By 2030, solid-state batteries with doubled energy will be commercialized, and the popularity of electric vehicles will be smoother.

　　Huang Xuejie predicted to Guangzhou Daily’s all-media reporters that there will be three trends in the development of automobiles: intelligence, electric and sharing. Electrification and intelligence are combined, and electrification is an inevitable trend.

　　In the 5G era, cars will first become intelligent and become an intelligent terminal integrating intelligent work, life, and entertainment functions. Transportation is only one of its functions. Within ten years this may become a reality.

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