As the 'heart' of electric vehicles, the progress of power batteries has made today's electric vehicles, and it also determines the pace of marketization of electric vehicles in the future. In 2018, the power battery industry entered a fast lane of development, and with the maturity of new battery technologies, The safety of power batteries has gradually become the focus of attention of all parties.
In May, a Tesla Model S in Florida hit a concrete wall and quickly caught fire, killing two high school students and injuring another high school student. In the same month, a Tesla accident occurred in Switzerland. The battery caused the fire, the driver died on the spot... The continuous accident once again pushed the safety of the electric vehicle battery to the cusp of the cusp, and also raised doubts for consumers who are willing to purchase electric vehicles: Electric vehicles, is it safe?
Power battery safety to be tested
The news of the explosion of well-known brand mobile phone batteries has been going on for a long time, but it still leaves many people with a lingering fear. The recent electric car fire accident is even more shocking. Under the blessing of energy saving, high cost performance, etc., electric cars can give everyone peace of mind. Sitting on a big battery and flying?
'The overall technical level of domestic power battery production is still far from the advanced level of foreign countries. 'Inspected by Wang Zhan, an engineer of China Quality Certification Center, the number of domestic power batteries has increased rapidly in recent years. New technologies and new routes are emerging one after another, but the scale of manufacturers is generally not Large, technical strength has room for improvement. Under the current system, the market threshold is relatively low, and some small manufacturers have not yet established a standardized quality assurance system. 'Most companies use semi-automated and automated production equipment in the production process. The product quality level is unstable, and there is still room for improvement in terms of capacity and safety.'
According to the reporter, lithium iron phosphate and ternary lithium batteries are currently the most used power batteries on the market. The data shows that lithium iron phosphate batteries have lower energy density than ternary lithium batteries, but they are better than ternary lithium batteries. Safety. The positive electrode material is the key factor determining the energy density and performance of the battery. The diaphragm is the key material to ensure the performance and safety of the battery. It is well known that the larger the battery capacity, the higher the energy density, the more important the safety.
Academician of the Chinese Academy of Sciences, Professor Ouyang Minggao of Tsinghua University stressed that in the development of electric vehicle power batteries, safety is always the first, and other performance indicators such as energy.
'Influencing battery safety is not only the battery itself, but also related to battery packs, power systems, complete vehicles, etc., especially BMS (Battery Management System). ' Professor Ye Jiping of Tongji University said that the current BMS cannot be like a human nerve. To achieve 'cool and self-aware', all batteries are passively controlled by BMS, and the internal activity of the battery is very large, and it is impossible to see the internal operation under the exposure of the atmosphere, although the material analysis technology is very mature in Japan, Korea and other places. But domestic research has just begun. So people's concerns are not unreasonable.
The battery is safer than you think
Experts in the industry believe that Tesla's fire is caused by the phenomenon of 'thermal runaway' in the collision of the ternary lithium battery, which causes the temperature to rise rapidly.
The same is the car, why do you sit on the petrol car every day, everyone is not so worried; and on electric cars, people are very concerned about safety?
Because the factors affecting 'electricity' are more than gasoline. 'The failure mode of the battery system has five items: electric shock (abnormal power release), combustion, explosion, collision, corrosion. 'Beijing Price New Energy Battery Technology Co., Ltd. Zhang Renbai, vice president, said that battery system safety testing has at least four safety, the first is chemical safety, including material flame retardant, battery safety; the second is electrical safety, including expansion force, sensing, voltage acquisition, temperature acquisition, etc. The third is mechanical safety, such as corrosion resistance, vibration resistance; the fourth is functional safety, such as automatic shutdown of the circuit during the collision process.
'Whether it is overcharge or short circuit, most of the problems are caused by the thermal runaway of the battery. In the future development, we still have to continue to work on stable positive and negative materials. ' Chairman of Fueng Technology (Zhangzhou) Co., Ltd. Wang Wei said that the current common safety measures include fusible fuses, relays, cabinets, batteries, battery modules, liquid cooling systems, thermal management, etc.
Wang Fang, chief expert of China Automotive Technology and Research Center, also stressed that safety is the foundation of electric vehicles. 'Electric vehicle safety is personnel safety. It requires no fire before the person escapes. It does not explode. 'But she also said that the safety of the battery is graded. 'Security is relative, unsafe is absolute. We just want to bring the possibility of insecurity to zero infinitely.'
In addition to technical improvements and rigorous testing, the China National Quality Supervision, Inspection and Quarantine Bureau and the China National Standardization Administration jointly issued the Lithium Ion Power Battery Pack and System for Electric Vehicles on May 15, 2015. Part 3: Safety requirements and test methods (GB/T 31467.3-2015) and other 6 national standards, and fully implemented in 2016. On January 24, 2018, the Ministry of Industry and Information Technology issued the "Request for Solicitation <电动汽车安全要求>Notice of comments on three mandatory national standards (draft for comments). A series of national standards will uniformly enforce battery safety and set a clear 'security bottom line'. Some industry comments indicate that different standards are interlinked and combined. Power battery, module, system and other grade components, is conducive to the healthy development of the power battery industry.
Battery companies, car companies join forces to create a sense of security
Industry experts generally said that the safety of new energy vehicles is not a certain link, but a problem of a certain enterprise, but a system engineering including battery, motor, electric control, vehicle manufacturing, charging facilities, etc. to ensure battery safety is not just a battery. The company's 'incumbent', vehicle companies are even more responsible.
Battery companies, 'need to ensure the safety of power batteries and energy storage batteries from design to production, from use to after-sales safety.' Ningde Times New Energy Technology Co., Ltd. Vice Chairman Huang Shilin suggested.
If the battery company focuses on the research and development of battery performance, then the whole vehicle company pays more attention to the battery use and user experience. The representatives of the vehicle and battery companies said that although the two parties seem to have a clear division of labor, the actual sale does not have to be ' Two clear'. The car company collects data during the user's use, reflecting the user experience and problems. The battery company as a reference can better improve the performance and safety of the battery. Zhang Hailiang, chairman of Zhejiang Dianjia Automotive Technology Co., Ltd. suggested that the whole vehicle Enterprises need to abandon the traditional supply and demand relationship between OEMs and suppliers, and work closely with suppliers to promote the iteration and evolution of battery technology.
Zhang Xiyong, general manager of Beijing Automotive Group Co., Ltd. said that the development of power battery technology directly affects the fluctuations and control capabilities of vehicle manufacturers. The relationship between vehicle and parts is interdependent and common progress, and must be based on industrial development. The height, adherence to the open, cooperative mentality, jointly meet the challenges, and embark on a new path to adapt to the new ecology of the new energy vehicle industry.