Tramway News: At the press conference of the State Council New Office on April 19, Luo Junjie, spokesman of the Ministry of Industry and Information Technology and director of the Operation Monitoring and Coordination Bureau, introduced that the mainland new energy vehicles have been promoted by a total of 10.33 million, breaking through the 10 million mark and becoming an important force leading the electrification transformation of the global automobile industry.
In the process of the rapid development of new energy vehicles, spontaneous combustion of vehicles and other problems emerge in an endless stream, in response to these problems, on April 8, the Ministry of Industry and Information Technology, the Ministry of Public Security, the Ministry of Communications, the Ministry of Emergency Management, and the State Administration of Market Supervision jointly issued the "Guiding Opinions on Further Strengthening the Construction of the Safety System of New Energy Vehicle Enterprises" (hereinafter referred to as the "Opinions") to improve the safety level of new energy vehicles and promote the high-quality development of the new energy automobile industry.
Guo Shougang, deputy director of the First Department of Equipment Industry of the Ministry of Industry and Information Technology, said that it is precisely because of the rapid increase in the ownership of new energy vehicles, the risks of their product quality, technical safety and other aspects still exist and gradually expand, so new energy vehicle manufacturers still need to improve the quality assurance body in the product production process.
The relevant person in charge of the Ministry of Industry and Information Technology pointed out that the power battery is the core component of new energy vehicles, and improving the safety of the power battery is the core element.
The "Opinions" clearly pointed out that the safety protection ability of power batteries in collision, vibration, extrusion, immersion, charging and discharging abnormalities and other states should be improved. Encourage enterprises to study the application of thermal runaway real-time monitoring and early warning devices and early suppression and fire extinguishing measures.
In battery safety, thermal runaway is the biggest cause affecting the safety of power batteries, and the accident survey data from 2011 to 2019 shows that the proportion of safety problems in power batteries caused by thermal runaway diffusion accounts for more than 50%.
According to the relevant data of the Fire Rescue Bureau of the Ministry of Emergency Management, there will be about 3,000 new energy vehicle fire accidents nationwide in 2021, and the fire risk of new energy vehicles is generally higher than that of traditional vehicles.
According to the data released by the State Administration for Market Regulation, in 2021, there were a total of 59 domestic new energy vehicle recalls, an increase of 31.1%; involving 830,000 vehicles, an increase of 75.9% year-on-year, accounting for 9.5% of the total number of car recalls in the whole year. Among them, defects in the powertrain were the main cause of its recall.
There are many reasons for thermal runaway, battery pack materials, batteries, systems and the temperature in use is uneven, local area temperature is high, overcharge and over-discharge, external short circuit, internal short circuit and other reasons will be exothermic, in addition to mechanical reasons, such as water ingress, poor sealing, collision and so on.
The country and the industry have long been aware of the risk of thermal runaway batteries, and are actively promoting the safe development of power batteries.
At the beginning of this year, the Ministry of Industry and Information Technology issued the "Key Points of Automobile Standardization Work in 2022", launched the revision of standards related to the safety of electric vehicle power batteries, carried out pre-research on power battery durability standards, promoted the research on power battery electrical performance, thermal management system, exhaust test methods and general requirements for power battery recycling, management specifications and other standards, and promoted the performance improvement and green development of power batteries.
Wu Kai, chief scientist of the Ningde era, said at the 100-person meeting in March that the 8 series battery without heat diffusion in the Ningde era will be called a non-ignition battery after mass production in 2020, and the 1000km endurance heatless diffusion battery will achieve mass production in 2023.
For the Ningde era, because it chose ternary batteries and lithium iron phosphate batteries to develop in parallel, and also pushed its high-nickel ternary batteries, from the perspective of battery materials, the probability of thermal runaway is higher.
In a ternary battery, the higher the composition of nickel, the more active the reaction, the more energy released by the battery, and the greater the energy density brought by the same capacity. Among the three materials of ternary batteries, nickel can increase the battery capacity, the role of cobalt is mainly to stabilize the structure, manganese is not directly involved in the electrochemical reaction, and its role is mainly to reduce material costs and improve material safety. The more nickel there is, the less the other two materials will be.
According to Wu Kai, CATL has improved the 811 battery system in four aspects to solve the thermal diffusion problem: developed a high-stability cathode material and a high-safety electrolyte to improve the battery's high-temperature tolerance boundary; designed a highly integrated, strong and robust anti-internal short-circuit electrode and optimized the strength of the battery pack; improved the monitoring ability in battery thermal management; and improved the thermal diffusion capability of the system.
It can also be seen from the test video released by the CATL era that the technology has achieved results in the laboratory.
The development direction of BYD batteries is to fully convert to lithium iron phosphate, from the perspective of materials, the decomposition temperature of lithium iron phosphate is much higher than that of ternary materials, on this basis, BYD has launched a blade battery, which further improves the safety factor of the battery.
At the meeting of 100 people, Wang Chuanfu proposed to adhere to lithium iron phosphate as the correct development path, one is that the battery is safer, and the other is that the material does not contain rare metals, which can better match the tolerance of social resources.
The "Opinions" released this time once again emphasizes battery safety, and also fully highlights the importance attached by the national competent authorities to this issue, requiring vehicle enterprises as the main body of safety responsibility to start from the vehicle design needs on the one hand, and put forward clear technical requirements to power battery companies, including in-depth cooperation in the design stage, in vehicle matching, thermal management strategies, abnormal state monitoring, and testing and verification. On the other hand, vehicle companies and power battery companies should work together to strictly control product consistency to ensure that batch products meet the safety design goals.