What is the reason for the recent electric vehicle recall triggered a safe concern for the battery for a safe fear of a battery?

　　Author ：Iflowpower – Portable Power Station Supplier

A few days ago, the State Market Supervision and Administration, four announcements, recalled nearly 1.5 million vehicles, involving the Great Wall, Wuling, Chery and other brands. Among them, Chery and Great Wall recall are electric vehicle models, and safety hazards involve power batteries.

Although the Ningde Times is rushing to clear the relationship, there is still no hammer who escapes the stock price. After that, the two power battery suppliers surfaced, and they also pulled the safety issues and current market conditions of the soft bag battery. The recall vehicle battery is a soft bag battery on July 16, Chery Ai Ze 5E 5E and Great Wall Auto Eu IQ electric car released a recall announcement, involving recalling a 12,000-stop vehicles.

It is reported that the battery supplier of Great Wall Auto Euler IQ is Fu Can Technology, Chery Eruid 5E's battery supplier for Jiexi. Gu Guofang, deputy dean of Qingdao Automobile Research Institute, Jilin University, told reporters that "the main products of these two power battery suppliers are soft bag batteries, indicating that the problem of soft bag batteries is quite large. "Public information shows that the existing soft package power battery capacity of JewJV has exceeded 3GWH, including Changan, Chery, Dongfeng and other domestic new energy passenger car companies.

As the power battery installed TOP10, the manufacturer of three yuan soft bag batteries, Fu Can Technology as the "First Share of Soft Battery", has landed on the cash on the same year last year. Cao Guangping, a new energy vehicle independent researcher, in an interview with the "China Automobile News", said that the advantages of soft bag batteries are high energy densities, and the shape can be customized, and it is more flexibly suitable for the development of different battery pack envelopes; It is easy to form partial hotspots inside the battery cell. In the case of frequent high current fast charge, the consistency of each of the batches is slightly poor, and it includes a slightly complex process, the sealing process is difficult, and the yield is slightly low.

The reporter learned that the soft bag battery uses an aluminum film film as a package housing, while the cylindrical and square battery housing mainly uses metal materials. Gu Guhong told reporters that the problem of soft bag batteries is determined by the structure of the soft bag battery itself. In addition to the soft bag problem, it is difficult to solve the problem.

Soft bag battery market share needs to be improved Safety and cost has become the main concern that China's new energy vehicle market power battery is about 64GWH in 2020, including 50.88 gWh, 9.20GWH and 3.

93GWH, respectively, corresponding market share, respectively, corresponding market share 79.5%, 14.4% and 6.

1%. From this point, the domestic power battery installed is mainly based on square batteries, and the soft bag battery market has less than 10%. However, for soft bag batteries, car companies have a favored heat of it.

According to Hua'an Securities Research, 15 of the European Hot TOP20 in Europe have selected soft bag technology lines, and the global recognition and usage rate will continue to improve. Cao Guangping said that the universal disadvantages of soft bag batteries and specific battery companies have two levels of problems. Battery security is a system engineering, and the packaging form is just one aspect, the electrode and the electrolysis layer material system and characteristics have a greater decision on battery essential safety.

The reporter learned that Fu Can Technology has a cumulative installed capacity in the first half of this year, which accounts for 1.5% domestic installed, located in Section 8. As a faucet enterprise of a soft bag battery, Fu Can Technology has been caught in Shanqi new energy recall in March this year.

This time, it is quite a lot in the outside world. As of July 19, Fu Can Technology has been involved in the Great Wall Motor "Recall" style, the stock price fell 4.54% to 34.

1 yuan, the total market value is 36.51 billion yuan. Secretary-General of Zhongguancun New Battery Technology Innovation Alliance, Bailian Chamber of Board said in an interview with "China Automobile News" reporter, since 2018, in the domestic power battery sector, soft bag battery share does show downward trends, one is safety The concerns are concerned, and the second is the cost of the aluminum-plastic film.

It is reported that due to the difference in soft bag route and domestic mainstream routes, some raw materials, production equipment procurement channels are still more single, mainly including aluminum-plastic film, lithium battery production equipment, a small amount of auxiliary materials, etc. The aluminum-plastic film produced by domestic enterprises accounts for only 7% of total demand, mostly dependent on imports. The risk of lithium-ion batteries of lithium-ion batteries determine it is a potentially dangerous chemical power supply from its own chemical characteristics and system.

For the fire of electric cars, Professor Xiong Rui, Beijing University of Science and Technology, said that from 2019 data, 41% of self-ignition occurred in the parking process. There are 4 major failures that will cause battery thermal out of control, including internal short circuits, external short circuits, overcharges and overhang. According to research data, 56% of accidents are caused by internal short circuits in the battery, 16% caused by external short circuits, 18% is caused by overcharge, from the accident, there is no accident because Leading.

For thermal out-of-control, China Automotive Technology Research Center Co., Ltd. Power Battery Chief Expert Wang Fang believes that under the current technical conditions, the thermal out of control of monomer batteries is inevitable.

Therefore, in terms of battery safety protection, there must be timely monitoring, which is the signal of thermal out-control monitoring. Wang Fang said, we certainly hope that the battery will not be out of control, and there will be no overall spread. But once it diffuses, the time left to the escape is no more than 10 seconds.

In the case of existing conditions, since the heat loss is inevitable, we urge to demand a chain effect that the material can delay the heat loss. Lithium-ion battery Product safety problem analysis Analysis of lithium-ion battery products After 30 years of industrial development, safety technology has made great progress, effectively controlled the occurrence of side reactions in the battery, ensuring the safety of batteries. However, as the use of lithium-ion batteries is getting wider, energy density is getting higher and higher, in recent years, there is a frequent security injury or recall for safety hazards.

We summarize the cause of the safety of lithium-ion battery products mainly include the following: 1 The materials used in the battery cells include: positive active substance, negative electrode active material, diaphragm, electrolyte and housing, etc., the use of materials and composition The matching of the system determines the safety performance of the battery. When selecting positive, negative electrode active materials and diaphragm materials, the manufacturer does not have a certain assessment of raw material characteristics and matching, causing the innate shortcomings of battery safety.

2 The production process has no strict detection, poor production environment, resulting in mixed impurities in production, not only has a big negative to the battery, but also has a big impact on the safety of the battery; in addition, if mixed in the electrolyte Excessive moisture may have a side reaction, increase the battery internal pressure, affect safety; due to the limitation of production process, the product cannot achieve good consistency, such as electrode matrix The flatness is poor, the electrode active material is falling off, and other impurities are mixed in the active material, the extreme ears welding is not strong, the welding temperature is unstable, the pole edges have burrs and key parts without the use of insulating tape, etc. Safety brings adverse effects. 3 Electrical core design defects, safety performance reduction in structural design, many key points for security have not been valued by manufacturers, such as key parts without insulating tapes, diaphragm design, no margin, lack of margin, positive and negative capacity It is unreasonable than design, and the positive and negative active material area is unreasonable than design, and the extreme ear length design is unreasonable, etc.

, these may be buried for the safety of the battery. In addition, in order to save cost and improve performance, some battery packs are saved and compressed, such as reducing the diaphragm area, thinning copper foil, aluminum foil, and does not use the pressure relief valve, etc. These will reduce the safety of the battery.

4 The energy density is too high. The market is pursuing higher capacity battery products. In order to increase product competitiveness, the manufacturer continuously improves the volume ratio energy of lithium-ion batteries, which greatly increases the risk of batteries.

How to prevent thermal out of control? First of all, it is necessary to prevent the occurrence of flames. The direction of the flame can be directed through the design of the valve body injection direction; also adding a fire extinguishing agent to perform a fire. Of course, the power battery system passes the safety test standard, the probability of the flame has been reduced; at the same time, the power battery system has a good sealing of the battery system insufficient oxygen content, which is not conducive to the generation and development of the flame.

Second, it is necessary to consider the effect of high temperature gas diffusion on other components of battery systems. Some batteries have been able to discharge high temperature gases in time. At the same time, the heat transfer path between the batteries is appropriately barrier, such as a heat insulating layer between the monomer battery.

It should be noted that in thermal management, the battery case may reserve air voids to be fritted, and the adjacent battery is separated. However, during the thermal out-of-control expansion, the thermal out-of-control battery expands, the air gap will disappear due to the expansion of the battery. At this time, the heat transfer between the battery and the battery is still fast thermal, and the method of preventing thermal out-of control is not performed with a simple reserved air gap.

In addition, by reinforcing heat dissipation inside the battery system after the monomer heat loss, the battery around the battery system is enhanced; the battery around the faulty battery is discharged; the heat loss of the phase change material is filled in the battery to suppress the expansion of thermal out-of control. China Auto News, Wing Siwei Terrace Technology.