According to data from the Passenger Federation, the output of narrow passenger vehicles (ie sedans, SUVs, MPVs) in China in August 2018 was 1.675 million, down 5.2% year-on-year and 0.7% month-on-month; cumulative production from January to August was 14.99 million vehicles , An increase of 2.1% year-on-year. Sales volume was 1.734 million vehicles in August, down 7.4% year-on-year and up 11.1% month-on-month; cumulative sales from January to August were 14.274 million vehicles, up 1.3% year-on-year. The promotion and application of new energy vehicles is in a critical period. With the continuous promotion of promotion and application and the continuous expansion of market application scale, the safety of new energy vehicles should be paid more attention. To

According to incomplete statistics, there were 10 electric vehicle fire accidents at home and abroad in the first half of 2018, including 8 domestic fire accidents and 2 foreign fire accidents, an increase of 1 from the same period last year. In recent days, news and videos of the spontaneous combustion of electric vehicles have appeared in major WeChat groups. Weimar spontaneously ignited, Tongling bus caught fire, and Foshan public bus caught fire while charging. Lifan EV650 went on to "fire" and became a domestic new energy source. The spontaneous combustion incident of a certain brand of automobile leader in Fujian continued to ferment, once again pushing the safety of power batteries to the forefront of public opinion, and people cannot help but wonder whether lithium batteries have become the shackles of the development of new energy vehicles?

The reason for dismantling spontaneous combustion electric vehicles has nothing to do with the level of battery manufacturing

Why do electric cars catch fire? Is the current technology level of car companies unable to prevent it from catching fire or is it because car companies have not invested enough money in preventing fires?

According to a fire department's summary, there are four main scenarios for burning new energy vehicles: burning during charging; burning caused by battery driving or placing; burning caused by collision and overturning; burning caused by wading. Among them, burning during charging is the most common. Compared with the explosion when charging mobile phones, during the charging process of electric vehicles, if any one of the three links of battery core, BMS, and sensor is not matched, spontaneous combustion may occur.

First of all, every battery has a different "physique". It is specifically manifested in professional parameters such as internal resistance, self-discharge rate, attenuation rate, and polarization. Although professional and technical personnel will group the "physique" of the battery to reduce the difference between the cells, the "physique" of the battery, like a person, will change with the use of time. Good quality batteries have relatively small differences in "physique". To achieve this, the consistency of the selection of materials should be good, the automation level of the production process should be high, the quality standard should be high, and the cost should be high. Conversely, poor-quality batteries have low cost and large individual differences, and there are great safety hazards.

Because of the inconsistency of the battery cells, other things need to be involved in the overall management, so the intervention of the BMS responsible for the battery management strategy is particularly critical. And if the BMS malfunctions, or even a brief crash, the consequences are much more serious than the malfunction of the mobile phone. What to do when this happens, is there a second battery management solution that can be backed up? I believe that when there is an "emergency device" in the system, the system is bound to be more secure, but it will also increase the cost.

The management of the battery by BMS must first grasp the information of the battery, which requires sensor monitoring to achieve. The more sensors, the higher the accuracy of the sensors, the more comprehensive the feedback data, and the more accurate the judgment of the BMS on the battery. However, correspondingly, the cost is higher.

Therefore, from the above analysis, it can be seen that under the background of car companies advocating cost reduction and maintaining profits, reducing the cost of automotive electronic components, especially power batteries, may be the source of harm. Blindly pursuing the maximization of commercial interests, the price to be paid may be passed on to consumers to pay the bill.

The Ministry of Industry and Information Technology requires self-inspection and puts pressure on enterprises to ensure safety

The concentrated outbreak of fires one after another has also attracted the attention of the Ministry of Industry and Information Technology. In order to ensure the safe operation of new energy vehicles, ensure the safety of people’s lives and property, and promote the healthy and sustainable development of the new energy vehicle industry, in accordance with the Ministry of Industry and Information Technology "Notice on Further Doing a Good Job in the Safety Supervision of the Promotion and Application of New Energy Vehicles" ( Ministry of Industry and Information Technology (2016) No. 377) and the Ministry of Finance, the Ministry of Industry and Information Technology, the Ministry of Science and Technology, and the Development and Reform Commission "Notice on Adjusting and Improving the Financial Subsidy Policies for the Promotion and Application of New Energy Vehicles."

Among them, the Ministry of Industry and Information Technology requires that the investigation of potential safety hazards be carried out on vehicles with IP protection failures, vehicles in water, vehicle collisions, loose wiring harness connections, frequent charging and discharging or long-term shelving. Among them, vehicles used with high intensity should be set according to the driving mileage. , The proportion of self-examination for driving under 80,000 kilometers is not less than 10%, the proportion of self-examination for driving 80-200,000 kilometers is not less than 20%, for driving 200,000-300,000 kilometers is not less than 30%, and the proportion of self-examination for driving more than 300,000 kilometers is not less than 10%. Power batteries that have many faults in use (such as Waterma batteries) should be fully inspected. The full inspection shall be combined with the previous situation, and the company shall decide whether to open the box for inspection. The inspection should include visual inspection, software diagnosis, air tightness inspection, unpacking inspection, replacement and capacity testing of the power battery (see Annex 1 for details). The self-inspection work can be carried out in conjunction with the maintenance of the vehicle. For vehicles that are found to be problematic, they should immediately organize personnel to take all measures to deal with them in accordance with laws and regulations to eliminate potential safety hazards.

Academician Yang Yusheng: Pay attention to the development of lithium iron phosphate batteries and develop safe electric vehicles

Among the many new energy models, my country has the highest subsidy for pure electric vehicles, and the subsidy is linked to pure electric mileage, so there has been a "man-made ternary wind" in my country in recent years. One-sided pursuit of the guidance of pure electric long-range policy subsidies, a new energy car company that has always insisted on "iron batteries" has also been fascinated. After losing the first seat of domestic batteries, it has become a follower for fear of falling behind. ".

Yang Yusheng, an academician of the Chinese Academy of Engineering, emphasized on many occasions that continuously increasing the specific energy of batteries is a very dangerous way. He said that in order to obtain subsidies, some battery companies put energy density in the first place in product development. In order to increase the energy density, the ternary battery cathode material system is moving from 111, 523 to 622, 811 material system, by increasing the nickel content to increase the voltage, but with it, the risk of thermal runaway increases, and the battery safety risks continue. Increase. He believes that the principle of "making good use of mature and safe batteries" should be adhered to to develop safe and energy-saving electric vehicles.

It is undeniable that continuously climbing new heights of energy density not only breaks the key constraint on the cruising range of electric vehicles, but also promotes the technological progress of the entire battery industry. This is naturally the result of development that everyone expects. But as people often say, the steps are too big and it is easy to get stuck. When the production process and battery management system are relatively immature, blindly emphasizing energy density and blindly increasing the nickel content in the ternary battery can easily lead to thermal runaway.

Lithium battery inspection station built in Huizhou, Guangdong to fill the gap in battery testing

Recently, the Guangdong Bureau of Quality and Technical Supervision conducted on-site acceptance of the Guangdong Provincial Quality Supervision Automobile Lithium Power Battery Inspection Station (Huizhou), which was built by the Huizhou Quality Metrology Supervision and Inspection Institute.

The inspection station has a laboratory area of ​​1,200 square meters, 27 instruments and equipment, and the original value of the equipment is nearly 8 million yuan. The equipment covers high current charge and discharge, mechanical shock test, battery flip test, battery squeeze acupuncture test, electromagnetic compatibility test system, environmental reliability test system, control system conduction immunity test system test system, safety test system, etc., testing Capability covers 9 domestic and foreign standards and 96 test parameters, which can meet most of the test items of automobile lithium power batteries. The test products cover single lithium ion batteries, single lithium ion batteries, lithium ion battery packs, lithium ion battery modules, Lithium-ion battery packs, etc.

The establishment of the automobile lithium battery inspection station is particularly important for Huizhou, filling the blank of Huizhou automobile lithium battery inspection. In addition, this model is also conducive to replication in other domestic cities, and will strongly promote the development, transformation and upgrading of the new energy automobile industry across the country.

The introduction of lithium-ion batteries from consumer electronic products to new energy vehicles is not only a technical choice for power, but also a result of market competition. Even though there are many car accidents at home and abroad every year, it is obvious to all that lithium batteries push cars into a new stage of development.