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There are risks in the pure pursuit of battery energy density for power 26650 battery

Tesla, which stands at the center of automotive public opinion, is not immune to this, and various spontaneous combustion incidents have been reported from time to time. In addition to the recent frequent safety incidents, the driving range of electric vehicles will also be shortened in winter, which has once again caused consumers to be anxious about the safety and mileage of new energy vehicles.

Ouyang Minggao, an academician of the Chinese Academy of Sciences, previously stated that battery thermal runaway is the main cause of electric vehicle accidents. The main problems are insufficient testing and verification of battery products, deterioration of reliability during vehicle use, and low level of charging safety management technology.

Power batteries seem to be responsible for the frequent electric vehicle safety accidents that have come into people's sight. So, what are the deep-seated problems behind it? To solve the mileage anxiety and win more markets and consumers, how to keep the safety barrier?

The concept of safety first and mileage second is beyond doubt

In the first three quarters of 2018, the total output of new energy vehicles in my country reached 667,000 units, a year-on-year increase of 70%, leading the world. Driven by the new energy vehicle industry, China's power battery industry has maintained a rapid and stable growth trend, the overall market competitiveness has gradually increased, and the cultivation of leading enterprises has been carried out in an orderly manner.

"Safety is the cornerstone of the development of the new energy vehicle industry, and we must continue to pay attention to the safety of power batteries. We must not relax." At the meeting, Gao Junhua, deputy director of the Beijing Work Department of China Automotive Technology Research Center Co., Ltd., admitted that in the past two years, although the new high-energy-density batteries have increased the driving range of electric vehicles, they have also increased safety risks. In fact, every step to improve the energy of power batteries should be based on safety first.

"Electric vehicles and power batteries are interdependent, mutually reinforcing, and mutually restrictive." Yang Yusheng, an academician of the Chinese Academy of Engineering, bluntly stated that the main contradiction of electric vehicles is safety and mileage. Among them, safety is the main aspect of the contradiction, and mileage is a secondary aspect. The two cannot be reversed.

For a long time, the development of electric vehicles in my country has relied more on national policies and subsidies, and has emphasized driving range and energy density, resulting in many things being covered up or even ignored. After the subsidy declines, the real competition is the comprehensive performance of the product.

"The subsidy standards for new energy vehicles in the past two years are closely related to the energy density of power batteries and the vehicle's driving range." Gao Junhua said that the index requirements for the energy density of power battery products have made the product iteration cycle too short, causing some companies to blindly pursue energy density and ignore the optimization of the comprehensive performance of the product. There are situations where local quality is outstanding and the overall chain is unstable, making it difficult to lay the foundation for sustainable development.

The risk of simply pursuing battery energy density is high

The power, economy, safety, reliability, and charging convenience of electric vehicles test the user experience. In Yang Yusheng's view, there are five major anxieties in long-range pure electric vehicles, which seem to have something to do with batteries, specifically mileage anxiety, safety anxiety, charging anxiety, price anxiety, and battery anxiety.

"Only the real progress of batteries can promote the improvement of the level of electric vehicles. If you rush forward, you will suffer. If the battery is not mature, a battery in an unstable state will be used in large quantities in cars, and problems will arise." Yang Yusheng emphasized that the danger of batteries restricts "the arbitrarily increase of electric vehicle mileage."

Deng Zhongyi, director of the Research Institute of Guangdong Mengshi New Energy Technology Co., Ltd., admitted that at present, most of the power battery industry feels very struggling or even difficult. Because the industry has a hard target for the energy density of power batteries: if it does not reach 140 watt-hours/kilogram, the car manufacturer will probably not want your battery. Only after reaching this target can you get a subsidy multiplied by a coefficient of 1.1.

"Everyone pursues energy density as a hard target. Because of this, there are many accidents. Simply pursuing energy density is a very risky thing, which will inevitably sacrifice the safety and service life of power batteries." Deng Zhongyi believes that improving the energy density of power batteries must be meaningful only under the premise of ensuring safety and acceptable cost and life.

Solving safety problems requires starting from the system level

At present, China's new energy vehicle industry is shifting from policy-driven to market-led, and the market competition in the power battery industry is becoming increasingly fierce. Wu Feng, an academician of the Chinese Academy of Engineering and a professor at Beijing Institute of Technology, said that although my country's power battery industry has made remarkable achievements in recent years, it still faces many technical bottlenecks that need to be broken through, such as how to improve safety and driving range, how to achieve long life, low cost, and battery recycling. In addition, there are also realities such as overcapacity of overall battery production, insufficient high-quality production capacity, tension in related enterprises, and a new round of reshuffles accelerating.

"The safety of electric vehicles involves different levels, from materials to battery cells to battery systems, power subsystems, and electric vehicles. What is presented to consumers is the safety of electric vehicles." Long Huijin, chairman and president of Tafel New Energy Technology Group, said that some people now say that the materials are unsafe, and some say that the battery cells are unsafe. We need to solve the safety problem of the entire electric vehicle from a system level. When solving safety problems, we must consider the worst case scenario of other links. Only in this way can the battery cells and materials be the safest.

This coincides with Wang Fang's point of view. Wang Fang said that the safety of electric vehicles is a systematic project. From materials to batteries, each part must have a basic safety requirement. Only by working together as a joint system can we make a better and relatively safe battery system for the whole vehicle, rather than concentrating the safety pressure of a certain part on a certain link.

To this end, Qin Xingcai, Party Secretary and Chairman of Tianjin Lishen Battery Co., Ltd., put forward two suggestions: First, formulate national quality standards for power batteries. Power battery companies should establish scientific and complete quality agreements with vehicle manufacturers, which will not only promote the healthy development of the industry, but also reduce the pressure of after-sales service. Second, battery manufacturers and vehicle manufacturers should work together to strengthen the safety research and management of power batteries throughout their life cycle. The initial safety of batteries does not represent the safety of the entire life cycle. The specifications for new energy vehicle testing should be issued as soon as possible.

"Many of these problems related to the promotion and application of new energy vehicles and power batteries are based on key materials as a breakthrough." Wu Feng said that corresponding new materials should be designed and developed according to the market demand for battery performance. For example, to develop high-capacity, low-cost battery positive electrode materials, we need to start with battery reaction mechanisms and basic materials to conduct research and breakthroughs; to meet the requirements of using new energy vehicles in high-cold and high-altitude areas, we need to start with battery materials and improve the temperature adaptability and reliability of batteries...

Gao Junhua called for the next step that the state's subsidies for new energy vehicles should guide enterprises to meet a certain range of driving, combine the energy density of power batteries, optimize comprehensive performance to make products, reduce costs, and solidify production capacity, and on this basis, subsidies can tend to products with low unit energy consumption, good safety, and long battery life.

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