On the achievement of comprehensive power cell indicators

On April 13, FOURIN's 27th regular meeting of the World Automobile Research Association was held in Beijing. Wang Fang, chief expert of the China Automotive Technology Research Center, gave a keynote speech on the status quo of Chinese and foreign power batteries, and conducted in-depth analysis of domestic and foreign power battery technology and market competitiveness. The paper also puts forward some suggestions on the development direction of power cell technology in China, which should strengthen quality production capacity to reduce blind expansion. Product safety is the first factor.

The 300 W/kg target is expected to be achieved

Wang Fang said that in 2017, the Ministry of Industry and Information Technology issued the "Medium-and Long-term Development Plan for China's Automobile Industry" and proposed that the battery energy density should reach 300Wh / kg in 2020, and the system will strive to reach 260Wh / kg in energy. This is a product indicator and is also the direction of efforts. She believes that the target of 300 Wh/kg can be achieved. The Ministry of Science and Technology has major research and development projects. Some of the products have a single indicator that meets this standard. However, mainstream products in the market are still at 130W/kg-250 W/kg. The level, According to the exchange and understanding of companies, there will be a small number of battery energy densities that can reach 280W/kg this year and can be used directly in cars. However, there are still some problems that need to be solved, such as safety, battery life, and cost. As a loading product, There are still many difficulties to be overcome in the realization of comprehensive indicators.

Wang Fang said that in 2017, the Ministry of Industry and Information Technology released the "China Automotive Industry Medium and Long-Term Development Plan", which proposed that the battery energy density should reach 300Wh/kg in 2020, and the system should strive for 260Wh/kg. This is a product index and the direction of efforts. She believes that the 300Wh/kg indicator can be achieved. The Ministry of Science and Technology has a major special research and development project. Some of the products have reached this standard. However, the current mainstream products are still at the level of 130Wh/kg-250Wh/kg. For the exchange and understanding of the enterprise, this year there will be a small part of the battery energy density can reach 280Wh / kg, and can be directly used in the car, but there are still some problems to be solved, such as safety, battery life and cost, as the installation Car products, the realization of comprehensive indicators still have many problems to overcome.

In the loading data of 2018, the energy density of the battery system was significantly higher than in 2017. The energy density of the pure electric passenger car increased from 107.6 Wh / kg to 118.8 Wh / kg, and the increase rate reached 10.37 <UNK>. The energy density of the battery system from 2015 to 2018 is increasing greatly due to the rapid increase of the single energy density and the Advancement of the grouped technology.

Industry breaking up need to enhance quality production capacity

Worldwide, the industrialization of power cells is mainly concentrated in three regions -- Germany, the United States, China, Japan and the ROK -- while the production of lithium-ion power cells is mainly concentrated in three countries, from the perspective of technology and industry. The country is still ahead of the curve in technology, including solid-state battery research, but it has made tremendous progress in the past two years. The Chinese market share has surpassed that of Japan and the ROK, with the largest number of power batteries and the largest production capacity. The major production areas include the Pearl River Delta, the Yangtze River Delta, the Beijing-Tianjin region and the Central Plains. Battery critical materials, system integration, equipment, recycling and other systems are also growing.

According to data from the Ministry of Industry and Information Technology, in 2017, China's power battery load was 36.7 billion watts, and there were more than 200 battery companies(including battery system integration companies). By 2020, the market demand was about 100 billion watts. Wang Fang believes that At the current growth rate, Battery production capacity will certainly be excessive in the future, but there may also be a shortage of batteries. This is because quality production capacity is still insufficient. Therefore, large companies that have the ability to do so should not only focus on expansion. Only by upgrading quality production capacity can we grab greater market share.

Comparison of Application of Three-way Battery and Lithium Iron Phosphate

In 2017, 224 models of pure electric passenger vehicles were equipped with a total of 199 models with three-way batteries, accounting for 88.8 % of the total, which is a significant increase over previous years because passenger vehicles pursue higher ratios and longer endurance. Commercial vehicles are affected by certain policies. Four of the safety regulations for pure electric passenger cars require thermal runaway experiments. High-to-energy ternary batteries are more difficult to pass this experiment. Therefore, in 2017, passenger cars are basically using lithium iron phosphate batteries.

Wang Fang said that in the evaluation of the models in the market, it was found that the single-unit energy density of the ternary lithium battery was higher, ranging from 136Wh / kg to 230Wh / kg, with an average energy density of 183Wh / kg and a system energy density of 115.4 Wh / kg. The group rate is only 63 <UNK>, The average energy density of lithium iron phosphate monomer is 143.9 Wh/kg, the system energy density is 117 Wh/kg, and the composition rate is 81.5 <UNK>. This contrast is due to the fact that the safety of the battery itself is related to the safety of the lithium iron phosphate battery itself. Compared with the lithium ternary battery, the required thermal insulation, fire protection, heat dissipation, and heat resistance measures are less. Second, the lithium iron phosphate battery is more used for pure electric passenger cars. Passenger car battery box is more than standard box, the design is simpler than passenger car, the additional factor is less.

In terms of cooling methods, Wang said, the CIC compared the cooling methods of 96 models, and the conclusions based on the data compared were not very accurate. Because only 3 of the 96 models tested used air cooling and 7 used liquid cooling. The data comparison showed that the energy density of the power cell using air-cooled was the highest, followed by natural cold and the lowest liquid cold. She explained: This is actually because there are too few air-cooled data. If the same battery system is the same, it should be the highest natural cooling, and then the air-cooled. The second is liquid cooling, because the air cooling and liquid cooling are naturally cooled, the additional components required increase the weight of the battery system and require additional power consumption in use.

However, the safety of the entire vehicle has been improved. At present, companies will use as little air and liquid cooling as possible in order to achieve targets. In the future, fewer and fewer subsidies will be paid to the integrated systems, and there will be greater emphasis on the integrated systems by car companies. There will be potential safety risks in automotive products, and more companies will choose to recall them. This will not only require a lot of financial resources, but also affect the credibility of enterprises. Therefore, safety is the core and foundation of automotive research and development.

Finally, Wang Fang suggested that at the technical level:

1,Safety is the first factor. Safety is still the first factor in the production design of products. We must pay attention to the balance between performance and safety.

2, should further improve the power battery system integration level, so that it can match the speed of development of electric vehicles.

At the industry level:

1, should pay attention to the consistency in the production and use of batteries.

2,We should further improve quality production capacity.

3, should pay attention to the battery recycling and industrial cooperation development.

The page contains the contents of the machine translation.