Why is Tesla Super Battery not suitable for us?

Challenge without limit chasing energy density ratio is risky

“Tesla claims that the energy density of the battery cells is up to 300 watt-hours/kg. The higher the battery energy density, the higher the chance of a fire and explosion accident.” Zhang Yu, secretary general of the Power Battery Application Branch of the China Chemical and Physical Power Industry Association Said that the core of the battery is in the battery management system, although Tesla solved the thermal runaway problem caused by the energy density improvement through the battery system management technology, and successfully avoided the short cycle life of the ternary lithium battery through the car design problem. However, if you want to further increase the energy density, it will pose greater challenges to battery safety management.

Tesla's claimed lithium-ion battery with the highest energy density is not perfect in the eyes of industry experts.

Yang Yusheng, an academician of the Chinese Academy of Engineering, stressed on many occasions that it is a very dangerous road to continuously improve the specific energy of the battery.

Previously, Wan Gang, chairman of the China Association for Science and Technology, had publicly stated that from the market point of view, the driving range is indeed an important indicator of the advancement of electric vehicle technology, but its realization is not simply a matter of increasing the amount of vehicle batteries.

"The greater the energy density of the battery is, the greater the amount of electricity stored per unit volume. The energy density and load of the battery determine the battery life of the electric vehicle. Over the past decade, the increase in battery energy density has mainly depended on the technological advancement of the battery material itself. And the increase in the proportion of active substances in the battery is realized." Yang Xulai, deputy dean of the Engineering Research Institute of Hefei Guoxuan Gaoke Power Energy Co., Ltd., said that by increasing the battery size and reducing the weight of the shell and other auxiliary materials, the battery energy density can also be achieved the effect of the upgrade.

For the new energy industry, which is responsible for the national cornering overtaking mission, the importance of power batteries is self-evident. Many industry insiders admit that power batteries are the heart of new energy vehicles, and how far new energy vehicles can go depends mainly on power batteries.

It is worth noting that according to the "Made in China 2025" power battery development plan: by 2020, the domestic battery energy density will reach 300 watt-hour / kg. Experts believe that China is actively promoting the development of high-energy energy batteries, but the relationship between battery safety and specific energy is still worth studying.

Although the technology has problems, local companies can also produce

According to industry experts, not only is Tesla's battery system control capability, but the design of the entire vehicle is not what most Chinese car companies can imitate and surpass in the short term. So, can Chinese local companies create a ternary lithium battery that is as strong as Tesla?

In the four main materials of the battery - positive electrode material, negative electrode material, electrolyte and diaphragm, the positive electrode material not only accounts for 40% of the cost, but also directly determines the energy density of the cell. According to the technical route of the positive electrode material, the power battery can be mainly classified into three types: lithium iron phosphate, ternary lithium (NCA/NCM) and lithium manganate batteries.

According to the composition of the positive electrode material, the ternary lithium battery is classified into NCA and NCM. NCM means that the positive electrode material is composed of three materials of nickel, cobalt and manganese in a certain proportion and the positive electrode material of NCA is composed of nickel, cobalt and aluminum. Tesla's claimed battery life is a ternary lithium NCA battery.

Zhou Bo, director of the research department of the Power Battery Application Branch of the China Chemical and Physical Power Industry Association, said that the production process conditions of NCA are more demanding and the manufacturing process has a threshold. More importantly, the technical barriers of NCA materials are also very high. At present, the production capacity is mainly concentrated in Japan and South Korea, and China's mass production is less.

"NCA batteries can also be used in China. Last year, a key domestic material company supplied more than 1,000 tons to Japan's Matsushita." Zhang Yu said.

However, according to the reporter's understanding, the industrial development of domestic NCA materials and their batteries started relatively late. At present, many companies have started pilot trials and small batch trial production. There are still some technical problems that need to be solved, and there is no mass production and sales. At the same time, production materials are limited, and the foreign NCA material market is dominated by Sumitomo Metal and Japan Chemical Industry Co., Ltd.

Zhang Yu said that the deep reason for the failure of NCA batteries to be mass-produced in China is that battery safety and battery users have concerns about the safety of NCA batteries due to poor thermal stability. This requires a reliable and safe design of the system from the aspects of battery design, power system design, and power supply. From the processing point of view, NCA batteries require a pure oxygen environment, high processing costs, and control humidity below 10% in the whole process of battery production, which poses great challenges for domestic enterprises.

Based on technology, cost and subsidy factors, China mainly chose the NCM route, but this does not mean that there is no new opportunity for the NCA route.

Cost impact market Tesla may not be the benchmark

Although Chinese local enterprises are not able to create ternary lithium batteries, Tesla's challenge to the limit of ternary lithium batteries is not necessarily the only goal of research and production of new energy vehicle batteries in China.

According to the data from the Power Battery Application Branch of the China Chemical and Physical Power Industry Association, from January to December 2017, the installed capacity of ternary lithium batteries was 16.04 GWh, accounting for 44.01%; The installed capacity of iron-lithium batteries is 17.97 GWh, accounting for 49.29%; the installed capacity of lithium manganate batteries is 1.48 GWh, accounting for 4.06%...

Industry insiders told the Science and Technology Daily reporter that under the leadership of the national policy and the market environment, China's lithium battery technology route is equal to lithium iron phosphate and ternary lithium batteries. However, even in the development of the technical route of the ternary lithium battery, the choice of domestic power battery manufacturers has a focus on the selection of NCM routes, and few choose the NCA route used by Tesla.

NCA batteries have been mass-produced, matured, and commercially proven; and high-energy-density NCM batteries have not yet been mass-produced. Industry experts said that the performance of the two is relatively close, but the high energy density NCM price is slightly cheaper. Therefore, in terms of cost performance, NCM is more in line with the Chinese market.

"In a sense, Lithium Iron Phosphate is actually a new energy vehicle in China. From the perspective of cost, lithium iron phosphate is more dominant. We predict that the future market for lithium iron phosphate battery should be more than the ternary lithium battery." Yang continued to tell the Science and Technology Daily reporter that the current development trend of ternary lithium batteries is due to the national policy-oriented requirements for high-energy energy batteries, requiring high energy density and long range of battery life. Of course, the ternary lithium battery has higher specific energy and specific power, which is more in line with the needs of passenger cars, but it may be not necessarily be the mainstream of the market in the future.

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