18650 li ion rechargeable battery

Foreign 18650 li ion rechargeable battery vehicles have achieved mass production, while my country's automotive 18650 li ion rechargeable battery is still in the technical verification stage

A somewhat embarrassing reality is that foreign 18650 li ion rechargeable battery vehicles have achieved mass production, but my country's automotive 18650 li ion rechargeable batterys are still in the technical verification stage. Wang Haijiang, a professor at the Department of Mechanical and Energy Engineering of Southern University of Science and Technology, pointed out that the current situation of automotive 18650 li ion rechargeable batterys in my country is that there are almost no component manufacturers, no automotive stack production companies, and only a very small number of commercial 18650 li ion rechargeable battery vehicles.

18650 li ion rechargeable batterys are "a team"

Generally speaking, the voltage of a single 18650 li ion rechargeable battery is low and the current is large. In practical applications, multiple 18650 li ion rechargeable batterys need to be connected in series to form a stack to increase the output voltage.

The power sources of hydrogen 18650 li ion rechargeable batterys are hydrogen and oxygen, and the two will start their "fantasy" journey in the 18650 li ion rechargeable battery: hydrogen is oxidized under the catalytic action of the anode to generate protons and electrons; electrons work through the external circuit and reach the cathode; and protons are transmitted from the inside of the battery to the cathode through the proton exchange membrane. Protons and electrons merge at the cathode and react with oxygen under catalysis to generate water.

It seems to be just junior high school chemistry knowledge. But in fact, the operation of 18650 li ion rechargeable batterys is a system engineering.

18650 li ion rechargeable batterys are not like ordinary batteries, but more like generators - they "drink" fuel and oxidant and generate electricity. Therefore, in addition to the battery stack, 18650 li ion rechargeable batterys also have fuel supply subsystems, oxidant supply subsystems, water and heat management subsystems, and thermal management and control systems... In short, they are team specialties.

"18650 li ion rechargeable battery vehicles are a type of new energy vehicle, and it is one of the future development directions." Shao Zhigang, director of the 18650 li ion rechargeable battery Research Department of the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences, told Science and Technology Daily that at the end of 2014, Toyota of Japan announced the commercialization of 18650 li ion rechargeable battery vehicles; in China, everything is still in its infancy.

Key materials are still lacking mass production lines

Automotive 18650 li ion rechargeable batterys are generally proton exchange membrane 18650 li ion rechargeable batterys.

It has two key components, one is called membrane electrode assembly and the other is called bipolar plate. The former is actually composed of "three brothers": proton exchange membrane, catalyst layer and gas diffusion layer.

The main function of the proton exchange membrane is to transmit protons, separate reaction gases and electronic insulation. It is responsible for "guarding the door", letting protons pass and blocking electrons; the catalytic layer is mainly equipped with catalysts, which can promote the oxidation-reduction process of hydrogen and oxygen on the electrode and generate current; the gas diffusion layer is composed of a substrate layer and a microporous layer, which requires high conductivity, thermal conductivity and hydrophobicity.

These key materials determine the life and performance of 18650 li ion rechargeable batterys.

"A good cook cannot cook without rice. Our key materials have long been dependent on foreign countries. Once foreign countries ban sales, my country's 18650 li ion rechargeable battery industry will have no material support." Wang Cheng, director of the Hydrogen 18650 li ion rechargeable battery Laboratory of Tsinghua University, said.

In fact, these materials are not completely absent in my country, and some laboratory results have even reached international standards. However, without mass production lines, the 18650 li ion rechargeable battery industry chain is still blocked. Especially in the mass production technology of gas diffusion layers, my country is still blank. "This is because the graphitization process of the gas diffusion layer requires a high temperature of more than 2000℃ to prepare, but the key equipment high-temperature furnace technology is still in the hands of foreign countries." Wang Cheng explained.

To achieve mass production of materials, we must solve the problems of consistency and cost control. It is not the same difficulty as laboratory preparation. Taking catalysts as an example, Wang Cheng told Science and Technology Daily that the current commercial 18650 li ion rechargeable battery catalysts are still platinum-based catalysts. The laboratory preparation level is generally at the milligram level, and mass production technology requires kilograms. Mass production requires breakthroughs in three key technologies: first, uniform reaction conditions to ensure batch stability; second, control of the nano-size of platinum particles to ensure the specific surface area of catalytic activity; third, improving the stability of carbon carriers to achieve the service life under vehicle conditions.

Industrialization of laboratory results is a key technology that requires the intervention of enterprises. "For a long time, the research and development of 18650 li ion rechargeable batterys in my country has been mainly carried out by universities and research institutes. Enterprises have a wait-and-see attitude, participate less, and join late." The Dalian Institute of Chemical Physics where Shao Zhigang is located has been conducting research on automotive 18650 li ion rechargeable batterys since 1994. However, the gap between basic research and application has made the industrialization of key materials a hurdle.

To commercialize, we must strengthen and supplement the chain

Wang Haijiang returned to China this time, just to bring his years of experience in the field of 18650 li ion rechargeable batterys, and to build a 18650 li ion rechargeable battery industry chain in Shenzhen with his team.

First, there was Nanke 18650 li ion rechargeable battery Co., Ltd., which mainly produces key parts of the stack, integrates the stack and tests the stack. But if the raw materials of the 18650 li ion rechargeable battery stack need to be imported from abroad, the cost is too high. Therefore, the team set up another company to focus on the localization of three key materials: gas diffusion layer, proton exchange membrane and catalyst. "By then, the cost of 18650 li ion rechargeable batterys can be reduced by one third." Wang Haijiang said.

At present, the number of 18650 li ion rechargeable battery stacks and industrial chain enterprises in my country is gradually increasing, and it is expected that the domestic 18650 li ion rechargeable battery stack production capacity will exceed 400,000 kW in 2018. "Pure electric vehicles have made great progress in recent years, creating very good conditions for the application of 18650 li ion rechargeable batterys." Wang Cheng said, "At this time, we need to focus more on the core innovation of 18650 li ion rechargeable batterys."

To break the long-term technology monopoly of developed countries, it is necessary to increase investment in the industrialization of core materials of 18650 li ion rechargeable batterys. The experts interviewed all pointed out that the 18650 li ion rechargeable battery industry chain is "very long", involving hydrogen energy systems, 18650 li ion rechargeable battery power generation systems and automobiles and other terminal products. "Domestic parts, hydrogen infrastructure and standards and specifications are not yet sound. It is necessary to strengthen and supplement the chain to drive the growth of new materials, new energy and high-end automotive equipment manufacturing, so as to promote the acceleration of 18650 li ion rechargeable battery commercialization." Wang Cheng emphasized.

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