In the hydrogen fuel cell industry chain, the upstream is the preparation, transportation and storage of hydrogen, and the hydrogen fuel cell system injects hydrogen at the hydrogen refueling station; In the production of key components such as the middle reaches of the stack, the stack and accessories are integrated to form a hydrogen fuel cell system; At the downstream application level, there are three main directions: transportation, portable power supply and fixed power supply; The consumer terminal is the production and sales of battery cars.
Fuel cell stack
Fuel cell stack is the heart of fuel cell automobile industry, and its cost accounts for more than 60% of the cost of fuel cell system, so the technical threshold is high.
Fuel cell stack is mainly composed of catalyst, proton exchange membrane, gas diffusion layer, bipolar plate and other structural components such as seals, end plates and collector plates.
The domestic fuel cell stack industry chain has begun to take shape, with complete upstream manufacturers, membrane electrodes, proton exchange membranes and bipolar plates with localization capabilities, gas diffusion layers supplied in small batches, and catalysts with research and development capabilities.
Compared with foreign fuel cell stacks, domestic fuel cell stacks still have shortcomings in core materials and key technologies, which is also the main reason for the high cost of fuel cell stacks. Therefore, reducing the cost of fuel cell stack is still the key to the commercialization of fuel cell vehicles.
Fuel cell structure: membrane electrodes and bipolar plates are stacked to form a stack.
Bipolar plate: the "skeleton" in the battery stack
Bipolar plate is the "skeleton" in the stack, which is formed by stacking membrane electrodes. Bipolar plate plays the role of supporting, collecting current, providing channels for coolant and separating oxidant and reductant in fuel cell. Its performance will directly affect the volume, output power and life of the stack.
Bipolar plates are mainly divided into graphite plates, metal plates and composite plates according to materials.
At present, graphite plate is the main technology in China, and metal plate is the mainstream technology in the future. Commercial vehicles tend to be equipped with graphite plates, while passenger cars are equipped with metal plates because of their high space requirements.
Graphite bipolar plate
Graphite bipolar plate is the most widely used material in proton exchange membrane fuel cell (PEMFC) at present, which has good electrical conductivity, thermal conductivity and corrosion resistance, and is often used in the field of commercial vehicles.
At present, graphite plate is mature in technology and commercialization, occupying a large market share, and it is difficult to further reduce the cost. With the development of the industry, it is necessary to wait for the cost reduction brought by the technological upgrading of upstream graphite materials to stimulate demand.
The thickness of graphite bipolar plate is about 2 ~ 3.7 mm, and it is processed into a certain shape of diversion liquid tank and liquid channel by milling machine. The design and processing technology of the liquid channel are closely related to the performance of the battery.
The technical barrier of graphite bipolar plate is low, and foreign representative enterprises include Poco in the United States and Ballard in Canada. Domestic technology has reached the international first-class level. Representative enterprises include Shanghai Li Shen (Yihuatong Subsidiary), Shanghai Hongfeng, Zibo Lianqiang, Shanghai Hong Jun and Guo Hong Hydrogen Energy, among which Shanghai Hongfeng products have been exported overseas. Guo Hong hydrogen energy graphite bipolar plate technology is mature and can be mass-produced and customized. _
Image source: official website, Li Shen, Shanghai
Metal bipolar plate
Metal bipolar plate is easy to be corroded, but it is small in size, short in production cycle and easy to be mass-produced quickly, so it can be used in the field of passenger cars. Foreign representative enterprises include Dana in the United States and Honda in Japan.
Metal bipolar plate will be the future development direction. Enterprises that take the lead in mastering domestic mass production of metal plates are expected to seize the opportunity in the fuel cell passenger car market. Domestic representative enterprises include Shanghai Zhizhen, Shanghai Ge You, Xinyuan Power and Chery Automobile.
Shanghai Zhizhen can realize the localization and mass production of bipolar plates, and the designed annual output can reach 500,000 pairs, which can be used by at least 1500 FCV, and has supplied SAIC Jiehydrogen metal plate stacks in small batches.
Composite bipolar plate
Composite bipolar plate has both the corrosion resistance of graphite and the high strength of metal, and the effect is the best, but it has not been widely used because of its complicated processing and high cost.
On the whole, the domestic substitution of bipolar plates has developed to a certain level, and in the process of technology switching from graphite bipolar plates to metal bipolar plates, the comprehensive domestic production has been gradually realized. Domestic manufacturers such as Xinyuan Electric Power, Wuhan Himalayan Optoelectronics, and Hydrogen Chuangneng have R&D capabilities.
Membrane electrode: that core of fuel cell technology
_ Membrane electrode and bipolar plates on both sides constitute the basic unit of fuel cell.
Membrane electrode is the core component of fuel cell stack. As a place of chemical reaction, it consists of catalyst, gas diffusion layer and proton exchange membrane.
The membrane electrode assembly is formed by placing two carbon fiber paper electrodes sprayed with Nafion solution and Pt catalyst on both sides of the pretreated proton exchange membrane, so that the catalyst is close to the proton exchange membrane and molded at a certain temperature and pressure.
catalyst
In the fuel cell, the catalyst plays the role of decomposing hydrogen and oxygen for electrochemical reaction to generate current.
At present, the catalyst for commercialization is platinum-carbon catalyst, and the high cost of rare metal platinum is one of the main obstacles to the commercialization of fuel cells.
The amount of external catalyst is realized.
The three giants of global catalyst manufacturers are German BASF, British Johnson & Johnson Feng Wan and Belgian yomi Branch, with a global market share of about 90% and a domestic market share of about 70%. It has been able to realize mass production (more than 10kg/ batch), with stable performance and high reliability.
Domestic catalyst manufacturers, including Guiyan Platinum, Zhongzi Technology, Huachang Chemical, Shanghai Tang Feng, Wuhan Himalayan and Shanghai Jiping New Energy, are also engaged in research and development of related products.
Proton exchange membrane
Proton exchange membrane is located at the end of organic fluorine chemical industry chain. Its upstream is the monomer material of organic fluorine chemical industry, and its downstream is chlor-alkali industry, fuel cell, electrolytic water, energy storage battery based on proton exchange membrane and other application fields.
Proton exchange membrane is the core component of fuel cell, and its thickness, chemical stability and proton conductivity directly affect the comprehensive performance of fuel cell, so it has high requirements for the performance of proton exchange membrane.
There are mainly DuPont, Comu, Dow, 3M, Gore, Belgian Solvi, Asahi Glass, Asahi Kasei, and more than ten domestic companies such as Dongyue Group and Pan Asia Micro Drive.
China Dongyue Group has a complete industrial chain of perfluorosulfonic acid resin, and its domestic market scale is second only to Gore and Comu. It owns the whole industrial chain of raw materials, intermediates, monomers and polymer membranes, and has built the only production line of perfluoroacid proton membrane resin synthesis in China. At present, mass production and mass production supply have been realized.
Working principle of fuel cell stack;
Gas diffusion layer
The gas diffusion layer (GDL) is located between the gas flow field layer and the catalytic layer. It is composed of carbon paper and waterproof agent PTFE, and plays an important role in supporting the membrane electrode, collecting current, conducting gas, and controlling reaction water (gas) and heat.
Source: National Public Telephone Company.
Overseas enterprises have achieved mass production with mature technology. Foreign manufacturers such as Toray and Mitsubishi, Sigri and Feudenberg, AvCarb of the United States, JNTG of South Korea have all achieved large-scale production of gas diffusion layers, and all have a variety of products suitable for different application scenarios.
At present, the domestic gas diffusion layer technology is still being explored, and the laboratory technology of carbon paper materials can benchmark some international advanced products, but there is still a certain gap in realizing the large-scale production of products.
The well-known gas diffusion layer enterprises in China mainly include Antai Technology, General Hydrogen Energy, Jiangsu Hydrogen Power, Jiangsu Qingneng, Shanghai Hesen Electric, etc.
The BOP is the key environment for the stable operation of the BOP stack.
Corresponding auxiliary equipment (BOP, BalanceOfPlant) is the key environment for the stable operation of the stack.
From the overview of Toyota Mirai fuel cell system, it can be clearly seen that the BOP component of the fuel cell system provides the necessary external environment for the stack, and the orderly organization and cooperation of hydrogen flow, air flow and condensate flow is an important factor for the stable operation of the stack.
For BOP, its cost composition is relatively dispersed, and the air compressor and motor are some core components of the gas circuit.
Overview of Mirai fuel cell system:
Air compressor: the core component of fuel cell system _
Fuel cell air compressor can greatly improve the performance of the stack. There are many kinds, among which centrifugal compressor has a good comprehensive effect in density, efficiency and noise, which is the main development direction.
As far as localization rate is concerned, air compressor is the key component of fuel cell with high localization degree in China.
According to the statistics of Yin Shi, compared with other auxiliary system products, the air compressor realized the localization of full power section earlier, and the localization rate is close to 100% at present.
In recent two years, the suppliers of fuel cell air compressors in the domestic market mainly include Yeti, Shi Jia Toubo, Kingston Technology, Pingli Technology, Yantai East Germany Industry, German combustion power, ice wheel environment and other enterprises.
Installation market structure of fuel cell system
Generally speaking, the installed capacity of hydrogen fuel cells in China has increased rapidly in recent years. At present, there are many regional orders in the market, and there are more and more competitors who supply in bulk. Market competition has been increasing, and market concentration has been decreasing year by year. In 2020, the CR5 will be 64%, which is 65,438+04% lower than that in 2065,438+09, and it is expected to decrease in 2-3 years.
In 2020, the TOP3 installation share of fuel cell vehicle engine system will be 16. % in Edelman, 15. % of Yihuatong, 65,438+02% of Guo Hong reconstruction.
Thanks to the accelerated localization of core materials and key components, the prices of fuel cell systems and stacks in China have been reduced by 30%-50% in 2020.
In the next few years, with the scale of domestic core components and the intensification of competition, it is expected that the price of stack will drop at a rate of 25%-30% every year in the next few years.
At present, China's fuel cell industry is developing rapidly, but it mainly focuses on vehicle assembly and demonstration operation, and there are few core technologies such as stack, membrane electrode and bipolar plate in the industrial chain.
From the technical indicators of fuel cell power system integration, environmental adaptability, reliability and life, cost control, hydrogen storage and so on, the domestic level is far from the international level. At present, domestic independent R&D and foreign mature technology manufacturers coexist, but the material properties and output of key components need to be improved urgently.