Membrane Electrode 2019-09-16 10:58:00 Reading: 121
“Now many domestic entrepreneurs are paying attention to the hydrogen energy and fuel cell industry, from environmental protection and efficiency These advantages are indeed very good in all aspects, and the future is definitely bright, but the road is tortuous," Pan Mu, chief professor of Wuhan University of Technology, said at the 2019 China Automotive Industry Development (TEDA) International Forum.
Where are the twists and turns? Pan Mu believes that there are "three big mountains" on the road to commercialization of fuel cells, namely performance, life, and cost. Nowadays, fuel cells are very expensive compared with pure electric power. However, after more than ten or twenty years of joint efforts by scientists in China and around the world, great progress has been made.
Expensive, just one word
“The power density of the stack has reached 3.1kW/L, which is a relatively good indicator. The indicator corresponding to the membrane electrode performance is per square centimeter. 5.4 watts. If you only count the volume of the bipolar plate plus the membrane electrode, its power density can reach 5.6kW/L. The current technology has reached a very high level. In addition, the amount of platinum used is considered to be the most expensive. , in fact, this catalyst will reach 0.12g/kW from 2006 to 2020, and it can already reach 0.2g/kW. If it reaches 0.12g/kW, it means that each vehicle is equipped with 10 grams of platinum. , and it’s not very expensive. So in terms of performance, thanks to our efforts, the performance of the catalyst, the performance of the stack, and the performance of the membrane electrode can almost reach the industrial level,” Pan Mu said.
According to Gaogong Lithium Grid, Shanghai Hydrogen New Energy Technology Co., Ltd. has developed three generations of fuel cell stacks with independent intellectual property rights after nearly 10 years of continuous research and development. Its 103kW metal plate stack has been tested on the test platform and has a volumetric power density of 3.3kW/L, reaching the industry's advanced level.
Talking about membrane electrodes, Pan Mu said that Wuhan Polytechnic Hydrogen Power Company was established in 2006 to specialize in membrane electrodes. It has now sold 1 million membrane electrodes, most of which are sold abroad. If installed The car can hold more than 3,000 vehicles. Of course, not all of them are installed domestically. They are mainly exported abroad. The foundation of China's parts and components is still very good, and we are still very confident that industrialization can continue.
In terms of cost, Pan Mu estimates that a 100-kilowatt stack costs more than 20,000 yuan, which is based on the core area. There is also a material consumption for structural design, including material utilization, loss rate, and yield rate, which is more than 40,000 yuan, plus 10,000 to 20,000 yuan for bipolar plates, and 100,000 yuan for other things. A 100-kilowatt A stack can do it, under ideal circumstances. But just buying a stack for 100,000 yuan is not enough. If you spend another 100,000 yuan on the BOP (battery supporting equipment), the total price will be 200,000 yuan. It is still expensive compared to the engine, but it is not completely unacceptable for an electric vehicle. Yes, the cost is still far from expected, but it is possible to complete.
"The biggest problem is lifespan. Nowadays, proton exchange membranes use a very clever structure that can be used to conduct protons, so they are expensive. Around 2000, very thick membranes were used, 170 microns , as resin is so expensive, it is certainly expensive to use such a thick film. Now that we have made it all thinner, the cost can be reduced. But the problem is that the strength of the film is very poor when it is thin, so a reinforcement layer is added, but this reinforcement layer is not enough. Strong, assuming it is 30 MPa, a 15 micron membrane, a bag can only withstand a force of 450 grams, and it will break if a bottle of mineral water is hung. "Pan Mu further said, "The other is the catalyst, in order to make the catalyst stronger. The dosage is reduced. This kind of nanomaterial has an inherent weakness, which is thermodynamic instability.
The second point is that the catalyst changes from low voltage to high voltage in every voltage cycle during the electrochemical reaction. The catalyst will change, so these will bring about problems with the life of the fuel cell. We do not have a deep understanding of its mechanism, and the solutions have not been fully realized. All these require further exploration.
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Pan Mu pointed out that when comparing the above three issues, cost ranks second and lifespan is the biggest issue, because all units and enterprises involved in the research and development of fuel cells must focus on this. It What is the mechanism? How is it caused? A large amount of test data is needed. This data is very valuable. Only with clear analysis can we make a good fuel cell vehicle.
p> In terms of fuel cell standards, Pan Mu said that only on the basis of previous work can some standards be formulated to ensure the development of fuel cells. The country now has a fuel cell standards committee, and the chairman of the committee is Academician Yi. Fuel cell vehicles are already at the forefront of the world, and standards must be formulated for many issues. Now the entire framework includes basic standards, including general technical standards for fuel cells, drive and auxiliary convenience systems, and micro.
"Internationally, our benchmark is IEC (International Electrotechnical Commission)/TC105 (Fuel Cell Technology). The current chairman is French and the previous chairman was Japanese. TC105 can build this system by cooperating with several other committees that have energy standards, transportation standards, and hydrogen supply requirements. TC105 has released fewer standards than ours. Currently, it has only released 18 standards. Our country already has 12 standards that have been adopted. "Pan Mu further explained.
How to make fuel cell vehicles? Pan Mu gave his own answer.
The development of electric vehicles should be combined with the adjustment of the energy structure It is necessary to ensure the development of fuel cell vehicles by adjusting the energy structure. What will be used to connect the power grid and the gas grid? Use fuel cells to convert hydrogen into electricity, and electrolyze water and then convert it into hydrogen. Wind power will be used to produce hydrogen and be transported throughout Europe. In the future, the hydrogen energy network will be very large. If these two networks are established, every car will be our node.
Therefore, this energy network is very consistent with the characteristics of the Internet. One is interconnected, that is, the power grid and the gas network are interconnected, and the other is unlimited nodes and two-way conversion, which can be both consumed and produced. They need to produce and sell each other. What’s interesting is that Honda’s cars are equipped with transformers to deliver electricity to households. This represents a development direction.
That’s why the International Energy Agency proposed the Energy Internet in 2015. The concept is to use hydrogen to connect the heating grid, power grid, and gas grid. Germany has proposed an integrated energy system to connect all the grid and gas grid through hydrogen. The United States has proposed the H2@Scale plan to form a network of electricity and hydrogen, in 2019. The U.S. Department of Energy also focused on supporting this matter in 2016.
The biggest obstacle facing fuel cells is the problem of life. There is a lack of mandatory standards for fuel cells, especially safety standards. Fuel cells will play an important role in the energy Internet. , electric vehicles are also part of it.
(This article is based on the shorthand of Pan Mu’s speech at the 2019 China Automobile Industry Development International Forum and has not been reviewed by me.)