In today's rapidly developing society and economy, what follows is not only the progress of human civilization, but also the gradual deterioration of the ecological environment and air quality on which humanity depends for survival, as well as the gradual depletion of energy resources.
Pollution and energy consumption are primarily caused by automobiles. With the continuous growth of urban transportation demand and rising income levels, automobiles have become a daily mode of transportation for urban residents in my country, leading to a continuous increase in their ownership. According to statistics from the Traffic Management Bureau of the Ministry of Public Security, as of the end of March 2017, the number of motor vehicles in China exceeded 300 million for the first time, including over 200 million cars, ranking second in the world only after the United States. There are 49 cities nationwide with more than 1 million cars, and six cities—Beijing, Chengdu, Chongqing, Shanghai, Suzhou, and Shenzhen—have more than 3 million cars.
The rapid growth in car ownership has placed enormous pressure on urban environments and traffic operations. According to the "China Motor Vehicle Environmental Management Annual Report 2017," preliminary estimates indicate that in 2016, national motor vehicle emissions totaled 44.725 million tons, including 34.193 million tons of carbon monoxide, 4.22 million tons of hydrocarbons, 5.778 million tons of nitrogen oxides, and 0.534 million tons of particulate matter. Automobiles are the primary contributor to total motor vehicle pollutant emissions, accounting for over 80% of carbon monoxide and hydrocarbon emissions, and over 90% of nitrogen oxide and particulate matter emissions. Source apportionment results for urban atmospheric particulate matter released by the Ministry of Environmental Protection show that motor vehicle emissions are the primary source in Beijing, Shanghai, Hangzhou, Guangzhou, and Shenzhen, accounting for 31.1%, 29.2%, 28.0%, 21.7%, and 41.0%, respectively. Motor vehicle emissions are the second largest source of pollution in Nanjing, Wuhan, Changsha, and Ningbo, accounting for 24.6%, 27.0%, 24.8%, and 22.0%, respectively. During periods of heavy pollution, the contribution of motor vehicle emissions is even more significant than under normal circumstances. Motor vehicle pollution has become a significant source of urban air pollution and a major cause of haze and photochemical smog.
Therefore, for humanity to survive and develop, it is imperative to stop the continued deterioration of the ecological environment and seek efficient and clean new energy sources to replace existing ones.
Fuel cells (FCs) are the fourth generation of power generation technology after thermal power, hydropower, and nuclear power. They are electrochemical power generation devices that directly convert the chemical energy stored in fuel (such as hydrogen) and oxidant (such as oxygen) into electrical energy through an electrochemical reaction process. It is the only power unit that simultaneously combines pollution-free operation, high efficiency, wide applicability, noiselessness, continuous operation, and modularity, and is considered the most promising high-efficiency and clean power generation technology of the 21st century, as shown in Figure 1.
Currently, my country has joined the strategic competition with developed countries in the field of clean energy research and development. "Fuel cell power generation technology" has been included in the "15th Five-Year Plan for Science and Technology Development and the 2015 Long-Term Plan." The Chinese Academy of Sciences launched a major project under its Science and Technology Innovation Strategic Action Plan—"High-Power Proton Exchange Membrane Fuel Cell Engine and Hydrogen Source Technology." The Chinese Academy of Sciences and the Ministry of Science and Technology have invested over 100 million RMB in this preferred clean and efficient power generation technology for the 21st century. This signifies that Chinese scientists are ready for the arrival of the hydrogen energy era at the beginning of the 21st century.
A fuel cell is a power generation device, while a dry cell battery or a rechargeable battery is an energy storage device that stores electrical energy and releases it when needed. They are two completely different types of devices. As its name suggests, a fuel cell requires continuous refueling to maintain its power output; the required fuel is hydrogen, which is why it is classified as a new energy source. The most critical technology in a hydrogen fuel cell stack, as an electrochemical reaction vessel, is the proton exchange membrane.
The proton exchange membrane (PEM) is located between the anode and cathode plates, with catalyst layers attached to both sides. Hydrogen enters from the anode of the fuel cell, while oxygen (or air) enters from the cathode. Through the action of the catalyst, the hydrogen molecules at the anode decompose into two protons and two electrons. The protons are attracted to the oxygen atoms entering from the anode, and the oxygen atoms decomposed by the catalyst are then "attracted" to the other side of the membrane. The electrons flow and transfer, forming an electric current through an external circuit, and reach the cathode. Under the action of the cathode catalyst, the protons, oxygen, and electrons react to form water molecules. Therefore, water can be considered the only emission from the fuel cell, making it a truly zero-emission, pollution-free new energy source.
The key technologies in fuel cell production lie in the encapsulation of components such as bipolar plates and proton exchange membranes. These components contain numerous micro-pores, and the miniaturization and precision of the adhesive coating process determine the sealing performance of the fuel cell stack. Good sealing performance can not only reduce the size of structural components and increase the energy density of the battery, but also extend the service life of the fuel cell.
Shichun Intelligent has conducted extensive research and development on the sealing and assembly of fuel cell stacks, and has also established key processes for bipolar plates in dispensing production. It has developed a complete set of efficient and highly reliable precision dispensing equipment. At the same time, it has developed automated equipment for upstream and downstream material sorting, feeding, bonding, locking, hot pressing, and testing, forming a complete automated production line for fuel cell packaging, as shown in Figure 2.
For adhesive application, we developed a dispensing robot that uses a high-precision actuator from HTK in Japan, a robust and rigid structural design, a servo motor from Panasonic in Japan, and a high-precision micro-dispensing valve imported from Germany. This enables automatic loading and unloading, automatic alignment, and automatic dispensing, with a dispensing accuracy of ±0.05mm.
For bonding the anode and cathode plates, we have developed a fully automated bonding robot. We have independently developed a single-axis motion robot, a grinding-grade lead screw, and a servo motor from Panasonic, Japan, as well as a conveyor belt with multiple transmission links. The bonding accuracy of the anode and cathode plates can reach ±0.05mm.
For the curing of the adhesive, we initially used a vertical baking oven with a temperature control accuracy of 3%. After the adhesive has cured, the accuracy of the adhesive strip can reach ±0.05mm.
Because fuel cell encapsulation requires high precision in the adhesive strips and stringent sealing performance, we have developed an online adhesive shape inspection robot and a sealing performance inspection robot. The adhesive shape inspection robot can identify adhesive shapes with an accuracy of up to ±0.005mm, while the sealing performance inspection robot achieves an accuracy of ±0.5%. The screening robot automatically identifies and separates the adhesive strips that pass the inspection.
The development, research, and commercialization of fuel cells are crucial for achieving energy conservation and environmental protection. The advanced nature and practicality of fuel cells are widely recognized. While some challenges remain in increasing investment in their development, research, and utilization, such as issues with electrode materials, manufacturing costs, and catalysts, these shortcomings do not overshadow their potential. Accelerating fuel cell development is an inevitable global trend. In the process of developing fuel cells, targeted research should be conducted based on the individual advantages, disadvantages, and developmental obstacles of different fuel cell types to ensure that all types of fuel cells can fulfill their intended functions.
