product details
Proton exchange membrane fuel cells directly convert chemical energy from hydrogen and oxygen into electrical energy without being limited by the Carnot cycle, resulting in high energy conversion efficiency and environmental friendliness. They can be widely used in transportation and ground power generation. However, the voltage of a single battery is relatively low (0.6v~1.0v). Therefore, in order to obtain the actual available voltage, multiple single batteries need to be connected in series. The connection piece in series is called a bipolar plate, which serves to separate hydrogen and oxygen, collect current, and support membrane electrodes. At the same time, it also plays a role in the heat dissipation and drainage functions of the entire battery system. Therefore, the bipolar plate material needs to be corrosion-resistant, conductive, and Good mechanical strength and low price, easy to batch process, etc.
Bipolar plates are mainly divided into graphite bipolar plates (hard graphite bipolar plates and flexible graphite bipolar plates), composite bipolar plates, and metal bipolar plates. Among them, hard graphite is made by mechanical polishing and carving. The hard graphite bipolar plate has good corrosion resistance and conductivity, which can meet the needs of fuel cells. However, this type of bipolar plate is brittle, lacks toughness, and has high processing costs, making it unsuitable for batch preparation. However, Ballard, Canada, has developed a flexible graphite bipolar plate with high conductivity and corrosion resistance, as well as a certain degree of toughness, which can be molded and mass-produced. It is an ideal fuel cell bipolar plate. However, the strength of the raw materials for the flexible graphite bipolar plate is limited, and the thickness of the prepared bipolar plate is too thick. The thickness of the finished plate is about 2mm~3mm, resulting in a large volume of the fuel cell stack, which is not conducive to the improvement of the volume to power ratio of the battery.
Graphene has excellent optical, electrical, and mechanical properties, and has important application prospects in materials science, micro/nano processing, energy, biomedical, and drug delivery, and is considered a revolutionary material in the future; Graphene film has high conductivity and thermal conductivity; Adding a micro fold structure to the graphene film allows the material to have sufficient stretching space during stretching and bending, resulting in high flexibility. The use of graphene thin films in the preparation of fuel cell bipolar plates will significantly change the various characteristics of bipolar plates and greatly enhance their application prospects.
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