What material is used in PEM electrolyzer bipolar plate?
Metal Bipolar Plate Applied to PEM Electrolyzer
Compared with graphite bipolar plates, metal bipolar plates have good electrical conductivity, thermal conductivity, machinability, fewer manufacturing processes, can produce ultra-thin bipolar plates, and the mass production process is mature, which can greatly reduce the amount of Production costs have attracted much attention. So far, stainless steel, aluminum alloys, titanium alloys, nickel alloys, copper alloys, and metal matrix composites have been used in bipolar plate fabrication. However, there are disadvantages of easy corrosion during use, and surface modification coating protection is required. the
Stamping and hydroforming processes
The stamping process is a method that uses a pressure device and a rigid mold to apply a certain external force to the sheet to cause plastic deformation to obtain the desired shape or size. Stamping blanks are mainly hot-rolled and cold-headed steel plates, accounting for 60% to 70% of the world's steel products. Therefore, from the perspective of raw materials, the stamping process dominates. Moreover, the stamping process produces bipolar plates with low cost and high productivity, featuring thinness (as low as 0.051 mm), uniformity, and high strength, and are widely used in automotive, aerospace, and other fields.
Rubber mat molding process
Rubber pad forming, also known as flex forming process, is a new stamping method for micro/medium runner forming, which can solve the problems of cracks, wrinkles and surface ripples during stamping and hydroforming. The rubber pad molding principle is shown in Figure 4, which consists of a rigid mold and a rubber plate, and the contact surface between them is flexible, which greatly improves the formability of micro-scale flow channels. In addition, rubber pads and rigid molds do not need to be assembled precisely during the molding process, which can greatly reduce time and cost. The main disadvantage of this molding is that the rubber pads have a short lifespan and need to be replaced frequently. the
Toyota Motor Corporation pioneered the use of metal bipolar plates and coatings on its Mirai fuel cell vehicle, solving a series of problems including corrosion, cost and conductivity. The coating materials of metal bipolar plates are shown in Table 3. It can be seen from the table that the coating materials of metal bipolar plates mainly include two types:
Type 1 is carbon-based coatings, such as graphite coatings;
The second category is metal-based coatings, such as precious metal coatings, metal carbide or nitride coatings, and metal oxide coatings.
From the perspective of the coating process route, there are currently 4 different process routes: electroplating, chemical crossing (for example: hot dipping, paint spraying, spraying), CVD (chemical vapor deposition), PVD (physical vapor deposition) . At present, the domestic application of metal plate coating is more PVD process. The coating using PVD process has high purity and good compactness, the coating is firmly bonded to the substrate, and the coating is not affected by the substrate material. It is an ideal surface modification technology for metal bipolar plates.
