The bipolar plate, also known as the collector plate, is one of the important components of the current fuel cell. Its main role is to provide a gas flow path, prevent hydrogen and oxygen in the battery gas chamber from colluding, and establish a current path between the Yin and Yang poles in series. The popular bipolar plate materials are mainly metal, graphite and composite materials, of which the metal bipolar plate materials are mainly stainless steel, aluminum, titanium and titanium alloys, titanium metal has a wide range of applications because of its low density, high specific strength, strong corrosion resistance and other excellent characteristics.
At present, studies have shown that compared with stainless steel and aluminum, titanium is more suitable as the substrate material of fuel cell bipolar plates from the comprehensive properties of weight, strength, resistivity and corrosion resistance after coating.
The anode potential of PEM electrolyzer is too high, and the graphite plate or stainless steel metal plate commonly used in fuel cells is easy to be corroded and degraded. The use of titanium materials can avoid ion leaching caused by metal corrosion, and prevent the activation potential of the catalyst from being interfered with. This is also the reason why the bipolar plate of China's PEM electrolyzer is basically a titanium-based bipolar plate. However, because titanium is corroded, it is easy to form a passivation layer on the surface and increase the resistance, so it is usually coated with precious metals on the titanium plate (such as platinum, iridium, gold, nickel, zirconium, etc., currently mostly platinum and gold) to protect the titanium plate.
The stamping process is more suitable for the preparation of standard parts, which is suitable for the large-scale commercial stage of PEM electrolyzer in the future. This process can significantly reduce the thickness of the substrate and reduce the manufacturing cost of the bipolar plate.