Flexible composite graphite bipolar plates production line

The bipolar plate, also known as the collector plate, is one of the important components of the fuel cell. It has the following functions and properties: separates the fuel from the oxidiser and prevents the gas from passing through; collects and conducts current with a high conductivity; is designed and machined with flow channels that distribute the gas evenly to the reaction layer of the electrodes for electrode reactions; can discharge heat and maintain a uniform cell temperature field; is corrosion resistant; is resistant to shock and vibration; is thin; is light in weight; and is also low cost, easily machined and suitable for batch manufacture etc.

The function of the bipolar plate (also known as the bulkhead) is to provide a gas flow path to prevent the hydrogen in the gas chamber of the battery from passing in series with the oxygen and to establish a current path between the cathode and anode in series. The thickness of the bipolar plate should be as thin as possible to reduce the resistance to current and heat conduction, while maintaining a certain mechanical strength and good gas barrier effect.

Bipolar plate materials can be broadly divided into three categories: carbon materials, metal materials and metal and carbon composites.

(1) Carbon materials. Carbon materials include graphite, moulded carbon materials and expanded (flexible) graphite. Conventional bipolar plates are made of dense graphite and mechanically processed into gas flow channels. -Graphite bipolar plates are chemically stable and have low contact resistance with the MEA.

(2) Metal materials. Metal materials such as aluminium, nickel, titanium and stainless steel can be used to make bipolar plates. Metal bipolar plates are easy to process, can be manufactured in bulk, low cost, thin thickness, high volume specific power and specific energy of the battery.

(3) Composite materials. If the contact resistance between the bipolar plate and the MEA is large, the ohmic resistance produces more polarization loss and the operating efficiency decreases. Among the various bipolar plate materials in common use, graphite materials have the smallest contact resistance, stainless steel and titanium are formed on the surface of the non-conductive oxide film to increase the contact resistance.