Bipolar plates contain channels through which fuel, air and water vapor flow and they need to be electrically conductive to pass the current generated by the cells. Bipolar plates can be made from conductive materials such as graphite or metal.

However, graphite plates are not economical because they need to be individually machined to create the flow channels. Metal plates suffer from surface corrosion due to the acidic environment in a fuel cell stack. ElectroPhen, a chemically inert, electrically conductive, thermoset composite material made using Bac2’s polymer technology is designed to overcome these issues.

It can be compression moulded and cured at low temperature, enabling plates to be produced quickly and economically in any quantity. Compared with other composite materials, ElectroPhen can achieve the required conductivity for fuel cell plates with a lower loading of graphite, the company says. This means that the flow properties of ElectroPhen moulding compounds are superior, leading to a better mold fill and tighter dimensional tolerance.

For prototyping purposes, Bac2 can supply either molded blank ElectroPhen plates or plates machined by Bac2 to the customers’ designs, prior to producing mould tools for high volume production. Standard blank plates are available in sizes from 60mm x 40mm up to 300mm x 200mm. The mechanical strength of ElectroPhen allows plates of 1mm thickness or less to be produced, enabling production of compact fuel cell stacks.