A new alternative has been developed at the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT in Oberhausen Germany. Here the battery cells are sandwiched between flat bipolar plates made of conductive polymers. This makes it possible to use very thin plates, so a pack can be built which uses less than 20 percent of the material normally required to build a conventional battery pack.
The material is not subject to corrosion and can be reshaped after manufacture to support embossed structures — important for fuel cells. The bipolar plates can also be welded to make a completely sealed battery pack. In contrast, conventional bipolar plates are unsuitable for welding due to the thermal and mechanical stresses put on the structure during manufacture. Gaskets are normally required to achieve a sealed pack but these seals are bulky and prone to leaking.
A further advantage of the new material is that the researchers are able to adapt the physical properties of the bipolar plates to meet specific requirements, making the finished material either rigid or flexible and to virtually any size.
The bipolar plates are made from commercially available polymers and graphite material in a reel-to-reel process which is a particularly cost-effective production method.