Researchers at a German research institute have completely redeveloped the stack in a redox flow battery in a bid to reduce material usage and costs.
Scientists at the Fraunhofer Institute for Environmental, Safety and Energy Technology (Fraunhofer UMSICHT) developed a way to manufacture the central, electrically conductive plastic so it remains flexible and can be welded.
The team of researchers used similar base materials — graphite and carbon black — to conventional redox flow batteries but used plastic ground into powder and mixed with 80% graphite by weight.
They then sent the powder through a system comprising rollers heated to different temperatures and moving at different speeds.
The powder was briefly melted between the rollers at moderate temperatures and low pressures before being rolled into a sheet and finally rolled up.
This gave the material thermoplastic properties, so it was flexible and could be welded.
Professor Christian Doetsch from Fraunhofer UMSICHT, said: “The stack that has been developed, the heart of any redox flow battery, is 40% more cost-effective in terms of material costs.
“Production costs have also been significantly reduced. The stack weighs 80% less than a conventional stack and is only about half the size.”
The stack is being marketed by the Volterion, a spin-off of the Fraunhofer UMSICHT.
Bipolar plates up to several square meters in size can be manufactured without problems using the new method, with plate thickness between 0.1 and 0.4 millimeters.