Battery and electric insulator

People in charge : Odile Fichet

Some of the materials developed at the LPPI have been designed to solve certain issues concerning energy storage and conversion. That’s why, functional materials, ionic conductors, were evaluated as fuel cell membranes or for metal-air batteries and structural materials, made with polimides and/or polysiloxanes, as electrical insulation materials. Tests allow to assess their interest compared to existing materials, but also their limitations. The synthesis is then reviewed and optimized.

Based on Nafion ®’s morphology, reference membrane for fuel cells, new RIPs were developed combining a network of fluorinated polymers to a protonic conductive polyelectrolytic network. The fluorinated polymer network restricts membrane’s deformation during operation and ensures its mechanical holding, while, at the same time, the polyanion network allows protonic conduction through the membrane. These materials have a swelling rate in water of 22-59% by mass and a protonic conduction of 1-63ms/cm. What’s more, they are 10 times less permeable to oxygen and hydrogen than Nafion®. However, RIPs performance as a fuel cell membrane is still slightly lower then Nafion®.

In the same way, RIPs that combine a polycation with a neutral polymer protect air electrodes from carbonatation when positioned between the electrode and the electrolyte In an air-metal battery. While the unprotected air electrode only works 60 hours in LiOH 5M in cycling when fed by untreated air, the same electrode modified by a fluorinated polymer RIP/ PECH remains stable more than 1550 h in operation in the presence of LIOH 5M and more than 6000 h in the presence of concentrated potash.