Thin and Flexible Solid State Electrolytes for Ambient and Middle Temperature Storage Systems

Solid state electrolytes are generally used in high-temperature systems such as fuel cells or sodium/sulfur batteries. They are mostly found in stationary energy storage applications. On the one hand solid state electrolytes have a high ionic conductivity especially at elevated temperatures. On the other hand, they are very brittle and fragile because they are made of ceramic or glass-like materials. To use the solid state electrolyte in next generation systems, such as in Li/S, Li/Air or sodium-based systems at ambient or middle temperature, the solid state electrolyte is embedded in a flexible, ductile and non-metallic material by using a recently developed manufacturing process. The advantage of those materials is the possibility of their plastic deformation under stress.

By using adjusted and optimized electrolytes for each electrode in the Li/S battery, intrinsic parasitic effects like the polysulfide shuttle mechanism or electrolyte degradation at the side of the alkaline metal anode could be prevented. As an alternative to lithium today sodium-based systems have become an interesting subject for researchers. Due to the low melting temperature of sodium (about 100 °C), it is conceivable to use molten sodium as an anode separated with a thin, flexible and stable solid state electrolyte from a cathode. With this design a formation of dendrites and a reaction with a liquid electrolyte should be avoided and improved cycling stability can be obtained.