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

Abstract

Solid state electrolytes are generally used in high-temperature systems such as fuel cells or sodium/sulfur batteries. They are common in stationary energy storage applications. The benefit of the solid state electrolytes is their high ion selective conductivity, even exceeding the value of most liquid electrolytes at elevated temperatures. But a widespread use is hindered by their brittleness and fragility. 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 composite materials is the possibility of their plastic deformation under stress. The connection between the solid state electrolyte and the ductile material can be established for example by surface bonding.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 commercialized lithium-based batteries sodium-based systems become more and more popular. 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 the liquid electrolyte could be reduced and improved cycling stability can be obtained.