The new material is based on the sodium-phosphorus-sulphur family of solid electrolytes, similar to materials being developed for solid state lithium ion batteries. Adding 19% tin into the formula boosted ionic conductivity to a high of 0.67 mS cm-1. The crystal structure of the conductor had a high number of channels and pathways for sodium ions to pass through. The team went on to test a prototype battery, itself using a sodium-tin alloy electrode, to demonstrate its potential application.
Sodium ion batteries are cheaper than lithium ion technologies, though with lower charge capacity, and solid state versions are safer because they don’t have flammable components. They are most likely to be used in larger scale energy storage applications.