Researchers at Empa have reached a milestone in the search for a solid electrolyte, the conductive medium for future solid-state batteries. On the one hand, this material must be highly conductive for lithium ions, and on the other, it must be as cheap as possible to produce industrially. Ultra-thin layers of a special ceramic (LLZO, chemically Li7La3Zr2O12) should make the production of high-performance solid-state batteries possible in the near future.
Lithium-ion batteries can pose a risk due to the highly flammable liquid inside them. However, this electrolyte liquid could be replaced by a non-flammable and heat-resistant solid in the future. In addition to improved safety, the higher performance and longer service life of such batteries would also be significant advantages. The research team is focusing on thin-film technologies for the development of these new solid-state batteries. Using magnetron sputtering, they succeeded in producing the LLZO ceramic in the form of an ultra-thin film of around 500 nanometers. Measurements revealed a significantly higher conductivity compared to previously known materials.
Solid-state microbatteries based on lithium phosphorus oxynitride (LiPON) are already available today. However, the conductivity of the LLZO thin film developed at Empa exceeds their conductivity more than a hundredfold. In a next step, the researchers were able to test the material in a laboratory version of a thin-film battery. And indeed, the new LLZO thin film also showed a significantly higher conductivity in this test battery than the previously known LiPON batteries.
LLZO solid-state batteries are particularly interesting for smaller devices with high power requirements, for example in consumer electronics or IoT devices. The thin-film design of solid-state batteries promises shorter charging times and a longer service life than today's liquid-filled lithium-ion batteries.
