Unparalleled lithium and sodium superionic conduction in solid electrolytes with large monovalent cage-like anions

摘要: Solid electrolytes with sufficiently high conductivities and stabilities are the elusive answer to inherent shortcomings of organic liquid prevalent in today's rechargeable batteries. We recently revealed a novel fast-ion-conducting sodium salt, Na2B12H12, which contains large, icosahedral, divalent B12H122− anions that enable impressive superionic conductivity, albeit only above its 529 K phase transition. Its lithium congener, Li2B12H12, possesses an even more technologically prohibitive transition temperature 600 K. Here we show chemically related LiCB11H12 NaCB11H12 salts, contain monovalent CB11H12− anions, both exhibit much lower temperatures near 400 380 K, respectively, truly stellar ionic (>0.1 S cm−1) unmatched by any other known polycrystalline materials at these temperatures. With proper modifications, confident room-temperature-stabilized salts incorporating such large polyhedral anion building blocks attainable, thus enhancing their future prospects as practical electrolyte next-generation, all-solid-state