Superhalogen-based lithium superionic conductors

The development of cheap, durable, and safe inorganic solid electrolytes with superionic conductivity is the key for the next generation of all-solid metal-ion batteries. The recent discovery of antiperovskites with composition Li(3)OA (A = halogen) shows promise in this regard. Here, we demonstrate the potential of a new class of antiperovskites where halogens are replaced by BH4 superhalogens. In addition to maintaining the high ionic conductivity of Li(3)OA, Li3O(BH4) is lightweight, mechanically flexible, thermodynamically more stable, and electronically more insulating than Li(3)OA. By mixing BH4 with Cl to make Li3O(BH4)(0.5)Cl-0.5, we further show that the conductivity will be doubled. The Li+-ion conductivity of the new materials is of the order of 10(-4) to over 10(-3) S cm(-1) at room temperature and will be well above 10(-2) S cm(-1) at higher temperatures below the melting point. The conduction mechanism of the material is revealed by identifying the relationship between the orientational symmetry of the BH4- rotors and the potential surface felt by the lithium ions.U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering [DE-FG02-96ER45579]; National Energy Research Scientific Computing Center by Office of Science of the U.S. Department of Energy [DE-AC02-05CH11231]; National Natural Science Foundation of China [NSFC-11274023, 21573008]; National Key Research and Development Program of China [2016YFB0100200]SCI(E)ARTICLE2613373-13381