Evaluation of a new lithium complex hydride: a derivative of BH₄^- and NH^2- for fast Li-ion conduction and H₂ sorption

A new ternary complex hydride is synthesized by the interaction between Li2NH and LiBH4. The crystal structure of this new hydride is tentatively indexed using an orthorhombic cell with a space group of Pna2(1) and lattice parameters of a = 9.643 & Aring;, b = 6.228 & Aring;, and c = 5.563 & Aring;. The Li2NH-2LiBH(4) sample shows excellent hydrogenation properties with hydrogen absorption starting at near-ambient temperature (50 degrees C), which is more than 100 degrees C lower than that of pristine Li2NH. Furthermore, it attains 100% hydrogenation under isothermal conditions at 60 degrees C and 50 bar hydrogen pressure. Such superior low-temperature hydrogen absorption may be due to the formation of this new complex hydride. Interestingly, above 97 degrees C, the lithium-ion conductivity of this new hydride is higher than those of Li2NH and LiBH4 and reaches 10(-2) S cm(-1) at 114 degrees C. Meanwhile, the ionic conductivity of this new hydride is similar to 30 times higher than that of LiBH4 reaching 10(-5) S cm(-1) at room temperature. The interaction between imides and borohydrides described in this work expands the options for strategic design of novel hydrogen storage materials and solid ionic conductors.