In Situ Formed Li–B–H Complex with High Li-Ion Conductivity as a Potential Solid Electrolyte for Li Batteries

Li–B–H complexes facilely prepared via partial dehydrogenation of LiBH4 are presented in this study as solid electrolytes for Li batteries. An exceptionally high Li-ion conductivity is found for the Li–B–H complex with 7.5 wt % H2 desorption under 3 bar H2 pressure, which reaches 2.7 × 10–4 S cm–1 at 35 °C, more than 4 orders higher than that of LiBH4. In-depth characterizations show that LiH and [Li2B12H11+1/n]n are in situ formed in the LiBH4 matrix and the interface layer between [Li2B12H11+1/n]n and LiBH4 is believed to be responsible for the high Li-ion conductivity. Moreover, this Li–B–H complex also exhibits excellent electrochemical stability, which enables the stable cycling of all-solid-state batteries at room temperature.