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 [Li₂B₁₂H_{11+1/ n}] _n are in situ formed in the LiBH₄ matrix and the interface layer between [Li₂B₁₂H_{11+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.