Methylamine Lithium Borohydride as Electrolyte for All‐Solid‐State Batteries
Jakob B. Grinderslev, Lasse N. Skov, Jacob G. Andreasen, Shaiq Ghorwal, Jørgen Skibsted, Torben R. Jensen
Abstract
Abstract Fast Li‐ion conductivity at room temperature is a major challenge for utilization of all‐solid‐state Li batteries. Metal borohydrides with neutral ligands are a new emerging class of solid‐state ionic conductors, and here we report the discovery of a new mono‐methylamine lithium borohydride with very fast Li + conductivity at room temperature. LiBH 4 ⋅CH 3 NH 2 crystallizes in the monoclinic space group P 2 1 / c , forming a two‐dimensional unique layered structure. The layers are separated by hydrophobic −CH 3 moieties, and contain large voids, allowing for fast Li‐ionic conduction in the interlayers, σ (Li + )=1.24×10 −3 S cm −1 at room temperature. The electronic conductivity is negligible, and the electrochemical stability is ≈2.1 V vs Li. The first all‐solid‐state battery using a lithium borohydride with a neutral ligand as the electrolyte, Li‐metal as the anode and TiS 2 as the cathode is demonstrated.