Pseudo-ternary LiBH 4 ·LiCl·P 2 S 5 system as structurally disordered bulk electrolyte for all-solid-state lithium batteries

International audienceThe properties of the mixed system LiBH 4-LiCl-P 2 S 5 are studied with respect to all-solid-state batteries. The studied material undergoes an amorphization upon heating above 60 1C, accompanied with increased Li + conductivity beneficial for battery electrolyte applications. The measured ionic conductivity is B10 À3 S cm À1 at room temperature with an activation energy of 0.40(2) eV after amorphization. Structural analysis and characterization of the material suggest that BH 4 groups and PS 4 may belong to the same molecular structure, where Cl ions interplay to accommodate the structural unit. Thanks to its conductivity, ductility and electrochemical stability (up to 5 V, Au vs. Li + /Li), this new electrolyte is successfully tested in battery cells operated with a cathode material (layered TiS 2 , theo. capacity 239 mA h g À1) and Li anode resulting in 93% capacity retention (10 cycles) and notable cycling stability under the current density B12 mA g À1 (0.05C-rate) at 50 1C. Further advanced characterisation by means of operando synchrotron X-ray diffraction in transmission mode contributes explicitly to a better understanding of the (de)lithiation processes of solid-state battery electrodes operated at moderate temperatures