A cost-effective, ionically conductive and compressible oxychloride solid-state electrolyte for stable all-solid-state lithium-based batteries

To enable the development of all-solid-state batteries, an inorganic solid-state electrolyte should demonstrate high ionic conductivity (i.e., > 1 mS cm⁻¹ at 25 °C), compressibility (e.g., > 90% density under 250-350 MPa), and cost-effectiveness (e.g., < $50/kg). Here we report the development and preparation of Li1.75ZrCl4.75O0.5 oxychloride solid-state electrolyte that demonstrates an ionic conductivity of 2.42 mS cm⁻¹ at 25 °C, a compressibility enabling 94.2% density under 300 MPa and an estimated raw materials cost of $11.60/kg. As proof of concept, the Li1.75ZrCl4.75O0.5 is tested in combination with a LiNi0.8Mn0.1Co0.1O₂-based positive electrode and a Li₆PS₅Cl-coated Li-In negative electrode in lab-scale cell configuration. This all-solid-state cell delivers a discharge capacity retention of 70.34% (final discharge capacity of 70.2 mAh g⁻¹) after 2082 cycles at 1 A g⁻¹, 25 °C and 1.5 tons of stacking pressure.