Li3TiCl6 as ionic conductive and compressible positive electrode active material for all-solid-state lithium-based batteries

Abstract

The development of energy-dense all-solid-state Li-based batteries requires positive electrode active materials that are ionic conductive and compressible at room temperature. Indeed, these material properties could contribute to a sensible reduction of the amount of the solid-state electrolyte in the composite electrode, thus, enabling higher mass loading of active materials. Here, we propose the synthesis and use of lithium titanium chloride (Li3TiCl6) as room-temperature ionic conductive (i.e., 1.04 mS cm−1 at 25 °C) and compressible active materials for all-solid-state Li-based batteries. When a composite positive electrode comprising 95 wt.% of Li3TiCl6 is tested in combination with a Li-In alloy negative electrode and Li6PS5Cl/Li2ZrCl6 solid-state electrolytes, an initial discharge capacity of about 90 mAh g−1 and an average cell discharge voltage of about 2.53 V are obtained. Furthermore, a capacity retention of more than 62% is attainable after 2500 cycles at 92.5 mA g−1 and 25 °C with an applied external pressure of 1.5 tons. We also report the assembly and testing of a “single Li3TiCl6” cell where this chloride material is used as the solid electrolyte, negative electrode and positive electrode.