Ultra-thin free-standing sulfide solid electrolyte film for cell-level high energy density all-solid-state lithium batteries

All-solid-state lithium batteries with high safety and high energy density are one of the most promising next generation energy storage devices. However, the enhancement of energy density of all-solid-state lithium batteries is generally hindered by the thick and heavy solid electrolyte layer. In this work, a 5 nm thick homogeneous polydopamine layer is coated on the Li6PS5Cl electrolyte particles in organic alkali solution, resulting in a modified adhesive particle surface. Free-standing polydopamine-coated Li6PS5Cl thin film with thickness of 35 μm could be achieved by cold pressing. All-solid-state lithium battery with the polydopamine-coated Li6PS5Cl thin film is assembled and exhibits a discharge capacity of 485.1 mAh g−1 after 100 cycles with a capacity retention of 78.5% at 0.1 C and 25 °C. A high full-cell level energy density of 284.4 Wh kg−1 can be realized with reduced thickness and weight of electrolyte layer.