Achieving high performance NASICON film based solid state lithium metal batteries with solvent free process: One stone, two birds

Oxide-based solid-state batteries (OSSB) have gained significant attention due to their inherent high safety and air stability. However, application of OSSB is limited by thick electrolytes and large interfacial resistance generated by side reactions. This work employs a solvent free process to prepare a thin Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 (LAGP) film with a thickness of 90 μm, achieving a high ionic conductivity of 0.76 mS cm −1 at room temperature. Such a high ionic conductivity originates from the filling of LAGP particles with high-conductive secondary phase, thereby forming fast interfacial conduction paths. Coupled with Li metal anode and LiFe 0.4 Mn 0.6 PO 4 (LFMP) cathode (cut-off voltage of 4.3 V), the OSSB delivers a discharge capacity of 155 mAh g −1 . Our thin-film LAGP electrolyte shows an opportunity to overcome the two obstacles, and the development of high safety OSSB becomes possible in the future.