Ultrathin, dense, hybrid polymer/ceramic gel electrolyte for high energy lithium metal batteries

To realize energy densities in comparison to organic-liquid-electrolyte-level batteries, ultrathin gel polymer electrolytes (GPEs) with wide potential window and good mechanical properties are desired. However, GPEs with comparable thicknesses to commercial polymer separators (<10 μm) remain challenging to synthesize because their porous configurations reduce the mechanical properties and increase the risk of short circuiting. Here, we report an ultrathin 7.3-μm-thick polymer/ceramic electrolyte membrane fabricated by hybridizing poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) with garnet LiMgLaZrTaO (LLZTO), demonstrated with a dense configuration. In comparison with the porous PVDF-HFP membrane, the hybrid PVDF-HFP/LLZTO membrane not only exhibits robust mechanical strength (23.94 MPa versus 1.43 MPa), high Young's modulus (557.95 MPa versus 13.43 MPa), wide potential window (6.0 V versus 5.5 V), but also prevents lithium dendrites (0.5 mA cm versus < 0.1 mA cm).