A self-supporting solid electrolyte membrane with fibrous network structure for solid state lithium metal batteries

High ionic conductivity and good interface compatibility have always been two major bottlenecks for solid-state electrolytes. Herein, a composite electrolyte membrane comprising poly (propylene carbonate), PVDF-HFP and Li_6·3La₃Zr_1·4Ta_0·6O₁₂ is successfully prepared via electrospinning. With the assistance of succinonitrile, the synthesized solid-state electrolyte exhibits high ionic conductivity (1.32 × 10⁻³ S cm⁻¹ at room temperature), oxidation potential up to 4.5 V vs Li/Li⁺ and high Li⁺ transference number (0.81). This desirable performance is attributed to the combination of PPC with good Li⁺ conduction ability and PVDF-HFP with excellent mechanical properties, forming a continuous transport framework within the electrolyte. The introduced active fillers and small molecular additive not only benefit to fast Li⁺ mobility, but also reinforce the stability towards Li metal. Li symmetric cell using the solid-state electrolyte can last for 800 h at a current density of 1.0 mA cm⁻² with a low overpotential. The NCM811 cell using the electrolyte membrane shows high initial discharge specific capacity (184.3 mAh g⁻¹ at 1 C) and good capacity retention (80.1% after 300 cycles at 30 °C).