PVDF-Nanofibers/PET-Nonwoven Sandwich Coated with Fine γ-AlO(OH): A Bilayer Hybrid Composite Separator for Lithium-Ion Batteries

Abstract

Nanofiber-based separators fabricated via electrospinning for lithium-ion batteries have garnered widespread attention due to their attractive porous characteristics, improved thermal stability, and high electrolyte wettability. A double-layer PVDF/PET/γ-AlO(OH) hybrid composite membrane is prepared by combining simple electrospinning techniques with drop casting onto thermally pressed PET/PVDF surfaces, resulting in a finely dispersed and uniform boehmite (γ-AlO(OH)) coating. The 3D interconnected structure of the PVDF/PET/γ-AlO(OH) hybrid composite membrane exhibits excellent mechanical properties and demonstrates outstanding electrolyte absorption, with supervisor electrolyte uptake of 582.5% and remarkable ionic conductivity of 1.2 × 10⁻² S cm⁻¹. Even after heating at 130 °C for 1 h, the membrane maintains good thermal stability. Li₄Ti₅O₁₂/LiNiMnCoO₂ batteries employing the double-layer PVDF/PET/γ-AlO(OH) hybrid composite membrane exhibit exceptional discharge capacity (105.7 mAh g⁻¹ at 0.2 C) and outstanding capacity retention (100%). The battery performance results clearly demonstrate the suitability of the double-layer PVDF/PET/γ-AlO(OH) hybrid composite membrane as a safe separator for lithium-ion batteries.