Polymer Template Synthesis of Soft and Light Oxide Ceramics as Battery Separators

Abstract

Oxide ceramics are attractive separator materials due to their robust mechanical strength and exceptional thermal and chemical stability, but manufacturing soft oxide ceramic films is a big challenge due to the inherent brittleness of ceramics. However, we have fabricated a range of oxide ceramic nanofiber films that exhibit significant softness without fragility after various deformations by developing a sol-gel electrospinning technology followed by calcination. This approach causes the ceramic crystals to fuse together at a low temperature during their growth within the polymer nanofiber templates. All of the created oxide ceramics, from SiO₂ to BaTiO₃, Li_0.33La_0.56TiO₃ and Li₇La₃Zr₂O₁₂, have silk-like softness of <31 mN, flyweight density of <0.36 g/cm³ and robust fire-resistance to 1000 °C. Fabricated separators based on these films display high liquid electrolyte uptakes of >900% and thermal-insulation performance, enhancing the rate capability and safety of Li-batteries. The reported approach allows low-cost and scalable synthesis of oxide ceramic films that possess both soft and rigid properties.

Keywords: Electrospinning; polymer template synthesis; soft oxide ceramics; ceramic separators; high performance Li-ion batteries