The effect of nano-zirconia on the morphology and mechanical properties of PVDF/PAN membrane as separators in super capacitors

The PVDF/PAN/ZrO2 (zirconia) composite fibrous membranes were fabricated by electrospinning. The effects of ZrO2 content on solution properties, mechanical properties and crystallisation behaviours as well as related morphology were systematically evaluated. The scanning electron microscopy (SEM) was used to investigate the effect of ZrO2 content on the morphology of PVDF/PAN/ZrO2 composite fibrous membranes, which showed that the diameter is only 0.8 μm when the ZrO2 is 0.4%. It could be attributed to the enhancement of solution conductivity by ZrO2 addition. Nitrogen adsorption based on Brunauer-Emmett-Teller (BET) principle was employed to measure the specific surface area, which indicated that the specific surface area increased about 1.8 times for composite membranes compared to the PVDF/PAN membrane when the ZrO2 content was 0.4%. The tensile strength of fibrous membranes increased from 2.74 of pure PVDF/PAN to 5.11 MPa of PVDF/PAN/ZrO2 when the ZrO2 content was 0.4%. The differential scanning calorimetry (DSC) results showed that the crystallinity and orientation enhanced with increasing of ZrO2, which was beneficial to improve the tensile strength. The Tg and Tc shifted to high temperature with ZrO2 increases, which demonstrated that ZrO2 promoted the heterogeneous nucleation and formed perfect crystal structure.