Swift heavy ions irradiated PVDF/BaTiO3 film as a separator for supercapacitors
Abstract Swift heavy ion (SHI) irradiated PVDF and (0.8)PVDF/(0.2)BaTiO3 films (thickness ~ 0.06 μm) have been studied as a separator for supercapacitors. Samples were irradiated by O6+ and Li3+ ions at fluence 2 × 1011 and 2 × 1012 ions/cm2, respectively. The irradiation-induced α → β phase transition in the PVDF polymer matrix, whereas complete amorphization in BaTiO3 filler is observed in nanocomposite films. The estimated value of percentage porosity (P%) for the irradiated composite films is comparable to the P% values for commercially available Cellulose separators. The flexibility is retained even after irradiation owing to irradiation-induced cross-linking in the PVDF matrix. The Cyclic Voltammetry (CV) curves retain their shape without distortion with increasing scan rate (20–180 mA s−1) showing the high rate performance of the separators. The electrochemical impedance spectra of Ni/separator/Ni blocking cells after the 1st and 200th cycles are analyzed to evaluate the bulk electrolyte resistance (Rbe) and conductivity under the cyclable performance of the separator films. The Rbe for the 1st cycle for irradiated PVDF and (0.8)PVDF/(0.2)BaTiO3 separator films are ranged from 0.4–1.4 Ω, which is much lower than Rbe for commercially available non-porous Celgard™ 2500 (88.2 Ω) and micro-porous Celgard Ez 2090 (47.1 Ω) separators. However, the conductivity values are higher than that of commercially available Cellulose and Celgard™ 2500 separators.