Flexible PVDF/BST nanocomposites for mechanical energy harvesting application

Abstract

The development of a piezoelectric generator (PEG) that exhibits improved durability, stability, and enhanced output performance continues to be a crucial objective for self-powered and wearable electronic devices. In this study, a PEG was constructed using nanocomposite films composed of sol-gel derived Barium Strontium Titanate (BST) filler embedded within a Polyvinylidene fluoride (PVDF) matrix. This flexible polymer matrix structure is selected for its exceptional performance, flexibility, and cost-efficiency, making it ideal for advanced piezoelectric applications. Homogeneous nanocomposite films of PVDF-BST with different proportions of BST were fabricated using the solution casting method. Integrating BST filler into the PVDF matrix significantly enhances the nucleation of the electroactive β-phase, thereby improving the dielectric and ferroelectric properties, which vary according to the volume fraction of BST used. Specifically, the PVDF-BST composite containing 10 % BST (PB10) exhibited the highest electroactive β-phase content at 41.8 %, and demonstrated an energy storage density of 0.8 J/cm³ with an efficiency of 73.9 %. The dielectric constant at room temperature is seen to rise from 23 in pure PVDF to 132 in the PB20 composition at 1 kHz. The open-circuit voltage (Voc) of the PEG was recorded by exerting a periodic force on its surface. Notably, the PB10 variant achieved the highest peak-to-peak open-circuit voltage, reaching 28 V. Additionally, PB10 produced an open-circuit voltage of 22 V in response to finger tapping, highlighting its suitability for applications in touch and pressure sensing.