Processing and energy-harvesting ability of (Na,K)NbO3 particle-dispersed fibrous polyvinylidene fluoride multilayer composite

• NKN powder-dispersed flexible piezoelectric PVDF fabric was fabricated via electrospinning.
• A novel PVEH with multilayer structure was produced by laminating PVA/NKN sheets and PVDF/NKN fabrics.
• High flexibility of PVDF/NKN fabrics along longitudinal-direction is effectively utilized as for electric power generating.
• NKN powder in the PVDF fabrics played an important role in improving power generating efficiency.

Piezoelectric vibration energy harvesters are expected to be used as power sources for sensors in ubiquitous networks, and improvements in the materials and structures of harvesters are ongoing. We produced a novel vibration energy harvester with a unique material obtained by mixing lead-free piezoelectric (Na0.5K0.5)NbO3 (NKN) ceramic particles with a polyvinylidene fluoride (PVDF) fabric formed by electrospinning. The PVDF/NKN fabric showed high flexibility and was stretchable in the longitudinal-direction. Furthermore, a harvester with a multilayer structure of alternating PVDF/NKN fabrics and polyvinyl alcohol (PVA) sheets was designed and then fabricated by hot pressing. Electric power output results for the harvester suggest that the high flexibility of the fabric in the longitudinal-direction was effectively utilized and the electric power output was enhanced by incorporating NKN powder into PVDF fabric. This harvester showed a maximum power output of 145 nW/cm2 per vibration cycle at 170 Hz.