Robust and Flexible Piezoelectric Lead-Free Zn-BCZT/PVDF-HFP Nanogenerators for Wearable Energy Harvesting

Herein, flexible piezoelectric nanogenerators were fabricated based on polymer composites containing synthesized lead-free piezoceramics Ba 0.85 Ca 0.15 Zr 0.10 Ti 0.90 O 3 (BCZT) and zinc-doped BCZT (Zn-BCZT). Polyvinylidene fluoride- co -hexafluoropropylene (PVDF-HFP)-based composites were prepared through the solution casting method. The morphology and microstructure were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The distributions of crystallinity and β-phase fractions were also studied. Impedance measurements illustrate the accumulation of space charge in the high-frequency range and the existence of a non-Debye relaxation. The results show that a 10 wt % Zn-BCZT/PVDF-HFP nanogenerator can generate a maximum peak-to-peak output voltage of 3.3 V and a power of 2.13 μW for a load resistance of 1 MΩ under mechanical shaking. This nanogenerator can successfully harvest a good output voltage of up to 8 V under daily life movements such as walking. This study demonstrates the importance of doping zinc within BCZT to boost the piezoelectric performance as it contributes to minimize the crystallite particle size and enhance the crystal β-phase transformation of the polymer matrix. Hence, the 10 wt % Zn-BCZT/PVDF-HFP nanogenerator has great potential for use in wearable technologies. Furthermore, the nanogenerator demonstrates good stability over 1800 cycles of repetitive load and good reliability even after 1 year. These results indicate the robustness of the developed nanogenerator in practical applications.