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

Herein, flexible piezoelectric nanogenerators were fabricatedbasedon polymer composites containing synthesized lead-free piezoceramicsBa(0.85)Ca(0.15)Zr(0.10)Ti(0.90)O(3) (BCZT) and zinc-doped BCZT (Zn-BCZT). Polyvinylidenefluoride-co-hexafluoropropylene (PVDF-HFP)-basedcomposites were prepared through the solution casting method. Themorphology and microstructure were investigated using Fourier transforminfrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanningelectron microscopy (SEM). The distributions of crystallinity and & beta;-phase fractions were also studied. Impedance measurementsillustrate the accumulation of space charge in the high-frequencyrange and the existence of a non-Debye relaxation. The results showthat a 10 wt % Zn-BCZT/PVDF-HFP nanogenerator can generate a maximumpeak-to-peak output voltage of 3.3 V and a power of 2.13 & mu;Wfor a load resistance of 1 M & omega; under mechanical shaking. Thisnanogenerator can successfully harvest a good output voltage of upto 8 V under daily life movements such as walking. This study demonstratesthe importance of doping zinc within BCZT to boost the piezoelectricperformance as it contributes to minimize the crystallite particlesize and enhance the crystal & beta;-phase transformation of the polymermatrix. Hence, the 10 wt % Zn-BCZT/PVDF-HFP nanogenerator has greatpotential for use in wearable technologies. Furthermore, the nanogeneratordemonstrates good stability over 1800 cycles of repetitive load andgood reliability even after 1 year. These results indicate the robustnessof the developed nanogenerator in practical applications.