Effect of β-Chain Alignment Degree on the Performance of Piezoelectric Nanogenerator Based on Poly(Vinylidene Fluoride) Nanofiber

This work demonstrated the effect of the beta-chain alignment degree on piezoelectric nanogenerator (PNG) performance. A simple, safe and low-cost fast-centrifugal spinning technique was used to produce self-poled poly(vinylidene fluoride) (PVDF) nanofiber. PNG based on acetone-prepared PVDF fibers, with high beta-chain alignment, generated output open-circuit voltage (V-OC) and short-circuit current (I-SC) five times higher than the film counterpart In addition, the fibers showed a remarkable increase in beta-chain alignment degree as the ratio of N,N-dimethylformamide (DMF) solvent increased. The optimum nanofiber with the highest beta-chain alignment degree, beta-fraction and piezoelectric charge coefficient of 0.93, 91.8% and -120 pC.N-1 was obtained, respectively. PNG based on the optimum fiber displayed the highest V-OC, I-SC and power density of 14 V, 1.4 mu A and 6.7 mu Wcm(-2), respectively. This performance is greater than any PNG made from electrospun PVDF fiber. The excellent performance of the fabricated PNGs was strongly related to the high alignment degree of beta-chains parallel along the fiber axis. In addition, due to low Young's modulus (1.63 MPa) of the optimum fibers, the related lead-free PNG is sensitive to small movements and can be used in wearable and implanted medical devices.