Rational design of PVDF/BaTiO₃ nanoparticle/Cu nanowire ternary nanocomposite films for optimal piezoelectric power generation

Flexible polymers, ferroelectric ceramic nanoparticles, and conductive nanomaterials have been intensively studied with the aim of exploiting their unique properties synergistically and producing a ternary composite displaying excellent piezoelectric performance. Therefore, it is important to understand the role of conductive nanomaterials in ternary nanocomposites for piezoelectric power generation. In this study, the effect of Cu nanowire (CuNW) addition on the dielectric, ferroelectric, and piezoelectric properties of poly(vinylidene fluoride) (PVDF)/BaTiO₃ nanoparticle (BTNP)/CuNW composite films was systematically investigated. The experimental results reveal that ternary composites with 0.04 vol. % CuNWs generated the highest total charge and power density among samples of varying CuNW content. When 0.04 vol. % CuNWs were incorporated into the PVDF/BTNP binary composite, the remanent polarization $(Pr)$ increased from $0.51$ to $1.63μC/cm2$ due to an enhanced effective electric field. However, when the CuNW content exceeded 0.04 vol. %, $Pr$ started to decrease owing to an increase in the leakage current and the enhancement in the pinning effect of the PVDF dipoles. When an excessive amount of CuNWs was added to the composite, the piezoelectric performance showed only a moderate decrease owing to the enhanced stress transfer. Conductive nanowires are often incorporated into piezoelectric ternary composites to facilitate the dispersion of piezoelectric nanoparticles and for stress transfer. However, composites with a more than 0.04 vol. % CuNWs have a lower net polarization and piezoelectric power density. When the CuNW content is optimized (0.04 vol. %), the maximum power density of the ternary composite film can be enhanced by up to 520%.