Flexible piezoelectric energy harvesters using different architectures of ferrite based nanocomposites

Abstract

Electroactive phase transition in polyvinylidene fluoride (PVDF) can be economically achieved readily by addition of nanofillers. In this work, we have demonstrated the influence of rational design and structural control of nanofillers on nucleation and stabilization of an electroactive polymorph in PVDF. Different architectures of zinc ferrite (ZF) i.e. nearly spherical, nearly cubic, and rod-like were synthesized and further introduced in PVDF as a nucleating agent with different filler to polymer ratios. A comparative study of the dielectric and ferroelectric properties and energy harvesting performance of the corresponding nanocomposite was performed to obtain the best architecture based composite. It has been observed that one dimensional nanofillers are more favorable for polar phase transformation and stabilization with incorporation of a lower fraction of fillers. Thus, they exhibited maximum electrical performance (an energy storage density of 7.68 mJ cm⁻³ with an energy discharge efficiency of ∼77%, and an output piezoresponse of ∼39.10 V with a power density of 2.96 μW mm⁻³). This may be due to the preferred ‘in-plane’ orientation of the nanorod structure in the polymer matrix which helps to accumulate the entire short chain all-trans (TTTT) conformation and form an extended all-trans conformation corresponding to an electroactive β-polymorph. This study may open a new strategy to design and fabricate ferrite-PVDF based electroactive nanocomposites with desired shapes for high performance energy storage and harvesting application.