Flexible Piezoelectric Energy Harvester with Ultrahigh Transduction Coefficient by Interconnected Skeleton Design Strategy

Based on the strong demand for self-powered wearable electronic devices, flexible piezoelectric energy harvesters (FPEHs) have recently attracted much attention. A polymer-based piezocomposite is the core of an FPEH and its transduction coefficient (d33 × g33) is directly related to the material's power generation capacity. Unfortunately, the traditional 0–3 type design method generally causes a weak stress transfer and poor dispersion of the filler in the polymer matrix, making it difficult to obtain a high d33 × g33. In this work, a unique interconnected skeleton design strategy has been proposed to overcome these shortcomings. By using the freeze-casting method, an ice-templated 2–2 type composite material has been constructed with the popular piezoelectric relaxor 0.2Pb(Zn1/3Nb2/3)O3–0.8Pb(Zr1/2Ti1/2)O3 (PZN–PZT) as the filler and PDMS as the polymer matrix. Both the theoretical simulation and the experimental results revealed a remarkable enhancement in the stress transfer ability and piezoelectric response. In particular, the 2–2 type piezocomposite has an ultrahigh transduction coefficient of 58 213 × 10−15 m2 N−1, which is significantly better than those of previously reported composite materials, and even textured piezoceramics. This work provides a promising paradigm for the development of high-performance FPEH materials.