Flexible piezoelectric energy harvester with an ultrahigh transduction coefficient by the 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.