Enhancing the output power density of piezocomposite nanogenerators through rational tuning of the 3D interconnected skeleton structure

High-performance polymer-based piezoelectric nanogenerators (PENGs) are urgently needed in the field of wearable electronics to realize the self-powering of microsensors. However, the output power density of the existing classical 0-3-type PENGs is still low, which becomes a bottleneck for the application of such devices. This work achieves a large increase in the output power density of the PENGs by adopting a strategy that rationally tunes the orientation of the three-dimensional (3D) interconnected piezoceramic skeletons in the polymer matrix. In our experiments, the popular Sm-doped PMN-PT (Pb0.9625Sm0.025[(Mg1/3Nb2/3)(0.71)Ti-0.29]O-3) piezoceramic was selected as the filler, the elastic PDMS polymer was used as the matrix, and three characteristic oriented 3D skeletons were constructed based on the freeze-casting process, namely the isotropic porous (IP) structure, the uniaxial aligned lamellar (UAL) structure, and the long-range aligned lamellar (LAL) structure. It was found that the output power density of the UAL PENG is the most prominent, which is about 1.5 times that of the LAL PENG and 4 times that of the IP PENG. Theoretical analysis confirmed that the characteristic lamellar cross-linking mode in the UAL piezocomposite can significantly enhance the stress-transfer effect, resulting in a large increase of the piezoelectric potential. This work provides a promising paradigm for the design of 3D interconnected structures in piezocomposites for PENG applications.