Flexible piezoelectric materials are pivotal to a variety of emerging applications ranging from wearable electronic devices, sensors to biomedical devices. Current ceramic-polymer composites with embedded low-dimensional ceramic fillers, though mechanically flexible, suffer from low piezoelectricity owing to the poor load-transfer efficiency that typically scales with the stiffness ratio of the polymer matrix to the ceramic fillers. Herein we introduce the scalable ceramic-polymer composites based on three-dimensional (3-D) interconnected piezoelectric microfoams. Comprehensive mechanics analyses reveal that the 3-D interconnected architecture presents a continuous pathway for load transfer to break the load-transfer scaling law seen in the conventional composites with low-dimensional ceramic fillers. The 3-D composite exhibits exceptional piezoelectric characteristics under multiple loading conditions (i.e., compression, stretching, and bending) and high mechanical durability under thousands of cycles. The 3-D composite also displays excellent pyroelectricity, thereby enabling concurrent thermal and mechanical energy scavenging. Our findings suggest an innovative material framework for high-performance energy harvesters and self-powered micromechanical devices.

We report the sea sponge-inspired design and preparation of piezoelectric composite generators (PCGs) based on a three-dimensional electroceramic skeleton. The remarkable improvements in the piezopotential of the bioinspired structure have been theoretically analyzed using numerical simulations based on a phase-field simulation. The open-circuit voltage, short-circuit current density and instantaneous power density of the bioinspired PCG reach up to ∼25 V, ∼550 nA cm⁻² and ∼2.6 μW cm⁻², respectively, corresponding to about 16 times higher power than that of conventional particle based piezoelectric polymer composites. Moreover, the bioinspired PCG displays 30 times higher strain–voltage efficiency under stretching than the state-of-the-art performance of the flexible piezoelectric energy harvesters reported so far.