Harnessing Flexoelectric and Piezoelectric Effects for Self-Charging Power Systems

Stretchable mechanical energy harvesters are in high demand as sustainable power sources and self-powered systems for wearable electronics and biomedical devices. In this study, a stretchable flexoelectric–piezoelectric nanogenerator (FPENG) composed of a zinc–aluminum layered double hydroxide nanosheets–ZnO nanorods (ZnAl:LDH NSs–ZnO NRs) heterostructure is developed. The coupling of the flexoelectric effect of ZnAl:LDH NSs and the piezoelectric effect of ZnO NRs enhances the output performance of the FPENG. The FPENG generates an open-circuit voltage (Voc) of 41.5 V, a short-circuit current density (Jsc) of 4.57 μA/cm2, and a maximum power density of 68.2 μW/cm2 with good mechanical durability, while the device under stretching at 60% strain generates a Voc of 1.85 V and Jsc of 0.09 μA/cm2. The energy generated from the FPENG is stored in a Li-ion battery, demonstrating a self-charging power unit. These findings present a simple method to develop FPENGs with enhanced performance by coupling flexoelectric and piezoelectric effects for wearable devices.