Hybrid piezo/triboelectric nanogenerator for highly efficient and stable rotation energy harvesting

To develop highly efficient energy harvesting means to sustainably driving miniaturized portable electronic devices, the hybrid nanogenerators (NGs) are emerging to compensate for the respective shortcomings of either type of NG. However, the crucial factors affecting the output performances of hybrid NGs still exist, such as the driving frequency, phase difference and mismatched impedance. Here, the bimorph-based piezoelectric NG was integrated into the triboelectric NG to construct a hybrid piezo/triboelectric NG (H-P/TENG) for highly efficient mechanical rotation-energy harvesting. Systematic measurements and analyses illustrated the output performance of H-P/TENG was independent of the rotation speed (driving frequency) due to the invariable periodic deformation degree of the H-P/TENG. Both NGs in the H-P/TENG had the identical phase and matched impedance in the same magnitude, which were beneficial for direct coupling of their individual rectified output signals and avoided unnecessary energy loss from the utilization of transformer. Under a low rotation speed of 100 rpm, the proposed H-P/TENG delivered high output voltage, output current and large average power/power density at similar to 210 V, 395 mu A and 10.88 mW/6.04 mW cm(-2), respectively. The output voltage/current of the sophisticated H-P/TENG could retain at similar to 210 V/400 mu A under rotation speeds from 50 to 250 rpm. Through integrating an energy managing circuit with the H-P/TENG, we developed a DC power source (stable DC output at 3.6 V) to sustainably drive RF wireless temperature sensing network and commercial electronics. The H-P/TENG was also capable of producing high output voltage (150 V) and current (150 mu A) at wind speed of 14 m/s to power 50 LEDs in parallel connection. The distinctive structure and outstanding performance of this hybrid NG is promising for the practical application of self-powered systems and the large-scale energy conversion.