Polyvinylidene fluoride injection electrets: preparation, characterization, and application in triboelectric nanogenerators

Abstract The electrical output performances of polyvinylidene fluoride (PVDF) triboelectric nanogenerators (TENGs) were closely related to its surface potential, surface roughness, β crystalline form, crystallinity, and dielectric constant. In order to improve the high power output, high voltage thermal polarization with injection molding (HVTP-IM) was integrated as a single-process to achieve the injection of PVDF electrets. The physical properties of these injection electrets were explored, including surface potential, surface morphology, crystalline transition, crystallinity, and dielectric constant by changing HVTP-IM temperatures, voltages, and times. The optimal polarization condition during the HVTP-IM process was set at 90 °C, 40 MV/m, and 30 min by comprehensive analysis, and the peak intensity of β-crystal under this condition was 2.03 times as much as that of the virgin PVDF without HVTP-IM. Vertical contact-separated TENGs were constructed via PVDF injection electrets, and their performances were studied by measuring the output electrical signals. The output current and voltage of TENGs based on PVDF injection electrets were twice and seven times higher than that of without treatment by HVTP-IM, and the maximum could be reached 75 µA and 15 V. This study paves a new path for improving the properties of PVDF or other materials to enhance the output performances of triboelectric nanogenerators when they are used as triboelectric materials.