Fabrication of triboelectric polymer films via repeated rheological forging for ultrahigh surface charge density

High charge density is the foundation to promote a wide range of applications of triboelectric nanogenerators. Here, authors propose a processing method based on the repeated rheological forging of triboelectric polymers achieving an enhanced triboelectricity and further study its mechanism. Triboelectric polymer with high charge density is the foundation to promote the wide range of applications of triboelectric nanogenerators. This work develops a method to produce triboelectric polymer based on repeated rheological forging. The fluorinated ethylene propylene film fabricated by repeated forging method not only has excellent mechanical properties and good transmittance, but also can maintain an ultrahigh tribo-charge density. Based on the film with a thickness of 30 mu m, the output charge density from contact-separation nanogenerator reaches 352 mu C center dot m(-2). Then, the same film is applied for the nanogenerator with air-breakdown mode and a charge density of 510 mu C center dot m(-2) is further achieved. The repeated forging method can effectively regulate the composition of surface functional groups, the crystallinity, and the dielectric constants of the fluorinated ethylene propylene, leading to the superior capability of triboelectrification. Finally, we summarize the key parameters for elevating the electrification performance on the basis of molecular structure and related fabrication crafts, which can guide the further development of triboelectric polymers.