Research And Preparation Of Dielectric Composites For Triboelectric Nanogenerators

Triboelectric nanogenerators can convert distributed mechanical energy in the environment into electrical energy to realize self-powered systems.However,the low output of triboelectric nanogenerators seriously affects its role in the new energy era.Therefore,designing materials and structures with ultra-high surface charge densities to improve the output power of triboelectric nanogenerators is a key factor in advancing the commercial application of triboelectric nanogenerators.In this paper,the influence of the dielectric constant of the friction layer material of the triboelectric nanogenerator on its output performance was explored.The output surface charge density of the triboelectric nanogenerator was improved by the voltage-multiplying circuit.Then the roll-to-roll process was designed to improve the output performance of the friction layer.We break through the bottleneck of production capacity while maintaining high output performance.The main work of this paper is as follows:（1）In this work,we increase the dielectric constant of the friction layer.Utilizing the poly（tert-butyl acrylate）（PtBA）shell in situ growth method,not only the surface energy of Ba TiO₃ nanoparticles is reduced and their dispersibility is improved,but also a net dipole moment is provided by the ester group of PtBA.The Ba TiO₃-PtBA/PVDF nanocomposite films formed by filling core-shell nanoparticles into a polyvinylidene fluoride（PVDF）matrix have a dielectric constant as high as 15.Furthermore,due to the excellent mechanical properties of the PtBA shell,the nanocomposite membrane still exhibits good flexibility and integrated surface micromorphology at a high loading rate of 30%.The current density of the triboelectric nanogenerator prepared with Ba TiO₃-PtBA/PVDF nanocomposite is 2.1μA/cm²,which is 2.5 times than that of the unmodified triboelectric nanogenerator.By adjusting the surface charge density by ion implantation,the current density can be further increased to 6.1μA/cm².The results show that the high dielectric constant nanocomposite films prepared by in situ atomic radical polymerization（ATRP）technology can effectively improve the output performance of triboelectric nanogenerators.（2）The using of voltage-multiplying circuit to effectively break through the bottleneck of insufficient electrification of high dielectric constant materials.While this method is also affected by the dielectric constant,thickness of the film and the leakage current of the friction layer material itself.The output performance of the triboelectric nanogenerator with Ba TiO₃-filled PVDF composite film as the friction layer is enhanced by using a voltage-multiplying circuit.At the same time,by adding another layer of polystyrene（PS）under the composite film as a shielding layer,the leakage current is effectively reduced.Due to the reduction of leakage current,the output charge density of the composite film is further improved,thus better performance can be obtained.Moreover,taking the advantages of the introduction of the charge storage layer,the friction layer itself will be less affected by the defects caused by doping.Thus,the performance can be further improved by reducing the thickness of the high dielectric constant composite film under high doping conditions.This approach can be applied to different ferroelectric materials to increase their dielectric constants while enhancing the output performance,which provides new guidance for the optimization of dielectric materials.（3）Based on the aforementioned research,by introducing the fluorine-containing silane to enhance electronegativity,the fluorine MAPDMS（MAPDMS-F）can achieve a high surface charge density,whose charge density is nearly doubled compared with that of untreated MAPDMS.The ultrafast continuous fabrication of triboelectric nanogenerators was successfully achieved through an ultrafast ultraviolet photopolymerization strategy.This method makes it possible to manufacture large-scale and efficient industrial triboelectric nanogenerators and solving the bottleneck of practical application of triboelectric nanogenerators.The charge density of the triboelectric nanogenerator in contact separation mode is close to the maximum limit of the normal environment.In addition,the MAPDMS-F film has good light transmittance（95%）and good water resistance,and can be used in newly designed greenhouses to power sensor networks.It can not only collect thermal energy for greenhouse insulation,but also collect raindrop energy in rainy days.This energy also enables self-powered sensor network to monitor the condition of the greenhouse in real time.In this study,the large-scale continuous production of triboelectric nanogenerators is carried out through the existing production equipment,which has achieved a breakthrough in the application of triboelectric nanogenerators and has important industrial application value.