Fabrication of triboelectric nanogenerator with textured surface and its electric output performance

Contact electrification between insulators, manifesting as static or triboelectricity is a well-known effect. The triboelectric nanogenerator (TENG) which is based on the contact triboelectricification and electrostatic induction provides a promising route for harvesting ambient mechanical energy and converting it into electric energy. The TENG which is due to its unique properties such as simple structures, low cost, high electric density etc., can offset or even replace the traditional power source for small portable electronics, sensors and so on. So far, the influence of factors on the output performance of TENG is still trapped in unsettled questions and under debate. In this paper, we prepare several textured polydimethylsiloxane (PDMS) films with micro rod array by model method and fabricate a TENG with a size of 2222 mm. The electric generation can be achieved with a cycled process of contact and separation between a polymer and metal electrode (PDMS and aluminum respectively in this study). Several influences as the surface structure and external load on the electrical output of the TENG are systematically studied by integrating use of experimenal tests and ANSYS simulation. Results show that the existence of micro rod array on the PDMS films effectively enlarges the contact area and provides more surfaces for charge storage and hence improve the output performance of TENG. When keeping the external load constant, the output increases with decreasing distance between micro rods. When the external load is 5 N and the distance is 15 m, the average output voltage and current as high as 88 V and 15 A can be achieved respectively, which is 1.5 times higher than the output generated when the distance is 50 m. The electrical output increases quasilinearly with the increase of the external load. Simulation results show that the micro rods of PDMS films are mainly compressed by normal load, which results in a bigger diameter of micro rods. The deformations of PDMS substrate leads to the lateral friction between the micro rods and the upper electrode, which produces more charges because of the friction. For 5 N normal load, the deformations of PDMS substrate and micro rods contribute to the sum of displacement vector and the deformations along Z-axis are 32.7 m and 21.3 m respectively, and are 4.96 and 5.04 times higher than the deformation at the load of 1 N. All the results in an enlarging surface area and the larger output correspondingly. Not only does this work present a new type of generator with micro rods on the PDMS surface, which can be an effective method to improve the electrical output of TENG, but also offers a unique point of view for further understanding of the working principle of TENG.