Anisotropic tribology and electrification properties of sliding-mode triboelectric nanogenerator with groove textures

Sliding-mode triboelectric nanogenerator (S-TENG) is based on the coupling of triboelectrification and electrostatic induction, converting electrical energy from sliding motion. Introducing micro-textures into the sliding surface, and adjusting the angle between the texture and sliding direction (direction angle) may achieve performance anisotropy, which provides novel ideas for optimizing the tribology and electrification performance of S-TENG. To guide the performance optimization based on the anisotropy, in this paper, groove micro-textures were fabricated on the surface of S-TENG, and anisotropic tribology and electrification performance were obtained through changing the direction angle. Based on the surface analysis and after-cleaning tests, the mechanism of the anisotropy was explained. It is shown that the anisotropy of friction coefficient can be attributed to the changes of texture edge induced resistance and groove captured wear debris, while the voltage anisotropy is due to the variations of debris accumulated on the sliding interface and the resulting charge neutralization. Among the selected 0°–90° direction angles, S-TENG at angle of 90° exhibits relatively small stable friction coefficient and high open-circuit voltage, and thus it is recommended for the performance optimization. The open-circuit voltage is not directly associated with the friction coefficient, but closely related to the wear debris accumulated on the sliding interface. This study presents a simple and convenient method to optimize the performance of S-TENG, and help understand the correlation between its tribology and electrical performance.