Cold spray direct writing of flexible electrodes for enhanced performance triboelectric nanogenerators

Abstract

Triboelectric nanogenerator (TENG) is an emerging energy harvesting device to effectively harness various mechanical energy sources. In TENG technology, polymers are of particular interest as tribo-negative materials owing to their unique properties (e.g., charge storage capability, impact resistance, flexibility, low cost, recyclability, etc.). Despite significant advances, one major challenge for TENG is to develop high-performance back electrodes that are conformably attached to the tribo-negative polymer substrates to fully exploit the potential of TENG in energy harvesting. To this end, the present study is aimed to employing direct “cold spray” particle deposition as just one-step fabrication method for high-performance electrodes on flexible polymers. In this regard, Tin (Sn) particles are directly written on the polymer (PET) surface by cold spraying to achieve conformal electrodes with high-adhesive strength and stable electrical conductivity. The resulting electrodes are thoroughly characterized in terms of microstructure, adhesion strength, and electrical performance. Arc-shaped TENG devices with both traditional aluminum (control) and cold-sprayed Sn electrodes are fabricated, followed by evaluating the TENGs' performance. Owing to the strong adhesion and micro-roughness (i.e., Ra = 4.865 μm) of the Sn electrodes, electricity generation performance was found to be improved by ≈2.4 folds as compared to the control TENG. The TENG with Sn electrode can generate an open-circuit output voltage of up to 243 V with a maximum output power of 130 mW/m2, thereby indicating the promising potential of the cold spray technique in TENG technology.