Highly conductive rubber-based electrode with a robust wrinkled mesh-like copper coating for stretchable triboelectric nanogenerator

Stretchable triboelectric nanogenerators (TENGs) have gained increasing attention for their potential applications in wearable electronics. However, the fabrication of metal-coated flexible electrodes with a robust metalpolymer interface, high conductivity, and stretchability remains challenging for stretchable TENGs. Herein, a stretchable triboelectric nanogenerator (TENG) was designed using a highly conductive natural rubber (NR) electrode with a wrinkled mesh-like copper coating, which was chemically plated onto its surface by polymerassisted metal deposition (PAMD) technology. To enable the PAMD process, a layer of polyacrylic acid (PAA) polymer brushes was first grafted onto the NR surface. This could not only assist the chemical plating but also improve the interfacial adhesion between the copper coating and the NR substrates. More importantly, the PAA layer facilitated the interconversion between the wrinkled structure and mesh-like structure of the copper coating during stretching cycles to ensure its conductivity and mechano-electrical stability. With this intrinsically stretchable rubber-based electrode, TENG devices were designed in a contact-separation configuration, which could effectively harvest mechanical energy in both pressing and stretching modes and show excellent electrical output performance. Notably, the rubber-based TENG could work stably at 100 % strain and produce a maximum power density of 0.14 mW/m 2 at the resistance load of 3 x10 7 ohm. Therefore, the stretchable rubber-based TENG in this work demonstrated a potential solution to flexible micromechanical energy harvesters for wearable devices.