Fabrication of Polypyrrole/Reduced Graphene Oxide/Silk as a High-Performance Electrode for Fiber-Shaped Flexible Supercapacitor

Fiber-shaped supercapacitors (FSSCs), as a very new variety of flexible power source, are strongly needed for smart electronics, but the preparation still remains challenging. In this study, using silk fiber (SF) as a linear substrate, reduced graphene oxide (rGO) as an electron transport enhancing layer, and polypyrrole (PPy) as a pseudocapacitive wrapping phase, a PPy/rGO/SF ternary electrode is developed by a facile ‘dipping and drying’ and in situ polymerization. In three-electrode, the product depicts an attractive length specific capacitance of 85.9 mF cm^− 1 at 0.5 mA cm^− 1, which represents a novel performance record in the SF based flexible electrodes, and is also even higher than a lot of carbon yarn and metal fiber based electrodes. The quasi-solid-state FSSC device, PPy/rGO/SF//PPy/rGO/SF, shows a high energy density of 2.2 µWh cm^− 1 at 25.9 µW cm^− 1, and an outstanding power density of 438.8 µW cm^− 1 at 0.4 µWh cm^− 1. Moreover, good capacitive stability and mechanical flexibility with capacitance retentions of 75% after 4000 charging/discharging cycles and 94% at bending degrees from 0 to 150° are presented. Our study supplies a good example for the preparation of high-performance SF electrode, which may contribute to the rapid development of FSSCs.