Polypyrrole-coated carbon nanotube/cotton hybrid fabric with high areal capacitance for flexible quasi-solid-state supercapacitors

To achieve high performance flexible supercapacitors, flexible electrodes with good electrochemical performance, high stability, and superior mechanical property are strongly needed. With their light weight, intrinsically mechanical flexibility, and the unique textile structure, fabrics of polymeric fibers hold great promise as an ideal substrate for building flexible electrodes. However, the exploration of such electrodes that can be prepared in a facile and scalable way, and simultaneously have a high areal capacitance is still a challenge. Here, we report a polypyrrole (PPy)-coated carbon nanotube/cotton hybrid fabric, which are fabricated by a highly facile and scalable knitting and chemical polymerization process, to address above issue. Remarkably, the resulting fabric with a PPy mass loading of 13.2 mg cm−2 exhibits a high areal capacitance (4192 mF cm−2 at 5 mA cm−2) and good rate capability (50% capacitance retention at 100 mA cm−2) as well as excellent cycling stability (95% capacitance retention after 5000 cycles). The quasi-solid-state symmetric supercapacitor assembled with this fabric electrodes delivers an areal capacitance of 1947 mF cm−2 at 5 mA cm−2, a maximum energy density of 0.17 mWh cm−2 and a maximum power density of 25.6 mW cm−2. Our study therefore provides a new opportunity for developing flexible supercapacitors with high performance and scalable production.