Deposition of ZIF-67 and polypyrrole on current collector knitted from carbon nanotube-wrapped polymer yarns as a high-performance electrode for flexible supercapacitors

Polymeric fiber fabrics with inherent mechanical flexibility, lightweight and porous textile structure are highly attractive as an ideal substrate for building flexible electrodes. However, their insulating nature limits their direct application as current collector. Here, we designed and fabricated a flexible conductive fabric from polymer yarns. This was achieved through wrapping polymer yarns with a carbon nanotube (CNT) cylinder, which was continuously prepared from a floating catalyst chemical vapor deposition process, and a subsequent knitting process. The derived CNT-wrapped polymer yarn fabric (CPYF) could directly serve as current collector/substrate to load zeolitic imidazolate framework-67 (ZIF-67) and polypyrrole (PPy) through in-situ growth and chemical polymerization. The resultant CPYF-ZIF-67-PPy displayed a maximum areal capacitance of 2308.8 mF cm-2 at 0.5 mA cm-2. Moreover, the assembled supercapacitor achieved a maximum areal energy density of 112 μW h cm-2 at the power density of 201.5 μW cm-2. Meanwhile, the device demonstrated an extraordinary flexibility with stable electrochemical properties after 5000 cycles of bending and 1000 cycles of stretching. This work therefore offers a new strategy that can be used to develop flexible conductive fabric for flexible supercapacitors.