In situ polymerization of pyrrole on CNT/cotton multifunctional composite yarn for supercapacitors

Yarn-shaped supercapacitors are favored due to their small size, high specific capacitance, and light weight. Herein, we reported a distinctive type of ply twist yarn supercapacitor by in situ polymerization of pyrrole on carbon nanotubes (CNTs)/cotton ring spun yarns. CNTs and polypyrrole (PPy) were successfully embedded into the cotton yarns with a ply twist structure. The as-developed electrode exhibited excellent electrical conductivity (20 Ω/cm), good mechanical properties (59.8 MPa, 24.6%), a high specific capacitance of 386.5 mF/cm2 with the current density of 1 mA/cm2, and ideal cycle stability with the retention of 87.8% after 5000 cycles. Meanwhile, the assembled supercapacitor showed a power density of 278.4 μW/cm2 and an energy density of 13.21 μWh/cm2. It also presented outstanding capacitive performance under different angles. This facile ply twist method provided new possibilities for one-dimensional (1D) supercapacitor and flexible wearable electronics applications.