Wearable supercapacitors based on conductive cotton yarns

High-performance fiber- and yarn-shaped supercapacitors based on commonly available fiber materials and production technologies are needed to meet the fast developing electronic textile market. In this investigation, natural cotton and stainless steel fibers (SSFs) are blended to form a conductive yarn for constructing novel high-performance two-ply yarn supercapacitors. The supercapacitors show very high areal capacitance, energy density, flexibility and electrochemical stability. The excellent performance is attributed to the high porosity, high conductivity and distributive metal fiber network formed in the blended yarn, coupled with the high electrochemical efficiency of the nanostructured polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) pseudocapacitance materials. The SSF-cotton blended yarn is economic to produce and retains the flexibility of a normal cotton yarn that is commonly used in apparel textiles. This greatly facilitates the integration of the two-ply yarn supercapacitor into electronic textiles.