PEDOTS:PSS@KNF Wire‐Shaped Electrodes for Textile Symmetrical Capacitor

Abstract

represent a more reliable, safer, and longer lifecycle alternative. A number of fibers made of graphene, carbon nanotubes, conductive polymer and, more recently, MXenes were successfully obtained by wet-spinning technique and investigated as 1D electrodes for wearable supercapacitors. [17][18][19][20][21][22][23][24][25][26][27][28][29] However, these materials usually involve complex procedure for their synthesis, harmful dispersant solvent or post-treatment steps to produce fibers with sufficient mechanical resistance and electrochemical performances. Aramid nanofibers (ANFs) have been recently proposed as a new nanoscale building block to design new composite materials. [30] Contrary to standard route based on monomer polymerization, ANFs can be easily and quickly obtained through top-down approach by dissolution of aramid polymeric chains and then re-assembled in macroscopic fibers or film by solution processing. [30,31] Aramid polymer is well-known for its mechanical strength but it's not electrically conductive and must be loaded with conductive fillers to achieve electronic transport. Up to date, ANFs have been mainly investigated as filler for polymers reinforcement, [32,33] matrix for multi-purpose membranes, [34][35][36][37] thermal shields, [38,39] and even additive for separators and solid-state electrolyte for Li-ion batteries. [40,41] However, despite the good wet-spinnability of KNF dispersions, only poor attention was paid to the employment of ANFs for making FSCs. In previous work, Cao et al. fabricated fibers with core-shell structure by co wet-spinning a core carbon nanotube dispersion and a sheath ANFs dispersion. [42] The symmetrical FSCs obtained by infiltration with H 3 PO 4 /PVA gel electrolyte showed a remarkable linear capacity up to 0.75 mF cm −1 . Wang et al. loaded graphene nanoplatelets (GNPs) to a ANF dispersion to obtain a ANFs/GNPs composite wire-shaped electrodes by coagulation in a water/acetic acid solution. [43] However, their results showed that GNPs interfered with the ANFs coagulation by hydrogen bonds restoration between terephthalamide units resulting in a consistent decrease of the tensile strength at high GNPs incorporation in the ANFs matrix.In this work, PEDOT:PSS@KNFs composite fibers were produced by a simple two-step process involving the nanofibrillation of Kevlar to Kevlar nanofibers (KNF), wet-spinning of the KNF fiber and the following soaking into a PEDOT:PSS aqueous dispersion. In this way, electrically conductive fibers were obtained due to the conductive PEDOT:PSS chains percolation keeping almost unaltered the mechanical resistance of the KNF matrix. The PEDOT:PSS@KNF fibers were flexible, knittable and sewable, and by coupling adjacent two fibers, a symmetric FSC couldThe emerging wearable electronics and e-textiles have motivated tremendous interests in textile energy storage microdevices. Among them, fiber-shaped capacitors (FSCs) offer unique properties because of their 1D configuration and reliable energy storage. In recent years, many works focused o...