Synergies of polypyrrole and carbon nanotube on carbon fiber fabrics for improving electrochemical and mechanical properties of structural supercapacitor electrodes

Abstract Structural supercapacitors (SSCs) are a promising solution for reducing the weight of structures. In order to improve the electrochemical performance of carbon fiber (CF) electrodes, a new technique for carbon fiber electrodes modified with polypyrrole (PPy) and carbon nanotubes (CNTs) with friendly preparation methods was developed. The mixture of PPy and CNT produced a significant synergistic effect in increasing the capacitance of the electrode. PPy/CF electrode was optimized by adjusting parameters. The areal capacitance of the CNT‐PPy/CF electrode achieves 1789.84 mF/cm² at a scanning speed of 10 mV/s, which is 159 times higher compared with the CF electrode. Furthermore, the CNT‐PPy/CF electrode exhibits good electrical conductivity, mechanical flexibility, and cycle stability. In terms of mechanical properties, the monofilament tensile strength of CNT‐PPy/CF is improved by 9.5% compared to CF after treatment at 550°C. In addition, the SSC was fabricated using two pieces of electrodes, the PEGDGE/EMIMTFSI/LiTFSI as the electrolyte and a piece of basalt fiber fabric as the separator. The capacitance of SSC with CNT‐PPy/CF as electrodes is 38 times higher than that with CF as electrodes, and the power density is 1.23 mW/cm⁻³ at the energy density of 18.36 μWh/cm⁻³. The results demonstrate the CNT‐PPy/CF electrode provides an excellent electrode for the high‐performance SSC. Highlights A novel modification method for CF electrodes was developed using CNTs and PPy. The synergistic effect of PPy and CNT is exhibited. CNT‐PPy/CF provides excellent electrodes for the high‐performance SSC. PPy synthesized with dopant NaSSA exhibits excellent electrochemical performance. CNT‐PPy/CF exhibits excellent electrochemical and mechanical performance.