Flexible screen-printed supercapacitors with asymmetric PANI/CDC–AC electrodes and aqueous electrolyte

Abstract

We report the fabrication and electrical performance of screen-printed flexible supercapacitors (SCs) based on activated carbon (AC) and polyaniline (PANI)/carbide-derived carbon (CDC) composite electrodes, and neutral aqueous electrolytes. The devices are entirely constructed from safe, low-cost, and non-toxic materials, fabricated through a mass production capable screen printing process, and fully disposable with normal household waste. Symmetric and asymmetric cells with a thin planar face-to-face structure were fabricated on polyethylene terephthalate substrate, using eco-friendly chitosan binder based electrode inks, and printed graphite current collectors. The asymmetric cell configuration, with a PANI/CDC positive electrode and an AC negative electrode, demonstrated significantly improved electrochemical performance, through increased operating voltage, energy density and power density, improved cyclic stability and rate capability, and decreased equivalent series resistance (ESR) and leakage current, compared to previously reported symmetric PANI/CDC SCs. The fabricated asymmetric devices had an average capacitance of 250–270 mF, ESR of 20–23 Ω, and leakage current of 140–150 µA, depending on the PANI/CDC variant used. Energy densities of 4.8 Wh kg−1 and 4.9 Wh kg−1, power densities of 1.6 kW kg−1 and 1.5 kW kg−1, and capacitance retention rates of 93% and 97% after 2000 charge–discharge cycles, were achieved with PANI/CDC (10:1) and (30:1) variants, respectively.