A Simple Route to Fabricate Ultralong and Uniform Polypyrrole Nanowires with High Electrochemical Capacitance for Supercapacitor Electrodes

This work demonstrated a straightforward strategy to fabricate ultralong interconnected polypyrrole (PPy-GS) nanowires with a gemini surfactant (GS) as a soft template and dopant. Pure PPy particles and a PPy nanowire doped with CTAB (PPy-CTAB) were prepared for comparison. The results showed that the electrochemical performances, conductivity, and morphology of PPy-GS could be significantly changed by changing the concentration of GS in the aqueous phase owing to the different self-assembly behaviors. When the molar ratio of pyrrole, APS, and GS was 1:1:0.4, an interconnected ultralong and uniform PPy-GS nanowire with the largest surface area, the smallest average pore size, the lowest contact angle, and the highest conductivity can be obtained, resulting in the formation of effective electrolyte transport channels and faster electron transport pathways. Compared with pure PPy particles and the PPy-CTAB nanowire, the incorporation of GS significantly enhanced the conductivity and specific capacitance of PPy-GS-40%. The conductivity of PPy-GS-40% was up to 13.54 S/cm compared with 1.17 S/cm for PPy particles and 3.84 S/cm for the PPy-CTAB nanowire. Also, the highest specific capacitance of PPy-GS reached up to 556 F/g at 1 A/g compared with 233 F/g for PPy particles and 397 F/g for the PPy-CTAB nanowire. A total of 85.4% of the initial capacitance was retained even after 2000 cycles at 1.0 A/g. The energy density and power density of the PPy-GS-40% symmetrical supercapacitor were 49.4 Wh/kg and 400 W/kg, respectively. The good electrochemical properties of the PPy-GS electrode suggest a tremendous potential in the high-performance electrode not only for supercapacitors but extensively for various energy storage applications.