Various morphologies of polyaniline (PANI) nanostructures (i.e., nanospheres, nanofibers, vertical nanowires, and cauliflower-like) were synthesized on the surface of reduced graphene oxide (RGO)/cotton fabric (CF) electrode through in situ chemical polymerization method. The synthesis parameters, such as oxidant/monomer (O/M) molar ratio and oxidant type, were changed to investigate the effect of surface morphology on supercapacitive performance of PANI/RGO/CF electrode. Also, the effect of the de-doping process of doped PANI on the electrochemical performance of the PANI/RGO/CF electrode was evaluated. It was found that the O/M ratio and oxidant type strongly affect the nucleation rate of PANI nanostructures, leading to developing electrodes with different surface morphologies providing different electrical conductivities and energy storage performances. The de-doping process was found as an unfavorable treatment, yielding the decreased conductivity and capacitive performance of the PANI/RGO/CF electrode. The synthesized fully doped PANI on the surface of RGO/CF using ammonium persulfate as the oxidant at an O/M ratio of 0.5 created an electrode with the vertical PANI nanowires morphology providing the highest electrochemical performance. The all-solid-state flexible symmetric supercapacitor assembled using this electrode delivered a remarkable energy density of 35.9 Wh kg⁻¹ (at a power density of 130.5 W kg⁻¹) and retained 91.5% of initial specific capacitance after 1000 mechanical bending cycles. This supercapacitor possessed good rate capability and excellent cycling stability (97.3% retention after 1000 charge–discharge cycles). The findings of this research will lead to a better design of polyaniline-based textile electrodes for the next-generation wearable supercapacitors.

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