Synthesis of oriented coral-like polyaniline nano-arrays for flexible all-solid-state supercapacitor

•PANI nano-array formation mechanism was proposed based on electrostatic potential surface.•Effect of PANI nano-arrays length on electrochemical performance of supercapacitor was clarified.•All-solid-state device showed excellent flexibility.•Capacity of all-solid-state supercapacitor device retained 93.9% even at 120° bending state.

The oriented coral-like polyaniline (PANI) nano-arrays for the all-solid-state supercapacitor was successfully synthesized by using a three-step galvanostatic technology in the absence template. The average diameter and length of PANI nano-rod after 6 h growing were about 30 nm and 400 nm, respectively. The formation mechanism of vertically oriented coral-like PANI nano-arrays was proposed based on the electrostatic potential surface. Compared with SO42− ions, ClO4− ions resulted in more regular surface charge distribution, which remarkably improved the order degree of coral-like PANI nano-arrays. The specific capacitance of supercapacitor made of this nano-arrays reached about 537 F/g at a current density of 3 A/g and retained about 84.8% of their initial value even in a 120° bending state, and the symmetrical all-solid-state supercapacitor device using polyvinyl alcohol (PVA/H2SO4) as solid electrolyte retained 93.9% of its initial value even in a 120° bending state. It indicates that such a PANI nano-arrays should be promising materials for the flexible and portable energy storage device.

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