Zinc ion coordination doped polyaniline electrode for high performance supercapacitors

Abstract

Polyaniline (PANI) is a promising supercapacitor electrode material due to its inherent electrical conductivity and high specific capacitance. However, the molecular structure of PANI is susceptible to destroyed due to the volume expansion and contraction during repetitive charging and discharging processes, leading to the decrease of the cycling stability. Therefore, enhancing the electrochemical cycling stability of PANI electrode materials is the key technologies for PANI application in supercapacitors. In this study, a one-step electrodeposition method achieved zinc ion coordination doping of polyaniline on a carbon cloth substrate. Coordination of zinc ions with the imine groups on the polyaniline chain enhanced the interaction between the PANI molecular chains, significantly improving the cycling stability and electrochemical properties of PANI electrode. PANI-Zn_0.10 has an area-specific capacitance of up to 2665 mF·cm⁻² at 5 mA·cm⁻². PANI-Zn_0.10–13.6 electrodes with a mass loading up to 13.6 mg·cm⁻² achieved an area-specific capacitance of 3549 mF·cm⁻² at a current density of 5 mA·cm⁻². The assembled flexible symmetric supercapacitor exhibits a high energy density of 50.1 Wh·kg⁻¹ (269.3 μWh·cm⁻²) at a power density of 443.3 W·kg⁻¹ (2400 μW·cm⁻²). The assembled button-type symmetric supercapacitor exhibited remarkable capacitance retention of 87.49 % even after 5000 cycles at 5 mA·cm⁻². It has been shown that PANI-Zn coordination polymers have excellent electrochemical properties and great potential for application in the field of energy storage devices.