Thermal effect on the pseudocapacitive behavior of high-performance flexible supercapacitors based on polypyrrole-decorated carbon cloth electrodes

Abstract

With the ongoing advance of flexible energy storage products for commercial portable electronics application, the fundamental comprehension of the temperature-dependence for supercapacitors is in urgent demand. Although polypyrrole (PPy) has been extensively employed as electrodes for supercapacitor systems, their electrochemical response to extreme thermal environments is rarely discussed. In this work, PPy was rationally constructed on the surface of carbon cloth (CC) as electrodes and a type of high-performance flexible symmetric supercapacitor was assembled with a PVA-H₃PO₄ gel electrolyte. The electrochemical performance of the supercapacitors was systematically investigated at various surrounding temperatures from 0 °C to 60 °C using cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy measurements. The results demonstrated that the areal specific capacitance of the CC/PPy supercapacitor at 0.5 mA cm⁻² increased from 52.91 mF cm⁻² to 75.08 mF cm⁻² and the internal resistance fell by 71.4% when the operating temperature rose from 0 °C to 60 °C. Moreover, cycling stability dropped and the self-discharge behavior accelerated in the supercapacitors with the gradual increase in the external temperature. This study provides a fundamental understanding of the temperature-dependent pseudocapacitive performance of PPy-based flexible supercapacitors, which gives a valuable reference for energy storage system applications.