A dual-doped strategy to enhance the electrochemical performances of electropolymerized polyaniline electrodes for flexible energy storage

Abstract

We have designed a simple dual-doped strategy to boost the supercapacitive properties of polyaniline (PANi) electrodes. Specifically, dual-doped PANi (DD-PANi) electrodes are prepared via electrochemical polymerization, during which phosphoric acid and hydrochloric acid serve as dopants simultaneously. Electrochemical measurements indicate that the DD-PANi electrodes exhibit substantially improved electrochemical properties with respect to single-doped PANi electrodes (i.e., phosphoric acid-doped PANi and hydrochloric acid-doped PANi electrodes). This improvement can be attributed to the fact that dual-doped strategy changes the morphology and roughness of electropolymerized PANi films, thus leading to increased electroactive surface area and short pathway for electron/ion transport. The resultant DD-PANi electrodes exhibit high areal capacitance of 382.1 mF cm−2 at 0.5 mA cm−2, as well as ideal cycling performance (retaining 91.2% of initial capacitance after 5000 cycles). Furthermore, we have explored the feasibility of DD-PANi electrodes for high performance flexible solid-state supercapacitors. The assembled supercapacitor using DD-PANi electrodes features high mechanical flexibility, good electrochemical capacitive properties, and superior long-term stability (including deformation stability and electrochemical stability), which ensure its potential for applications in flexible energy storage devices.