ABASTRAT: In the present work, a self-standing conductive polyaniline/polyvinyl alcohol (PANI/PVA) hydrogel (CPH_PA/SA) co-doped with phytic acid (PA) and sulfuric acid (SA) has been synthesized by chemical oxidation polymerization. The anisotropic tubular structure imparted by SA and the three-dimensional microporous structure imparted by PA enable CPH_PA/SA electrodes to exhibit excellent mechanical and electrochemical performances. The CPH_PA/SA electrodes showed high specific capacitance of 849 F/g at a current density of 0.5 A/g and outstanding cycling stability of 83% capacitance retention after 10000 charge/discharge cycles at a current density of 1.5 A/g, which was superior to that of single-doping hydrogel electrode. An all-hydrogel flexible supercapacitor device was fabricated by CPH_PA/SA hydrogel electrodes and PVA/H₂SO₄ hydrogel electrolyte to further explore the potential application prospects of the synthesized hydrogel electrodes in flexible devices. The assembled supercapacitor exhibited a high energy density of 26.1 Wh/kg and a power density of 125 W/kg. The sensor was designed based on the CPH_PA/SA hydrogel, which can detect tiny signals relevant to the human body with subtle distortion. This study provides a new direction for the preparation of novel energy storage and wearable smart sensors and human health monitoring devices with flexible hydrogel electrode materials.

Keywords: polyaniline, co-doping, supercapacitors, electrochemical properties, sensor.