Flexible supercapacitor based on three‐dimensional cellulose/graphite/polyaniline composite

Abstract

Fast charge-discharge rate and high areal capacitance, along with high mechanically stability, are the pre-requisites for flexible supercapacitors to power flexible electronic devices. In this paper, we have used three-dimensional polyacrylonitrile graphite foam as flexible current collector for electro-deposition of polyaniline (PANI) nanowires. The graphite foam with PANI was then used to fabricate symmetric supercapacitor. The fabricated supercapacitor in the three-electrode system shows a high specific capacitance (Csp) of 357 F.g−1 and areal capacitance (Careal) of 7142 mF.cm−2 in 1 M H2SO4 at current density of 80 mA.cm−2, while using two-electrode system, it shows Csp of 256 F.g−1 and Careal of 5120 mF.cm−2 in 1 M H2SO4 at current density of 100 mA.cm−2. The current density of 100 mA.cm−2 is up to 10 folds higher than reported current densities of many PANI-based supercapacitors. The high capacitance can be attributed to the spongy network of PANI-NWs on three-dimensional graphite surface which provides an easy path for electrolyte ions in active electrode materials. The developed supercapacitor shows specific energy of 64.8 Whkg−1 and a specific power of 6.1 kWkg−1 with a marginally decrease of 1.6% in Csp after 1000th cycles, along with coulombic efficiency retention of 87% in polyvinyl alcohol/H2SO4 gel electrolyte. This flexible supercapacitor exhibits great potential for energy storage application.