Ultrahigh\nSurface\nArea Hierarchically Porous Carbon\nMaterials from Polyacrylamide–Cellulose Hydrogel for High-Performance\nSupercapacitors

Abstract

High\nsurface area, hierarchically micro/mesoporous carbon\nmaterials\nwith interconnected pore structures have significant potential as\nelectrode materials for high-performance supercapacitor applications.\nHere, we present the synthesis of ultrahigh surface area hierarchically\nporous carbon materials, prepared by potassium carbonate (K₂CO₃) activation of polyacrylamide–hydroxy propyl\ncellulose (PAM–HPC) hydrogel at high temperatures (500–900\n°C), and their energy storage performances in two- and three-electrode\ncell setup. The carbon material obtained by carbonization of the PAM–HPC\nhydrogel at 800 °C exhibits an ultrahigh surface area of 3387.2\nm² g^–1 with a large pore volume of 1.963\ncm³ g^–1. The electrode prepared using\nthis material demonstrated excellent supercapacitance performance\nin the three-electrode system, achieving a high specific capacitance\nof 545.5 F g^–1 at 1 A g^–1 current\ndensity with superior rate capability and an outstanding cycling stability\nof 96.3% after 5000 charge–discharge cycles. Furthermore, the\nassembled symmetric supercapacitor device constructed by using this\nmaterial showed a high specific capacitance of 102.5 F g^–1 at 0.5 A g^–1. It delivers a high energy density\nof 17.2 W h kg^–1 at the power density of 550 W kg^–1, and a superior cycling stability of 94.2% after\n5000 consecutive charge–discharge cycles. The electrochemical\nproperties reported here indicate that hierarchically porous carbons\nobtained from PAM–HPC hydrogels are promising materials for\nhigh-performance supercapacitor applications.