Ultrahigh Surface Area Hierarchically Porous Carbon Materials from Polyacrylamide–Cellulose Hydrogel for High-Performance Supercapacitors

High surface area, hierarchically micro/mesoporous carbon materials with interconnected pore structures have significant potential as electrode materials for high-performance supercapacitor applications. Here, we present the synthesis of ultrahigh surface area hierarchically porous carbon materials, prepared by potassium carbonate (K2CO3) activation of polyacrylamide–hydroxy propyl cellulose (PAM–HPC) hydrogel at high temperatures (500–900 °C), and their energy storage performances in two- and three-electrode cell setup. The carbon material obtained by carbonization of the PAM–HPC hydrogel at 800 °C exhibits an ultrahigh surface area of 3387.2 m2 g–1 with a large pore volume of 1.963 cm3 g–1. The electrode prepared using this material demonstrated excellent supercapacitance performance in the three-electrode system, achieving a high specific capacitance of 545.5 F g–1 at 1 A g–1 current density with superior rate capability and an outstanding cycling stability of 96.3% after 5000 charge–discharge cycles. Furthermore, the assembled symmetric supercapacitor device constructed by using this material showed a high specific capacitance of 102.5 F g–1 at 0.5 A g–1. It delivers a high energy density of 17.2 W h kg–1 at the power density of 550 W kg–1, and a superior cycling stability of 94.2% after 5000 consecutive charge–discharge cycles. The electrochemical properties reported here indicate that hierarchically porous carbons obtained from PAM–HPC hydrogels are promising materials for high-performance supercapacitor applications.