Homogeneous epoxy resin/phytic acid gel-derived carbon composite and its high energy density for supercapacitor

Abstract

The composites of two or more metal oxides/sulfides have been prepared and widely used in energy storage including battery and supercapacitor. However, the composite of two activated carbon component is seldom involved. Moreover, those solid carbon sources block their contact with another carbon source and suppress the construction of rich interfaces between two components in carbon composite. In this work, an epoxy resin (EP)/phytic acid (PA) homogeneous gel is prepared by combining the solvation/de-solvation process at 80 °C and the gelation process at different temperatures (120 °C, 150 °C and 180 °C) so as to supply the rich interfaces between epoxy resin/phytic acid. Subsequently, hydrogen bond crosslinks of hydroxyl groups on the surface of the epoxy resin chains with the phosphate groups of liquid phytic acid as well as ester crosslinks are constructed. Lastly, uniform carbon composites with rich interfaces between the two components from EP and PA are acquired. The optimized activated carbon composite, i.e., AEPC-150 which is gelled at 150 °C possesses micropore-dominant porous structure and thus a high specific surface area of 1642 m² g⁻¹. In addition, AEPC-150-based electrode exhibits a superior capacitance of 435.2 F g⁻¹ at 1 A g⁻¹, in which a high pseudocapacitance domain of 37.2% at 5 mV s⁻¹ (vs. 15.6% for AEPC-120, 11.4% for AEPC-180). The symmetric supercapacitor (SSC) of AEPC-150//AEPC-150 delivers an outstanding energy density of 35.58 Wh kg⁻¹ at a power density of 150 W kg⁻¹, and 20.83 Wh kg⁻¹ even at 3750 W kg⁻¹.