Electroactive biopolymer/graphene hydrogels prepared for high-performance supercapacitor electrodes

Abstract

Lignosulfonate (Lig), a biopolymer derivative, is a good candidate to be used as supercapacitor electrode material because of its electroactive components. The methoxy and phenolic functional groups in Lig can convert to quinone groups through the redox process and function for energy storage. However, it is difficult to directly utilize Lig’s electroactivity, because of its insulativity. Herein, a composite of Lig/graphene hydrogel (Lig-GH) was fabricated from a mixture of Lig and graphene oxide (GO) via convenient hydrothermal process. It was found that the hydrothermal process temperature played a significant role in forming Lig-GH. In the present work, the effect of the mass ratio of Rm (GO: Lig) on the electrochemical properties of composite hydrogels was discussed. The results disclosed that the Lig-GH prepared at a mass ratio of Rm=3:4 and temperature of 180°C exhibited excellent electrochemical performance. The as-prepared hydrogel possessed high specific capacitance of 549.5Fg−1 at a current density of 1Ag−1 in 0.1M HClO4 electrolyte. It also showed excellent cycling stability: 83.7% capacitance retention after 1000 cycles at 20Ag−1. This work provides an innovative strategy to prepare high performance Lig-GH supercapacitor electrodes material by introducing renewable and inexpensive biopolymers.