Wood-Derived Monolithic Ultrathick Porous Carbon Electrodes Filled with Reduced Graphene Oxide for High-Performance Supercapacitors with Ultrahigh Areal Capacitances

A monolithic ultrathick and dense carbon electrode with high specific surface area and high hydrophilicity is fabricated for high-performance supercapacitors with ultrahigh areal capacitance by infiltration of graphene oxide inside the aligned pores of the wood followed by lyophilization, carbonization, thermal reduction at 800 degrees C, and activation with KOH. The porous and vertical microchannels in the wood-derived carbon facilitate the transport of ions and electrons, while the presence of reduced graphene oxide provides the electrode with high specific surface area, high electrochemical stability, and compactness. Benefiting from the efficient pores resulted from the KOH activation, the monolithic electrode exhibits a high specific surface area of 1049.9 m(2) g(-1) with an enhanced permeability, and remains its primary structure as a freestanding electrode without the use of conductive additives or binders. Consequently, the directly sliced pellet electrode with a thickness of 2.2 mm delivers a high areal capacitance of 26.6 F cm(-2) at a current density of 1 mA cm(-2) in 6 M KOH electrolyte. The resultant symmetrical supercapacitor with a KOH gel electrolyte reaches an energy density of 0.91 mWh cm(-2) and a maximum power density of 11.90 W cm(-2).

Automated summary

A monolithic ultrathick and dense carbon electrode with high specific surface area and high hydrophilicity is developed for high-performance supercapacitors with ultrahigh areal capacitance by infiltrating graphene oxide into aligned wood pores. This unique electrode structure, combined with reduced graphene oxide and efficient pores from KOH activation, results in a freestanding electrode with high capacitance and energy density. The symmetrical supercapacitor using this electrode demonstrates excellent performance with a high energy density and power density.