Direct ink printing reduced graphene oxide/KCu7S4 electrodes for high-performance supercapacitors

3D printing method based on direct ink writing (DIW) opens a novel idea for the structural design of micro supercapacitor electrode with excellent hole structure. However, at present, how to select and broaden the kinds of active materials suitable for printing is still the focus of attention. In this study, two-dimensional lamellar graphene oxide (GO) used as the binder and nano-rod KCu7S4 with excellent tunnel shuttle conductivity are used as the raw material to prepare ink suitable for 3D printing through the simple mechanical mixing. After DIW printing, the conductivity of electrode is realized after simple one-step reduction. Printed rGO/KCu7S4 electrode shows 815.83 F/g for gravimetric capacitance at 0.5 A/g, corresponding to 7.33 F/cm2, and 27.7 F/cm3 for the areal and volumetric capacitance, respectively. At a power density of 2.16 mW/cm2, the assembled symmetrical supercapacitor obtains the areal energy density of 286 μWh/cm2 and excellent cycle stability. This study reveals a simple, economical, and feasible method for the application of metal sulfide materials for DIW printing of supercapacitors and other electrochemical devices. Reduced graphene oxide and KCu7S4 are printed to fabricate electrodes for high performance supercapacitors.