Soft fully-printed rGO/Fe2O3-based supercapacitors for wearable electronics

Flexible supercapacitors have immense promise for powering wearable electronics, but they are constrained by a lack of efficient preparation methods and low energy density. Herein, reduced graphene oxide (rGO)/Fe2O3 composite was synthesized for the active material of screen-printing functional inks via a simple hydrothermal method, which possesses a high specific capacitance of 703.91 F g-1 (527.93 C g-1) at 1 A g-1. The rGO/Fe2O3- based functional inks with excellent dispersibility and printability were formulated in ethyl cellulose (EC) -ethanol system. The fabrication of performance-controlled screen-printed electrodes was achieved by over-printing for the first time. Furthermore, the integratable and pattern-customizable all-printed flexible super -capacitors (FSCs) are fabricated by using rGO/Fe2O3-based printed electrodes with different printed layers. The as-prepared rGO/Fe2O3-based FSCs deliver remarkable areal capacitances of 27.12-119.37 mF cm-2 at 0.1 mA cm-2 and significant energy densities of 2.4-10.6 mu Whcm- 2 at a power density of 0.04 mW cm-2. In addition, rGO/Fe2O3-based device exhibits exceptional flexibility with no performance degradation after 200 cycles of bending. The directly screen-printed integrated rGO/Fe2O3-based printed FSC array provides a stable energy supply to the thermometer, which has promising application prospects in the field of wearable energy storage.

Automated summary

This study presents a simple hydrothermal method to synthesize rGO/Fe2O3 composite, which can be used as the active material in screen-printing functional inks. The functional inks show excellent dispersibility and printability in an EC-ethanol system. By over-printing, performance-controlled screen-printed electrodes were successfully fabricated. In addition, flexible supercapacitors (FSCs) with different printed layers were achieved using rGO/Fe2O3-based printed electrodes, exhibiting remarkable areal capacitances and significant energy densities. The flexibility and stability of the device were also demonstrated. The directly screen-printed integrated rGO/Fe2O3-based printed FSC array provides a stable energy supply and has promising application prospects in wearable energy storage.