Three-dimensional micro/nano-interconnected scaffold graphene-based micro-supercapacitors with high electrochemical performance

Micro-supercapacitors (MSCs) have emerged as one of the most promising power supply candidates to meet the ever-increasing requirement for various miniaturization application scenarios due to the merits of high power density, long life span, superior rate capabilities and ease of maintenance and integration. However, wide applications of MSCs were greatly hindered due to the poor energy density. In this regard, designing and constructing three-dimensional (3D) architecture electrodes have been considered an effective strategy to improve the energy density of MSCs, which secures enhanced electrochemical active sites and facilitates ions kinetics for efficient charge storage capability. Herein, high-performing MSCs have been achieved with a graphene-based electrode of a rational 3D micro/nano-interconnected scaffold, in which the robust 3D architecture can be effectively regulated by controlling the amount of carbon nanotubes (CNTs). Electrochemical mechanism and theoretical simulation results reveal that enhanced electrolyte ion accessible sites and facilitated ion kinetics can be ensured since the homogeneous electric streamlines distribution in the 3D micro/nano-interconnected scaffold. As expected, the resultant MSCs possess an outstanding electrochemical performance with an areal capacitance as high as 53.49 mF cm−2 under the pack of gel-based electrolytes, delivering a power density of 25 mW cm−2 and an energy density of 8.82 μWh cm−2. Moreover, the MSCs show superior long-term stability with 99% retention after 20 000 cycles, which is beyond most reported 3D graphene-based MSCs. The 3D micro/nano-interconnected scaffold electrodes might provide a method to enhance the electrochemical performance of micro-scale power sources for the applications of micro-devices.