Synthesis of three-dimensional boron carbon nitrogen/reduced grapheme oxide broccoli as electrode material for flexible micro-supercapacitors

Scalable and cost-effective production of micro-supercapacitor (MSC) materials is crucial for the extensive application of MSCs. Thus, the two dimensional (2D) boron carbon nitride (BCN) nanosheet is first transformed into three dimensional (3D) BCN microsphere and incorporated with grapheme oxide (GO) nanosheet to construct 3D BCN/ rGO broccoli materials by a simple way. Then the 3D BCN/rGO broccoli as electrode materials are applied to MSCs through the two methods of screen printing and laser engraving. Finally, the BCN/rGO broccoli as electrode materials in MSCs by screen printing show an excellent specific capacitance of 72.2 mF cm−2 at a current density of 0.1 mA cm−2. The excellent power density and energy density is up to 1175 mW cm−2 at the current density of 2.5 mA cm−2 and 11 mWh cm−2 at a 0.1 mA cm−2. MSCs by laser engraving exhibit better performance than screen printing that the specific capacitance is up to 179 mF cm−2 which is owe to the further reduction of GO by laser. Furthermore, the 3D BCN/ rGO broccoli materials based MSCs also exhibit remarkable mechanical flexibility and cycle stability. It has been found that the capacitance reduction is negligible after bending up of device to 180° and 95% capacity retention was obtained even after 10,000 cycles. These results demonstrate the synthesis of BCN/rGO broccoli provides distinctive insights into new material toward developing flexible coplanar symmetric micro-supercapacitors, thus promoting the application of MSCs based on 3D BCN/ rGO broccoli electrode.