Direct Assembly of 3D-BCN Microspheres as a Microsupercapacitor Electrode for Wearable Energy Storage

Scalable and cost-effective fabrication of three-dimensional (3D) boron carbon nitride (BCN) microspheres was first demonstrated by hydrothermal and annealing methods. In particular, the specific surface area of 3D-BCN-4 reached 1390.12 m(2) g(-1) and had a high hierarchical pore structure. An all-printed solid-state flexible microsupercapacitor (MSC) based on 3D-BCN-4 microspheres as an electrode material was fabricated for the first time by a screen printing method, which also provided efficacious properties. The single MSC areal capacitance reached 41.6 mF cm(-2). Furthermore, the remarkable mechanical flexibility was also achieved for the device with evidence that no obvious capacitance loss occurred even upon bending to 180 degrees, and the device had a 93.3% capacitance retention after 1000 cycles. In addition, the maximum energy density reached 0.00832 mW h cm(-2), and the highest power density was 2 mW cm(-2). These results show the synthesis of 3D-BCN by a facile and effective method with excellent electrochemical performance, which should provide a promising direction to wearable energy storage devices.