B/N co-doped carbon nanosphere frameworks as high-performance electrodes for supercapacitors†
Energy storage devices capable of high power outputs currently attract much research interest. An example is supercapacitors, which show both high capacitance and sustained cycling ability. However, their electrodes, especially those based on carbon materials, often suffer from either low capacitance at high current density or poor durability after many cycles. Here we report a novel boron/nitrogen co-doped carbon nanosphere (B/N–CNS) framework that is simply prepared by annealing boron oxide, ammonium chloride, and glucose. The resulting B/N–CNS framework exhibits an ultra-high specific capacitance of 423 F g−1 at 0.2 A g−1 and excellent rate capability of up to 125 F g−1 at 50 A g−1. The improved performance is ascribed to its interconnected framework of nanospheres and B/N co-doping. In addition, unlike most carbon materials, this framework displays exceptional stability, showing no capacitance fading at 10 A g−1 after 30 000 cycles. Furthermore, an all-solid sandwich-structured symmetric supercapacitor with B/N–CNS framework electrodes can power a light emitting diode, demonstrating its practicability as a fully integrated energy storage device. The facile synthesis strategy and impressive capacitive performances of B/N–CNS framework make this material significantly promising in the fabrication of novel electrode materials for energy storage applications.