Synthesis of self-templated urchin-like Ni2Co(CO3)2(OH)2 hollow microspheres for high-performance hybrid supercapacitor electrodes

Abstract Developing novel nanostructures is always the most decisive aspect for high-performance supercapacitor electrodes. Thus, a facile one-step and self-templated method is successfully developed for the fabrication of urchin-like Ni2Co(CO3)2(OH)2 hollow microspheres (NiCoHSs) as a high-performance hybrid supercapacitor electrodes. The synthesis conditions are carefully adjusted and the mechanisms of morphology transformation are clearly illustrated. The favorable morphology with a large specific surface area, suitable pore sizes, and good conductivity endows a high specific capacity (890.8 C g−1 at 0.5 A g−1) and excellent rate retention (700.8 C g−1 at 50 A g−1), and high stability (87.5% over 5000 cycles), which outperforms most reported electrodes based on nickel-cobalt oxides/hydroxides. Contributed by the uniquely engineered electrodes, a high-performance hybrid supercapacitor (HCS) is assembled, which exhibited a high specific capacity of 256.9 C g−1 (160.5 F g−1) at 0.5 A g−1 with an operating voltage of 1.6 V and an outstanding energy density of 57.1 W h kg−1 at a power density of 400.0 W kg−1. This work offers a facile self-templated method to fabricate bimetal Transition-metal oxides (TMOs) electrodes for hybrid supercapacitors.