Facile synthesis of the 3D interconnecting petal-like NiCoO2/C composite as high-performance supercapacitor electrode materials

In the present work, a novel NiCoO2 nanoparticle/amorphous carbon composite was synthesized through an intercalation-calcination process under very mild reaction conditions (400 °C, without high vacuum). The NiCoO2/C composite possesses a unique 3D interconnecting petal-like architecture, together with appropriate compositing of NiCoO2 nanoparticles. The distinctive nanostructure endows a high specific capacitance of 190.4 mAh g−1 (equivalent conversion to 1713.7 F g−1) at the current density of 1 A g−1 (133.3 mAh g−1 at 20 A g−1) in a three-electrode system, using 3.0 M KOH as an aqueous electrolyte. And the remarkable cycling stability at a high current density of 10 A g−1 (∼2% loss over 3000 charge-discharge cycles) has also been demonstrated. Moreover, the fabricated asymmetric supercapacitor using the NiCoO2/C composite as the positive electrode material and activated carbon as the negative electrode material can deliver a relatively high energy density of 36.1 Wh kg−1 and a power density of 8000 W kg−1 under a high potential window of 0–1.6 V. The facile lattice orientation/confinement strategy described here is simple, of low cost, and eco-friendly, which makes the NiCoO2/C composite a promising electrode material for supercapacitors.