Hierarchical NiCo2O4@Ni(OH)2 core-shell nanoarrays as advanced electrodes for asymmetric supercapacitors with high energy density

Abstract

Development of high-performance supercapacitors with high energy density is urgently required for energy storage device but remains challenging. In this work, novel NiCo2O4@Ni(OH)2 (denoted as NCO-NH) core-shell nanoarrays were synthesized. Benefiting from the structural and compositional advantages, the NCO-NH core-shell nanoarrays exhibited high specific capacitances (2218.0 and 1796.0 F g−1 at current densities of 1 and 10 A g−1, respectively) and outstanding cycling stability (96.4% retention of the initial specific capacitance at 10 A g−1 after 5000 cycles). Using such NCO-NH nanoarrays as cathode and activated carbon as anode, an asymmetric supercapacitor (ASC) is further fabricated. This ASC device achieves a high energy density of 98.5 W h kg−1 at a power density of 800 W kg−1 (at current densities of 1 A g−1) and an energy density of 61.5 W h kg−1 at a high power density of 8000 W kg−1 (at current densities of 10 A g−1). This work highlights that construction of core-shell nanoarrays by coupling of bimetallic oxide with hydroxide could be a feasible way to obtain advanced electrode materials for high-performance supercapacitors.