3D hierarchical CoWO4/Co3O4 nanowire arrays for asymmetric supercapacitors with high energy density

Abstract

A 3D hierarchical CoWO4/Co3O4 structure, with the synergetic effect of diverse materials, large specific surface area and fast transmission of electrons and ions is synthesized by a facile and efficient microwave hydrothermal method. We found that CoWO4 and 3D CoWO4/Co3O4 exhibit four pairs of redox peaks, which were discussed systematically. The hybrid electrode shows excellent specific capacitance of 1728 F g−1 at current density of 2.7 mA cm−2 (1 A g−1) with superior rate capability and satisfactory cycling stability (85.9% capacitance preserved after 5000 cycles). The asymmetric supercapacitors assembled with CoWO4/Co3O4 and activated carbon exhibit high energy density (57.8 Wh kg−1) and power density (6000 W kg−1 at 40.64 Wh kg−1), with remarkable cycle life. The above results indicate that the ordered CoWO4/Co3O4 nanowire arrays synthesized by this approach would be a promising candidate for practical application of high-performance supercapacitors.