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

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 (6000Wkg(-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.