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 (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.