Hierarchical layer-by-layer porous FeCo2S4@Ni(OH)2 arrays for all-solid-state asymmetric supercapacitors

Engineering multicomponent active materials as electrodes with a rationally structured design is an effective strategy to meet the high-performance requirements of supercapacitors. In this report we describe the fabrication of a hierarchical layer-by-layer porous FeCo2S4@Ni(OH)2 three-dimensional (3D) network on nickel foam, which shows both an excellent specific capacitance of 2984 F g−1 at 5 mA cm−2 and cycling stability over 5000 cycles. The outstanding performance is ascribed to the distinctive self-supported structure and the synergistic effect between FeCo2S4 and Ni(OH)2. Moreover, the all-solid-state FeCo2S4@Ni(OH)2//reduced graphene oxide asymmetric supercapacitor exhibits a high energy density of 64 W h kg−1 at a power density of 800 W kg−1 and excellent cycling stability (92.9% of capacity retention after 10 000 cycles), while the output voltage can reach 1.6 V. This rational design of the layer-by-layer structured electrode provides an innovative strategy for fabricating electrodes for future energy storage devices.