Hydrothermally synthesized FeCo2O4 nanostructures: Structural manipulation for high-performance all solid-state supercapacitors

The exploration of high performance supercapacitors has received emerging the worldwide research interests in satisfying the gradually increased energy consumption. In this paper, we adopt a facile hydrothermal strategy to synthesize ternary FeCo2O4 directly on nickel foam. A series of structure such as nanowires, nanoflake@nanowire hetero-structure and hierarchical nanospheres have been achieved via modulating the synthetic time. The morphology and structure of the as-prepared samples are characterized by using scanning electron microscopy and X-ray diffraction spectroscopy. The relationship between the detail processing parameters and electrochemical performance are also revealed by cyclic voltammetry, galvanostatic charge-discharge measurements, cycle stability tests and electrochemical impedance spectroscopy. Notably, the as-prepared nanoflake@nanowire hetero-structure exhibits a high specific capacitance of about 969 F g(-1) at 2 A g(-1) in alkaline aqueous solution and a remarkable cycling stability (91% capacity retention after 2000 cycles). The excellent supercapacitors performance of nanoflake@nanowire hetero-structure can be attributed to the high conductivity, large active area as well as robust architectures that derive from structural synergetic effects. Furthermore, a symmetric all solid-state supercapacitor has been fabricated by using nanofiake@nanowire hetero-structure as both the anode and cathode electrodes. The as-fabricated supercapacitor delivers excellent electrochemical performance. It's anticipated that FeCo2O4 would be a promising material for electrochemical energy storage applications.