Controllable Synthesis of NiSe/MoSe2/MoO2 3D hierarchical hollow microspheres with enhanced performance for asymmetric supercapacitors

Abstract The application of hybrid materials with well−designed composition and morphology is an effective approach towards enhanced electrochemical performance of asymmetric supercapacitors (ASCs). Here a facile two−step growth−annealing strategy to construct a NiSe/MoSe2/MoO2 three−dimensional (3D) hierarchical hollow architecture comprising two−dimensional (2D) thin nanoflakes is reported. The reaction time and Ni/Mo mole ratio of precursor are crucial for the construction of NiSe/MoSe2/MoO2 3D hierarchical hollow microsphere (HHM). The as−synthesized NiSe/MoSe2/MoO2 3D HHM with large specific surface area and well−developed mesoporous can increase contact area between active material and electrolyte, and shorten the path and time for electrolyte ions transport, thereby achieving outstanding electrochemical performance. The NiSe/MoSe2/MoO2 3D HHM shows a high specific capacitance of 1061 F g−1 at a current density of 2 A g−1, exceptional rate capability (maintaining 57% of its initial capacitance at 20 A g−1) and stable long−term cycling performance (retaining 93.9% of its initial capacitance after 10000 cycles at 3 A g−1). Moreover, the NiSe/MoSe2/MoO2 3D HHM−based ASC provides a high energy density of 48.1 Wh kg−1 at a power density of 428 W kg−1, and still maintains 20.4 Wh kg−1 even at a high power density of 7.3 kW kg−1, suggesting its great potential in superior−performance ASCs.