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Constructing hierarchical core‐shell configuration from well‐known metal sulfides is one way to further tune and utilize unique species. Herein, a novel core‐shell structure is developed based on CoS deposited on NiS nanosheets, which involves hydrothermal and electrodeposition method. The micromorphology of the composite electrode can be optimized by adjusting the cycles of electrodeposition. Taking advantages of the highly conductive, open framework of the core‐shell nanolayer, the 5‐NiS@CoS electrode shows a specific capacitance of 1210 F g−1 at a current density of 1 A g−1 (retaining 82% from 1 to 10 A g−1, while NiS substrate is only 39%). The specific capacitance retention rate is 80.94% at 10 A g−1 after 2000 cycles (NiS substrate is 59.6%). Moreover, NiS@CoS//AC asymmetric supercapacitor device delivers an energy density of 24.1 Wh kg−1 at a power density of 752.15 W kg−1 and remarkable stability (over 80% retention after 5000 cycles). This work may prompt the exploration of the synthesis of inexpensive compounds incorporating highly reactive components for supercapacitors.

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Transition-metal phosphates/phosphides, as an emerging kind of prominent electroactive material, have drawn extensive attention in the fields of energy conversion and storage owing to their high electrical conductivity and metal-like properties. Herein, we report the preparation of hierarchical Ni–Co–P/PO x /C nanosheets in a controllable manner using nickel–cobalt metal–organic framework (NiCo-MOF) as the precursor, followed by a low-temperature phosphating method. Electrochemical studies show that the Ni–Co–P/PO x /C nanosheets exhibit good reversible capacity and excellent rate capability and possess capacities of 583 and 365.7 C g–1 at 1 and 30 A g–1, respectively. Furthermore, a two-electrode device assembled by Ni–Co–P/PO x /C and reduced graphene oxide shows a peak energy density of 37.59 Wh kg–1 at a power density of 800 W kg–1 and a stable capacitive performance. These results indicate that the obtained bimetallic Ni–Co–P/C is a promising anode material for capacitive energy storage devices.

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