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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Functionalized carbon nanomaterials are potential candidates as anode materials in potassium-ion batteries (PIBs). The inevitable defect sites in architectures greatly affect the physicochemical properties of carbon nanomaterials, thus defect engineering...

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Design and fabrication of novel electrode materials with excellent specific capacitance and cycle stability are urgent for advanced energy storage devices, and the combinability of multiple modification methods is still insufficient. Herein, Ni 2+ , Zn 2+ double-cation-substitution Co carbonate hydroxide (NiZnCo-CH) nanosheets arrays were established on 3D copper with controllable morphology (3DCu@NiZnCo-CH). The selfstanding scalable dendritic copper offers a large surface area and promotes fast electron transport. The 3DCu@NiZnCo-CH electrode shows a markedly improved electrochemical performance with a high specific capacity of ∼1008 C g −1 at 1 A g −1 (3.2, 2.83, and 1.26 times larger than Co-CH, ZnCo-CH, and NiCo-CH, respectively) and outstanding rate capability (828.8 C g −1 at 20 A g −1 ) due to its compositional and structural advantages. Density functional theory (DFT) calculation results illustrate that cation doping adjusts the adsorption process and optimizes the charge transfer kinetics. Moreover, an aqueous hybrid supercapacitor based on 3DCu@NiZnCo-CH and rGO demonstrates a high energy density of 42.29 Wh kg −1 at a power density of 376.37 W kg −1 , along with superior cycling performance (retained 86.7% of the initial specific capacitance after 10,000 cycles). Impressively, these optimized 3DCu@NiZnCo-CH//rGO devices with ionic liquid can be operated stably in a large potential range of 4 V with greatly enhanced energy density and power capability (110.12 Wh kg −1 at a power density of 71.69 W kg −1 ). These findings may shed some light on the rational design of transition-metal compounds with tunable architectures by multiple modification methods for efficient energy storage.

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