Hierarchical 3D NiCo2O4@ZnWO4 core-shell structures as binder-free electrodes for all-solid-state supercapacitors

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Developing supercapacitors with high energy density, good rate capability, and superior cycle life is crucial to the ever-increasing energy storage devices. However, how to develop novel electrodes materials and build a new type of nanostructures with large surface area, low resistance, and stable microstructures is still a challenge work. Fortunately, there is an effective strategy by designing the rational core-shell nanostructures as binder-free electrode materials to improve the electrochemical performance of supercapacitors. Herein, we have successfully realized a high-energy-density, good-rate-capability and long-life all-solid-state symmetric supercapacitor (SSC) by developing the hierarchical 3D NiCo2O4@ZnWO4 core-shell structures for the first time. The free-standing SSC based on the nanosheet arrays core-shell structures gives rise to a high areal capacitance of 288.4 mF cm−2 at a current density of 4 mA cm−2 and 248.9 mF cm−2 even at a current density of 40 mA cm−2, a high energy density of 28.46 W h kg−1 at 0.79 kW kg−1, and ∼97.5% of the capacitance can be retained after 5000 cycles of charge-discharge. The remarkable electrochemical behaviors demonstrate that the nickel foam supported NiCo2O4@ZnWO4 nanosheet arrays electrodes are highly desirable for application as high-performance electrochemical energy storage devices.