Nickel cobalt sulfide coated iron nickel selenide hierarchical nanosheet arrays toward high-performance...

Tailoring the electronic structure of nanomaterials by constructing core-shell heterostruture is a compelling strategy to design novel electrode materials with modified physiochemical properties for supercapacitors with improved performance. Herein, for the first time, we in situ fabricate iron nickel selenide (FeNiSe₂)@nickel cobalt sulfide (Ni_4.5Co_4.5S₈) core-shell nanosheet arrays on carbon cloth by an electrodeposition approach and a selenization treatment. This three-dimensional hierarchcial porous framework formed by plentiful interconnected nanosheets can expose numerous redox active sites with varied oxidation states and provide a conductive and porous skeleton for rapid ion/electrolyte ions transport. Benefiting from its modulated electronic structure and synergetic effect of metal-like FeNiSe₂ and Ni_4.5Co_4.5S₈, the as-synthesized FeNiSe₂@Ni_4.5Co_4.5S₈ electrode displays a large specific capacity of 236.9 mAh g^-1 at 1 A g^-1, remarkable rate capability with 80.6% capacity retention at 20 A g^-1, and stable cyclic performance, which are superior to those of pure FeNiSe₂ and Ni_4.5Co_4.5S₈ electrodes. Besides, the assembled FeNiSe₂@Ni_4.5Co_4.5S₈//porous carbon hybrid supercapacitor device offers an energy density of 69.0 Wh kg^-1 at 799.2 W kg^-1, and exceptional cycling stability with 91.2% capacity retention after 10,000 cycles. This work offers a synthetic strategy to explore core-shell electrode materials with tunable architecture and morphology for high-performance energy storage devices.