| As ideal pseudocapacitive electrode materials,transition metal hydroxides and sulfides have great potential in the application of hybrid supercapacitor cathode materials.In addition,nanomaterials with a hierarchical structure have unique advantages in the field of electrochemical energy storage.The hierarchical structure can not only greatly enlarge the specific surface area of the electrode material,but also effectively ensure better electrolyte infiltration,which is particularly important for improving the utilization rate of the active materials.In this paper,the in-situ grown sulfide improves the conductivity of the electrode and promotes the efficient transmission of electrons.Simultaneously,the hierarchical structure composed of one-dimensional and two-dimensional nanomaterials integrates the advantages of each component and exposes more active sites.These measures can ensure the full utilization of effective electrode materials,thus realizing the improvement of electrochemical performance.The main research contents of this paper are as follows:(1)We construct Co1-x-yNixZny(CO3)0.5(OH)·0.11H2O nanoneedles-Ni Co layered double hydroxide(Ni Co-LDH)nanosheets hierarchical architecture on vulcanized Ni foam(Ni3S2-NF)based on multi-step reaction route.The internal Ni3S2-NF matrix not only greatly boosts charge transfer,but also is employed to load the active materials.The Co1-x-yNixZny(CO3)0.5(OH)·0.11H2O nanoneedles-Ni Co-LDH nanosheets hierarchical architecture presents an open and orderly structure,which could both enable rich contact sites and integrate the merits of every component,thus generating a synergistic electrochemical enhancement.As expected,the hierarchical architecture electrode is served as supercapacitive positive material,which displays high rate capacities(763.2 C g-1 at 1 A g-1 and 598 C g-1 at 20 A g-1)and long-term cyclic duration(retaining 88.71%capacity after 7000 cycles at 10 A g-1).Additionally,a hybrid supercapacitor(HSC)based on such positive material is assembled,which also exhibits an energy density of 42.8 Wh kg-1(at 800 W kg-1)and outstanding cyclic stability(retaining 80%capacity after 10000cycles at 5 A g-1).Remarkably,a blue LED can be triggered by two series-connection HSCs for more than 24 minutes,making it have a broad application prospect in energy storage.(2)Ultra-thin Ni(OH)2 nanosheets are directly grow on the surface of Ni3S2 nanorod arrays supported on nickel foam through a two-step hydrothermal method to form Ni3S2/Ni(OH)2 hierarchical nanoarrays.The Ni3S2 nanorod arrays synthesized on nickel foam(NF)using hydrogen peroxide(H2O2)as an inducer can not only serve as the main channel for charge transport but also support the growth of active materials,moreover,the exposed active parts can also participate in the electrochemical energy storage process.The external ultra-thin Ni(OH)2 nanosheets increase the contact area with the electrolyte and enrich the electrochemical active sites.The reasonable construction of the Ni3S2/Ni(OH)2 hierarchical structure increases the effective specific surface area of the electrode and produces a synergistic effect between the components,thus exhibiting excellent electrochemical performance.The obtained Ni3S2/Ni(OH)2 electrode presents a high specific capacitance(826 C g-1 at 1 A g-1),relatively good rate performance(50%retention at 20 A g-1)and long-term cyclic duration(retaining 80%capacity after 3000cycles at 10 A g-1).In addition,our assembled Ni3S2/Ni(OH)2//AC hybrid supercapacitor(HSC)gives rise to a superior energy density of 48.3 Wh kg-1 at about 800 W kg-1,together with about 70%capacitance retention after 10000 cycles at 5 A g-1,further illustrating the possibility for practical application of the Ni3S2/Ni(OH)2 hierarchical structure electrode. |
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