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| Under the condition of not using a binder, the active material can be directly grown on the conductive base material as the electrode of the capacitor. The internal space structure of this electrode material makes the ion transport area easy to diffuse and brings more active sites, which leads to its excellent electrical conductivity and the formation of a prominent conductive network. However, the adhesion between the active material and the substrate is weak and even easy to fall off, resulting in poor cycling performance of the capacitor To solve this problem, we provide a novel strategy. The Co-Ni double hydroxide core-shell structure was gradually formed by the pre-oxidation of copper foam, an interface-modulated copper foam framework surface, re-oxidation and electrodeposition. Furthermore，it was founded that the adhesive force of CuO grown free-standing on copper foam is enhanced in this way. The specific capacity of the prepared core-shell nanohybrid (POCF@CuO@CN LDH) by the two-step oxidation method was 4027.28 F g-1 at 1 A g-1, and that of the core-shell nanohybrid (OCF@CuO@CN LDH) prepared by the direct oxidation method was 2377.50 F g-1 at 1 A g-1. The former is 1.7 times than the latter. The POCF@CuO@CN LDH electrode has a capacitance retention rate of 80.84 % after 10000 cycles at 20 A g-1 with excellent multiplicity performance and long cycle stability. The as-assembled POCF@CuO@CN LDH//RGO asymmetric supercapacitor (ASC) provides a excellent energy density of 41.73 Wh kg-1 at a power density of 800.13 W kg-1 and a capacitance retention rate of 73.17 % after 10000 cycles at 5 A g-1. In addition, a commercial 1W light-emitting diode indicator with blue light can be energized for 4 minutes when two ultra-capacitor devices connected in series are linked in series. As such, it can be suggested that the two-step oxidation method, which provides a strategy for the integration of nanocomposite materials and substrates with strong interfacial adhesion, may have great potential in high-performance electrochemical devices. |
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| Keywords: Pre-oxidation; Interface; Core-shell structure; Robust adhesion; Supercapacitor |
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