Core–Shell Nanostructured Hybrid of Nickel Hydroxide Supported on Copper Hydroxide Nanorod Arrays Used as Advanced Supercapacitors with High Efficiency and Ultraperformance

Abstract

continuously. Therefore, the exploration of new energy storage materials as well as the development of energy storage devices has become the core issues for the utilization and transformation of new energies. [1,2] It is well-known that supercapacitors, as a kind of nontoxic and environment-friendly apparatus for electricity storage and conversion in practical applications, have higher power density and longer cycling capacity, which overcome some drawbacks of traditional dielectric capacitors and chemical batteries. Unfortunately, much lower energy densities of supercapacitors have prevented their extensive applications in energy storage devices.At present, transition metal hydroxides, as a new type of pseudocapacitor materials, have been widely explored and further used in the fields of catalysis, electrochemistry, separation, and biotechnology. As a result, they have been attracting extensive attention from both the academic and industrial circles. Likewise, some inherent advantages of these transition metal hydroxides can be observed including superior redox activity, steerable chemical composition, diversiform physical morphology enormous, Langmuir surface area exposure, inherent high stability of atoms, and good anion exchange behavior. Therefore, the transition metal hydroxide has been broadly used for different electrode materials in the realm of supercapacitors. [3,4] Nevertheless, the electrochemical performance plus the practical application of supercapacitors prepared with transition metal hydroxides are usually hindered by their inherent low electrical conductivities from 10 −13 to 10 −17 S cm −1 . [5] Nickel hydroxide (Ni(OH) 2 ) is a classic transition-metal hydroxide applied in a variety of fields, which has been deemed to be an auspicious electrode on account of its remarkable specific capacitance, low cost, simple operation, and various physical morphologies. [6] However, it has been found that Ni(OH) 2 has poor electrical conductivity, which seriously hinders the transmission of electrons and slows down the redox reaction, resulting in poor rate capability. [7][8][9] Generally, one common strategy for tackling this problem is based on the combination of Ni(OH) 2 and conductive frameworks such as carbon materials, AC, graphene, and copperThe fascinating search for ultraefficient and high-powered supercapacitors has stimulated continuous exploration of diverse energy storage materials like transition metal hydroxides with core-shell structure. Thus in this paper, a novel core-shell hybrid electrode material of nickel hydroxide (Ni(OH) 2 ) supported on copper hydroxide nanorod arrays (Cu(OH) 2 NAs), which is constructed on copper foam as the substrate by an in situ chemical oxidation reaction accompanied by chemical bath deposition, is reported. As a result, it is found that the pre-fabricated Cu(OH) 2 @Ni(OH) 2 electrode has a remarkable areal capacitance of 9.27 F cm −2 and good cycling performance (retains 92.38% after 6000 cycles) compared to its counterpart Cu(OH) 2 nanorods (88.57%). Additio...

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