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The Research On The Synthesis Of Core-shell Structural Metal Oxide Nanoarray And Their Electrochemical Performance

Posted on:2017-10-14Degree:MasterType:Thesis
Country:ChinaCandidate:W J RenFull Text:PDF
GTID:2311330488969420Subject:Physics
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In recent years, while many efforts have been made to solve the increasing problems of areas such as energy and environment, higher demands are required in the energy of mobile electronic equipment. Metal oxide nanomaterials, the electrochemical energy storage materials, with the advantages of high capacity, low cost and good stability, are becoming the alternative carbon material used for electrode materials in future. The electrochemical properties of metal oxide nanomaterials depend largely on their own morphology and structure, so synthesis of nanomaterials of uniform morphology and stable structure can largely improve the performances and applications. In this paper, through controlling morphology structure and applies of multiple metal oxide composite material, we synthetized different kinds of core-shell structure metal oxide nanoarray by simple hydrothermal and electrochemical deposition methods, and studied their performances of lithium ion batteries and supercapacitors. Our research work is mainly as following aspects:In chapter 2, NiMoO4@Co?OH?2 core-shell structure nanoarrays ?CSNAs? supported on Ni foam were successfully fabricated via facile hydrothermal growth and electrochemical deposition route, applied in supercapacitors ?SCs?. The smart combination of Co?OH?2 and NiMoO4 in nanarrays shows greatly enhanced electrochemical performance. The Co?OH?2 nanoflakes wrapped on the surface of each NiMoO4 nanowire uniformly, which could increase the capacitance of NiMoO4 nanowire arrays ?NWAs? to a high areal capacitance of 2.335 F cm-2 at 5 mA cm-2 and 0.909 F cm-2 at 50 mA cm'2, respectively. The electrode also exhibited good cycling ability,83% of the initial capacity remained after 5000 cycles at a current density of 20 mA cm-2. These results indicate that the NiMoO4@Co?OH?2 CSNAs could be a promising electrode material for high-performance electrochemical capacitors.In chapter 3, Mn0.10Co0.09O@NiO core-shell structure nanoarrays ?CSNAs? supported on nickel foams were successfully fabricated via two facile hydrothermal growth routes and they were investigated for lithium-ion batteries ?LIBs? measurements. The combination of NiO nanoflakes in Mn0.10Co0.90O nanowire arrays showed greatly enhanced electrochemical performance. The NiO nanoflakes wrapped on the surface of Mn0.10Co0.90O nanowire uniformly, improving the capacitance of Mn0.10Co0.90O@NiO CSNAs. The excellent features allow the Mn0.10Co0.90O@NiO CSNAs to be used as lithium-ion battery electrode, with high capacity 729.13 mA h g-1 after 100 cycles at a current density of 200 mA h g-1, as well as a very good ratecapability and coulombic efficiencies, indicating the potential application of Mn0.10Co0.90O@NiO CSNAs for high performance lithium-ion batteries devices.In chapter 4, Mn0.10Co0.90O@NiO core-shell structure nanoarrays ?CSNAs? supported on nickel foams were also investigated for supercapacitors ?SCs? electrode material. The capacitance of Mn0.10Co0.90O@NiO CSNAs electrode reached 1801.84 F g-1 in the first cycle and it gradually decreased to 1160.8 F g-1 after 3000 cycles, resulting in an overall capacitance loss of about 35%, at a current density of 9 A g-1. And the corresponding coulombic efficiencies most of cycles were over 99% obtained from the first cycles to 3000 cycles at a current density of 9 A g"1 during the discharge/charge processes. The Mn0.10Co0.90O@NiO CSNAs electrode displays higher capacitance performance than the Mn0.10Co0.90O NWAs electrode.
Keywords/Search Tags:Metal oxide, Nanomaterials, Core-shell structure, Electrochemical property, Supercapacitor, Lithium-ion batteries
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