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Hollow Nanostructured Anodes Of Silicon And Metal Oxides For Lithium-lon Batteries:Synthesis,Characterization,and Application

Posted on:2014-02-03Degree:MasterType:Thesis
Country:ChinaCandidate:J LiuFull Text:PDF
GTID:2231330398454476Subject:Materials engineering
Abstract/Summary:PDF Full Text Request
New anode materials for lithium-ion batteries with long cycle life and high capacity are urgently needed to meet the increasing demands of portable electronic device and electric vehicles (or hybrid electric vehicles). Owing to their unique structural properties, hollow nanostructured anodes are expected to exhibit improved cyclic performance, higher capacity, and rate capability, and thus have been considered as one of the promising alternatives for lithium-ion batteries with long cycle life, high energy density, and power density.In the dissertation, we have developed a novel approach with water-soluble Na2SiF6nanomaterials as temtlates to synthesize hollow nanostructures (e.g., Si and CoO) serving as high-performance anode of lithium-ion batteries. We have also developed a simple coating method to produce yolk-shell nanostructures (e.g., Si@C yolk-shell and Fe2O3@C yolk-shell) in high-yield for anodes of lithium-ion batteries with high-performance. Owning to the unique structural property, the afore-mentioned hollow nanostructured anodes exhibited improved electrochemical performance. The main innovative results are listed as follows:(1) With polyacrylic acid (PAA) as soft-templates, the morphology of nanostructures was tunned by controlling the concentration of PAA. In this synthesis, the Na2SiF6nanotubes and nanospindles were successfully generated.(2) With water-soluble Na2SiF6nanospindles as templates, the Si hollow nanospindles were prouced through RF-sputtering deposition. Compared to the Si film, the Si hollow nanospindles exhibited higher capacity and improved cyclic performance for anodes of lithium-ion batteries. In addition, the CoO hollow nanospindles were also produced by using the similar approach. Serving as anodes of lithium-ion batteries, the CoO hollow nanospindles exhibited improved cyclic performance and higher capacity.(3) The Si@C yolk-shell nanostructures were successfully produced by a simple coating method with Si nanoparticles as the cores. This synthesis involved the coating of a SiO2layer by a Stober approach, the coating of a carbon layer through a hydrothermal carbonization approach, and then the removal of SiO2in a sequence on the surface of the Si nanoparticles. The Si@C yolk-shell nanostructures exhibited the improved cyclic performance and higher capacitiy for amodes of lithium-ions battereis. The Fe2O3@C yolk-shell nanostructures were also produced by using the similar approach. In addition, the Fe23@C yolk-shell nanostructures exhibited higher capacitiy and improved cyclic performance for anodes of lithium-ions batteries.
Keywords/Search Tags:Lithium-Ion Batteries, Anode, Hollow Nanostructures, Water-SolubleTemplate, Silicon-Based Materials, Transition Metal Oxide
PDF Full Text Request
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