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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Architectural Nanomembranes as Cathode Materials for Li-O2 Batteries

Lu, Xueyi 31 August 2017 (has links) (PDF)
Li-O2 batteries have attracted world-wide research interest as an appealing candidate for future energy supplies because they possess the highest energy density of any battery technology. However, such system still face some challenges for the practical application. One of the key issues is exploring highly efficient cathode materials for Li-O2 batteries. Here, a rolled-up technology associated with other physical or chemical methods are applied to prepare architectural nanomembranes for the cathode materials in Li-O2 batteries. The strain-release technology has recently proven to be an efficient approach on the micro/nanoscale to fabricate composite nanomembranes with controlled thickness, versatile chemical composition and stacking sequence. This dissertation first focuses on the synthesis of trilayered Pd/MnOx/Pd nanomembranes. The incorporation of active Pd layers on both sides of the poor conductive MnOx layer commonly used in energy storage systems greatly enhances the conductivity and catalytic activity. Encouraged by this design, Pd nanoparticles functionalized MnOx-GeOy nanomembranes are also fabricated, which not only improve the conductivity but also facilitate the transport of Li+ and oxygen-containing species, thus greatly enhancing the performance of Li-O2 batteries. Similarly, Au and Pd arrays decorated MnOx nanomembranes act as bifunctional catalysts for both oxygen reduction reaction and oxygen evolution reaction in Li-O2 batteries. Moreover, by introducing hierarchical pores on the nanomembranes, the performance of Li-O2 batteries is further promoted by porous Pd/NiO nanomembranes. The macropores created by standard photolithography facilitate the rolling process and the nanopores in the nanomembranes induced by a novel template-free method supply fast channels for the reactants diffusion. In addition, a facile thermal treatment method is developed to fabricate Ag/NiO-Fe2O3/Ag hybrid nanomembranes as carbon-free cathode materials in Li-O2 batteries. A competing scheme between the intrinsic strain built in the oxide nanomembranes and an external driving force provided by the metal nanoparticles is introduced to tune the morphology of the 3D tubular architectures which greatly improve the performance by providing continuous tunnels for O2 and electrolyte diffusion and mitigating the side reactions produced by carbonaceous materials.
2

Architectural Nanomembranes as Cathode Materials for Li-O2 Batteries

Lu, Xueyi 17 August 2017 (has links)
Li-O2 batteries have attracted world-wide research interest as an appealing candidate for future energy supplies because they possess the highest energy density of any battery technology. However, such system still face some challenges for the practical application. One of the key issues is exploring highly efficient cathode materials for Li-O2 batteries. Here, a rolled-up technology associated with other physical or chemical methods are applied to prepare architectural nanomembranes for the cathode materials in Li-O2 batteries. The strain-release technology has recently proven to be an efficient approach on the micro/nanoscale to fabricate composite nanomembranes with controlled thickness, versatile chemical composition and stacking sequence. This dissertation first focuses on the synthesis of trilayered Pd/MnOx/Pd nanomembranes. The incorporation of active Pd layers on both sides of the poor conductive MnOx layer commonly used in energy storage systems greatly enhances the conductivity and catalytic activity. Encouraged by this design, Pd nanoparticles functionalized MnOx-GeOy nanomembranes are also fabricated, which not only improve the conductivity but also facilitate the transport of Li+ and oxygen-containing species, thus greatly enhancing the performance of Li-O2 batteries. Similarly, Au and Pd arrays decorated MnOx nanomembranes act as bifunctional catalysts for both oxygen reduction reaction and oxygen evolution reaction in Li-O2 batteries. Moreover, by introducing hierarchical pores on the nanomembranes, the performance of Li-O2 batteries is further promoted by porous Pd/NiO nanomembranes. The macropores created by standard photolithography facilitate the rolling process and the nanopores in the nanomembranes induced by a novel template-free method supply fast channels for the reactants diffusion. In addition, a facile thermal treatment method is developed to fabricate Ag/NiO-Fe2O3/Ag hybrid nanomembranes as carbon-free cathode materials in Li-O2 batteries. A competing scheme between the intrinsic strain built in the oxide nanomembranes and an external driving force provided by the metal nanoparticles is introduced to tune the morphology of the 3D tubular architectures which greatly improve the performance by providing continuous tunnels for O2 and electrolyte diffusion and mitigating the side reactions produced by carbonaceous materials.

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