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Nanostructured Carbon-Based Composites for Energy Storage and Thermoelectric Applications

Hsieh, Yu-Yun
http://rave.ohiolink.edu/etdc/view?acc_num=ucin157322525150617

Abstract Details

2019, PhD, University of Cincinnati, Engineering and Applied Science: Materials Science.
Carbon-based materials have been proposed as current collectors (conductive scaffold) to improve the electrical conductivity of active materials for energy storage devices, such as lithium ion batteries (LIB) or lithium-sulfur (Li-S) batteries, or as a coating layer of the separator to restrain the shuttling effect of Li-polysulfides (LiPS). However, previously reported Li-S batteries lack a good adhesion between the cathode and the separator, thus calling for further research on design and materials selection to achieve the optimal battery performance. Also, few of them have successfully integrated sp2 hybridized carbon and sp3-reach carbon into one monolithic structure: in a way that sp2 carbon is responsible for electron transfer and sp3 carbon is capable of a high loading of active materials. In order to overcome these limitations, here we report two novel nanocarbon current collectors for energy storage devices. One of them is a free-standing oxygen plasma functionalized, three-dimensional graphene (O3DG). Both the 3D graphene (3DG) and the used polypropylene (PP) separator have been functionalized in order to achieve high hydrophilicity (wettability), high accessibility towards the ionic electrolyte, and good adhesion between O3DG and OPP separator. In addition, the oxygen functional groups help to inhibit the migration of lithium polysulfide (LiPS). The O3DG-sulfur (O3DG-S) combined with an oxygen functionalized polypropylene (OPP) separator resulted in a composite structure, which was introduced for the first-time a Tri-Functional Structure (TFS) for Li-S battery. The composite consisted of a current collector, cathode material and included a part of the separator. This work also addressed some issues with Li metal anode of Li-S battery such as uncontrollable Li deposition, growth of Li dendrites and significant volume changes during the cycling process. Using O3DG integrated with Li metal (Li-O3DG) worked as a stable scaffold material for Li plating and stripping. The oxygen functional groups attached on the 3DG were proven to serve as lithiophilic sites for uniform lithium nucleation. The created O3DG carbon scaffold is resilient towards serious volumetric change during cycles. In addition, the 3D porous structure can reduce the effective local current density. The other current collector introduced in this dissertation is an in-situ grown network of a nitrogen-doped carbon nanotube (NCNT) on a three-dimensional (3D) graphene. The proposed structure (NCNT-3DG) is a bio-inspired nanomaterial with a design of a “natural forest”. The in-situ growth of NCNT on 3D graphene guarantees a fast electron transfer between NCNT and 3DG. The hydrophilic nature of NCNTs insures a high loading of the active materials such as Li4Ti5O12 (LTO). A spin-off thermoelectric project was also included and described in this work as an additional effort that benefited from the materials development related to the battery research. Herein, we present the synthesis and thermoelectric (TE) properties of free-standing, 3DG-polyaniline (PANI) composites. This material provided an excellent electrical conductivity and a reasonable Seebeck coefficient along with very good mechanical integrity preserved when bending, thus making it a promising candidate for flexible TE.
Vesselin Shanov, Ph.D. (Committee Chair)
Gregory Beaucage, Ph.D. (Committee Member)
Jude Iroh, Ph.D. (Committee Member)
Jingjie Wu, Ph.D. (Committee Member)
125 p.
Materials Science
Porous nanocarbon current collector; Lithium-sulfur battery; Polysulfide shuttling effect; Nitrogen doping; Oxygen plasma functionalization; Flexible hybrid thermoelectric nanocomposite

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Citations

  • Hsieh, Y.-Y. (2019). Nanostructured Carbon-Based Composites for Energy Storage and Thermoelectric Applications [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin157322525150617

    APA Style (7th edition)

  • Hsieh, Yu-Yun. Nanostructured Carbon-Based Composites for Energy Storage and Thermoelectric Applications. 2019. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin157322525150617.

    MLA Style (8th edition)

  • Hsieh, Yu-Yun. "Nanostructured Carbon-Based Composites for Energy Storage and Thermoelectric Applications." Doctoral dissertation, University of Cincinnati, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin157322525150617

    Chicago Manual of Style (17th edition)

ucin157322525150617
87
© 2019, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.