자료유형  

 학위논문

Control Number  

0017162767

International Standard Book Number  

9798382738369

Dewey Decimal Classification Number  

541

Main Entry-Personal Name  

Wang, Guangyu.

Publication, Distribution, etc. (Imprint  

[S.l.] : University of Michigan., 2024

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Physical Description  

223 p.

General Note  

Source: Dissertations Abstracts International, Volume: 85-12, Section: B.

General Note  

Advisor: Kieffer, John.

Dissertation Note  

Thesis (Ph.D.)--University of Michigan, 2024.

Summary, Etc.  

요약The transition from liquid to solid-state electrolytes (SSEs) for battery applications offers advantages such as higher energy density, enhanced safety, improved stability, and a solution to the dendrite growth issue during charging. Single-ion conduction is pursued to enhance charge carrier mobility and mitigate electrode degradation. In this thesis, we explore two material systems: polymer-matrix composites and organic-inorganic silica hybrid materials, with the aim of understanding ion transport mechanisms and optimizing material design for improved performance.In the poly(ethylene) oxide (PEO)-based composite, an interfacial region develops surrounding amorphous Li1.3Al0.3Ti1.7(PO4)3 (LATP) nanoparticles, exhibiting 30 times higher Li+ mobility compared to the polymer matrix. We achieve uniform nanoparticle dispersion through a water-based in-situ precipitation method, leading to a 20°C conductivity of 3.8x10-4 S·cm-1 at a particle loading of 12.5 vol% and a Li+ concentration of 1.65 nm-1. Comparative infrared spectroscopy reveals increased disorder in the interphase polymer, offering low activation barrier cation migration pathways. Analysis using a transition state theory-based approach to examine the temperature dependence of ionic conductivity reveals that thermally activated processes within the interphase benefit more from higher activation entropy than from a decrease in activation enthalpy. Although lithium infusion from LATP particles is modest, charge carriers tend to concentrate in a space-charge configuration near the particle/polymer interface.To improve Li+ transference numbers, electrochemical stability, and mechanical strength, a hybrid design is pursued, consisting of a nano-porous silica backbone bi-functionalized with the cation donor 2-[(Trifluoromethanesulfonylimido)-N-4-sulfonylphenyl] ethyl (TFSISPE) anion and the molecular brush 2-[Methoxy(polyethyleneoxy)6-9propyl] trimethoxysilane (oligo-PEG). A lowdensity nano-porous structure is created using sol-gel synthesis. The backbone functionalization is achieved through a carefully timed and phased introduction of pre-hydrolyzed TFSISPE anion and oligo-PEG to the partially gelled silica. As a result, cation donor groups are covalently bonded to the backbone. Subsequently, low-molecular-weight polyethylene oxide replaces the solvent in the nanopores. Oligo-PEG grafting increases the pore fill factor and significantly boosts ionic conductivity (5.2x10-4 S cm-1 at 20°C for a one-molar Li+ concentration) by reducing conductivity osmotic drag resulting from entanglement between oligo-PEG and PEO. Anchoring the TFSISPE anion to the backbone yields a Li+ transference number tLi+∼0.91.Incorporating liquid carbonates into the porous silica backbone, e.g., propylene carbonate (PC) and ethylene carbonate (EC), further enhances the conductivity of the hybrid material to 2.9x10-3 S·cm-1 at 20°C, with a Li+ transference number of 0.9 for electrolytes with oligo-PEG grafting. However, liquid carbonates have poor thermal stability, even when confined to nanopores. The ionic liquid 1- Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM TFSI) proves to be the best pore medium for these hybrids. It has superior thermal stability, up to 275°C, thus potentially suitable for practical applications. It reaches ionic conductivities of nearly 10-2 S·cm-1, but at the cost of a lower transference number (0.435) due to the binary salt nature of the ionic liquid. Cation mobility in these systems exhibits a maximum as a function of the average pore size, which is controlled by varying the water-to-TEOS ratio (Rw ratio) during the backbone synthesis. Here we provide a cumulative account of systematic materials design efforts. The sequential implementation of these elements allows us to discern their individual importance of the various materials design elements and assess their collective influence on the performance characteristics of the materials.

Subject Added Entry-Topical Term  

Physical chemistry.

Subject Added Entry-Topical Term  

Materials science.

Subject Added Entry-Topical Term  

Polymer chemistry.

Subject Added Entry-Topical Term  

Organic chemistry.

Index Term-Uncontrolled  

Lithium-ion batteries

Index Term-Uncontrolled  

Electrolytes

Index Term-Uncontrolled  

Organic-inorganic hybrids

Index Term-Uncontrolled  

Ion mobility

Index Term-Uncontrolled  

Interphase polymer

Added Entry-Corporate Name  

University of Michigan Materials Science and Engineering

Host Item Entry  

Dissertations Abstracts International. 85-12B.

Electronic Location and Access  

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Control Number  

joongbu:658644