Date of Award

5-2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Committee Chair/Advisor

Dr. Apparao M. Rao

Committee Member

Dr. Stephen E. Creager

Committee Member

Dr. Ramakrishna Podila

Committee Member

Dr. Shiou-Jyh Hwu

Abstract

This dissertation describes my research on surfactant-free synthesis of nanomaterials with applications for alcohol fuel-cell electrodes, and design and fabrication of nanomaterials-based current collectors that improve the performance of lithium-ion batteries (LIBs) by replacing existing current collectors.

Chapter 1 provides a background on the electroanalytical tools used in this research, and an introduction to fuel cells and LIBs.

Chapter 2 describes a novel synthesis method for fabricating gold-graphene composites by laser ablation of a gold strip in water. A well-known limitation in the fabrication of a metal-graphene composite is the use of surfactants that strongly adsorb on the metal surface and consequently reduce the catalytic activity of the metal catalyst. I developed a laser ablation-based one-pot synthesis to decorate graphene with gold nanoparticles (AuNPs) in water without using any surfactants. This linker-free gold-graphene composite was successfully tested as an electrode for the electrocatalytic oxidation of alcohols.

A novel electrochemical method for depositing a porous gold-polycurcumin (Au-Polycurcumin) nanocomposite on conducting surfaces is presented in chapter 3. Au-Polycurcumin showed an excellent electrocatalytic activity for oxidation of small organic molecules such as ethanol, and methanol.

In chapter 4, I demonstrate that reducing the resistance at the current collector active material interface (CCAMI) is a key factor for enhancing the performance of LIBs. I show that carbon nanotubes (CNTs), either directly grown or spray-coated on Al foils, are highly effective in reducing the CCAMI resistance of traditional LIB cathode materials (LiFePO4 or LFP, and LiNi0.33Co0.33Mn0.33O2 or NMC). The vertically aligned CNT-coated electrodes exhibited energy densities as high as (1) ∼500 W h kg–1 at ∼170 W kg–1 for LFP and (2) ∼760 W h kg–1 at ∼570 W kg–1 for NMC, both with a Li metal anode.

In chapter 5, I demonstrate a surfactant-free spray coating process to coat commercial cellulose-based paper with CNTs. The prepared paper-CNTs are capable of replacing the conventional aluminum foil used in LIBs. Paper-CNTs were coated with LiFePO4 as the active material and used as cathodes with Li as the anode, and the assembled LIBs showed a high energy density of 460 Wh kg-1 at a power density of 250 W kg-1.

Included in

Chemistry Commons

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