Publication Date

2026

Document Type

Dissertation/Thesis

First Advisor

Ito, Yasuo

Degree Name

Ph.D. (Doctor of Philosophy)

Legacy Department

Department of Physics

Abstract

The importance of Li ion batteries as an energy storage device cannot be understated. The industry around energy storage has been steadily growing over the last few decades and continues to grow. However, the design of these devices has run into a bottleneck as both academics and industry specialists try to achieve even higher performance parameters, as well as trying to supplement critical materials such as Co, Li and Ni while maintaining cost and energy density. In particular, energy density, capacity retention, thermal and mechanical stability have become very important to improve. These critical parameters within the device are dominated by the battery cathode, which often accounts for more than half of cost of energy storage devices, thus detailed studies of cathode materials have been a focus of specialists all around the globe, enabling the energy storage industry to improve the production costs and supply security, alleviating some long-standing economic concerns. In particular, in the field of microscopy and microanalysis, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), electron backscatter diffraction (EBSD) have been extensively used to study these materials over the last few decades. In the recent years, however, transmission electron microscopy(TEM) has become considerably prevalent as the method of study for battery material structures due to its much greater spatial resolution, added spectroscopy methods that would be otherwise either difficult to execute or would not be local enough to allow nanoscale analysis and lastly the ability to analyze lighter elements local chemistry, which is something that most other analytical methods struggle with. In this study we will utilize TEM in order to isolate critical structure-based parameters for the electrochemical performance of battery cathode materials, analyze three methods of structure modification based on those parameters and introduce new solutions for the economical side of fabrication of those materials.

Several approaches of modifications of the structure and performance of battery cathode materials will be discussed, such as doping, secondary structure introduction and cathode-electrode layer modification. While these methods, especially doping have been extensively studied using various electrochemical study methods, in this study we would primarily focus on the effect of such approaches on the micro- and nano-structure of battery cathode materials. Lastly, as the conclusion of the study we will present an example of a few novel materials that have been developed as a result of such optimization studies.

Extent

226 pages

Language

en

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

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Text

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