Date of Award

5-25-2024

Publication Type

Thesis

Degree Name

M.A.Sc.

Department

Mechanical, Automotive, and Materials Engineering

Keywords

High Energy Ball Milling;High Energy Density;Li-ion Battery anode;Particle Pulverization;Silicon Anode;Wet Magnetic Millin

Supervisor

Reza Riahi

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

The demand for high energy density (HED) lithium-ion batteries (LIBs) by the electric vehicle (EV) and portable power electronics industry has led to the search for “next-gen” anode and cathode materials. The anode material in LIBs so far has primarily been fabricated with carbon-based material such as graphite. Of the proposed candidates, Silicon (Si) with a theoretical capacity of ~4200 mAh/g has emerged as a promising successor to improve LIB performance. However, the massive volume expansion of Si (~400%) due to silicide alloy formation during cell cycling has led to various remedies being researched to overcome this impediment. Of the remedies, nano-silicon (n-Si), in particular, has garnered significant attention and gained massive traction. Although promising n-Si utilization still undergoes volume expansion while its economic scalability is being withheld by its production cost due to the complex process involved. While the volume expansion of n-Si can be controlled by incorporating appropriate binders and various supporting structures, a decrease in its production cost is much desired. Particle pulverization (PP) via High Energy Ball Milling (HEBM) is a classical, cost effective, environmentally friendly and proven top-down approach for particle size reduction. This thesis introduces a new PP technique based on HEBM for synthesizing n-Si for Li-ion battery (LIB) application, utilizing readily available lab equipment. The setup for the technique involves the use of silicon nitride (Si3N4) milling media (milling balls), magnetic stir bars, magnetic stirrer and ethanol as milling medium to minimize oxidation. Since the technique is based on agitation from magnetic stirring and involves a wet milling medium, it is aptly named wet magnetic milling (WMM). The n-Si powder synthesized was used to prepare anode and test its performance in CR-2032 in coin cells. Scanning electron microscopy (SEM) was deployed to study the particle size and its morphology. Energy dispersive spectroscopy (EDS) was carried out to verify the chemical constituents of the n-Si powder synthesized. Surface profilometry was deployed to study the anode microstructure pre and post-cell cycling.

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