Date of Award

8-16-2024

Document Type

Open Access Dissertation

Department

Chemical Engineering

First Advisor

Ralph White

Second Advisor

William E. Mustain

Abstract

Increasing demand for lithium-ion batteries in electric vehicles, portable electronics, and electric aircraft is a driving force for the expansion in new battery architectures to achieve higher gravimetric and volumetric efficiencies. In practice, maximizing energy density can be achieved by introducing state-of-the-art materials to increase the capacity of cells or by reducing the system's mass by incorporating lightweight structural materials. An alternative approach is to develop systems capable of performing multiple functions simultaneously that combine mono-functions of the battery and vehicular structure in a multifunctional component capable of storing electrical energy and providing structural support.

The initial focus of this study describes a dip-coating method of applying an active material to commercially available intermediate modulus carbon fibers. A suite of tools is developed to assist with the handling and coating of carbon fiber tows to create disk electrodes. Specimens of carbon fiber were dip-coated with a slurry consisting of LFP, carbon black, and polyvinylidene fluoride. Cyclic voltammetry sweeps were performed on cells to determine suitable cycling potential limits, followed by galvanostatic cycling. Then, both the anode and cathode were examined under a scanning electron microscope to establish a benchmark (anode) to compare surface topologies and analyze the quality of the active material applied via dip-coating (cathode).

A secondary focus was to analyze the energy density of three additional active materials, namely LCO, NCA, and NMC to compare performance with LFP at a rate of C/5. The cells were prepared with a polymer separator and liquid electrolytes and assembled in 2025-coin cells. Finally, visual and elemental analysis were performed via scanning electron microscope (SEM) and energy-dispersive x-ray (EDX) confirming desirable surface coverage and successful transfer of the active materials onto the carbon fiber tows.

Finally, a third focus of this work was to optimize the bus plate for application in a high-performance lithium ion passively propagation resistant battery pack. A two-dimensional thermal-electrical coupled steady-state physics-based finite-element model developed to analyze the nickel bus-plates of a novel 134P battery pack design. Both the positive bus plate and the negative-bus plate designs were analyzed. The study demonstrated that designing a nickel bus plate and keeping the same footprint dimensions but only rotating the fusible links can improve the internal resistance by at least 15% when all the fusible links were rotated in the direction between the cell tabs and the pack terminals.

Rights

© 2024, David Petrushenko

Download

Share

COinS