Date of Graduation

Spring 2024

Degree

Master of Science in Materials Science

Department

Physics, Astronomy, and Materials Science

Committee Chair

Daniel Moreno

Abstract

Batteries are a foundational technology in some of the industries most essential to humanity. Often, their advancement to achieve better performance impacts human lives positively. There are a wide variety of battery chemistries that have been utilized, and the differences in their properties have caused them to be used in many distinct niche applications. Nickel-Zinc (NiZn) batteries are desirable because of their recyclable materials, high cell voltage, and high cycle-life. However, it experiences undesirable shape-change of its electrode materials and gas production due to the electrolysis of the aqueous electrolyte. These can lead to a decrease in capacity over many cycles and an increase in the resistance of the electrolyte, causing energy loss when cycling. The gasses produced in a NiZn cell are diatomic hydrogen (H2) and oxygen (O2) that must be either vented or recombined into water with an internal catalyst. There is a lack of work done to study the gassing behavior of a NiZn cell during cycling. An understanding of the gassing mechanisms may help with their mitigation. In this project, I created a computational model that primarily incorporates Butler-Volmer kinetics and the Nernst equation to simulate gas production from a NiZn cell while cycling at different rates. I also developed a method to sample the gas produced from a NiZn cell while cycling and measure its composition with a quadrupole mass spectrometer. In both, H2 was produced at the nickel cathode while discharging, but no O2 was produced. Both gasses were produced during charging with H2 being produced at the zinc anode the entire charge and O2 being produced rapidly at the cathode towards the end of charge. Recombination events of these gasses at a platinum catalyst in the cell was well identified during cycling. The model proved to be insightful when making predictions on NiZn gassing behavior, and its results agreed with experimental data. The mass spectrometer was shown to be a powerful tool for the identification of gas production and recombination of a NiZn cell.

Keywords

nickel-zinc, battery, gas evolution, mass spectrometer, electrochemical, modeling

Subject Categories

Engineering Physics | Materials Chemistry | Physical Sciences and Mathematics

Copyright

© Niklas Landgraf

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