Composition and Manufacturing Effects on Electrical Properties of Li/FeS2 Thermal Battery Cathodes
type: CreativeWork
description: Li/FeS2 thermal batteries provide a stable, robust, and reliable power source capable of long-term electrical energy storage without performance degradation. These systems rely on a eutectic salt that melts at elevated temperature, activating the cell. When the electrolyte melts, the cathode becomes a suspension, with cathode particles suspended in a molten salt. The suspension experiences mechanical deformation, or slumping.' This slump changes the mechanical compression of the cell, as well as the tortuosity and electronic and ionic conductivity of the cell as the cathode mesostructure is reordered in response to the external compressive stress. The combined effect of deformation, component composition, and manufacturing conditions on electrical conductivity has not been studied, yet the cathode electrical properties are critically important to battery performance. This thesis presents simulation results from a computer model in combination with experiments to elucidate the effects of electrical conductivity in FeS2 cathode pellets when composition and manufacturing parameters are varied. Experiments applied impedance spectroscopy measurements of pressed-powder cathode pellets before and after slumping. Pellets were manufactured with variations in pellet density, FeS2 particle size distribution, and FeS2 content. The results showed that prior to slumping, the electrical conductivity increased with pellet density and FeS2 content. After slumping, pellets exhibited greater electrical conductivity, but the effects of processing parameters appear to have been erased, at least within the ranges tested. The conformal decomposition finite element method (CDFEM) was applied to surface-meshed geometric representations of cathode microstructures generated from microcomputed tomography reconstructions. Results from the SIERRA/Aria finite element code indicate that the selected processing and composition parameters do not provide a clear trend on the preslumped electrical con…
abstract: Li/FeS2 thermal batteries provide a stable, robust, and reliable power source capable of long-term electrical energy storage without performance degradation. These systems rely on a eutectic salt that melts at elevated temperature, activating the cell. When the electrolyte melts, the cathode becomes a suspension, with cathode particles suspended in a molten salt. The suspension experiences mechanical deformation, or slumping.' This slump changes the mechanical compression of the cell, as well as the tortuosity and electronic and ionic conductivity of the cell as the cathode mesostructure is reordered in response to the external compressive stress. The combined effect of deformation, component composition, and manufacturing conditions on electrical conductivity has not been studied, yet the cathode electrical properties are critically important to battery performance. This thesis presents simulation results from a computer model in combination with experiments to elucidate the effects of electrical conductivity in FeS2 cathode pellets when composition and manufacturing parameters are varied. Experiments applied impedance spectroscopy measurements of pressed-powder cathode pellets before and after slumping. Pellets were manufactured with variations in pellet density, FeS2 particle size distribution, and FeS2 content. The results showed that prior to slumping, the electrical conductivity increased with pellet density and FeS2 content. After slumping, pellets exhibited greater electrical conductivity, but the effects of processing parameters appear to have been erased, at least within the ranges tested. The conformal decomposition finite element method (CDFEM) was applied to surface-meshed geometric representations of cathode microstructures generated from microcomputed tomography reconstructions. Results from the SIERRA/Aria finite element code indicate that the selected processing and composition parameters do not provide a clear trend on the preslumped electrical con…
author: Reinholz, Emilee Lolita
language: English
keywords: thermal batteries, processing, manufacturing, finite element method, impedance spectroscopy, microstructure, 3D, microcomputed tomography
date published: 2016-02-01T08:00:00Z
date modified: 2026-07-24T05:26:42Z
provider: University of New Mexico
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of New Mexico

PropertyValue
property ID: Handle
value: http://hdl.handle.net/1928/31688