Master's Theses

Date of Award

2017

Document Type

Thesis

Department

Chemical Engineering

First Advisor

Elizabeth J. Biddinger

Keywords

Battery, Electrolyte, Conductivity, Safety

Abstract

The increased capacity of the modern battery system has also brought about safety apprehensions. Uncontrollable runaway reactions are a big concern in these systems; these reactions are the result of in situ heat generation and very much increase the risk of explosions and device failures. The concept of this work is to provide a preliminary understanding into the use of a type of switchable solvent known as reversible ionic liquids (RevILs) and their feasibility in being used in electrolytes as a thermally-controlled reversible safety switch. In their pure forms these switchable solvents experience a dramatic change in their properties upon introduction of an external stimulus, in this case temperature and CO2. This thesis investigated the properties of 3-aminopropyl trialkylsilylamine RevILs (TEtSA, TPSA, and THSA). Conductivities of these RevILs when mixed with organic solvents were studied. It was found that when protic methanol and aprotic DMSO were used as solvents, the conductivities of these solutions increased dramatically in their RevIL form but remained essentially non-conductive in their molecular liquid state. Conductivity was also found to have a decreasing trend as the alkyl chain length was increased on the molecule. The addition of zinc salts like zinc chloride and zinc acetate dihydrate were also found to increase conductivities 20-40% for a 5mol% TEtSA-RevIL DMSO solution. A Walden plot analysis was conducted on the TEtSA RevIL solution to evaluate the ionicity of the system. The ionicity analysis suggested a dissociation of ions that approached 1% ideal ionicity.

Available for download on Friday, November 24, 2017

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