Dissertations and Theses

Date of Award


Document Type



Mechanical Engineering

First Advisor

Robert J. Messinger


batteries, aluminium, zinc, aqueous, ionic salt, MnO2


The widespread use of non-renewable fossil fuels has led to societal problems like global warming and climate change. Electrochemical energy storage can enable the integration of renewable energy sources that are inherently intermittent (solar, wind, etc.) into the electric grid, though major advances in cost, cycle life, and safety are necessary to have a global impact on the energy landscape. Both aluminium (Al) and zinc (Zn) metals are earth abundant, low-cost, safe, and exhibit high coulombic capacities, which make them promising electrode materials for “beyond lithium-ion” battery chemistries. However, the electrochemical feasibility and charge storage mechanisms of alternative Al and Zn battery systems, particularly when paired low-cost positive electrode materials, must be investigated.

In this thesis, high-energy-density aluminium and zinc metal batteries that employ low-cost and safe manganese dioxide (MnO2) as positive electrode materials (“cathodes”) are investigated using ionic liquid and aqueous electrolytes. Two crystalline polymorphs of MnO2 are used: birnessite (δ-MnO2), a layered structure, and todorokite, a seldomly studied structure composed of large tunnels. For the Al batteries, two electrolyte were used: an ionic liquid containing aluminium chloride and 1-ethyl-3-methylimidazolium chloride ionic liquid (AlCl3/Emim[Cl]), and aqueous aluminium triflate. For the Zn batteries, aqueous zinc sulfate (non-alkaline) was used. The batteries were characterized electrochemically by galvanostatic and cyclic voltammetry tests while the electrode and electrolytes materials were studied by X-ray diffraction and nuclear magnetic resonance (NMR) spectroscopic measurements. Al-MnO2 batteries using choloraluminate-containing ionic liquid electrolytes are shown to be unsuitable for rechargeable redox electrochemistry, exhibiting large capacity fade, likely due to chemical and/or electrochemical instability of MnO2 in the electrolyte. Aqueous Al-MnO2 batteries showed far more promise, exhibiting reversible electrochemical behaviour in cyclic voltammograms. The underlying charge storage mechanism appears independent of the crystalline polymorph, likely linked to proton intercalation, and requires further study. Aqueous (non-alkaline) Zn-todorokite batteries also demonstrated reversible electrochemical behaviour and thus show promise as a rechargeable battery technology. The precise role of protons and water (e.g., hydration of zinc ions) should be clarified in future investigations. Overall, this work lays part of the scientific foundation towards using and understanding crystalline MnO2 polymorphs as positive electrode materials for aqueous Al and Zn-ion batteries.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.