High-Performance and Low-Temperature-Available Zinc-Metal Battery  Enabled by Advanced Electrolyte Strategy
Creators: Chai, Ziwei
Publisher: name: University of Alberta Library
Year: 2024

<p>The large-scale development of renewable energy is an effective means to address issues such as <br>
environmental pollution, resource depletion, safety hazards, and dependency associated with <br>
fossil fuels. On the other hand, aqueous zinc metal batteries, capable of storing large amounts of <br>
renewable energy such as wind power, have advantages such as high theoretical energy density, <br>
environmental friendliness, abundant zinc reserves, and high safety. However, due to the low <br>
decomposition voltage of aqueous electrolytes, the operating voltage of water-based batteries is <br>
generally not expected to exceed 1.23V. Furthermore, most positive electrode materials or their <br>
intermediate products during charge and discharge processes are slightly soluble in mildly acidic <br>
aqueous electrolytes, leading to structural damage of the materials and rapid deterioration of <br>
battery performance. Therefore, the selection of positive electrode materials and the <br>
enhancement of positive electrode performance through the design of compatible electrolytes are <br>
particularly crucial.<br>
Chapter 1 offers a concise yet comprehensive overview of cathode engineering, with a focus on <br>
electrolyte-based designs for aqueous zinc-metal batteries. It delves into the formation of zinc <br>
by-products at the cathode and the significant dissolution of cathode materials. Cathode <br>
engineering encompasses not only ex-situ post-synthesis modifications to the cathode material <br>
but also strategies based on electrolyte design. The electrolyte-oriented cathode engineering <br>
strategies discussed in this review include highly concentrated electrolytes, additives, and <br>
organic co-solvents. The review also incorporates theoretical calculations, characterization <br>
results, and electrochemical performance data from the literature to support the explanation of <br>
these strategies. Challenges and objectives are clearly delineated.<br>
I<br>
Chapter 2 outlines methodologies for investigating the interaction of molecules in electrolytes, <br>
inhibiting the formation of zinc by-products, and understanding the dissolution of active <br>
materials in zinc-metal batteries. This encompasses physical characterizations (such as TEMEDS, XRD, ICP-OES), electrochemical analyses (including rate performance, cyclic <br>
voltammetry, low-temperature testing), and computational simulations (such as molecular <br>
dynamics).<br>
Chapter 3 presents a comprehensive research project aimed at stabilizing zinc-metal batteries by <br>
suppressing cathode dissolution through the addition of an organic co-solvent to the electrolyte. <br>
Methyl acetate (MA) is chosen as the organic co-solvent to protect the Prussian Blue Copper <br>
(CuHCF) cathode. The incorporation of MA co-solvent (75% vol.) effectively and directly <br>
coordinates with water molecules. This modification influences the electrolyte&#39;s water activity, <br>
thereby suppressing side reactions and the dissolution of active materials at the cathode surface. <br>
Electrochemical evaluation demonstrates notable achievements in terms of high columbic <br>
efficiency and remarkable stability over extended cycling. Additionally, the low viscosity and <br>
freezing point of the MA co-solvent facilitate the operation of zinc-metal batteries under <br>
extremely low-temperature conditions. For example, the CuHCF//Zn battery exhibits <br>
functionality at temperatures as low as -50℃, maintaining high columbic efficiency and <br>
prolonged cycling life even under such challenging conditions.</p>