Rational Design of Electrolyte for Stable and Low-Temperature Zinc-Ion Battery

• Author / Creator

  Huang, Han

• Energy storage technology greatly influences human daily life, including the development of portable electronic devices, electric vehicles, smartwatches, etc. Researchers are seeking renewable and sustainable energy storage systems due to environmental concerns. Aqueous zinc-ion batteries are a promising energy storage system due to their low cost, high safety and environmentally friendly. The metallic Zn has the advantages of low redox potential and high theoretical capacity. However, the Zn anode suffers from serious problems with Zn dendrite growth and side reaction. The cycling stability and electrochemical performance are affected by these problems significantly. Adding organic solvent in electrolytes is a promising solution because the organic molecules can enter the solvation structure and replace water molecules, reducing water activity and inhibiting the hydrogen evolution reaction. Certain organic molecules possibly form the protective layer from the reduction reaction in the electrolyte, which the protective layer is derived from electrochemical reactions and is beneficial for uniform Zn2+ deposition.
  Chapter 1 is an overview of electrolyte engineering in zinc-ion batteries. The mechanism of Zn dendrite formation, hydrogen evolution reaction, and Zn corrosion are discussed in detail. In addition, the advantages of SEI layer formation and solvation structure manipulation are introduced. The review of electrolyte engineering is divided into three parts: highly concentrated electrolytes, organic solvents, and additives. In the additive section, the metal-ion additive, SEI layer forming additive, and surfactant additive are discussed. All these electrolyte engineering strategies are summarized and demonstrated with theoretical calculation and electrochemical performance. Challenges and objectives are also stated.
  Chapter 2 is the methodology for analyzing the solvation structure and stability of zinc ion batteries, including physical characterizations, electrochemical characterizations and computational simulations.
  Chapter 3 is a complete research project of enabling a stable zinc-ion battery by adding an organic solvent to the electrolyte. Diglyme (G2) is chosen as the organic solvent. It has affected the Zn2+ solvation structure, which inhibits the formation of Zn dendrite and hydrogen evolution reactions. Furthermore, the G2 molecule participates in the reduction reaction on the electrolyte-electrode interface, forming an organic-inorganic (ZnF2-ZnCO3- ZnSO3) layer on the Zn surface. The electrochemical performance shows high columbic efficiency and excellent stable and long cycling performance. In addition, the G2 organic solvent also expands the cell operating temperature to -18°C. The Zn//I-AC full cell with G2 solvent is capable in low-temperature conditions. A high columbic efficiency is also obtained at a low temperature.

• Subjects / Keywords

  • Low temperature
  • Zinc ion battery
  • Solvation structure manipulation

• Graduation date

  Fall 2023

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-benh-a533

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.