University of Illinois Urbana-Champaign

Nanoscale defect engineering and mapping for cathode materials of multivalent ion batteries

Tang, Zhichu

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https://hdl.handle.net/2142/130132

Description

Title
Nanoscale defect engineering and mapping for cathode materials of multivalent ion batteries
Author(s)
Tang, Zhichu
Issue Date
2025-07-07
Director of Research (if dissertation) or Advisor (if thesis)
Chen, Qian
Doctoral Committee Chair(s)
Chen, Qian
Committee Member(s)
  • Zuo, Jian-Min
  • Braun, Paul V.
  • Yang, Hong
Department of Study
Materials Science & Engineerng
Discipline
Materials Science & Engr
Degree Granting Institution
University of Illinois Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • Defect engineering
  • Zn-ion battery
  • Energy storage
  • 4D-STEM
  • Nanomaterial characterization
Abstract
Aqueous multivalent ion batteries, particularly Zn-ion batteries (ZIBs), represent a promising next-generation solution for grid-scale energy storage. However, their practical application is hindered by the lack of suitable cathode materials that can support reversible Zn-ion intercalation, as well as an incomplete understanding of their fundamental reaction mechanisms. This thesis aims to address these challenges by advancing nanoscale characterization techniques and offering fundamental insights into how particle size reduction and stacking fault (SF) engineering enhance Zn-ion diffusion within the spinel lattice. Chapter 1 provides a brief introduction to manganese-based oxides as cathode materials for ZIBs and outlines the remaining scientific and technical challenges. Chapter 2 investigates the influence of particle size on the phase transition pathways of λ-MnO2 during Zn-ion insertion, along with water-induced side reactions. We find that although Zn-ion insertion is enhanced in nanoparticles (NPs), their extraction from the spinel lattice is still difficult, leading to poor cycling stability. To address this limitation, Chapter 3 presents a novel method to improve the cycling performance of λ-MnO2 NPs in ZIBs by introducing SFs via thermal treatment. These SF defects are identified and quantified at nanometer resolution using four-dimensional scanning transmission electron microscopy (4D-STEM). Collocated 4D-STEM and electron energy loss spectroscopy (EELS) mapping reveals SFs enable reversible Zn-ion insertion and extraction in the spinel lattice. The thermal-induced phase transition pathway and the underlying mechanism by which SFs promote Zn-ion extraction are discussed in Chapter 4. We further extend the 4D-STEM technique and associated data-mining methods to other battery systems, demonstrating the effect of Na+ on Li-Na ion exchange in LiFePO4 through strain mapping. Finally, Chapter 5 summarizes the key findings and proposes future research directions, emphasizing the potential of integrating 4D-STEM with in-situ liquid-phase transmission electron microscopy to investigate ion transport and structural evolution in real time. These advances provide a powerful platform for the fundamental study and rational design of intercalation-type cathode materials for next-generation energy storage systems.
Graduation Semester
2025-08
Type of Resource
Thesis
Handle URL
https://hdl.handle.net/2142/130132
Copyright and License Information
Copyright 2025 Zhichu Tang

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Graduate Theses and Dissertations at Illinois