Interfacial electrochemo-mechanical studies of nano/microstructures in lithium-ion batteries

Jeong, Hyewon

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https://hdl.handle.net/2142/130178 Copy

Description

Title

Interfacial electrochemo-mechanical studies of nano/microstructures in lithium-ion batteries

Author(s)

Jeong, Hyewon

Issue Date

2025-07-18

Director of Research (if dissertation) or Advisor (if thesis)

Braun, Paul

Doctoral Committee Chair(s)

Braun, Paul

Committee Member(s)

• Zuo, Jian-Min
• Krogstad, Jessica Anne
• Wang, Pingfeng

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)

• electrochemo-mechanics
• silicon anodes
• solid-state batteries
• engineering CEI (cathode-electrolyte interphase)
• scanning transmission electron microscopy (STEM)

Abstract

1. Nickel current collector | Silicon (anode) Silicon has emerged as a promising anode material due to its high lithium storage capacity. While commercial batteries may now include silicon particles, porous three-dimensional (3D) scaffolded silicon electrodes may enable higher silicon loading by providing space to accommodate the silicon volume expansion during alloying with lithium without significant electrode swelling. However, the electrochemo-mechanical response of silicon film on a metal scaffold is not well understood due to the complex morphology of the scaffold. Here we explore the role of scaffold curvature on the cycling behavior of silicon films and show that different curvatures exhibit distinctive silicon failure modes. Negative curvature shows tensile and compressive stress driven-crack opening failure. Positive curvature is correlated with tensile stress driven buckling. Zero curvatures (a flat surface) exhibit fragmentation. The detailed electrode morphology and chemistry for these systems is evaluated via scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (STEM-EDS). COMSOL Multiphysics simulations also show the electrochemo-mechanics of silicon are curvature-dependent. These findings point the way towards design strategies for next-generation 3D architected silicon anodes with improved cycling integrity. 2. Lithium cobalt oxide, LiCoO2 (cathode) | Lithium indium chloride, Li3InCl6 (LIC, solid-electrolyte) All-solid-state batteries (ASSBs) are emerging as a promising energy storage solution due to their enhanced safety, high energy density, and improved performance over conventional lithium-ion batteries (LIBs). The use of solid electrolytes, such as sulfides, oxides, or halides, helps mitigate issues like leakage, flammability, and dendrite formation typically associated with liquid-electrolyte systems. In this thesis, layered LiCoO2 (LCO) cathodes and Li3InCl6 (LIC) solid-electrolytes were selected for their high energy density and oxidation stability. Our study via scanning transmission electron microscopy (STEM) reveals that a spinel structure forms uniformly (~15 nm) on the LCO surface over extended cycling at high temperatures, leading to performance degradation. Through various testing conditions—including voltage holding, resting, and different charge rates—we identified that the spinel phase nucleates under electrochemical influence at high temperatures, during fast charging at room temperature, and at high states of charge. This phenomenon is corroborated by electrochemical impedance spectroscopy (EIS), which shows a growth in interfacial resistance in the presence of the spinel phase. These findings provide valuable insights into the origins of spinel formation and its role in the accelerated degradation of solid-state batteries.

Graduation Semester

2025-08

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/130178

Copyright and License Information

Copyright 2025 Hyewon Jeong

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