Doctoral Dissertations

Yufang He

Abstract

"The growing interests in Lithium-ion Batteries (LIBs) have significantly accelerated the development of active materials. However, the key challenge is that electrode materials suffer from degradation, which include transition metal dissolution, solid electrolyte interphase (SEI) layer formation, and mechanical fracture. To address these issues, applying an ultrathin coating onto active materials via Atomic Layer Deposition (ALD) is an efficient way. Although numerious works have been done for active material performance improvement via ALD technology, the fundamental enhancement mechanisms of ALD coating on battery performance improvement are not yet known. Therefore, this dissertation consists of four papers, which focused on the ALD coating impact on Li intercalation, metal dissolution, Li ion diffusivity and interfacial property of SEI layer via first-principles study. Paper I explained why CeO2 coating has better performance than Al2O3 coating material via faster Li diffusion, facile intercalation, and less mechanical damage of coating. Paper II discovered an unexpected metal dissolution that ultrathin CeO2 coating intensifies the Mn dissolution of LMO and it was confirmed in several ways, including ICP-OES measurement, Mn vacancy formation energy calculation, COOP analysis, PDOS analysis, and cell level performance. Paper III revealed that the ALD CeO2 coating thickness impact on Li ion diffusivity in coated LMO is related to surface and bulk diffusion domination and phase transition of coating layers. Paper IV demonstrated that the fracture strength of inorganic components of SEI layer was higher than organic component, implying that the inorganic-organic interface can effectively block electron transport from electrolyte to anode particles to prevent futher oxidation of active materials"--Abstract, page iv.

Advisor(s)

Park, Jonghyun

Committee Member(s)

Gao, Jie
Han, Daoru Frank
Liang, Xinhua
Medvedeva, Julia E.

Department(s)

Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2019

Journal article titles appearing in thesis/dissertation

  • First-principles study of ultrathin film coating on cathode particles in lithium ion batteries
  • Discovery of an unexpected metal dissolution result and its theoretical and experimental explanation
  • First-principles study of atomic layer deposited film coating thickness impact on lithium ion diffusivity
  • First-principles study of the interfacial property of solid electrolyte interphase (SEI) layer components in lithium-ion batteries

Pagination

xiii, 123 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2019 Yufang He, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11626

Electronic OCLC #

1139525636

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