Oriented LiMn2O4 particle fracture from delithiation-driven surface stress

Jeffrey Greeley*, Robert E. Warburton, Fernando C. Castro, Siddharth Deshpande, Kenneth E. Madsen, Kimberly L. Bassett, Roberto Dos Reis, Andrew A. Gewirth, Vinayak P. Dravid

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

The insertion and removal of Li+ ions into Li-ion battery electrodes can lead to severe mechanical fatigue because of the repeated expansion and compression of the host lattice during electrochemical cycling. In particular, the lithium manganese oxide spinel (LiMn2O4, LMO) experiences a significant surface stress contribution to electrode chemomechanics upon delithiation that is asynchronous with the potentials where bulk phase transitions occur. In this work, we probe the stress evolution and resulting mechanical fracture from LMO delithation using an integrated approach consisting of cyclic voltammetry, electron microscopy, and density functional theory (DFT) calculations. High-rate electrochemical cycling is used to exacerbate the mechanical deficiencies of the LMO electrode and demonstrates that mechanical degradation leads to slowing of delithiation and lithiation kinetics. These observations are further supported through the identification of significant fracturing in LMO using scanning electron microscopy. DFT calculations are used to model the mechanical response of LMO surfaces to electrochemical delithiation and suggest that particle fracture is unlikely in the [001] direction because of tensile stresses from delithiation near the (001) surface. Transmission electron microscopy and electron backscatter diffraction of the as-cycled LMO particles further support the computational analyses, indicating that particle fracture instead tends to preferentially occur along the {111} planes. This joint computational and experimental analysis provides molecularlevel details of the chemomechanical response of the LMO electrode to electrochemical delithiation and how surface stresses may lead to particle fracture in Li-ion battery electrodes.

Original languageEnglish (US)
Pages (from-to)49182-49191
Number of pages10
JournalACS Applied Materials and Interfaces
Volume12
Issue number43
DOIs
StatePublished - Oct 28 2020

Keywords

  • Chemomechanics
  • Density functional theory
  • Electron microscopy
  • Lithiation
  • Lithium ion batteries
  • Stress

ASJC Scopus subject areas

  • Materials Science(all)

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