Electrochemical Stiffness Changes in Lithium Manganese Oxide Electrodes

Ömer Özgür Çapraz, Kimberly L. Bassett, Andrew A. Gewirth, Nancy R. Sottos

Research output: Contribution to journalArticle

Abstract

In situ strain and stress measurements are performed on composite electrodes to monitor potential-dependent stiffness changes in lithium manganese oxide (LiMn2O4). Lithium insertion and removal results in asynchronous strain and stress generation in the electrode. Electrochemical stiffness changes are calculated by combining coordinated stress and strain measurements. The electrode experiences dramatic changes in electrochemical stiffness due to potential-dependent Li+ ion intercalation mechanisms. The development of stress in the early stages of delithiation (at ≈3.95 V) due to a kinetic barrier at the electrode surface gives rise to stiffness changes in the electrode. Strain generation due to phase transformations reduces stiffness in the electrode at 4.17 V during delithiation and at 4.11 V during lithiation. During lithiation, stress generation due to Coulombic repulsions between occupied and incoming Li+ ions leads to stiffening of the electrode at 3.96 V. The electrode also experiences greater changes in stiffness during delithiation compared to lithiation. These changes in electrochemical stiffness provide insight into the interplay between mechanical and electrochemical properties which control electrode response to lithiation and delithiation.

Original languageEnglish (US)
JournalAdvanced Energy Materials
Volume7
Issue number7
DOIs
StatePublished - Apr 5 2017

Keywords

  • electrochemical stiffness
  • lithium manganese oxide
  • mechanical deformation
  • strain
  • stress

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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