Experimental evaluation of influence of stress on li chemical potential and phase equilibrium in two-phase battery electrode materials

Yuta Kimura, Keita Funayama, Mahunnop Fakkao, Takashi Nakamura, Naoaki Kuwata, Tatsuya Kawada, Junichi Kawamura, Koji Amezawa

Research output: Contribution to journalArticlepeer-review

Abstract

We experimentally evaluated the influence of stress on the Li chemical potential (μLi) and phase equilibrium in the two-phase battery electrode materials through the emf measurements while applying a mechanical load. In our measurements, we prepared an electrochemical cell by depositing a thin film of a two-phase electrode material (LiFePO4 or LiCoO2 in the two-phase region) on each of the solid electrolyte surfaces. Then we applied a mechanical load to the electrochemical cell through four-point bending, and the resulting μLi variation in the electrode material was measured as the emf between the two thin films. Our results indicated that μLi in the two-phase electrode materials immediately changed just after loading and then gradually changed while maintaining a constant mechanical load. Besides, the loading and unloading led to the μLi variation in the opposite direction. Such characteristic μLi variations could be explained by considering the change in the phase equilibrium between the two phases, which led to the Li content variation in the two phases and the stress relaxation due to the volume fraction variation of the two phases. Our results can provide valuable insights regarding the influence of stress on the performances of energy storage devices with two-phase electrode materials.

Original languageEnglish
Pages (from-to)355-362
Number of pages8
JournalElectrochemistry
Volume89
Issue number4
DOIs
Publication statusPublished - 2021
Externally publishedYes

Keywords

  • Li chemical potential
  • Phase equilibria
  • Stress
  • Two-phase battery electrode materials

ASJC Scopus subject areas

  • Electrochemistry

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