Degradation diagnosis of aged Li4Ti5O 12/LiFePO4 batteries

Rémi Castaing, Yvan Reynier, Nicolas Dupré, Donald Schleich, Séverine Jouanneau Si Larbi, Dominique Guyomard, Philippe Moreau

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Li4Ti5O12/LiFePO4 cells are cycled under 4 different conditions of discharge profile (galvanostatic or driving-based) and cycling rates (C/8 or 1C) during 4-5 months. All the cells exhibit capacity fade whose extent is not correlated with the aging condition. In order to understand aging phenomena, cells are disassembled at the end of cycle life and the recovered electrodes are analyzed using electrochemistry, electron microscopy, XRD and MAS-NMR. Positive and negative electrodes show no loss in active material and no change in electrochemical activity, active material structure and composite electrode structure. This rules out any irreversible electrode degradation. Lithium stoichiometry estimated by both XRD and electrochemistry is unexpectedly low in the positive electrode when the aging is stopped at full discharge. That indicates a loss of cyclable lithium or electrons leading to cell balancing evolution. That loss may have been caused by parasitic reactions occurring at both electrodes, in accordance with their rich surface chemistry as evidenced by MAS-NMR.

Original languageEnglish
Pages (from-to)744-752
Number of pages9
JournalJournal of Power Sources
Volume267
Early online date9 Jun 2014
DOIs
Publication statusPublished - 1 Dec 2014

Keywords

  • Aging
  • Electric vehicle
  • End of charge/discharge slippage
  • Lithium battery

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Physical and Theoretical Chemistry
  • Electrical and Electronic Engineering

Cite this

Castaing, R., Reynier, Y., Dupré, N., Schleich, D., Jouanneau Si Larbi, S., Guyomard, D., & Moreau, P. (2014). Degradation diagnosis of aged Li4Ti5O 12/LiFePO4 batteries. Journal of Power Sources, 267, 744-752. https://doi.org/10.1016/j.jpowsour.2014.06.002