IR near-field spectroscopy and imaging of single LixFePO4 microcrystals

I. T. Lucas, A. S. McLeod, J. S. Syzdek, D. S. Middlemiss, C. P. Grey, D. N. Basov, R. Kostecki

Research output: Contribution to journalArticlepeer-review

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This study demonstrates the unique capability of infrared near-field nanoscopy combined with Fourier transform infrared spectroscopy to map phase distributions in microcrystals of LixFePO4, a positive electrode material for Li-ion batteries. Ex situ nanoscale IR imaging provides direct evidence for the coexistence of LiFePO4 and FePO4 phases in partially delithiated single-crystal microparticles. A quantitative three-dimensional tomographic reconstruction of the phase distribution within a single microcrystal provides new insights into the phase transformation and/or relaxation mechanism, revealing a FePO4 shell surrounding a diamond-shaped LiFePO4 inner core, gradually shrinking in size and vanishing upon delithiation of the crystal. The observed phase propagation pattern supports recent functional models of LiFePO4 operation relating electrochemical performance to material design. This work demonstrates the remarkable potential of near-field optical techniques for the characterization of electrochemical materials and interfaces.

Original languageEnglish (US)
Pages (from-to)1-7
Number of pages7
JournalNano letters
Issue number1
StatePublished - Jan 14 2015
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2014 American Chemical Society.


  • IR s-SNOM
  • Li-ion batteries
  • LiFePO
  • phase distribution


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