Conductivity and electrochemical behavior of Li1-xFe1-2x(MIIMIII) xPO4 with olivine structure

Roman Kapaev, Svetlana Novikova, Tatiana Kulova, Alexander Skundin, Andrey Yaroslavtsev

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Lithium iron phosphates with olivine structure doped by trivalent cations and co-doped by divalent and trivalent cations of the compositions Li1-xFe1-xMIII xPO4 (MIII = Al, Cr, Ga, Y, In) and Li1-xFe1-2x(NiMIII)xPO4 (MIII = Al, In) were prepared by the sol-gel method. Structure, morphology, and conductivity of the prepared materials were studied by the X-ray diffraction analysis, scanning electron microscopy, and impedance spectroscopy. The solubility of M3+ cations in LiFePO4 with olivine structure was estimated. Single-phase samples were shown to be preserved at x ≤ 0.05 for Cr3+ and Al3+ cations, at x ≤ 0.02 for In3+, and at x ≤ 0.005 for Ga3+ and Y3+ cations. The materials doped with M3+ and co-doped with both M2+ and M3+ cations were characterized by a higher ionic conductivity and by a lower activation energy of ionic conductivity. Carbon-coated materials Li0.995Fe0.99(NiM)0.005PO4/C (MIII = Al, In) were prepared, and their electrochemical behavior was studied using the charge/discharge tests. Due to LiFePO4 co-doping with M2+ and M3+ cations, capacity slightly decreases but the charge/discharge rate increases.

Original languageEnglish
Pages (from-to)2793-2801
Number of pages9
JournalJournal of Solid State Electrochemistry
Volume19
Issue number9
DOIs
StatePublished - 5 Sep 2015
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2015, Springer-Verlag Berlin Heidelberg.

Keywords

  • Cathode materials
  • Doping
  • Ion conductivity
  • Lithium ion battery
  • Lithium iron phosphate
  • Rate capability

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