Relationship between the crystal structures of LiMn1.5Ni0.5O4 and LiMn1.5Ni0.45Fe0.05O4 and their internal resistances as cathode materials for lithium ion batteries

Ryosuke Okamoto, Kazuhide Hayashi, Satoshi Matsumoto, Naomi Suzuki, Masami Terauchi

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

It has been reported that the partial substitution of Fe for Ni in LiMn1.5Ni0.5O4 improves the rate capability of batteries wherein it is used as a cathode material. To understand the mechanism of this improvement, LiMn1.5Ni0.5O4 and LiMn1.5Ni0.45Fe0.05O4 samples were prepared to compare their crystal structures and the internal resistances of batteries fabricated using them. Electrochemical measurements showed that resistance of LiMn1.5Ni0.45Fe0.05O4 to the diffusion of Li+ ions into bulk is lower than that for LiMn1.5Ni0.5O4. The crystal structures of LiMn1.5Ni0.5O4 and LiMn1.5Ni0.45Fe0.05O4 were examined by neutron diffraction and transmission electron microscopy. The mass percentage of the ordered P4332 phase in LiMn1.5Ni0.45Fe0.05O4 was found to be smaller than that in LiMn1.5Ni0.5O4, and the coexistence of an ordered P4332 phase and a disordered Fd3 ¯ m phase leads to the formation of boundaries in the primary particles of the samples. From these results, it was proposed that the reason for the internal resistance improvement was that the boundaries between the P4332 and Fd3 ¯ m phase impeded the diffusion of Li+ ions. Therefore, LiMn1.5Ni0.45Fe0.05O4 exhibited lower internal resistance because it contained a lower amount of P4332 phase and consequently, a lower occurrence of boundaries.

Original languageEnglish
Pages (from-to)3301-3314
Number of pages14
JournalJournal of Solid State Electrochemistry
Volume21
Issue number11
DOIs
Publication statusPublished - 2017 Nov 1

Keywords

  • Cation ordering
  • Dark-field image
  • Diffusion of Li ions
  • High-voltage cathode material
  • Neutron diffraction
  • Transmission electron microscopy

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Electrochemistry
  • Electrical and Electronic Engineering

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