Structural  evolution of layered LixMnyO2: Combined neutron, NMR, and electrochemical study

A R Armstrong, A J Paterson, N Dupre, C P Gray, Peter George Bruce

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)

Abstract

The conversion upon electrochemical cycling from a layered structure to a spinel in nonstoichiometric LixMnyO2 has been studied by neutron diffraction and NMR. This process occurs in all layered lithium manganate materials, irrespective of the ion-exchange route. The high temperature of the ion exchange under reflux in n-hexanol is sufficient to promote formation of some spinel within the as-synthesized material. Upon cycling, all the different layered LixMnyO2 compounds begin to transform to a spinel. In the first 50 or so cycles, the various layered LixMnyO2 compounds behave rather differently, with a higher spinel fraction being observed for materials ion-exchanged under more extreme conditions. However, the rate of this transformation is significantly slower than was observed in stoichiometric layered LiMnO2, with only 25% spinel observed after 100 cycles. Ultimately, upon extended cycling, the entire structure will form a well-ordered spinel phase.

Original languageEnglish
Pages (from-to)1016-1023
Number of pages8
JournalChemistry of Materials
Volume19
Issue number5
DOIs
Publication statusPublished - 6 Mar 2007

Keywords

  • RECHARGEABLE LITHIUM BATTERIES
  • INTERCALATION COMPOUNDS
  • POSITIVE ELECTRODE
  • CATHODE MATERIALS
  • ION-EXCHANGE
  • LIMNO2
  • DIFFRACTION
  • PERFORMANCE
  • LI-6

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