Synthesis, cathode property and crystal, electronic and local structures of Mg2Mo3O8 as Mg rechargeable battery cathode material

Naoya Ishida, Yuta Nakamura, Toshihiko Mandai, Naoto Kitamura, Yasushi Idemoto

Research output: Contribution to journalArticlepeer-review

Abstract

Mg2Mo3O8 was synthesized by a solid-phase method in a high vacuum atmosphere. According to the combination of ICP-AES technique and Rietveld analysis for synchrotron X-ray and neutron diffraction patterns, the structure and composition of the synthesized material was identified as single phase of the layered Mg2Mo3O8 of P63mc space-group. Charge and discharge cycle tests showed that Mg2Mo3O8 with carbon composite exhibited 18 and 89 mAh g−1 of initial charge and discharge capacities at 90 °C. Reversible charge/discharge behavior was confirmed up to 5 cycles. Electrochemical demagnesiation using Li anode showed deintercalation of 0.45 Mg2+ pfu. The valence of the Mo in synthesized material was determined by XAFS, whose spectrum at the Mo K-edge confirmed the reductive synthesis of Mg2Mo3O8 because of not hexavalent but reduced tetravalent Mo. Since the Mo K-edge XANES spectrum after first charge was oxidized from tetravalent, it was revealed that the Mg2Mo3O8 could electrochemically demagnesiate in the present cell-condition using [Mg(G4)][TFSA]2/[PYR13][TFSA] electrolyte. The PDF data from synchrotron X-ray total scattering was used to analyze the local structure. The local structure leads to the Mg hopping route in Mg2Mo3O8, where tetrahedrally coordinated Mg hops via octahedral site.

Original languageEnglish
Article number115413
JournalSolid State Ionics
Volume354
DOIs
Publication statusPublished - 15 Oct 2020

Keywords

  • Cathode material
  • Layered magnesium molybdenum oxide
  • Magnesium rechargeable battery
  • PDF analysis
  • Rietveld analysis

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