Electrochemical Mg-ion Activity in MgCr2-xVxO4 Spinel Oxides

(a) 25Mg NMR spectra of various MgCr2-xVxO4 spinel oxides, (b) Mn K-edge of pristine and charged MgCrVO4, (c) HRXRD patterns of different states of charges of MgCrVO4 and (d) representative voltage versus capacity profiles of MgCrVO4 paired with a Mg metal foil in Mg(TPFA)2 electrolyte at 110°C.

Scientific Achievement

Bulk demagnesiation in MgCrVO4 spinel lattice is observed in a full-cell configuration paired with a Mg metal anode in a chemically and anodically stable Mg(TPFA)2 electrolyte at 110 oC.

Significance and Impact

Solid solution MgCr2-xVxO4 spinel was designed and characterized by theoretical and experimental analyses as a cathode for Mg-ion batteries. We find bulk Mg2+ activity in the designed oxide with partial reversibility in a Mg-ion full-cell configuration. Fundamental mechanisms for reversible Mg2+ intercalation into the high voltage spinel oxides and other irreversible phenomena were proposed by a suite of structural characterization methods. This system provides a step forward in high voltage oxide material design for Mg-ion batteries.

Research Details

  • Materials characterization establishing a conclusive proof of bulk Mg2+ reactivity in MgCrVO4 without H+ or H2O co-insertion.
  • Mg(TPFA)2 electrolyte at elevated temperatures mitigates kinetic limitations of Mg2+.

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DOI: 10.1021/acs.chemmater.9b04206

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