Operando X-ray Diffraction Studies of the Mg-Ion Migration Mechanisms in Spinel Cathodes

Schematic illustration of three cation migration processes of the inverted MgCrMnO4 during the first charge/discharge. Pie charts represent the factions of cations on the tetrahedral 8a and the initially unoccupied octahedra 16c sites at the selected state of charge.

Scientific Achievement

The Mg-ion migration mechanisms in MgMnCrO4 spinel cathode was investigated experimentally through operando x-ray diffraction revealing a complex mechanism during Mg insertion/extraction.

Significance and Impact

Previous research showed the spinel cathode, MgMnCrO4, as a promising high-voltage cathode material with reversible insertion of Mg ions. However, the relationship between inversion defects and the migration mechanisms of cations during cycle was not understood.

Research Details

  • MgMnCrO4 was measured and studied structurally through synchrotron diffraction, utilizing a custom operando x-ray diffraction cell.
  • Operando diffraction revealed a complex reorganization of cations during charging and discharging. This cation migration couples with inversion defects and structure of the lattice.
  • Combining the operando diffraction with DFT computations revealed how the details of cation migration and lattice defects elucidate the nature of reversibility, voltage hysteresis and capacity loss

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DOI: 10.1021/jacs.1c04098

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