Intercalation of Ca into a Highly Defective Manganese Oxide at Room Temperature

(a) Potential versus capacity profiles of MnOx cycled at 25℃ and 60 ℃, (b) Mn K-edge XAS of MnOx at different states of charges prepared at 25 ℃ and (c) PDF analyses for MnOx at various states of charge.

Scientific Achievement

Nanocrystals of layered MnOx containing a high concentration of atomic defects and lattice water are shown to have remarkable electrochemical activity towards Ca2+ , amounting to a capacity of ~130 mAh/g at room temperature. Multimodal characterization revealed the notable degree of intercalation by probing the structural, compositional and redox changes undertaken by the defective MnOx nanocrystals.

Significance and Impact

Our results uncover a new candidate for a cathode in Ca-ion batteries operated by an intercalation mechanism at moderate temperatures, and cast light onto a structural family whose very high diversity makes it an attractive playground for further exploration.

Research Details

  • The local structure of MnOx was found to contain a large concentration of interlayer Mn defects, creating clustering of walls that resembled the triple chains of todorokite.
  • The observation of a virtually complete loss of activity upon dehydration and crystallization hints at the critical role of defects and lattice water within the nanocrystals in facilitating the migration of Ca2+.

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DOI: 10.1021/acs.chemmater.1c03803


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