{
  "abstract": "P2-Na2/3Ni1/3Mn2/3O2 is a promising cathode for sodium-ion batteries, yet its electrochemical behavior is governed by a complex sequence of structural transformations whose microscopic origins remain poorly understood. In particular, Na+/vacancy ordering is expected to play a central role in the phase evolution but is challenging to resolve using powder diffraction alone. Here, we combine continuous-rotation 3D electron diffraction (3D-ED) with operando and ex situ synchrotron X-ray diffraction (SXRD) to establish a comprehensive structural picture of NaxNi1/3Mn2/3O2 across the full electrochemical window (1.0 V – 4.5 V). 3D-ED resolves Na+/vacancy ordering in sub-micrometer crystallites, revealing ordered P2 structures at Nax = 2/3, 1/2, and 1/3. In each case, Na+/vacancy ordering lowers the symmetry of the parent P2 framework and produces arrangements that minimize electrostatic repulsion while satisfying Pauling’s second rule. Transient phases at Nax = 3/5 and 2/5 are also observed during charging, while two highly sodiated P2 phases are accessed by discharging to low voltages. At high states of charge, extensive Na+ removal drives the P2→O2 transition and produces pronounced stacking disorder, demonstrating that the layer glide is not fully coherent. Bond-valence analysis further tracks transition-metal charge compensation during Na+ extraction. Together, these results establish Na+/vacancy ordering as a key structural variable governing phase stability, charge compensation, and structural transformations in P2-Na2/3Ni1/3Mn2/3O2, while highlighting 3D-ED as a powerful approach for resolving complex ordering phenomena in battery materials.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Chemistry",
    "University of Houston",
    "Texas Center for Superconductivity, University of Houston",
    "Rigaku Americas",
    "Stanford Synchrotron Radiation Lightsource",
    "SLAC National Accelerator Laboratory"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 8,
  "authors": [
    {
      "affs": [
        0,
        1,
        2
      ],
      "name": "Hasindhi H. Lokuge"
    },
    {
      "affs": [
        0,
        1,
        2
      ],
      "name": "Kusalvin Dabare"
    },
    {
      "affs": [
        0,
        1,
        2
      ],
      "name": "Jason J. Zhou"
    },
    {
      "affs": [
        0,
        1,
        2
      ],
      "name": "Moinak Dutta"
    },
    {
      "affs": [
        3
      ],
      "name": "Mark Del Campo"
    },
    {
      "affs": [
        4,
        5
      ],
      "name": "Claire E. Casaday"
    },
    {
      "affs": [
        4,
        5
      ],
      "name": "Molleigh B. Preefer"
    },
    {
      "affs": [
        0,
        1,
        2
      ],
      "name": "Joshua D. Bocarsly",
      "orcid": "0000-0002-7523-152X"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/fg848d46ca1wv.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15010983/v1",
  "fulltext_url": null,
  "id": "fg848d46ca1wv",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010983/v1",
  "language": null,
  "licence": "CC-BY-NC-ND",
  "licence_label": "CC BY-NC-ND",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2208|Advancements in Battery Materials"
    ]
  ],
  "openalex": "W7223395741",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15010983/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-23",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/fg848d46ca1wv.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:26Z",
      "native_id": "10.26434/chemrxiv.15010983",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010983/v1"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "source:chemrxiv",
      "subfield": "general"
    }
  ],
  "title": "Structural evolution of the P2-Na2/3Ni1/3Mn2/3O2 sodium-ion battery cathode material resolved by 3D electron diffraction",
  "title_text": "Structural evolution of the P2-Na2/3Ni1/3Mn2/3O2 sodium-ion battery cathode material resolved by 3D electron diffraction",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:26Z",
  "url": "https://research.draconitic.com/paper/fg848d46ca1wv",
  "venue": "ChemRxiv",
  "versions": []
}