{
  "node": {
    "id": "term:jahn-teller-distortion",
    "type": "Term",
    "label": "Jahn–Teller distortion",
    "properties": {
      "id": "jahn-teller-distortion",
      "name": "Jahn–Teller distortion",
      "aka": [
        "Jahn–Teller effect"
      ],
      "section": "topic-aging",
      "definition": "The elongation of a metal–oxygen octahedron around an ion with an unevenly filled d-shell, notably high-spin Mn³⁺. When LiMn₂O₄ is discharged below about 3 V vs Li/Li⁺, so many Mn³⁺ ions distort together that the crystal turns from cubic to tetragonal; the strain cracks particles, and Mn³⁺ disproportionation feeds manganese dissolution.",
      "related": [
        "lmo",
        "structural-degradation",
        "transition-metal-dissolution",
        "particle-cracking",
        "phase-transition"
      ],
      "url": "https://lemonergy.com/learn/glossary/jahn-teller-distortion/",
      "mentions": [
        "manganese"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:6581",
      "source": "term:jahn-teller-distortion",
      "target": "topic:topic-aging",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:6582",
      "source": "term:jahn-teller-distortion",
      "target": "term:lmo",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6583",
      "source": "term:jahn-teller-distortion",
      "target": "term:structural-degradation",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6584",
      "source": "term:jahn-teller-distortion",
      "target": "term:transition-metal-dissolution",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6585",
      "source": "term:jahn-teller-distortion",
      "target": "term:particle-cracking",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6586",
      "source": "term:jahn-teller-distortion",
      "target": "term:phase-transition",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/jahn-teller-distortion/manganese",
      "source": "term:jahn-teller-distortion",
      "target": "term:manganese",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-aging",
      "type": "Topic",
      "label": "Aging and degradation",
      "properties": {
        "id": "topic-aging",
        "name": "Aging and degradation",
        "lede": "Why a cell loses capacity and gains resistance, and the mechanisms behind it.",
        "context": "Separate mechanisms, observations and fitted models.",
        "example": "Capacity loss and resistance rise can have different causes; a film-growth curve cannot identify both.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/battery-aging/",
        "lesson_label": "Open aging"
      }
    },
    {
      "id": "term:lmo",
      "type": "Term",
      "label": "LMO",
      "properties": {
        "id": "lmo",
        "name": "LMO",
        "aka": [
          "lithium manganese oxide",
          "spinel"
        ],
        "section": "topic-chemistries",
        "definition": "A manganese spinel positive material, LiMn₂O₄, that is cheap, safe and good at high power but suffers manganese dissolution and short life at elevated temperature. It is often blended with NMC rather than used alone.",
        "related": [
          "transition-metal-dissolution",
          "nmc",
          "cathode-active-material",
          "lnmo"
        ],
        "url": "https://lemonergy.com/learn/glossary/lmo/",
        "mentions": [
          "manganese"
        ]
      }
    },
    {
      "id": "term:structural-degradation",
      "type": "Term",
      "label": "Structural degradation",
      "properties": {
        "id": "structural-degradation",
        "name": "Structural degradation",
        "aka": [
          "phase transformation",
          "cation mixing"
        ],
        "section": "topic-aging",
        "definition": "Changes in the crystal structure of a positive material as it cycles: layered oxides can rearrange into spinel or rock-salt phases at the surface, with nickel ions migrating into lithium sites. The new phases block lithium transport and raise resistance.",
        "related": [
          "high-nickel",
          "phase-transition",
          "impedance-rise",
          "loss-of-active-material"
        ],
        "url": "https://lemonergy.com/learn/glossary/structural-degradation/",
        "mentions": [
          "lmo"
        ]
      }
    },
    {
      "id": "term:transition-metal-dissolution",
      "type": "Term",
      "label": "Transition-metal dissolution",
      "properties": {
        "id": "transition-metal-dissolution",
        "name": "Transition-metal dissolution",
        "section": "topic-aging",
        "definition": "Manganese, nickel or cobalt ions leaching from the positive electrode into the electrolyte, especially at high voltage and temperature or when HF is present. They migrate to the negative electrode and poison the SEI there, accelerating lithium loss.",
        "related": [
          "lmo",
          "hydrofluoric-acid",
          "sei",
          "loss-of-active-material",
          "crosstalk"
        ],
        "lesson": "fundamentals/battery-aging/#crystals",
        "url": "https://lemonergy.com/learn/glossary/transition-metal-dissolution/",
        "mentions": [
          "electrode",
          "negative-electrode",
          "positive-electrode",
          "electrolyte",
          "cobalt",
          "leaching",
          "manganese"
        ]
      }
    },
    {
      "id": "term:particle-cracking",
      "type": "Term",
      "label": "Particle cracking",
      "properties": {
        "id": "particle-cracking",
        "name": "Particle cracking",
        "section": "topic-aging",
        "definition": "Fracture of active-material particles from the volume change of repeated lithium insertion and removal. New surfaces consume electrolyte to form fresh SEI, and fragments that lose contact no longer store lithium.",
        "related": [
          "cycle-aging",
          "loss-of-active-material",
          "silicon-anode",
          "single-crystal",
          "depth-of-discharge"
        ],
        "lesson": "fundamentals/battery-aging/#cracking",
        "url": "https://lemonergy.com/learn/glossary/particle-cracking/",
        "mentions": [
          "electrolyte",
          "sei"
        ]
      }
    },
    {
      "id": "term:phase-transition",
      "type": "Term",
      "label": "Phase transition",
      "properties": {
        "id": "phase-transition",
        "name": "Phase transition",
        "aka": [
          "staging"
        ],
        "section": "topic-electrochemistry",
        "definition": "A change of crystal structure as lithium content varies, which fixes the potential while two phases coexist. Graphite fills in stages, LFP switches between two phases across almost its whole range, and these transitions make the peaks that aging diagnostics read.",
        "related": [
          "voltage-plateau",
          "differential-voltage-analysis",
          "lfp",
          "graphite",
          "structural-degradation"
        ],
        "url": "https://lemonergy.com/learn/glossary/phase-transition/",
        "mentions": []
      }
    },
    {
      "id": "term:manganese",
      "type": "Term",
      "label": "Manganese",
      "properties": {
        "id": "manganese",
        "name": "Manganese",
        "aka": [
          "manganese sulfate",
          "high-purity manganese sulfate",
          "HPMSM"
        ],
        "section": "topic-sustainability",
        "definition": "A cheap, abundant metal used in NMC, LMO and LMFP positive electrodes and in alkaline cells. Ore comes mostly from South Africa, Gabon and Australia, but about 95 % of battery-grade high-purity manganese sulfate was refined in China in 2024, which puts manganese on critical-raw-material lists despite plentiful reserves.",
        "related": [
          "nmc",
          "lmo",
          "lmfp",
          "critical-raw-materials",
          "cobalt",
          "nickel-sulfate"
        ],
        "url": "https://lemonergy.com/learn/glossary/manganese/",
        "mentions": []
      }
    }
  ]
}