{
  "node": {
    "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": []
    }
  },
  "edges": [
    {
      "id": "edge:1993",
      "source": "term:phase-transition",
      "target": "topic:topic-electrochemistry",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:1994",
      "source": "term:phase-transition",
      "target": "term:voltage-plateau",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1995",
      "source": "term:phase-transition",
      "target": "term:differential-voltage-analysis",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1996",
      "source": "term:phase-transition",
      "target": "term:lfp",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1997",
      "source": "term:phase-transition",
      "target": "term:graphite",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1998",
      "source": "term:phase-transition",
      "target": "term:structural-degradation",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-electrochemistry",
      "type": "Topic",
      "label": "Electrochemistry fundamentals",
      "properties": {
        "id": "topic-electrochemistry",
        "name": "Electrochemistry fundamentals",
        "lede": "The reactions and potentials that make a cell a battery.",
        "context": "Connect reaction sites and transport paths.",
        "example": "A circuit can predict terminal voltage while leaving electrode potentials and reaction kinetics unresolved.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/cell-anatomy/",
        "lesson_label": "Open cell anatomy"
      }
    },
    {
      "id": "term:voltage-plateau",
      "type": "Term",
      "label": "Voltage plateau",
      "properties": {
        "id": "voltage-plateau",
        "name": "Voltage plateau",
        "section": "topic-charging",
        "definition": "A stretch of the voltage curve where voltage barely changes while charge passes, because the electrode is moving between two phases at a fixed potential. LFP has one long plateau; graphite shows several small ones.",
        "related": [
          "discharge-curve",
          "lfp",
          "phase-transition",
          "ocv-soc-curve"
        ],
        "url": "https://lemonergy.com/learn/glossary/voltage-plateau/",
        "mentions": [
          "electrode",
          "graphite"
        ]
      }
    },
    {
      "id": "term:differential-voltage-analysis",
      "type": "Term",
      "label": "Differential voltage analysis",
      "properties": {
        "id": "differential-voltage-analysis",
        "name": "Differential voltage analysis",
        "abbr": "DVA",
        "aka": [
          "dV/dQ"
        ],
        "section": "topic-state",
        "definition": "Plotting the derivative of voltage with respect to charge during a slow cycle. Its peaks mark electrode phase transitions, and how they shift between cycles separates lithium inventory loss from active-material loss without opening the cell.",
        "formula": "dV/dQ vs Q",
        "related": [
          "incremental-capacity-analysis",
          "loss-of-lithium-inventory",
          "loss-of-active-material",
          "phase-transition"
        ],
        "example": {
          "title": "Interpret a local slope",
          "text": "If voltage changes by 0.020 V over 0.10 Ah in a slowly measured region, the local slope is approximately 0.20 V/Ah. Comparing curves requires consistent current, temperature, sampling and preprocessing."
        },
        "url": "https://lemonergy.com/learn/glossary/differential-voltage-analysis/",
        "mentions": [
          "electrode"
        ]
      }
    },
    {
      "id": "term:lfp",
      "type": "Term",
      "label": "LFP",
      "properties": {
        "id": "lfp",
        "name": "LFP",
        "aka": [
          "lithium iron phosphate",
          "LiFePO₄"
        ],
        "section": "topic-chemistries",
        "definition": "A positive electrode material, LiFePO₄, giving cells a nominal voltage around 3.2 V, long cycle life and good thermal stability, but less energy per kilogram than nickel-rich oxides. Its flat voltage curve makes state of charge hard to read from voltage alone.",
        "related": [
          "cathode-active-material",
          "nmc",
          "lmfp",
          "ocv-soc-curve",
          "cycle-life"
        ],
        "lesson": "fundamentals/cell-anatomy/#voltage",
        "example": {
          "title": "Chemistry is not the whole datasheet",
          "text": "Two LFP products can differ in format, loading, capacity and current limits. Their cathode family alone does not make them interchangeable."
        },
        "url": "https://lemonergy.com/learn/glossary/lfp/",
        "mentions": [
          "electrode",
          "positive-electrode",
          "nominal-voltage",
          "discharge-curve",
          "state-of-charge"
        ]
      }
    },
    {
      "id": "term:graphite",
      "type": "Term",
      "label": "Graphite",
      "properties": {
        "id": "graphite",
        "name": "Graphite",
        "section": "topic-components",
        "definition": "Layered carbon, the negative active material of nearly all lithium-ion cells. Lithium intercalates between its layers up to LiC₆, a theoretical 372 mAh/g, at a potential about 0.1 V above lithium metal.",
        "related": [
          "anode-active-material",
          "intercalation",
          "natural-graphite",
          "synthetic-graphite",
          "lithium-plating"
        ],
        "lesson": "fundamentals/cell-anatomy/#components",
        "example": {
          "title": "Compare matching mass bases",
          "text": "A graphite value per gram of active material cannot be directly compared with a value including binder, additive and foil."
        },
        "url": "https://lemonergy.com/learn/glossary/graphite/",
        "mentions": [
          "milliampere-hour",
          "active-material"
        ]
      }
    },
    {
      "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"
        ]
      }
    }
  ]
}