{
  "node": {
    "id": "term:specific-surface-area",
    "type": "Term",
    "label": "Specific surface area",
    "properties": {
      "id": "specific-surface-area",
      "name": "Specific surface area",
      "abbr": "BET",
      "section": "topic-transport",
      "definition": "Surface per gram of a powder, measured by gas adsorption and quoted as the BET area in m²/g. More surface speeds the reaction but also grows more SEI, so graphite is engineered to a modest 1–3 m²/g.",
      "unit": "m²/g",
      "related": [
        "particle-size",
        "sei",
        "charge-transfer"
      ],
      "url": "https://lemonergy.com/learn/glossary/specific-surface-area/",
      "mentions": [
        "graphite"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:2113",
      "source": "term:specific-surface-area",
      "target": "topic:topic-transport",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:2114",
      "source": "term:specific-surface-area",
      "target": "term:particle-size",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:2115",
      "source": "term:specific-surface-area",
      "target": "term:sei",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:2116",
      "source": "term:specific-surface-area",
      "target": "term:charge-transfer",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/specific-surface-area/graphite",
      "source": "term:specific-surface-area",
      "target": "term:graphite",
      "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-transport",
      "type": "Topic",
      "label": "Transport and modelling",
      "properties": {
        "id": "topic-transport",
        "name": "Transport and modelling",
        "lede": "How ions move, and the equations and models that describe a cell.",
        "context": "Specify phase, direction and boundaries.",
        "example": "The same concentration difference across 10 μm gives ten times the gradient across 100 μm; at equal D, first-law flux magnitude is ten times greater.",
        "lesson_url": "https://lemonergy.com/learn/transport/ficks-first-law/",
        "lesson_label": "Open diffusion"
      }
    },
    {
      "id": "term:particle-size",
      "type": "Term",
      "label": "Particle size",
      "properties": {
        "id": "particle-size",
        "name": "Particle size",
        "aka": [
          "D50"
        ],
        "section": "topic-transport",
        "definition": "The diameter of active-material particles, usually quoted as D50, the median, in micrometres. Small particles shorten the solid diffusion path and favour power; large ones pack densely and favour energy and stability.",
        "unit": "µm",
        "related": [
          "solid-state-diffusion",
          "specific-surface-area",
          "rate-capability",
          "single-crystal"
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        "url": "https://lemonergy.com/learn/glossary/particle-size/",
        "mentions": [
          "diffusion"
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      }
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    {
      "id": "term:sei",
      "type": "Term",
      "label": "Solid–electrolyte interphase",
      "properties": {
        "id": "sei",
        "name": "Solid–electrolyte interphase",
        "abbr": "SEI",
        "section": "topic-aging",
        "definition": "A film of electrolyte reaction products on the negative-electrode particles — graphite, and also silicon or lithium metal. It protects the electrode from further reaction but grows slowly for the whole life of the cell, consuming cyclable lithium.",
        "related": [
          "passivation",
          "formation",
          "calendar-aging",
          "loss-of-lithium-inventory",
          "cei"
        ],
        "lesson": "fundamentals/battery-aging/#sei",
        "url": "https://lemonergy.com/learn/glossary/sei/",
        "mentions": [
          "electrode",
          "graphite",
          "electrolyte"
        ]
      }
    },
    {
      "id": "term:charge-transfer",
      "type": "Term",
      "label": "Charge transfer",
      "properties": {
        "id": "charge-transfer",
        "name": "Charge transfer",
        "section": "topic-electrochemistry",
        "definition": "The step in which an electron crosses the interface between electrode and electrolyte as an ion is inserted or removed. Its resistance appears as a semicircle in impedance spectra and grows as films thicken and the cell cools.",
        "related": [
          "butler-volmer",
          "double-layer",
          "electrochemical-impedance-spectroscopy",
          "overpotential",
          "solvation"
        ],
        "url": "https://lemonergy.com/learn/glossary/charge-transfer/",
        "mentions": [
          "impedance",
          "electrode",
          "electrolyte"
        ]
      }
    },
    {
      "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"
        ]
      }
    }
  ]
}