{
  "node": {
    "id": "term:aerogel",
    "type": "Term",
    "label": "Aerogel",
    "properties": {
      "id": "aerogel",
      "name": "Aerogel",
      "aka": [
        "silica aerogel",
        "aerogel sheet"
      ],
      "section": "topic-safety",
      "definition": "A solid foam, usually of silica, that is mostly air held in nanometre-scale pores, giving a thermal conductivity of only about 0.015–0.02 W/(m·K). Sheets a millimetre or two thick between cells slow heat transfer during a thermal event, though they must keep their insulation under the compression of swelling cells.",
      "related": [
        "thermal-barrier",
        "thermal-propagation",
        "compression-pad",
        "intumescent-material"
      ],
      "url": "https://lemonergy.com/learn/glossary/aerogel/",
      "mentions": [
        "swelling",
        "thermal-conductivity"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:6655",
      "source": "term:aerogel",
      "target": "topic:topic-safety",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:6656",
      "source": "term:aerogel",
      "target": "term:thermal-barrier",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6657",
      "source": "term:aerogel",
      "target": "term:thermal-propagation",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6658",
      "source": "term:aerogel",
      "target": "term:compression-pad",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6659",
      "source": "term:aerogel",
      "target": "term:intumescent-material",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/aerogel/swelling",
      "source": "term:aerogel",
      "target": "term:swelling",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/aerogel/thermal-conductivity",
      "source": "term:aerogel",
      "target": "term:thermal-conductivity",
      "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-safety",
      "type": "Topic",
      "label": "Safety and abuse",
      "properties": {
        "id": "topic-safety",
        "name": "Safety and abuse",
        "lede": "How cells fail dangerously, how that is tested, and what is built in to stop it.",
        "context": "Connect mechanisms with appropriate test evidence.",
        "example": "A low normal-load temperature does not demonstrate thermal-runaway containment.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/battery-aging/",
        "lesson_label": "Open degradation mechanisms"
      }
    },
    {
      "id": "term:thermal-barrier",
      "type": "Term",
      "label": "Thermal barrier",
      "properties": {
        "id": "thermal-barrier",
        "name": "Thermal barrier",
        "aka": [
          "fire-resistant pad",
          "mica sheet"
        ],
        "section": "topic-safety",
        "definition": "An insulating sheet — aerogel, mica, ceramic fibre or intumescent material — placed between cells or modules to slow heat transfer during a thermal event and buy time for occupants to leave.",
        "related": [
          "thermal-propagation",
          "compression-pad",
          "module"
        ],
        "url": "https://lemonergy.com/learn/glossary/thermal-barrier/",
        "mentions": [
          "aerogel",
          "intumescent-material"
        ]
      }
    },
    {
      "id": "term:thermal-propagation",
      "type": "Term",
      "label": "Thermal propagation",
      "properties": {
        "id": "thermal-propagation",
        "name": "Thermal propagation",
        "section": "topic-safety",
        "definition": "Thermal runaway spreading from one cell to its neighbours through conducted heat, hot gas and flame. Pack designs are judged by whether, and how slowly, a single failing cell takes the rest with it.",
        "related": [
          "thermal-runaway",
          "thermal-barrier",
          "venting",
          "module",
          "propagation-test"
        ],
        "url": "https://lemonergy.com/learn/glossary/thermal-propagation/",
        "mentions": []
      }
    },
    {
      "id": "term:compression-pad",
      "type": "Term",
      "label": "Compression pad",
      "properties": {
        "id": "compression-pad",
        "name": "Compression pad",
        "aka": [
          "foam pad",
          "swelling pad"
        ],
        "section": "topic-pack",
        "definition": "A foam sheet between pouch or prismatic cells that keeps a defined pressure on them as they breathe on charge and swell with age. It also provides some thermal separation between neighbours.",
        "related": [
          "swelling",
          "stack-pressure",
          "thermal-barrier",
          "pouch-cell"
        ],
        "url": "https://lemonergy.com/learn/glossary/compression-pad/",
        "mentions": []
      }
    },
    {
      "id": "term:intumescent-material",
      "type": "Term",
      "label": "Intumescent material",
      "properties": {
        "id": "intumescent-material",
        "name": "Intumescent material",
        "aka": [
          "intumescent coating",
          "intumescent pad"
        ],
        "section": "topic-safety",
        "definition": "A material that swells to many times its original thickness when heated, forming a porous char that insulates whatever lies beneath. Applied as coatings on pack lids or as pads between cells, it stays thin in normal service and expands only during a thermal event, which suits the tight spaces inside a battery.",
        "related": [
          "thermal-barrier",
          "thermal-propagation",
          "aerogel",
          "enclosure"
        ],
        "url": "https://lemonergy.com/learn/glossary/intumescent-material/",
        "mentions": []
      }
    },
    {
      "id": "term:swelling",
      "type": "Term",
      "label": "Swelling",
      "properties": {
        "id": "swelling",
        "name": "Swelling",
        "section": "topic-aging",
        "definition": "Growth in a cell’s thickness, reversibly as the electrodes expand on charge and irreversibly as gas and SEI accumulate. Packs allow for it with compression pads, and a sudden swell in service is a warning sign.",
        "related": [
          "gas-generation",
          "pouch-cell",
          "silicon-anode",
          "stack-pressure",
          "compression-pad",
          "swelling-test"
        ],
        "url": "https://lemonergy.com/learn/glossary/swelling/",
        "mentions": [
          "sei"
        ]
      }
    },
    {
      "id": "term:thermal-conductivity",
      "type": "Term",
      "label": "Thermal conductivity",
      "properties": {
        "id": "thermal-conductivity",
        "name": "Thermal conductivity",
        "abbr": "k",
        "aka": [
          "λ",
          "through-plane conductivity",
          "in-plane conductivity"
        ],
        "section": "topic-thermal",
        "definition": "How readily a material conducts heat: the heat flux per unit temperature gradient. Cells are strongly anisotropic — around 25–45 W/(m·K) in-plane, along the metal foils, but below 1 W/(m·K) through-plane, across separators and coatings — so the side a cell is cooled from decides how hot its core runs.",
        "formula": "q″ = −k·dT/dx",
        "unit": "W/(m·K)",
        "related": [
          "thermal-resistance",
          "thermal-diffusivity",
          "thermal-characterisation",
          "thermal-interface-material",
          "biot-number",
          "thermal-model"
        ],
        "example": {
          "title": "Calculate a slab heat flow",
          "text": "An illustrative 2 mm layer with k = 1 W/(m·K), area 0.01 m² and a 10 K temperature difference transfers 50 W in steady one-dimensional conduction. Contact resistances and edge losses are omitted."
        },
        "url": "https://lemonergy.com/learn/glossary/thermal-conductivity/",
        "mentions": [
          "heat-flux",
          "thermal-gradient"
        ]
      }
    }
  ]
}