{
  "node": {
    "id": "term:off-gas",
    "type": "Term",
    "label": "Off-gas",
    "properties": {
      "id": "off-gas",
      "name": "Off-gas",
      "aka": [
        "vent gas"
      ],
      "section": "topic-safety",
      "definition": "The mixture released when a cell vents: electrolyte vapour, hydrogen, carbon monoxide, carbon dioxide and hydrocarbons, with hydrogen fluoride. It is flammable and toxic, and gas sensors detect it before smoke or heat in a storage container.",
      "related": [
        "venting",
        "hydrofluoric-acid",
        "gas-detection",
        "thermal-runaway"
      ],
      "url": "https://lemonergy.com/learn/glossary/off-gas/",
      "mentions": [
        "electrolyte"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:1680",
      "source": "term:off-gas",
      "target": "topic:topic-safety",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:1681",
      "source": "term:off-gas",
      "target": "term:venting",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1682",
      "source": "term:off-gas",
      "target": "term:hydrofluoric-acid",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1683",
      "source": "term:off-gas",
      "target": "term:gas-detection",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1684",
      "source": "term:off-gas",
      "target": "term:thermal-runaway",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/off-gas/electrolyte",
      "source": "term:off-gas",
      "target": "term:electrolyte",
      "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:venting",
      "type": "Term",
      "label": "Venting",
      "properties": {
        "id": "venting",
        "name": "Venting",
        "section": "topic-safety",
        "definition": "The controlled release of gas and vapour from a cell whose internal pressure has risen too far, through a vent designed to open before the case bursts. The vented gas is flammable and toxic, so packs route it away from occupants.",
        "related": [
          "vent",
          "gas-generation",
          "thermal-runaway",
          "off-gas"
        ],
        "url": "https://lemonergy.com/learn/glossary/venting/",
        "mentions": []
      }
    },
    {
      "id": "term:hydrofluoric-acid",
      "type": "Term",
      "label": "Hydrofluoric acid",
      "properties": {
        "id": "hydrofluoric-acid",
        "name": "Hydrofluoric acid",
        "abbr": "HF",
        "section": "topic-safety",
        "definition": "Formed when LiPF₆ electrolyte meets water, or when a fluorinated cell burns. Inside a cell traces of it attack the positive electrode and SEI; in a fire it is the most dangerous component of the vented gas.",
        "related": [
          "lithium-salt",
          "off-gas",
          "transition-metal-dissolution",
          "dry-room"
        ],
        "url": "https://lemonergy.com/learn/glossary/hydrofluoric-acid/",
        "mentions": [
          "electrode",
          "positive-electrode",
          "electrolyte",
          "sei",
          "lipf6"
        ]
      }
    },
    {
      "id": "term:gas-detection",
      "type": "Term",
      "label": "Gas detection",
      "properties": {
        "id": "gas-detection",
        "name": "Gas detection",
        "aka": [
          "off-gas detection"
        ],
        "section": "topic-safety",
        "definition": "Sensors in a pack or storage container that detect electrolyte vapour or hydrogen released before thermal runaway. Off-gas appears minutes before heat and smoke, which makes it the earliest practical warning.",
        "related": [
          "off-gas",
          "venting",
          "fire-suppression",
          "bms",
          "early-thermal-runaway-detection"
        ],
        "url": "https://lemonergy.com/learn/glossary/gas-detection/",
        "mentions": [
          "electrolyte",
          "thermal-runaway"
        ]
      }
    },
    {
      "id": "term:thermal-runaway",
      "type": "Term",
      "label": "Thermal runaway",
      "properties": {
        "id": "thermal-runaway",
        "name": "Thermal runaway",
        "section": "topic-safety",
        "definition": "Self-accelerating heating in a cell: heat speeds up reactions that release more heat, until the cell vents, catches fire or ruptures. An internal short, overcharge or external heating can trigger it.",
        "related": [
          "onset-temperature",
          "thermal-propagation",
          "venting",
          "separator-shutdown",
          "thermal-runaway-energy",
          "exothermic"
        ],
        "lesson": "fundamentals/cell-anatomy/#short-circuit",
        "url": "https://lemonergy.com/learn/glossary/thermal-runaway/",
        "mentions": [
          "overcharge"
        ]
      }
    },
    {
      "id": "term:electrolyte",
      "type": "Term",
      "label": "Electrolyte",
      "properties": {
        "id": "electrolyte",
        "name": "Electrolyte",
        "section": "topic-electrolytes",
        "definition": "The ion-conducting medium between the electrodes. In a liquid-electrolyte cell it fills the pores of both electrodes and the separator, so it is not a separate structural layer.",
        "related": [
          "lithium-salt",
          "carbonate-solvent",
          "electrolyte-additive",
          "ionic-conductivity",
          "solid-electrolyte",
          "ionic-liquid-electrolyte"
        ],
        "lesson": "fundamentals/cell-architecture/#electrolyte",
        "example": {
          "title": "Ions and electrons",
          "text": "Electrolyte carries ions between electrodes; the external circuit carries electrons. The two paths serve different roles."
        },
        "url": "https://lemonergy.com/learn/glossary/electrolyte/",
        "mentions": [
          "separator"
        ]
      }
    }
  ]
}