{
  "node": {
    "id": "term:onset-temperature",
    "type": "Term",
    "label": "Onset temperature",
    "properties": {
      "id": "onset-temperature",
      "name": "Onset temperature",
      "aka": [
        "self-heating onset"
      ],
      "section": "topic-safety",
      "definition": "The temperature at which a cell begins to generate heat by itself, as the SEI starts to decompose, typically 80–120 °C. Measured in an accelerating rate calorimeter, it marks the start of the path to thermal runaway, not the runaway itself.",
      "unit": "°C",
      "related": [
        "thermal-runaway",
        "accelerating-rate-calorimetry",
        "sei",
        "separator-shutdown",
        "critical-self-heating-temperature"
      ],
      "url": "https://lemonergy.com/learn/glossary/onset-temperature/",
      "mentions": []
    }
  },
  "edges": [
    {
      "id": "edge:1633",
      "source": "term:onset-temperature",
      "target": "topic:topic-safety",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:1634",
      "source": "term:onset-temperature",
      "target": "term:thermal-runaway",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1635",
      "source": "term:onset-temperature",
      "target": "term:accelerating-rate-calorimetry",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1636",
      "source": "term:onset-temperature",
      "target": "term:sei",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1637",
      "source": "term:onset-temperature",
      "target": "term:separator-shutdown",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
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      "id": "edge:1638",
      "source": "term:onset-temperature",
      "target": "term:critical-self-heating-temperature",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    }
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    {
      "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"
      }
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    {
      "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"
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        "lesson": "fundamentals/cell-anatomy/#short-circuit",
        "url": "https://lemonergy.com/learn/glossary/thermal-runaway/",
        "mentions": [
          "overcharge"
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      }
    },
    {
      "id": "term:accelerating-rate-calorimetry",
      "type": "Term",
      "label": "Accelerating rate calorimetry",
      "properties": {
        "id": "accelerating-rate-calorimetry",
        "name": "Accelerating rate calorimetry",
        "abbr": "ARC",
        "section": "topic-safety",
        "definition": "A test in which a cell sits in an adiabatic chamber that follows its temperature, so any self-heating is not lost to the surroundings. It measures the onset temperature, the self-heating rate and the temperature at which runaway becomes unstoppable.",
        "related": [
          "onset-temperature",
          "thermal-runaway",
          "differential-scanning-calorimetry"
        ],
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        "mentions": [
          "adiabatic-isothermal"
        ]
      }
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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"
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        "lesson": "fundamentals/battery-aging/#sei",
        "url": "https://lemonergy.com/learn/glossary/sei/",
        "mentions": [
          "electrode",
          "graphite",
          "electrolyte"
        ]
      }
    },
    {
      "id": "term:separator-shutdown",
      "type": "Term",
      "label": "Separator shutdown",
      "properties": {
        "id": "separator-shutdown",
        "name": "Separator shutdown",
        "section": "topic-safety",
        "definition": "A built-in safety feature of polyolefin separators: around 130 °C the polyethylene layer melts and closes its pores, stopping ion flow and the current with it. It helps only if the separator does not also shrink and let the electrodes touch, so shutdown behavior is not universal.",
        "related": [
          "separator",
          "ceramic-coated-separator",
          "thermal-runaway",
          "onset-temperature"
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        "lesson": "fundamentals/cell-architecture/#separator",
        "url": "https://lemonergy.com/learn/glossary/separator-shutdown/",
        "mentions": [
          "polyethylene-polypropylene"
        ]
      }
    },
    {
      "id": "term:critical-self-heating-temperature",
      "type": "Term",
      "label": "Critical self-heating temperature",
      "properties": {
        "id": "critical-self-heating-temperature",
        "name": "Critical self-heating temperature",
        "aka": [
          "critical temperature",
          "point of no return"
        ],
        "section": "topic-safety",
        "definition": "The highest temperature from which a cell, in its actual surroundings, can still cool back down; above it, self-heating outruns heat loss and thermal runaway follows even if the heat source is removed. Unlike the onset temperature, which is measured adiabatically, it depends on the installation: better cooling raises it, while larger cells and higher SOC lower it.",
        "related": [
          "onset-temperature",
          "thermal-runaway",
          "accelerating-rate-calorimetry",
          "thermal-management",
          "heat-generation"
        ],
        "url": "https://lemonergy.com/learn/glossary/critical-self-heating-temperature/",
        "mentions": [
          "state-of-charge"
        ]
      }
    }
  ]
}