{
  "node": {
    "id": "term:centre-pin",
    "type": "Term",
    "label": "Centre pin",
    "properties": {
      "id": "centre-pin",
      "name": "Centre pin",
      "aka": [
        "center pin",
        "core pin"
      ],
      "section": "topic-components",
      "definition": "A hollow metal tube placed in the core of a cylindrical cell’s jelly roll, in the hole left by the winding mandrel. It stops the winding collapsing inward and keeps a clear channel for gas to reach the vent during failure; X-ray studies of 18650 cells in thermal runaway showed unsupported cores collapsing after venting.",
      "related": [
        "cylindrical-cell",
        "jelly-roll",
        "vent",
        "thermal-runaway",
        "winding",
        "internal-short-circuit"
      ],
      "url": "https://lemonergy.com/learn/glossary/centre-pin/",
      "mentions": []
    }
  },
  "edges": [
    {
      "id": "edge:5706",
      "source": "term:centre-pin",
      "target": "topic:topic-components",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:5707",
      "source": "term:centre-pin",
      "target": "term:cylindrical-cell",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5708",
      "source": "term:centre-pin",
      "target": "term:jelly-roll",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5709",
      "source": "term:centre-pin",
      "target": "term:vent",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5710",
      "source": "term:centre-pin",
      "target": "term:thermal-runaway",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5711",
      "source": "term:centre-pin",
      "target": "term:winding",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5712",
      "source": "term:centre-pin",
      "target": "term:internal-short-circuit",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-components",
      "type": "Topic",
      "label": "Cell components and electrode materials",
      "properties": {
        "id": "topic-components",
        "name": "Cell components and electrode materials",
        "lede": "What a cell is physically made of — active materials, binders, additives, foils and tabs — and how its electrodes are put together.",
        "context": "Connect each material with its function.",
        "example": "Electrons travel through additive, foil and tab; ions use electrolyte and separator pathways.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/cell-anatomy/",
        "lesson_label": "Open cell anatomy"
      }
    },
    {
      "id": "term:cylindrical-cell",
      "type": "Term",
      "label": "Cylindrical cell",
      "properties": {
        "id": "cylindrical-cell",
        "name": "Cylindrical cell",
        "aka": [
          "18650",
          "21700",
          "4680"
        ],
        "section": "topic-chemistries",
        "definition": "A cell made by winding the electrodes into a jelly roll and sealing it in a round metal can. Sizes are named by their dimensions: a 21700 cell is 21 mm across and 70 mm long.",
        "related": [
          "jelly-roll",
          "can",
          "tabless-design",
          "prismatic-cell",
          "pouch-cell",
          "centre-pin"
        ],
        "lesson": "fundamentals/cell-production/#formats",
        "example": {
          "title": "Shape versus ratings",
          "text": "A cylindrical shape does not supply the model’s capacity, resistance or voltage limits; those belong to the actual cell."
        },
        "url": "https://lemonergy.com/learn/glossary/cylindrical-cell/",
        "mentions": [
          "winding"
        ]
      }
    },
    {
      "id": "term:jelly-roll",
      "type": "Term",
      "label": "Jelly roll",
      "properties": {
        "id": "jelly-roll",
        "name": "Jelly roll",
        "section": "topic-components",
        "definition": "Electrodes and separators wound together into a spiral. It is the inside of a cylindrical cell and of many prismatic cells; large pouch cells usually use stacked sheets instead.",
        "related": [
          "winding",
          "cylindrical-cell",
          "prismatic-cell",
          "stacking"
        ],
        "lesson": "fundamentals/cell-architecture/#whole-cell",
        "example": {
          "title": "Unroll the geometry",
          "text": "A wound assembly contains long electrode and separator strips; the cylindrical exterior does not make its electrodes solid cylinders."
        },
        "url": "https://lemonergy.com/learn/glossary/jelly-roll/",
        "mentions": []
      }
    },
    {
      "id": "term:vent",
      "type": "Term",
      "label": "Vent",
      "properties": {
        "id": "vent",
        "name": "Vent",
        "aka": [
          "burst disc",
          "rupture disc"
        ],
        "section": "topic-safety",
        "definition": "A scored area or a membrane in the cell can that opens at a set pressure, around ten to thirty bar for a cylindrical cell, so that gas escapes in a chosen direction instead of the case splitting at random.",
        "related": [
          "venting",
          "can",
          "current-interrupt-device"
        ],
        "url": "https://lemonergy.com/learn/glossary/vent/",
        "mentions": [
          "cylindrical-cell"
        ]
      }
    },
    {
      "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:winding",
      "type": "Term",
      "label": "Winding",
      "properties": {
        "id": "winding",
        "name": "Winding",
        "section": "topic-manufacturing",
        "definition": "Rolling the two electrode strips and two separator strips together around a mandrel into a jelly roll. It is fast and well understood, and it produces the round roll of a cylindrical cell or the flattened roll of many prismatic cells.",
        "related": [
          "jelly-roll",
          "stacking",
          "cylindrical-cell",
          "prismatic-cell"
        ],
        "lesson": "fundamentals/cell-production/#assembly",
        "url": "https://lemonergy.com/learn/glossary/winding/",
        "mentions": [
          "electrode",
          "separator"
        ]
      }
    },
    {
      "id": "term:internal-short-circuit",
      "type": "Term",
      "label": "Internal short circuit",
      "properties": {
        "id": "internal-short-circuit",
        "name": "Internal short circuit",
        "abbr": "ISC",
        "section": "topic-safety",
        "definition": "An unintended electronic path between the electrodes inside a cell — through a metal particle, a burr, a damaged separator or lithium deposits. It discharges the cell internally and turns its energy into local heat.",
        "related": [
          "thermal-runaway",
          "dendrite",
          "separator",
          "external-short-circuit",
          "self-discharge",
          "internal-short-trigger-device"
        ],
        "lesson": "fundamentals/cell-anatomy/#short-circuit",
        "url": "https://lemonergy.com/learn/glossary/internal-short-circuit/",
        "mentions": [
          "electronic-path",
          "burr",
          "metal-particle-contamination"
        ]
      }
    }
  ]
}