{
  "node": {
    "id": "term:gas-generation",
    "type": "Term",
    "label": "Gas generation",
    "properties": {
      "id": "gas-generation",
      "name": "Gas generation",
      "aka": [
        "gassing"
      ],
      "section": "topic-aging",
      "definition": "Formation of gases — ethylene, hydrogen, carbon monoxide and carbon dioxide — by electrolyte decomposition, mostly during formation and later under high voltage or temperature. In a pouch cell it shows as swelling; in a can it raises pressure until the vent opens.",
      "related": [
        "swelling",
        "degassing",
        "electrolyte-decomposition",
        "vent",
        "formation"
      ],
      "lesson": "fundamentals/battery-aging/#gas",
      "url": "https://lemonergy.com/learn/glossary/gas-generation/",
      "mentions": [
        "electrolyte",
        "pouch-cell"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:1514",
      "source": "term:gas-generation",
      "target": "topic:topic-aging",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:1515",
      "source": "term:gas-generation",
      "target": "term:swelling",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1516",
      "source": "term:gas-generation",
      "target": "term:degassing",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1517",
      "source": "term:gas-generation",
      "target": "term:electrolyte-decomposition",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1518",
      "source": "term:gas-generation",
      "target": "term:vent",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1519",
      "source": "term:gas-generation",
      "target": "term:formation",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/gas-generation/electrolyte",
      "source": "term:gas-generation",
      "target": "term:electrolyte",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/gas-generation/pouch-cell",
      "source": "term:gas-generation",
      "target": "term:pouch-cell",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    },
    {
      "id": "edge:1522",
      "source": "term:gas-generation",
      "target": "lesson:fundamentals/battery-aging/",
      "type": "explainedIn",
      "properties": {
        "sourceFile": "terms.json",
        "url": "https://lemonergy.com/learn/fundamentals/battery-aging/#gas"
      }
    },
    {
      "id": "edge:1523",
      "source": "term:gas-generation",
      "target": "reference:edge-degradation",
      "type": "cites",
      "properties": {
        "sourceFile": "wiki-references.json",
        "scope": "direct technical reference"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-aging",
      "type": "Topic",
      "label": "Aging and degradation",
      "properties": {
        "id": "topic-aging",
        "name": "Aging and degradation",
        "lede": "Why a cell loses capacity and gains resistance, and the mechanisms behind it.",
        "context": "Separate mechanisms, observations and fitted models.",
        "example": "Capacity loss and resistance rise can have different causes; a film-growth curve cannot identify both.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/battery-aging/",
        "lesson_label": "Open aging"
      }
    },
    {
      "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:degassing",
      "type": "Term",
      "label": "Degassing",
      "properties": {
        "id": "degassing",
        "name": "Degassing",
        "section": "topic-manufacturing",
        "definition": "Removing the gas a cell releases during formation. A pouch cell’s extra gas pocket is opened in a dry atmosphere, emptied and sealed off; large prismatic cells often vent through their fill opening before final sealing.",
        "related": [
          "formation",
          "gas-generation",
          "pouch-cell",
          "cell-finishing"
        ],
        "lesson": "fundamentals/cell-production/#finishing",
        "url": "https://lemonergy.com/learn/glossary/degassing/",
        "mentions": []
      }
    },
    {
      "id": "term:electrolyte-decomposition",
      "type": "Term",
      "label": "Electrolyte decomposition",
      "properties": {
        "id": "electrolyte-decomposition",
        "name": "Electrolyte decomposition",
        "section": "topic-aging",
        "definition": "Reduction of the electrolyte at the negative electrode and oxidation at the positive, outside its stability window. A little is useful — it builds the SEI — but continued decomposition consumes lithium, dries the cell and makes gas.",
        "related": [
          "sei",
          "cei",
          "electrochemical-stability-window",
          "gas-generation",
          "electrolyte-dry-out"
        ],
        "url": "https://lemonergy.com/learn/glossary/electrolyte-decomposition/",
        "mentions": [
          "electrode",
          "negative-electrode",
          "electrolyte",
          "oxidation",
          "reduction"
        ]
      }
    },
    {
      "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:formation",
      "type": "Term",
      "label": "Formation",
      "properties": {
        "id": "formation",
        "name": "Formation",
        "section": "topic-manufacturing",
        "definition": "The first controlled charge and discharge cycles of a newly assembled cell, during which the SEI forms. It is part of cell production, before aging and grading.",
        "related": [
          "sei",
          "degassing",
          "aging-step",
          "first-cycle-loss",
          "cell-finishing"
        ],
        "lesson": "fundamentals/cell-production/#finishing",
        "example": {
          "title": "Distinguish first finishing cycles",
          "text": "Initial controlled cycles are a cell-finishing operation; their purpose and observations differ from later customer charging."
        },
        "url": "https://lemonergy.com/learn/glossary/formation/",
        "mentions": [
          "cell-production"
        ]
      }
    },
    {
      "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"
        ]
      }
    },
    {
      "id": "term:pouch-cell",
      "type": "Term",
      "label": "Pouch cell",
      "properties": {
        "id": "pouch-cell",
        "name": "Pouch cell",
        "aka": [
          "lithium polymer cell",
          "LiPo"
        ],
        "section": "topic-chemistries",
        "definition": "A cell sealed in a flexible bag of aluminium laminated with plastic, holding stacked electrode sheets in larger cells or a flattened wound roll in many small ones. It is light and easy to cool, but needs outside support and can visibly swell if gas forms inside.",
        "related": [
          "pouch-foil",
          "stacking",
          "swelling",
          "degassing",
          "prismatic-cell"
        ],
        "lesson": "fundamentals/cell-production/#formats",
        "example": {
          "title": "Include mechanical support",
          "text": "A pouch encloses layered electrodes. Support provided by the module is part of the complete design, separate from the active layers."
        },
        "url": "https://lemonergy.com/learn/glossary/pouch-cell/",
        "mentions": [
          "electrode"
        ]
      }
    },
    {
      "id": "lesson:fundamentals/battery-aging/",
      "type": "Lesson",
      "label": "Lesson 4 · Battery aging",
      "properties": {
        "url": "https://lemonergy.com/learn/fundamentals/battery-aging/"
      }
    },
    {
      "id": "reference:edge-degradation",
      "type": "Reference",
      "label": "Lithium ion battery degradation: what you need to know",
      "properties": {
        "title": "Lithium ion battery degradation: what you need to know",
        "publisher": "Physical Chemistry Chemical Physics",
        "url": "https://doi.org/10.1039/D1CP00359C",
        "type": "Review article",
        "scope": "Degradation mechanisms, modes, operational effects and their interactions.",
        "year": 2021,
        "accessed": "2026-10-27"
      }
    }
  ]
}