{
  "node": {
    "id": "term:helium-leak-test",
    "type": "Term",
    "label": "Helium leak test",
    "properties": {
      "id": "helium-leak-test",
      "name": "Helium leak test",
      "aka": [
        "leak test",
        "helium bombing",
        "tracer-gas leak test"
      ],
      "section": "topic-testing",
      "definition": "Checking that a cell can, pouch or cooling plate is sealed by detecting, with a mass spectrometer, helium escaping from it into a vacuum chamber. Helium goes in before sealing or is forced in under pressure afterwards; cells are typically screened at around 10⁻⁶ mbar·L/s, tight enough to keep moisture out and electrolyte in for the cell’s life.",
      "unit": "mbar·L/s",
      "related": [
        "can",
        "pouch-cell",
        "moisture-content",
        "end-of-line-testing",
        "cooling-plate"
      ],
      "url": "https://lemonergy.com/learn/glossary/helium-leak-test/",
      "mentions": [
        "electrolyte"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:5464",
      "source": "term:helium-leak-test",
      "target": "topic:topic-testing",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:5465",
      "source": "term:helium-leak-test",
      "target": "term:can",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5466",
      "source": "term:helium-leak-test",
      "target": "term:pouch-cell",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5467",
      "source": "term:helium-leak-test",
      "target": "term:moisture-content",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5468",
      "source": "term:helium-leak-test",
      "target": "term:end-of-line-testing",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5469",
      "source": "term:helium-leak-test",
      "target": "term:cooling-plate",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/helium-leak-test/electrolyte",
      "source": "term:helium-leak-test",
      "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-testing",
      "type": "Topic",
      "label": "Testing methods",
      "properties": {
        "id": "topic-testing",
        "name": "Testing methods",
        "lede": "The measurements and test procedures that characterise a cell or pack, from capacity and pulse tests to abuse and environmental tests.",
        "context": "Record specimen, state, instrument, temperature and timing.",
        "example": "Resistance immediately after a current step can differ from a ten-second value because slower polarization contributes.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/capacity-and-c-rate/",
        "lesson_label": "Open capacity measurements"
      }
    },
    {
      "id": "term:can",
      "type": "Term",
      "label": "Can",
      "properties": {
        "id": "can",
        "name": "Can",
        "aka": [
          "casing",
          "housing"
        ],
        "section": "topic-components",
        "definition": "The rigid metal case of a cylindrical or prismatic cell, usually nickel-plated steel or aluminium. It holds the stack under pressure, contains the electrolyte and, in a cylindrical cell, doubles as the negative terminal.",
        "related": [
          "cylindrical-cell",
          "prismatic-cell",
          "pouch-foil",
          "vent",
          "helium-leak-test"
        ],
        "url": "https://lemonergy.com/learn/glossary/can/",
        "mentions": [
          "electrolyte"
        ]
      }
    },
    {
      "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": "term:moisture-content",
      "type": "Term",
      "label": "Moisture content",
      "properties": {
        "id": "moisture-content",
        "name": "Moisture content",
        "aka": [
          "Karl Fischer titration"
        ],
        "section": "topic-manufacturing",
        "definition": "The water left in electrodes, separator and electrolyte, measured by Karl Fischer titration and specified in the low hundreds of parts per million or below. Water forms HF with the salt, which attacks the positive electrode and the SEI.",
        "unit": "ppm",
        "related": [
          "vacuum-drying",
          "dry-room",
          "hydrofluoric-acid"
        ],
        "url": "https://lemonergy.com/learn/glossary/moisture-content/",
        "mentions": [
          "electrode",
          "positive-electrode",
          "separator",
          "electrolyte",
          "sei"
        ]
      }
    },
    {
      "id": "term:end-of-line-testing",
      "type": "Term",
      "label": "End-of-line testing",
      "properties": {
        "id": "end-of-line-testing",
        "name": "End-of-line testing",
        "abbr": "EOL test",
        "section": "topic-manufacturing",
        "definition": "The final measurements on every finished cell — capacity, internal resistance and open-circuit voltage — used to reject faulty cells and sort good ones into matched grades.",
        "related": [
          "grading",
          "capacity-test",
          "k-value",
          "cell-finishing"
        ],
        "lesson": "fundamentals/cell-production/#finishing",
        "url": "https://lemonergy.com/learn/glossary/end-of-line-testing/",
        "mentions": [
          "internal-resistance",
          "open-circuit-voltage"
        ]
      }
    },
    {
      "id": "term:cooling-plate",
      "type": "Term",
      "label": "Cooling plate",
      "properties": {
        "id": "cooling-plate",
        "name": "Cooling plate",
        "aka": [
          "cold plate"
        ],
        "section": "topic-thermal",
        "definition": "A flat aluminium channel assembly under or between the cells through which coolant, usually a water–glycol mix, is pumped. Heat crosses from cell to plate through a thermal interface material; the plate also sets the pack’s temperature uniformity.",
        "related": [
          "thermal-management",
          "thermal-interface-material",
          "immersion-cooling"
        ],
        "url": "https://lemonergy.com/learn/glossary/cooling-plate/",
        "mentions": [
          "thermal-gradient",
          "coolant"
        ]
      }
    },
    {
      "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"
        ]
      }
    }
  ]
}