{
  "node": {
    "id": "term:polyethylene-polypropylene",
    "type": "Term",
    "label": "Polyethylene and polypropylene",
    "properties": {
      "id": "polyethylene-polypropylene",
      "name": "Polyethylene and polypropylene",
      "abbr": "PE, PP",
      "aka": [
        "polyolefin",
        "polyethylene",
        "polypropylene"
      ],
      "section": "topic-electrolytes",
      "definition": "The two commodity polyolefins of a cell. Almost every separator is PE, PP or a layered combination: PE melts near 130 °C and closes its pores, while PP keeps its shape to about 165 °C. PP also forms the heat-sealing inner layer of pouch foil, and both appear in packs as insulating films and moulded parts.",
      "related": [
        "separator",
        "dry-wet-separator-process",
        "separator-shutdown",
        "pouch-foil",
        "ceramic-coated-separator"
      ],
      "url": "https://lemonergy.com/learn/glossary/polyethylene-polypropylene/",
      "mentions": []
    }
  },
  "edges": [
    {
      "id": "edge:5727",
      "source": "term:polyethylene-polypropylene",
      "target": "topic:topic-electrolytes",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:5728",
      "source": "term:polyethylene-polypropylene",
      "target": "term:separator",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5729",
      "source": "term:polyethylene-polypropylene",
      "target": "term:dry-wet-separator-process",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5730",
      "source": "term:polyethylene-polypropylene",
      "target": "term:separator-shutdown",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5731",
      "source": "term:polyethylene-polypropylene",
      "target": "term:pouch-foil",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5732",
      "source": "term:polyethylene-polypropylene",
      "target": "term:ceramic-coated-separator",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-electrolytes",
      "type": "Topic",
      "label": "Electrolytes and separators",
      "properties": {
        "id": "topic-electrolytes",
        "name": "Electrolytes and separators",
        "lede": "What sits between the electrodes: liquid, gel and solid electrolytes, their salts, solvents and additives, and the separator that keeps the electrodes apart.",
        "context": "Connect transport with electronic isolation.",
        "example": "Greater liquid uptake may improve wetting while changing mechanical behavior. Several properties define separator performance.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/cell-anatomy/",
        "lesson_label": "Open cell anatomy"
      }
    },
    {
      "id": "term:separator",
      "type": "Term",
      "label": "Separator",
      "properties": {
        "id": "separator",
        "name": "Separator",
        "section": "topic-electrolytes",
        "definition": "A porous, electronically insulating film between the electrodes. Electrons cannot cross it; ions move through the electrolyte in its pores.",
        "related": [
          "electrolyte",
          "ceramic-coated-separator",
          "separator-shutdown",
          "internal-short-circuit",
          "porosity"
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        "lesson": "fundamentals/cell-architecture/#separator",
        "example": {
          "title": "Different conduction paths",
          "text": "A separator prevents direct electronic contact while permitting ionic transport through its electrolyte-filled structure."
        },
        "url": "https://lemonergy.com/learn/glossary/separator/",
        "mentions": []
      }
    },
    {
      "id": "term:dry-wet-separator-process",
      "type": "Term",
      "label": "Dry- and wet-process separators",
      "properties": {
        "id": "dry-wet-separator-process",
        "name": "Dry- and wet-process separators",
        "aka": [
          "dry-process separator",
          "wet-process separator",
          "uniaxially stretched separator",
          "biaxially stretched separator"
        ],
        "section": "topic-electrolytes",
        "definition": "The two routes to a porous polyolefin film. The dry process extrudes polypropylene or a PP/PE/PP trilayer, anneals it and stretches it lengthwise so slit-like pores open, with no solvent. The wet process mixes polyethylene with paraffin oil, stretches the sheet both ways and extracts the oil, giving thinner, stronger, more uniform films — the usual choice for EV cells.",
        "related": [
          "separator",
          "polyethylene-polypropylene",
          "separator-shutdown",
          "ceramic-coated-separator",
          "porosity"
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        "url": "https://lemonergy.com/learn/glossary/dry-wet-separator-process/",
        "mentions": []
      }
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    {
      "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"
        ],
        "lesson": "fundamentals/cell-architecture/#separator",
        "url": "https://lemonergy.com/learn/glossary/separator-shutdown/",
        "mentions": [
          "polyethylene-polypropylene"
        ]
      }
    },
    {
      "id": "term:pouch-foil",
      "type": "Term",
      "label": "Pouch foil",
      "properties": {
        "id": "pouch-foil",
        "name": "Pouch foil",
        "aka": [
          "aluminium laminate"
        ],
        "section": "topic-components",
        "definition": "The flexible case of a pouch cell: a thin aluminium layer laminated between a polyamide outer film and a heat-sealable polypropylene inner film. It is light and cheap but offers no mechanical support and can swell.",
        "related": [
          "pouch-cell",
          "can",
          "swelling"
        ],
        "url": "https://lemonergy.com/learn/glossary/pouch-foil/",
        "mentions": [
          "polyethylene-polypropylene"
        ]
      }
    },
    {
      "id": "term:ceramic-coated-separator",
      "type": "Term",
      "label": "Ceramic-coated separator",
      "properties": {
        "id": "ceramic-coated-separator",
        "name": "Ceramic-coated separator",
        "section": "topic-electrolytes",
        "definition": "A polyolefin separator coated with a thin layer of alumina or boehmite particles. The ceramic raises the temperature at which the film shrinks, so the electrodes stay apart longer in a thermal event.",
        "related": [
          "separator",
          "separator-shutdown",
          "thermal-runaway"
        ],
        "url": "https://lemonergy.com/learn/glossary/ceramic-coated-separator/",
        "mentions": [
          "polyethylene-polypropylene"
        ]
      }
    }
  ]
}