{
  "node": {
    "id": "term:fec",
    "type": "Term",
    "label": "Fluoroethylene carbonate",
    "properties": {
      "id": "fec",
      "name": "Fluoroethylene carbonate",
      "abbr": "FEC",
      "section": "topic-electrolytes",
      "definition": "A fluorinated additive, sometimes a co-solvent, that forms a lithium-fluoride-rich SEI able to survive the large volume changes of silicon and lithium-metal electrodes. It is almost universal in silicon-blend cells.",
      "related": [
        "electrolyte-additive",
        "vc",
        "silicon-anode",
        "sei"
      ],
      "url": "https://lemonergy.com/learn/glossary/fec/",
      "mentions": []
    }
  },
  "edges": [
    {
      "id": "edge:3402",
      "source": "term:fec",
      "target": "topic:topic-electrolytes",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:3403",
      "source": "term:fec",
      "target": "term:electrolyte-additive",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3404",
      "source": "term:fec",
      "target": "term:vc",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3405",
      "source": "term:fec",
      "target": "term:silicon-anode",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3406",
      "source": "term:fec",
      "target": "term:sei",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3407",
      "source": "term:fec",
      "target": "reference:xu-electrolytes",
      "type": "cites",
      "properties": {
        "sourceFile": "wiki-references.json",
        "scope": "direct technical reference"
      }
    }
  ],
  "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:electrolyte-additive",
      "type": "Term",
      "label": "Electrolyte additive",
      "properties": {
        "id": "electrolyte-additive",
        "name": "Electrolyte additive",
        "aka": [
          "VC",
          "FEC"
        ],
        "section": "topic-electrolytes",
        "definition": "A compound added to the electrolyte at a few percent to improve one property — vinylene carbonate and fluoroethylene carbonate build a tougher SEI, others suppress gassing or overcharge. Additive packages are among a cell maker’s closest secrets.",
        "related": [
          "electrolyte",
          "sei",
          "formation",
          "gas-generation",
          "libob"
        ],
        "url": "https://lemonergy.com/learn/glossary/electrolyte-additive/",
        "mentions": [
          "overcharge",
          "vc",
          "fec"
        ]
      }
    },
    {
      "id": "term:vc",
      "type": "Term",
      "label": "Vinylene carbonate",
      "properties": {
        "id": "vc",
        "name": "Vinylene carbonate",
        "abbr": "VC",
        "section": "topic-electrolytes",
        "definition": "The most common SEI-forming additive, used at 1–3 %. It is reduced before the solvent on the first charge and polymerises into a thinner, more flexible SEI that lengthens cycle life.",
        "related": [
          "electrolyte-additive",
          "sei",
          "fec",
          "formation"
        ],
        "url": "https://lemonergy.com/learn/glossary/vc/",
        "mentions": [
          "cycle-life"
        ]
      }
    },
    {
      "id": "term:silicon-anode",
      "type": "Term",
      "label": "Silicon anode",
      "properties": {
        "id": "silicon-anode",
        "name": "Silicon anode",
        "aka": [
          "silicon-graphite",
          "SiOx"
        ],
        "section": "topic-components",
        "definition": "A negative electrode that uses silicon, which alloys with lithium and stores roughly ten times more charge per gram than graphite but swells by up to 300 %. Today it is blended into graphite at a few percent to limit the swelling.",
        "related": [
          "graphite",
          "alloying",
          "particle-cracking",
          "swelling",
          "self-healing-binder"
        ],
        "example": {
          "title": "Read the mixture basis",
          "text": "A silicon-containing electrode may be a blend rather than pure silicon. A silicon percentage needs a clear mass basis."
        },
        "url": "https://lemonergy.com/learn/glossary/silicon-anode/",
        "mentions": [
          "electrode",
          "negative-electrode"
        ]
      }
    },
    {
      "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"
        ],
        "lesson": "fundamentals/battery-aging/#sei",
        "url": "https://lemonergy.com/learn/glossary/sei/",
        "mentions": [
          "electrode",
          "graphite",
          "electrolyte"
        ]
      }
    },
    {
      "id": "reference:xu-electrolytes",
      "type": "Reference",
      "label": "Electrolytes and Interphases in Li-Ion Batteries and Beyond",
      "properties": {
        "title": "Electrolytes and Interphases in Li-Ion Batteries and Beyond",
        "publisher": "Chemical Reviews",
        "url": "https://doi.org/10.1021/cr500003w",
        "type": "Review article",
        "scope": "Electrolyte salts, solvents, additives and electrode interphases.",
        "year": 2014,
        "authors": [
          "Kang Xu"
        ],
        "accessed": "2026-10-27"
      }
    }
  ]
}