{
  "node": {
    "id": "term:differential-electrochemical-mass-spectrometry",
    "type": "Term",
    "label": "Differential electrochemical mass spectrometry",
    "properties": {
      "id": "differential-electrochemical-mass-spectrometry",
      "name": "Differential electrochemical mass spectrometry",
      "abbr": "DEMS",
      "aka": [
        "OEMS",
        "online electrochemical mass spectrometry"
      ],
      "section": "topic-analysis",
      "definition": "Feeding gas from an operating cell straight into a mass spectrometer, so each species is identified and quantified as it forms. It shows ethylene from ethylene carbonate reduction during formation, and the oxygen and carbon dioxide released by layered oxides at high state of charge, tying each gas to the voltage that made it.",
      "related": [
        "gas-generation",
        "off-gas",
        "electrolyte-decomposition",
        "formation",
        "operando-measurement",
        "gas-chromatography-mass-spectrometry"
      ],
      "url": "https://lemonergy.com/learn/glossary/differential-electrochemical-mass-spectrometry/",
      "mentions": [
        "state-of-charge",
        "reduction",
        "ec"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:5526",
      "source": "term:differential-electrochemical-mass-spectrometry",
      "target": "topic:topic-analysis",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
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    },
    {
      "id": "edge:5527",
      "source": "term:differential-electrochemical-mass-spectrometry",
      "target": "term:gas-generation",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5528",
      "source": "term:differential-electrochemical-mass-spectrometry",
      "target": "term:off-gas",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5529",
      "source": "term:differential-electrochemical-mass-spectrometry",
      "target": "term:electrolyte-decomposition",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5530",
      "source": "term:differential-electrochemical-mass-spectrometry",
      "target": "term:formation",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5531",
      "source": "term:differential-electrochemical-mass-spectrometry",
      "target": "term:operando-measurement",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5532",
      "source": "term:differential-electrochemical-mass-spectrometry",
      "target": "term:gas-chromatography-mass-spectrometry",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/differential-electrochemical-mass-spectrometry/state-of-charge",
      "source": "term:differential-electrochemical-mass-spectrometry",
      "target": "term:state-of-charge",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
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        "meaning": "Text mention; not a causal claim"
      }
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    {
      "id": "edge:mentions/differential-electrochemical-mass-spectrometry/reduction",
      "source": "term:differential-electrochemical-mass-spectrometry",
      "target": "term:reduction",
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      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
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    {
      "id": "edge:mentions/differential-electrochemical-mass-spectrometry/ec",
      "source": "term:differential-electrochemical-mass-spectrometry",
      "target": "term:ec",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
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    }
  ],
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    {
      "id": "topic:topic-analysis",
      "type": "Topic",
      "label": "Materials analysis and post-mortem",
      "properties": {
        "id": "topic-analysis",
        "name": "Materials analysis and post-mortem",
        "lede": "The laboratory techniques that look inside electrodes, interphases and electrolytes to see what a cell is made of and how it aged.",
        "context": "Connect results with scale and specimen preparation.",
        "example": "Surface and bulk measurements may find different compositions in the same electrode without contradiction.",
        "lesson_url": "https://lemonergy.com/learn/labs/battery-materials-lab/",
        "lesson_label": "Open materials lab"
      }
    },
    {
      "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"
        ]
      }
    },
    {
      "id": "term:off-gas",
      "type": "Term",
      "label": "Off-gas",
      "properties": {
        "id": "off-gas",
        "name": "Off-gas",
        "aka": [
          "vent gas"
        ],
        "section": "topic-safety",
        "definition": "The mixture released when a cell vents: electrolyte vapour, hydrogen, carbon monoxide, carbon dioxide and hydrocarbons, with hydrogen fluoride. It is flammable and toxic, and gas sensors detect it before smoke or heat in a storage container.",
        "related": [
          "venting",
          "hydrofluoric-acid",
          "gas-detection",
          "thermal-runaway"
        ],
        "url": "https://lemonergy.com/learn/glossary/off-gas/",
        "mentions": [
          "electrolyte"
        ]
      }
    },
    {
      "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: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:operando-measurement",
      "type": "Term",
      "label": "Operando and in-situ measurement",
      "properties": {
        "id": "operando-measurement",
        "name": "Operando and in-situ measurement",
        "aka": [
          "operando",
          "in situ",
          "in-situ",
          "ex situ"
        ],
        "section": "topic-analysis",
        "definition": "Measuring a cell inside its working environment rather than after taking it apart (ex situ): in situ means within the cell or its surroundings, operando means while it is actually charging or discharging. Operando methods catch transient states, such as phases or plated lithium that vanish during rest or disassembly.",
        "related": [
          "post-mortem",
          "x-ray-diffraction",
          "differential-electrochemical-mass-spectrometry",
          "neutron-imaging-diffraction",
          "instrumented-cell"
        ],
        "url": "https://lemonergy.com/learn/glossary/operando-measurement/",
        "mentions": [
          "dismantling"
        ]
      }
    },
    {
      "id": "term:gas-chromatography-mass-spectrometry",
      "type": "Term",
      "label": "Gas chromatography–mass spectrometry",
      "properties": {
        "id": "gas-chromatography-mass-spectrometry",
        "name": "Gas chromatography–mass spectrometry",
        "abbr": "GC-MS",
        "aka": [
          "gas chromatography",
          "GC"
        ],
        "section": "topic-analysis",
        "definition": "Separating the volatile components of a sample in a heated column and identifying each by its mass spectrum. It measures electrolyte composition and aging products such as transesterified solvents and oligomers; with thermal-conductivity detection it also quantifies hydrogen, carbon monoxide, carbon dioxide and hydrocarbons in cell and vent gas.",
        "related": [
          "electrolyte-decomposition",
          "off-gas",
          "gas-generation",
          "differential-electrochemical-mass-spectrometry",
          "post-mortem"
        ],
        "url": "https://lemonergy.com/learn/glossary/gas-chromatography-mass-spectrometry/",
        "mentions": [
          "electrolyte"
        ]
      }
    },
    {
      "id": "term:state-of-charge",
      "type": "Term",
      "label": "State of charge",
      "properties": {
        "id": "state-of-charge",
        "name": "State of charge",
        "abbr": "SOC",
        "section": "topic-state",
        "definition": "How full a cell is, as a fraction of its available capacity. State of charge, like temperature, affects how fast a stored cell ages.",
        "unit": "%",
        "related": [
          "depth-of-discharge",
          "ocv-soc-curve",
          "coulomb-counting",
          "state-of-health",
          "bms"
        ],
        "lesson": "fundamentals/battery-aging/#storage-soc",
        "example": {
          "title": "Interpret a charge inventory",
          "text": "If available capacity is 5 Ah and 3 Ah remains by the chosen estimator, SOC is 60%. A different estimate of available capacity changes this percentage, so compare SOC values only with the capacity convention recorded."
        },
        "url": "https://lemonergy.com/learn/glossary/state-of-charge/",
        "mentions": [
          "usable-capacity"
        ]
      }
    },
    {
      "id": "term:reduction",
      "type": "Term",
      "label": "Reduction",
      "properties": {
        "id": "reduction",
        "name": "Reduction",
        "section": "topic-electrochemistry",
        "definition": "Gain of electrons by a species. On discharge the positive electrode is reduced as it takes up lithium ions and electrons, which is why it is called the cathode.",
        "related": [
          "oxidation",
          "cathode",
          "redox-reaction"
        ],
        "url": "https://lemonergy.com/learn/glossary/reduction/",
        "mentions": [
          "electrode",
          "positive-electrode"
        ]
      }
    },
    {
      "id": "term:ec",
      "type": "Term",
      "label": "Ethylene carbonate",
      "properties": {
        "id": "ec",
        "name": "Ethylene carbonate",
        "abbr": "EC",
        "section": "topic-electrolytes",
        "definition": "The cyclic carbonate solvent that every graphite cell needs: it is reduced on the first charge into the stable SEI that lets graphite work at all. It is solid at room temperature, so it is always blended with linear carbonates.",
        "related": [
          "carbonate-solvent",
          "sei",
          "pc",
          "dmc",
          "emc"
        ],
        "url": "https://lemonergy.com/learn/glossary/ec/",
        "mentions": [
          "graphite"
        ]
      }
    }
  ]
}