{
  "node": {
    "id": "term:redox-mediator",
    "type": "Term",
    "label": "Redox mediator",
    "properties": {
      "id": "redox-mediator",
      "name": "Redox mediator",
      "aka": [
        "electron shuttle",
        "redox shuttle"
      ],
      "section": "topic-electrochemistry",
      "definition": "A dissolved molecule that is oxidised or reduced at the electrode and then carries that charge to an active material it can reach chemically, such as solid Li₂O₂ in a lithium–air battery, cutting the charging overpotential. Overcharge-protection additives work similarly: a redox shuttle oxidises at a set potential, diffuses to the negative electrode and returns, carrying the excess current.",
      "related": [
        "redox-couple",
        "overcharge",
        "electrolyte-additive",
        "overpotential",
        "redox-reaction"
      ],
      "url": "https://lemonergy.com/learn/glossary/redox-mediator/",
      "mentions": [
        "electrode",
        "negative-electrode",
        "active-material",
        "lithium-air"
      ]
    }
  },
  "edges": [
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      "source": "term:redox-mediator",
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    {
      "id": "edge:6741",
      "source": "term:redox-mediator",
      "target": "term:redox-couple",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6742",
      "source": "term:redox-mediator",
      "target": "term:overcharge",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
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    {
      "id": "edge:6743",
      "source": "term:redox-mediator",
      "target": "term:electrolyte-additive",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6744",
      "source": "term:redox-mediator",
      "target": "term:overpotential",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6745",
      "source": "term:redox-mediator",
      "target": "term:redox-reaction",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/redox-mediator/electrode",
      "source": "term:redox-mediator",
      "target": "term:electrode",
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      "properties": {
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        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
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    {
      "id": "edge:mentions/redox-mediator/negative-electrode",
      "source": "term:redox-mediator",
      "target": "term:negative-electrode",
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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/redox-mediator/active-material",
      "source": "term:redox-mediator",
      "target": "term:active-material",
      "type": "mentions",
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        "sourceFile": "terms.json",
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        "field": "definition",
        "meaning": "Text mention; not a causal claim"
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    {
      "id": "edge:mentions/redox-mediator/lithium-air",
      "source": "term:redox-mediator",
      "target": "term:lithium-air",
      "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-electrochemistry",
      "type": "Topic",
      "label": "Electrochemistry fundamentals",
      "properties": {
        "id": "topic-electrochemistry",
        "name": "Electrochemistry fundamentals",
        "lede": "The reactions and potentials that make a cell a battery.",
        "context": "Connect reaction sites and transport paths.",
        "example": "A circuit can predict terminal voltage while leaving electrode potentials and reaction kinetics unresolved.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/cell-anatomy/",
        "lesson_label": "Open cell anatomy"
      }
    },
    {
      "id": "term:redox-couple",
      "type": "Term",
      "label": "Redox couple",
      "properties": {
        "id": "redox-couple",
        "name": "Redox couple",
        "aka": [
          "redox pair"
        ],
        "section": "topic-electrochemistry",
        "definition": "The oxidised and reduced forms of one species, written oxidised/reduced, such as Fe³⁺/Fe²⁺ or Li⁺/Li, each couple with an electrode potential of its own. A cell’s voltage is the difference between the couples at its two electrodes: the FePO₄/LiFePO₄ couple sits near 3.4 V vs Li/Li⁺, which is the voltage of an LFP cell.",
        "related": [
          "redox-reaction",
          "half-reaction",
          "standard-potential",
          "electrode-potential",
          "cell-voltage",
          "lfp"
        ],
        "url": "https://lemonergy.com/learn/glossary/redox-couple/",
        "mentions": [
          "electrode"
        ]
      }
    },
    {
      "id": "term:overcharge",
      "type": "Term",
      "label": "Overcharge",
      "properties": {
        "id": "overcharge",
        "name": "Overcharge",
        "section": "topic-charging",
        "definition": "Charging past the upper cutoff voltage. The positive electrode over-delithiates and releases oxygen, the electrolyte oxidises and lithium plates on the negative, so an unprotected overcharge can end in thermal runaway.",
        "related": [
          "cutoff-voltage",
          "thermal-runaway",
          "bms",
          "overcharge-test",
          "electrolyte-decomposition"
        ],
        "url": "https://lemonergy.com/learn/glossary/overcharge/",
        "mentions": [
          "electrode",
          "positive-electrode",
          "electrolyte"
        ]
      }
    },
    {
      "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:overpotential",
      "type": "Term",
      "label": "Overpotential",
      "properties": {
        "id": "overpotential",
        "name": "Overpotential",
        "abbr": "η",
        "section": "topic-electrochemistry",
        "definition": "The extra voltage, beyond the equilibrium potential, needed to drive a reaction at a given rate at one electrode. Activation overpotential pays for charge transfer, concentration overpotential for depleted reactant, and both appear as polarization at the terminals.",
        "unit": "V",
        "related": [
          "polarization",
          "butler-volmer",
          "exchange-current-density",
          "concentration-polarization"
        ],
        "url": "https://lemonergy.com/learn/glossary/overpotential/",
        "mentions": [
          "electrode",
          "charge-transfer"
        ]
      }
    },
    {
      "id": "term:redox-reaction",
      "type": "Term",
      "label": "Redox reaction",
      "properties": {
        "id": "redox-reaction",
        "name": "Redox reaction",
        "section": "topic-electrochemistry",
        "definition": "A reaction in which electrons move from one species to another: one is oxidised, the other reduced. A battery separates the two halves onto two electrodes so the electrons must travel through the external circuit.",
        "related": [
          "oxidation",
          "reduction",
          "half-reaction",
          "electrode-potential",
          "galvanic-cell"
        ],
        "lesson": "labs/battery-materials-lab/#bml-aqueous-mechanism",
        "url": "https://lemonergy.com/learn/glossary/redox-reaction/",
        "mentions": []
      }
    },
    {
      "id": "term:electrode",
      "type": "Term",
      "label": "Electrode",
      "properties": {
        "id": "electrode",
        "name": "Electrode",
        "section": "topic-components",
        "definition": "A solid conductor where the cell’s reaction happens, in contact with the electrolyte. A lithium-ion cell has a negative electrode and a positive electrode, each a porous coating on a metal foil.",
        "related": [
          "negative-electrode",
          "positive-electrode",
          "porous-electrode",
          "current-collector"
        ],
        "lesson": "fundamentals/cell-anatomy/#components",
        "example": {
          "title": "Two transport paths",
          "text": "Electrons need connected solid paths to the collector; ions need electrolyte paths to reaction sites. More of one constituent displaces others at fixed volume."
        },
        "url": "https://lemonergy.com/learn/glossary/electrode/",
        "mentions": [
          "electrolyte",
          "coating"
        ]
      }
    },
    {
      "id": "term:negative-electrode",
      "type": "Term",
      "label": "Negative electrode",
      "properties": {
        "id": "negative-electrode",
        "name": "Negative electrode",
        "section": "topic-components",
        "definition": "The electrode at the lower potential, usually graphite on copper foil in a lithium-ion cell. It holds the lithium when the cell is charged and releases it on discharge, and industry calls it the anode.",
        "related": [
          "anode",
          "graphite",
          "positive-electrode",
          "copper-foil"
        ],
        "lesson": "fundamentals/cell-anatomy/#anode-cathode",
        "example": {
          "title": "Keep the polarity name",
          "text": "Graphite remains the negative electrode during charge and discharge, while the anode/cathode reaction labels change with operating direction."
        },
        "url": "https://lemonergy.com/learn/glossary/negative-electrode/",
        "mentions": [
          "electrode"
        ]
      }
    },
    {
      "id": "term:active-material",
      "type": "Term",
      "label": "Active material",
      "properties": {
        "id": "active-material",
        "name": "Active material",
        "abbr": "AM",
        "section": "topic-components",
        "definition": "The part of an electrode that actually stores lithium — graphite on the negative side, an oxide or phosphate on the positive. It makes up most of the electrode coating; the rest is binder and conductive additive.",
        "related": [
          "cathode-active-material",
          "anode-active-material",
          "binder",
          "conductive-additive",
          "specific-capacity"
        ],
        "lesson": "fundamentals/cell-architecture/#composite",
        "example": {
          "title": "Choose a mass basis",
          "text": "A 100 g coating containing 95 g active material has different specific-capacity numbers when normalized to active mass versus total coating mass."
        },
        "url": "https://lemonergy.com/learn/glossary/active-material/",
        "mentions": [
          "electrode",
          "graphite",
          "coating"
        ]
      }
    },
    {
      "id": "term:lithium-air",
      "type": "Term",
      "label": "Lithium–air battery",
      "properties": {
        "id": "lithium-air",
        "name": "Lithium–air battery",
        "abbr": "Li–O₂",
        "aka": [
          "lithium–oxygen battery",
          "Li–air"
        ],
        "section": "topic-other-chemistries",
        "definition": "A cell in which lithium metal reacts with oxygen at a porous carbon positive, forming lithium peroxide on discharge. Counting the peroxide’s mass, theoretical specific energy is about 3,500 Wh/kg, several times lithium-ion. Insulating peroxide clogs the electrode, charging needs large overpotentials, and moisture and CO₂ in real air poison the reaction.",
        "related": [
          "lithium-metal-battery",
          "zinc-air",
          "lithium-sulfur",
          "overpotential",
          "conversion-reaction",
          "redox-mediator"
        ],
        "url": "https://lemonergy.com/learn/glossary/lithium-air/",
        "mentions": [
          "electrode",
          "specific-energy"
        ]
      }
    }
  ]
}