{
  "node": {
    "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"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:6732",
      "source": "term:redox-couple",
      "target": "topic:topic-electrochemistry",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:6733",
      "source": "term:redox-couple",
      "target": "term:redox-reaction",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6734",
      "source": "term:redox-couple",
      "target": "term:half-reaction",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6735",
      "source": "term:redox-couple",
      "target": "term:standard-potential",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6736",
      "source": "term:redox-couple",
      "target": "term:electrode-potential",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6737",
      "source": "term:redox-couple",
      "target": "term:cell-voltage",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6738",
      "source": "term:redox-couple",
      "target": "term:lfp",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/redox-couple/electrode",
      "source": "term:redox-couple",
      "target": "term:electrode",
      "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-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:half-reaction",
      "type": "Term",
      "label": "Half-reaction",
      "properties": {
        "id": "half-reaction",
        "name": "Half-reaction",
        "aka": [
          "half-cell reaction"
        ],
        "section": "topic-electrochemistry",
        "definition": "The oxidation or reduction occurring at one electrode, written on its own with electrons shown explicitly. The cell reaction is the sum of its two half-reactions, and the cell voltage is the difference of their potentials.",
        "related": [
          "redox-reaction",
          "electrode-potential",
          "half-cell",
          "cell-voltage"
        ],
        "lesson": "labs/battery-materials-lab/#bml-liion-mechanism",
        "url": "https://lemonergy.com/learn/glossary/half-reaction/",
        "mentions": [
          "electrode",
          "oxidation",
          "reduction"
        ]
      }
    },
    {
      "id": "term:standard-potential",
      "type": "Term",
      "label": "Standard electrode potential",
      "properties": {
        "id": "standard-potential",
        "name": "Standard electrode potential",
        "abbr": "E°",
        "section": "topic-electrochemistry",
        "definition": "An electrode’s potential under standard conditions, tabulated against the standard hydrogen electrode. Lithium’s −3.04 V is the most negative of any metal, which is why lithium cells have the highest voltages.",
        "unit": "V",
        "related": [
          "electrode-potential",
          "nernst-equation",
          "cell-voltage"
        ],
        "url": "https://lemonergy.com/learn/glossary/standard-potential/",
        "mentions": [
          "electrode",
          "standard-hydrogen-electrode"
        ]
      }
    },
    {
      "id": "term:electrode-potential",
      "type": "Term",
      "label": "Electrode potential",
      "properties": {
        "id": "electrode-potential",
        "name": "Electrode potential",
        "section": "topic-electrochemistry",
        "definition": "The potential of an electrode relative to a reference, which for lithium-ion work is lithium metal in the same electrolyte, written as V vs Li/Li⁺. Graphite sits near 0.1 V and layered oxides near 3.7–4.3 V on this scale.",
        "unit": "V vs Li/Li⁺",
        "related": [
          "standard-potential",
          "cell-voltage",
          "reference-electrode",
          "half-reaction"
        ],
        "lesson": "labs/battery-materials-lab/#battery-materials-lab",
        "url": "https://lemonergy.com/learn/glossary/electrode-potential/",
        "mentions": [
          "electrode",
          "graphite",
          "electrolyte"
        ]
      }
    },
    {
      "id": "term:cell-voltage",
      "type": "Term",
      "label": "Cell voltage",
      "properties": {
        "id": "cell-voltage",
        "name": "Cell voltage",
        "aka": [
          "electromotive force",
          "EMF"
        ],
        "section": "topic-electrochemistry",
        "definition": "The difference between the positive and negative electrode potentials at equilibrium: for NMC against graphite about 3.7 V. It is set by the chemistry, and the difference in Gibbs free energy of the cell reaction per unit charge.",
        "formula": "E = E₊ − E₋ = −ΔG / nF",
        "unit": "V",
        "related": [
          "electrode-potential",
          "gibbs-free-energy",
          "open-circuit-voltage",
          "nominal-voltage"
        ],
        "example": {
          "title": "Subtract equilibrium electrode potentials",
          "text": "If two illustrative electrode potentials are 4.0 V and 0.2 V versus the same reference, their equilibrium cell voltage is 3.8 V. Under load, resistance and polarization change the measured terminal voltage."
        },
        "url": "https://lemonergy.com/learn/glossary/cell-voltage/",
        "mentions": [
          "electrode",
          "negative-electrode",
          "graphite"
        ]
      }
    },
    {
      "id": "term:lfp",
      "type": "Term",
      "label": "LFP",
      "properties": {
        "id": "lfp",
        "name": "LFP",
        "aka": [
          "lithium iron phosphate",
          "LiFePO₄"
        ],
        "section": "topic-chemistries",
        "definition": "A positive electrode material, LiFePO₄, giving cells a nominal voltage around 3.2 V, long cycle life and good thermal stability, but less energy per kilogram than nickel-rich oxides. Its flat voltage curve makes state of charge hard to read from voltage alone.",
        "related": [
          "cathode-active-material",
          "nmc",
          "lmfp",
          "ocv-soc-curve",
          "cycle-life"
        ],
        "lesson": "fundamentals/cell-anatomy/#voltage",
        "example": {
          "title": "Chemistry is not the whole datasheet",
          "text": "Two LFP products can differ in format, loading, capacity and current limits. Their cathode family alone does not make them interchangeable."
        },
        "url": "https://lemonergy.com/learn/glossary/lfp/",
        "mentions": [
          "electrode",
          "positive-electrode",
          "nominal-voltage",
          "discharge-curve",
          "state-of-charge"
        ]
      }
    },
    {
      "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"
        ]
      }
    }
  ]
}