{
  "node": {
    "id": "term:nickel-iron",
    "type": "Term",
    "label": "Nickel–iron battery",
    "properties": {
      "id": "nickel-iron",
      "name": "Nickel–iron battery",
      "abbr": "NiFe",
      "aka": [
        "Edison cell",
        "Edison battery"
      ],
      "section": "topic-other-chemistries",
      "definition": "A 1.2 V alkaline rechargeable cell with a nickel oxyhydroxide positive and iron negative, developed by Jungner and Edison around 1900. It is nearly indestructible, tolerating overcharge, deep discharge and decades of use, but low energy density, high self-discharge, hydrogen gassing and poor efficiency confined it to railways, mines and off-grid storage.",
      "related": [
        "nickel-cadmium",
        "nickel-metal-hydride",
        "iron-air",
        "self-discharge",
        "gas-generation"
      ],
      "url": "https://lemonergy.com/learn/glossary/nickel-iron/",
      "mentions": [
        "energy-density",
        "overcharge",
        "over-discharge"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:5943",
      "source": "term:nickel-iron",
      "target": "topic:topic-other-chemistries",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:5944",
      "source": "term:nickel-iron",
      "target": "term:nickel-cadmium",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5945",
      "source": "term:nickel-iron",
      "target": "term:nickel-metal-hydride",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5946",
      "source": "term:nickel-iron",
      "target": "term:iron-air",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5947",
      "source": "term:nickel-iron",
      "target": "term:self-discharge",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5948",
      "source": "term:nickel-iron",
      "target": "term:gas-generation",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/nickel-iron/energy-density",
      "source": "term:nickel-iron",
      "target": "term:energy-density",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/nickel-iron/overcharge",
      "source": "term:nickel-iron",
      "target": "term:overcharge",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/nickel-iron/over-discharge",
      "source": "term:nickel-iron",
      "target": "term:over-discharge",
      "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-other-chemistries",
      "type": "Topic",
      "label": "Other and emerging chemistries",
      "properties": {
        "id": "topic-other-chemistries",
        "name": "Other and emerging chemistries",
        "lede": "Batteries beyond today’s lithium-ion: lead, nickel and primary cells, flow and metal–air batteries, solid-state and lithium-metal cells, and the multivalent and sodium chemistries in development.",
        "context": "Do not carry lithium-ion assumptions into every chemistry.",
        "example": "Two chemistries can meet the same energy target with different voltage windows and charge termination.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/cell-anatomy/",
        "lesson_label": "Open cell anatomy"
      }
    },
    {
      "id": "term:nickel-cadmium",
      "type": "Term",
      "label": "Nickel–cadmium battery",
      "properties": {
        "id": "nickel-cadmium",
        "name": "Nickel–cadmium battery",
        "abbr": "NiCd",
        "section": "topic-other-chemistries",
        "definition": "A 1.2 V aqueous cell, rugged and able to deliver very high currents, but containing toxic cadmium and prone to the memory effect. It is now restricted in most consumer uses and survives in aviation and emergency lighting.",
        "related": [
          "memory-effect",
          "nickel-metal-hydride",
          "recycling"
        ],
        "url": "https://lemonergy.com/learn/glossary/nickel-cadmium/",
        "mentions": []
      }
    },
    {
      "id": "term:nickel-metal-hydride",
      "type": "Term",
      "label": "Nickel–metal hydride battery",
      "properties": {
        "id": "nickel-metal-hydride",
        "name": "Nickel–metal hydride battery",
        "abbr": "NiMH",
        "section": "topic-other-chemistries",
        "definition": "A 1.2 V aqueous cell with a nickel hydroxide positive electrode and a hydrogen-absorbing alloy negative. It powered hybrid cars for two decades and is tolerant of abuse, but lithium-ion stores two to three times more energy per kilogram.",
        "related": [
          "hybrid-vehicle",
          "memory-effect",
          "specific-energy",
          "bipolar-battery",
          "nickel-hydrogen"
        ],
        "url": "https://lemonergy.com/learn/glossary/nickel-metal-hydride/",
        "mentions": [
          "electrode",
          "positive-electrode"
        ]
      }
    },
    {
      "id": "term:iron-air",
      "type": "Term",
      "label": "Iron–air battery",
      "properties": {
        "id": "iron-air",
        "name": "Iron–air battery",
        "aka": [
          "Fe–air battery",
          "rust battery"
        ],
        "section": "topic-other-chemistries",
        "definition": "A rechargeable alkaline cell that oxidises iron to iron hydroxide — reversible rusting — with oxygen drawn from the air, then reduces it back on charge. Iron is cheap enough that systems built for about 100 hours of discharge make sense for multi-day grid storage, though round-trip efficiency is low and hydrogen evolution on the iron wastes charge.",
        "related": [
          "long-duration-storage",
          "zinc-air",
          "nickel-iron",
          "stationary-storage",
          "levelized-cost-of-storage",
          "energy-efficiency"
        ],
        "url": "https://lemonergy.com/learn/glossary/iron-air/",
        "mentions": [
          "alkaline-cell"
        ]
      }
    },
    {
      "id": "term:self-discharge",
      "type": "Term",
      "label": "Self-discharge",
      "properties": {
        "id": "self-discharge",
        "name": "Self-discharge",
        "section": "topic-charging",
        "definition": "The slow loss of stored charge while a cell is not in use. An unexpected rise can signal a leakage path or a soft internal short.",
        "unit": "%/month",
        "related": [
          "internal-short-circuit",
          "calendar-aging",
          "k-value",
          "calendar-life",
          "self-discharge-test"
        ],
        "lesson": "fundamentals/battery-aging/#check-yourself",
        "url": "https://lemonergy.com/learn/glossary/self-discharge/",
        "mentions": []
      }
    },
    {
      "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:energy-density",
      "type": "Term",
      "label": "Energy density",
      "properties": {
        "id": "energy-density",
        "name": "Energy density",
        "aka": [
          "volumetric energy density"
        ],
        "section": "topic-ratings",
        "definition": "Stored energy per unit volume, in watt-hours per litre. It is the figure that matters when space is the constraint, as in a phone or under a car floor; high-energy cylindrical cells pass 700 Wh/L.",
        "unit": "Wh/L",
        "related": [
          "specific-energy",
          "nominal-energy",
          "ragone-plot",
          "areal-loading"
        ],
        "lesson": "fundamentals/capacity-and-c-rate/#energy",
        "url": "https://lemonergy.com/learn/glossary/energy-density/",
        "mentions": []
      }
    },
    {
      "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:over-discharge",
      "type": "Term",
      "label": "Over-discharge",
      "properties": {
        "id": "over-discharge",
        "name": "Over-discharge",
        "aka": [
          "deep discharge"
        ],
        "section": "topic-charging",
        "definition": "Discharging below the lower cutoff voltage. Near 1.5 V the copper current collector begins to dissolve, and on the next charge it can redeposit as metal that shorts the cell, so a deeply discharged cell should not simply be recharged.",
        "related": [
          "cutoff-voltage",
          "copper-dissolution",
          "internal-short-circuit",
          "bms",
          "low-voltage-disconnect"
        ],
        "url": "https://lemonergy.com/learn/glossary/over-discharge/",
        "mentions": [
          "current-collector"
        ]
      }
    }
  ]
}