{
  "node": {
    "id": "term:sodium-ion",
    "type": "Term",
    "label": "Sodium-ion battery",
    "properties": {
      "id": "sodium-ion",
      "name": "Sodium-ion battery",
      "abbr": "Na-ion",
      "section": "topic-other-chemistries",
      "definition": "A cell built like a lithium-ion cell but shuttling sodium ions, usually between a hard-carbon negative and a layered-oxide (NFM), polyanionic (NFPP, NVP) or Prussian-blue positive. It uses no lithium or cobalt and needs no copper foil, so it can be stored at 0 V, at the cost of lower energy density.",
      "related": [
        "hard-carbon",
        "nfpp",
        "lithium-ion",
        "energy-density",
        "stationary-storage",
        "seawater-battery"
      ],
      "aka": [
        "SIB",
        "Na-ion battery",
        "sodium-ion cell"
      ],
      "url": "https://lemonergy.com/learn/glossary/sodium-ion/",
      "mentions": [
        "copper-foil",
        "nfm",
        "nvp",
        "cobalt",
        "polyanionic-cathode"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:belongsTo/term:sodium-ion/topic:topic-other-chemistries",
      "source": "term:sodium-ion",
      "target": "topic:topic-other-chemistries",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:relatedTo/term:sodium-ion/term:hard-carbon",
      "source": "term:sodium-ion",
      "target": "term:hard-carbon",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:sodium-ion/term:nfpp",
      "source": "term:sodium-ion",
      "target": "term:nfpp",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:sodium-ion/term:lithium-ion",
      "source": "term:sodium-ion",
      "target": "term:lithium-ion",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:sodium-ion/term:energy-density",
      "source": "term:sodium-ion",
      "target": "term:energy-density",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:sodium-ion/term:stationary-storage",
      "source": "term:sodium-ion",
      "target": "term:stationary-storage",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:sodium-ion/term:seawater-battery",
      "source": "term:sodium-ion",
      "target": "term:seawater-battery",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/sodium-ion/copper-foil",
      "source": "term:sodium-ion",
      "target": "term:copper-foil",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/sodium-ion/nfm",
      "source": "term:sodium-ion",
      "target": "term:nfm",
      "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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    },
    {
      "id": "edge:mentions/sodium-ion/nvp",
      "source": "term:sodium-ion",
      "target": "term:nvp",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/sodium-ion/cobalt",
      "source": "term:sodium-ion",
      "target": "term:cobalt",
      "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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    {
      "id": "edge:mentions/sodium-ion/polyanionic-cathode",
      "source": "term:sodium-ion",
      "target": "term:polyanionic-cathode",
      "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:hard-carbon",
      "type": "Term",
      "label": "Hard carbon",
      "properties": {
        "id": "hard-carbon",
        "name": "Hard carbon",
        "section": "topic-components",
        "definition": "A disordered, non-graphitisable carbon used as the negative electrode of sodium-ion cells, where graphite barely works, and as a fast-charge additive in lithium-ion. Its open structure accepts ions without the strict layer spacing of graphite.",
        "related": [
          "sodium-ion",
          "graphite",
          "anode-active-material"
        ],
        "url": "https://lemonergy.com/learn/glossary/hard-carbon/",
        "mentions": [
          "electrode",
          "negative-electrode"
        ]
      }
    },
    {
      "id": "term:nfpp",
      "type": "Term",
      "label": "Sodium iron pyrophosphate-phosphate",
      "properties": {
        "id": "nfpp",
        "name": "Sodium iron pyrophosphate-phosphate",
        "abbr": "NFPP",
        "aka": [
          "Na₄Fe₃(PO₄)₂P₂O₇",
          "sodium iron phosphate-pyrophosphate"
        ],
        "section": "topic-other-chemistries",
        "definition": "A polyanionic sodium-ion positive electrode, Na₄Fe₃(PO₄)₂P₂O₇, made from cheap iron and phosphate. With a hard-carbon negative it gives cells of about 2.8–3.0 V nominal with long cycle life and good thermal stability, but less energy than layered oxides. It plays the role LFP plays among lithium-ion chemistries.",
        "related": [
          "sodium-ion",
          "polyanionic-cathode",
          "hard-carbon",
          "lfp",
          "nvp",
          "nfm"
        ],
        "url": "https://lemonergy.com/learn/glossary/nfpp/",
        "mentions": [
          "electrode",
          "positive-electrode",
          "cycle-life"
        ]
      }
    },
    {
      "id": "term:lithium-ion",
      "type": "Term",
      "label": "Lithium-ion battery",
      "properties": {
        "id": "lithium-ion",
        "name": "Lithium-ion battery",
        "abbr": "Li-ion",
        "section": "topic-chemistries",
        "definition": "A rechargeable cell in which lithium ions shuttle between two intercalation electrodes, typically graphite and a lithium metal oxide, through a non-aqueous electrolyte. Commercialised in 1991, it dominates portable electronics, electric vehicles and new grid storage.",
        "related": [
          "intercalation",
          "graphite",
          "nmc",
          "lfp",
          "rocking-chair",
          "lithium"
        ],
        "lesson": "fundamentals/battery-basics/#how-it-works",
        "url": "https://lemonergy.com/learn/glossary/lithium-ion/",
        "mentions": [
          "electrolyte"
        ]
      }
    },
    {
      "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:stationary-storage",
      "type": "Term",
      "label": "Stationary storage",
      "properties": {
        "id": "stationary-storage",
        "name": "Stationary storage",
        "abbr": "BESS",
        "aka": [
          "battery energy storage system",
          "ESS"
        ],
        "section": "topic-applications",
        "definition": "Batteries installed in a fixed place — a container at a solar farm, a cabinet in a home — to shift energy in time or support the grid. LFP cells dominate because cost per cycle and safety matter more than mass.",
        "related": [
          "lfp",
          "energy-management-system",
          "inverter",
          "energy-arbitrage",
          "long-duration-storage",
          "ul-9540a"
        ],
        "url": "https://lemonergy.com/learn/glossary/stationary-storage/",
        "mentions": []
      }
    },
    {
      "id": "term:seawater-battery",
      "type": "Term",
      "label": "Seawater battery",
      "properties": {
        "id": "seawater-battery",
        "name": "Seawater battery",
        "aka": [
          "seawater-activated battery",
          "rechargeable seawater battery"
        ],
        "section": "topic-other-chemistries",
        "definition": "A battery that uses seawater as its electrolyte or positive reactant. Seawater-activated primaries, such as magnesium–silver chloride cells, sit dry for years and start when immersed, powering sonobuoys and life-jacket lights. Rechargeable versions pull sodium ions from seawater through a NASICON ceramic into a sealed negative electrode, with oxygen reactions on the open seawater side.",
        "related": [
          "nasicon",
          "sodium-ion",
          "primary-cell",
          "zinc-air",
          "aqueous-battery"
        ],
        "url": "https://lemonergy.com/learn/glossary/seawater-battery/",
        "mentions": [
          "electrode",
          "negative-electrode",
          "electrolyte"
        ]
      }
    },
    {
      "id": "term:copper-foil",
      "type": "Term",
      "label": "Copper foil",
      "properties": {
        "id": "copper-foil",
        "name": "Copper foil",
        "section": "topic-components",
        "definition": "The negative current collector, typically 6–10 µm thick. Copper is used because it is stable at the low potential of a graphite electrode, where aluminium would alloy with lithium.",
        "related": [
          "current-collector",
          "aluminium-foil",
          "over-discharge",
          "copper-dissolution"
        ],
        "example": {
          "title": "Count collector mass",
          "text": "At equal area and density, doubling foil thickness doubles foil mass. Active-material-only capacity omits that mass change."
        },
        "url": "https://lemonergy.com/learn/glossary/copper-foil/",
        "mentions": [
          "electrode",
          "graphite"
        ]
      }
    },
    {
      "id": "term:nfm",
      "type": "Term",
      "label": "Sodium nickel-iron-manganese oxide",
      "properties": {
        "id": "nfm",
        "name": "Sodium nickel-iron-manganese oxide",
        "abbr": "NFM",
        "aka": [
          "NaNi⅓Fe⅓Mn⅓O₂",
          "sodium layered oxide"
        ],
        "section": "topic-other-chemistries",
        "definition": "A layered-oxide sodium-ion positive electrode containing nickel, iron and manganese, usually in the O3 structure. It gives the most energy of the common sodium-ion cathodes, with cells around 3.0–3.1 V nominal, but it is sensitive to moisture and typically lasts fewer cycles than polyanionic NFPP.",
        "related": [
          "sodium-ion",
          "layered-oxide",
          "nfpp",
          "hard-carbon",
          "energy-density"
        ],
        "url": "https://lemonergy.com/learn/glossary/nfm/",
        "mentions": [
          "electrode",
          "positive-electrode",
          "polyanionic-cathode",
          "manganese"
        ]
      }
    },
    {
      "id": "term:nvp",
      "type": "Term",
      "label": "Sodium vanadium phosphate",
      "properties": {
        "id": "nvp",
        "name": "Sodium vanadium phosphate",
        "abbr": "NVP",
        "aka": [
          "Na₃V₂(PO₄)₃"
        ],
        "section": "topic-other-chemistries",
        "definition": "A polyanionic sodium-ion positive electrode, Na₃V₂(PO₄)₃, with a NASICON-type framework of open three-dimensional channels through which sodium moves quickly. Cells reach about 2.9–3.1 V nominal and suit high power and very long cycle life; vanadium makes the material costlier than iron-based NFPP.",
        "related": [
          "sodium-ion",
          "polyanionic-cathode",
          "nfpp",
          "hard-carbon",
          "power-cell-energy-cell"
        ],
        "url": "https://lemonergy.com/learn/glossary/nvp/",
        "mentions": [
          "electrode",
          "positive-electrode",
          "cycle-life"
        ]
      }
    },
    {
      "id": "term:cobalt",
      "type": "Term",
      "label": "Cobalt",
      "properties": {
        "id": "cobalt",
        "name": "Cobalt",
        "section": "topic-sustainability",
        "definition": "The metal that stabilises layered-oxide cathodes, mined largely in the Democratic Republic of Congo under scrutiny for working conditions. Its price and ethics have driven the industry from LCO and NMC111 towards high-nickel and cobalt-free LFP.",
        "related": [
          "nmc",
          "lco",
          "high-nickel",
          "critical-raw-materials",
          "due-diligence"
        ],
        "url": "https://lemonergy.com/learn/glossary/cobalt/",
        "mentions": []
      }
    },
    {
      "id": "term:polyanionic-cathode",
      "type": "Term",
      "label": "Polyanionic cathode",
      "properties": {
        "id": "polyanionic-cathode",
        "name": "Polyanionic cathode",
        "aka": [
          "polyanion cathode",
          "NVPF",
          "NFPP",
          "phosphate cathode"
        ],
        "section": "topic-other-chemistries",
        "definition": "A positive material built from transition metals and polyanion groups such as PO₄³⁻, SO₄²⁻ or P₂O₇⁴⁻. The strongly bonded groups raise the voltage through the inductive effect and hold oxygen tightly, giving long life and safety at some cost in capacity and conductivity. LFP is the lithium example; Na₃V₂(PO₄)₂F₃ and iron-based Na₄Fe₃(PO₄)₂P₂O₇ serve sodium-ion cells.",
        "related": [
          "lfp",
          "olivine-structure",
          "sodium-ion",
          "prussian-blue-analogue",
          "layered-oxide"
        ],
        "url": "https://lemonergy.com/learn/glossary/polyanionic-cathode/",
        "mentions": [
          "nfpp"
        ]
      }
    }
  ]
}