{
  "node": {
    "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"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:belongsTo/term:polyanionic-cathode/topic:topic-other-chemistries",
      "source": "term:polyanionic-cathode",
      "target": "topic:topic-other-chemistries",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:relatedTo/term:polyanionic-cathode/term:lfp",
      "source": "term:polyanionic-cathode",
      "target": "term:lfp",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:polyanionic-cathode/term:olivine-structure",
      "source": "term:polyanionic-cathode",
      "target": "term:olivine-structure",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:polyanionic-cathode/term:sodium-ion",
      "source": "term:polyanionic-cathode",
      "target": "term:sodium-ion",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:polyanionic-cathode/term:prussian-blue-analogue",
      "source": "term:polyanionic-cathode",
      "target": "term:prussian-blue-analogue",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:polyanionic-cathode/term:layered-oxide",
      "source": "term:polyanionic-cathode",
      "target": "term:layered-oxide",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/polyanionic-cathode/nfpp",
      "source": "term:polyanionic-cathode",
      "target": "term:nfpp",
      "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: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:olivine-structure",
      "type": "Term",
      "label": "Olivine structure",
      "properties": {
        "id": "olivine-structure",
        "name": "Olivine structure",
        "aka": [
          "LiMPO₄ structure",
          "phospho-olivine"
        ],
        "section": "topic-chemistries",
        "definition": "The orthorhombic structure of LiFePO₄ and its relatives, in which phosphate groups lock oxygen in place and lithium lies in one-dimensional channels. Strong phosphorus–oxygen bonds make the material thermally stable and long-lived, but one-dimensional diffusion and poor electronic conductivity call for small, carbon-coated particles. LMFP substitutes manganese to raise the voltage.",
        "related": [
          "lfp",
          "lmfp",
          "polyanionic-cathode",
          "spinel-structure",
          "layered-oxide",
          "particle-size"
        ],
        "url": "https://lemonergy.com/learn/glossary/olivine-structure/",
        "mentions": [
          "electronic-conductivity",
          "diffusion",
          "manganese"
        ]
      }
    },
    {
      "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"
        ]
      }
    },
    {
      "id": "term:prussian-blue-analogue",
      "type": "Term",
      "label": "Prussian blue analogue",
      "properties": {
        "id": "prussian-blue-analogue",
        "name": "Prussian blue analogue",
        "abbr": "PBA",
        "aka": [
          "Prussian white",
          "hexacyanoferrate",
          "Prussian blue",
          "PB"
        ],
        "section": "topic-other-chemistries",
        "definition": "An open-framework compound, AₓM[Fe(CN)₆], in which iron–cyanide units and another metal form a cubic cage with wide channels for large ions. Made at low temperature from cheap elements, its sodium-rich form, Prussian white, is a leading sodium-ion cathode. Water trapped in the lattice degrades cells, and the cyanide groups raise questions in thermal runaway.",
        "related": [
          "sodium-ion",
          "potassium-ion",
          "cathode-active-material",
          "moisture-content",
          "ammonium-ion"
        ],
        "url": "https://lemonergy.com/learn/glossary/prussian-blue-analogue/",
        "mentions": [
          "cathode",
          "thermal-runaway"
        ]
      }
    },
    {
      "id": "term:layered-oxide",
      "type": "Term",
      "label": "Layered oxide",
      "properties": {
        "id": "layered-oxide",
        "name": "Layered oxide",
        "abbr": "LTMO",
        "aka": [
          "layered transition-metal oxide",
          "α-NaFeO₂ structure",
          "O3 structure",
          "P2 structure"
        ],
        "section": "topic-chemistries",
        "definition": "The crystal structure of LCO, NMC and NCA: close-packed oxygen layers with lithium and transition-metal ions in alternate layers of octahedral sites, so lithium moves in two-dimensional sheets. The structure offers high capacity and voltage but can distort or mix cations when deeply delithiated. Sodium versions are labelled O3 or P2 by their stacking.",
        "related": [
          "nmc",
          "lco",
          "nca",
          "structural-degradation",
          "spinel-structure",
          "sodium-ion"
        ],
        "url": "https://lemonergy.com/learn/glossary/layered-oxide/",
        "mentions": [
          "stacking"
        ]
      }
    },
    {
      "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"
        ]
      }
    }
  ]
}