Half cells & three-electrode cells#

How to describe the non-full-cell configurations: one electrode under test against a counter. Neither is a separate record type — both are a cell flavored by cell_configuration (half_cell or three_electrode_cell), with electrodes named by role. The one structural difference: in a half cell the counter electrode IS the potential reference (one electrode, two roles); a three-electrode cell separates them with a dedicated reference_electrode.

Not record types: a cell with cell_configuration set to half_cell or three_electrode_cell.
Electrodes are named by role - working_electrode / counter_electrode / reference_electrode (or their *_spec_id siblings) - never by polarity.
The one structural difference: a half cell’s counter also carries the reference role (one electrode, two classes); a three-electrode cell states a dedicated reference_electrode.
Reference the working electrode’s spec; describe the interchangeable counter (and a reference ring or wire) inline - a metal foil is a monolithic material, never a coating.

Define one#

A coin half cell for electrode characterization#

Python

from battinfo import CellSpec

spec = CellSpec(
    id="https://w3id.org/battinfo/spec/t4wz-ff8s-6vp6-af48",
    manufacturer="Example Lab",
    model="HC-GR-01",
    format="coin",
    chemistry="Li-ion",
    # The half-cell flavor: electrodes are named by ROLE, not polarity.
    cell_configuration="half_cell",
    # The design under test, referenced by its electrode-spec IRI.
    working_electrode_spec_id="https://w3id.org/battinfo/spec/kxwy-5f5f-f682-hhch",
    # The counter is described inline: lithium foil the lab treats as
    # interchangeable earns a description, not a tracked record. In a
    # two-electrode half cell it is also the potential reference. A foil
    # is a monolithic electrode - `material`, never a coating.
    counter_electrode={"material": {"name": "Lithium metal"}},
    source={"type": "lab", "retrieved_at": 1750000000},
)
record = spec.to_record()

Canonical record

{
  "schema_version": "0.2.0",
  "cell_spec": {
    "id": "https://w3id.org/battinfo/spec/t4wz-ff8s-6vp6-af48",
    "short_id": "t4wzff",
    "identifier": "cell-spec:t4wz-ff8s-6vp6-af48",
    "name": "Example Lab HC-GR-01",
    "model": "HC-GR-01",
    "manufacturer": {
      "type": "Organization",
      "name": "Example Lab"
    },
    "cell_format": "coin",
    "chemistry": "Li-ion",
    "cell_configuration": "half_cell"
  },
  "properties": {},
  "provenance": {
    "source_type": "lab",
    "retrieved_at": 1750000000,
    "battinfo_version": "0.7.0"
  },
  "working_electrode_spec_id": "https://w3id.org/battinfo/spec/kxwy-5f5f-f682-hhch",
  "counter_electrode": {
    "material": {
      "name": "Lithium metal",
      "property": {}
    },
    "property": {}
  }
}

JSON-LD

Emitted by record_to_jsonld, hosted-context mode.

{
  "@context": "https://w3id.org/battinfo/context/records/v1.json",
  "@type": [
    "BatteryCellSpecification",
    "schema:ProductModel",
    "schema:CreativeWork"
  ],
  "@id": "https://w3id.org/battinfo/spec/t4wz-ff8s-6vp6-af48",
  "schema:identifier": "t4wz-ff8s-6vp6-af48",
  "schema:name": "Example Lab HC-GR-01",
  "schema:model": "HC-GR-01",
  "schema:manufacturer": {
    "@type": "schema:Organization",
    "schema:name": "Example Lab"
  },
  "schema:url": "https://www.battery-genome.org/registry/spec/t4wz-ff8s-6vp6-af48",
  "isDescriptionFor": {
    "@type": [
      "BatteryCell",
      "CoinCell",
      "BatteryHalfCell",
      "HalfCellDevice",
      "LithiumIonBattery"
    ],
    "@id": "https://w3id.org/battinfo/spec/t4wz-ff8s-6vp6-af48#described",
    "skos:prefLabel": "Example Lab HC-GR-01",
    "hasCounterElectrode": {
      "hasActiveMaterial": {
        "@type": [
          "Lithium",
          "ActiveMaterial"
        ],
        "schema:name": "Lithium metal"
      },
      "@type": [
        "CounterElectrode",
        "ReferenceElectrode"
      ]
    },
    "hasWorkingElectrode": {
      "@id": "https://w3id.org/battinfo/spec/kxwy-5f5f-f682-hhch#described"
    }
  },
  "schema:schemaVersion": "0.2.0",
  "dcterms:source": {
    "@type": "prov:Entity",
    "dcterms:type": "lab",
    "prov:generatedAtTime": "2025-06-15T15:06:40+00:00"
  }
}

What to notice:

The described device types as HalfCellDevice (never ElectrochemicalHalfCell).
The working electrode emits under hasWorkingElectrode as a reference to its spec; the counter node types as BOTH CounterElectrode and ReferenceElectrode.

A three-electrode cell#