---
title: "Get ConversionElectrodeDoc documents"
method: GET
path: "/materials/conversion_electrodes/"
tags: ["Materials Electrodes"]
---

# Get ConversionElectrodeDoc documents

`GET /materials/conversion_electrodes/`

## Query parameters

- `battery_ids` string — Comma-separated list of battery_id values to query on.
- `working_ion` string, nullable
- `num_steps_max` integer, nullable — Query for maximum value of num_steps
- `num_steps_min` integer, nullable — Query for minimum value of num_steps
- `num_steps` integer, nullable — Query for num_steps being equal to an exact value
- `num_steps_not_eq` integer, nullable — Query for num_steps being not equal to an exact value
- `num_steps_eq_any` string — Query for num_steps being any of these values. Provide a comma separated list.
- `num_steps_neq_any` string — Query for num_steps being not any of these values. Provide a comma separated list.
- `max_voltage_step_max` number, nullable — Query for maximum value of max_voltage_step
- `max_voltage_step_min` number, nullable — Query for minimum value of max_voltage_step
- `nelements_max` integer, nullable — Query for maximum value of nelements
- `nelements_min` integer, nullable — Query for minimum value of nelements
- `nelements` integer, nullable — Query for nelements being equal to an exact value
- `nelements_not_eq` integer, nullable — Query for nelements being not equal to an exact value
- `nelements_eq_any` string — Query for nelements being any of these values. Provide a comma separated list.
- `nelements_neq_any` string — Query for nelements being not any of these values. Provide a comma separated list.
- `max_delta_volume_max` number, nullable — Query for maximum value of max_delta_volume
- `max_delta_volume_min` number, nullable — Query for minimum value of max_delta_volume
- `average_voltage_max` number, nullable — Query for maximum value of average_voltage
- `average_voltage_min` number, nullable — Query for minimum value of average_voltage
- `capacity_grav_max` number, nullable — Query for maximum value of capacity_grav
- `capacity_grav_min` number, nullable — Query for minimum value of capacity_grav
- `capacity_vol_max` number, nullable — Query for maximum value of capacity_vol
- `capacity_vol_min` number, nullable — Query for minimum value of capacity_vol
- `energy_grav_max` number, nullable — Query for maximum value of energy_grav
- `energy_grav_min` number, nullable — Query for minimum value of energy_grav
- `energy_vol_max` number, nullable — Query for maximum value of energy_vol
- `energy_vol_min` number, nullable — Query for minimum value of energy_vol
- `fracA_charge_max` number, nullable — Query for maximum value of fracA_charge
- `fracA_charge_min` number, nullable — Query for minimum value of fracA_charge
- `fracA_discharge_max` number, nullable — Query for maximum value of fracA_discharge
- `fracA_discharge_min` number, nullable — Query for minimum value of fracA_discharge
- `_page` integer — Page number to request (takes precedent over _limit and _skip).
- `_per_page` integer — Number of entries to show per page (takes precedent over _limit and _skip). Limited to 1000.
- `_skip` integer — Number of entries to skip in the search.
- `_limit` integer — Max number of entries to return in a single query. Limited to 1000.
- `_fields` string — Fields to project from ConversionElectrodeDoc as a list of comma separated strings. Fields include: `builder_meta` `battery_type` `material_ids` `thermo_type` `battery_formula` `working_ion` `num_steps` `max_voltage_step` `last_updated` `framework` `framework_formula` `elements` `nelements` `chemsys` `formula_anonymous` `warnings` `formula_charge` `formula_discharge` `max_delta_volume` `average_voltage` `capacity_grav` `capacity_vol` `energy_grav` `energy_vol` `fracA_charge` `fracA_discharge` `reaction` `initial_comp_formula` `adj_pairs` `electrode_object`
- `_all_fields` boolean — Include all fields.
- `id_format` string, nullable — Optional. If set to 'legacy', MP identifier fields in the response are returned in the form 'mp-149'. If set to 'alpha', they are returned in the padded AlphaID form 'mp-aaaaaaft'. If omitted (or set to any other value), identifiers are returned in their stored form. This is a purely cosmetic transform; query inputs accept either shape regardless.

## Response `200`

Search for a ConversionElectrodeDoc

- ResponseConversionElectrodeDoc
  - `data` ConversionElectrodeDoc[], nullable — List of returned data
    - `builder_meta` EmmetMeta — Default emmet metadata.
      - `emmet_version` string, nullable — The version of emmet this document was built with.
      - `pymatgen_version` string, nullable — The version of pymatgen this document was built with.
      - `run_id` string, nullable — The run id associated with this data build.
      - `batch_id` string, nullable — Identifier corresponding to the origin of this document's blessed task.
      - `database_version` string, nullable — The database version for the built data.
      - `build_date` string, date-time, nullable — The build date for this document.
      - `license` 'BY-C' | 'BY-NC', nullable — License for the data entry.
    - `battery_type` string, nullable — The type of battery (insertion or conversion).
    - `material_ids` unknown[], nullable — The ids of all structures that matched to the present host lattice, regardless of stability. The stable entries can be found in the adjacent pairs.
      - unknown
    - `thermo_type` string, nullable — The functional type used to compute the thermodynamics of this electrode document.
    - `battery_formula` string, nullable — Reduced formula with working ion range produced by combining the charge and discharge formulas.
    - `working_ion` string, nullable — The working ion as an Element object.
    - `num_steps` integer, nullable — The number of distinct voltage steps in from fully charge to discharge based on the stable intermediate states.
    - `max_voltage_step` number, nullable — Maximum absolute difference in adjacent voltage steps.
    - `last_updated` string, date-time — Timestamp for the most recent calculation for this Material document.
    - `framework` object, nullable — The chemical compositions of the host framework.
    - `framework_formula` string, nullable — The id for this battery document.
    - `elements` string[], nullable — The atomic species contained in this electrode (not including the working ion).
    - `nelements` integer, nullable — The number of elements in the material (not including the working ion).
    - `chemsys` string, nullable — The chemical system this electrode belongs to (not including the working ion).
    - `formula_anonymous` string, nullable — Anonymized representation of the formula (not including the working ion).
    - `warnings` string[], nullable — Any warnings related to this electrode data.
    - `formula_charge` string, nullable — The chemical formula of the charged material.
    - `formula_discharge` string, nullable — The chemical formula of the discharged material.
    - `max_delta_volume` number, nullable — Volume changes in % for a particular voltage step using: max(charge, discharge) / min(charge, discharge) - 1.
    - `average_voltage` number, nullable — The average voltage in V for a particular voltage step.
    - `capacity_grav` number, nullable — Gravimetric capacity in mAh/g.
    - `capacity_vol` number, nullable — Volumetric capacity in mAh/cc.
    - `energy_grav` number, nullable — Gravimetric energy (Specific energy) in Wh/kg.
    - `energy_vol` number, nullable — Volumetric energy (Energy Density) in Wh/l.
    - `fracA_charge` number, nullable — Atomic fraction of the working ion in the charged state.
    - `fracA_discharge` number, nullable — Atomic fraction of the working ion in the discharged state.
    - `reaction` TypedBalancedReactionDict
      - `@module` string, required
      - `@class` string, required
      - `reactants` object, required
      - `products` object, required
    - `initial_comp_formula` string, nullable — The starting composition for the ConversionElectrode represented as a string/formula.
    - `adj_pairs` ConversionVoltagePairDoc[], nullable — Returns all of the voltage steps material pairs.
      - `formula_charge` string, nullable — The chemical formula of the charged material.
      - `formula_discharge` string, nullable — The chemical formula of the discharged material.
      - `max_delta_volume` number, nullable — Volume changes in % for a particular voltage step using: max(charge, discharge) / min(charge, discharge) - 1.
      - `average_voltage` number, nullable — The average voltage in V for a particular voltage step.
      - `capacity_grav` number, nullable — Gravimetric capacity in mAh/g.
      - `capacity_vol` number, nullable — Volumetric capacity in mAh/cc.
      - `energy_grav` number, nullable — Gravimetric energy (Specific energy) in Wh/kg.
      - `energy_vol` number, nullable — Volumetric energy (Energy Density) in Wh/l.
      - `fracA_charge` number, nullable — Atomic fraction of the working ion in the charged state.
      - `fracA_discharge` number, nullable — Atomic fraction of the working ion in the discharged state.
      - `reaction` TypedBalancedReactionDict
        - `@module` string, required
        - `@class` string, required
        - `reactants` object, required
        - `products` object, required
    - `electrode_object` object, nullable — The Pymatgen conversion electrode object.
  - `errors` Error[], nullable — Any errors on processing this query
    - `code` integer, required — The error code
    - `message` string, required — The description of the error
  - `meta` Meta — Meta information for the MAPI Response.
    - `api_version` string — A string containing the version of the Materials API implementation, e.g. v0.9.5
    - `time_stamp` string, date-time — A string containing the date and time at which the query was executed
    - `total_doc` integer, nullable — The total number of documents available for this query
    - `facet` object, nullable — A dictionary containing the facets available for this query

## Other responses

- `422` — Validation Error

## Changes

> 4 revisions in range; 2 could not be searched.

- **2026-07-26** `9aac4fdf4081` — 1 info
  - the `api_version` response's property default value changed from `0.87.2.dev4+g6bd8ed856` to `0.87.2.dev13+g62063a867` for the status `200`

[Change history](https://skmtc.dev/materialsproject/apis/materials-project-api/changes/materials/conversion_electrodes/get.md)

---

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