# pymatgen.apps.battery package

This package contains all battery-related application classes, including representations of InsertionElectrodes and ConversionElectrodes.

## Submodules

## pymatgen.apps.battery.analyzer module

Analysis classes for batteries.

class BatteryAnalyzer(struct_oxid, working_ion='Li', oxi_override=None)

  Bases: `object`

  A suite of methods for starting with an oxidized structure and determining its potential as a battery.

  Pass in a structure for analysis.

  Parameters:

    - struct_oxid – a Structure object; oxidation states must be assigned for this structure; disordered structures should be OK

    - working_ion – a String symbol or Element for the working ion.

    - oxi_override – a dict of String element symbol, Integer oxidation state pairs. by default, H, C, N, O, F, S, Cl, Se, Br, Te, I are considered anions.

  get_max_capgrav(remove=True, insert=True)

    Give max capacity in mAh/g for inserting and removing a charged ion Note that the weight is normalized to the most ion-packed state, thus removal of 1 Li from LiFePO4 gives the same capacity as insertion of 1 Li into FePO4.

    Parameters:

      - remove – (bool) whether to allow ion removal

      - insert – (bool) whether to allow ion insertion

    Returns:

      max grav capacity in mAh/g

  get_max_capvol(remove=True, insert=True, volume=None)

    Give max capacity in mAh/cc for inserting and removing a charged ion into base structure.

    Parameters:

      - remove – (bool) whether to allow ion removal

      - insert – (bool) whether to allow ion insertion

      - volume – (float) volume to use for normalization (default=volume of initial structure)

    Returns:

      max vol capacity in mAh/cc

  get_removals_int_oxid()

    Returns a set of ion removal steps, e.g. set([1 2 4]) etc. in order to produce integer oxidation states of the redox metals. If multiple redox metals are present, all combinations of reduction/oxidation are tested. Note that having more than 3 redox metals will likely slow down the algorithm.

    Examples

    LiFePO4 will return [1] Li4Fe3Mn1(PO4)4 will return [1, 2, 3, 4]) Li6V4(PO4)6 will return [4, 6]) note that this example is not normalized

    Returns:

      array of integer ion removals. If you double the unit cell, your answers will be twice as large!

  property max_ion_insertion

    Maximum number of ion A that can be inserted while maintaining charge-balance. No consideration is given to whether there (geometrically speaking) are ion sites to actually accommodate the extra ions.

    Returns:

      integer amount of ion. Depends on cell size (this is an ‘extrinsic’ function!)

  property max_ion_removal

    Maximum number of ion A that can be removed while maintaining charge-balance.

    Returns:

      integer amount of ion. Depends on cell size (this is an ‘extrinsic’ function!)

is_redox_active_intercalation(element) → bool

  True if element is redox active and interesting for intercalation materials.

  Parameters:

    element – Element object

## pymatgen.apps.battery.battery_abc module

This module defines the abstract base classes for battery-related classes. Regardless of the kind of electrode, conversion or insertion, there are many common definitions and properties, e.g., average voltage, capacity, etc. which can be defined in a general way. The Abc for battery classes implements some of these common definitions to allow sharing of common logic between them.

class AbstractElectrode(voltage_pairs: tuple[AbstractVoltagePair, ...], working_ion_entry: ComputedEntry, framework_formula: str)

  Bases: `Sequence`, `MSONable`

  An Abstract Base Class representing an Electrode. It is essentially a sequence of VoltagePairs. Generally, subclasses only need to implement three abstract properties: voltage_pairs, working_ion and working_ion_entry.

  The general concept is that all other battery properties such as capacity, etc. are derived from voltage pairs.

  One of the major challenges with representing battery materials is keeping track of the normalization between different entries. For example, one entry might be TiO2 with one unit cell whereas another is LiTi2O4 with two unit cells. When computing battery properties, it is needed to always use a universal reference state otherwise you have normalization errors (e.g., the energy of LiTi2O4 must be divided by two to be compared with TiO2).

  For properties such as volume, mass, or mAh transferred within the voltage pair, a universal convention is necessary. AbstractElectrode can query for extrinsic properties of several different AbstractVoltagePairs belonging to a single charge/discharge path and be confident that the normalization is being carried out properly throughout, even if more AbstractVoltagePairs are added later.

  The universal normalization is defined by the reduced structural framework of the entries, which is common along the entire charge/discharge path. For example, LiTi2O4 has a reduced structural framework of TiO2. Another example is Li9V6P16O58 which would have a reduced structural framework of V3P8O29. Note that reduced structural frameworks need not be charge-balanced or physical, e.g. V3P8O29 is not charge-balanced, they are just a tool for normalization.

  Example: for a LiTi2O4 -> TiO2 AbstractVoltagePair, extrinsic quantities like mAh or cell volumes are given per TiO2 formula unit.

  Developers implementing a new battery (other than the two general ones already implemented) need to implement a VoltagePair and an Electrode.

  voltage_pairs

    Objects that represent each voltage step

    Type:

      tuple[AbstractVoltagePair, …]

  working_ion

    Representation of the working ion that only contains element type

  working_ion_entry

    Representation of the working_ion that contains the energy

    Type:

      ComputedEntry

  framework_formula

    The compositions of one formula unit of the host material

    Type:

      str

  property framework

    The composition object representing the framework.

  framework_formula: str
  get_average_voltage(min_voltage=None, max_voltage=None)

    Average voltage for path satisfying between a min and max voltage.

    Parameters:

      - min_voltage (float) – The minimum allowable voltage for a given step.

      - max_voltage (float) – The maximum allowable voltage allowable for a given step.

    Returns:

      Average voltage in V across the insertion path (a subset of the path can be chosen by the optional arguments)

  get_capacity_grav(min_voltage=None, max_voltage=None, use_overall_normalization=True)

    Get the gravimetric capacity of the electrode.

    Parameters:

      - min_voltage (float) – The minimum allowable voltage for a given step.

      - max_voltage (float) – The maximum allowable voltage allowable for a given step.

      - use_overall_normalization (booL) – If False, normalize by the discharged state of only the voltage pairs matching the voltage criteria. if True, use default normalization of the full electrode path.

    Returns:

      Gravimetric capacity in mAh/g across the insertion path (a subset of the path can be chosen by the optional arguments).

  get_capacity_vol(min_voltage=None, max_voltage=None, use_overall_normalization=True)

    Get the volumetric capacity of the electrode.

    Parameters:

      - min_voltage (float) – The minimum allowable voltage for a given step.

      - max_voltage (float) – The maximum allowable voltage allowable for a given step.

      - use_overall_normalization (booL) – If False, normalize by the discharged state of only the voltage pairs matching the voltage criteria. if True, use default normalization of the full electrode path.

    Returns:

      Volumetric capacity in mAh/cc across the insertion path (a subset of the path can be chosen by the optional arguments)

  get_energy_density(min_voltage=None, max_voltage=None, use_overall_normalization=True)
    Parameters:

      - min_voltage (float) – The minimum allowable voltage for a given step.

      - max_voltage (float) – The maximum allowable voltage allowable for a given step.

      - use_overall_normalization (booL) – If False, normalize by the discharged state of only the voltage pairs matching the voltage criteria. if True, use default normalization of the full electrode path.

    Returns:

      Energy density in Wh/L across the insertion path (a subset of the path can be chosen by the optional arguments).

  get_specific_energy(min_voltage=None, max_voltage=None, use_overall_normalization=True)

    Returns the specific energy of the battery in mAh/g.

    Parameters:

      - min_voltage (float) – The minimum allowable voltage for a given step.

      - max_voltage (float) – The maximum allowable voltage allowable for a given step.

      - use_overall_normalization (booL) – If False, normalize by the discharged state of only the voltage pairs matching the voltage criteria. if True, use default normalization of the full electrode path.

    Returns:

      Specific energy in Wh/kg across the insertion path (a subset of the path can be chosen by the optional arguments)

  get_sub_electrodes(adjacent_only=True)

    If this electrode contains multiple voltage steps, then it is possible to use only a subset of the voltage steps to define other electrodes. Must be implemented for each electrode object.

    Parameters:

      adjacent_only – Only return electrodes from compounds that are adjacent on the convex hull, i.e. no electrodes returned will have multiple voltage steps if this is set true

    Returns:

      A list of Electrode objects

  get_summary_dict(print_subelectrodes=True) → dict

    Generate a summary dict.

    Parameters:

      print_subelectrodes – Also print data on all the possible subelectrodes.

    Returns:

      A summary of this electrode’s properties in dict format.

  property max_delta_volume

    Maximum volume change along insertion.

  property max_voltage

    Highest voltage along insertion.

  property max_voltage_step

    Maximum absolute difference in adjacent voltage steps.

  property min_voltage

    Lowest voltage along insertion.

  property normalization_mass

    Mass used for normalization. This is the mass of the discharged electrode of the last voltage pair.

    Type:

      Returns

  property normalization_volume

    Mass used for normalization. This is the vol of the discharged electrode of the last voltage pair.

    Type:

      Returns

  property num_steps

    The number of distinct voltage steps in from fully charge to discharge based on the stable intermediate states.

  voltage_pairs: tuple[AbstractVoltagePair, ...]
  property working_ion

    Working ion as pymatgen Element object.

  working_ion_entry: ComputedEntry
  property x_charge: float

    The number of working ions per formula unit of host in the charged state.

  property x_discharge: float

    The number of working ions per formula unit of host in the discharged state.

class AbstractVoltagePair(voltage: float, mAh: float, mass_charge: float, mass_discharge: float, vol_charge: float, vol_discharge: float, frac_charge: float, frac_discharge: float, working_ion_entry: ComputedEntry, framework_formula: str)

  Bases: `MSONable`

  An Abstract Base Class for a Voltage Pair.

  voltage

    Voltage of voltage pair.

    Type:

      float

  mAh

    Energy in mAh.

    Type:

      float

  mass_charge

    Mass of charged pair.

    Type:

      float

  mass_discharge

    Mass of discharged pair.

    Type:

      float

  vol_charge

    Vol of charged pair.

    Type:

      float

  vol_discharge

    Vol of discharged pair.

    Type:

      float

  frac_charge

    Frac of working ion in charged pair.

    Type:

      float

  frac_discharge

    Frac of working ion in discharged pair.

    Type:

      float

  working_ion_entry

    Working ion as an entry.

    Type:

      ComputedEntry

  framework_formula

    The compositions of one formula unit of the host material

    Type:

      str

  frac_charge: float
  frac_discharge: float
  property framework: Composition

    The composition object representing the framework.

  framework_formula: str
  mAh: float
  mass_charge: float
  mass_discharge: float
  vol_charge: float
  vol_discharge: float
  voltage: float
  property working_ion: Element

    Working ion as pymatgen Element object.

  working_ion_entry: ComputedEntry
  property x_charge: float

    The number of working ions per formula unit of host in the charged state.

  property x_discharge: float

    The number of working ions per formula unit of host in the discharged state.

## pymatgen.apps.battery.conversion_battery module

This module contains the classes to build a ConversionElectrode.

class ConversionElectrode(voltage_pairs: tuple[AbstractVoltagePair, ...], working_ion_entry: ComputedEntry, framework_formula: str, initial_comp_formula: str)

  Bases: `AbstractElectrode`

  Class representing a ConversionElectrode, since it is dataclass this object can be constructed for the attributes. However, it is usually easier to construct a ConversionElectrode using one of the classmethod constructors provided.

  Attribute:

    voltage_pairs: The voltage pairs making up the Conversion Electrode. working_ion_entry: A single ComputedEntry or PDEntry

    > representing the element that carries charge across the battery, e.g. Li.

    initial_comp_formula: Starting composition for ConversionElectrode represented

      as a string/formula.

  classmethod from_composition_and_entries(comp, entries_in_chemsys, working_ion_symbol='Li', allow_unstable=False)

    Convenience constructor to make a ConversionElectrode from a composition and all entries in a chemical system.

    Parameters:

      - comp – Starting composition for ConversionElectrode, e.g., Composition(“FeF3”)

      - entries_in_chemsys – Sequence containing all entries in a chemical system. E.g., all Li-Fe-F containing entries.

      - working_ion_symbol – Element symbol of working ion. Defaults to Li.

      - allow_unstable – If True, allow any composition to be used as the starting point of a conversion voltage curve, this is useful for comparing with insertion electrodes

  classmethod from_composition_and_pd(comp, pd, working_ion_symbol='Li', allow_unstable=False)

    Convenience constructor to make a ConversionElectrode from a composition and a phase diagram.

    Parameters:

      - comp – Starting composition for ConversionElectrode, e.g., Composition(“FeF3”)

      - pd – A PhaseDiagram of the relevant system (e.g., Li-Fe-F)

      - working_ion_symbol – Element symbol of working ion. Defaults to Li.

      - allow_unstable – Allow compositions that are unstable

  get_sub_electrodes(adjacent_only=True)

    If this electrode contains multiple voltage steps, then it is possible to use only a subset of the voltage steps to define other electrodes. For example, an LiTiO2 electrode might contain three subelectrodes: [LiTiO2 –> TiO2, LiTiO2 –> Li0.5TiO2, Li0.5TiO2 –> TiO2] This method can be used to return all the subelectrodes with some options.

    Parameters:

      adjacent_only – Only return electrodes from compounds that are adjacent on the convex hull, i.e. no electrodes returned will have multiple voltage steps if this is set true

    Returns:

      A list of ConversionElectrode objects

  get_summary_dict(print_subelectrodes=True) → dict

    Generate a summary dict. Populates the summary dict with the basic information from the parent method then populates more information. Since the parent method calls self.get_summary_dict(print_subelectrodes=True) for the subelectrodes. The current method will be called from within super().get_summary_dict.

    Parameters:

      print_subelectrodes – Also print data on all the possible subelectrodes.

    Returns:

      A summary of this electrode’s properties in dict format.

  property initial_comp: Composition

    The pymatgen Composition representation of the initial composition.

  initial_comp_formula: str
  is_super_electrode(conversion_electrode) → bool

    Checks if a particular conversion electrode is a sub electrode of the current electrode. Starting from a more lithiated state may result in a subelectrode that is essentially on the same path. For example, a ConversionElectrode formed by starting from an FePO4 composition would be a super_electrode of a ConversionElectrode formed from an LiFePO4 composition.

class ConversionVoltagePair(voltage: float, mAh: float, mass_charge: float, mass_discharge: float, vol_charge: float, vol_discharge: float, frac_charge: float, frac_discharge: float, working_ion_entry: ComputedEntry, framework_formula: str, rxn: BalancedReaction, entries_charge: Iterable[ComputedEntry], entries_discharge: Iterable[ComputedEntry])

  Bases: `AbstractVoltagePair`

  A VoltagePair representing a Conversion Reaction with a defined voltage. Typically not initialized directly but rather used by ConversionElectrode.

  rxn

    BalancedReaction for the step

    Type:

      BalancedReaction

  voltage

    Voltage for the step

    Type:

      float

  mAh

    Capacity of the step

    Type:

      float

  vol_charge

    Volume of charged state

    Type:

      float

  vol_discharge

    Volume of discharged state

    Type:

      float

  mass_charge

    Mass of charged state

    Type:

      float

  mass_discharge

    Mass of discharged state

    Type:

      float

  frac_charge

    Fraction of working ion in the charged state

    Type:

      float

  frac_discharge

    Fraction of working ion in the discharged state

    Type:

      float

  entries_charge

    Entries representing decompositions products in the charged state. Enumerates the decompositions products at the tieline, so the number of entries will be one fewer than the dimensions of the phase diagram

    Type:

      [ComputedEntry]

  entries_discharge

    Entries representing decompositions products in the discharged state. Enumerates the decompositions products at the tieline, so the number of entries will be one fewer than the dimensions of the phase diagram

    Type:

      [ComputedEntry]

  working_ion_entry

    Entry of the working ion.

    Type:

      ComputedEntry

  entries_charge: Iterable[ComputedEntry]
  entries_discharge: Iterable[ComputedEntry]
  classmethod from_steps(step1, step2, normalization_els, framework_formula)

    Creates a ConversionVoltagePair from two steps in the element profile from a PD analysis.

    Parameters:

      - step1 – Starting step

      - step2 – Ending step

      - normalization_els – Elements to normalize the reaction by. To ensure correct capacities.

      - framework_formula – Formula of the framework.

  rxn: BalancedReaction

## pymatgen.apps.battery.insertion_battery module

This module is used for analysis of materials with potential application as intercalation batteries.

class InsertionElectrode(voltage_pairs: tuple[AbstractVoltagePair, ...], working_ion_entry: ComputedEntry, framework_formula: str, stable_entries: Iterable[ComputedEntry], unstable_entries: Iterable[ComputedEntry])

  Bases: `AbstractElectrode`

  A set of topotactically related compounds, with different amounts of a single element, e.g. TiO2 and LiTiO2, that can be used to define an insertion battery electrode.

  as_dict_legacy()

    Returns: MSONable dict.

  classmethod from_dict_legacy(d)
    Parameters:

      d (dict) – Dict representation.

    Returns:

      InsertionElectrode

  classmethod from_entries(entries: Iterable[ComputedEntry | ComputedStructureEntry], working_ion_entry: ComputedEntry | ComputedStructureEntry | PDEntry, strip_structures: bool = False)

    Create a new InsertionElectrode.

    Parameters:

      - entries – A list of ComputedEntries, ComputedStructureEntries, or subclasses representing the different topotactic states of the battery, e.g. TiO2 and LiTiO2.

      - working_ion_entry – A single ComputedEntry or PDEntry representing the element that carries charge across the battery, e.g. Li.

      - strip_structures – Since the electrode document only uses volume we can make the electrode object significantly leaner by dropping the structure data. If this parameter is set to True, the ComputedStructureEntry will be replaced with a ComputedEntry and the volume will be stored in ComputedEntry.data[‘volume’]. If entries provided are ComputedEntries, must set strip_structures=False.

  property fully_charged_entry

    The most charged entry along the topotactic path.

  property fully_discharged_entry

    The most discharged entry along the topotactic path.

  get_all_entries(charge_to_discharge=True)

    Return all entries input for the electrode.

    Parameters:

      charge_to_discharge – order from most charge to most discharged state? Defaults to True.

    Returns:

      A list of all entries in the electrode (both stable and unstable), ordered by amount of the working ion.

  get_max_instability(min_voltage=None, max_voltage=None)

    The maximum instability along a path for a specific voltage range.

    Parameters:

      - min_voltage – The minimum allowable voltage.

      - max_voltage – The maximum allowable voltage.

    Returns:

      Maximum decomposition energy of all compounds along the insertion path (a subset of the path can be chosen by the optional arguments)

  get_max_muO2(min_voltage=None, max_voltage=None)

    Maximum critical oxygen chemical potential along path.

    Parameters:

      - min_voltage – The minimum allowable voltage.

      - max_voltage – The maximum allowable voltage.

    Returns:

      Maximum critical oxygen chemical of all compounds along the insertion path (a subset of the path can be chosen by the optional arguments).

  get_min_instability(min_voltage=None, max_voltage=None)

    The minimum instability along a path for a specific voltage range.

    Parameters:

      - min_voltage – The minimum allowable voltage.

      - max_voltage – The maximum allowable voltage.

    Returns:

      Minimum decomposition energy of all compounds along the insertion path (a subset of the path can be chosen by the optional arguments)

  get_min_muO2(min_voltage=None, max_voltage=None)

    Minimum critical oxygen chemical potential along path.

    Parameters:

      - min_voltage – The minimum allowable voltage for a given step

      - max_voltage – The maximum allowable voltage allowable for a given step

    Returns:

      Minimum critical oxygen chemical of all compounds along the insertion path (a subset of the path can be chosen by the optional arguments).

  get_stable_entries(charge_to_discharge=True)

    Get the stable entries.

    Parameters:

      charge_to_discharge – order from most charge to most discharged state? Default to True.

    Returns:

      A list of stable entries in the electrode, ordered by amount of the working ion.

  get_sub_electrodes(adjacent_only=True, include_myself=True)

    If this electrode contains multiple voltage steps, then it is possible to use only a subset of the voltage steps to define other electrodes. For example, an LiTiO2 electrode might contain three subelectrodes: [LiTiO2 –> TiO2, LiTiO2 –> Li0.5TiO2, Li0.5TiO2 –> TiO2] This method can be used to return all the subelectrodes with some options.

    Parameters:

      - adjacent_only – Only return electrodes from compounds that are adjacent on the convex hull, i.e. no electrodes returned will have multiple voltage steps if this is set True.

      - include_myself – Include this identical electrode in the list of results.

    Returns:

      A list of InsertionElectrode objects

  get_summary_dict(print_subelectrodes=True) → dict

    Generate a summary dict. Populates the summary dict with the basic information from the parent method then populates more information. Since the parent method calls self.get_summary_dict(print_subelectrodes=True) for the subelectrodes. The current method will be called from within super().get_summary_dict.

    Parameters:

      print_subelectrodes – Also print data on all the possible subelectrodes.

    Returns:

      A summary of this electrode’s properties in dict format.

  get_unstable_entries(charge_to_discharge=True)

    Returns the unstable entries for the electrode.

    Parameters:

      charge_to_discharge – Order from most charge to most discharged state? Defaults to True.

    Returns:

      A list of unstable entries in the electrode, ordered by amount of the working ion.

  stable_entries: Iterable[ComputedEntry]
  unstable_entries: Iterable[ComputedEntry]

class InsertionVoltagePair(voltage: float, mAh: float, mass_charge: float, mass_discharge: float, vol_charge: float, vol_discharge: float, frac_charge: float, frac_discharge: float, working_ion_entry: ComputedEntry, framework_formula: str, entry_charge: ComputedEntry, entry_discharge: ComputedEntry)

  Bases: `AbstractVoltagePair`

  Defines an Insertion Voltage Pair.

  entry_charge: ComputedEntry
  entry_discharge: ComputedEntry
  classmethod from_entries(entry1, entry2, working_ion_entry)
    Parameters:

      - entry1 – Entry corresponding to one of the entries in the voltage step.

      - entry2 – Entry corresponding to the other entry in the voltage step.

      - working_ion_entry – A single ComputedEntry or PDEntry representing the element that carries charge across the battery, e.g. Li.

## pymatgen.apps.battery.plotter module

This module provides plotting capabilities for battery related applications.

class VoltageProfilePlotter(xaxis='capacity', hide_negative=False)

  Bases: `object`

  A plotter to make voltage profile plots for batteries.

  Parameters:

    - xaxis – The quantity to use as the xaxis. Can be either

    - capacity_grav (-) – the gravimetric capacity

    - capacity_vol (-) – the volumetric capacity

    - x_form (-) – the number of working ions per formula unit of the host

    - frac_x (-) – the atomic fraction of the working ion

    - hide_negative – If True only plot the voltage steps above zero.

  add_electrode(electrode, label=None)

    Add an electrode to the plot.

    Parameters:

      - electrode – An electrode. All electrodes satisfying the AbstractElectrode interface should work.

      - label – A label for the electrode. If None, defaults to a counting system, i.e. ‘Electrode 1’, ‘Electrode 2’, …

  get_plot(width=8, height=8, term_zero=True, ax: Axes = None)

    Returns a plot object.

    Parameters:

      - width – Width of the plot. Defaults to 8 in.

      - height – Height of the plot. Defaults to 6 in.

      - term_zero – If True append zero voltage point at the end

      - ax (plt.Axes) – matplotlib axes object. Defaults to None.

    Returns:

      matplotlib axes object.

    Return type:

      plt.Axes

  get_plot_data(electrode, term_zero=True)
    Parameters:

      - electrode – Electrode object

      - term_zero – If True append zero voltage point at the end.

    Returns:

      Plot data in x, y.

  get_plotly_figure(width=800, height=600, font_dict=None, term_zero=True, **kwargs)

    Return plotly Figure object.

    Parameters:

      - width – Width of the plot. Defaults to 800 px.

      - height – Height of the plot. Defaults to 600 px.

      - font_dict – define the font. Defaults to {“family”: “Arial”, “size”: 24, “color”: “#000000”}

      - term_zero – If True append zero voltage point at the end

      - **kwargs – passed to plotly.graph_objects.Layout

  save(filename: str, width: float = 8, height: float = 6) → None

    Save the plot to an image file.

    Parameters:

      - filename (str) – Filename to save to. Must include extension to specify image format.

      - width – Width of the plot. Defaults to 8 in.

      - height – Height of the plot. Defaults to 6 in.

  show(width=8, height=6)

    Show the voltage profile plot.

    Parameters:

      - width – Width of the plot. Defaults to 8 in.

      - height – Height of the plot. Defaults to 6 in.