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