Geometries

BattMo supports several battery-cell geometries through the ModelFramework setting. These geometries determine how the electrochemical model is distributed in space, which grids are constructed, and which component-wise outputs are available.

The currently supported geometry families are:

• P2D

• P4D Pouch

• P4D Cylindrical

Overview

Model framework	Cell type	Spatial representation	Typical use
P2D	Through-thickness cell model	1D across the stack, with radial particle diffusion	Fast cell-level studies, parameter sweeps, cycling analysis
P4D Pouch	Pouch cell	3D current-collector / electrode geometry combined with particle diffusion	Tab placement effects, current distribution, pouch thermal/electrical nonuniformity
P4D Cylindrical	Cylindrical / jelly-roll cell	Cylindrical wound-cell geometry combined with particle diffusion	Radial and axial heterogeneity in cylindrical cells

In all three cases, BattMo uses a pseudo-dimensional formulation:

• the electrolyte and solid-phase transport are resolved on the cell geometry

• diffusion inside active-material particles is resolved on a particle-radius coordinate

• component coupling is handled automatically in the assembled multiphysics model

P2D

P2D is the classical Doyle-Fuller-Newman style through-thickness model. The cell is represented as a one-dimensional stack:

• negative electrode

• separator

• positive electrode

If current collectors are enabled, the stack also includes:

• negative current collector

• positive current collector

This is the most efficient option and is usually the right starting point when:

• studying voltage response, concentration profiles, or degradation behavior

• calibrating parameters

• running large parameter sweeps

• current-collector in-plane effects are not important

For P2D, BattMo provides:

• a global through-cell position, output.states["Cell"]["Position"]

• component-wise positions, such as output.states["NegativeElectrode"]["ActiveMaterial"]["Position"]

Main Cell Parameters

Input path	Meaning
["NegativeElectrode"]["Coating"]["Thickness"]	Negative electrode coating thickness.
["PositiveElectrode"]["Coating"]["Thickness"]	Positive electrode coating thickness.
["Separator"]["Thickness"]	Separator thickness.
["NegativeElectrode"]["CurrentCollector"]["Thickness"]	Negative current collector thickness, when current collectors are enabled.
["PositiveElectrode"]["CurrentCollector"]["Thickness"]	Positive current collector thickness, when current collectors are enabled.

Main Simulation Settings

Setting	Meaning
NegativeElectrodeCoatingGridPoints	Number of cells through the negative electrode coating thickness.
PositiveElectrodeCoatingGridPoints	Number of cells through the positive electrode coating thickness.
SeparatorGridPoints	Number of cells through the separator thickness.
NegativeElectrodeParticleGridPoints	Radial resolution inside negative active-material particles.
PositiveElectrodeParticleGridPoints	Radial resolution inside positive active-material particles.
NegativeElectrodeCurrentCollectorGridPoints	Number of cells through the negative current collector thickness.
PositiveElectrodeCurrentCollectorGridPoints	Number of cells through the positive current collector thickness.

P4D Pouch

P4D Pouch resolves the cell in a pouch-cell geometry. The model keeps the pseudo-dimensional electrochemistry, but the cell components are placed on a multi-dimensional spatial grid so that in-plane current and potential variations can be captured.

This geometry is useful when:

• tab placement matters

• current collectors contribute significantly to the cell response

• you want to visualize spatially varying potentials, concentrations, or currents

• nonuniform utilization across the pouch is important

The main components represented are:

• negative current collector

• negative electrode active material / coating

• separator

• electrolyte

• positive electrode active material / coating

• positive current collector

BattMo provides component-wise mesh positions for these domains in the output, for example:

• output.states["NegativeElectrode"]["CurrentCollector"]["Position"]

• output.states["PositiveElectrode"]["ActiveMaterial"]["Position"]

• output.states["Electrolyte"]["Position"]

Main Cell Parameters

Input path	Meaning
["Cell"]["ElectrodeWidth"]	Physical electrode width of the pouch cell.
["Cell"]["ElectrodeLength"]	Physical electrode length of the pouch cell.
["Cell"]["TabWidth"]	Width of the pouch tabs.
["Cell"]["TabLength"]	Length of the pouch tabs.
["Cell"]["TabsOnSameSide"]	Whether positive and negative tabs are placed on the same side of the pouch.
["NegativeElectrode"]["CurrentCollector"]["TabPositionFraction"]	Tab position along the negative current collector width, from 0 to 1.
["PositiveElectrode"]["CurrentCollector"]["TabPositionFraction"]	Tab position along the positive current collector width, from 0 to 1.
["NegativeElectrode"]["Coating"]["Thickness"]	Negative electrode coating thickness.
["PositiveElectrode"]["Coating"]["Thickness"]	Positive electrode coating thickness.
["Separator"]["Thickness"]	Separator thickness.
["NegativeElectrode"]["CurrentCollector"]["Thickness"]	Negative current collector thickness.
["PositiveElectrode"]["CurrentCollector"]["Thickness"]	Positive current collector thickness.

Main Simulation Settings

Setting	Meaning
ElectrodeWidthGridPoints	In-plane grid resolution along pouch width.
ElectrodeLengthGridPoints	In-plane grid resolution along pouch length.
TabWidthGridPoints	In-plane resolution across the pouch tab width.
TabLengthGridPoints	In-plane resolution along the pouch tab length.
NegativeElectrodeCoatingGridPoints	Number of cells through the negative electrode coating thickness.
PositiveElectrodeCoatingGridPoints	Number of cells through the positive electrode coating thickness.
SeparatorGridPoints	Number of cells through the separator thickness.
NegativeElectrodeParticleGridPoints	Radial resolution inside negative active-material particles.
PositiveElectrodeParticleGridPoints	Radial resolution inside positive active-material particles.
NegativeElectrodeCurrentCollectorGridPoints	Number of cells through the negative current collector thickness.
PositiveElectrodeCurrentCollectorGridPoints	Number of cells through the positive current collector thickness.
NegativeElectrodeCurrentCollectorTabWidthGridPoints	Resolution across the negative tab face.
NegativeElectrodeCurrentCollectorTabLengthGridPoints	Resolution along the negative pouch-tab face length.
PositiveElectrodeCurrentCollectorTabWidthGridPoints	Resolution across the positive tab face.
PositiveElectrodeCurrentCollectorTabLengthGridPoints	Resolution along the positive pouch-tab face length.

See also:

• 3D Pouch example

P4D Cylindrical

P4D Cylindrical targets cylindrical cells with a jelly-roll type internal structure. It extends the pseudo-dimensional electrochemistry to a cylindrical geometry so that spatial variations around the wound cell can be represented.

This geometry is useful when:

• modelling cylindrical commercial cells

• studying radial and axial nonuniformities

• investigating tab-driven current distribution

• comparing simplified P2D behavior with a more spatially resolved cylindrical model

As for the pouch case, outputs are provided component-wise for the resolved domains.

Main Cell Parameters

Input path	Meaning
["Cell"]["InnerRadius"]	Inner jelly-roll radius.
["Cell"]["OuterRadius"]	Outer jelly-roll radius.
["Cell"]["Height"]	Axial height of the cylindrical cell.
["NegativeElectrode"]["CurrentCollector"]["TabFractions"]	Angular or spiral placement of one or more negative tabs as fractions of total spiral length.
["PositiveElectrode"]["CurrentCollector"]["TabFractions"]	Angular or spiral placement of one or more positive tabs as fractions of total spiral length.
["NegativeElectrode"]["CurrentCollector"]["TabWidth"]	Width of the negative current-collector tab.
["PositiveElectrode"]["CurrentCollector"]["TabWidth"]	Width of the positive current-collector tab.
["NegativeElectrode"]["Coating"]["Thickness"]	Negative electrode coating thickness.
["PositiveElectrode"]["Coating"]["Thickness"]	Positive electrode coating thickness.
["Separator"]["Thickness"]	Separator thickness.
["NegativeElectrode"]["CurrentCollector"]["Thickness"]	Negative current collector thickness.
["PositiveElectrode"]["CurrentCollector"]["Thickness"]	Positive current collector thickness.

Main Simulation Settings

Setting	Meaning
HeightGridPoints	Number of grid cells along the cylinder height.
AngularGridPoints	Number of angular sectors used around the jelly roll.
NegativeElectrodeCoatingGridPoints	Number of cells through the negative electrode coating thickness.
PositiveElectrodeCoatingGridPoints	Number of cells through the positive electrode coating thickness.
SeparatorGridPoints	Number of cells through the separator thickness.
NegativeElectrodeParticleGridPoints	Radial resolution inside negative active-material particles.
PositiveElectrodeParticleGridPoints	Radial resolution inside positive active-material particles.
NegativeElectrodeCurrentCollectorGridPoints	Number of cells through the negative current collector thickness.
PositiveElectrodeCurrentCollectorGridPoints	Number of cells through the positive current collector thickness.
NegativeElectrodeCurrentCollectorTabWidthGridPoints	Resolution across the negative tab face.
PositiveElectrodeCurrentCollectorTabWidthGridPoints	Resolution across the positive tab face.

See also:

• 3D cylindrical example

Choosing A Geometry

As a rule of thumb:

• use P2D when speed and robust cell-scale trends are most important

• use P4D Pouch for pouch cells with spatially resolved collector/electrode effects

• use P4D Cylindrical for cylindrical cells where wound-cell geometry matters

You select the geometry through the model settings:

model_settings = load_model_settings(; from_default_set = "p4d_pouch")
model = LithiumIonBattery(; model_settings)

or by setting:

model_settings["ModelFramework"] = "P2D"

Related Pages

• Lithium ion model

• Grid parameters

• Simulation output