Battery Design Module Updates

For users of the Battery Design Module, COMSOL Multiphysics® version 6.1 introduces a new interface for modeling multiple batteries, the ability to simulate heat transfer in battery layers, and the addition of the Parameter Estimation study step. Learn about these updates and more below.

New Battery Pack Interface

A new Battery Pack interface features a one-to-many approach for setting up multiple lumped battery models and connecting them in a 3D geometry. This interface is typically used together with a Heat Transfer interface for modeling thermal pack management. The interface also features thermal events that may be used to study thermal runaway propagation problems. You can see this addition in the new Thermal Runaway Propagation in a Battery Pack model and the existing Thermal Distribution in a Pack of Cylindrical Batteries and Liquid-Cooled Lithium-Ion Battery Pack models.

The COMSOL Multiphysics UI showing the Model Builder with the Voltage Losses node highlighted, the corresponding Settings window, and a battery pack model in the Graphics window. Temperature distribution in a battery pack during thermal runaway.

New Battery Layers Node in Heat Transfer

A new Battery Layers domain node in the Heat Transfer interfaces makes it possible to model heat transfer in the layers of battery cells using a homogenized approach, where the individual layers of the cell do not need to be resolved in the computational mesh. The homogenization of the heat equation is performed through the use of anisotropic thermal conductivity tensors, which are defined based on the configuration of the battery layers and the thermal conductivity in the in-layer and through-layer directions. View this feature in the new Thermal Runaway Propagation in a Battery Pack model and the following existing models:

The COMSOL Multiphysics UI showing the Model Builder with the Battery Layers node highlighted, the corresponding Settings window, and a lithium battery in the Graphics window. The new Battery Layers node used for setting up heat transfer properties of multiple cylindrical batteries. For a spirally wound (cylindrical) layer configuration, the node creates its own multicylindrical coordinate system, used for assigning different through-layer and in-layer thermal conductivities to the layers in the battery cells.

Parameter Estimation Now Included in the Battery Design Module

The Parameter Estimation study step and BOBYQA, Levenberg-Marquardt, and IPOPT optimization solvers are now available with a Battery Design Module license. Parameter estimation is commonly used for determining suitable parameter values for battery models, based on experimental data. The existing Parameter Estimation of a Time-Dependent Lumped Battery model can now be run using a Battery Design Module license only.

The COMSOL Multiphysics UI showing the Model Builder with the Parameter Estimation node highlighted, the corresponding Settings window, and a 1D plot in the Graphics window. Parameter estimation (fitting) of a lumped battery model using experimental voltage data as input.

Improved Continuity Condition on Assembly Pair Boundaries

Assembly pairs are typically used when nonmatching mesh elements are used on each side of a boundary. The need to use assembly pairs may arise when using, for instance, swept meshes in complex 3D geometries. In this version, the Continuity boundary condition for potential dependent variables (for both the electrode and electrolyte phases) of assembly pair boundaries has been significantly improved in terms of its accuracy and numerical stability in the Current Distribution interfaces and the Lithium-Ion and Battery with Binary Electrolyte interfaces.

The COMSOL Multiphysics UI showing the Model Builder with the Identity Boundary Pair node highlighted, the corresponding Settings window, and a jelly roll model in the Graphics window. Nonmatching mesh elements between layers in the Jelly Roll model from the Application Library of the Battery Design Module.

Nonideal Species Activity Coefficients

Version 6.1 introduces functionality for modeling nonideal electrolytes using Debye–Hückel theory. In such electrolytes, even a small variation in concentration — in the millimolar range — may cause measurable changes in quantities such as pH and electrode equilibrium potential. The ability to account for nonideal effects in modeling and simulation is therefore an important addition to the electrochemistry interfaces. In this version, it is now possible to include these effects in the Tertiary Current Distribution, Nernst-Planck and Transport of Diluted Species interfaces. The activity coefficients may be defined using either the Debye-Hückel species activity or user-defined expressions.

Improved Performance of Property Evaluations

The enhanced performance of property evaluations is noticeable in all property computations, such as density and viscosity, as well as for thermodynamic properties like heat capacity and vapor pressure. Models where a significant part of the solution time is spent performing property evaluations can now be solved in as much as 30% less time.

Advanced Chemical Formulas

It is now possible to use more advanced formulas for chemical species and chemical reactions. The enclosing marks (),[], and {} can be used to indicate structural units in the molecular formula in a coordination complex, for example. To improve readability, simplified names can be used in the reaction formula to indicate an entire species or a part of the molecular structure. When reaction balancing is performed, the complete composition and charge are considered.

Improved Functionality for Adding Species to a System

The functionality to search for species in the database and add them to a model has been extended and improved. The species filtered from a search can now be added one at a time using the Enter key. In addition, it is no longer necessary to reset the filter result when a species has been added.

New Tutorial Models

COMSOL Multiphysics® version 6.1 brings several new tutorial models to the Battery Design Module.