Batteries & Fuel Cells Module

New Functionality in Version 4.3a

New Physics and Features

• Film Resistance is now available in the Electrolyte-Electrode Boundary Interface and Electrolyte-Electrode Domain Interface features in all Electrochemistry physics (except Primary Current Distribution and Electrode, Shell).

• New Separator domain node in Tertiary Current Distribution, Nernst-Planck physics.

• New liion.cs_average/batbe.cs_average variable introduced, defined by the porous electrode node in the Lithium-Ion Battery and Battery with Binary Electrolyte Interfaces. The variable represents the average solid particle concentration in the electrode particles.

General Improvements and Corrections

• The governing equations for the Porous Electrode feature in Tertiary Current Distribution, Nernst-Planck have been corrected. The time derivative is now multiplied by the electrolyte volume fraction. Also the reaction sources of the Reaction feature are multiplied by the electrolyte volume fraction (that is, implying that the sources correspond to reactions taking place in the fluid phase only). Models created prior to 4.3a with nonunity electrolyte volume fractions will render different results compared to 4.3.

• In the Lithium Ion Battery and the Battery with Binary Electrolyte physics interfaces the transport number variable (tplus) is now correctly assigned to the value in the Materials node, if From material has been chosen for this parameter. The Batteries And Fuel Cells material library value for tplus for the three lithium-ion electrolytes has been changed to 0.363. A space-dependent tplus is now supported.

Updated Model

• SEI layer resistance increase has been added to the “Capacity Fade of a Li-ion Battery” (capacity_fade) model.

Backward Compatibility vs. 4.3

Brinkman Equations and Free and Porous Media Flow

The momentum equations in the Brinkman Equations interface and the Free and Porous Media Flow interface have been corrected. The term -Q_br·u/ε_p² in the right hand side previously lacked the factor 1/ε_p² , where ε_p is the porosity.

Reacting Flow Interface Name Change

The Reacting Flow interfaces have been renamed Reacting Flow in Porous Media. Opening a model using either the Reacting Flow, Diluted Species or the Reacting Flow, Concentrated Species interface, the interface is renamed Reacting Flow in Porous Media.

Weak Constraints Update for Fluid Flow Interfaces

The weak constraint formulation for some boundary conditions in the following interfaces have been updated:

• Laminar Flow

• Brinkman Equations

• Free and Porous Media Flow

See CFD Module for details.

Mobility

In physics user interfaces modeling migration (Transport of Diluted Species, Transport of Concentrated Species, Reacting Flow in Porous Media, Diluted Species, Reacting Flow in Porous Media, Concentrated Species, Tertiary Current Distribution, and Nernst-Planck) anisotropic mobility is now supported, and the mobility can be set to following the Nernst-Einstein relation. The default setting when making new models has been changed to use the Nernst-Einstein relation. Model Java-files generated prior to 4.3a using Migration will have to be modified manually to account for these changes.