Points forts de COMSOL Multiphysics^® 6.0

Battery Design Module Updates

For users of the Battery Design Module, COMSOL Multiphysics^® version 6.0 brings an intercalation strain-stress formulation and a predefined porous conductive binder domain for lithium-ion battery modeling, as well as an event sequence for charge/discharge cycles. Learn more about the battery design updates below.

Adsorbing-Desorbing Species

The modeling capabilities of the existing Electrode Surface boundary condition have been expanded with a set of predefined equations that keep track of surface site occupancy and surface concentration of adsorbed species. The new Adsorbing-Desorbing Species section allows you to model the adsorption-desorption kinetics and thermodynamics at electrode surfaces in combination with multistep electrochemical reactions.

The concentration variation in a deformed geometry of a through-hole via after copper deposition.

The new section for definition of adsorption-desorption processes in the Electrode Surface Settings window. The Nonfaradaic Reactions settings include the reaction rate expressions for the adsorption-desorption process.

Stresses and Strains Due to Lithium Intercalation

The intercalation of lithium in electrode materials, such as graphite, causes expansion and contraction of the lithium-ion battery electrode during charge and discharge cycles. These expansions and contractions lead to stresses and strains in the electrodes. Eventually, the stresses and strains may cause cracks in the electrode resulting in the deterioration of a battery's performance. In the Solid Mechanics interface, you can use the new Intercalation Strain feature to estimate the stresses and strains for a given electrode design, and use the estimates to calculate the deterioration and aging of the electrodes over time. You can view this new feature in the Heterogeneous NMC Electrode, Heterogeneous Lithium-Ion Battery tutorial model.

The von Mises stress in a battery electrode's microstructure.

The UI showing the highlighted Intercalation Strain node and its Settings window.

Predefined Porous Conducting Binder Domain

Binders are used in lithium-ion battery electrodes to hold the different electrode materials and current collectors together. The new Porous Conductive Binder feature allows you to assign homogenized properties to the corresponding binding domains, and at the same time define the electrode particles using a highly accurate heterogeneous approach. The Heterogeneous NMC Electrode, Heterogeneous Lithium-Ion Battery tutorial model uses this new feature.

The highlighted Porous Conductive Binder domain node with its corresponding settings and selections in the Graphics window.

Event Sequence for Multistep Charge/Discharge Cycles

When using the Events interface, you now need to only define the states in a cycle (i.e., voltage or current), end condition, or duration of a step in a sequence. The state variables that control the boundary conditions or domain settings in the model are generated automatically, with the corresponding transition between the different states. You can see this new update in the Electrochemical Capacitor with Porous Electrodes tutorial model.

The model tree shows a sequence of a constant current step followed by a constant voltage step, with a rest step at the end. The figure shows three different charge-discharge cycle sequences.

New Lithium-Ion Battery, Deformed Geometry Multiphysics Interface

With the new Lithium-Ion Battery, Deformed Geometry multiphysics interface, you can automatically couple the current density distribution and the deformation of the lithium metal electrode, due to metal deposition and dissolution. The coupling combines the concentration-solution-based electrolyte transport (used in the Newman model) with the functionality for modeling moving meshes, to account for the geometry changes during charge and discharge cycles. You can see this new interface in the Lithium Plating with Deformation tutorial model.

The change in geometry of the lithium electrode, positioned at the bottom in the plots above, shows the growth of the lithium metal electrode thickness.

Porous Slip for the Brinkman Equations Interface

The boundary layer in flow in porous media may be very thin and impractical to resolve in a Brinkman equations model. The new Porous slip wall treatment feature allows you to account for walls without resolving the full flow profile in the boundary layer. Instead, a stress condition is applied at the surfaces, yielding decent accuracy in bulk flow by utilizing an asymptotic solution of the boundary layer velocity profile. The functionality is activated in the Brinkman Equations interface Settings window and is then used for the default wall condition. You can use this new feature in most problems involving subsurface flow described by the Brinkman equations and where the model domain is large.

The flow and concentration field of a porous reactor model.

The Porous slip option is available in the Brinkman Equations interface Settings window.

Heat Transfer in Porous Media

The heat transfer in porous media functionality has been revamped to make it more user friendly. A new Porous Media physics area is now available under the Heat Transfer branch and includes the Heat Transfer in Porous Media, Local Thermal Nonequilibrium, and Heat Transfer in Packed Bed interfaces. All of these interfaces are similar in function, the difference being that the default Porous Medium node within all these interfaces has one of three options selected: Local thermal equilibrium, Local thermal nonequilibrium, or Packed bed. The latter option has been described above and the Local Thermal Nonequilibrium interface has replaced the multiphysics coupling and corresponds to a two-temperature model, one for the fluid phase and one for the solid phase. Typical applications can involve rapid heating or cooling of a porous medium due to strong convection in the liquid phase and high conduction in the solid phase like in metal foams. When the Local Thermal Equilibrium interface is selected, new averaging options are available to define the effective thermal conductivity depending on the porous medium configuration.

In addition, postprocessing variables are available in a unified way for homogenized quantities for the three types of porous media. View the new porous media additions in these existing tutorial models:

• freeze_drying
• frozen_inclusion
• porous_microchannel_heat_sink_optimization
• geothermal_doublet

The options for porous medium types can now be selected from the Porous Medium feature.

Options for defining the effective thermal conductivity in porous media at local thermal equilibrium.

Nonisothermal Reacting Flow

There are now Nonisothermal Reacting Flow multiphysics interfaces that automatically set up nonisothermal reacting flow models. The Reacting Flow multiphysics coupling now includes the option to couple the Chemistry and Heat Transfer interfaces. Using this coupling, the cross-contributions between heat and species equations like enthalpy of phase change or the enthalpy diffusion term are included in the model. The temperature, pressure, and concentration dependence of different quantities and material properties are also automatically accounted for, making it possible to perform heat and energy balance using the corresponding predefined variables.

Temperature distribution in a tubular reactor.

Nonisothermal Flow in Porous Media

The new Nonisothermal Flow, Brinkman Equations multiphysics interface automatically adds the coupling between heat transfer and fluid flow in porous media. It combines the Heat Transfer in Porous Media and Brinkman Equations interfaces.

The tutorial example Free Convection in a Porous Medium makes use of the new nonisothermal flow functionality. Temperature (K) in a porous structure subjected to temperature gradients and subsequent free convection.

Greatly Improved Handling of Porous Materials

Porous materials are now defined in the Phase-Specific Properties table in the Porous Material node. In addition, subnodes may be added for the solid and fluid features where several subnodes may be defined for each phase. This allows for the use of one and the same porous material for fluid flow, chemical species transport, and heat transfer without having to duplicate material properties and settings. View this new update in the NOx Reduction in a Monolithic Reactor tutorial model.

The new Materials node for Porous Material exemplified on a multiscale model of a packed bed.

New and Updated Tutorial Models

COMSOL Multiphysics^® version 6.0 brings new and updated tutorial models to the Battery Design Module.

Heterogeneous NMC Electrode

The von Mises stress in a battery electrode's microstructure.

Application Library Title:
nmc_electrode_heterogenous
Download from the Application Gallery

Homogenizing a Heterogeneous Electrode Model

Lithium concentration and ionic current in a heterogenous NMC electrode.

Application Library Title:
nmc_electrode_homogenization
Download from the Application Gallery

Electrochemical Capacitor with Porous Electrodes

1D tutorial model of the current distribution and electrode utilization in the porous electrodes in an electrochemical capacitor. The Nernst–Planck equations are used to model transport by diffusion and migration of the binary electrolyte, using tortuosity and porosity parameters to derive effective transport parameters for the porous electrodes.

Application Library Title:
electrochemical_capacitor_porous_electrodes
Download from the Application Gallery

Parasitic Reactions in an Electrochemical Capacitor

This model illustrates the effect of oxygen and hydrogen formation and recombination on the performance and self-discharge of an electrochemical capacitor with an aqueous electrolyte.

Application Library Title:
electrochemical_capacitor_side_reactions
Download from the Application Gallery

Lithium Plating with Deformation

Current and potential distribution in the electrolyte with a solid lithium metal electrode (bottom boundary) and a porous counter electrode (upper rectangular domain). Lithium is deposited at the bottom boundary, squeezing the electrolyte and enlarging the small surface defect that is present at the lower boundary at the initial state. By the use of a current-reverse charging scheme, the growth of the metal protrusion can be mitigated.

Application Library Title:
lithium_plating_with_deformation
Download from the Application Gallery