The AC Impedance, Stationary,
AC Impedance, Time Dependent, and
Cyclic Voltammetry studies are available with the Battery & Fuel Cells Module, Corrosion Module, Electrochemistry Module, or Electrodeposition Module.
The AC Impedance, Initial Values (
) study is used for electrochemical impedance spectroscopy (EIS) computations in electrochemical cells.
The study consists of a single Frequency-Domain Perturbation study step, which solves for a harmonic linear perturbation. Use this study for electrochemical cells when the steady state solution is known a priori. The outputs are Nyquist and Bode plots for selected electrodes over the specified frequency range.
The AC Impedance, Stationary (
) study is used for electrochemical impedance spectroscopy (EIS) computations in electrochemical cells.
The study consists of two study steps: a Stationary study step followed by a
Frequency-Domain Perturbation study step, which solves for a harmonic linear perturbation of the stationary nonlinear solution. The outputs are Nyquist and Bode plots for selected electrodes over the specified frequency range.
The AC Impedance, Time Dependent (
) study is used for electrochemical impedance spectroscopy (EIS) computations in electrochemical cells.
The study consists of two study steps: A Time Dependent study step followed by a
Frequency-Domain Perturbation study step, which solves for an harmonic perturbation of the time-dependent solution at the last time step. This study can be used for systems that do not have a steady solution, for example batteries. The outputs are Nyquist and Bode plots for selected electrodes over the specified frequency range.
The Cyclic Voltammetry (
) study is used for transient computations of voltammetry experiments together with the Electroanalysis interface.
When this study is added, a Cyclic Voltammetry study step is added to the Model Builder. The study step sets up a time-dependent solver. The initial and maximum time step solver settings are based on the settings in the Electroanalysis interface, and a
Stop Condition is added to the solver to stop the simulation at the end of the voltammetry cycling. The settings are described for the
Time Dependent node.
The Stationary with Initialization study is used for stationary electrochemical problems. The study consists of two study steps: a Current Distribution Initialization study step, which solves for the potential fields only, followed by a second stationary study step, for which the field computed by the first study step is used as initial values.
The Time-Dependent with Initialization (
) study can be used to perform transient simulations of electrochemical cells. The study adds a
Current Distribution Initialization study step and
Time Dependent study step to the study node. The Current Initialization step solves for the electrode and electrolyte potentials as well as all global ODE dependent variables. All other dependent variables in the model, such as concentrations and electrode deformation, are set to the initial values in this step. The Time Dependent step performs a transient simulation for all dependent variables in the model, using the result of the first study step as initial values. See the study steps for settings information.
Use the Time-Dependent with Initialization, Fixed Geometry (
) study to exclude geometry deformation effects from a model. The study is similar to the
Time-Dependent with Initialization study, with the difference that the second time-dependent study step does not solve for the geometry deformation dependent variables. This study adds a
Current Distribution Initialization study step and
Time-Dependent, Fixed Geometry study step to the study node. See the study steps for settings information.
The Current Distribution Initialization (
) study step is added to the
Stationary with Initialization;
Time-Dependent with Initialization, Fixed Geometry; and
Time-Dependent with Initialization studies. You can use this study step as an initialization step for the electric and electrolyte potentials in a simulation of an electrochemical cell. The Current Distribution Initialization study step is typically followed by a study step that solves for all dependent variables.
The study step solves for a stationary solution of the potential dependent variables of the model only, which implies that for concentration dependent (tertiary) problems, the concentration will be equal to their corresponding initial while solving this study step. The Current distribution type setting can be set to either
Primary (the default) or
Secondary. If the
Current Distribution type has been set to
Primary (which is the default), potential constraints are used, based on the equilibrium potential of the Electrode Reaction or Porous Electrode Reaction nodes in the Electrochemistry interfaces. Note that this means that if you are using user-defined electrode kinetics expressions, you need to also provide equilibrium potential values for the Current Distribution Initialization to work properly when set to
Primary. Also note that if multiple Electrode Reactions or Porous Electrode Reactions are used on the same boundary/domain, only the equilibrium potential of the first reaction node will be used. The
Primary step will usually result in a linear problem that converges in one iteration only, regardless of the settings of the
Initial Values for the potential variables.
The Secondary setting may need to be used for problems where the ohmic drop in the electrolyte is negligible, such as in cathodic protection, mixed potential, or thin wafer deposition with lateral electronic conduction problems. When using a
Secondary initialization, the
Initial Values settings of the potential values may be crucial for convergence.
The Time-Dependent, Fixed Geometry (
) study step is added to the
Time-Dependent with Initialization, Fixed Geometry study. Use it to exclude the deformation/ALE (
X,
Y,
Z) variables from the variables that are solved for by the study step. This is a suitable study step if you want to simulate a time-dependent electrodeposition or corrosion problem for cases when the mesh deformation is expected to be small. The settings available for this study step are described for the
Time Dependent node.
