From the pull-down menu Experiment Type, select the appropriate entry to simulate the charging or discharging of the battery cell or set a charging profile. Here, a charging simulation is chosen. For the experiment types Charge Battery Cell and Discharge Battery Cell select the Boundary Conditions in Through Direction and the Start and End Condition. How to Set a Charging Profile is explained here.

The Boundary Conditions in Through Direction can be specified by a Charge Rate, a Current Density, by defining the Current, by defining the Cell Potential, or the Power Density.

• With a Charge Rate defined, the applied current is related to the cell’s maximum capacity from 0% state of charge to 100% state of charge and is a measure of the duration of the battery charging. For example, a charge rate of 1 for a battery with capacity of 1 Ah means that the battery is charged completely in 1 hour with a constant current of 1 Ampere (A). This time is unrelated to the simulation time, but instead to the time that the charging process itself requires. A charge rate of 2 means that charging the same battery with a current of 2 Ampere takes ½ hour.
  

• Defining the Current Density instead means that the applied the applied current density (in A/m²) is defined directly.
  
• Defining the Current instead means that the applied current (in A) is defined directly.
  

• If Cell Potential is selected, the voltage is kept at a constant value during the simulation, and the current is a time-dependent value. Define a Cut-Off Current as end condition.
  
• Defining the Power Density in  W/m² means that the applied current density is dynamically adjusted so that the product of cell potential and current density - i.e., the power density - remains constant throughout the simulation.
  

The Start and End Condition for the charging simulation can be defined in several ways:

• as minimum and maximum percentage of the state of charge of the whole cell (Minimum and Maximum Cell SOC)
  

• for the anode SOC and cathode SOC individually (Anode and Cathode SOCs),
  

• by selecting an initial .cap file from a previous BatteryDict simulation and defining a final SOC (Initial *.cap File and Final Cell SOC). This option is especially useful for simulating a charging or discharging process, starting from a non-equilibrium condition after a previous discharging or charging simulation.
  
• or, by defining an initial voltage value and a final SOC (Initial Voltage and Final Cell SOC). This option can be used together with Use Upper (Lower) Cut-Off Voltage to define a voltage window for your charging (discharging) simulation.
  

Depending on the selected boundary conditions, it is possible to set additional an end conditions to the simulation.

• Limit the voltage in a simulation by checking Use Upper / Lower Cut-Off Voltage. The voltage will not exceed this limit. I.e., if the cut-off voltage is reached, the charging will end. This option is not available for the boundary condition Cell Potential.
  

• If Cell Potential is set as boundary condition in through direction, select the Cut-Off Current as an end condition to the simulation to be Charge Rate, Current Density or Current. For example, consider charging a battery at constant Cell Potential, and selecting a Cut-Off Charge Rate. The simulation starts with the entered SOC value and charges the battery at the provided constant cell potential, for example at 3.5 V. During the charging, the charge rate decreases with the increasing SOC. As soon as the charge rate is lower than the entered Cut-Off Charge Rate, the simulation stops.
  

• When checking Max. Simulated Time, the simulation ends if the charging process exceeds the entered Max. Simulated Time. Note that Max. Simulated Time does not denote the duration given to the solver. Instead it specifies how long the simulated battery is charged or discharged. For an example, let us consider a battery that is charged from 20% state-of-charge to 70% state-of-charge at a charge rate of 1C. The battery takes 30 min to charge. If the Max. Simulated Time is set to 600 seconds (10 min), in this example the battery will only be charged from 20% to 36.67% state-of-charge.
  

Charging Profiles are a series of charging, discharging, and relaxation simulations that are performed sequentially for the same structure.

If Set a Charging Profile is selected as Experiment Type, the starting point for the first simulation can be defined

• as an Equilibrium Cell SOC (Select an initial Cell SOC between 5% and 95%, that defines the initial equilibrium state),
  
• as an Equilibrium Voltage (enter the voltage for the initial equilibrium state of the battery),
  

• or, by selecting a .CAP File of a previous simulation.
  

The starting point for the following simulations, defined in the charging profile table, is always the final state of the previous one.

To define a charging profile, choose as many rows for the table as simulation steps desired by entering the Number of Rows. Select for each step, if the battery is charged, discharged, or if relaxation is simulated.

For charging or discharging, define the Type of Boundary Condition (BC) and the corresponding Applied BC Value, in the same way as for simple charging simulations. The same options for the boundary condition (Charge Rate, Current Density, Current, Cell Potential, and Power Density) are available.

For charging or discharging, next, the first stopping criterion for the selected boundary condition (Stopping Criterion at Boundary) is chosen for each simulation step. The available options depend on the Type of Boundary Condition.

• If Charge Rate, Current Density, Current, or Power Density is selected as BC, only a cut-off Cell Potential is possible as stopping criterion at boundary.
• For Cell Potential as BC, the stopping criterion at boundary can be chosen between a cut-off Charge Rate, Current Density, and Current.

Enter the Stopping BC Value for the first stopping criterion, for the second stopping criterion a stopping state-of-charge for the whole cell (Stopping Cell SOC / %) and for the (optional) third stopping criterion a Stopping Time. The computation ends for each simulation step, if the first one of the stopping criteria is reached. The next simulation step will continue from this state.

For relaxation, no boundary conditions need to be defined, only the stopping time as the only possible stopping criterion of the relaxation step. In a relaxation step, the return of the battery cell to an equilibrium state after charging or discharging is simulated. The solver settings, including the time step, are set by BatteryDict to optimize the simulation time required for the relaxation step.

Periodic or Symmetric boundary conditions can be selected for the Boundary Conditions in Tangential Directions.

For periodic boundary conditions, the structure is assumed to repeat periodically in Y- and Z-direction and for symmetric boundary conditions, the structure is mirrored in Y- and Z-direction and the Li+ ions and electrons are reflected at the boundary in Y- and Z-direction. The connected and unconnected parts of the active materials and electrolyte depend on the boundary conditions, so they are determined when the simulation begins.