Configuring a Spiral Cell

You can use Simcenter Battery Design Studio to design spirally wound cylindrical and prismatic cells: the significant difference is the shape of the mandrel around which the cell is wound. In cylindrical cells, the mandrel is a cylinder; in prismatic cells, the mandrel is a geometric prism.

When you create a new spiral cell in Simcenter Battery Design Studio, the battery definition window is displayed in the workspace:

You can use the nodes on the left of the battery window to define characteristics and properties of the battery. You are recommended to start with the default dimensions. However, you can specify the tab configuration and the numerical settings that are used to map data to the thermal mesh in Simcenter STAR-CCM+.

Tab Vertical Alignment

Simcenter STAR-CCM+ supports same-face tabs for spiral cells, that is, battery cell configurations where both the positive and negative tabs are on the same side of the cell.

You can check the vertical alignment of the tabs in the Builders > Detailed node, in the Vertical Alignment tab. The example below shows the default cylindrical spiral cell, in which the tabs have opposite orientation.

If you want to modify the orientation of the tabs, make the appropriate changes in the Vertical tab orientation box.

Tab Type

The default spiral cell has the following tab types defined:

Positive electrode: Coated foil with center tab
Negative electrode: Coated foil with 1 tab on side

However, you can specify a different type for either or both electrodes. To modify the tab type assigned to a particular electrode, select the appropriate node, +Electrode or -Electrode. From the Type drop-down menu, select the new tab type.

If you select a tab type that uses multiple tabs, you need to specify the number of tabs to use.

To specify the number of tabs, in the Fix # tabs box, enter the appropriate number.

Tab Angular Alignment

You can specify the angular alignment of the tabs in the winding. For spiral cells, the tabs are used to orient the local coordinate systems (used for mapping) within the cell. If you do not specify the tab alignment, the local coordinate system origin and the Y-axis (axially along the cell) are defined, but there is no way to define the X-axis and Z-axis of the cell.

The alignment angle is with respect to the mandrel and the zero angle is the positive X-axis. The angle is measured in the anti-clockwise direction for cylindrical cells and the clockwise direction for prismatic cells, as viewed from the positive Y-direction.

In previous versions of Simcenter Battery Design Studio, the tab angle was measured with respect to the start of the electrode. The tab angle is now measured with respect to the mandrel, regardless of the starting point of the electrode.

To align the tabs in the winding, activate the Align tabs in winding box and then, in the Alignment angle, degrees box, specify the angle at which the tabs begin.

You can use the tab alignment setting to specify a particular angle (A_sep) between the tabs. To do this, specify the alignment angles of the tabs in the positive electrode (A_pos) and the negative electrode (A_neg) such that the difference A_pos - A_neg = A_sep.

Number of Spokes

Spokes are used in the discretization of the spiral cell and affect how the cell is wrapped. The number of spokes determine the location on the cell from where the data is mapped to the thermal mesh. You can reduce the number of spokes to speed up calculations or increase it to improve the accuracy of the model.

For a cylindrical cell, you can specify the number of spokes. The default value in the provided cylindrical cell is 50. The range of valid values is 50 - 1000.

To set the number of spokes for a cylindrical cell, select the Builders > Detailed node, and then select the Numerical Settings tab.

In the Number of Spokes box, specify the appropriate number.

If necessary, you can modify the number of spokes value in Simcenter STAR-CCM+, but the same range of valid values applies.

For a prismatic cell, you specify the number of spokes in relation to the size and shape of the mandrel.

To set the number of spokes in a prismatic cell, select the Builders > Detailed node, and then select the Numerical Settings tab.

In the Side Increment box, specify the appropriate value.
The number of spokes on each side of the mandrel is the side length divided by the increment. You can view and modify the mandrel width and thickness in the Winding Stack tab.
In the Corner Angle box, specify the appropriate angle.
The number of spokes on each corner is 90 divided by the specified angle. The minimum value is 10 degrees (9 divisions) and the maximum is 22.5 degrees (4 divisions). If you specify an angle that does not divide evenly into 90, Simcenter Battery Design Studio automatically uses the nearest integral number of spokes.