Selecting the Battery Scale
The first step is to select the Randles circuits modeling scale.
Ansys LS-DYNA offers 4 different solutions to model Randles circuits within a battery cell on different scales and level of detail, as below:
| Modeling scale | Ansys LS-DYNA keyword | Characteristics | Best for |
|---|---|---|---|
| Micro | *EM_RANDLES_SOLID | Detailed modeling of cell layers / Current collector nodes connected by Randles circuits | Single unit cell battery |
| Meso | *EM_RANDLES_TSHELL | Cell layers modelled using composite thick shells / Layer definition required | Detailed analysis of multi unit cell battery |
| Macro | *EM_RANDLES_BATMAC | Unit cell modelled as a uniform solid part / Randles circuits modelled at nodal level | Multiphysics analysis |
| Meshless | *EM_RANDLES_MESHLESS | Models a floating Randles circuit / Battery internal layers not modelled | External short circuit modeling |
The selected modeling scale determines the type and number of parts used per unit cell, the span of the tabs, the tab-cell electrical connection as well as the *EM_RANDLES keyword used to model the Randles circuit within the battery cell.
The selected scale will be highlighted. The structure of a battery unit cell depends on the selected modelling scale as follows:
Micro scale:
- Each unit cell is composed of 5 solid parts defining the battery layers: Positive Current Collector (PCC), Cathode, Separator, Anode, Negative Current Collector (NCC).
- The material and thickness information need to be defined for each layer.
- The positive tab spans the positive current collector and the negative tab spans the negative current collector.
Meso scale:
- Each unit cell is defined as a composite tshell part, and can contain as many layers as required (repetitions of PCC, Cathode, Separator, Anode, NCC).
- The material and thickness information need to be defined for each layer.
- Both positive and negative tabs span the unit cell part.
Macro scale:
- Each unit cell is defined as a single solid part.
- No physical representation of the individual layers.
- Both positive and negative tabs span the unit cell part.
Meshless scale:
- Can be used in solitary state without being connected to any structure (steps 2 and 3 will be skipped), or in conjunction with the Macro scale structure.
- If the Connect to macro scale structure? option is selected then the lumped Randles circuit of meshless type will be defined between the two tabs through the *EM_ISOPOTENTIAL_CONNECT keyword.
Once the Modeling scale is selected, click on Next to move to the second step.