1. Motivation:
 Overcharging and over-discharging of lithium-ion battery cells can shorten battery life and cause safety issues. Cells also perform differently with aging conditions. The battery cell impedance can be used to estimate the cell State-of-Charge and cell State-of-Health. However, it takes a long time for cells in each state to be prepared and the cell voltage response during charging and discharging under each condition to be measured. Accurate simulation models eliminate not only the purchase cost of experimental devices, but also the time required for cells to be prepared in different states, and significantly reduce the time required for measurement. 

2. Description:
 An electrical equivalent circuit model of a lithium-ion cell is developed in MATLAB/Simulink. 
The developed model outputs cell impedance through real-time prediction of cell voltage during discharge. 
Output cell voltage and cell impedance from the simulation model takes into account cell SoC, SoH, temperature, and C-rate. 
 This simulation model is suitable for use in cell SoC and cell SoH monitoring studies.

3. Cell_Model_Kim.zip contains the following files:
- Cell_Model_Kim.slx
- templookup.mat

4. Operating instructions:
- Please run the Cell_Model_Kim.slx file on the PC where MATLAB is installed.
- The templateup.mat file must exist in the 'current folder' in MATLAB.
- In the executed Cell_Model_Kim.slx Simulink window, press the Run button.
- When the simulation is completed, the cell voltage, cell impedance, and cell temperature are displayed.

5. Configuration instructions:
- Double-click the DC_offset block to set the DC offset value of the cell to be discharged.
- Double-click the SoC_init block to set the initial SoC value of the cell to be discharged.

* You can change the model properties by right-clicking on Simulink's empty space.
  In InitFcn in the model attribute, you can change the following attributes.:
- To change the sampling rate in the simulation, change the value of the 'sample' variable.
- To change the test amplitude in the simulation, change the value of the 'pa_amp' variable. The unit is A.
- Please set the variable 'pa_freq' to change the first test frequency. The unit is Hz.

* Please follow the instructions below to apply both test frequencies simultaneously.:
- The initial setting is set to apply only one 1 Hz test frequency. 
- To apply one additional test frequency, please change the variable 'nFrequencies' to 2. 
- The second test frequency can be set by the variable 'pa_preq2'. The unit is Hz.
- Please connect the arrow of the 'Test Freq. 2' block of the Simulink window.

6. This simulation model is made by: 
Jonghyeon Kim

7. Please contact me via following E-mail adress: 
jonghyeon.kim@eet.tu-berlin

8. Copyright and licensing information:
Attribution 4.0 International (CC BY 4.0)