1. Study of Mechanical and Thermal Damage of Lithium Ion Battery Separators
Advanced Manufacturing and Design Laboratory (AMDL)
Douglas Wicker, Mason Pingel, Alex Francis, and Dr. Ilya Avdeev

2. Objective
Courtesy of tesla.com

3. Experiments
Compression of separator

4. Experiments (cont.) Heating of separator
Heat for 1 minute on hot plate
One sample at 110°C and second at 135°C
Temperature verified with thermal imaging camera

5. SEM Images of Separator
15kN
30kN
33.0 MPa
66.0 MPa
Undamaged
45kN
60kN
100.0 MPa
133.0 MPa
110°C
135°C

6. Coin Cell Cycling Procedure (After Formation)
Building Batteries
Coin Cell Cycling Procedure (After Formation)
Charge: 1C charge using mA to 4.1 V
Constant Voltage: hold 4.1 V until current is 0 A
Rest: allow the cell to rest for 1 minute
Discharge: 5C discharge using mA to 2.7 V
Repeat x 200
2023 coin cell (1.475 mAh)

7. Determining 2D Porosity
SEM Image
Processed Image

8. Determining 2D Porosity (cont.)

9. Determining True (3D) Porosity

10. Cycle Life

11. Conclusions
Porosity decreases rapidly at a threshold of damage then continues to decrease slowly with increasing damage
Cycle life and capacity are reduced with decreasing porosity
Porosity of 110°C sample similar to low stress level compressed samples
*mercury intrusion tests were not conclusive
Porosity of 135°C sample similar to high stress level compressed samples

12. Thank You!
Questions / Comments