SATPC0036227 Tab 04 4 SOW..pdf

Optimizing the Safety of Plastic Current Collector in Cylindrical Li-ion Cells

SOW

25 July 2024

1.0 Objective – To determine if electrode jellyroll fit inside can is a cell design driving factors that limits the safety of plastic current collectors (PCC) in high capacity/energy Li-ion cylindrical cells. Of particular importance is the local compression of the jelly roll. This work will focus on build cells with various amount of compression measured both during JR insertion and after formation via cell tear-down.

2.0 Scope – Design, build, and test Li-ion 21700 cells. Focus first on building cells with cathode PCC in groups of 3-5 cells and perform nail pen. Once a nail pen resistant cell (NPRC) is developed, build suitable control cells without PCC for delivery to NASA with NPRCs. All cells with polycrystalline NMC811 coated on 6µm PET with 1µm Al on both sides, and ceramic coated separator.

3.0 NASA Inputs – Calorimetry with high-speed radiography of cells in thermal runaway along with tomography of surviving cells pre and post.

4.0 Contractor Tasks

4.1 Design Round 1: 3-5 cells per group

Cylindrical Cells - 216 cans/headers

Cell Group Jelly Roll Fit Winding Tension PCC Design Capacity

4.1.0 Group 1.0 Control cells based on NPRCs cell design.

Will be produced at the end of the project.

N

4.1.1 Group 1.1 -1.00 mm Loose Y 4.9 Ah

4.1.2 Group 1.2 -1.00 mm Tight Y 4.9+ Ah

4.1.3 Group 1.3 -0.25 mm Loose Y 4.9+ Ah

4.1.4 Group 1.4 -0.25 Tight Y 4.9+ Ah

4.1.5 Group 1.5 Lessons learned

from previous groups

Y

It is anticipated that additional cell groups may be required.

4.1.1 Group 1.0 - 4.9Ah in 21.6mm diameter can wound with low winding tension with Soteria Al PCC and Cu foil. This cell design will have a loose jellyroll fit relative to cell can and will feature a jelly roll with a jelly roll that is 1.00 mm smaller than the inside can dimension. 3-5 cells will be produced and immediately subjected to nail penetration.

4.1.2 Group 1.1-1.X modifications outlined in the table above. Each additional group of cells will be modified based on weekly meetings with NASA. Up to 20 groups will be produced and subjected to nail pen testing immediately after formation.

4.2 Design Round 1: Pouch Cells

Pouch Cells – 20Ah Cell Group PCC Design

Capacity

4.2.7 Group 2.1 Y 20Ah

4.2.2 Group 2.2 N 20Ah

4.2.1 Group 2.1 – Using the same electrode and separator design as in Group 1.1, build 20Ah pouch cells.

4.2.2 Group 2.2 – Using the same electrode and separator designs as in Group 1.0, the control group without PCC, build 20Ah pouch cells.

4.3 Test – Perform nail penetration on 3-5 cells from each cylindrical cell group (1.0 to 1.X) at 100% SoC. Perform nail penetration on 3-5 cells from groups 2.1 & 2.2 at 100% SoC while wide faces are under stack pressure typically applied for Li-ion batteries using pouch cells.

No more than a ¼” diameter hole shall be allowed for penetration with a 1/8” diameter nail.

5.0 Deliverables

5.1 Data – Cell build plan shall be provided prior to committing to assembly. Cell formation, capacity, and impedance shall be provided prior to shipping and nail penetration testing.

Nail penetration test debriefing. All data shall be provided within 1 week of each testing cycle completion. Team will hold weekly meetings with NASA to review progress towards a NPRC. Design changes in future groups of cells will be decided each week.

5.2 Cells – Cells shall be delivered to NASA-JSC within 4 months after contract start date with minimum quantities specified herein.

5.2.1 During development, many different groups of cells will be produced with 3-5 cells per group. Up to 20 different cell groups may be produced. Work will continue until 20 groups have been produced or a NPRC design is achieved.

5.2.2 If a NPRC group is achieved, Coulometrics will deliver the following to NASA:

5.2.2.1 50 NPRCs that feature the PCC current collector.

5.2.2.2 20 Control cells W/O PCC.