1. Research on initiation methods of thermal runaway reaction
EVS-GTR 8th meeting in Washington DC
2015/06/03

2. Topic Sample information _ LFP+NCA
Method to initiate thermal runaway_ Overcharge + nail + heat
Contrast of three methods conducted on the cell level
Discussion on the method to do thermal propagation test on the pack level

3. Sample information Type Capacity Test item Sample A LFP A1# 20.42Ah
Overcharge
A2#
20.26Ah
A3#
20.46Ah
Nail
A4#
20.18Ah
A5#
20.55Ah
Heat
A6#
20.25Ah
Heat(under test)
A7#
20.44Ah ——
A8#
20.23Ah
Sample A

4. Sample information Type Capacity Test item Sample B NCA B1# 29.39Ah
Overcharge
B2#
29.51Ah
B3#
29.22Ah
Nail
B4#
28.92Ah
B5#
29.74Ah
Heat
B6#
28.52Ah
Heat(under test)
B7#
29.29Ah ——
B8#
29.38Ah
Sample B

5. A1# Overcharge test
Method: 100%SOC, 1C charge until thermal runaway happens.
Tmax=308.9℃, vent and leak

6. A2# Overcharge test
Method: 100%SOC, 1C charge until thermal runaway happens.
Tmax=357.4℃, vent and leak

7. B1# Overcharge test
Method: 100%SOC, 1C charge until thermal runaway happens.
Tmax=308.8℃, vent and leak

8. B2# Overcharge test
Method: 100%SOC, 1C charge until thermal runaway happens.
Tmax=96.8℃, explode

9. A3# Nail test Method: Φ5mm steel nail, 20mm/s.
Tmax=126.1℃, vent, leak and smoke

10. A4# Nail test Method: Φ5mm steel nail, 20mm/s.
Tmax=288.0℃, vent, leak and smoke

11. B3# Nail test Method: Φ5mm steel nail, 20mm/s.
Tmax=372.0℃, vent, leak, smoke and fire

12. B4# Nail test Method: Φ5mm steel nail, 20mm/s.
Tmax=411.0℃, vent, leak, smoke and fire

13. A5# Heat test Method: ARC, 60-300℃, 0.02℃/min. 9/14/2018
T1Exotherm=96.56℃;
T2Runaway=244.9℃;
vent, leak;

14. A6# Heat test Method: ARC, 60-300℃, 0.02℃/min. 9/14/2018
T1Exotherm=97.21℃;
T2Runaway=231.0℃;
vent, leak;

15. B5# Heat test Method: ARC, 60-300℃, 0.02℃/min. 9/14/2018
T1Exotherm=93.07℃;
T2Runaway=204.6℃;
vent, leak;

16. B6# Heat test Method: ARC, 60-300℃, 0.02℃/min. 9/14/2018
左下角图中的温度传感器在测试中损坏，温度不可信
T1Exotherm=95.4℃;
T2Runaway=190.1℃;
vent, leak;

17. explosion (Temp. sensor dropped)
Test results
Test item
Maximum temperature
Remark
Sample A
Overcharge
A1#
308.9℃
vent and leakage
A2#
357.4℃
Nail
A3#
126.8℃
vent, leakage and smoke
A4#
288.0℃
Heat
A5#
410.0℃
A6#
325.3℃
Sample B
B1#
308.8℃
B2#
96.8℃
explosion (Temp. sensor dropped)
B3#
372.0℃
vent, leakage and fire
B4#
411.0℃
B5#
315.0℃
B6#
305.2℃

18. Contrast 9/14/2018 Overcharge Nail Heat Thermal runaway temperature
300℃
100℃～400℃
250℃
Test result
Vent and leakage
Smoke or fire
most serious, Vent and leakage or fire
Operational
Better
normal
Good
Successful
Influence factors
Active Protection device, like PTC or CID
Material
Thermal diffusion

19. Discussion
Overcharge, nail and heat can initiate the thermal runway on the cell level;
Which method is the better one to be used for the thermal propagation on the pack level?
China suggests that the method overcharge be a better option based on the test results.

20. Thanks ！