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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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;

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℃

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

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.

Thanks ！