1. EVS-GTR phase 2 Thermal propagation
From China
September,2017

2. Contents
Work achievements in the first stage
Summary of existed problem
Verification test scheme and plan in the second stage
Introduction of battery cell test result

3. Work achievements in the first stage
Initiation
Heat
Nail
Over-charge N
Detection of
Thermal runaway
Initiation Cell
Thermal runaway? N
All three initiations
no thermal runaway? Y
Pass
Voltage drops
dT/dt > [X1oC/s]
T>[OEM defined max temperature] Y
AND
Thermal runaway
Propagation? N
Pass
Hard to judge through
visual observation Y
External fire
or explosion? N
Pass
Easy to judge through
visual observation Y
<X2min after warning signal?
N >X2min
Pass
Easy to judge through
visual observation Y
Fail

4. Summary of existed problem
Existed problems
1.1 all the methods will change the battery system structure
1.2 all the methods may introduce additional energy, that may influence the test results
1.3 the equivalence of the test results with different experimental methods ；
1.4 the thermal runaway condition needs to be further clarified
1.5 no uniform specifications for heating method
1.6 verify the repeatability of test results with the same method and the same sample
1.7 verify the influences for test results with other factors

5. Verification test scheme
1. Research on test method
1.1 additional energy introduced by different method
1.2 test parameters verifying in different trigger methods
1.3 comparison of test results with different trigger methods
2. Repeatability of test results
2.1 Repeatability of test results for the same method
2.2 Verification test between different laboratories
pack thermal propagation evaluation method
Further rationalization of the condition of thermal runaway judgment
Cell thermal runaway trigger method
The differences of three methods to battery systems
Nail
Over charge
heat
Voltage drop
Highest Temperature
Temperature rise rate

6. Verification test scheme
Nail position
Nail
Material：High temperature resistant, stainless steel
Diameter：5mm
Angle：60°
Surface requirements：Smooth, no rust, oxide and oil
Nail speed：25mm/s
Over charge
The trigger method is over charge, the current will be three different rate:1C/2C/3C，over charge the battery until it goes into runaway
Heating
prismatic and pouch cells：
Place the heating devices on the largest plane, and occupy ½ ~4/5 surface area
cylindrical cells：
Heating wire winding the cells, and place the thermal sensors at the negative
Temperature sensor
Temperature sensor
Heating wire

7. Verification test scheme
Trigger method
Nail
Over charge
Heat
Parameters
voltage
 ——
current
power
test time
energy introduced
temperature
Weight before and after test
video
photos
Requirement
data sampling rate of 100Hz

8. Verification test scheme
Type
thermal sensors position
Claps
Illustration
Prismatic
valve（1#）
positive（2#）
negative（3#）
Both sides of nail position（4#、5#） As for over charge and heat, the central of the big plane
Positive side（6#）
Negative side (7#)
Middle of bottom（8#）
YES
Pouch
positive（1#）
negative（2#）
nail position；（3#、4#、5#、6#）
As for over charge and heat, the positions are middle of front and back, and the point farthest from the center(3#、4#、5#、6#）
Cylindrical
nail position（3#） As for overcharge, the middle of side（3#） NO

9. Verification test scheme
The focuses of thermal propagation are
the state of the trigger target cell
the thermal propagation way.
Trigger target
Trigger method
Nail
Over charge
Heat
Parameters
voltage
 ——
current
power
test time
energy introduced
temperature
video
requirement
data sampling rate of 100Hz
data sampling rate of 10Hz
Other cells
1）cell voltages and temperature in the same module
2）2 series cells’ voltages, temperature, and the module voltage in the adjacent modules
3）other modules’ voltage
4）at least 4 temperatures which is farthest from the trigger target

10. Battery cell thermal runaway Battery system thermal propagation
Introduction of test
Battery cell thermal runaway
range
matherial
Type
samples
Energy density
>200
NCM
prismatic
A-48Ah
Cylindrical B
Pouch
J-44Ah
>150~200
Prismatic
L-33Ah
S-2.5Ah C　
100~150
S-26Ah
L2.0Ah M
LFP
B-25Ah
G-22Ah
L-1.6Ah
A-22Ah
50~100
A-6.9Ah D　
LTO
Y-35Ah
J-30Ah
Ni-H
K-8Ah
<50
K-6.5Ah
K-6Ah
Statistics energy density of batteries:
85% samples’ energy densities are 100~200Wh/kg 10 46 39 12 3
Energy density
Battery system thermal propagation
Cell PED
PACK PED
Material
Type
>200
>130
NCM
prismatic
Cylindrical
Pouch
150~200
90-130
Pouch/prismatic
100~150
50-90
NCM/LFP
50~100
<50
LTO
0~50 Wh/kg（3%）
50~100 Wh/kg（11%）
100~150 Wh/kg（35%）
150~200 Wh/kg（42%）
200+ Wh/kg（9%）

11. Same sample, Different method
In the different methods with same samples, the voltage changes consistent, while the temperature varies greatly.
voltage
temperature
NCM
LFP

12. Same samples, Same method
As for same sample and same method, the test repeatability is high.
voltage
temperature
Voltage curve almost same
temperature curve almost same
The highest temperature is same
Current
Max Temperature ℃
Temperature rise rate
℃/s 1C
646.50
507 2C
565.40
429 3C
619.00
472

13. Thanks 13