solid power 2 ah solid-state battery cell abuse …

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SOLID POWER 2 AH SOLID-STATE BATTERY CELL

ABUSE TESTING – OVERCHARGE

Final Report

SwRI® Project No. 03.26276.05

Prepared for:

Solid Power

486 S. Pierce Ave., Suite E

Louisville, CO 80027

Prepared by:

Mr. Christopher Kelly, Research Engineer

Southwest Research Institute

6220 Culebra Road

San Antonio, TX 78238

October 11, 2021

Approved by:

Dr. Terry Alger, Director

Automotive Propulsion Systems Dept.

POWERTRAIN ENGINEERING DIVISION

This report shall not be reproduced, except in full, without the written approval of Southwest Research Institute®.

Results and discussion given in this report relate only to the test items described in this report.

SwRI® Project No. 03.26276.05 Final Report 2

TABLE OF CONTENTS

1.0 EXECUTIVE SUMMARY............................................................................................................. 4

2.0 PROJECT OBJECTIVES .............................................................................................................. 4

3.0 REFERENCE STANDARDS AND SPECIFICATIONS ............................................................ 4

4.0 TEST EQUIPMENT ....................................................................................................................... 5

5.0 OVERCHARGE TESTING (SET 1) ............................................................................................. 5

5.1 TEST DESCRIPTION ........................................................................................................................ 5 5.2 TEST RESULTS ............................................................................................................................... 6 5.3 CONCLUSIONS ............................................................................................................................. 11

6.0 OVERCHARGE TESTING (SET 2) ........................................................................................... 12

6.1 TEST DESCRIPTION ...................................................................................................................... 12 6.2 TEST RESULTS ............................................................................................................................. 13 6.3 CONCLUSIONS ............................................................................................................................. 17


LIST OF FIGURES

Figure 1: Test Configuration – Overcharge Set 1 ........................................................................... 6 Figure 2: Test 1.1: Pre-test (Left) and Post-test (Right) .................................................................. 6 Figure 3: Test 1.2: Pre-test (Left) and Post-test (Right) .................................................................. 7 Figure 4: Test 1.3: Pre-test (Left) and Post-test (Right) .................................................................. 7 Figure 5: Test 1: Current - Overcharge ........................................................................................... 9 Figure 6: Test 2: Current - Overcharge ........................................................................................... 9 Figure 7: Test 3: Current - Overcharge ......................................................................................... 10 Figure 8: Test 1: Temperatures - Overcharge ............................................................................... 10 Figure 9: Test 2: Temperatures - Overcharge ............................................................................... 11 Figure 10: Test 3: Temperatures – Overcharge............................................................................. 11 Figure 11: Test Configuration – Overcharge Set 2 ....................................................................... 12 Figure 11: Test 1.1: Pre-test (Left) and Post-test (Right).............................................................. 13 Figure 12: Test 1.2: Pre-test (Left) and Post-test (Right).............................................................. 13 Figure 13: Test 1.3: Pre-test (Left) and Post-test (Right).............................................................. 13 Figure 14: Test 1: Current - Overcharge ....................................................................................... 15 Figure 15: Test 2: Current - Overcharge ....................................................................................... 15 Figure 16: Test 3: Current – Overcharge ...................................................................................... 16 Figure 17: Test 1: Temperatures - Overcharge ............................................................................. 16 Figure 18: Test 2: Temperatures - Overcharge ............................................................................. 17 Figure 19: Test 3: Temperatures – Overcharge............................................................................. 17

LIST OF TABLES

Table 1: Test Articles ...................................................................................................................... 4 Table 2: Equipment Used for Testing ............................................................................................. 5 Table 3: Battery Cell OCV Test Record ......................................................................................... 7 Table 4: Maximum Temperature Test Record - Overcharge .......................................................... 8 Table 5: Battery Cell OCV Test Record ....................................................................................... 14 Table 6: Maximum Temperature Test Record - Overcharge ........................................................ 14


1.0 EXECUTIVE SUMMARY

This report describes the test setup and test results obtained during lithium-ion battery

system regulatory assessment testing for Solid Power, Inc. Testing involved parameters from the

SAE J2464 regulation and was conducted in accordance with the Solid Power Statement of Work

provided to SwRI. Three solid-state 2 Ah battery cells were provided to SwRI for overcharge

testing. All testing was conducted on the SwRI campus.

2.0 PROJECT OBJECTIVES

The objective of this testing is to determine whether the Solid Power battery cells meet the

regulations outlined in SAE J2464, Electric and Hybrid Electric Vehicle Rechargeable Energy

Storage System (RESS) Safety and Abuse Testing.

TABLE 1: TEST ARTICLES

Battery Cell

ID Prefix

Battery Cell

Number Test Capacity (Ah) DC Resistance (Ohm)

NSA002210817 11 Overcharge 4 2.149 0.135

NSA002210817 08 Overcharge 5 2.197 0.142

NSA002210817 12 Overcharge 6 2.133 0.130

NSA002210817 04 Overcharge 7 2.191 0.132

NSA002210817 07 Overcharge 8 2.183 0.145

NSA002210817 18 Overcharge 9 2.177 0.151

3.0 REFERENCE STANDARDS AND SPECIFICATIONS

The SAE J2464, Electric and Hybrid Electric Vehicle Rechargeable Energy Storage

System (RESS) Safety and Abuse Testing.


4.0 TEST EQUIPMENT

Test equipment used to perform the tests and acquire data during this testing program is

listed in the table below. NIST-traceable instrumentation calibration is performed in accordance

with the SwRI Operating Procedure listed in the Reference Standards and Specifications section.

Calibration is performed on an annual basis unless otherwise indicated. Calibration is not required

(CNR) for items that are reference only or where the quality critical measurement is made using

other instrumentation listed in the table.

TABLE 2: EQUIPMENT USED FOR TESTING

DESCRIPTION MANUFACTURER MODEL ASSET NO. DUE DATE

Multimeter Fluke 83 III 027073 5/5/2022

Temperature Chamber CSZ ZPHS-16-6-

SCT/AC ZP1042512 CNR

Current Sensor Fluke 80i-110s 027341 9/17/2021

Scale Sartorius U 4100 S 001526 10/29/2021

5.0 OVERCHARGE TESTING (SET 1)

5.1 Test Description

The Solid Power 2 Ah battery cell was tested in accordance with the overcharge criteria of

SAE J2464. The testing precondition involved heating the battery cells for 3 hours at 45 °C, and

then battery cells were charged at a constant current of 0.2 A until battery cell voltage reached 4.2

V. The battery cell was subjected to an overcharge condition at ambient temperature on the top

surface of the DUT. For this set of testing, the battery cells were tested within clamped holders to

maintain compression during the tests. The test procedure called for the device to be charged at 1

C-rate constant current. Charging continued until a voltage of 15 V was reached or until the charge

throughput completed during the overcharge test reached 2 Ah. Test ended if thermal runaway was

detected. Battery cells were safely discharged following each test.


Figure 1 below shows the configuration of the test setup for this portion of testing.

FIGURE 1: TEST CONFIGURATION – OVERCHARGE SET 1

5.2 Test Results

The Solid Power battery cells were subjected to the 4.5.1.2: Overcharge Test in accordance

with SAE J2464. Testing was performed on three (3) battery cells provided by Solid Power as

identified in Table 1.

FIGURE 2: TEST 1.1: PRE-TEST (LEFT) AND POST-TEST (RIGHT)




The visual inspection of the test articles following the exposure revealed no apparent

physical damage to the battery cells because of the test. The pre- and post-test OCV measurements

for each of the three test articles are listed in the table below. All three tests had a slight increase

in voltage, gaining 0.319 V, 0.378 V, and 0.354 V, respectively.

TABLE 3: BATTERY CELL OCV TEST RECORD

Sample Pre-T1

OCV (V)

Post-T4

OCV (V)

Voltage Gain

(V)

1 4.106 4.425 0.319

2 4.102 4.480 0.378

3 4.133 4.487 0.354


Figures 5 - 7 below show current and voltage versus time for each test. Each test was run

for an hour (3600 seconds) and was overcharged with a current of 2 A. Tests 1, 2, and 3 show the

full 2 Ah charge throughput completed, and during that period the voltage increased. All three tests

started at about 4.1 V, and once overcharging began the voltage increased almost instantaneously

by a little less than a tenth of a volt. Following a voltage drop, the voltage for all three tests climbed

steadily for 45 minutes before reaching a plateau. Test 1 has a slight anomaly about 250 seconds

into the test. The current for the overcharge supplied by a Bitrode battery cell cycler had a brief

five-second pause due to operational error. Towards the end of each test, it is possible that an

internal short circuit in the battery cells caused rising temperatures.

In terms of temperatures, each test started around room temperature between 20 ˚C and

25 ˚C. All three tests have similar temperature profiles throughout the testing, with all reaching

between 32 ˚C and 36 ˚C. Table 4 below records the highest temperature reached during each test.

TABLE 4: MAXIMUM TEMPERATURE TEST RECORD - OVERCHARGE

Test

Maximum

Temperature (°C)

1 35.6

2 34.5

3 32.8


FIGURE 5: TEST 1: CURRENT - OVERCHARGE




FIGURE 8: TEST 1: TEMPERATURES - OVERCHARGE



FIGURE 10: TEST 3: TEMPERATURES – OVERCHARGE

5.3 Conclusions

The maximum temperature observed during the tests was 35.6 °C. Final OCV values after

all testing are listed in Table 3, with all three tests showing similar voltage differences. All three

batteries resulted in a Hazard Severity Level of 2, as outlined in SAE J2464 regulation. No venting,

rupture or fire occurred during testing.


6.0 OVERCHARGE TESTING (SET 2)


The Solid Power 2 Ah battery cell was tested in accordance with the overcharge criteria of

SAE J2464. The testing precondition involved heating the battery cells for 3 hours at 45 °C, and

then the battery cells were charged at a constant current of 0.2 A until battery cell voltage reached

4.2 V. The battery cell was subjected to an overcharge condition at ambient temperature on the top

surface of the DUT. For this set of testing, the battery cells were removed from holders during the

tests. The test procedure called for the device to be charged at 1 C-rate constant current. Charging

continued until a voltage of 15 V was reached or until the charge throughput completed during the

overcharge test reached 2 Ah. The test was ended if thermal runaway was detected. Battery cells

were safely discharged following each test.

FIGURE 11: TEST CONFIGURATION – OVERCHARGE SET 2


6.2 Test Results

The Solid Power battery cells were subjected to the 4.5.1.2: Overcharge Test in accordance









for each of the four test articles are listed in the table below. All three tests had a slight increase in

voltage, gaining 0.360 V, 0.370 V, and 0.406 V, respectively.


Sample Pre-T1

OCV (V)

Post-T4

OCV (V)

Voltage Gain

(V)

1 4.110 4.470 0.360

2 4.100 4.470 0.370

3 4.051 4.457 0.406

Figures 14 - 16 below show current and voltage versus time for each test. Each test was

run for an hour (3600 seconds) and is overcharged with a current of 2 A. All three tests show the

full 2 Ah charge throughput completed, and during that the voltage increases. All three tests had

an immediate increase in voltage prior to a voltage drop. This is likely due to an internal short in

the battery cell. At nearly 4.8 V, Test 2 has the highest voltage reached of these tests. An internal

short often can produce an increase in temperature which can be observed in the temperature data

shown in Figure 17 - Figure 19. The current for the overcharge is supplied by a Bitrode battery

cell cycler, which was reporting a 2 A output during the test.


25 ˚C. Test 1 and 3 showed good agreement in temperature increase during the overcharging, with

Test 1 reaching temperatures of about 50 ˚C, and Test 3 reaching temperatures of about 49 ˚C.

Test 2 had an increase in temperature to almost 70 ˚C. Table 6 below records the highest

temperature reached during each test.

TABLE 6: MAXIMUM TEMPERATURE TEST RECORD - OVERCHARGE

Test

Maximum

Temperature (°C)

1 49.5

2 69.2

3 49.0


FIGURE 16: TEST 3: CURRENT – OVERCHARGE




FIGURE 19: TEST 3: TEMPERATURES – OVERCHARGE

6.3 Conclusions

The maximum temperature observed during the three tests was 69.2 °C. Final OCV values

after all testing are listed in Table 3, with the first two tests showing similar voltages to the starting

voltage, and the third test showing the highest voltage increase at 0.406 V. All three batteries

resulted in a Hazard Severity Level of 2, as outlined in SAE J2464 regulation. No venting, rupture

or fire occurred.



ABUSE TESTING – PENETRATION

Final Report


Prepared for:

Solid Power



Prepared by:



6220 Culebra Road


October 11, 2021

Approved by:







TABLE OF CONTENTS




4.0 TEST EQUIPMENT ....................................................................................................................... 5

5.0 PENETRATION TESTING........................................................................................................... 5

5.1 TEST DESCRIPTION ........................................................................................................................ 5 5.2 TEST RESULTS ............................................................................................................................... 5 5.3 CONCLUSIONS ............................................................................................................................... 9


LIST OF FIGURES

Figure 1: Test 1.1: Pre-test (Left) and Post-test (Right) .................................................................. 6 Figure 2: Test 1.2: Pre-test (Left) and Post-test (Right) .................................................................. 6 Figure 3: Test 1.3: Pre-test (Left) and Post-test (Right) .................................................................. 6 Figure 4: Test Configuration – Penetration ..................................................................................... 7 Figure 5: Test 1: Temperatures – Penetration ................................................................................. 8 Figure 6: Test 2: Temperatures – Penetration ................................................................................. 8 Figure 7: Test 3: Temperatures – Penetration ................................................................................. 9

LIST OF TABLES

Table 1: Test Articles ...................................................................................................................... 4 Table 2: Equipment Used for Testing ............................................................................................. 5 Table 3: Battery Cell OCV Test Record ......................................................................................... 7 Table 4: Maximum Temperature Test Record - Penetration .......................................................... 8





SAE J2464 regulation and was conducted in accordance with the Solid Power Statement of Work

provided to SwRI. Three solid-state 2 Ah battery cells were provided to SwRI for penetration

testing. All testing was conducted on the SwRI campus.


The objective of this testing is to determine whether the Solid Power battery cells meet the

regulations outlined in SAE J2464, Electric and Hybrid Electric Vehicle Rechargeable Energy



Battery Cell

ID Prefix

Battery Cell

Number

Test Capacity (Ah) DC Resistance (Ohm)

NSA002210707 8 Penetration 1 2.202 0.192

NSA002210707 16 Penetration 2 2.224 0.180

NSA002210707 20 Penetration 3 2.236 0.176





4.0 TEST EQUIPMENT













5.0 PENETRATION TESTING


The Solid Power 2 Ah battery cells were tested in accordance with the penetration criteria

of SAE J2464. The testing precondition involved heating the battery cells for three hours at

45 °C. Then the battery cell is charged with constant current at 0.2 A until battery cell voltage

reaches 4.2 V. Battery cell OCV is then monitored for one hour. The testing procedure involves

placing the battery cell in a holder and penetrating fully through the battery cell with a conductive

nail at a speed greater than 8 cm/s. The purpose of this test is to simulate an accidental penetration

of the battery cell wall. Hazard severity level is analyzed according to the SAE J2464 test standard

descriptions.

5.2 Test Results

The Solid Power battery cells were subjected to the 4.3.3: Penetration Test in accordance







The three batteries were placed in a battery cell holder within a fire-safe chamber.

Thermocouples were placed on the exterior of the battery cell and the terminals were connected to

a voltage sense line. The test configuration is shown below in Figure 4.

The pre- and post-test OCV measurements for each of the three test articles are listed in

the table below. The first two tests show minimal voltage loss, with the voltage dropping about

0.2 V in each case. The third test had more voltage loss, with a reduction of about 1.3 V.



Sample Pre-Test

OCV (V)

Post-Test

OCV (V)

Reduction

(V)

1 4.092 3.875 -0.22

2 4.110 3.850 -0.26

3 4.111 2.785 -1.33

Figures 5 through 7 display the temperature and voltage versus time results. In each of the

three tests, it can be observed that a slight drop in voltage occurred right after penetration. A short

circuit may have been created causing a slight drop in voltage, but almost immediately the short

circuit went away. The voltage came back to about 4 V, and from there slightly declined over the

course of the rest of the test.


23 ˚C. Once penetration began, all temperatures in each test rose by approximately two degrees

centigrade, and from there continue increasing slightly throughout the test. Table 4 below shows

the highest temperature reached during each test. On Test 1, all the thermocouples read

temperatures that are roughly similar. However, on tests two and three, Thermocouples 3 and 4

read temperatures at least 1 ˚C higher than Thermocouples 1 and 2. This is due to these

thermocouples being closer to the penetration location, which created a short circuit during the test

and thus an increase in temperature in this area.

FIGURE 4: TEST CONFIGURATION – PENETRATION


TABLE 4: MAXIMUM TEMPERATURE TEST RECORD - PENETRATION

Test Maximum

Temperature (°C)

1 25.1

2 26.3

3 27.1

FIGURE 5: TEST 1: TEMPERATURES – PENETRATION




5.3 Conclusions

The maximum temperature observed during any of the tests was 27.1 °C. Final OCV values

after all testing was completed are listed in Table 3, with the first two tests showing a voltage

reduction of about 0.2 V, and the third test showing more of a reduction at 1.33 V. All three tests

resulted in a Hazard Severity Level of 2, as outlined in SAE J2464 regulation. There was damage

to the batteries, with irreversible loss of function; however, no venting, rupture or fire occurred.



ABUSE TESTING – SHORT CIRCUIT

Final Report


Prepared for:

Solid Power



Prepared by:



6220 Culebra Road


October 11, 2021

Approved by:







TABLE OF CONTENTS




4.0 TEST EQUIPMENT ....................................................................................................................... 5

5.0 TEST GROUP 1 – SHORT CIRCUIT TESTING WITH 100 MΩ ............................................ 5

5.1 TEST DESCRIPTION ........................................................................................................................ 5 5.2 TEST RESULTS ............................................................................................................................... 6 5.3 CONCLUSIONS ............................................................................................................................... 9

6.0 TEST GROUP 2 – SHORT CIRCUIT TESTING WITH 500 MΩ .......................................... 10

6.1 TEST DESCRIPTION ...................................................................................................................... 10 6.2 TEST RESULTS ............................................................................................................................. 10 6.3 CONCLUSIONS ............................................................................................................................. 14


LIST OF FIGURES

Figure 1: Test Configuration – Short Circuit with 100 mΩ ............................................................ 6 Figure 2: Test 1.1: Pre-test (Left) and Post-test (Right) .................................................................. 6 Figure 3: Test 1.2: Pre-test (Left) and Post-test (Right) .................................................................. 7 Figure 4: Test 1.3: Pre-test (Left) and Post-test (Right) .................................................................. 7 Figure 5: Test 1.1: Temperatures – Short Circuit with 100 mΩ ..................................................... 8 Figure 6: Test 1.2: Temperatures – Short Circuit with 100 mΩ ..................................................... 9 Figure 7: Test 1.3: Temperatures – Short Circuit with 100 mΩ ..................................................... 9 Figure 8: Test Configuration – Short Circuit with 500 mΩ .......................................................... 10 Figure 9: Test 2.1: Pre-test (Left) and Post-test (Right) ................................................................ 11 Figure 10: Test 2.2: Pre-test (Left) and Post-test (Right).............................................................. 11 Figure 11: Test 2.3: Pre-test (Left) and Post-test (Right).............................................................. 11 Figure 12: Test 2.1: Temperatures – Short Circuit with 500 mΩ ................................................. 13 Figure 13: Test 2.2: Temperatures – Short Circuit with 500 mΩ ................................................. 13 Figure 14: Test 2.3: Temperatures – Short Circuit with 500 mΩ ................................................. 13

LIST OF TABLES

Table 1: Test Articles ...................................................................................................................... 4 Table 2: Equipment Used for Testing ............................................................................................. 5 Table 3: Battery Cell OCV Test Record – 100 mΩ Group ............................................................. 7 Table 4: Maximum Temperature – Short Circuit with 100 mΩ ..................................................... 8 Table 5: Battery Cell OCV Test Record – 500 mΩ Group ........................................................... 12 Table 6: Maximum Temperature – Short Circuit with 500 mΩ ................................................... 12





SAE J2464 test standard and was conducted in accordance with the Solid Power Statement of

Work provided to SwRI. Three solid-state 2 Ah battery cells were provided to SwRI for short

circuit testing. All testing was conducted on the SwRI campus.


The objective of this testing is to determine whether the Solid Power battery cells met the

standards outlined in SAE J2464, Electric and Hybrid Electric Vehicle Rechargeable Energy



Battery Cell

ID Prefix

Battery Cell

Number

Test Capacity (Ah) DC Resistance (Ohm)

NSA002210707 14 1 2.201 0.188

NSA002210707 24 2 2.200 0.181

NSA002210707 25 3 2.238 0.183

NSA002210707 13 4 2.269 0.177

NSA002210707 7 5 2.233 0.186

NSA002210707 5 6 2.166 0.198





4.0 TEST EQUIPMENT













Digital Milliohm Meter Amprobe MO-100 025747 5/5/2022

5.0 TEST GROUP 1 – SHORT CIRCUIT TESTING WITH 100 mΩ


The Solid Power 2 Ah battery cell was tested in accordance with the short circuit criteria

of SAE J2464. The testing precondition involved heating the battery cell for three hours at 45 °C,

and then battery cells were charged at a constant current 0.2 A until battery cell voltage reached

4.2 V. The battery cell was then placed into a pressure chamber for safety, with the pressure kept

at ambient pressure. A short circuit with a 100 mΩ resistance condition at ambient temperature as

measured on the top surface of the Device Under Test (DUT) was then applied and maintained for

60 minutes. The test ended if thermal runaway was detected. Figure 1 below shows the

configuration of the test setup for this portion of testing.


FIGURE 1: TEST CONFIGURATION – SHORT CIRCUIT WITH 100 mΩ

5.2 Test Results

The Solid Power battery cells were subjected to the 4.5.1: Short Circuit Test in accordance







The visual inspection of the test articles following the tests revealed no apparent physical

damage to the battery cells. The pre- and post-test OCV measurements for each of the three test

articles are listed in the table below. All three tests had a decrease in voltage, losing 1.385 V, 1.205

V, and 1.23 V, respectively.

TABLE 3: BATTERY CELL OCV TEST RECORD – 100 mΩ GROUP

Sample Pre

OCV (V)

Post

OCV (V)

Reduction

(V)

1 4.087 2.702 1.385

2 4.095 2.890 1.205

3 4.090 2.860 1.23

Figures 5-7 below show temperature and voltage versus time for each test. Each test ran

for an hour (3600 seconds). Figures 5 and 7 show a voltage trace that is expected for a short circuit

test. The voltage started at 4.2 V, but once the short circuit was applied the voltage first drops

down to about 2 V and then drops down to 0 V. At the end of the short circuit test, the short circuit

is removed causing the battery cell voltage to increase. The ending voltage is reduced due to the


short circuit test, with both Figures 5 and 7 ending at 2.5 V. Figure 6 shows similar results;

however, the front part of the data is cut off due to a data acquisition error.

The temperatures for each test begin at ambient conditions, around 23 . Once the short

circuit is applied, the temperatures began to increase to a maximum level with the values shown

in Table 4 below. As the short circuit continued, more current ran through the system and the state

of charge for the battery cell drops. Over time, this caused the temperature to decrease slowly. At

the end of the test, the temperatures decreased from their max level down to approximately 30 .

TABLE 4: MAXIMUM TEMPERATURE – SHORT CIRCUIT WITH 100 mΩ

* Test 2 shows similar results; however, the beginning part of the data is cut off due to a data

acquisition error.

FIGURE 5: TEST 1.1: TEMPERATURES – SHORT CIRCUIT WITH 100 mΩ

Test Maximum

Temperature (°C)

1 111.9

2 30.3*

3 112.7




5.3 Conclusions

The maximum temperature observed out of each test was 112.7 °C. Final OCV values after

all testing are listed in Table 3, and show that the voltages decreased by an average of 1.27 V after

the test. All of the batteries resulted in a Hazard Severity Level of 2, as outlined in SAE J2464

regulation. No venting, rupture or fire occurred.


6.0 TEST GROUP 2 – SHORT CIRCUIT TESTING WITH 500 mΩ


The Solid Power 2 Ah battery cell was tested in accordance with the short circuit criteria

of SAE J2464. The testing precondition involved heating the battery cells for 3 hours at 45 °C,

and then battery cells are charged constant current 0.2 A until battery cell voltage reaches 4.2 V.

The battery cell was then placed into a blast chamber for safety. A short circuit with a 500 mΩ

resistance condition at ambient temperature as measured on the top surface of the DUT was then

applied and maintained for sixty minutes. Test ended if thermal runaway was detected. Figure 8

below shows the configuration of the test setup for this portion of testing.

FIGURE 8: TEST CONFIGURATION – SHORT CIRCUIT WITH 500 mΩ

6.2 Test Results

The Solid Power battery cells were subjected to the 4.5.1: Short Circuit Test in accordance




for each of the three test articles are listed in the table below. All three tests had a slight decrease

in voltage, losing 0.733 V, 0.715 V, and 0.692 V, respectively.

TABLE 5: BATTERY CELL OCV TEST RECORD – 500 mΩ GROUP

Sample Pre

OCV (V)

Post

OCV (V)

Reduction

(V)

1 4.120 3.387 0.733

2 4.120 3.405 0.715

3 4.090 3.398 0.692

Figures 6-8 below show temperature and voltage versus time for each test. Each test ran

for an hour (3600 seconds). Each figure shows a voltage trace that is expected for a short circuit

test. The voltage started at 4.2 V, but once the short circuit was applied the voltage first dropped

down to about 1.5 V and from there dropped down slowly to 0 V. At the end of the short circuit

test, the short circuit was removed causing the battery cell voltage to increase. The ending voltage

was reduced due to the short circuit test, with each test ending at almost 3.5 V.

The temperatures for each test began at ambient conditions, around 23 . Once the short

circuit was applied, the temperatures began to increase to a maximum level with the values shown

in Table 4 below. As the short circuit continued, more current ran through the system and the

charge of the battery cell dropped. Over time, this caused the temperature to decrease slowly. In

each test, Thermocouples 3 and 4 recorded higher temperatures than Thermocouples 1 and 2. Once

the test ended and the voltage restored, the temperatures ended between 30 and 35 and then

returned to ambient conditions.

TABLE 6: MAXIMUM TEMPERATURE – SHORT CIRCUIT WITH 500 mΩ

Test

Maximum

Temperature (°C)

1 43.2

2 43.9

3 43.1


6.3 Conclusions

The maximum temperature observed out of each test was 43.9 °C. Final OCV values after

all testing are listed in Table 5, and show that the voltages decreased by an average of 0.713 V

after the test. All of the batteries resulted in a Hazard Severity Level of 2, as outlined in SAE J2464

regulation. No venting, rupture or fire occurred.

solid power 2 ah solid-state battery cell abuse …

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