Final Report to NASAJSC Thermal Abuse Performance of MOLI ... · Panasonic and Sanyo 18650 Li-Ion...

SANDIA REPORT

SAND2004-6721 Unlimited Release Printed March 2005 Final Report to NASAJSC Thermal Abuse Performance of MOLI, Panasonic and Sanyo 18650 Li-Ion Cells

E. Peter Roth

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SAND2004-6721 Unlimited Release

Printed March 2005

Final Report to NASA JSC

Thermal Abuse Performance of MOLI, Panasonic and Sanyo 18650 Li-Ion Cells

E. Peter Roth Lithium Research and Development Department

Sandia National Laboratories P.O. Box 5800

Albuquerque, NM 87185-0613

Abstract

Thermal property measurements of 18650 cells for the Space Shuttle Orbiter Advanced Hydraulic Power System (AHPS, formerly known as EAPU) have been performed. Cells were measured from three commercial manufacturers: E-One MOLI (12 cells), Panasonic (5 cells) and Sanyo (5 cells). Thermal property measurements of the MOLI 18650 cells included measurements of specific heat, self discharge (microcalorimetry), overcharge response and thermal runaway by accelerating rate calorimetry (ARC). The Panasonic and Sanyo cells were measured only for thermal runaway response in the ARC at increasing states of charge (3.8V, 4.0V, 4.2V, 4.3V).

3

ACKNOWLEDGEMENTS

The author wished to thank David Johnson for his invaluable assistance in performing this work.

4

Table of Contents

ABSTRACT........................................................................................................................3

ACKNOWLEDGEMENTS ..............................................................................................4

TABLE OF CONTENTS ..................................................................................................5

FIGURES............................................................................................................................6

TABLES..............................................................................................................................8

ACRONYMS AND ABBREVIATIONS..........................................................................9

1.0 INTRODUCTION.................................................................................................10

2.0 E-ONE MOLI........................................................................................................10

2.1 Electrical Acceptance Tests ..............................................................................10

2.2 Heat Capacity Test............................................................................................13

2.3 Microcalorimetry ..............................................................................................15

2.4 Overcharge........................................................................................................21

2.4.1 Overcharge (C/5) .....................................................................................21

2.4.2 Overcharge (C/2) .....................................................................................26

2.5 Thermal Runaway (ARC) ................................................................................31

3.0 Panasonic Cells...........................................................................................................34

3.1 Electrical Acceptance Test................................................................................34

3.2 ARC Thermal Runaway....................................................................................36

4.0 Sanyo Cells..................................................................................................................38

4.1 Electrical Acceptance Test................................................................................38

4.2 ARC Thermal Runaway....................................................................................40

5.0 Cell Comparisons .......................................................................................................43

6.0 Distribution.................................................................................................................54

5

FIGURES

Figure 1. Typical load profile ........................................................................................12

Figure 2. Typical charge/discharge profile ....................................................................12

Figure 3. ARC temperature profile for heat capacity measurement ..............................14

Figure 4. Heat output at increasing temperature as a function of cell voltage...............16

Figure 5. Heat output for each cell voltage as a function of increasing temperature ....16

Figure 6. Activation energy plots for cells at increasing SOC ......................................17

Figure 7. Microcal heat output for cells with increasing voltage at 25°C .....................18

Figure 8. Heat output for cells with increasing voltage at 35°C....................................18

Figure 9. Heat output for cells with increasing voltage at 45°C....................................19

Figure 10. Heat output for cells with increasing voltage at 65°C...................................19

Figure 11. Heat output for cells with increasing voltage at 80°C...................................20

Figure 12. Functional fits to Prefactor “A” terms for self-discharge heat output...........21

Figure 13. Schematic and photo of overcharge test apparatus........................................23

Figure 14. Current and voltage profiles during C/5 overcharge .....................................24

Figure 15. Cell temperature profile during C/5 overcharge............................................24

Figure 16. Cell heat output and cell voltage during C/5 overcharge ..............................25

Figure 17. Heat output and cell voltage as a function of %SOC for C/5 charge ............25

Figure 178. Current and voltage profiles during C/2 overcharge ...................................27

Figure 19. Cell temperature profile during C/2 overcharge............................................27

Figure 18. Cell heat output and cell voltage during C/2 overcharge ..............................28

Figure 19. Heat output and cell voltage as a function of %SOC for C/2 charge ............28

Figure 20. Average cell temperatures of Moli cells during overcharge at C/5 and C/2

charge rates ....................................................................................................29

Figure 21. Heat output during overcharge of Moli cells at C/5 and C/2 charge rates ....29

Figure 22. Overcharge cell voltage profiles for Moli cells at C/5 and C/2 charge rates 30

Figure 23. ARC thermal runaway profile for Moli cells at increasing SOC ..................32

Figure 24. Onset of thermal runaway for Moli cells at increasing SOC.........................32

Figure 25. Gas generation during ARC runs of Moli cells up to thermal runaway

Temperatures.................................................................................................33

6

Figure 26. Gas generation during ARC runs of Moli cells during thermal runaway and

Cooling..........................................................................................................33

Figure 27. Typical load profile of Panasonic cell during 1.5C/30s load ........................35

Figure 28. ARC thermal runaway profile for Panasonic cells at increasing SOC..........36

Figure 29. Onset of thermal runaway for Panasonic cells at increasing SOC ................37

Figure 30. Gas generation during ARC runs of Panasonic cells up to thermal runaway

Temperatures................................................................................................37

Figure 31. Gas generation during ARC runs of Panasonic cells during thermal runaway

and cooling....................................................................................................38

Figure 32. Typical load profile of Sanyo cell during 1.5C/30s load..............................39

Figure 33. ARC thermal runaway profile for Sanyo cells at increasing SOC ...............41

Figure 34. Onset of thermal runaway for Panasonic cells at increasing SOC ...............41

Figure 35. Gas generation during ARC runs of Sanyo cells up to thermal runaway

Temperatures................................................................................................42

Figure 36. Gas generation during ARC runs of Sanyo cells during thermal runaway and

Cooling.........................................................................................................42

Figure 37. ARC comparison of all three commercial cells during thermal runaway at

3.8V..............................................................................................................44

Figure 38. Comparison of onset of ARC thermal runaway for all three commercial

cells at 3.8V .................................................................................................45


4.0V..............................................................................................................45


cells at 4.0V ..................................................................................................46


cells at 4.0V and the earlier Sony cells at 4.1V ...........................................46


4.2V..............................................................................................................47


4.2V...............................................................................................................47


cells at 4.2V .................................................................................................48

7


cells and the earlier Sony cells at 4.2V........................................................48


cells and the earlier Sony cells at 4.2V (expanded scale) ............................49


4.3V..............................................................................................................49


cells at 4.3V .................................................................................................50


cells and the earlier Sony cells at 4.3V........................................................50


cells and the earlier Sony cells at 4.3V (expanded scale) ............................51

TABLES

Table 1. Incoming inspection values for MOLI cells ...................................................11

Table 2. Impedance and discharge capacity values for MOLI cells .............................13

Table 3. Heat capacity values for three MOLI cells .....................................................14

Table 4. Heat output and activation energies at increasing SOC and temperature.......17

Table 5. Summary of power law functional values fitting the microcalorimeter heat

outputs as a function of time (x=time in hrs)..................................................20

Table 6. Incoming Inspection Values for Panasonic Cells ..........................................34

Table 7. Electrical Acceptance Tests for Panasonic Cells...........................................35

Table 8. Incoming Inspection Values for Sanyo Cells ................................................39

Table 9. Acceptance Tests for Sanyo Cells .................................................................40

Table 10. Comparison of Commercial 18650 Li-Ion Cells ...........................................52

8

ACRONYMS AND ABBREVIATIONS

AHPS Advanced Hydraulic Power System

ARC Accelerating Rate Calorimeter/Calorimetry

CID Current Interrupt Device

EAPU Electrical Auxiliary Power Unit

SOC State of Charge

9

1.0 INTRODUCTION

1.1 Statement of work

The objective of this program is to obtain thermal data to evaluate commercial 18650 Li-ion cells for possible use in the NASA Advanced Hydraulic Power System (AHPS) upgrade to the Space Shuttle Orbiter. Evaluation of these cells includes:

o Acceptance/Electrical Testing

o Heat Capacity (3 cells at 100%SOC)

o ARC Thermal Runaway (3.8V, 4.0V, 4.2V, 4.3V).

o Self Discharge by Microcalorimetry (3.8V, 4.0V, 4.2V) (25°C, 35°C, 50°C, 65°C, 80°C)

o Overcharge heat output (C/2, C/5)

Cells were measured from three commercial manufacturers: E-One MOLI (2.3 Ah), Panasonic (2.1 Ah) and Sanyo (2.1 Ah). A full thermal property characterization was performed on the E-one MOLI cells while the Panasonic and Sanyo cells were measured only for thermal runaway response.

2.0 E-One MOLI Cells

2.1 Electrical Acceptance Tests

Incoming inspection included measurement of open circuit voltage (OCV), weight and dimensions. Table I lists the measured values for the 12 cells received. A load check was performed with a 2.25 A current for 30 seconds to determine load voltage and impedance. The load checks for the Moli cells were performed at the as-received OCV of 3.8V. Figure 1 shows a typical load profile while Table 2 lists the measured load voltages and computed impedances. Two charge/discharge cycles were also performed at a 0.5 A charge rate to 4.2V and a 0.5 A discharge rate to 2.7V. A typical discharge curve is shown in Figure 2 while the discharge capacities are listed in Table 2. All cells were closely matched.

10

Table 1. Incoming inspection values for MOLI cells.

NASA Moli cells# Weight(g) Height (mm) Diameter(mm) OCV

NM01 47.61 65.0 18.1 3.802NM02 47.53 65.1 18.0 3.802NM03 47.64 65.0 18.1 3.802NM04 47.63 65.1 18.0 3.803NM05 47.60 65.1 18.1 3.803NM06 47.53 65.1 18.1 3.803NM07 47.63 65.1 18.1 3.803NM08 47.56 65.1 18.2 3.802NM09 47.55 65.0 18.1 3.803NM10 47.70 65.1 18.1 3.803NM11 47.57 65.0 18.2 3.802NM12 47.65 65.1 18.2 3.802Average 47.60 65.1 18.1 3.803StDev 0.053 0.049 0.067 0.001

11

Incoming Inspection of NASAMoli Cell NM01

2

2.5

3

3.5

4

4.5

0 2 4 6 8 10 12 14 16 18 20

Time (hr)

Vo

ltag

e (V

)

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Cu

rren

t (A

)

Voltage

Current

2.313 Ah 2.307 Ah

Figure 2. Typical charge/discharge profile.

Incoming Inspection of NASAMoli Cell NM01 CCV

3.5

4

4.5

0.5

1V1:

3.550 VV2:

3.450 VVo: 3.802 V

0

0.5

1

1.5

2

2.5

3

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Time (min)

Vo

ltag

e (V

)

-2.5

-2

-1.5

-1

-0.5

0

Voltage

Current

Figure 1. Typical load profile.

12

Table 2. Impedance and discharge capacity values for MOLI cells.

CellDischarge

Capacity1 (Ah)Discharge

Capacity2 (Ah) Vo V1 V2Ohmic Res.

(V0-V1)/IFinal Res. (Vo-

V2)/I Diff.

NM01a 2.313 2.307 3.802 3.550 3.450 0.112 0.156 0.044NM02a 2.306 2.301 3.802 3.550 3.450 0.112 0.156 0.044NM03a 2.310 2.305 3.802 3.545 3.445 0.114 0.159 0.044NM04a 2.315 2.308 3.802 3.523 3.422 0.124 0.169 0.045NM05a 2.316 2.308 3.802 3.541 3.439 0.116 0.161 0.045NM06a 2.310 2.303 3.802 3.551 3.448 0.112 0.157 0.046NM07a 2.306 2.298 3.802 3.484 3.401 0.141 0.178 0.037NM08a 2.307 2.301 3.802 3.541 3.429 0.116 0.166 0.050NM09a 2.308 2.302 3.802 3.547 3.447 0.113 0.158 0.044NM10a 2.319 2.311 3.802 3.545 3.443 0.114 0.160 0.045NM11a 2.311 2.304 3.802 3.550 3.449 0.112 0.157 0.045NM12a 2.311 2.304 3.802 3.543 3.441 0.115 0.160 0.045

Avg= 2.311 2.304 Avg= 0.117 0.161 0.045Std. Dev.= 0.004 0.004 Std. Dev.= 0.008 0.007 0.003

2.2 Heat Capacity Tests

Heat capacity was measured in the Accelerating Rate Calorimeter (ARC) using techniques that we have described previously. Generally, the ARC is in the adiabatic mode while heat is applied to the cell using a resistive wire wrapped around the cell. The slope of the temperature/time profile gives the heat capacity. Prior to cell measurements, heat capacities of known reference materials (Cu, Al) are measured using the same addenda materials. These calibration and addenda values were used for the actual cell heat capacity determinations. Figure 3 shows the ARC temperature profile for 4 heating rates of Moli cell #1. Average heat capacity values are calculated for each cell. It was found that the lower two temperature values gave the most consistent values for heat capacity. Table 3 lists the heat capacity values for the three cells measured. The average specific heat of the three cells is 0.823 J/g-C (1.9 % Std. Dev.) that is slightly lower than the 0.902 J/g-C measured previously for the Sony cells. The major difference results from the 13% higher mass of the Moli cells.

13

Heat Capacity Run: MOLI Cell #1

y = 6.2384x + 14.65

y = 10.728x - 8.5213

y = 16.686x - 49.384

y = 23.929x - 111.8

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 2 4 6 8 10

Vo

lts

/Am

ps

20

30

40

50

60

70

80

90

100

Te

mp

(C

)

.382 W

.267 W

.167 W

.095 W

time (hrs)Figure 3. ARC temperature profile for heat capacity measurement.

Table 3. Heat capacity values for three MOLI cells.

Cell # Average Heat Capacity (J/C)

Specific Heat (J/g-C)

1 38.0 0.806

2 38.8 0.826

3 39.5 0.837

Avg. 38.8 0.823

Std.Dev. 0.72 0.016

% Std. Dev. 1.9% 1.9%

14

2.3 Microcalorimetry:

Microcalorimetry was performed on the Moli cells at three cell voltages (3.8V, 4.0V, 4.2V). Measurements were performed at 25°C, 35°C, 45°C, 65°C and 80°C for periods of at least 25 hours. Some cells were measured for longer time periods if the initial measurements overlapped with the weekend. Figure 4 shows the heat outputs at each temperature as a function of increasing cell voltage while Figure 5 shows the heat output at each voltage as a function of increasing temperature. All heat output values were taken over the time period 24-25hrs after the cell was placed in the microcalorimeter as a common reference temperature range. This delay time was necessary to allow the microcalorimeter to fully equilibrate after the temperature disturbance from the inserted cell. These values were used to calculate the activation energy for each cell voltage as shown in Figure 6. Table 4 lists the measured values. The activation energies decreased with increasing cell voltage from 15.6 kcal/mole to 12.2 kcal/mole. The average activation energy was 13.9 kcal/mole (58.0 kJ/mole).

The heat outputs from the cells decreased as a function of time and were seen to obey a power law function as seen previously for the Sony cells. The only cells that did not clearly fit this form were the cells measured at 25°C. The response for these cells was different because there was no clear start time for the self-discharge reaction. The cells were already near this temperature during the cycling and handling prior to insertion into the microcal. Figures 7-11 show the microcalorimeter heat output for each cell voltage as a function of temperature. The functional form of the heat output can be expressed as:

Heat Out (uW) = A x (time(hrs))^B

The “A” term is the prefactor indicating the magnitude of the heat output one hour after being placed in the microcal at the measurement temperature. The “B” term is the power exponent of the time decay. Table 5 lists the values for the fits to each cell at increasing voltage and temperature. The prefactor term increases with increasing voltage and temperature while the power term can be expressed as an average of B= -0.22. Figure 12 shows that the prefactor “A” terms themselves can be fit with a power law curve and can be used to interpolate this prefactor which, along with the average power exponent, can be used to calculate the heat output over this entire temperature range for the three cell voltages measured. The self-discharge reaction is primarily an irreversible reaction that results in greater cell stability with time. These heat outputs represent the initial cell response when first exposed to these voltage and temperature conditions. Subsequent cell response when re-exposed after initial self-discharge reactions will be less than indicated here.

15

0

1000

2000

3000

4000

5000

6000

7000

3.7 3.8 3.9 4 4.1 4.2 4.3

Cell Voltage

Hea

t O

ut

(uW

)

25C

35C

45C

65C

80C

Figure 4. Heat output at increasing temperature as a function of cell voltage.

0

1000

2000

3000

4000

5000

6000

7000

20 30 40 50 60 70 80 90

Temperature (C)

Hea

t O

ut

(uW

)

3.8V

4.0V

4.2V

Figure 5. Heat output for each cell voltage as a function of increasing temperature.

16

Voltage Temp (C ) Heat Out (uW) slope E(Kcal/mole)

3.8V 25 50.1 7862.2 15.623.8V 35 101.73.8V 45 223.33.8V 65 1149.33.8V 80 2756.3

4.0V 25 80.2 6925.7 13.764.0V 35 228.44.0V 45 445.34.0V 65 14774.0V 80 3290.7

4.2V 25 238.5 6152.8 12.234.2V 35 5094.2V 45 1001.54.2V 65 28894.2V 80 6163.7

Avg= 13.87std dev= 1.70%s.d.= 12.3%

Table 4. Heat output and activation energies at increasing SOC and temperature.

Arrhenius Plot of Microcal Output for MOLI Cells Avg. activation energy (3.8V-4.2V)= 13.9 kcal/mole

3.8V: 15.6 kcal/mole y = -7.8622x + 30.216

R2 = 0.9976

4.0V: 13.8 kcal/mole y = -6.9257x + 27.785

R2 = 0.9935

4.2V: 12.2 kcal/moley = -6.1528x + 26.183

R2 = 0.9984

0

1

2

3

4

5

6

7

8

9

10

2.8 2.9 3 3.1 3.2 3.3 3.4

1000/T(K)

ln(H

eat

Ou

t (u

W))

4.2V

4.0V

3.8V

Figure 6. Activation energy plots for cells at increasing SOC.

17

MOLI Cells: 25C

4.0V

y = 83.236x-0.035

R2 = 0.7422

4.2V

y = 333.32x-0.1009

R2 = 0.9645

3.8V

y = 93.929x-0.2227

R2 = 0.99

0

100

200

300

400

500

0 5 10 15 20 25 30 35 40 45 50

time (hrs)

He

at

(uW

)

4.2V

4.0V

3.8V

Figure 7. Microcal heat output for cells with increasing voltage at 25°C.

MOLI Cells 35C

3.8V

y = 212.92x-0.2149

R2 = 0.9983

4.0V

y = 444.74x-0.2125

R2 = 0.9957

4.2V

y = 893.78x-0.1815

R2 = 0.9977

-100

0

100

200

300

400

500

600

700

800

900

1000

0 10 20 30 40 50 60

time (hrs)

He

at

(uW

)

4.2V

4.0V

3.8V

Figure 8. Heat output for cells with increasing voltage at 35°C.

18

MOLI Cells 45C

3.8V

y = 511.09x-0.2444

R2 = 0.9913

4.0V

y = 733.45x-0.1525

R2 = 0.9994

4.2V

y = 2097.8x-0.2338

R2 = 0.9947

0

200

400

600

800

1000

1200

1400

1600

1800

0 10 20 30 40 50 60 70 80 90 100

time (hrs)

He

at

(uW

)


MOLI Cells 65C

4.0V

y = 2979.2x-0.2127

R2 = 0.9962

4.2V

y = 6514.5x-0.2564

R2 = 0.9751

3.8V

y = 2681.6x-0.2678

R2 = 0.9944

-200

300

800

1300

1800

2300

2800

3300

3800

4300

4800

0 10 20 30 40 50 60 70

time (hrs)

He

at

(uW

)

4.2V

4.0V3.8V


19

MOLI Cells 80C

4.0V

y = 8117.8x-0.2752

R2 = 0.9848

3.8V

y = 10330x-0.406

R2 = 0.9921

4.2V

y = 15644x-0.2752

R2 = 0.9518

0

2000

4000

6000

8000

10000

12000

0 5 10 15 20 25 30 35

time (hrs)

He

at

(uW

)

4.2V

4.0V

3.8V


Table 5. Summary of power law functional values fitting the microcalorimeter heat outputs as a function of time (x=time in hrs).

Cell Temp(C ) Voltage prefactor "A" power "B" Function5 25 3.8 93.9 -0.222 y = 93.867x-0.22245 25 4 82.6 -0.028 y = 82.591x-0.02835 25 4.2 336.8 -0.11 y = 336.81x-0.10966 35 3.8 212.9 -0.215 y = 212.92x-0.21496 35 4 444.7 -0.212 y = 444.74x-0.21256 35 4.2 893.8 -0.182 y = 893.78x-0.18157 45 3.8 511.1 -0.244 y = 511.09x-0.24447 45 4 733.5 -0.152 y = 733.45x-0.15257 45 4.2 2098 -0.234 y = 2097.8x-0.23388 65 3.8 2682 -0.268 y = 2681.6x-0.26788 65 4 2979 -0.213 y = 2979.2x-0.21278 65 4.2 6514 -0.256 y = 6514.5x-0.25649 80 3.8 10330 -0.406 y = 10330x-0.4069 80 4 8117 -0.275 y = 8117.8x-0.27529 80 4.2 15644 -0.275 y = 15644x-0.2752

avg std dev %std dev>25C <80C -0.220 0.036 16.6%

20

4.2V

y = 1.43E-02x3.12E+00

R2 = 9.99E-01

3.8V

y = 1.59E-04x4.02E+00

R2 = 9.71E-01

4.0V

y = 5.09E-04x3.76E+00

R2 = 9.88E-01

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

0 10 20 30 40 50 60 70 80 90

Temperature (C)

Pre

fact

or

3.8V

4.0V

4.2V

Figure 12. Functional fits to Prefactor “A” terms for self-discharge heat output.

2.4 Overcharge

2.4.1 Overcharge at (C/5)

Quantitative measurements of the heat flow from the cell during overcharge were initially performed at a C/5 (480mA) charge rate starting at 100%SOC (4.2V). A schematic of the test apparatus is shown in Figure 13. The cell was placed in a brass inner cylinder that allows good thermal contact to the cell and smoothes out any temperature variations, allowing a radially symmetric flow of heat. This inner cylinder was thermocoupled and wrapped with layers on insulating glass tape that serves as a fixed thermal resistance. This fixture was then placed in an outer brass cylinder that was thermocoupled to allow measurement of the delta T across the tape in three locations. This system was calibrated with a heated insert with the same dimensions as an 18650 cell. The insert was then removed without disturbing the calibrated heat path through the glass tape. Cells were then inserted and overcharged at the selected rate. The delta T across the tape was used with the calibration function to calculate the heat generated by the cells. The fixture was placed in a Lexan container that was sealed to allow flow through of N2 gas for real time gas analysis by FTIR, MS and GC.

21

The current and voltage profiles are shown in Figure 14 while the temperature profile is shown in Figure 15. The cell charged continuously for almost 250 minutes until the current interrupt device (CID) activated and the current dropped to zero. The power supply voltage was limited to 12V at this time. After observing that the cell was cooling and did not appear to be likely to go into a thermal runaway, the power supply voltage was increased to 60V to simulate the higher voltages that might be experienced in a module. The current increased initially due to the increased power surge but then also started to drop. The test was then terminated. Two voltage peaks were observed during the overcharge at 4.95V and 5.05V. At both of these peaks the cell temperature and heat output showed an increase in the rate of rise. These peaks occurred at low cell temperatures of only 25°C and 37°C. Figure 16 shows the cell voltage and the corresponding heat output. The heat output averaged around 22mW prior to these increases. The heat output was increasing rapidly up to the point of the CID activation and reached a value of 1.25 watts. The subsequent increase in applied voltage spiked the heat output to 1.6 watts. Figure 17 shows the heat output and cell voltage plotted as a function of %SOC. The two voltage peaks occurred at 160%SOC and 177%SOC followed by CID activation at 185%SOC. We have seen single voltage peaks at 5.13V in our test cells built with similar chemistry. These lower peaks may result from overcharge additives used by this manufacturer.

During the overcharge run we measured gas evolution from the cell beginning around 146%SOC and at a cell temperature of 23.6°C. We monitored steadily increasing gas generation during the run but at no time did we see evidence of a cell vent. The internal gases generated during overcharge were able to leak around the crimp seals of the cell. Eventually the gas generation rate increased the internal pressure sufficiently to activate the CID even though some gas was being lost. Without this low-rate leak, the CID would have probably have activated sooner. Gas analysis showed that the gases consisted primarily of CO2, methane and solvent vapors.

22

Cell current/voltage leads

Cell TC leads

CellUpper Thermocouples – Cell surface and

Outside Insulation

Lower Thermocouples

Mid –Thermo-couples

Insulation(calibrated

thermal resistance)

Outer Insulation

Radial Heat Flow

Cell current/voltage leads

Cell TC leads

CellUpper Thermocouples – Cell surface and

Outside Insulation

Lower Thermocouples

Mid –Thermo-couples

Insulation(calibrated

thermal resistance)

Outer Insulation

Radial Heat Flow

Figure 13. Schematic and photo of overcharge test apparatus.

23

MOLI Cell#10.48amp charge starting at 100%SOC

4

4.2

4.4

4.6

4.8

5

5.2

5.4

5.6

5.8

6

0 50 100 150 200 250 300

Offset Time/min

Ce

ll V

olt

ag

e/V

olt

s

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Cu

rre

nt

(am

ps

)

Voltage

Current

CID Activated

Figure 14. Current and voltage profiles during C/5 overcharge.


20

25

30

35

40

45

50

55

60

0 50 100 150 200 250 300

Offset time (min)

Te

mp

(C

)

Figure 15. Cell temperature profile during C/5 overcharge.

24

25


0

500

1000

1500

2000

2500

3000

3500

4000

0 50 100 150 200 250 300

offset time (min)

Po

wer

(m

W)

4

4.2

4.4

4.6

4.8

5

5.2

5.4

5.6

5.8

6

Cel

l vo

ltag

e

Heat Out (mW) [Calc. HTC]

Voltage

Figure 16. Cell heat output and cell voltage during C/5 overcharge.


0200400600800

100012001400160018002000

100% 120% 140% 160% 180% 200%

% SOC

Hea

t O

ut

(mW

)

4

4.2

4.4

4.6

4.8

5

5.2

5.4

5.6

5.8

6

Cel

l Vo

lta

ge

22mW avg.

160%SOC

177%SOC

CID activated

First Gas

Figure 17. Heat output and cell voltage as a function of %SOC for C/5 charge.

2.4.2 Overcharge at (C/2):

A second overcharge run was performed at a C/2 rate (1.2 A). The current and voltage profiles are shown in Figure 18. The overcharge was started with the cell at 100%SOC and continued until the current interrupt device activated. The voltage profile showed the same two voltage peaks as seen for the C/5 charge. The cell temperature shown in Figure 19 indicates that the cell reached 68°C before the CID activated and then started to cool. No thermal runaway behavior was observed. The corresponding heat output and cell voltage profiles are shown in Figure 20. The first cell voltage peak corresponds to a rapid rise in generated heat. At the second peak, the rate of heat output increased again and peaked at 2600 mW at CID activation. The temperature and heat output were increasing at an accelerating rate at shutdown and could have resulted in a thermal runaway without the CID. The heat output and cell voltage are shown as a function of state of charge in Figure 21. The first voltage occurred at 160%SOC followed by the second peak at 180%SOC. No gas generation was observed during this run.

The average cell temperatures and heat output for the C/5 and C/2 runs are compared in Figures 22 and 23 as a function of SOC. The cell temperature and heat output increased sharply for both charge rates at 160%SOC (first voltage peak) and also at 180%SOC (second voltage peak). The magnitude of the generated heat was greater at the higher charge rate as expected due to increase ohmic and polarization heating. The cell voltage profiles are compared in Figure 24. The two charge rates both resulted in very similar cell voltage responses at a given state of charge. Both cells experienced CID activation at 185%SOC. Since CID activation was limiting the ability to overcharge the cell the third overcharge cell run was not performed.

26


3

3.5

4

4.5

5

5.5

6

0 20 40 60 80 100 120

Offset Time/min

Cel

l V

olt

age/V

olt

s

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Cu

rren

t (a

mp

s)

Cell voltage

Current

CID Activated

Figure 18. Current and voltage profiles during C/2 overcharge.


20

30

40

50

60

70

80

0 20 40 60 80 100 120

Offset time (min)

Te

mp

(C

)

Figure 19. Cell temperature profile during C/2 overcharge.

27


0

500

1000

1500

2000

2500

3000

3500

4000

0 20 40 60 80 100 120

offset time (min)

Po

wer

(m

W)

4

4.2

4.4

4.6

4.8

5

5.2

5.4

5.6

5.8

6

Ce

ll v

olt

ag

e

Heat Out (mW) [Calc. HTC]

Cell voltage

Figure 20. Cell heat output and cell voltage during C/2 overcharge.


0

500

1000

1500

2000

2500

3000

100% 120% 140% 160% 180% 200%

% SOC

Hea

t O

ut

(mW

)

4

4.2

4.4

4.6

4.8

5

5.2

5.4

5.6

5.8

6

Cel

l V

oltag

e

160%SOC

180%SOC

CID activated

Figure 21. Heat output and cell voltage as a function of %SOC for C/2 charge.

28

20

30

40

50

60

70

80

100% 120% 140% 160% 180% 200%

%SOC

Av

g C

ell

Te

mp

MOLI Cell#1: 0.478 amps (N2)


Figure 22. Average cell temperatures of Moli cells during overcharge at C/5 and C/2 charge rates.

0

500

1000

1500

2000

2500

3000

100% 120% 140% 160% 180% 200%%SOC

Hea

t O

ut

mW



Figure 23. Heat output during overcharge of Moli cells at C/5 and C/2 charge rates.

29


4

4.2

4.4

4.6

4.8

5

5.2

5.4

5.6

5.8

6

100% 120% 140% 160% 180% 200%

%SOC

Vo

ltag

e/V

olt

s



Figure 24. Overcharge cell voltage profiles for Moli cells at C/5 and C/2 charge rates.

30

2.5 Thermal Runaway (ARC)

Thermal runaway response of the cells was measured in the accelerating rate calorimeter (ARC) under adiabatic conditions up to 450°C at increasing states of charge (3.8V, 4.0V, 4.2V, 4.3V). Thermal runaway is defined as the self-generated heating of the cell which exceeds a threshold rate limit of 0.02°C /min under the ARC adiabatic conditions. A new fixture was designed and constructed to allow full thermal runaway of the 18650 cells in a sealed container which minimized the expansion volume for the evolved gases. This low volume reduced cooling of the cells during the high gas release thermal runaway but also significantly increased the pressure in the cell fixture. These controlled conditions allow a better side-by-side comparison of the different commercial cells. However, a thermal runaway/vent reaction into an unconstrained volume would have somewhat reduced heating rates. The gas pressure during the run was measured and used to calculate the STP equivalent volume of generated gas. Most of the runs maintained a pressure seal up to 2000psi at 500°C but some of the runs experienced a pressure leak during the explosive runaway. The pressure data after a leak event was not used to calculate evolved gas volumes and is indicated by a truncated display in the figures.

Figure 25 shows the heating rate data for the four MOLI cells at increasing voltages. Heating rates were measured as high as 1200°C/min. At heating rates higher than about 10°C /min the cell temperature exceeds the ability of the ARC to maintain adiabatic conditions and the cell temperature will temporarily exceed the ARC temperature. After the thermal runaway peak the cell temperature will cool back down to the ARC temperature and the controlled run will continue. Usually, the maximum ARC temperature has been reached and the ARC begins active cooling. The high cell heating rates began in the range 180°C - 200°C, increasing with increasing cell voltage. Peak heating rates occurred in the range of 250°C - 300°C. The onset of thermal runaway is more clearly shown in Figure 26. Onset occurred around 160°C for the 3.8V cell and decreased with increasing cell voltage down to 130°C for the 4.3V cell.

Measured gas evolution was detected after cell venting which typically occurred in the 130°C - 150°C range (Figure 27). The temperature of cell venting decreased with increasing cell voltage indicating that higher states of charge result in increased gas generation in the cell leading to higher internal pressures. The 3.8V cell did not show a discrete vent but showed increased gas generation starting at 120°C, suggesting that it may have had a leaky seal. After venting, all of the cells showed similar gas evolution rates with increasing temperature up to the thermal runaway temperature with a total evolved gas level of 300ml – 350ml just prior to runaway. During thermal runaway the evolved gases did not increase at the same rapid rate as the temperature. However, the gas volume increased steadily over time even while the cell was cooling (Figure 28). The total gas volume evolved for these Moli cells in this “smoking rubble” state was about 1700 ml (+/- 200 ml). There was some larger volume of gas associated with the higher cell voltages.

31

MOLI Cells

0

200

400

600

800

1000

1200

1400

0 50 100 150 200 250 300 350 400 450 500

Temperature (C)

Rat

e (C

/min

)

Cell #10: 3.8V

Cell #11: 4.0V

Cell #12: 4.2V

Cell #4: 4.3V

3.8V

4.0V

4.2V

4.3V

Figure 25. ARC thermal runaway profile for Moli cells at increasing SOC.

MOLI Cells

0

1

2

3

4

5

6

7

8

9

10

100 120 140 160 180 200

Temperature (C)

Rat

e (

C/m

in)

Cell #10: 3.8V

Cell #11: 4.0V

Cell #12: 4.2V

Cell #4: 4.3V

3.8V4.0V4.2V4.3V

Figure 26. Onset of thermal runaway for Moli cells at increasing SOC.

32

MOLI Cells

0

100

200

300

400

500

600

700

800

100 120 140 160 180 200 220 240

Temperature (C)

ST

P v

ol

(ml)

Cell #10: 3.8V

Cell #11: 4.0V

Cell #12: 4.2V

Cell #4: 4.3V

Figure 27. Gas generation during ARC runs of Moli cells up to thermal runaway temperatures.

MOLI Cells

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 100 200 300 400 500 600

Temperature (C)

ST

P v

ol

(ml)

Cell #10: 3.8V

Cell #11: 4.0V

Cell #12: 4.2V

Cell #4: 4.3V

Figure 28. Gas generation during ARC runs of Moli cells during thermal runaway and cooling.

33

3.0 Panasonic Cells

3.1 Electrical Acceptance Test

Five Panasonic cell were received for evaluation of thermal runaway performance only. The initial acceptance data is shown in Table 6. All cells appeared normal. Electrical acceptance tests were performed as described for the Moli cells except that the pulse loading tests were performed at 100%SOC potential of 4.2V. Two charge/discharge cycles were performed at a C/3 rate giving an average cell capacity of 2.14 Ah. A 1.5C, 30s load pulse was then applied to each cell starting at the 100%SOC voltage of 4.2V. Table 7 lists the results for each of the five cells. An ohmic impedance of 103 mohms was measured with an average final cell resistance of 127 mohms (compared to 161 mohms for the Moli cells). A typical load pulse profile is shown in Figure 29.

Table 6. Incoming Inspection Values for Panasonic Cells

# Weight(g) Height (mm) Diameter (mm) OCVNP228 42.94 64.9 18.1 3.363NP229 43.23 64.8 18.1 3.367NP230 43.17 65.1 18.1 3.365NP231 43.35 64.8 18.2 3.366NP232 43.03 64.8 18.2 3.356Average 43.15 64.88 18.13 3.363StdDev 0.16 0.13 0.07 0.004

NASA Panasonic cells

34

Incoming CCV of NASAPanasonic Cell NP228

3.5

3.6

3.7

3.8

3.9

4

4.1

4.2

0 50 100 150 200

Time (sec)

Vo

ltag

e (V

)

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

Cu

rre

nt

(am

ps

)

Voltage

Current

Figure 29. Typical load profile of Panasonic cell during 1.5C/30s load.

Table 7. Electrical Acceptance Tests for Panasonic Cells

Cell

Discharge Capacity1

(Ah)

Discharge Capacity2

(Ah) Vo V1 V2Ohmic Res.

(V0-V1)/IFinal Res. (Vo-V2)/I Diff.

NP228 2.139 2.135 4.193 3.884 3.801 0.096 0.122 0.026NP229 2.143 2.14 4.193 3.879 3.806 0.098 0.121 0.023NP230 2.139 2.136 4.192 3.816 3.739 0.117 0.141 0.024NP231 2.147 2.143 4.193 3.866 3.784 0.102 0.127 0.026NP232 2.148 2.144 4.194 3.868 3.803 0.102 0.122 0.020

Avg= 2.143 2.140 Avg= 0.103 0.127 0.024

Std. Dev.= 0.004 0.004 Std. Dev.= 0.008 0.009 0.002

35

3.2 ARC Thermal Runaway

The Panasonic cells were also measured in the ARC from 3.8V to 4.3V. High rate thermal runaway was again observed in the 180°C to 200°C range as seen for the Moli cells. Peak heating rates were also seen up 1200°C/min as shown in Figure 30. Expansion of the onset temperature regime shows similar responses as seen for the Moli cells (Figure 31). Thermal runaway onset temperature decreased and heating rates increased with increasing cell voltage. All of the cells showed discrete vents with venting temperatures decreasing from 145°C to 120°C with increasing cell voltage (Figure 32). Gas evolution rates were similar after venting up to thermal runaway and each cell resulted in about 250ml – 300 ml of gas prior to runaway. Total evolved gas after runaway and subsequent cooling increased with increasing voltage up to a maximum of 2400 ml for the 4.2V cell (Figure 33). The 4.3V developed a leak at the thermal runaway event and gas volume was not recorded.

Panasonic Cells

0

200

400

600

800

1000

1200

1400

0 100 200 300 400 500

Temperature (C)

Ra

te (

C/m

in)

Panasonic Cell #230: 4.3V




3.8V

4.0V

4.2V

4.3V

Figure 30. ARC thermal runaway profile for Panasonic cells at increasing SOC.

36

Panasonic Cells

0

1

2

3

4

5

6

7

8

9

10

100 120 140 160 180 200

Temperature (C)

Rat

e (C

/min

)Panasonic Cell #230: 4.3V




3.8V4.0V4.2V4.3V

Figure 31. Onset of thermal runaway for Panasonic cells at increasing SOC.

Panasonic Cells

0

50

100

150

200

250

300

350

400

450

500

100 120 140 160 180 200 220 240

Temperature (C)

ST

P v

ol

(ml)




Panasonic Cell #232: 3.8V 3.8V

4.0V

4.2V

Figure 32. Gas generation during ARC runs of Panasonic cells up to thermal runaway temperatures.

37

Panasonic Cells

0

500

1000

1500

2000

2500

0 100 200 300 400 500 600

Temperature (C)

ST

P v

ol

(ml)





3.8V

4.0V

4.2V

Figure 33. Gas generation during ARC runs of Panasonic cells during thermal runaway and cooling.

4.0 Sanyo Cells

4.1 Electrical Acceptance Test

Five Sanyo cell were received for evaluation of thermal runaway performance only. The initial acceptance data is shown in Table 8. All cells appeared normal. Electrical acceptance tests were performed as described for the other cells. Two charge/discharge cycles were performed and a 1.5C, 30s load pulse was applied to each cell with the cells at 4.2V. Table 9 lists the results for each of the five cells. The average cell capacity was 2.14 Ah (same as for the Panasonic cells) and the average final cell resistance was 152 mohms (126 mohms ohmic), slightly higher than for the Panasonic cells (127 mohms total/103 mohms ohmic). The pulse load tests were performed at 4.2V as was done for the Panasonic cells. A typical load pulse profile is shown in Figure 34. Two of the cells showed an irregular voltage profile for a few seconds after pulse loading but the profiles stabilized after a few seconds. The other cells showed profiles similar to the other two commercial cells.

38

Table 8. Incoming Inspection Values for Sanyo Cells

# Weight(g) Height (mm)Diameter(mm) OCV

NS772 45.30 64.8 18.1 3.788NS788 45.27 65.1 18.2 3.788NS809 45.12 64.8 18.1 3.788NS829 45.63 64.8 18.1 3.788NS830 45.33 64.9 18.2 3.788Average 45.33 64.89 18.15 3.788

StdDev 0.19 0.13 0.02 0.000

NASA Sanyo cells

Incoming CCV of NASASanyo Cell NS788

3.5

3.6

3.7

3.8

3.9

4

4.1

4.2

0 50 100 150 200

Time (sec)

Vo

ltag

e (V

)

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

Cu

rre

nt

(am

ps

)

Voltage

Current

Figure 34. Typical load profile of Sanyo cell during 1.5C/30s load.

39

Table 9. Acceptance Tests for Sanyo Cells

Cell

Discharge Capacity1

(Ah)

Discharge Capacity2

(Ah) Vo V1 V2Ohmic Res.

(V0-V1)/IFinal Res. (Vo-V2)/I Diff.

NS772 2.138 2.134 4.191 3.712 3.644 0.149 0.170 0.021NS788 2.141 2.142 4.187 3.738 3.696 0.139 0.152 0.013NS809 2.127 2.125 4.192 3.805 3.744 0.120 0.139 0.019NS829 2.152 2.152 4.192 3.859 3.779 0.103 0.128 0.025NS830 2.147 2.146 4.192 3.801 3.642 0.121 0.171 0.049

Avg= 2.141 2.140 Avg= 0.126 0.152 0.025Std. Dev.= 0.010 0.011 Std. Dev.= 0.018 0.019 0.014

4.2 ARC Thermal Runaway

The Sanyo cells were also measured in the ARC from 3.8V to 4.3V. High rate thermal runaway was again observed in the 180°C to 200°C range as seen for the Moli and Panasonic cells. Peak heating rates were seen up 900°C/min as shown in Figure 35, lower than seen for the other cells. Expansion of the onset temperature regime shows similar responses as seen for the Moli and Panasonic cells but with two additional reaction events seen for the 4.0V and 4.3V cells (Figure 36). These reactions could result from interactions with electrolyte additives for this particular cell chemistry. Thermal runaway onset temperature decreased and heating rates increased with increasing cell voltage as seen for the other cells. All of the cells showed discrete vents over a narrow range (125°C to 130°C ) with venting temperatures slightly decreasing with increasing cell voltage (Figure 37). Gas evolution rates were similar after venting up to thermal runaway and each cell resulted in about 350 ml of gas prior to runaway (the 3.8V and 4.3V cells developed leaks). Total evolved gas after runaway and subsequent cooling increased with increasing voltage up to a maximum of 2400 ml for the 4.2V cell (Figure 38).

40

Sanyo Cells

0

100

200

300

400

500

600

700

800

900

1000

0 100 200 300 400 500

Temperature (C)

Rat

e (

C/m

in)

SanyoCell #809: 4.3V

SanyoCell: 4.2V



3.8V

4.0V

4.2V

4.3V

Figure 35. ARC thermal runaway profile for Sanyo cells at increasing SOC.

Sanyo Cells

0

1

2

3

4

5

6

7

8

9

10

100 120 140 160 180 200

Temperature (C)

Rate

(C

/min

)


SanyoCell: 4.2V



3.8V4.0V4.2V4.3V

Figure 36. Onset of thermal runaway for Panasonic cells at increasing SOC.

41

Sanyo Cells

0

50

100

150

200

250

300

350

400

450

500

100 150 200 250

Temperature (C)

ST

P (

ml)


SanyoCell: 4.2V



3.8V4.0V

4.2V

4.3V

Figure 37. Gas generation during ARC runs of Sanyo cells up to thermal runaway temperatures.

Sanyo Cells

0

500

1000

1500

2000

2500

0 100 200 300 400 500 600

Temperature (C)

ST

P (

ml)

SanyoCell #809: 4.3VSanyoCell: 4.2VSanyoCell #778: 4.0VSanyoCell #772: 3.8V

3.8V

4.0V

4.2V

4.3V

Figure 38. Gas generation during ARC runs of Sanyo cells during thermal runaway and cooling.

42

5.0 Cell Comparisons

These measurements of the Moli, Panasonic and Sanyo cells described in this report were preceded by an earlier series of measurements of commercial Sony cells (1.4 A/h). The ARC thermal runaway response for these cells was measured at cell voltages of 4.1V, 4.2V, 4.3V, 4.4V and 4.5V. These cells were measured using an early cell fixture which did not allow pressure controlled measurements above the peak thermal runaway temperature and the relative ARC data only shows runaway up to the 150°C -200°C range. Comparisons of the current cells with the Sony cells are made at the same (or similar) cell voltages. The ARC thermal runaway profiles at each cell voltage are compared in Figures 39 – 52. Comparisons are also made with the Sony cells measured in an earlier study for some of the cell voltages.

• 3.8V (Figures 39 and 40): The thermal runaway onsets are very similar (150°C) but the Sanyo cell showed slightly lower heating rate. The Panasonic cell showed somewhat higher peak heating rate of 650°C/min at 275°C.

• 4.0V (Figures 41 and 42): The Sanyo cell showed a definite lower peak heating rate (700°C/min) than for either the Panasonic or Moli cells. The onset temperature profiles all looked the same with an onset temperature around 140°C. The peak heating rates increased up to 1000 °C/min and continued up to 300°C. Figures 43 and 44 show the same data compared with the Sony data. The Sony cells showed higher heat output at low temperatures with an untypical exothermic reaction between 135°C - 175°C and then showing lower reaction rate at higher temperatures. The Sony cells were not measured under controlled conditions through the runaway peak and the data are not shown.

• 4.2V (Figure 45 and 46): The Sanyo cell showed much lower peak heating rate (800°C/min) compared to the Moli and Panasonic cells which were both very similar at 1200°C/min. The onset temperature profiles were very similar starting at 130°C. Peak heating rates remained around 300°C. The Sony cell comparisons are shown in Figures 47 and 48. The Sony cell again showed increased heat out at the low temperatures. A distinctive breakdown of the anode protective layer is seen at 110°C followed by an exothermic reaction between 135°C and 165°C. At higher temperatures the heating rates were similar to the other cells.

• 4.3V (Figure 49 and 50): The Sanyo cell still shows a lower peak heating rate (900°C/min) but is much closer to the Moli and Panasonic cells (1100°C/min). The onset temperatures are still similar with onset around 120°C. The Sanyo cell showed the narrow reaction peak around 150°C. Peak heating rates remained

43

around 300°C. The Sony cell comparison is shown in Figures 51 and 52. The breakdown of the anode layer was again seen at 110°C but no reaction peak was seen at 135°C. At 4.2V, the Sony cells and the three commercial cells studied here behaved very similarly.

Overall, the Sanyo cells show slightly better thermal runaway performance but have lower capacity than the Moli cells. The Sanyo cells show some evidence of additives or electrode stabilization but these do not have any significant detrimental effect on cell thermal performance. The Moli cells had similar thermal response to the Panasonic cells but with increased capacity. For the same capacity level, the Sanyo cells showed superior thermal performance over the Panasonic cells. Table 10 shows a comparison of the thermal and electrical data obtained for each of the three current commercial cells and the previous Sony cells.

3.8V Cells

0

200

400

600

800

1000

1200

1400

0 100 200 300 400 500

Temperature (C)

Rat

e (C

/min

)



MOLI Cell #10: 3.8V

Sanyo

Panasonic

MOLI

Figure 39. ARC comparison of all three commercial cells during thermal runaway at 3.8V.

44

3.8V Cells

0

1

2

3

4

5

6

7

8

9

10

100 120 140 160 180 200

Temperature (C)

Rat

e (C

/min

)



MOLI Cell #10: 3.8V

Sanyo

Panasonic

MOLI

Figure 40. Comparison of onset of ARC thermal runaway for all three commercial cells at 3.8V.

4.0V Cells

0

200

400

600

800

1000

1200

1400

0 100 200 300 400 500

Temperature (C)

Rat

e (C

/min

)


MOLI Cell #11: 4.0V


Sanyo

MOLI

Panasonic


45

4.0V Cells

0

1

2

3

4

5

6

7

8

9

10

100 120 140 160 180 200

Temperature (C)

Rat

e (C

/min

)


MOLI Cell #11: 4.0V


Sanyo

MOLI

Panasonic


4.0V Cells

0

1

2

3

4

5

6

7

8

9

10

50 100 150 200

Temperature (C)

Rat

e (C

/min

)


MOLI Cell #11: 4.0V


Sony Cell: 4.1V

Sanyo

MOLI

Panasonic

Sony(4.1V)

Figure 43. Comparison of onset of ARC thermal runaway for all three commercial cells at 4.0V and the earlier Sony cells at 4.1V.

46

4.0V Cells

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

50 100 150 200

Temperature (C)

Rate

(C

/min

)


MOLI Cell #11: 4.0V


Sony Cell: 4.1V

Sanyo

MOLI

Panasonic

Sony(4.1V)

Figure 44. Comparison of onset of ARC thermal runaway for all three commercial cells at 4.0V and the earlier Sony cells at 4.1V (expanded scale).

4.2V Cells

0

200

400

600

800

1000

1200

1400

0 100 200 300 400 500

Temperature (C)

Rate

(C

/min

)

SanyoCell: 4.2V


MOLI Cell #12: 4.2V

Sanyo

Panasonic

MOLI


47

4.2V Cells

0

1

2

3

4

5

6

7

8

9

10

100 120 140 160 180 200

Temperature (C)

Rat

e (

C/m

in)

SanyoCell: 4.2V


MOLI Cell #12: 4.2V

Sanyo

Panasonic

MOLI


4.2V Cells

0

1

2

3

4

5

6

7

8

9

10

50 100 150 200

Temperature (C)

Rat

e (C

/min

)

SanyoCell: 4.2V


MOLI Cell #12: 4.2V

Sony Cell: 4.2V

Sanyo

Panasonic

MOLI

Sony

Figure 47. Comparison of onset of ARC thermal runaway for all three commercial cells and the earlier Sony cells at 4.2V.

48

4.2V Cells

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

50 100 150 200

Temperature (C)

Rat

e (C

/min

)

SanyoCell: 4.2V


MOLI Cell #12: 4.2V

Sony Cell: 4.2V

Sanyo

Panasonic

MOLI

Sony

Figure 48. Comparison of onset of ARC thermal runaway for all three commercial cells and the earlier Sony cells at 4.2V (expanded scale).

4.3V Cells

0

200

400

600

800

1000

1200

1400

0 100 200 300 400 500

Temperature (C)

Rat

e (C

/min

)



Moli Cell: 4.3V

Sanyo

Panasonic

MOLI


49

4.3V Cells

0

1

2

3

4

5

6

7

8

9

10

50 100 150 200

Temperature (C)

Rat

e (C

/min

)



Moli Cell: 4.3V

Sanyo

Panasonic

MOLI


4.3V Cells

0

1

2

3

4

5

6

7

8

9

10

50 100 150 200

Temperature (C)

Ra

te (

C/m

in)



Moli Cell: 4.3V

Sony Cell: 4.3V

Sanyo

Panasonic

MOLI

Sony

Figure 51. Comparison of onset of ARC thermal runaway for all three commercial cells and the earlier Sony cells at 4.3V.

50

4.3V Cells

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

50 100 150 200

Temperature (C)

Rat

e (C

/min

)



Moli Cell: 4.3V

Sony Cell: 4.3V

Sanyo

Panasonic

MOLI

Sony

Figure 52. Comparison of onset of ARC thermal runaway for all three commercial cells and the earlier Sony cells at 4.3V (expanded scale).

51

Table 10. Comparison of Commercial 18650 Li-Ion Cells

Parameter Sony Moli Panasonic Sanyo

Weight (grams) 40.92 47.60 43.15 45.33

Discharge Capacity (C/2 or

less)

1.39 Ah

(0.75 amp)

2.30 Ah

(0.5 amp)

2.14 Ah

(0.75 amp)

2.14 Ah

(0.5 amp)

30s Load

DC Resistance

Ohmic/Total

(ohms)

0.116/0.124

(1.5C/2.25 A)

(4.2V OCV)

0.117 / 0.161

(1C/2.25 A)

(3.8V OCV)

0.103 / 0.127

(1.5C/3.2 A)

(4.2V OCV)

0.126 / 0.152

(1.5C/3.2 A)

(4.2V OCV)

Heat Capacity

(J/g-C)

0.902 0.823 na na

MicroCal Heat (55 C and 4.2 V)

1125 uW 1676 uW na na

MicroCal Heat (55 C and 3.8 V

377 uW 515 uW na

MicroCal Heat (35 C and 4.2 V)

345 uW 509 uW na na

MicroCal Heat (35 C and 3.8 V

142 uW 102 uW na na

Self Discharge

Activation Energy

53.5 kJ/mole@ 3.8V

41.3 kJ/mole@ 4.0V

49.6 kJ/mole@ 4.2V

65.4 kJ/mole@ 3.8V

57.6 kJ/mole@ 4.0V

51.2 kJ/mole@ 4.2V

na na

ARC Onset of Thermal Runaway

(>0.02C/min)

70 C @ 4.1V

60 C @ 4.2V

55 C @ 4.3V

40 C @ 4.4V

40 C @ 4.5V

125 C @ 3.8V

110 C @ 4.0V

105 C @ 4.2V

75 C @ 4.3V

120 C @ 3.8V

114 C @ 4.0V

94 C @ 4.2V

80 C @ 4.3V

119 C @ 3.8V

109 C @ 4.0V

100 C @ 4.2V

90 C @ 4.3 V

ARC High Rate Thermal

195 C @ 3.8V 195 C @ 3.8V 200 C @ 3.8V

52

Runaway

(>10C/min)

200 C @ 4.1V

180 C @ 4.2V

170 C @ 4.3V

170 C @ 4.4V

190 C @ 4.5V

188 C @ 4.0V

180 C @ 4.2V

173 C @ 4.3V

192 C @ 4.0V

179 C @ 4.2V

174 C @ 4.3V

191 C @ 4.0V

176 C @ 4.2V

176 C @ 4.3V

ARC Peak Heating Rate Temperature

Cells cooled before peak runaway

254 C @ 3.8V

303 C @ 4.0V

275 C @ 4.2V

296 C @ 4.3V

258 C @ 3.8V

310 C @ 4.0V

316 C @ 4.2V

leak @ 4.3V

252 C @ 3.8V

269 C @ 4.0V

275 C @ 4.2V

275 C @ 4.3V

ARC Peak Heating Rate

Cells cooled before peak runaway

457 C/min @ 3.8V

934 C/min @ 4.0V

1071C/min @ 4.2V

1136C/min @ 4.3V

645C/min @ 3.8V

1013C/[email protected]

492 C/min@ 3.8V

694 C/[email protected] 1189C/[email protected]

818 C/[email protected] leak @ 4.3V

937 C/min@ 4.3V

53

6.0 Distribution

Brad Irlbeck NASA Lyndon B. Johnson Space Center Mail Code: EP5 Houston, TX 77058 Dr. Eric C. Darcy NASA Lyndon B. Johnson Space Center Energy Systems Division MS: EP5 Houston, TX 77058 Spencer Watson Department of Transportation 400 7th Street Room 8436C Washington, DC 20590 MS-0521 Michael R. Prairie (2520) MS-0613 Daniel H. Doughty (2521) MS-0613 E. Peter Roth (2521) (10) MS-0613 David Johnson (2521) MS-9018 Central Technical Files (8945-1) MS0899 Technical Library, (9616) (2)

54

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