design safety used in nasa’s human-rated primary lithium … · 2019. 8. 29. · j. jeevarajan,...
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J. Jeevarajan, Ph.D. /NASA-JSC
Design Safety Used in NASA’s Human-rated
Primary Lithium Batteries
J. Jeevarajan, Ph.D.
NASA-JSC
The 2013 NASA Battery Workshop
Huntsville, AL
November, 2013
https://ntrs.nasa.gov/search.jsp?R=20140003135 2019-08-29T14:47:01+00:00Z
Safety Requirements
• NASA’s human-rated safety requirements
– Two-failure tolerance to catastrophic failures (JSC 20793)
• Catastrophic for human-rating requires
– No electrolyte venting that would cause permanent injury to crew or
loss of vehicle or mission
– Electrolytes that can cause permanent injury are rated as
Toxicology level 2 for NASA human-rated missions
• Lithium primary with an organic electrolyte and li-ion with organic
electrolytes have a salt that is an irritant and corrrosive giving these
electrolytes a Tox2 rating
• The requirement therefore dictates that two-failure tolerance
should be provided for all hazards that can lead to venting
(electrolyte liquid), fire and thermal runaway.
– For primary batteries this translates to two-failure tolerance to
inadvertent charge, overdischarge into reversal, external and
internal shorts, extreme temperatures especially high temps
– Since no external controls exist for internal shorts, a design for
minimum risk approach is used to mitigate that hazard.
J. Jeevarajan, Ph.D. /NASA-JSC
Recommendations for Protective Features to
Prevent Catastrophic Failures
• Inadvertent charge shall be prevented
– Between parallel primary lithium cells/cell strings
– Between primary lithium cells and other charging sources
• Overdischarge into reversal
– Prevent unbalanced cell condition (need for cell
matching)
– Prevent taking cells into low voltages and/ or
reversal
J. Jeevarajan, Ph.D. /NASA-JSC
Cells in parallel Cell strings in
parallel
Redundancy in
the case of
mission critical
applications
Recommendations for Protective Features to
Prevent Catastrophic Failures
• External Shorts
– High and low impedance short protection required
– Fuses, PTCs, polyswitches, etc. shall be rated for the voltage,
current and temperature of battery design and application as well
as environment
• Internal Short
– Stringent cell and battery level screening (OCV, CCV, dimensions,
mass, Re)
– Cell matching
– Rigorous battery flight acceptance testing that includes (vacuum)
leak check and vibration screening with stringent pass/fail criteria for
OCV, CCV (Re) and mass
J. Jeevarajan, Ph.D. /NASA-JSC
J. Jeevarajan, Ph.D. /NASA-JSC
AED LiMnO2 battery AED for International Space Station (ISS) Human-rated
Application (Flown in 2008 and has been on-orbit since)
Original Design: Ultralife 5/4 C (U10021) high-rate cells; 4 in
series; 1 diode in parallel to each cell; 2 TCOs one between cells
1 & 2 and one between cells 3 & 4
12 V; 6.2 Ah
Original AED Battery Design
J. Jeevarajan, Ph.D. /NASA-JSC
Inadvertent Charge on Single Cell
0
2
4
6
8
10
12
14
0 2000 4000 6000 8000 10000 12000
Time (s)
Vo
ltag
e (
V)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Cu
rren
t (A
)
Voltage
Current
0
10
20
30
40
50
60
70
80
90
0 2000 4000 6000 8000 10000 12000
Time (s)
Te
mp
era
ture
(d
eg
C)
TC1
TC2
Charge Current: 2.0A
Duration: 6 hours
Limit: 12 V
J. Jeevarajan, Ph.D. /NASA-JSC
Overdischarge of Unbalanced String of Four Cells
-10
-5
0
5
10
15
0 100 200 300 400 500 600
Time (seconds)
Vo
lta
ge
(V
)
0.0
2.0
4.0
6.0
8.0
10.0
Cu
rre
nt
(A)
cell 16-1
cell 16-2
cell 16-3
cell 16-4
String 16 V
Current
Cell 4
Load: 6.9 A
J. Jeevarajan, Ph.D. /NASA-JSC
Overdischarge of Unbalanced String of Four Cells
0
100
200
300
400
0 200 400 600 800 1000 1200
Time (seconds)
Te
mp
era
ture
(d
eg
C)
cell 16-1
cell 16-2
cell 16-3
cell 16-4
Load: 6.9 A
J. Jeevarajan, Ph.D. /NASA-JSC
Overdischarge Into Reversal of Single Cell
-5
-3
-1
1
3
5
0 10 20 30 40 50 60 70 80 90
Time (minutes)
Cu
rren
t (A
)
-5
-4
-3
-2
-1
0
1
2
3
4
5
Vo
ltag
e (
V)
Current
Voltage
Load: 4.5 A
Max Temp : 80 deg C
J. Jeevarajan, Ph.D. /NASA-JSC
Overdischarge of Unbalanced String of Four Cells
-8
-6
-4
-2
0
2
4
0 500 1000 1500 2000 2500 3000
Time (seconds)
Cell V
olt
ag
e (
V)
cell 19-1
cell 19-2
cell 19-3
cell 19-4
Load: 4.5 A
J. Jeevarajan, Ph.D. /NASA-JSC
0
50
100
150
200
250
300
350
0 500 1000 1500 2000 2500 3000
Time (seconds)
Te
mp
era
ture
(d
eg
C)
cell 19-1
cell 19-2
cell 19-3
cell 19-4
Overdischarge of Unbalanced String of Four Cells
Load: 4.5 A
J. Jeevarajan, Ph.D. /NASA-JSC
Heat-to-Vent Test on Single LiMnO2 AED Cell
0
100
200
300
400
500
600
700
800
0 2000 4000 6000 8000 10000 12000 14000
Time (seconds)
Tem
pe
ratu
re (
deg
C)
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
Vo
lta
ge (
V)
TC 1
TC 2
OCV
J. Jeevarajan, Ph.D. /NASA-JSC
Heat-to-Vent of Single Cell
• Originally, the cell was in the clamp on the ring stand.
• the cell went to the right, the feedthrough went towards the top to the left,
• the false cover went to the bottom left,
• the brick on the lower center was in alignment with the brick next to it (the
bricks are 5 1/2 x 5 1/2 x 2 3/8 in.(14 x 14 x 6 cm) and weigh 5.8 lb (2.6 kg))
X
X
J. Jeevarajan, Ph.D. /NASA-JSC
Simulated Internal Short (Crush) on Single Cell
0
200
400
600
800
1000
1200
0 200 400 600 800 1000
Time (seconds)
Tem
pera
ture
(d
eg
C)
-1
0
1
2
3
4
5
Vo
ltag
e (
V)
TC1
TC2
OCV
J. Jeevarajan, Ph.D. /NASA-JSC
External Short Circuit Test on a Single Cell
0
5
10
15
20
25
30
35
40
45
0 1000 2000 3000 4000 5000 6000 7000 8000 9000
Time (seconds)
Cu
rren
t (A
)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Vo
ltag
e (
V)
Current
Voltage
Load : 50 mohm
J. Jeevarajan, Ph.D. /NASA-JSC
External Short Circuit Test on a Single Cell
0
10
20
30
40
50
60
70
80
90
0 1000 2000 3000 4000 5000 6000 7000 8000 9000
Time (seconds)
Te
mp
era
ture
(d
eg
C)
TC1
TC2
J. Jeevarajan, Ph.D. /NASA-JSC
External Short on a String of Four Cells
-10
-8
-6
-4
-2
0
2
4
0 100 200 300 400 500
Time (seconds)
Vo
lta
ge
(V
)
Cell 10-1
Cell 10-2
Cell 10-3
Cell 10-4
J. Jeevarajan, Ph.D. /NASA-JSC
External Short on a String of Four Cells
0
40
80
120
160
200
240
0 100 200 300 400 500
Time (seconds)
Te
mp
era
ture
(d
eg
C) Cell 10-1
Cell 10-2
Cell 10-3
Cell 10-4
J. Jeevarajan, Ph.D. /NASA-JSC
External Short on a String of Four Cells
J. Jeevarajan, Ph.D. /NASA-JSC
Summary of Test Results
• Single cell tests were benign for external short, inadvertent charge and overdischarge into reversal up to 4.5 A.
– At lower current loads cells die (may be due to excessive dendrite formation) benignly.
• String level external short circuits lead to an unbalanced overdischarge, with one cell going into reversal. The result is catastrophic violent venting.
• Unbalanced string overdischarges at different currents causes catastrophic violent venting also.
• Heat-to-vent is very dramatic displaying violent venting
• Simulated internal short is also catastrophic and displays violent venting.
• Battery is not UL-rated; hence does not have dual-fault tolerance or tolerance to inherent cell tolerance to failures
Design Change as Recommended by NASA Battery
Safety
J. Jeevarajan, Ph.D. /NASA-JSC
Original AED Battery Design
NASA JSC AED Battery Design (currently on ISS)
Summary and Conclusions
• Single cell tests were benign for external short, inadvertent charge and overdischarge into reversal up to 4.5 A.
– At lower current loads cells die (may be due to excessive dendrite formation) benignly.
• String level external short circuits lead to an unbalanced overdischarge, with one cell going into reversal. The result is catastrophic violent venting.
• Unbalanced string overdischarges at different currents causes catastrophic violent venting also.
• Heat-to-vent is very dramatic displaying violent venting
• Simulated internal short is also catastrophic and displays violent venting.
• Battery is not UL-rated; hence does not have dual-fault tolerance or tolerance to inherent cell tolerance to failures
• Battery Design for NASA JSC’s human-rated application for use on ISS was changed to include two bypass diodes per cell to provide for two-failure tolerance to overdischarge into reversal (and external short) hazards.
J. Jeevarajan, Ph.D. /NASA-JSC
J. Jeevarajan, Ph.D. /NASA-JSC
Acknowledgment
• Applied Power International
• Space and Life Sciences Directorate, NASA-JSC