This section provides hypervelocity impact test data for two types of batteries: Lithium-Ion (Li-Ion) and Nickel Hydrogen (Ni-H2) batteries. The impact tests were directed by the NASA Johnson Space Center Hypervelocity Impact Technology (HVIT) group in Houston Texas, and were performed at the NASA White Sands Test Facility (WSTF)

Christiansen, E. L.

Hyde, Jimx

Miller, J. E.

NASA Technical Reports Server

NASA Johnson Space Center, E.L. Christiansen and J.E. Miller 22 Feb 2016 
IADC Vulnerability Report, IT32-13 
 
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1 Battery 
This section provides hypervelocity impact test data for two types of batteries: Lithium-Ion 
(Li-Ion) and Nickel Hydrogen (Ni-H2) batteries. The impact tests were directed by the NASA 
Johnson Space Center Hypervelocity Impact Technology (HVIT) group in Houston Texas, and 
were performed at the NASA White Sands Test Facility (WSTF). 
1.1 Damage Mode 
Li-ion batteries have been selected to replace Ni-H2 batteries for the International Space 
Station (ISS) program to meet the energy storage demands while the ISS is in the Earth’s 
shadow during its approximate 90 minute low Earth orbit. ISS battery boxes are located on the 
exterior of ISS and are exposed to micrometeoroid and orbital debris (MMOD) impacts. 
Dedicated MMOD shields on the battery boxes reduce failure risk to an acceptable level.  
Hypervelocity impact testing was performed to develop and verify the MMOD shields 
protecting the Li-ion battery cells (consisting of aluminum honeycomb panel and additional 
fabric layers), as well as to understand the consequences if at some point in the operation of 
the ISS a MMOD particle overwhelms the shielding designed for the Li-ion battery packs and 
damage battery cells to cause a short circuit or a thermal runaway of the cell. Thermal runaway 
events have been experienced in terrestrial applications of the Li-ion battery and have the 
potential to propagate to neighboring cells. If thermal runaway occurs in one cell, even 
undamaged adjacent cells can over-heat and transition into thermal runaway conditions. Fully 
charged Li-ion battery cells that are representative of two possible candidates for ISS 
operations were impacted in hypervelocity impact tests by projectiles that easily defeat the 
designed shielding for the ISS external battery packs. Even though this is a low probability 
event, the tests were performed to evaluate if the proposed design prevented the loss of 
multiple cells due to propagation of thermal runaway from the impacted cell to adjacent cells. 
https://ntrs.nasa.gov/search.jsp?R=20170009404 2019-08-29T23:32:12+00:00Z
NASA Johnson Space Center, E.L. Christiansen and J.E. Miller 22 Feb 2016 
IADC Vulnerability Report, IT32-13 
 
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Hypervelocity impact tests were also performed on Ni-H2 batteries representative of ISS 
Ni-H2 battery cells, which are contained within a box that is made from aluminum honeycomb 
sandwich panels. The Ni-H2 battery cells were fully-charged and pressurized with hydrogen to 
60 atm prior to the impact tests. The failure mode of concern is a rupture and fragmentation of 
the pressure shell of Ni-H2 battery cell, and propagation to neighboring cells. 
1.2 Li-Ion Impact Experiments 
Hypervelocity impact conditions on Li-ion cells are summarized in Table 1.2-1. Each test 
article used two separate Li-ion battery cells but only one was targeted. A second cell is 
included to determine if failure can propagate to a nearby undamaged cell. The impact 
locations were typically at the terminal end of the battery cells, although some shots to the side 
of the Li-ion battery were also performed. Two different types of Li-ion batteries were tested 
with similar results. When penetrated, the impacted Li-ion battery typically increases in 
temperature while the cell contents are ejected and can in some cases auto-ignite. The 
neighboring cell will in most cases increase in temperature, but only occasionally will the 
temperature increase substantially resulting in failure of the undamaged cell due to thermal 
runaway. A sequence of images of the Li-ion battery response from one test is shown in Figure 
1.2-1. This test resulted in a visible deflagration as the impacted cell contents were 
energetically ejected over a several second time period following cell penetration. The 
aluminum honeycomb panel in front of the cell was severely melted due to the expelled cell 
material (Figure 1.2-2a). The neighboring cell did not transition into thermal runaway. Figure 
1.2-2b shows the cells after the impact test. 
  
NASA Johnson Space Center, E.L. Christiansen and J.E. Miller 22 Feb 2016 
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Table 1.2-1. Li-Ion cell impact conditions. 
Test # Projectile 
Diameter 
(mm) 
Impact 
Obliquity 
(°) 
Impact 
Speed 
(km/s) 
Cell Damage 
Measurements 
(mm) 
HITF12143 10.0 0 6.86 Primary cell-Perforated with peak temperature of 184°C 
Secondary cell-No ignition or thermal runaway 
HITF12144 10.0 0 7.02 Primary cell-Perforated, no ignition, peak temperature 194°C 
Secondary cell- Thermal runaway peaking at 531°C 
HITF12145 10.0 30 7.05 Primary cell-No Perforation 
Secondary cell-No Perforation 
HITF12147 13.5 45 6.88 Primary cell-Perforated with peak temperature of 193°C 
Secondary cell- Thermal runaway peaking at 315°C 
HITF12148 10.0 0 7.19 Primary cell-Perforated, no ignition 
Secondary cell-No ignition or thermal runaway 
 
  
  
  
Figure 1.2-1. HITF12143 visible video frames at 1s-2s intervals after impact. 
NASA Johnson Space Center, E.L. Christiansen and J.E. Miller 22 Feb 2016 
IADC Vulnerability Report, IT32-13 
 
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a) 
 
b) 
 
Figure 1.2-2. After test imagery of HITF12143 a) shield with 9.5cm diameter through-hole, 
and b) cell close-up with impacted cell on right showing molten material from cell interior that 
was ejected and deposited on exterior of cell. 
1.3 Ni-H2 Cell Impact Experiments  
Ni-H2 battery hypervelocity impact tests were performed on a legacy configuration of the 
ISS orbital replacement unit (ORU) battery assembly as shown in Figure 1.3-1. Thirty-eight 
cylindrical battery cells are contained in the enclosure as seen in Figure 1.3-1b. The Ni-H2 
battery cells are constructed from Inconel 718 with minimum thicknesses in the cylinder of 0.8 
mm and the dome of 0.65 mm. 
a) 
 
b) 
 
Figure 1.3-1 a) ISS Ni-H2 battery ORU and b) ORU subassembly without enclosure. 
 
NASA Johnson Space Center, E.L. Christiansen and J.E. Miller 22 Feb 2016 
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The Ni-H2 cell considered in this testing generates hydrogen gas in the free cell volume as 
a result of the chemical reactions that occur during charging.  The hydrogen accumulates up 
to a design pressure of 6 MPa which indicates 100% state of charge (SOC) for the rated 81 
ampere-hour (Ah). The cells contain an aqueous potassium hydroxide (KOH) electrolyte 
solution.  The cells were proof tested to 10.3 MPa and have a burst pressure of 37.2 MPa. The 
burst factor for this cell is 6 (burst pressure/operating pressure). In the event of over-
pressurization, the cells are designed to leak before burst. Impact testing was performed to 
determine if the vessel fragments after penetration and to assess if there are any adverse 
reactions with the electrode materials, thermal events or cascade failure responses. 
The enclosure consists of an aluminum honeycomb panel with 0.4 mm facesheets 
separated by 12.7 mm thick honeycomb that is covered by a multi-layer insulation blanket 
(0.086 g/cm2).  
The Ni-H2 impact conditions are summarized in Table 1.3-1. These tests impacted through 
the aluminum honeycomb enclosure, and were targeted to consider three basic locations on 
the Ni-H2 battery: in the dome, into the terminals on the top of the domes, and into the side. 
Various aluminum and steel projectile diameters were used in the tests, at impact speeds of 7 
km/s and impact angles of 0° and 45° to the normal of the honeycomb panel. None of the tests 
resulted in fragmentation of the cells. No thermal events or cascading failures resulted to 
neighboring cells.  The largest perforations are shown in Figure 1.3-2a (test HITF13144) and 
Figure 1.3-2b (test HITF13165). Generally, the response to cell perforation was that the Ni-H2 
cell vented and the voltage across the terminals declined until the cell could no longer maintain 
current over a load. In one case, the battery box cover was deformed because cell venting 
occurred so quickly that the box pressure increased sufficiently to deform the cover. 
  
NASA Johnson Space Center, E.L. Christiansen and J.E. Miller 22 Feb 2016 
IADC Vulnerability Report, IT32-13 
 
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Table 1.3-1 Ni-H2 impact conditions. 
Test # Impact 
Location 
Projectile 
Diameter 
(mm) 
Impact 
Obliquity 
(°) 
Impact 
Speed 
(km/s) 
Cell Damage 
Measurements 
(mm) 
HITF13144 Dome 5.0 0 6.66 11.5 x 10.0 Perforation 
HITF13145 Dome 4.0 0 6.86 1.0 x 1.5 Perforation 
HITF13146 Dome 3.8 0 7.09 1.5 x 2.4 Perforation 
HITF13147 Dome 3.4 0 7.09 2.4 x 3.5 Perforation 
HITF13148 Dome 3.0 0 7.00 2.5 x 1.5 Perforation 
HITF13149 Dome 2.8 0 7.19 No Perforation 
HITF13151 Terminal 2.9 0 7.19 No Perforation 
HITF13152 Terminal 3.1 0 7.12 No Perforation 
HITF13153 Terminal 3.3 0 6.85 No Perforation 
HITF13154 Terminal 4.2 45 7.13 1.6 x 1.2 Perforation 
HITF13155 Terminal 3.0* 45 7.00 1.5 x 1.5 Perforation 
HITF13158 Dome 5.0 45 7.13 2.0 x 2.0 Perforation 
HITF13159 Dome 4.0 45 7.00 No Perforation 
HITF13160 Dome 4.2 45 7.07 1.8 x 08 Perforation 
HITF13162 Terminal 5.0 0 7.05 7.5 x 7.0 Perforation 
HITF13163 Terminal 4.8 0 7.07 No Perforation 
HITF13164 Terminal 5.1 0 7.04 3.0 x 1.0 Perforation 
HITF13165 Terminal 3.8* 0 6.87 18.0 x 8.0 Perforation 
HITF13174 Side 4.1 45 7.04 1.0 x 4.0 Perforation 
HITF13175 Side 3.9 45 7.04 No Perforation 
 
a) 
 
b) 
 
Figure 1.3-2 ISS a) HITF13144 and b) HITF13165. 
1.4 Recommendations 
The use of rechargeable batteries in orbital spaceflight requires consideration of the 
uncontrolled energy release from a cell, which is dependent on the type of cell. Impact 
NASA Johnson Space Center, E.L. Christiansen and J.E. Miller 22 Feb 2016 
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experiments have evaluated the failure mechanisms of the pressurized Ni-H2 battery cell and 
the charged Li-Ion battery cell. For the operational design of the Ni-H2 battery like those used 
on the ISS, the hydrogen gas will vent on perforation of the battery vessel; but unusual thermal 
events or catastrophic rupture did not occur. The ISS Ni-H2 battery cells have a relatively high 
burst factor of 6. When pressurized battery cells are used in other spacecraft, attention to the 
burst factor of the cell should be taken into account. 
Impact tests on Li-ion battery cells demonstrated an energetic release of energy when 
shielding is overmatched and the cell is penetrated. The impacted cell typically will overheat 
and will vent/eject the internal contents of the cell, including molten metal, rapidly after impact 
(within a few seconds). In some cases the venting material will auto-ignite, even in the vacuum 
environment of the test chamber. Depending on the design of the battery cell enclosure, 
neighboring Li-ion cells can also experience increases in temperature and can fail due to 
thermal runaway.  
Shielding for batteries could be selected based upon the type of cell to be protected, typical 
failure modes and the acceptability for loss of battery cells. Supplemental shielding for Li-ion 
batteries should be designed to meet survivability requirements without allowing perforation of 
the cell wall. Shield and battery designs should be verified by test to ensure they meet 
protection requirements. 
 


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