Amprius Passes U.S Army Nail Penetration Test with Unprecedented 390 Wh/kg Battery Cell

An independent third-party testing lab has validated Amprius’ 390 Wh/kg polymer electrolyte cell by successfully passing the nail penetration test per the requirements of section 4.7.4.4. of the MIL-PRF-32383 (Military Performance Specification).
The test is used to determine the feasibility of a specific product in combat scenarios. Cells tested in accordance with 4.7.4.4. shall not burn or explode, and the external temperature of each test sample shall not be greater than 338 degrees Fahrenheit (170 degrees Celsius) when penetrated by sharp objects.
When conducting the test, a 0.113-inch diameter stainless steel nail is driven through a fully charged cell at a prescribed speed. The cell is deemed to have passed if there is no smoke or flame following the nail penetration. The test video in real time, slow motion and infrared
Amprius’ innovative polymer electrolyte prevents the penetrating nail from creating a low resistance short circuit, as indicated by the minimal increase in the cell temperature after penetration and only a small decrease in cell voltage. After nail penetration the cell is still functioning and providing power, a critical capability for soldier wearable batteries.