Nail penetration test

For the nail penetration test, three types of pouch cells with different separators were assembled. The positive electrode is LiMn_1/3Ni_1/3Co_1/3O₂, the negative electrode is graphite, and the separator is PP-PE-PP or coated PE or coated nonwoven. At the fully charged state of 4.3V, a 4.5mm diameter nail was pushed into the cell at a penetration speed of 20mm/s. The results of the nail penetration test varied significantly depending on the type of separator.