A separator for lithium battery and a lithium battery using the same

Abstract

This invention provides a separator for lithium batteries and a lithium battery using the same. The lithium battery includes a wound cell, which includes a positive electrode and a separator. The region of the separator substrate extending beyond the width of the positive electrode is designated as a margin region, while other regions are designated as normal coating regions. The margin region and the normal coating regions are respectively provided with a first coating layer and a second coating layer. The thickness 'a' of the first coating layer and the thickness 'b' of the second coating layer satisfy 1.1 ≤ a / b ≤ 2. This invention, through differentiated coating design, specifically thickens the coating layer in the margin region of the separator substrate, ensuring that the thickness 'a' of the coating layer in the margin region and the thickness 'b' of the coating layer in the normal coating region satisfy 1.1 ≤ a / b ≤ 2. This significantly improves the thermal stability of the margin region of the separator without increasing the diameter or thickness of the wound cell or reducing the cycle stability of the lithium battery. It also reduces the safety risk of short circuits caused by separator shrinkage during lithium battery short circuits, thereby improving the safety performance of the lithium battery.

Images