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US 2026/0279925 A1Published application
Separator for Power Storage Devices, and Power Storage Device
AssigneeAsahi Kasei Kabushiki Kaisha
InventorsYoshiyuki Sugita, Shun Saito, Shohei Mori, Kazunori Uchida
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Abstract
The present invention provides a separator for power storage devices, the separator having a microporous membrane in which a microporous layer (A) containing a polypropylene as a main component and a microporous layer (B) containing a polypropylene as a main component are superposed upon each other, or alternatively, at least one of the microporous layer (A) and the microporous layer (B) is contained. With respect to this separator for power storage devices, the trunk height as calculated from the analysis of an SEM image of an MD-ND cross-section of the microporous membrane is 500 nm to 1,000 nm (inclusive).
Claims14
1:
- A separator for a power storage device comprising a microporous membrane in which a microporous layer (A) containing polypropylene as a principal component and a microporous layer (B) containing polypropylene as a principal component are laminated or at least one of the microporous layer (A) and the microporous layer (B) is included, wherein
- a trunk height calculated from an analysis of an SEM image of an MD-ND cross section of the microporous membrane is 500 nm or greater and 1000 nm or less.
2:
- The separator for a power storage device according to claim 1, wherein an area-average major axis pore diameter of the microporous layer (A) calculated from the analysis of the SEM image of the MD-ND cross section of the microporous membrane is 100 nm or greater and 280 nm or less.
3:
- The separator for a power storage device according to claim 1, wherein an area-average major axis pore diameter of the microporous layer (A) is smaller than an area-average major axis pore diameter of the microporous layer (B).
4:
- The separator for a power storage device according to claim 1, wherein melt tension MtA of the microporous layer (A) at 240° C. is 10 mN or greater and 35 mN or less.
5:
- The separator for a power storage device according to claim 1, wherein a thickness of the microporous membrane is 8 μm or greater and 20 μm or less.
6:
- The separator for a power storage device according to claim 1, wherein a thickness of the microporous layer (A) is 5 μm or less.
7:
- The separator for a power storage device according to claim 1, wherein a molecular weight distribution (Mw/Mn) being a value acquired by dividing a weight-average molecular weight (Mw) of polypropylene in the microporous layer (A) by a number-average molecular weight (Mn) of polypropylene in the microporous layer (A) is 6.0 or greater and 14 or less.
8:
- The separator for a power storage device according to claim 1, wherein a ratio of one or more components with a molecular weight equal to or less than 80,000 in polypropylene in the microporous layer (A) is 10% or greater and 20% or less, and a ratio of one or more components with a molecular weight equal to or greater than 1,500,000 is 10% or greater and 20% or less.
9:
- The separator for a power storage device according to claim 1, wherein an average flow pore diameter of the microporous layer (B) is 20 nm or greater and 25 nm or less.
10:
- The separator for a power storage device according to claim 1, wherein an area-average major axis pore diameter of a surface of the microporous layer (B) is 140 nm or greater and 300 nm or less.
11:
- The separator for a power storage device according to claim 1, wherein a TD thermal contraction rate of the microporous membrane at 105° C. for 1 hour is 5% or less.
12:
- The separator for a power storage device according to claim 1, wherein porosity of the microporous membrane is 40% or greater and 54% or less.
13:
- The separator for a power storage device according to claim 1, wherein melt tension MtA of the microporous layer (A) at 240° C. and melt tension MtB of the microporous layer (B) are different in the microporous membrane.
14:
- The separator for a power storage device according to claim 1, wherein MD tensile strength of the microporous membrane is 1500 kgf/cm2 or greater.