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US 2026/0229702 A1Published application
Separator for Electricity Storage Device and Electricity Storage Device Comprising Same
AssigneeAsahi Kasei Battery Separator Corporation
InventorKazushi Misawa
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Abstract
Provided is a separator for an electricity storage device, the separator including a base material 10 that is a microporous polyolefin membrane containing polyolefin as a main component and a coating layer 20 disposed on at least one surface of the base material 10, wherein the coating layer 20 includes an inorganic filler 1 and a thermoplastic polymer, the thermoplastic polymer includes a particulate polymer 2 protruding from the surface of the inorganic filler portion 1, and a particle size distribution of the particulate polymer 2 has two or more particle diameters.
Claims14
1:
- A separator for an electricity storage device, comprising a substrate which is a polyolefin microporous membrane comprising a polyolefin as a primary component, and
- a covering layer arranged on at least one surface of the substrate, wherein
- the covering layer comprises an inorganic filler and a particulate, thermoplastic polymer,
- the particulate, thermoplastic polymer comprises a protruding particulate polymer, which protrudes from a surface of the inorganic filler portion, and
- a particle size distribution of the particulate, thermoplastic polymer has two or more particle sizes.
2 more elements
2:
- The separator for an electricity storage device according to claim 1, wherein the particle size distribution of the particulate, thermoplastic polymer has a first particle size peak in a range of 1.0-fold or more and 2.0-fold or less a thickness of an inorganic portion of the covering layer, and a second particle size peak in a range larger than the first particle size peak, and a particle size of the second particle size peak is 0.5 μm or more larger than a particle size of the first particle size peak.
3:
- The separator for an electricity storage device according to claim 1, wherein the particle size distribution of the particulate, thermoplastic polymer has a third particle size peak in a range of 0.5 μm or more and 4 μm or less, and a fourth particle size peak in a range larger than the third particle size peak, and a particle size of the fourth particle size peak is 0.5 μm or more larger than a particle size of the third particle size peak.
4:
- A separator for an electricity storage device, comprising a substrate which is a polyolefin microporous membrane comprising a polyolefin as a primary component, and a covering layer arranged on at least one surface of the substrate, wherein the covering layer comprises an inorganic filler and a particulate, thermoplastic polymer,
- the particulate, thermoplastic polymer comprises a protruding particulate polymer, which protrudes from a surface of the inorganic filler portion, and
- the particulate, thermoplastic polymer has at least two glass transition temperatures (Tg).
5:
- The separator for an electricity storage device according to claim 4, wherein the particulate, thermoplastic polymer has a first Tg in a range of 10° C. or higher and 110° C. or lower, has a second Tg in a range of 60° C. or higher and 110° C. or lower, and the second Tg is higher than the first Tg.
6:
- A separator for an electricity storage device, comprising a substrate which is a polyolefin microporous membrane comprising a polyolefin as a primary component, and a covering layer arranged on at least one surface of the substrate, wherein the covering layer comprises an inorganic filler and a particulate, thermoplastic polymer,
- the particulate, thermoplastic polymer comprises a protruding particulate polymer, which protrudes from a surface of the inorganic filler portion,
- the particulate, thermoplastic polymer comprises a first particulate polymer having a particle size which is 0.0 μm or more and less than 1.0 μm larger than a thickness of an inorganic portion of the covering layer,
- the particulate, thermoplastic polymer comprises a second particulate polymer having a particle size which is 1.0 μm or more and 5.0 μm or less larger than the thickness of the inorganic portion of the covering layer, and
- a ratio of a number of the second particulate polymer is 5% or more and 60% or less of the total number of particulate polymers.
2 more elements
7:
- The separator for an electricity storage device according to claim 6, wherein a ratio of a number of the first particulate polymers to the total number of the particulate, thermoplastic polymers is 20% or more and 95% or less.
8:
- The separator for an electricity storage device according to claim 6, wherein a Tg of the second particulate polymer is higher than a Tg of the first particulate polymer, the Tg of the first particulate polymer is 10 to 110° C., and the Tg of the second particulate polymer is 60 to 110° C.
9:
- The separator for an electricity storage device according to claim 1, a ratio of a number of the protruding particulate polymers is 50% or more of a total number of the particulate, thermoplastic polymers contained in the covering layer.
10:
- The separator for an electricity storage device according to claim 1, wherein the particulate, thermoplastic polymer is a primary particle.
11:
- The separator for an electricity storage device according to claim 1, wherein a TD direction thermal shrinkage rate at 130° C. for 1 hour is 5% or less.
12:
- The separator for an electricity storage device according to claim 1, wherein a TD direction thermal shrinkage rate at 150° C. for 1 hour is 5% or less.
13:
- The separator for an electricity storage device according to claim 1, wherein a coefficient of static friction of the covering layer is 0.10 or more and less than 0.40.
14:
- An electricity storage device, comprising the separator for an electricity storage device according to claim 1.