Separator for electric storage device and electric storage device

Patent metadata

Field	Value
Publication number	US-12573718-B2
Application number	US-202218076465-A
Country	US
Kind code	B2
Filing date	Dec 7, 2022
Priority date	Dec 7, 2021
Publication date	Mar 10, 2026
Grant date	Mar 10, 2026

Abstract

[Problem] To provide a separator for electric storage devices that suppresses dendrite short circuits and has excellent thermal stability.[Solution] Provided is a separator for electric storage devices including: (A) a microporous layer mainly composed of (X) isotactic polypropylene; and (B) a microporous layer containing (Y) isotactic polypropylene identical or different from the isotactic polypropylene (X), and (Z) thermoplastic resin different from the isotactic polypropylene (Y). The microporous layer (B) has a lower isotactic polypropylene content than the microporous layer (A), and the thermoplastic resin (Z) has a tensile modulus of from 3 MPa to 500 MPa.

First claim

The invention claimed is:

1 . A separator for electric storage devices comprising:
(A) a microporous layer containing 90 wt % or more of (X) isotactic polypropylene; and (B) a microporous layer containing 85 wt % or more of (Y) isotactic polypropylene identical or different from the isotactic polypropylene (X), and (Z) thermoplastic resin different from the isotactic polypropylene (Y), wherein the microporous layer (B) has a lower isotactic polypropylene content than the microporous layer (A), and the thermoplastic resin (Z) has a tensile modulus of from 3 MPa to 500 MPa.

2 . The separator for electric storage devices according to claim 1 , wherein the thermoplastic resin (Z) has a tensile modulus of from 10 MPa to 200 MPa.

3 . The separator for electric storage devices according to claim 1 , wherein the composition forming the microporous layer (B) has a tensile breaking stress of from 14 MPa to 30 MPa.

4 . The separator for electric storage devices of claim 1 , wherein the separator for electric storage devices, when converted to a thickness of 16 μm, has a permeability of from 50 sec/100 cm 3 to 300 sec/100 cm 3 .

5 . The separator for electric storage devices according to claim 1 , wherein an area-averaged long pore diameter of pores present in the microporous layer (B) in an ND-MD sectional observation of the microporous layer (B) is from 100 nm to 600 nm.

6 . The separator for electric storage devices according to claim 1 , wherein the microporous layer (A) has a melt flow rate (MFR) of 0.9 g/10 min or less.

7 . The separator for electric storage devices according to claim 1 , wherein at least one layer of the microporous layer (A) and at least one layer of the microporous layer (B) are adjacent to each other.

8 . The separator for electric storage devices according to claim 1 , wherein the separator comprises the microporous layer (A) on the outermost layer of both sides thereof.

9 . An electric storage device comprising a positive electrode, a negative electrode, and the separator for electric storage devices according to claim 1 arranged between the positive electrode and the negative electrode.

10 . The electric storage device according to claim 9 , wherein the positive electrode contains lithium iron phosphate as a positive electrode active material.

Assignees

• Celgard Llc
• Asahi Chemical Ind

Inventors

• Uchida Kazunori
• Saito Shun
• Takeda Hisashi

Classifications

• H01M50/489

  Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties · CPC title

• H01M50/46

  Separators, membranes or diaphragms characterised by their combination with electrodes · CPC title

• H01M4/5825

  Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines · CPC title

• H01M50/494

  Tensile strength · CPC title

• H01M50/417

  Polyolefins · CPC title