Separator for nonaqueous electrolyte battery, and non-aqueous electrolyte secondary battery

Patent metadata

Field	Value
Publication number	US-9570725-B2
Application number	US-201113881314-A
Country	US
Kind code	B2
Filing date	Oct 21, 2011
Priority date	Oct 29, 2010
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

Disclosed is a separator for a non-aqueous electrolyte battery, the separator including a polyolefin microporous substrate in which a content of polyolefin having a molecular weight of 100,000 or less is from 10% by mass to 25% by mass relative to a total amount of polyolefin, and a heat resistant porous layer that is formed on one or both sides of the polyolefin microporous substrate and that includes a heat resistant polymer, wherein a maximum value of S, which is represented by the following formula (1), is 0.8 or more, and a temperature exhibiting the maximum value of S is from 130° C. to 155° C.:

S=d (log R )/ dT   Formula (1):

wherein R represents a resistance (ohm·cm 2 ) of a cell, and T represents a temperature (° C.), in a measurement using a battery that includes the cell that is provided with a separator for a non-aqueous electrolyte battery, at a temperature rising rate of 1.6° C./min.

First claim

The invention claimed is:

1. A separator for a non-aqueous electrolyte battery, the separator comprising:
a polyolefin microporous substrate in which a content of polyethylene having a molecular weight of 100,000 or less is from 10% by mass to 25% by mass relative to a total amount of polyolefin, and
a heat resistant porous layer that is formed on and directly contacts one or both sides of the polyolefin microporous substrate and that includes a heat resistant polymer that has a crystal melting point of 200° C. or higher as measured by differential scanning calorimetry, wherein
a maximum value of S, which is represented by the following formula (1), is 1.2 or more, and
a temperature exhibiting the maximum value of S is from 130° C. to 155° C.:
S=d (log R )/ dT   Formula (1):

wherein, in formula (1), R represents a resistance (ohm·cm 2 ) of a cell, and T represents a temperature (° C.), in a measurement using a battery that includes the cell that is provided with a separator for a non-aqueous electrolyte battery, at a temperature rising rate of 1.6° C./min,
wherein in the polyolefin microporous substrate, a polyethylene content relative to the total amount of polyolefin is 90% by mass or more, and
wherein the polyolefin microporous substrate has a porosity of from 20% to 60%, and a pore diameter as measured by a specific surface area method of from 10 nm to 150 nm.

2. The separator for a non-aqueous electrolyte battery according to claim 1 , wherein a difference between the temperature exhibiting the maximum value of S and a lowest temperature among temperatures exhibiting a value of S of 0.8 is 5° C. or less.

3. The separator for a non-aqueous electrolyte battery according to claim 1 , wherein the heat resistant porous layer has a porosity of from 30% to 90%, and a pore diameter as measured by a specific surface area method of from 50 nm to 250 nm.

4. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, and a separator for a non-aqueous electrolyte battery according to claim 1 that is disposed between the positive electrode and the negative electrode, the battery obtaining an electromotive force through doping and dedoping of lithium.

5. The non-aqueous electrolyte secondary battery according to claim 4 , wherein a difference between the temperature exhibiting the maximum value of S and a lowest temperature among temperatures exhibiting a value of S of 0.8 is 5° C. or less.

6. The non-aqueous electrolyte secondary battery according to claim 4 , wherein the heat resistant porous layer has a porosity of from 30% to 90%, and a pore diameter as measured by a specific surface area method of from 50 nm to 250 nm.

Assignees

• Yoshitomi Takashi
• Teijin Ltd

Inventors

• Yoshitomi Takashi

Classifications

• H01M50/403

  Manufacturing processes of separators, membranes or diaphragms · CPC title

• H01M50/451

  comprising layers of only organic material and layers containing inorganic material · CPC title

• H01M50/457

  comprising three or more layers · CPC title

• H01M50/406

  Moulding; Embossing; Cutting · CPC title

• H01M50/423

  Polyamide resins · CPC title