Separator, method of manufacturing the same and battery using the same

Patent metadata

Field	Value
Publication number	US-10230090-B2
Application number	US-201514745608-A
Country	US
Kind code	B2
Filing date	Jun 22, 2015
Priority date	Jun 24, 2014
Publication date	Mar 12, 2019
Grant date	Mar 12, 2019

Abstract

A polyolefin-based porous separator, including a first polyolefin-based porous film on a first surface of a second polyolefin-based porous film, and a third polyolefin-based porous film on a second surface of the second polyolefin-based porous film, each of the first and third polyolefin-based porous films containing inorganic particles having an average particle size of 10 nm to 100 nm, a thickness ratio of the first polyolefin-based porous film, the second polyolefin-based porous film, and the third polyolefin-based porous film being 0.5 to 1.5:1 to 6:0.5 to 1.5, and thermal shrinkage rates of the separator in a machine direction and a transverse direction measured after standing at 120° C. for 1 hour each being 5% or less, and air permeability of the separator being 250 sec/100 cc or less.

First claim

What is claimed is:

1. A polyolefin-based porous separator, comprising:
a first polyolefin-based porous film on a first surface of a second polyolefin-based porous film, and a third polyolefin-based porous film on a second surface of the second polyolefin-based porous film,
each of the first and third polyolefin-based porous films containing inorganic particles, an average particle size of all the inorganic particles in the first and third polyolefin-based porous films being 10 nm to 100 nm,
wherein each of the first to third polyolefin-based porous films includes a polyolefin-based resin comprising high density polyethylene (HDPE) having a viscosity average molecular weight (Mv) of 100,000 to 900,000 and ultrahigh molecular weight polyethylene (UHMWPE) having a viscosity average molecular weight of 900,000 or more,
wherein each of the first and third porous films includes 18.7 wt % to 59.2 wt % of the ultrahigh molecular weight polyethylene based on a total weight of each of the first and third porous films,
wherein the second porous film includes 15 wt % to 20 wt % of the ultrahigh molecular weight polyethylene based on a total weight of the second porous film,
wherein a thickness ratio of the first polyolefin-based porous film, the second polyolefin-based porous film, and the third polyolefin-based porous film being 0.5 to 1.5:1 to 6:0.5 to 1.5,
wherein thermal shrinkage rates of the separator in a machine direction and a transverse direction measured after standing at 120° C. for 1 hour each being 5% or less, and air permeability of the separator being 250 sec/100 cc or less, and
wherein one or more of the first and third porous films includes 40 wt % to 70 wt % of the inorganic particles based on a total weight of a composition for forming the first porous film or a composition for forming the third porous film.

2. The polyolefin-based porous separator as claimed in claim 1 , wherein each of the first to third polyolefin-based porous films includes pores caused by stretching.

3. The polyolefin-based porous separator as claimed in claim 1 , wherein a thickness change T represented by the following Equation 1 is 20% or less:
T (%)=[ T 1 −T 2 ]/T 1 ×100,  [Equation 1]

wherein T 1 is a thickness of the polyolefin-based porous separator before heating and pressing, and T 2 is a thickness of the polyolefin-based porous separator after heating and pressing at 90° C. and 2.2 MPa for 5 minutes.

4. The polyolefin-based porous separator as claimed in claim 1 , wherein air permeability measured after heating and pressing the polyolefin-based porous separator at 90° C. and 2.2 MPa for 5 minutes is 500 sec/100 cc or less.

5. The polyolefin-based porous separator as claimed in claim 1 , wherein:
tensile strength of the polyolefin-based porous separator in each of the machine direction and the transverse direction is 900 kgf/cm 2 or more, and
a thermal shrinkage rate measured in each of the machine direction and the transverse direction after standing at 105° C. for 1 hour is 0.1% or less.

6. The polyolefin-based porous separator as claimed in claim 1 , wherein an electrolyte solution absorption amount measured after dipping the polyolefin-based porous separator in an electrolyte solution at 18° C. for 60 minutes is 300 mg or more per 1 g of the polyolefin-based porous separator.

7. The polyolefin-based porous separator as claimed in claim 1 , wherein an electrolyte solution absorption ratio represented by the following Equation 2 is 1.5 or more:
Electrolyte solution absorption ratio( A )=[ A 1 /A 2 ]  [Equation 2]

wherein A 1 is an electrolyte solution absorption amount per 1 g of the polyolefin-based porous separator including the first to third porous films, A 2 is an electrolyte solution absorption amount per 1 g of an inorganic separator that contains a polyolefin-based resin and does not contain inorganic particles, and A 1 and A 2 are measured after dipping the polyolefin-based porous separator in an electrolyte solution at 18° C. for 60 minutes.

8. An electrochemical battery, comprising:
a cathode,
an anode,
an electrolyte, and
a separator interposed between the cathode and the anode, the separator being the polyolefin-based porous separator as claimed in claim 1 .

9. The electrochemical battery as claimed in claim 8 , wherein the electrochemical battery is a secondary battery.

10. The electrochemical battery as claimed in claim 9 , wherein the secondary battery is a lithium secondary battery.

11. A method of manufacturing a polyolefin-based porous separator, the method comprising:
forming a first polyolefin-based porous film on a first surface of a second polyolefin-based porous film by melt-kneading and extruding a polyolefin-based resin composition and a plasticizer to manufacture a first cooled and solidified sheet, and
forming a third polyolefin-based porous film on a second surface of the second polyolefin-based porous film by melt-kneading and extruding a polyolefin-based resin composition and the plasticizer to manufacture a second cooled and solidified sheet,
each of the first and third polyolefin-based porous films containing inorganic particles, an average particle size of all the inorganic particles in the first and third polyolefin-based porous films being 10 nm to 100 nm,
wherein one or more of the first or third porous film includes 40 wt % to 70 wt % of the inorganic particles based on a total weight of a composition for forming the first porous film or a composition for forming the third porous film
a thickness ratio of the first polyolefin-based porous film, the second polyolefin-based porous film, and the third polyolefin-based porous film being 0.5 to 1.5:1 to 6:0.5 to 1.5,
wherein each of the first to third polyolefin-based porous films comprises a polyolefin-based resin comprising high density polyethylene (HDPE) having a viscosity average molecular weight (Mv) of 100,000 to 900.000 and ultrahigh molecular weight polyethylene (UHMWPE) having a viscosity average molecular weight of 900,000 or more,
wherein each of the first and third odorous films includes 18.7 wt % to 59.2 wt % of the ultrahigh molecular weight polyethylene based on a total weight of each of the first and third porous films, and
wherein the second porous film includes 15 w/t % to 20 w/t % of the ultrahigh molecular weight polyethylene based on a total weight of the second porous film.

12. The method as claimed in claim 11 , wherein before the melt-kneading, a composition for forming the first polyolefin-based porous film and a composition for forming the third polyolefin-based porous film are formed by pre-mixing the polyolefin-based resin compositions, the inorganic particles, and the plasticizer with each other.

13. The method as claimed in claim 11 , wherein the first polyolefin-based porous film, the second polyolefin-based porous film, and the third polyolefin-based porous film are formed by co-extrusion or heat-fusion.

14. The method as claimed in claim 11 , further comprising:
stretching the solidified sheets in a machine direction and a transverse direction to form pores, and
extracting the plasticizer.

15. The method as claimed in claim 14 , wherein the stretching is performed under conditions including a temperature of 100° C. to 130° C., a stretching ratio in the machine direction of 4 to 10 times, and a stretching ratio in the transverse direction of 4 to 10 times.

16. The method as claimed in claim 14 , wherein the solidified sheets from which the plasticizer is extracted are heat-set in at least one axis direction at 110° C. or more.

Assignees

• Samsung Sdi Co Ltd

Inventors

• Lee Sang Ho
• Kim Kee Wook
• Kim Yun Gi
• Lee Jung Seong
• Jang Jung Sue
• Chung Jun Ho
• Cho Jae Hyun
• Hong Dae Hyun

Classifications

• B29C48/08 Primary

  flexible, e.g. films · CPC title

• B29C48/914

  Cooling drums · CPC title

• B29C48/37

  Gear pumps · CPC title

• H01M10/052

  Li-accumulators · CPC title

• B29C48/92

  Measuring, controlling or regulating · CPC title