Polymer composite membrane, preparation method for same, and lithium-ion battery including same

Patent metadata

Field	Value
Publication number	US-11264674-B2
Application number	US-201716328601-A
Country	US
Kind code	B2
Filing date	Aug 14, 2017
Priority date	Aug 29, 2016
Publication date	Mar 1, 2022
Grant date	Mar 1, 2022

Abstract

The disclosure relates to the field of lithium-ion batteries, and discloses a polymer composite membrane and a method for preparing same. The disclosure further includes a lithium-ion battery for which the foregoing polymer composite membrane is used. The polymer composite membrane includes a porous base membrane and a heat-resistant fiber layer covering at least one side surface of the porous base membrane, where materials of the heat-resistant fiber layer contain a first polymeric material and a second polymeric material.

First claim

What is claimed is:

1. A polymer composite membrane,
comprising a porous base membrane;
a heat-resistant fiber layer covering at least one side surface of the porous base membrane, wherein materials of the heat-resistant fiber layer contain a first polymeric material and a second polymeric material; the first polymeric material is a heat-resistant polymeric material whose melting point is above 180° C.; and the melting point of the second polymeric material is lower than that of the first polymeric material, and a liquid absorption rate of the second polymeric material in an electrolyte at 25° C. is above 40% and has an error of ±5%; and
a bonding layer formed on an outermost side of at least one side surface of the polymer composite membrane, the bonding layer comprising:
an acrylate crosslinked polymer, a styrene-acrylate crosslinked copolymer and a vinylidene fluoride-hexafluoropropylene copolymer, or
an acrylate crosslinked polymer and a styrene-acrylate crosslinked copolymer, or
an acrylate crosslinked polymer and a vinylidene fluoride-hexafluoropropylene copolymer, and the porosity of the bonding layer is 40% to 65%; and

wherein the glass transition temperature of the acrylate crosslinked polymer is −20° C. to 60° C., the glass transition temperature of the styrene-acrylate crosslinked copolymer is −30° C. to 50° C., and the glass transition temperature of the vinylidene fluoride-hexafluoropropylene copolymer is −65° C. to −40° C.

2. The polymer composite membrane according to claim 1 , wherein a liquid absorption rate of the first polymeric material in an electrolyte at 25° C. is below 5% and has an error of ±5%; and a liquid absorption rate of the second polymeric material in an electrolyte at 25° C. is 40% to 100% and has an error of ±5%.

3. The polymer composite membrane according to claim 1 , wherein the glass transition temperature of the first polymeric material is above 100° C.; and the melting point of the second polymeric material is 100° C. to 150° C.; and optionally, the glass transition temperature of the second polymeric material is below 25° C.

4. The polymer composite membrane according to claim 1 , wherein a weight ratio between the first polymeric material and the second polymeric material in the heat-resistant fiber layer is (0.5 to 10):1.

5. The polymer composite membrane according to claim 1 , wherein
the first polymeric material is selected from one or more of polyetherimide, poly(ether ether ketone), polyether sulfone, polyamide-imide, polyamic acid, and polyvinylpyrrolidone; and
the second polymeric material is selected from one or more of modified polyvinylidene fluoride, polyacrylate, polyphenyl ethylene, and polyethylene oxide.

6. The polymer composite membrane according to claim 5 , wherein the first polymeric material is polyetherimide, and the second polymeric material is polyvinylidene fluoride-hexafluoropropylene.

7. The polymer composite membrane according to claim 1 , wherein the diameter of fiber in the heat-resistant fiber layer is 100 nm to 2000 nm, and the thickness of the heat-resistant fiber layer is 0.5 μm to 30 μm.

8. The polymer composite membrane according to claim 1 , wherein the heat-resistant fiber layer has a porosity of 75% to 93% and a surface density of 0.2 g/m 2 to 15 g/m 2 .

9. The polymer composite membrane according to claim 1 , wherein the porous base membrane is:
a polymer base membrane, which is a polyolefin membrane, or
a ceramic membrane comprising a polymer base membrane and a ceramic layer formed on at least a side surface of the polymer base membrane, wherein the polymer base membrane is a polyolefin membrane,
and the heat-resistant fiber layer is located on a surface on a side of the ceramic membrane on which the ceramic layer is formed.

10. The polymer composite membrane according to claim 9 , wherein the ceramic layer contains ceramic particles and a binder, and a surface density ρ of the ceramic layer at a thickness of 1 μm satisfies 1.8 mg/cm 2 <ρ≤2.7 mg/cm 2 ;
the ceramic particles are selected from one or more of Al 2 O 3 , SiO 2 , BaSO 4 , BaO, TiO 2 , CuO, MgO, Mg(OH) 2 , LiAlO 2 , ZrO 2 , carbon nanotube (CNT), BN, SiC, Si 3 N 4 , WC, B 4 C, AlN, Fe 2 O 3 , BaTiO 3 , MoS 2 , α-V 2 O 5 , PbTiO 3 , TiB 2 , CaSiO 3 , molecular sieve, clay, boehmite, and kaolin, and optionally, an average particle size of the ceramic particles is 200 nm to 800 nm;
the binder is polyacrylate whose glass transition temperature satisfies −40° C. to 0° C.; and
the single-sided thickness of the ceramic layer is 1 μm to 5 μm.

11. The polymer composite membrane according to claim 9 , wherein in the ceramic layer, relative to the ceramic particles of 100 parts by weight, the content of the binder is 2 to 8 parts by weight;
in the ceramic layer, relative to the ceramic particles of 100 parts by weight, a dispersant of 0.3 to 1 part by weight, a thickener of 0.5 to 1.8 parts by weight, and a surface treating agent of 0 to 1.5 parts by weight are further comprised, and the number-average molecular weight of the dispersant is below 50000;
the dispersant is at least one of polyacrylate, aliphatic polyglycol ether, silicates, phosphates, and guar gum;
the thickener is at least one of polyacrylate having a number-average molecular weight of 300000 to 1500000, a polyacrylate copolymer, polyvinylpyrrolidone, a cellulose derivative, and polyacrylamide; and
the surface treating agent is 3-glycidyloxypropyltrimethoxysilane and/or 3-glycidyloxypropyltriethoxysilane.

12. The polymer composite membrane according to claim 1 , wherein
the bonding layer contains the acrylate crosslinked polymer and the styrene-acrylate crosslinked copolymer and does not contain the vinylidene fluoride-hexafluoropropylene copolymer, and a weight ratio of the acrylate crosslinked polymer to the styrene-acrylate crosslinked copolymer is 1:(0.05 to 2); or
the bonding layer contains the acrylate crosslinked polymer and the vinylidene fluoride-hexafluoropropylene copolymer and does not contain the styrene-acrylate crosslinked copolymer, and a weight ratio of the acrylate crosslinked polymer to the vinylidene fluoride-hexafluoropropylene copolymer is 1:(0.3 to 25); or
the bonding layer contains the acrylate crosslinked polymer, the styrene-acrylate crosslinked polymer, and the vinylidene fluoride-hexafluoropropylene copolymer, and a weight ratio between the acrylate crosslinked polymer, the styrene-acrylate crosslinked copolymer and the vinylidene fluoride-hexafluoropropylene copolymer is 1:(0.01 to 2):(0.3 to 5).

13. The polymer composite membrane according to claim 1 , wherein the acrylate crosslinked polymer is:
a mixture of a first acrylate crosslinked polymer and a second acrylate crosslinked polymer and/or a third acrylate crosslinked polymer, or
a second acrylate crosslinked polymer, or
a third acrylate crosslinked polymer;
the first acrylate crosslinked polymer contains a polymethyl methacrylate chain segment of 70 to 80 wt %, a polyethylene acrylate chain segment of 2 to 10 wt %, a polybutyl acrylate chain segment of 10 to 20 wt %, and a polyacrylic acid chain segment of 2 to 10 wt %, the second acrylate crosslinked polymer contains a polymethyl methacrylate chain segment of 30 to 40 wt %, a polyethylene acrylate chain segment of 2 to 10 wt %, a polybutyl acrylate chain segment of 50 to 60 wt %, and a polyacrylic acid chain segment of 2 to 10 wt %, and the third acrylate crosslinked polymer contains a polymethyl methacrylate chain segment of 50 to 80 wt %, a polyethylene acrylate chain segment of 2 to 10 wt %, a polybutyl acrylate chain segment of 15 to 40 wt %, and a polyacrylic acid chain segment of 2 to 10 wt

Assignees

• Byd Co Ltd

Inventors

• Hu Jialing
• Shan Jun
• Wu Jinxiang
• He Long

Classifications

• H01M50/454 Primary

  comprising a non-fibrous layer and a fibrous layer superimposed on one another · CPC title

• H01M50/491

  Porosity · CPC title

• H01M50/434

  Ceramics · CPC title

• H01M50/426

  Fluorocarbon polymers · CPC title

• H01M50/42

  Acrylic resins · CPC title