Adhesive-bonded microporous multilayer film

Abstract

Disclosed herein is a multilayer microporous polyolefin film in which at least one layer is highly packed with inorganic particles such that the film exhibits good in-plane dimensional stability (i.e., low shrinkage) at temperatures both above and below the melting point of the polymer matrix. The second extruded polyolefin layer is selected such that the porosity and overall permeability of the multilayer film do not decrease above the melting point of the polymer matrix. The layers of the multilayer film are adhesively bonded, and such a film can be used as a separator to improve the manufacturability, performance, and safety of energy storage devices such as lithium-ion batteries.

Claims

1. A first layer comprising inorganic particles and a polymer matrix containing ultra-high molecular weight polyethylene (UHMWPE), extremely high molecular weight polyethylene (EHMWPE), or a combination thereof, A second layer comprising a polymer matrix containing very high molecular weight polyethylene (VHMWPE), extremely high molecular weight polyethylene (EHMWPE), or a combination thereof, and Includes, The first and second layers are adhesively bonded together, limiting the in-plane shrinkage of the multilayer self-supporting, microporous polyolefin film, while the through-plane permeability decreases above the melting point of either the first or second layer's polymer matrix. A multi-layered, self-supporting, microporous polyolefin film.

2. The first layer comprises at least 65% by weight of inorganic particles, the multilayer self-supporting, microporous polyolefin film according to claim 1.

3. The first layer comprises more than 80% by weight of inorganic particles, as described in claim 1, a multilayer, self-supporting, microporous polyolefin film.

4. The first layer comprises 90% by weight or more inorganic particles, as described in claim 1, a multilayer, self-supporting, microporous polyolefin film.

5. A multilayer, self-supporting, microporous polyolefin film according to any one of claims 1 to 4, further comprising a third layer comprising inorganic particles and a polymer matrix comprising ultra-high molecular weight polyethylene (UHMWPE), extremely high molecular weight polyethylene (EHMWPE), or a combination thereof, wherein the second layer is sandwiched between the first layer and the third layer, and the second layer is adhesively bonded to the first layer and the third layer at adjacent bonding portions.

6. A multilayer, self-supporting, microporous polyolefin film according to any one of claims 1 to 5, wherein the first layer and the second layer are adhesively bonded together without a binder or adhesive.

7. The polyethylene chains of the first and second layers are entangled at the joints between the layers, as described in any one of claims 1 to 6, for a multilayer, self-supporting, microporous polyolefin film.

8. A multilayer, self-supporting, microporous polyolefin film according to any one of claims 1 to 7, further comprising a porous adhesive layer applied to the first layer.

9. The porous adhesive layer comprises polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) copolymer, PVDF-acrylic acid copolymer, acrylate, polyacrylate copolymer, polymethyl methacrylate copolymer, or a mixture thereof, as described in claim 8, a multilayer self-supporting, microporous polyolefin film.

10. A multilayer, self-supporting, microporous polyolefin film according to any one of claims 5 to 9, further comprising a porous adhesive layer applied to the third layer.

11. The first layer and the second layer are laminated together, a multilayer self-supporting, microporous polyolefin film according to any one of claims 1 to 10.

12. The first and second layers are co-extruded to form a monolithic sheet, a multilayer, self-supporting, microporous polyolefin film according to any one of claims 1 to 10.

13. A multilayer, self-supporting, microporous polyolefin film according to any one of claims 1 to 12, having a thickness of approximately 3 μm to approximately 25 μm.

14. A multilayer, self-supporting, microporous polyolefin film according to any one of claims 1 to 13, comprising pores having an average pore diameter of less than approximately 1 micrometer.

15. The inorganic particles comprise an inorganic oxide, carbonate, hydroxide, fluoride, or a mixture thereof, as described in any one of claims 1 to 14, for a multilayer, self-supporting, microporous polyolefin film.

16. The VHMWPE is a multilayer, self-supporting, microporous polyolefin film according to any one of claims 1 to 15, comprising a molecular weight of approximately 500,000 g / mol to approximately 1,000,000 g / mol.

17. The EHMWPE is a multilayer, self-supporting, microporous polyolefin film according to any one of claims 1 to 16, wherein the EHMWPE has a molecular weight of approximately 1 million g / mol to approximately 3.1 million g / mol.

18. The UHMWPE is a multilayer, self-supporting, microporous polyolefin film according to any one of claims 1 to 17, wherein the UHMWPE has a molecular weight of approximately 3.1 million g / mol to approximately 10 million g / mol.

19. An energy storage device comprising a multilayer, self-supporting, microporous polyolefin film according to any one of claims 1 to 18.

20. Forming a first layer comprising inorganic particles and a polymer matrix containing ultra-high molecular weight polyethylene (UHMWPE), extremely high molecular weight polyethylene (EHMWPE), or a combination thereof; Forming a second layer comprising a polymer matrix containing very high molecular weight polyethylene (VHMWPE), extremely high molecular weight polyethylene (EHMWPE), or a combination thereof, The first layer and the second layer are bonded together using adhesive without the use of a bonding agent or adhesive. Includes, A method for producing a multilayer, self-supporting, microporous polyolefin film, wherein the in-plane shrinkage of the multilayer, self-supporting, microporous polyolefin film is limited, while the through-plane permeability decreases above the melting point of the polymer matrix of either the first or second layer.

21. The method according to claim 20, wherein the joint adhesive bonding of the first layer and the second layer comprises co-extruding the first layer and the second layer to form a monolithic sheet.

22. The method according to claim 20, wherein the joint adhesive bonding of the first layer and the second layer comprises laminating the first layer and the second layer.

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