Heat resisting ultrafine fibrous separator and secondary battery using the same

• US 8,815,432 B2
• Filed: 12/08/2006
• Issued: 08/26/2014
• Est. Priority Date: 08/07/2006
• Status: Active Grant

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Jo, Seong-Mu, Kim, Dong-Young, Chin, Byung-Doo
• Primary Examiner(s): Mruk, Brian P
• Application Number:
  US12/376,511
• Publication Number:
  US 20100233523A1
• Time in Patent Office: 2,818 Days
• Field of Search: 429/129, 429/144, 156/167, 428/220, 428/221, 428/304.4, 428/327, 428/338, 428/340, 442/327, 442/400
• US Class Current: 429/129
• CPC Class Codes: B32B 27/02 in the form of fibres or filaments not used
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/12 next to a fibrous or filamentary layer
• CPC Class Codes: B32B 27/30 comprising vinyl (co)polymers; comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/34 comprising polyamides
• CPC Class Codes: B32B 5/26 another layer next to it also being fibrous or filamentary relative arrangement of fibres or filaments of different layers B32B5/12
• CPC Class Codes: D01D 5/0015 characterised by the initial state of the material
• CPC Class Codes: D01F 6/12 from polymers of fluorinated hydrocarbons
• CPC Class Codes: D01F 6/605 from aromatic polyamides
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 50/414 Synthetic resins, e.g. thermoplastics or thermosetting resins
• CPC Class Codes: H01M 50/417 Polyolefins
• CPC Class Codes: H01M 50/44 Fibrous material
• CPC Class Codes: H01M 50/489 Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
• CPC Class Codes: H01M 50/491 Porosity
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 428/249921 Web or sheet containing structurally defined element or component
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]
• CPC Class Codes: Y10T 428/254 : Polymeric or resinous material
• CPC Class Codes: Y10T 428/268 : Monolayer with structurally defined element
• CPC Class Codes: Y10T 428/27 : Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.]
• CPC Class Codes: Y10T 442/60 : Nonwoven fabric [i.e., nonwoven strand or fiber material]
• CPC Class Codes: Y10T 442/68 : Melt-blown nonwoven fabric

Abstract

A heat-resisting ultrafine fibrous separator of the present invention is prepared by an electrospinning process, formed of ultrafine fibers of heat-resisting polymer resin having a melting point more than 1800 C or not having the melting point, or ultrafine fibers of polymer resin capable of swelling in an electrolyte, together with the ultrafine fibers of heat-resisting polymer resin. Also, polyolefine fine particles providing a shutdown function are dispersed in the heat-resisting resin or the polymer resin capable of swelling in the electrolyte. The heat-resisting ultrafine fibrous separator of the present invention has the shutdown function, low thermal contraction, thermal endurance, excellent ionic conductivity and excellent adhesive property with an electrode, so a battery having excellent cycling characteristics, and having high-energy density and high capacity can be prepared.

Claims

1. A heat-resistant, ultrafine fibrous separator configured for use as a separator in an electrochemical battery or a capacitor, comprising:

a first fibrous phase comprising fibers that comprise a first polymeric material having a melting point of more than 180°

C. or not having a melting point; and

a second fibrous phase comprising a second polymeric material that is free of electrolyte, said second polymeric material swelling in electrolyte.

2. The heat-resistant, ultrafine fibrous separator of claim 1, wherein the first polymeric material comprises at least one of aromatic polyester, polyamide, polyimide, polyamidimide, poly(meta-phenylene isophthalamide), polysulfone, polyether ketone, polyether imide, polyphosphazene group, polytetrafluoroethylene, polyurethane copolymer, cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, and combinations thereof.

3. The heat-resistant, ultrafine fibrous separator of claim 1, wherein the content of the fibrous phase of the second polymeric material is 1-95 wt % with respect to the polymer components of the separator.

4. The heat-resistant, fibrous separator of claim 1, wherein the second polymeric material comprises at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-hexafluoropropylene), perfluoropolymer, polyvinylchloride or polyvinylidene chloride and copolymer thereof, polyethylene glycol derivatives, poly-oxide, polyvinyl acetate, poly(vinylpyrrolidone-vinyl acetate), polystyrene, polystyrene acrylonitrile copolymer, polyacrylonitrile copolymer, polymethylmethacrylate, polymethylmethacrylate copolymer, and combinations thereof.

5. The heat-resistant, ultrafine fibrous separator of claim 1, wherein the separator further comprises polyolefine-based fine particles.

6. The heat-resistant, ultrafine fibrous separator of claim 5, wherein a melting point of the fine particles is in the range of 100-180°

C.

7. The heat-resistant, ultrafine fibrous separator of claim 5, wherein the size of the fine particles is in the range of 05-5 μ

m.

8. The heat-resistant, ultrafine fibrous separator of claim 5, wherein the content of the fine particles is in the range of 1-50 g/m² with respect to the separator.

9. The heat-resistant, ultrafine fibrous separator of claim 1, wherein an average diameter of the fibers forming the fibrous phases forming the separator is in the range of 1-3000 nm.

10. The heat-resistant, ultrafine fibrous separator of claim 1, wherein the porosity of the separator is in the range of 30-80%.

11. The heat-resistant, ultrafine fibrous separator of claim 1, wherein the thickness of the separator is in the range of 5-200 μ

m.

12. The heat-resistant, ultrafine fibrous separator of claim 1, wherein the separator further comprises inorganic additives selected from TiO₂, BaTiO₃, Li₂O, LiF, LiOH, Li₃N, BaO, N₂O, Li₂CO₃, CaCO₃, LiAlO₂, SiO₂, Al₂O₃, and combinations thereof.

13. A secondary battery, comprising:

two different electrodes;

a separator inserted between the two electrodes;

said separator being a heat-resistant, ultrafine fibrous separator of claim 1; and

an electrolyte.

14. The secondary battery of claim 13, wherein the separator is coupled to at least one electrode of the two electrodes.

19. The heat-resistant, ultrafine fibrous separator of claim 2, wherein the aromatic polyester comprises at least one of polyethylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, and combinations thereof.

20. The heat-resistant, ultrafine fibrous separator of claim 2, wherein the polyphosphazene group comprises at least one of poly diphenoxy phosphazene, poly{bis[2-(2-methoxyethoxy)phosphazene]}, and combinations thereof.

21. The heat-resistant, ultrafine fibrous separator of claim 2, wherein the polyurethane copolymer comprises at least one of polyurethane and polyetherurethane.

22. The heat-resistant, ultrafine fibrous separator of claim 4, wherein the polyethylene glycol derivatives comprises at least one of polyethylene glycol dialkylene ether and polyethylene glycol dialkylene ester.

23. The heat-resistant, ultrafine fibrous separator of claim 4, wherein the polyoxide comprises at least one of poly(oxymethylene-oligo-oxyethylene), poly(ethylene oxide), and polypropylene oxide.

24. The heat-resistant, ultrafine fibrous separator of claim 4, wherein the polyacrylonitrile copolymer comprises at least one of polyacrylonitrile and polyacrylonitrile methylmethacrylate copolymer.

25. The heat-resistant, ultrafine fibrous separator of claim 1, wherein said first and second fibrous phases are formed by electrospinning fibers from a solution of polymeric material that is free of electrolyte.

26. The heat resistant ultrafine fibrous separator of claim 5 in which the particles are present in the second fibrous phase.

15. A method for fabricating a heat-resistant, ultrafine fibrous separator, comprising:

electrospinning a mixing solution containing a first heat-resistant, polymeric material having a melting point of more than 180°

C. or not having a melting point to form a first fibrous phase and electrospinning a second polymeric material that is swellable when contacted with electrolyte to form a second fibrous phase, said first and second fibrous phases forming a ultrafine fiber web;

wherein said second polymeric material is electrospun in the absence of electrolyte; and

thermally laminating the ultrafine fiber web by pressurization.

17. The method of claim 15, wherein hot-drawing of the ultrafine fiber web is processed before or after the thermally laminating by pressurization thereof.

27. A heat-resistant, ultrafine fibrous separator made by the method of claim 15.

16. A method for fabricating a heat-resistant, ultrafine fibrous separator, comprising:

electrospinning separately a solution containing a heat-resistant polymeric material having a melting point of more than 180°

C. or not having a melting point and a solution containing polymeric material that is swellable when contacted with electrolyte to form a ultrafine fiber web composed of a heat-resisting polymeric ultrafine fiber including a heat-resistant polymeric ultrafine fibrous phase and an ultrafine fiber fibrous phase comprising polymeric material that is swellable when contacted with electrolyte;

wherein said swellable polymeric material is electrospun in the absence of electrolyte; and

thermally laminating the ultrafine fiber web by pressurization.

18. The method of claim 16, wherein hot-drawing of the ultrafine fiber web is processed before or after the thermally laminating by pressurization thereof.

28. A heat-resistant, ultrafine fibrous separator made by the method of claim 16.