Solid polymer electrolyte and method of preparation

• US 20030180624A1
• Filed: 03/22/2002
• Published: 09/25/2003
• Est. Priority Date: 03/22/2002
• Status: Abandoned Application

• Current Assignee: Bookeun Oh, Donald R. Vissers, Khalil Amine, Yoo-Eup Hyung
• Original Assignee: Bookeun Oh, Donald R. Vissers, Khalil Amine, Yoo-Eup Hyung
• Inventors: Hyung, Yoo-Eup, Amine, Khalil, Vissers, Donald R., Oh, Bookeun
• Application Number:
  US10/104,352
• Publication Number:
  US 20030180624A1
• Time in Patent Office: Days
• US Class Current: 429/313
• CPC Class Codes: C08L 83/12 containing polyether sequences
• CPC Class Codes: H01B 1/122 Ionic conductors
• CPC Class Codes: H01M 10/0431 Cells with wound or folded electrodes H01M10/045 takes precedence
• CPC Class Codes: H01M 10/052 Li-accumulators
• 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 10/0565 Polymeric materials, e.g. gel-type or solid-type
• CPC Class Codes: H01M 10/0585 of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
• CPC Class Codes: H01M 10/0587 of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
• CPC Class Codes: H01M 10/38 Construction or manufacture
• CPC Class Codes: H01M 2300/0082 Organic polymers
• CPC Class Codes: H01M 6/181 with polymeric electrolytes
• 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 29/49115 including coating or impregnating

Abstract

Disclosed is an improved solid electrolyte made of an interpenetrating network type solid polymer comprised of two compatible phases: a crosslinked polymer for mechanical strength and chemical stability, and an ionic conducting phase. The highly branched siloxane polymer of the present invention has one or more poly(ethylene oxide) (“PEO”) groups as a side chain. The PEO group is directly grafted to silicon atoms in the siloxane polymer. This kind of branched type siloxane polymer is stably anchored in the network structure and provides continuous conducting paths in all directions throughout the IPN solid polymer electrolyte. Also disclosed is a method of making an electrochemical cell incorporating the electrolyte. A cell made accordingly has an extremely high cycle life and electrochemical stability.

Claims

1. In an electrochemical cell, an interpenetrating network solid polymer electrolyte comprising at least one branched siloxane polymer having one or more poly(alkylene oxide) branch as a side chain, at least one crosslinking agent, at least one monofunctional monomeric compound for controlling crosslinking density, at least one metal salt and at least one radical reaction initiator.

2. The interpenetrating network solid polymer electrolyte of claim 1, wherein said poly(alkylene oxide) side chain of siloxane polymer is represented by formulas (I-a and I-b) as a metal ion conducting phase,

3. The interpenetrating network solid polymer electrolyte of claim 1, wherein said crosslinking agent is represented by formula (II),

4. The interpenetrating network solid polymer electrolyte of claim 1, wherein said monomeric unit for controlling crosslinking density is represented by formula (III),

5. The interpenetrating network solid polymer electrolyte of claim 2, wherein the branched siloxane polymer contained therein in a proportion of 10 to 80 percent by weight of total weight of organic compounds in the solid polymer electrolyte.

6. The interpenetrating network solid polymer electrolyte of claim 2, wherein said proportion of said branched siloxane polymer is 30 to 75 percent by weight of total weight of organic compounds in the solid polymer electrolyte.

7. The interpenetrating network solid polymer electrolyte of claim 2, wherein said proportion of said the branched siloxane polymer is 50 to 70 percent by weight of total weight of organic compounds in the solid polymer electrolyte.

8. The interpenetrating network solid polymer electrolyte of claim 3, wherein said crosslinking agent is contained in a proportion of 5 to 60 percent by weight of total weight of organic compounds in the solid polymer electrolyte.

9. The interpenetrating network solid polymer electrolyte of claim 3, wherein said crosslinking agent is contained in a proportion of 10 to 40 percent by weight of total weight of organic compounds in the solid polymer electrolyte.

10. The interpenetrating network solid polymer electrolyte of claim 4, wherein said monomeric compound exists in a proportion of 10 to 50 percent by weight of total weight of organic compounds in the solid polymer electrolyte.

11. The interpenetrating network solid polymer electrolyte of claim 4, wherein said monomeric compound exists in a proportion of 15 to 40 percent by weight of total weight of organic compounds in the solid polymer electrolyte.

12. The interpenetrating network solid polymer electrolyte of claim 1, wherein said at least one metal salt is a lithium salt.

13. An interpenetrating network polymer electrolyte of claim 12, wherein said lithium salt comprises one or more of the following:

LiClO₄, LiBF₄, LiAsF₆, LiPF₆, LiCF₃SO₃, Li(CF₃SO₂)₂N, Li(CF₃SO₂)₃C, LiN(SO₂C₂F₅) ₂, lithium alkyl fluorophosphates and a mixture thereof.

14. The interpenetrating network solid polymer electrolyte of claim 12, wherein molar ratio of said lithium salt relative to the total molar concentration of oxygen in all of the organic compounds in the polymer electrolyte is 0.01 to 0.2.

15. The interpenetrating network solid polymer electrolyte of claim 1, wherein said at least one radical reaction initiator is a thermal initiator.

16. The interpenetrating network polymer electrolyte of claim 15, wherein the thermal initiator is selected from azo compounds, peroxide compounds, bismaleimide and mixtures thereof.

17. The interpenetrating network polymer electrolyte of claim 16, wherein said azo compounds include azoisobutyronitrile.

18. The interpenetrating network polymer electrolyte of claim 16, wherein said peroxide compounds include benzoylperoxide.

19. The interpenetrating network polymer electrolyte of claim 1, wherein said electrolyte is incorporated into a porous medium.

20. The interpenetrating network polymer electrolyte of claim 19, wherein said porous medium is selected from polyolefin separator, polyolefin nonwoven type separator and polycarbonate microporous membrane.

21. A method for preparing the interpenetrating network polymer electrolyte of claim 1, comprising the steps of:

a) dissolving a lithium salt and a radical initiator in a branched siloxane polymer;

mixing at least one crosslinking agent and a monomeric compound with the resulting solution;

b) casting the resulting mixture onto a substrate; and

placing the cast liquid film in an oven or a heating medium such as hot plate for solidification thereof.

22. The method of claim 21 wherein said substrate is a porous medium.

23. The method of claim 21 wherein said substrate is a surface of an electrode.

24. A lithium ion rechargeable cell comprising of at least one lithium metal or lithium alloy anode, the solid polymer electrolyte of claim 1, and at least one metal oxide cathode.

25. A lithium rechargeable cell comprising at least one carbon anode, interpenetrating network solid polymer electrolyte of claim 1, and at least one metal oxide cathode.

28. A method for assembling a lithium rechargeable cell with the solid polymer electrolyte of claim 8, comprising the steps of:

a) stacking each component including a porous supporter, at least one cathode laminate and at least one anode laminate to assemble the cell;

b) winding or folding the stacked components to prepare a spiral wound cell or prismatic cell;

putting the cell in a metal can, plastic pouch or foil-plastic laminated pouch;

injecting the mixture of the electrolyte components listed in claim 1 into the pre-assembled cell; and

c) curing the cell to change the precursor solution to solid polymer electrolyte.

26. A method for assembling a lithium rechargeable cell with the solid polymer electrolyte, comprising the steps of:

a) coating at least one branched siloxane polymer having one or more poly(alkylene oxide) as a side chain, at least one crosslinking agent, at least one monofunctional monomeric compound for controlling crosslinking density, at least one metal salt and at least one radical reaction initiator onto one or more surfaces of a porous supporter, a cathode laminate and anode laminate;

b) curing the precursor solution to make solid polymer electrolyte;

c) stacking each components including porous supporter, cathode laminate and anode laminate;

d) winding or folding the stacked components to prepare spiral wound cell or prismatic cell; and

e) packaging the cell in a metal can, plastic pouch or foil-plastic laminated pouch.

27. A method for assembling a lithium ion rechargeable cell with the solid polymer electrolyte, comprising the steps of:

a) coating at least one branched siloxane polymer having one or more poly(alkylene oxide) as a side chain, at least one crosslinking agent, at least one monofunctional monomeric compound for controlling crosslinking density, at least one metal salt and at least one radical reaction initiator onto one or more surfaces of a porous supporter, a cathode laminate and an anode laminate;

b) stacking each component including said porous supporter, said cathode laminate and said anode laminate;

c) winding or folding the stacked components to prepare spiral wound cell or prismatic cell;

d) curing the cell to change the precursor solution to solid polymer electrolyte; and

packaging the cell with metal can, plastic pouch, or foil-plastic laminated pouch..