Solid polymer electrolyte and method of preparation

• US 7,226,702 B2
• Filed: 01/22/2003
• Issued: 06/05/2007
• Est. Priority Date: 03/22/2002
• Status: Expired due to Term

• Current Assignee: Quallion, LLC (EnerSys)
• Original Assignee: Quallion, LLC (EnerSys)
• Inventors: Amine, Khalil, Vissers, Donald R., Oh, Bookeun
• Primary Examiner(s): Dove; Tracy
• Assistant Examiner(s): CONLEY, OI K
• Application Number:
  US10/496,230
• Publication Number:
  US 20050019667A1
• Time in Patent Office: 1,595 Days
• Field of Search: 429/188, 429/189, 429/304, 429/313, 429/317
• US Class Current: 429/304
• 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 29/49108 Electric battery cell making
• 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. An electrochemical device, comprising:

an electrolyte including

at least siloxane polymer including side chains linked to a backbone, at least one silicon in the backbone is linked to one of the side chains as represented in formula I-a

2. The electrochemical device of claim 1, wherein at least one siloxane polymer is non-covalently bonded to the second polymer.

3. The electrochemical device of claim 1, wherein the at least one siloxane polymer is not cross-linked.

4. The electrochemical device of claim 1, wherein the second polymer is cross-linked.

5. The electrochemical device of claim 1, wherein the second polymer has at least one side chain including a poly(alkylene oxide) moiety.

6. The electrochemical device of claim 1, wherein the electrolyte is a solid.

7. The electrochemical device of claim 1, wherein the second polymer is selected so as to be fabricated from a monomer represented by formula (II),

8. The electrochemical device of claim 1, wherein the siloxane polymer is represented by formula I-a

9. The electrochemical device of claim 1, wherein the proportion of the siloxane polymer is 10 to 80 weight percent of the total weight of the polymer in the electrolyte.

10. The electrochemical device of claim 1, wherein the proportion of the siloxane polymer is 50 to 70 weight percent of the total weight of the polymer in the electrolyte.

11. The electrochemical device of claim 1, wherein the second polymer is 5 to 60 weight percent of the total weight of the polymer in the electrolyte.

12. The electrochemical device of claim 1, wherein the second polymer is 10 to 40 weight percent of the total weight of the polymer in the electrolyte.

13. The electrochemical device of claim 1, wherein the electrolyte is incorporated into a porous medium.

14. The electrochemical device of claim 13, wherein the porous medium includes one or more components selected from the group consisting of:

a polyolefin separator, a polyolefin nonwoven type separator, and a polycarbonate microporous membrane.

15. The electrochemical device of claim 1, wherein the electrolyte further comprises:

at least one monofunctional monomeric compound for controlling cross-linking density, and

at least one initiator.

16. The electrochemical device claim 15, wherein the monomeric unit for controlling cross-linking density is represented by formula (III),

17. The electrochemical device claim 15 wherein the monomeric compound is 10 to 50 weight percent of the total weight of the polymer in the electrolyte.

18. The electrochemical device of claim 1, wherein at least one metal salt is a lithium salt.

19. The electrochemical device of claim 18, wherein the lithium salt includes one or more components selected from the group consisting of LiClO₄, LiBF₄, LiAsF₆, LiPF₆, LiCF₃SO₃, Li(CF₃SO₂)₂N, Li(CF₃SO₂)₃C, LiBOB, LiN(SO₂C₂F₅)₂, and lithium alkyl fluorophosphates.

20. The electrochemical device of claim 18, wherein the lithium salt includes LiBOB.

21. The electrochemical device of claim 18, wherein a molar ratio of the lithium salt relative to the molar concentration of oxygen in the solid polymer electrolyte is in a range of 0.01 to 0.2.

22. The electrochemical device of claim 15, wherein the initiator is a thermal initiator.

23. The electrochemical device of claim 15, wherein the initiator includes one or more components selected from a group consisting:

of azo compounds, peroxide compounds, and bismaleimide.

24. The electrochemical device of claim 15, wherein the initiator includes azoisobutyronitrile.

25. The electrochemical device of claim 15, wherein the initiator includes benzoylperoxide.

26. The electrochemical device of claim 15, wherein the second polymer includes a polyalkyldiacrylate.

27. The electrochemical device of claim 15, wherein the second polymer includes a polyalkyldimethacrylate.

28. The electrochemical device of claim 15, wherein the second polymer is one of a plurality of second polymers.

49. The device of claim 8, wherein the second polymer is selected so as to be fabricated from a monomer represented by formula (II),

50. The device claim 49, wherein the second polymer is selected so as to be fabricated from the monomer represented by formula (II) and a co-monomer represented by formula (III),

29. A method of forming an electrochemical device, comprising:

obtaining an electrolyte including

at least one siloxane polymer including side chains linked to a backbone, at least one silicon in the backbone is linked to one of the side chains as represented in formula I-a

30. The method of claim 29, wherein obtaining the electrolyte includes mixing at least one siloxane polymer with a second polymer precursor such that the second polymer precursor forms a second polymer that forms an interpenetrating polymer network with the at least one siloxane polymer.

31. The method of claim 30, wherein mixing at least one siloxane polymer with a second polymer precursor includes mixing at least one compound for terminating polymerization of the second polymer, at least one metal salt, and at least one initiator.

32. The method of claim 29, wherein the interpenetrating network is formed such that at least one siloxane polymer is not covalently bonded to the second polymer.

33. The method of claim 29, wherein the interpenetrating network is formed such that at least one siloxane polymer is not cross-linked.

34. The method of claim 29, wherein the interpenetrating network is formed such that the second polymer is cross-linked.

35. The method of claim 29, wherein obtaining the electrolyte includes forming a second polymer having one or more sides chains that include a poly(alkylene oxide)moiety.

36. The method of claim 29, wherein the electrolyte is a solid.

37. The method of claim 29, wherein obtaining the electrolyte includes forming the second polymer from a monomer represented by formula (II),

38. The method of claim 29, wherein at least siloxane polymer is represented by formula I-a

39. The method of claim 29, wherein the proportion of the siloxane polymer is 10 to 80 percent by weight of the total weight of the solid polymer electrolyte.

40. The method of claim 29, wherein the proportion of the siloxane polymer is 50 to 70 percent by weight of the total weight of the solid polymer electrolyte.

41. The method of claim 29, wherein the second polymer is 10 to 40 percent by weight of the total weight of solid polymer electrolyte.

42. The method of claim 29, further comprising:

incorporating the electrolyte into a porous medium before activating the anode and the cathode.

43. The method of claim 42, wherein the porous medium includes one or more components selected from the group consisting of:

a polyolefin separator, a polyolefin nonwoven type separator, and a polycarbonate microporous membrane.

44. The method of claim 29, wherein obtaining the electrolyte includes forming a polyalkyldiacrylate to serve as the second polymer.

45. The method of claim 29, wherein obtaining the electrolyte includes forming a polyalkyldimethacrylate to serve as the second polymer.

46. The method of claim 29, wherein at least one metal salt is a lithium salt.

47. The method of claim 46, wherein the lithium salt includes one or more components selected from the group consisting of LiClO₄, LiBF₄, LiAsF₆, LiPF₆, LiCF₃SO₃, Li(CF₃SO₂)₂N, Li(CF₃SO₂)₃C, LiN(SO₂C₂F₅)₂, LiBOB, and lithium alkyl fluorophosphates.

48. The method of claim 46, wherein the lithium salt includes LiBOB.