SILICON-GRAPHENE NANOCOMPOSITES FOR ELECTROCHEMICAL APPLICATIONS

• US 20140255785A1
• Filed: 11/13/2013
• Published: 09/11/2014
• Est. Priority Date: 05/18/2012
• Status: Active Grant

• Current Assignee: NanoXplore Co.
• Original Assignee: XG Sciences, Inc.
• Inventors: WANG, Liya, DO, Inhwan, WANG, Hong, BAMBHANIA, Harshal Manubhai
• Granted Patent: US 10,079,389 B2
• Time in Patent Office: Days
• US Class Current: 429/231.8
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C09D 1/00 Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances
• CPC Class Codes: C09D 7/61 inorganic
• CPC Class Codes: H01B 1/04 mainly consisting of carbon-silicon compounds, carbon or silicon
• CPC Class Codes: H01G 11/36 Nanostructures, e.g. nanofibres, nanotubes or fullerenes
• CPC Class Codes: H01G 11/50 specially adapted for lithium-ion capacitors, e.g. for lithium-doping or for intercalation
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/366 as layered products
• CPC Class Codes: H01M 4/386 Silicon or alloys based on silicon
• CPC Class Codes: H01M 4/625 Carbon or graphite
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A nanographitic composite for use as an anode in a lithium ion battery includes nanoscale particles of an electroactive material; and a plurality of graphene nanoplatelets having a thickness of 0.34 nm to 5 nm and lateral dimensions of less than 900 nm, wherein the electroactive particle has an average particle size that is larger than the average lateral dimension of the graphene nanoplatelets, and the graphene nanoplatelets coat at least a portion of the nanoscale particles to form a porous nanographitic layer made up of overlapping graphene nanoplatelets.

Claims

1. A nanographitic composite for use as an anode in a lithium ion battery, comprising:

particles of an electroactive material; and

a coating layer comprising a plurality of graphene nanoplatelets having a thickness of 0.34 nm to 50 nm and a lateral dimension of less than 900 nm, wherein

the electroactive particles have a lateral dimension that is larger than the lateral dimension of the graphene nanoplatelets, and

the graphene nanoplatelets coat at least a portion of the nanoscale particles to form a layer made up of overlapping graphene nanoplatelets.

2. The nanographitic composite of claim 1, wherein the graphene nanoplatelets-coated nanoscale particles form agglomerates.

3. The nanographitic composite of claim 1, wherein the longest lateral dimension of the graphene nanoplatelets is less than 50% of the lateral dimension of the electroactive particle.

4. The nanographitic composite of claim 1, wherein the longest lateral dimension of the graphene nanoplatelets is less than 25% of the lateral dimension of the electroactive particle.

5. The nanographitic composite of claim 1, wherein longest lateral dimension of the graphene nanoplatelets is less than 10% of the lateral dimension of the electroactive particle.

6. The nanographitic composite of claim 1, wherein more than 50% of the surface area of the electroactive particle is coated by the nanographene coating layer.

7. The nanographitic composite of claim 1, wherein more than 70% of the surface area of the electroactive particle is coated by the nanographene coating layer.

8. The nanographitic composite of claim 1, wherein more than 80% of the surface area of the electroactive particle is coated by the nanographene coating layer.

9. The nanographitic composite of claim 1, wherein more than 90% of the surface area of the electroactive particle is coated by the nanographene coating layer.

10. The nanographitic composite of claim 1, wherein more than 95% of the surface area of the electroactive particle is coated by the nanographene coating layer.

11. The nanographitic composite of claim 1, wherein more than 50% of the electroactive particles have a lateral dimension that is larger than the lateral dimension of the nanographene platelets coating the particles.

12. The nanographitic composite of claim 1, wherein more than 60% of the electroactive particles have a lateral dimension that is larger than the lateral dimension of the nanographene platelets coating the particles.

13. The nanographitic composite of claim 1, wherein more than 70% of the electroactive particles have a lateral dimension that is larger than the lateral dimension of the nanographene platelets coating the particles.

14. The nanographitic composite of claim 1, wherein more than 80% of the electroactive particles have a lateral dimension that is larger than the lateral dimension of the nanographene platelets coating the particles.

15. The nanographitic composite of claim 1, wherein more than 90% of the electroactive particles have a lateral dimension that is larger than the lateral dimension of the nanographene platelets coating the particles.

16. The nanographitic composite of claim 1, wherein more than 95% of the electroactive particles have a lateral dimension that is larger than the lateral dimension of the nanographene platelets coating the particles.

17. The nanographitic composite of claim 1, wherein the graphene nanoplatelets have a lateral dimension of less than 500 nm.

18. The nanographitic composite of claim 1, wherein the graphene nanoplatelets have a lateral dimension of 30 nm to 200 nm.

19. The nanographitic composite of claim 1, wherein the layer comprises multiple layers of graphene nanoplatelets.

20. The nanographitic composite of claim 1, wherein the electroactive material one or more material selected from the group consisting of silicon, tin, iron, magnesium, aluminum, lead, gold, silver, titanium, platinum, palladium, ruthenium, copper, nickel, rhodium and nickel and combinations thereof.

21. The nanographitic composite of claim 1, wherein electroactive material comprises silicon.

22. The nanographitic composite of claim 21 wherein the silicon is present in a range from 5 wt % to 90 wt % of the composite.

23. The nanographitic composite of claim 21, wherein the silicon is present in a range from 40 wt % to 70 wt % of the composite.

24. The nanographitic composite of claim 1, wherein the composite further comprises a conductive carbon additive.

25. The nanographitic composite of claim 24, wherein the conductive carbon additive is selected from the group consisting of carbon black, acetylene black, carbon nanotube, carbon fiber, carbon nanohorn, carbon nanocoil and combinations thereof.

26. The nanographitic composite of claim 1, wherein the composite has a tap density of greater than 0.50 g/cm³.

27. The nanographitic composite of claim 1, wherein the composite has a tap density of greater than 0.8 g/cm³.

28. The nanographitic composite of claim 1, wherein the electroactive particle is present in a range from 5 wt % to 90 wt % of the composite.

29. The nanographitic composite of claim 1, wherein the surface area is in the range of 50 to 200 m²/g.

30. An electrode for use as an anode in a lithium ion battery, said electrode comprising:

(a) the nanographitic composite according to claim 1; and

(b) a binder.

31. The electrode of claim 30, further comprising a conductive additive.

32. The electrode of claim 31, wherein the conductive additive comprises a graphene.

33. The electrode of claim 31, wherein the conductive additive is 2 to 20 wt % of the total electrode weight.

34. The electrode of claim 30, wherein the binder is 3 to 20 wt % of the total electrode weight.

35. A lithium ion battery comprising:

an anode according to claim 30;

a cathode;

a separator spacing apart the anode and the cathode; and

an electrolyte in contact with the anode and the cathode.

36. A method of making a nanocomposite suitable for use in a lithium ion battery, comprising:

introducing an electroactive particle powder into a high energy dry mill, wherein the particles are of a micron-scale dimension;

introducing a graphite particle powder into the high energy dry mill, wherein the particles are of a micron-scale dimension; and

milling the electroactive particle powder and the graphite particle powder, to exfoliate the graphite and reduce the particle size of the electroactive particle to less than 3 um and reduce the particle size of the graphite particle to less than 900 nm;

wherein the exfoliated size-reduced graphite coats the surface of the sized-reduced electroactive particle, and

wherein the resultant nanocomposite has a bulk density of greater than 0.50 g/cm³.

37. An electrode material comprising nanographene platelets and an electroactive material wherein the nanographene platelets are covalently bonded to the electro active material by pi bonds or partial pi bonds.

38. A nanocomposite prepared by:

the reaction of nanographitic platelets having a thickness of 0.34 nm to 50 nm and lateral dimensions of less than 900 nm, with electroactive particles, wherein the electroactive particle has an lateral dimension that is larger than a lateral dimension of the nanographitic platelets.

39. A nanographitic composite for use as an anode in a lithium ion battery, comprising:

a plurality of composite particles comprising;

an electroactive particle;

a coating layer comprising an inner layer of graphene nanoplatelets that are tightly bound to the electroactive particle and an outer layer of graphene nanoplatelets that interact loosely with the inner layer of graphene nanoplatelets, wherein the nanographitic platelets covers at least a portion of the nanoscale particle to form a nanographitic layer.

40. The nanographitic composite of claim 39, wherein the inner layer comprises a mixture of carbon and silicon.

41. The nanographitic composite of claim 39, wherein the inner layer has a thickness in the range of 5-25 nm.

42. The nanographitic composite of claim 39, wherein the inner layer is integral with the electroactive particle.

43. The nanographitic composite of claim 39, wherein the inner layer is crystalline.

44. The nanographitic composite of claim 39, wherein the inner layer is disordered or amorphous.

45. The nanographitic composite of claim 39, wherein the electroactive particle comprises silicon and the inner layer comprises an SiC intermetallic.

46. The nanographitic composite of claim 39, wherein the inner layer is covalently bonded to the electroactive particle.

47. The nanographitic composite of claim 46 wherein the covalent bond is a pi-bond or a partial pi-bond.

48. The nanographitic composite of claim 39 wherein the silicon and carbon content of the inner layer varies across its thickness.

49. The nanographitic composite of claim 39, wherein the graphene nanoplatelets-coated nanoscale particles form agglomerates.

50. The nanographitic composite of claim 39, wherein the graphene nanoplatelets have a thickness of 0.34 nm to 50 nm and lateral dimensions of less than 900 nm.

51. The nanographitic composite of claim 39, wherein the coating layer comprises multiple layers of graphene nanoplatelets.

52. The nanographitic composite of claim 39, wherein the electroactive particle one or more selected from the group consisting of silicon, tin, iron, magnesium, aluminum, lead, gold, silver, titanium, platinum, palladium, ruthenium, copper, nickel, rhodium and nickel and combinations thereof.

53. The nanographitic composite of claim 39, wherein electroactive particle comprises silicon.

54. The nanographitic composite of claim 53, wherein the silicon is present in a range from 10 wt % to 90 wt % of the composite.

55. The nanographitic composite of claim 54, wherein the composite further comprises a conductive carbon additive.

56. The nanographitic composite of claim 55, wherein the conductive carbon additive is selected from the group consisting of carbon black, acetylene black, carbon nanotube, carbon fiber, carbon nanohorn, carbon nanocoil and combinations thereof.

57. The nanographitic composite of claim 39, wherein the composite has a tap density of greater than 0.50 g/cm³.

58. The nanographitic composite of claim 39, wherein the composite has a tap density of greater than 0.8 g/cm³.

59. The nanographitic composite of claim 53, wherein the silicon is present in a range from 10 wt % to 90 wt % of the composite.

60. An electrode for use as an anode in a lithium ion battery, said electrode comprising:

(a) the nanographitic composite according to claim 39; and

(b) a binder.

61. The electrode of claim 60, further comprising a conductive additive.

62. The electrode of claim 61, wherein the conductive additive comprises a graphene.

63. The electrode of claim 61, wherein the conductive additive is 2 to 20 wt % of the total electrode weight.

64. The electrode of claim 60, wherein the binder is 3 to 20 wt % of the total electrode weight.

65. A lithium ion battery comprising:

an anode according to claim 60;

a cathode;

a separator spacing apart the anode and the cathode; and

an electrolyte in contact with the anode and the cathode.