1. A radio frequency identification transponder comprising:
a microstrip patch antenna;
a first feed and a second feed, each feed being coupled with an edge of the microstrip patch antenna, and the first feed being approximately 180 degrees out of phase with the second feed; and
a matching circuit coupling the first and second feeds with an integrated circuit.
2. The radio frequency identification transponder as set forth in claim 1, wherein the first feed and the second feed are each located an approximately equal distance from and on opposite sides of an approximate center of a non-radiating edge.
3. The radio frequency identification transponder as set forth in claim 1, wherein the first feed and the second feeds each consist of one or more microstrip transmission lines.
4. The radio frequency identification transponder as set forth in claim 1, wherein the matching circuit includes a first transmission line coupled with the first feed and a second transmission line coupled with the second feed, with the first and second transmission lines being substantially symmetrical with respect to an approximate center between the first and second feeds.
5. The radio frequency identification transponder as set forth in claim 4, wherein the first transmission line and the second transmission line are coupled with the integrated circuit.
6. The radio frequency identification transponder as set forth in claim 1, wherein the matching circuit consists of a first transmission line coupled with the first feed and a second transmission line coupled with the second feed, with the first and second transmission lines being substantially symmetrical with respect to an approximate center between the first and second feeds.
7. The radio frequency identification transponder as set forth in claim 1, wherein the matching circuit includes a transmission line coupling the first feed with the second feed and creating a virtual short between the feeds.
8. In a radio frequency identification transponder for physical association with an object and for storing and communicating data regarding the object, the radio frequency identification transponder having a microstrip patch antenna and an integrated circuit, the improvement comprising:
a first feed and a second feed, each feed being coupled with an edge of the microstrip patch antenna, and the first feed being approximately 180 degrees out of phase with the second feed; and
a matching circuit coupling the first and second feeds with the integrated circuit, the matching circuit including a transmission line coupling the first feed with the second feed and creating a virtual short between the feeds.
9. The radio frequency identification transponder as set forth in claim 8, wherein the first feed and the second feed are each located an approximately equal distance from and on opposite sides of an approximate center of a non-radiating edge.
10. The radio frequency identification transponder as set forth in claim 8, wherein the first feed and the second feed each consist of one or more microstrip transmission lines.
11. The radio frequency identification transponder as set forth in claim 8, wherein the matching circuit consists of a first transmission line coupled with the first feed and a second transmission line coupled with the second feed, with the first and second transmission lines being substantially symmetrical with respect to an approximate center between the first and second feeds.
12. A radio frequency identification transponder comprising:
a first patch antenna and a second patch antenna;
an integrated circuit having a first pair of terminals and a second pair of terminals; and
a first matching circuit for coupling the first patch antenna to the first pair of terminals, wherein the first matching circuit resonates at a first frequency; and
a second matching circuit for coupling the second patch antenna to the second pair of terminals, wherein the second matching circuit resonates at a second frequency.
13. The radio frequency identification transponder as set forth in claim 12, further including, for each patch antenna, first and second balanced feeds and a shorting stub coupling the balanced feeds.
14. The radio frequency identification transponder as set forth in claim 12, wherein the first patch antenna is a microstrip patch antenna operable above a ground plane separated by a substrate, and the second patch antenna is operable with the substrate in free space.
15. The radio frequency identification transponder as set forth in claim 12, wherein the first frequency is approximately identical to the second frequency.
16. In a radio frequency identification transponder for physical association with an object and for storing and communicating data regarding the object, the improvement comprising:
a first patch antenna and a second patch antenna;
an integrated circuit having a first pair of terminals and a second pair of terminals;
a first matching circuit for coupling the first patch antenna to the first pair of terminals wherein the first matching circuit resonates at a first frequency; and
a second matching circuit for coupling the second patch antenna to the second pair of terminals, wherein the second matching circuit resonates at a second frequency.
17. The radio frequency identification transponder as set forth in claim 16, further including, for each patch antenna, first and second balanced feeds and a shorting stub coupling the balanced feeds.
18. The radio frequency identification transponder as set forth in claim 16, wherein the first patch antenna is a microstrip patch antenna operable above a ground plane separated by a substrate, and the second patch antenna is operable with the substrate in free space.
19. The radio frequency identification transponder as set forth in claim 16, wherein the first frequency is approximately identical to the second frequency.
20. A radio frequency identification transponder comprising:
a microstrip patch antenna having an annular shape with an inner edge and an outer edge;
an integrated circuit;
a first feed and a second feed, each feed being coupled with either edge of the microstrip patch antenna, and the first feed being approximately 180 degrees out of phase with the second feed; and
a matching circuit coupling the first and second feeds with the integrated circuit, the matching circuit including a transmission line coupling the first feed with the second feed and creating a virtual short between the feeds.
21. The radio frequency identification transponder as set forth in claim 20, wherein the matching circuit is coupled with the inner edge of the microstrip patch antenna.
22. The radio frequency identification transponder as set forth in claim 20, wherein the matching circuit is coupled with the outer edge of the microstrip patch antenna.
23. The radio frequency identification transponder as set forth in claim 20, wherein the microstrip patch antenna has an annular polygonal shape.
24. The radio frequency identification transponder as set forth in claim 23, further including one or more slots manufactured into the annular polygonal shape.
25. In a radio frequency identification transponder for physical association with a cylindrical object having a stem and for storing and communicating data regarding the object, the radio frequency identification transponder having a microstrip patch antenna and an integrated circuit, the improvement comprising:
the microstrip patch antenna having an annular shape with an inner edge and an outer edge;
a first feed and a second feed, each feed being coupled with either edge of the microstrip patch antenna, and the first feed being approximately 180 degrees out of phase with the second feed; and
a matching circuit coupling the first and second feeds with the integrated circuit, the matching circuit including a transmission line coupling the first feed with the second feed and creating a virtual short between the feeds,
wherein the matching circuit is coupled with the inner edge of the microstrip patch antenna.
26. The radio frequency identification transponder as set forth in claim 25, wherein the microstrip patch antenna has an annular polygonal shape.
27. The radio frequency identification transponder as set forth in claim 26, further including one or more slots manufactured into the annular polygonal shape.
28. In a radio frequency identification transponder for physical association with a cylindrical object having a stem and for storing and communicating data regarding the object, the radio frequency identification transponder having a microstrip patch antenna and an integrated circuit, the improvement comprising:
the microstrip patch antenna having an annular shape with an inner edge and an outer edge;
a first feed and a second feed, each feed being coupled with either edge of the microstrip patch antenna, and the first feed being approximately 180 degrees out of phase with the second feed; and
a matching circuit coupling the first and second feeds with the integrated circuit, the matching circuit including a transmission line coupling the first feed with the second feed and creating a virtual short between the feeds,
wherein the matching circuit is coupled with the outer edge of the microstrip patch antenna.
29. The radio frequency identification transponder as set forth in claim 28, wherein the microstrip patch antenna has an annular polygonal shape.
30. The radio frequency identification transponder as set forth in claim 29, further including one or more slots manufactured into the annular polygonal shape.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A positive active material, comprising:
a core particle comprising a lithium-containing compound configured to reversibly intercalate and deintercalate lithium; and
a coating material comprising a carbon-fluorine (C\u2014F) bond on a surface of the core particle.
2. The positive active material of claim 1, wherein the coating material comprises a fluorine-bonded carbon nanostructure, a fluorine-bonded graphene, a fluorine-bonded carbon black, a fluorine-bonded graphite, a fluorine-bonded acetylene black, a fluorine-bonded carbon fine powder, a fluorinated organic material, or a combination thereof.
3. The positive active material of claim 2, wherein the fluorine-bonded carbon nanostructure comprises a fluorine-bonded carbon nanotube, a fluorine-bonded carbon nano fiber, a fluorine-bonded carbon nano ribbon, a fluorine-bonded carbon nano bead, or a combination thereof.
4. The positive active material of claim 2, wherein the coating material comprises a fluorine-bonded carbon nanostructure comprising the C\u2014F bond, and the C\u2014F bond of the fluorine-bonded carbon nanostructure exhibits a peak in a range of about 950 cm\u22121 to about 1350 cm\u22121 as measured by FT-IR spectroscopy.
5. The positive active material of claim 1, wherein:
the core particle further comprises carbon; and
the C\u2014F bond of the coating material is formed from at least a portion of the carbon of the core particle, and exhibits a peak in a range of about 1150 cm\u22121 to about 1160 cm\u22121 as measured by FT-IR spectroscopy.
6. The positive active material of claim 1, wherein the core particle further comprises carbon, and the coating material further comprises LiF.
7. The positive active material of claim 6, wherein the LiF exhibits a (111) peak at a 2\u03b8 value of about 39\xb0, a (200) peak at a 2\u03b8 value of about 45\xb0, and a (220) peak at a 2\u03b8 value of about 63\xb0 as measured by X-ray diffraction (XRD) analysis.
8. A method of manufacturing a positive active material, the method comprising:
preparing a lithium-containing compound configured to reversibly intercalate and deintercalate lithium; and
forming a coating layer on a surface of the lithium-containing compound, the coating layer comprising a coating material comprising a carbon-fluorine (C\u2014F) bond.
9. The method of claim 8, wherein the forming the coating layer comprises:
fluorinating the surface of a carbon particle to form a fluorinated carbon particle; and
coating the surface of the lithium-containing compound with the fluorinated carbon particle.
10. The method of claim 9, wherein the carbon particle comprises a carbon nanostructure, graphene, carbon black, graphite, acetylene black, a carbon fine powder, an organic material, or a combination thereof.
11. The method of claim 9, wherein the fluorinating the surface of the carbon particle comprises:
supplying a fluorine-containing gas and an inert gas at a ratio in a range of about 5:95 to about 95:5 (vv) at a temperature in a range of about 25\xb0 C. to about 500\xb0 C. to the carbon particle.
12. The method of claim 8, wherein the forming the coating layer comprises:
forming a carbon thin layer on the lithium-containing compound; and
fluorinating the carbon thin layer.
13. The method of claim 12, wherein the forming the carbon thin layer on the lithium-containing compound comprises:
preparing a mixture of the lithium-containing compound and a carbon precursor to form a mixture; and
heat-treating the mixture.
14. The method of claim 13, wherein the carbon precursor is included in the mixture in an amount in a range of about 0.1 wt % to about 30 wt % based on the total amount of the mixture.
15. The method of claim 12, wherein the fluorinating the carbon thin layer comprises:
supplying a fluorine-containing gas and an inert gas at a ratio in a range of about 5:95 to about 95:5 (vv) to the carbon thin layer at a temperature in a range of about 25\xb0 C. to about 500\xb0 C.
16. The method of claim 8, wherein the forming the coating layer comprises directly fluorinating the surface of the lithium-containing compound.
17. A rechargeable lithium battery, comprising:
a positive electrode comprising the positive active material according to claim 1;
a negative electrode; and
an electrolyte.
18. The rechargeable lithium battery of claim 17, further comprising:
a LiF film formed on the surface of the positive electrode.
19. The rechargeable lithium battery of claim 18, wherein the LiF film exhibits a binding energy peak in a range of about 685 eV to about 690 eV in an X-ray diffraction (XRD) analysis.