Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Reexamination Certificate
2002-02-27
2004-05-25
Chaney, Carol (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
C429S231100, C429S232000
Reexamination Certificate
active
06740453
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to non-aqueous secondary lithium-ion electrochemical cells and batteries.
BACKGROUND
Lithium-ion batteries are considered to be the rechargeable batteries of the future for portable electronics to aerospace to vehicular applications. In a known construction for a lithium-ion battery, carbon or graphite is used as an anode, a lithiated transition metal intercalation compound is used as a cathode and LiPF
6
is used as an electrolyte in carbonate-based nonaqueous solvents.
The electrochemical process is the uptake of lithium ions at the anode during charge and their release during discharge, rather than lithium plating and stripping as occurs in metallic lithium rechargeable battery systems. As metallic lithium is not present in the cell, lithium-ion cells have enhanced safety and a longer cycle life than the cells containing metallic lithium.
At present, disordered carbon (hard carbon) and ordered carbon (graphite) are used as anodes in commercial lithium-ion batteries. The carbonaceous materials can deliver a reversible specific capacity of 372 mAh/g, corresponding to the chemical formula LiC
6
as compared to 3830 mAh/g for metallic lithium. The practical reversible capacity of these carbonaceous materials is even lower in the range of 300-340 mAh/g.
Other carbonaceous materials, also of disordered structure and are known as “soft carbon”, of high reversible capacity have been prepared by pyrolysis of suitable starting materials. Sato et al (Science, 264, 556, 1994) disclosed a carbonaceous material prepared by heating polyparaphenylene at 700° C. which has a reversible capacity of 680 mAh/g. Mabuchi et al (Seventh International Meeting on Lithium Batteries, Extended Abstracts, Page 212, Boston, Mass., 1994) disclosed a low density carbonaceous material prepared by heating coal tar pitch at 700° C. which has a reversible capacity of about 750 mAh/g. Yamada et al (U.S. Pat. No. 5,834,138, Nov. 10, 1998) disclosed a carbonaceous material prepared by heat treatment of coffee beans, tea leaves, corns, etc. at 1100-1200° C. The carbonaceous material delivers a reversible capacity of 500 mAh/g.
These values of reversible capacities are much greater than that of the carbonaceous materials used in commercial lithium-ion cells. However, low density and very high irreversible capacity loss of the above carbonaceous materials limit their commercial use as anodes for lithium-ion batteries.
It has been suggested that the reversible capacity of anodes formed of carbonaceous materials can be increased by the addition of other elements to the carbonaceous materials. For example, the addition of small amounts of phosphorous (European Patent Application No. EP 486950) and boron (Japanese Application Laid-Open No. 03-245458) are alleged to enhance the specific capacity of a carbonaceous anode. Moreover, Canadian Application Serial No. 2,098,248 discloses that substituting electron acceptors (such as boron, aluminum, etc.) for carbon atoms in the structure of the carbonaceous materials will enhance anode capacity.
SUMMARY OF THE INVENTION
The present invention provides a new and different concept for enhancing the reversible capacity of the carbonaceous material forming the active material of an anode in a lithium ion cell or battery. Specifically, the present invention provides a lithium-ion cell in which molybdenum carbide is combined with the carbonaceous material of the anode to enhance the reversible capacity of the carbonaceous material. This concept is also believed to promote the development of high specific energy and energy density lithium-ion cells and batteries.
Accordingly, it is the principal objective of the present invention to improve the reversible capacity of carbonaceous material forming the active material of an anode of a lithium-ion cell or battery.
Another objective of the present invention is to provide a novel and improved rechargeable lithium-ion cell and/or battery having high specific energy and energy density.
Further features of the present invention will become apparent from the following detailed description and the accompanying drawings.
REFERENCES:
patent: 5385794 (1995-01-01), Yokoyama et al.
patent: 5686203 (1997-11-01), Idota et al.
patent: 5834138 (1998-11-01), Yamada et al.
patent: 5939224 (1999-08-01), Bito et al.
patent: 6355377 (2002-03-01), Sheem et al.
patent: 6479426 (2002-11-01), Ryu et al.
patent: 2002/0012845 (2002-01-01), Choi et al.
patent: 2003/0102099 (2003-06-01), Yadav et al.
patent: 2098248 (1994-12-01), None
patent: 0 486 950 (1994-10-01), None
patent: 03-245458 (1991-01-01), None
patent: 10 112316 (1998-04-01), None
patent: 3986 10/112316 (1998-04-01), None
PCT International Search Report, PCT/US03/06080, International filing date Feb. 26, 2003, Priority date Feb. 27, 2002, 3 pages.
Sato et al., “A Mechanism of Lithium Storage in Disordered Carbons,” Science, vol. 264, pp. 556-558, Apr. 22, 1994.
Mabuchi et al., “Charge-Discharge Characteristics of the Mesocarbon Microbeads Heat-Treated at Different Temperatures,” Seventh International Meeting on Lithium Batteries, Extended Abstract, pp. 212-216, 1994.
Braithwaite et al., “Molybdenum: An Outline of its Chemistry and Uses,” pp. 73-75, 1994, Elsevier Science B.V., Amsterdam, The Netherlands.
Hossain Sohrab
Khan Mohamed H.
Chaney Carol
Cyprus Amax Minerals Company
Dahl Bruce E.
Dahl & Osterloth LLP
LandOfFree
Electrochemical cell with carbonaceous material and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electrochemical cell with carbonaceous material and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrochemical cell with carbonaceous material and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3224786