Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Reexamination Certificate
1999-07-21
2001-11-13
Brouillette, Gabrielle (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
Reexamination Certificate
active
06316147
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for producing carbonaceous anode material capable of intercalating or deintercalating light metal ions such as lithium ions, to a carbonaceous anode material obtained by the method, and to a non-aqueous electrolyte cell using such material.
2. Prior Art
Compact portable electronic products such as camcorders, personal handyphone systems, laptop computers, etc., have been developed with recent advance in electronic teclinology, and hence, the development of a compact and light-weight secondary battery having high energy density for use as a portable power source is strongly demanded.
Recently, non-aqueous electrolyte cells using light metals such as lithium, sodium, or aluminum as charge carriers are attracting attention and active study is made thereon as batteries which fulfill the above requirements, because they can achieve higher energy density when compared with nickel-cadmium or lead batteries.
However, when a light metal such as metallic lithium is used as it is for the anode of a non-aqueous electrolyte cell, metallic lithium does not always form a uniform precipitate on the surface of the anode during the charging process (i.e., the process of precipitating metallic lithium), but sometimes form a dendritic precipitate. When such dendrites are formed, they gradually grow with repeated recharging as to finally reach the cathode to possibly cause an internal short circuit.
Accordingly, to prevent such light metal dendrites from forming, it is proposed not to use the light metals directly for the anodes, but to use them as dopants in a material capable of being doped and dedoped therewith. Concerning lithium ions, in particular, lithium-ion non-aqueous electrolyte cells equipped with anodes made of carbonaceous materials capable of intercalating or deintercalating lithium ions, such as natural graphite, artificial graphite, or non-graphitizable carbon materials, and being intercalated with carbon dopants, are now practically available. Such non-aqueous electrolyte cells boast superior safety and reliability, because the formation of dendrites is suppressed by incorporating light metals in non-metallic states.
OBJECT AND SUMMARY OF THE INVENTION
The use of a material capable of intercalating or deintercalating light metal ions for the anode greatly improves the safety and the reliability of a non-aqueous electrolyte cell. However, when using a non-graphitizable carbon material, in particular, it is required to achieve a higher level in energy density (i.e., improvement of capacity characteristics) by increasing the charging and discharging current efficiency.
Furthermore, in general, non-aqueous electrolyte cells suffer a decrease in cell capacity with repeated recharging (i.e., degradation of cyclic properties). Particularly, this degradation occurs more likely when highly crystalline graphite material is used, than when a non-graphitizable carbon material is employed. This is another point to be improved.
Accordingly, an object of the present invention is to overcome the aforementioned problems of prior art technology, and to implement a non-aqueous electrolyte cell having superior capacity characteristics and favorable cyclic properties, while yet employing an anode made of a carbonaceous material capable of intercalating or deintercalating light metal ions.
The present inventors have found that an anode material obtained by irradiating a carbonaceous material, which is capable of intercalating or deintercalating light metal ions under a gaseous atmosphere with an electron beam, accelerated in high vacuum, imparts superior capacity characteristics and favorable cyclic properties to a non-aqueous electrolyte cell. The present invention has been accomplished based on those findings.
More specifically, the present invention provides a method for producing a carbonaceous anode material for a non-aqueous electrolyte cell, characterized in that a carbonaceous material, which is capable of intercalating or deintercalating light metal ions, is subjected to electron beam irradiation when an electron beam accelerated in a vacuum is irradiated under a gaseous atmosphere onto the carbonaceous material.
The present invention also provides a carbonaceous anode material for a non-aqueous electrolyte cell produced by the method above. The present invention furthermore provides a non-aqueous electrolyte cell consisting of an anode capable of being doped and dedoped with a light metal ion, a cathode, and a non-aqueous electrolyte, which uses the aforementioned carbonaceous anode material as the anode thereof.
REFERENCES:
patent: 5578399 (1996-11-01), Olsen
Ata Masafumi
Endo Eishi
Gonno Yoshihisa
Imoto Hiroshi
Kihira Toru
Brouillette Gabrielle
Dove Tracy
Sonnenschein Nath & Rosenthal
Sony Corporation
LandOfFree
Method for producing anode material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing anode material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing anode material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2591356