Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and...
Patent
1992-11-02
1994-03-15
Gorgos, Kathryn
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
429194, 429218, 252502, 432 13, H01M 614
Patent
active
052944980
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to an anode material mainly consisting of carbon, phosphorus and oxygen, and to which lithium is doped and undoped, and a method for producing such material. More particularly, it relates to a non-aqueous electrolyte cell having such material as an anode.
BACKGROUND ART
The electrical capacity of a carbonaceous material per unit weight is governed by lithium dosage, and hence it is desirable that lithium dosage of the carbonaceous material be as large as possible in order to increase the charging/discharging capacity of the cell. (Theoretically, one Li atom per six carbon atoms represents an upper limit.)
Up to now, a carbonaceous material obtained by carbonizing an organic material, as described in JP Patent KOKAI Publication No. 62-122066 (1986) or JP Patent KOKAI Publication No. 62-90863 (1987), has been known as the carbonaceous material employed for the anode for this type of the cell.
However, with the above described carbonaceous material, lithium dosage is insufficient and is of the order of about one half of the theoretical value.
The present invention has been proposed for further improving the carbonaceous material. It is an object of the present invention to provide an anode material having lithium dosage far exceeding that of the conventional carbonaceous material, and a method for producing such anode material.
It is another object of the present invention to provide a non-aqueous electrolyte dell having a large discharge capacity and superior in cycle life.
DISCLOSURE OF THE INVENTION
As a result of our eager searches towards achieving the above objects, the present inventors have found that specific compounds containing carbon, phosphorus and oxygen exhibit desirable characteristics as an anode material. Our structural analyses by .sup.31 P solid (Nuclear Magnetic Resonance) and XPS (X-ray photoelectron spectroscopy) have revealed that the added phosphorus atoms do not exist as atoms alone or as compounds, such as oxides, alone, but are reacted with oxygen in the course of sintering to generate a compound having carbon-phosphorus or carbon-oxygen-phosphorus bonds. This means that the effect of addition of the phosphorus compounds, producing an increase in lithium dosage, is not displayed simply as lithium doping and undoping with respect to the carbonaceous material, but is displayed by using a special compound mainly consisting of carbon, oxygen and phosphorus, referred to hereinafter as a C--P--O compound.
The anode material of the present invention has been completed on the basis of the above information. It is mainly composed of a compound consisting essentially of carbon, phosphorus and oxygen with a phosphorus content in an amount of 0.2 to 9.0 wt % and exhibits a peak in a .sup.31 P solid NMR spectrum in a range of .+-.100 ppm based on orthophosphoric acid, while exhibiting a peak in a 2p orbital spectrum of a phosphorus atom of not more than 135 eV in X-ray photoelectron spectroscopy for a carbon-carbon linkage energy in the 1s orbital spectrum of a carbon atom of 284.6 eV.
The method for producing an anode material according to the present invention comprises adding a phosphorus compound to an organic material or a carbonic material in an amount of 0.2 to 32 wt % in terms of phosphorus and sintering the resulting mixture in an inert atmosphere.
A non-aqueous liquid electrolyte cell of the present invention is composed of an anode mainly composed of a compound consisting essentially of carbon, phosphorus and oxygen with a phosphorus content in an amount of 0.2 to 9.0 wt % and exhibits a peak in a .sup.31 P solid NMR spectrum in a range of .+-.100 ppm based on orthophosphoric acid, while exhibiting a peak in a 2p orbital spectrum of a phosphorus atom of not more than 135 eV in X-ray photoelectron spectroscopy for a carbon-carbon linkage energy in the 1s orbital spectrum of a carbon atom of 284.6 eV, an Li-containing cathode and a non-aqueous liquid electrolyte.
By adding a phosphorus compound to the organic material or carbonic material a
REFERENCES:
patent: 5093216 (1992-03-01), Azuma et al.
Azuma Hideo
Nishi Yoshio
Omaru Atsuo
Gorgos Kathryn
Sony Corporation
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