Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Patent
1996-03-21
1998-05-12
Maples, John S.
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
429194, 429217, H01M 1040, H01M 402
Patent
active
057502870
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an organic electrolytic cell having a high capacity and high voltage, wherein an infusible, insoluble substrate having a polyacene type skeletal structure is used as the negative electrode, and a metallic oxide is used as the positive electrode.
In recent years, a secondary cell wherein an electrically conductive macromolecule, an oxide of a transition metal or the like is used as the positive electrode, and metallic lithium or a lithium alloy is used as the negative electrode has been proposed as a cell to be used in place of Ni-Cd storage cells and lead storage cells, because of its high energy density.
However, when such a secondary cell is subjected to repeated charge and discharge, its capacity is largely lowered due to deterioration of the positive electrode or negative electrode, and thus there still remains a problem in its practical aspect. Particularly by deterioration of the negative electrode, mossy lithium, called dendrites, are formed, and through repeated charge and discharge, the dendrites finally penetrates the separator and causes a short circuit, and in some case the cell is ruptured, and thus there has been a problem in its safety, too.
Recently, for solving the above problems, there has been proposed a cell wherein a carbonic material, such as graphite, is used as the negative electrode, and a lithium-containing metallic oxide, such as LiCoO.sub.2, is used as the positive electrode. The cell is a so-called rocking chair-type cell wherein after assembly of the cell, lithium is supplied from the lithium-containing metallic oxide as the positive electrode to the negative electrode through charge, and lithium of the negative electrode is returned to the positive electrode through discharge. Although the cell is characterized by a high voltage and high capacity, its capacity is at most on the order of 80 to 90 mAh/cc (based on the total volumes of the electrodes; the separator and the current collectors); the high energy density which is a characteristic of lithium cells has not been obtained.
On the other hand, an infusible, insoluble substrate having a polyacene type skeletal structure and having a hydrogen/carbon atomic ratio of 0.5 to 0.05, which is a heat-treated product of an aromatic condensation polymer, can be doped with a larger amount of lithium, compared with general carbonic materials. However, when a cell was assembled using the infusible, insoluble substrate, its capacity was not adequately satisfactory.
SUMMARY OF THE INVENTION
Thus, the first object of the present invention lies in providing a secondary cell having a high capacity and high voltage.
Another object of the invention lies in providing such a secondary cell that charge and discharge are possible over a long term and is excellent in safety.
Still another object of the invention lies in providing a secondary cell which is easy to prepare.
Still another object of the invention will be apparent from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial sectional view illustrating the structure of a first embodiment of the cell of the invention and
FIG. 2 is a cutout view illustrating the structure of a second embodiment of the cell of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The present inventors found that for attaining the above objects and advantages, it is important to use a metallic oxide as the positive electrode and an infusible, insoluble substrate having a polyacene type skeletal structure as the negative electrode, and control the amount of lithium in the cell appropriately.
More detailedly, it was found that the above objects and advantages can be accomplished by an organic electrolytic cell equipped with a positive electrode, a negative electrode and a solution of a lithium salt in an aprotic organic solvent as an electrolytic solution, wherein polyacene type skeletal structure and a hydrogen/carbon atomic ratio of 0.5 to 0.05, said substrate being a heat-treated product of an aromatic condensati
REFERENCES:
patent: 4601849 (1986-07-01), Yata
patent: 4615960 (1986-10-01), Yata
Ando Nobuo
Anekawa Akihiro
Hashimoto Takeshi
Hato Yukinori
Kinoshita Hajime
Kanebo Ltd.
Maples John S.
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