Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Flat-type unit cell and specific unit cell components
Patent
1995-05-24
1997-08-12
Kalafut, Stephen
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Flat-type unit cell and specific unit cell components
429245, 296235, H01M 466
Patent
active
056563914
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an electrochemical alkali metal cell, in particular for rechargeable alkali metal storage batteries. In alkali metal cells alkali metal ions form the species carrying the current, both electrodes and the electrolyte as electrochemically active substance containing the alkali metal A.
Furthermore, the invention is based on a process for manufacture of such an electrochemical cell and a process for manufacture of a separator layer on an electrode for such an electrochemical cell.
Electrodes for electrochemical cells must meet high requirements. In particular a high current density should be made possible by high mobility of the species formed in the electrode reaction. A particular problem results from the fact that the insertion of the species formed leads to changes in volume and that the electrode structure should ensure that a long life and a high number of charging and discharging cycles can be achieved despite these changes in volume. This problem arises in particular with regard to the positive electrode. The ability of the electrode to store as much alkali metal ions as possible and release it again reversibly is determinative for the capacity of a storage battery cell.
One approach to a solution of this problem, on which the main feature of the present invention is also based, is described in EP-A-0017400. An intercalated compound with the general formula A.sub.x M.sub.y O.sub.z is described as the active mass of the positive electrode. It is used in conjunction with a negative electrode, the active substance of which is the alkali metal A. A is preferably lithium and M cobalt, nickel or iron. Insofar as reference is made below to these substances as examples of A and M, this is done without restriction of the general concept.
The function of the positive electrode is based on the incorporation of the lithium in the matrix of the metal oxide. x is accordingly less than 1, the value x=0 not being achieved in practice. Because of varying proportions of impurities, x and y generally also do not have precisely integral values. Insofar as active masses are designated here by their formula, the specified integral indices should be understood with this reservation.
In practice the ion-conducting active mass of an electrode must be electrically connected to a substrate, which serves as an electron conducting discharge element. The substrate is generally a metal sheet or grid. Generally it simultaneously serves for mechanical securing of the active mass. To achieve this connection, the active mass is often mixed in ground form with organic binders, in particular those based on fluorocarbons (Teflon, Tefzel), and pressed on to the substrate. Often carbon is added to improve the electrical conduction properties. This method is described for different active masses in DE-A-31 22 080 and in particular for LiCoO.sub.2 in EP-A-O 357 952.
The invention aims to improve electrochemical alkali metal cells with a positive electrode based on a complex metal oxide with the general formula A.sub.x M.sub.y O.sub.z in that long-time stability of the electrodes and thus inexpensive production and long life of the cells are achieved with simple manufacture.
This problem is solved by an electrochemical alkali metal cell with a negative electrode containing an alkali metal A, an electrolyte containing the alkali metal A and a positive electrode which has a metallic substrate and an active mass connected to the substrate, the active mass containing a complex metal oxide with the general formula A.sub.x M.sub.y O.sub.z in which A denotes the alkali metal, M a transition metal and O oxygen, wherein the positive electrode is a composite electrode, in which the active mass is connected without any organic binder directly to the substrate, the active mass and its connection to the substrate being produced at the same time in one operation by heating an electrode base containing the transition metal M to a glowing status in contact with an inorganic Compound of the alkali metal whereby a surface layer of the b
REFERENCES:
patent: 3852113 (1974-12-01), Yokota et al.
patent: 4302518 (1981-11-01), Goodenough et al.
patent: 4357215 (1982-11-01), Goodenough et al.
patent: 4668595 (1987-05-01), Yoshino et al.
patent: 5110696 (1992-05-01), Shokoohi et al.
patent: 5213914 (1993-05-01), Heitbaum et al.
patent: 5441830 (1995-08-01), Moulton et al.
Hambitzer Gunther
Heitbaum Joachim
LandOfFree
lectrochemical alkali metal cell and process for its manufacture does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with lectrochemical alkali metal cell and process for its manufacture, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and lectrochemical alkali metal cell and process for its manufacture will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-158927