Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Include electrolyte chemically specified and method
Patent
1984-12-10
1991-04-09
Kalafut, Stephen J.
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Include electrolyte chemically specified and method
429193, 429218, H01M 618
Patent
active
050064304
DESCRIPTION:
BRIEF SUMMARY
The invention relates to electrochemical generators comprising a positive electrode and an electrolyte based on vitreous materials.
The employment of glasses as electrode materials has already been studied. However the systems proposed, with molten salts as electrolytes, operate at high temperature and have not been subject of industrial applications.
The work carried out by the inventors on this type of material has led them to observe that by associating them with certain vitreous electrolytes and not molten salts, it was possible to develop electrochemical chains of high performance operating at a temperature of the order of ambient and easy to employ enabling them to be realized by the conventional techniques of electonics.
It is therefore an object of the invention to provide electrochemical generators of high energy density containing as positive electrodes materials resulting from the insertion of elements into a vitreous basic system or corresponding glasses not including inserted elements and as electrolytes vitreous materials ensuring the transport of the element to be inserted.
It is aimed also at providing novel vitreous materials useful in particular for developing positive electrodes.
The electrochemical generators of the invention are characterized in that they comprise:
a positive electrode based on vitreous material of the general formula I
F.sub.a X.sub.b represents a network-forming system and M.sub.c X.sub.d a so called active system, that is to say capable of capturing or providing electrons, in which:
F is an element selected from among Si, Ge, B, P, Al, Nb, As or Sb;
M represents a transition metal which can exist in several degrees of oxidation from 0 to +7 and existing in the vitreous material of the positive electrode in two of the degrees of oxidation which it may present;
X represents oxygen, sulfur or selenium;
a, b, c and d are indices corresponding to the stoichiometry of the elements in the forming system or in the active system concerned;
Y is a number comprised between 0 and 1 (these two values being excluded);
A represents a monovalent element;
x is nil or represents a number which is not nil whose value depends on a number of electrons and/or electronic sites available in the materials;
a negative electrode based on a material selected from the group comprising the element A or a material capable of releasing it;
an electrolyte formed from a vitreous material, capable of transporting A.sup.+ ions and possessing a common former with the vitreous material of the positive electrode.
Advantageously, the use of vitreous materials to form the positive electrode and the electrolyte enables the problems encountered customarily at the interface, resulting in particular, in grain joints with crystalisable materials, to be avoided.
In addition, the use of the same forming system in the electrolyte and the material of the positive electrode enables a delocalization to be obtained of the electolyte-electrode interface due to the continuity of the macromolecular chains of the former from the electrolyte to the electrode.
According also to another advantage of the invention, the generators defined above can be produced in the form of thin layers.
The electrochemical chain can be produced, for example, by evaporation in vacuum of one, two, or three constituents.
The elements A in the positive electrode materials are inserted into the vitreous compounds of formula II (1-y) F.sub.a X.sub.b y(M.sub.c X.sub.d) of which the semiconducting properties are already known. These vitreous compounds constitute therefore a matrix for the elements A.
According to an aspect of great interest, it proves that such vitreous compounds constitute, in particular, accepting structures for elements currently used for the fabrication of electrochemical generator electrodes, such as alkali metals, more especially Na or Li, or a metal such as Ag.
Preferably, the transition metal M of the positive electrode material is selected from the group comprising V, Fe, Co, Ni, Mo, W, Ti, Cr or Mn.
According to a preferred
REFERENCES:
patent: 4310609 (1982-01-01), Liang et al.
patent: 4331750 (1982-05-01), Malugani
patent: 4376709 (1983-03-01), Johnson et al.
patent: 4478920 (1984-10-01), Gaband et al.
patent: 4513070 (1985-04-01), Carette et al.
Duclot Michel J.
Pagnier Thierry
Centre National de la Recherche Scientifique
Kalafut Stephen J.
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