Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1998-09-10
2001-08-28
Maples, John S. (Department: 1745)
Metal working
Method of mechanical manufacture
Electrical device making
C029S623100
Reexamination Certificate
active
06280484
ABSTRACT:
The present invention relates to a method for the manufacture of a lithium battery comprising the steps of
the contacting cathode material, electrolyte material and anode material, the electrolyte material being a lithium ion-conductive and a for electronic charge carriers (electrons and holes) non-conductive material and separating the cathode material from the anode material, wherein at least the cathode material is a ceramic material and at least either the cathode material or the anode material or both contain lithium,
dynamic compaction of the assembly of cathode material, electrolyte material and anode material.
In this application “battery” is understood to be a stack of one or more cells, wherein just one current collector between the cells suffices. A “cell” is understood to be a stack of, successively, a current collector, an anode, an electrolyte, a cathode and a current collector.
A method as mentioned ill the preamble is known.
In said method an aluminium tube, provided with an insulating inner tube of Teflon is filled with layers of, successively, lithium manganese oxide as the cathode material, lithium oxide-containing boron phosphate as the electrolyte material and graphite as the anode material. Each of the materials is introduced into the tube in the form of a powder of a small particle size (in the order of 1 &mgr;m), is precompacted by tapping a great number of times (in the order of 200 times) and is subsequently subjected to further compaction by means of a hydraulic device before the next material is inserted. After the tube is sealed with a stop the tube is explosion compacted by providing the tube at one end and over its length with an explosive that on detonation produces a pressure build-up, and detonating the same. This causes an extremely high pressure, compacting the materials and enlarging the contact surface between the granules and between the layers.
The method has the disadvantage of being time-consuming and laborious. In addition it is difficult to make thin layers while the risk of short-circuiting between the anode material and the cathode material increases.
The object of the present invention is to overcome these disadvantages and to provide an economically attractive method for the manufacture of dynamically compacted lithium batteries.
To this end the method according to the invention is characterized in that at least one of the materials is introduced into a carrier in the form of a fine powder before being brought into contact with any of the other materials.
Introduction into a carrier facilitates the handling of the powdery material. The carrier may be a liquid carrier or a solid carrier.
According to a preferred embodiment of the method according to the invention, the carrier containing the finely distributed material is processed to form a solid film before introduction into the tube.
Such a film can be handled and can easily be stacked.
According to a favourable embodiment, in the process to form a solid film a plastic is used as the carrier.
The incorporation of fillers in plastics is a widely known technique and may advantageously be used for the fast and simple manufacture of stacked layers of cathode, electrolyte and anode material.
According to a very favourable embodiment the plastic is a lithium ion-conductive plastic.
As the performances of a lithium battery are limited primarily by the degree of electrical conductance of lithium ions in the battery, the invention makes it possible to appreciably improve the cathode layer, the electrolyte layer and/or the anode layer, and as a result the lithium battery.
The invention will now be described in more detail and will be further explained with reference to an example.
REFERENCES:
patent: 4782584 (1988-11-01), Mohri et al.
patent: 5262255 (1993-11-01), Ito et al.
patent: 41 08 805 (1991-09-01), None
patent: 0 409 192 (1991-01-01), None
patent: WO84/02232 (1984-06-01), None
Delft Integraal, Issue 3, 1995 (in Dutch by the Technical universty of Delft, Delft, Netherlands).
Jak Michiel J.
Kelder Erik M
Schooman Johannes
Maples John S.
Myers Jeffrey D.
Stichting Voor De Technische Wetenschappen
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