Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Reexamination Certificate
1998-09-02
2001-01-09
Kalafut, Stephen (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
C429S224000, C429S231700, C429S231800, C429S218100, C029S623100
Reexamination Certificate
active
06171724
ABSTRACT:
TECHNICAL FIELD
The invention pertains to batteries, battery electrodes and methods of forming batteries and battery electrodes. The invention has particular application to methods of forming very thin batteries, such as button-type batteries.
BACKGROUND OF THE INVENTION
Small, thin batteries, such as button-type batteries, are commonly used in modern devices. For instance, button-type batteries are utilized as power sources for calculators and watches.
A prior art button-type battery
10
is shown in FIG.
1
. Battery
10
comprises a lower terminal housing member, or can
12
, and an upper terminal housing member, or lid
14
. Can
12
and lid
14
are sealingly joined together at a crimp
16
. Battery
10
is typically in the shape of a circle, with crimp
16
extending entirely around a periphery of the circle. A gasket material
18
is provided within crimp
16
to form a fluid-tight seal within the crimp. A cathode
20
and an anode
22
are provided between terminal housing members
12
and
14
. Cathode
20
has a thickness of greater than 13 mils, and is generally not durable unless it has a thickness of greater than 24 mils. Cathode
20
and anode
22
are separated by a porous separator
24
. An electrolyte
26
is provided within the battery and within porous separator
24
.
Battery cathode
20
typically comprises a mixture of an active material and a conductive medium, or diluent. The active material can be, for example at least one of manganese dioxide and (CF)
x
. The manganese dioxide provides a source of oxidizing component in a battery cell. As manganese dioxide is itself a poor conductor, the conductive medium is added to provide electrical conductivity. The conductive medium can be, for example, elemental carbon. The elemental carbon is typically in the form of graphite, although other materials, such as, acetylene black can also be used. Natural graphites can be used in alkaline cells, but typically cells are made with very pure synthetic graphite to reduce impurities which might lead to corrosion in a battery cell.
A difficulty in forming battery cathodes occurs in binding a conductive medium with an active material. A goal is to develop binders which produce dense, stable cathodes having good electronic and ionic conductivity, and efficient discharge even at high discharge rates. Another goal is to develop binders which form cathodes which can be very thin, and yet durable enough to be utilized with pick and place automation. Also, a goal is to develop binders which are simple to incorporate into manufacturing processes by which battery cathodes are produced. It would be desirable to develop methods of forming battery cathodes which achieve one or more of the above-discussed goals.
There is a continuing goal in small battery fabrication to form the batteries increasingly thinner, while maintaining efficient power discharge and physical durability. Limitations in battery thickness are imposed by limitations of the thicknesses of battery components, such as the anode and the cathode. Accordingly, it would be desirable to develop methods for forming thinner battery components which have good physical durability and efficient power discharge.
SUMMARY OF THE INVENTION
The invention encompasses batteries, battery electrodes and methods of forming batteries and battery electrodes.
In one aspect, the invention includes a battery electrode comprising EPM and a thickness of greater than 0 and less than 24 mils.
In another aspect, the invention includes a battery comprising a first electrode. The first electrode includes a thickness of less than 24 mils, an electrode active material, a conductive medium, and a binder comprising EPM. The battery also includes a second electrode and an electrolyte between the first and second electrodes.
In yet another aspect, the invention includes a method of forming a battery electrode. An electrode material mixture is formed. The electrode material mixture comprises electrode active material, a conductive medium, and EPM. The electrode material mixture is cured to form an electrode having a thickness of less than 24 mils.
REFERENCES:
patent: 4565751 (1986-01-01), Faust et al.
patent: 5246796 (1993-09-01), Nagamine et al.
patent: 5753387 (1998-05-01), Takami et al.
patent: 5824120 (1998-10-01), Mitchell et al.
Dix Eric R.
Li Weihong
Rush-Byers Janine M.
Kalafut Stephen
Martin Angela J.
Micro)n Technology, Inc.
Wells St. John Roberts Gregory & Matkin
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