Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2001-02-21
2003-12-23
Ryan, Patrick (Department: 1745)
Metal working
Method of mechanical manufacture
Electrical device making
C029S002000
Reexamination Certificate
active
06666899
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing electrode plates for batteries.
2. Description of the Related Art
There has been proposed a new design for nickel metal hydride batteries in which a number of electrode plates are accommodated together with electrolyte within a prismatic battery case having an open top end which is closed by a lid member integrally with the case. The electrode plates include positive electrode plates made of metal foam substrate containing Ni and negative electrode plates made of perforated metal substrate of Ni, coated with an active material containing hydrogen-absorption alloy powder in the form of a paste. The positive electrode plates are covered with bag-shaped separators made of polypropylene non-woven cloth having openings on one side, so that when these electrode plates are alternately stacked upon one another, the separators are interposed between each of the positive electrode plates and negative electrode plates.
Side edges on one side of the positive electrode plates and those of the negative electrode plates are protruded outwards in opposite directions, and these protruded side edges of the electrode plates constitute respective lead sections. The lead sections of the positive electrode plates are composed of the protruded side edges of compressed metal foam substrate, to one side of which lead plates are welded by seam welding or ultrasonic welding. The lead sections of the negative electrode plates are composed of the protruded side edges of perforated metal substrate, which are not coated with the active material. Collector plates made of nickel sheet or nickel-plated steel sheet are abutted perpendicularly on both sides of the positive and negative electrode plates, and welded to the respective lead sections.
The positive electrode plates are fabricated as described below with reference to FIG.
14
. First, lead plates
12
are joined at one or a plurality of locations with suitable separation in a widthwise direction of a strip of metal foam substrate
11
containing nickel. The metal foam substrate
11
is then cut at cutting lines
13
at intervals of a suitable length, whereby electrode substrates
14
as shown in
FIG. 15
are obtained. These electrode substrates
14
are coated with active material and dried, and are further cut to predetermined dimensions.
As shown in
FIG. 15
, considerable warp &dgr; is observed in the electrode substrates
14
after being cut from the metal foam substrate
11
. This is because the metal foam substrate
11
is compressed at portions where the lead plates
12
are welded, and subjected to tension towards these joints. The electrode substrate
14
cannot be coated with active material uniformly because of such warp &dgr;, resulting in defects due to variations in the filling amount of active material. Such warping of electrode substrates also causes various problems in the transfer system from one to another of various process steps such as feeding of substrates, filling of active material, drying of substrates and laminating of electrode plates.
Negative electrode plates are fabricated generally as illustrated in
FIG. 16. A
strip of perforated metal sheet
21
, having solid portions
22
,
22
on both side edges and a punched portion
23
between these solid portions
22
,
22
where a number of pores are formed, is coated with a mixture of negative electrode active materials only on the punched portion
23
, rolled, and cut to suitable length.
When rolling the perforated metal sheet
21
in directions indicated by the arrow in
FIG. 17
, it cannot stretch uniformly because of the solid portions
22
,
22
on both side edges, as a result of which considerable warp &dgr; is observed in the resultant electrode substrate
24
as shown in FIG.
17
. This causes defects and short-circuiting resulting from peeling of active material applied on the substrate, and also causes various other problems similarly to the case with the positive electrode plates.
In view of the above problems of the prior art, an object of the present invention is to provide an improved method of manufacturing electrode plates for batteries.
SUMMARY OF THE INVENTION
The present invention is generally a method of manufacturing electrode plates for batteries, wherein, after joining at least one strip of lead plate in a lengthwise direction to a strip of porous metal sheet having a three-dimensional structure, the porous metal sheet is rolled entirely or in the vicinity of the strip of lead plate. The porous metal sheet is then cut to a predetermined length for obtaining a plurality of electrode substrates, which are coated with active materials for the battery and further cut to a predetermined length for obtaining electrode plates such that the resultant electrode plates have the lead plate on one side thereof. The porous metal sheet is rolled, entirely or in the vicinity of the strip of lead plate, so as to correct stress or strain generated by the tension towards the portions where lead plates have been welded to the porous metal sheet. Therefore, the electrode substrates obtained by dividing this porous metal sheet are free of warping, and they can be coated with electrode active materials uniformly. Also, any troubles during the transfer of the electrode substrates caused by the warp or deformation thereof are prevented.
In another embodiments of the invention, rolling is performed not to the porous metal sheet but to the plurality of electrode substrates after joining the strip of lead plate to the porous metal sheet and cutting the porous sheet into separate pieces of electrode substrates. The electrode substrates may be rolled entirely or only in the vicinity of the lead plate, for obtaining the same or similar effects as described above.
Another embodiment of the present invention is a method of manufacturing electrode plates for a battery, wherein, a strip of porous metal sheet, including perforated portions wherein a large number of pores are formed, solid portions where no such pores are formed on both side edges thereof, and at least one solid row between said solid portions on both side edges, is coated with a mixture of active materials for the battery, rolled, and cut into a plurality of substrates. These substrates are further cut into separate pieces of electrode plates respectively having solid portions on both side edges thereof. Since the porous metal sheet has at least one row of solid portion between the solid portions on both sides thereof, when it is rolled, there is only very little difference in the stretch of the metal sheet in the middle portion and on both side edges. Therefore, the electrode substrates obtained by dividing this metal sheet are free of warping, and they can firmly hold the electrode active materials coated thereon. Thereby, defects of electrode plates resulting from peeling of active material, short-circuits, and troubles when inserting the electrode plates into battery cases are all prevented.
The substrates may be cut into separate pieces of electrode plates such that the electrode plates respectively have solid portions on both side edges thereof and at least one solid row between said solid portions on both side edges.
While novel features of the invention are set forth in the preceding, the invention, both as to organization and content, can be further understood and appreciated, along with other objects and features thereof, from the following detailed description and examples when taken in conjunction with the attached drawings.
REFERENCES:
patent: 5655295 (1997-08-01), Sugikawa
patent: 55124958 (1980-09-01), None
patent: 56-86460 (1981-07-01), None
patent: 61285658 (1986-12-01), None
patent: 63307665 (1988-12-01), None
patent: 1-120761 (1989-05-01), None
patent: 7-73878 (1995-03-01), None
patent: 9-7591 (1997-01-01), None
patent: 9-171821 (1997-06-01), None
patent: 11339798 (1999-12-01), None
English Language Abstract of JP 61-285658.
English Language Abstract of JP 7-73878.
English Language Abstra
Fujioka Noriyuki
Ikoma Munehisa
Inoue Hiroshi
Matsumura Jun
Suzuki Kohei
Cantelmo Gregg
Greenblum & Bernstein P.L.C.
Ryan Patrick
LandOfFree
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