Chemistry: electrical current producing apparatus – product – and – Fuel cell – subcombination thereof – or method of making or... – Process or means for control of operation
Reexamination Certificate
2000-03-24
2003-11-25
Dunn, Tom (Department: 1725)
Chemistry: electrical current producing apparatus, product, and
Fuel cell, subcombination thereof, or method of making or...
Process or means for control of operation
C429S209000, C429S206000, C429S161000, C029S623500
Reexamination Certificate
active
06653023
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rectangular battery, especially rectangular battery comprising a group of electrode plates having a positive electrode plate and a negative electrode plate laminated on each other with a separator provided interposed therebetween such as nickel-hydrogen storage battery and nickel-cadmium storage battery.
2. Description of the Related Art
In recent years, a rectangular alkaline storage battery has been developed to enhance the volumetric efficiency of the interior of the apparatus using battery as a substitute for cylindrical alkaline storage battery comprising a coiled group of electrodes formed by spirally winding a positive electrode plate and a negative electrode plate with a separator provided interposed therebetween. This type of a rectangular alkaline storage battery is prepared by a process which comprises inserting into a rectangular can a group of electrode plates having a positive electrode plate and a negative electrode plate alternately laminated on each other with a separator provided interposed therebetween, connecting a positive electrode lead extending from the positive electrode plate and a negative electrode lead extending from the negative electrode plate to the positive electrode terminal and the negative electrode terminal, respectively, injecting an electrolytic solution into the can, and then sealing the can at the opening portion with a sealing material.
This type of a rectangular alkaline storage battery has found rapidly growing demand as a power supply for portable apparatus such as portable telephone and notebook type personal computer. As a result, the rectangular alkaline storage battery has been required to have a higher capacity and a prolonged life. To this end, this type of a rectangular alkaline storage battery is prepared, e.g., by a process which comprises forming a pair of horizontally arranged negative electrode plates having a belt-like core material in common with each other, bending the central portion (connection portion) of the pair of negative electrode plates into a U-shape, sandwiching a positive electrode plate by the two negative electrode plates connected to each other through a U-shaped bent with a separator provided interposed therebetween to form an electrode plate unit, laminating a positive electrode plate between the electrode plate units with a separator provided interposed therebetween to form a group of electrode plates, and then inserting the group of electrode plates into a rectangular can with an electrolytic solution.
When the thickness of the separator, which doesn't take part in the charge-discharge reaction of the battery, is reduced to further enhance the energy density of the foregoing rectangular alkaline storage battery, the packed amount of the active material can be increased by the amount corresponding to the reduction in the thickness of the separator, making it possible to obtain a high energy density and capacity battery.
However, the smaller the thickness of the separator is for higher energy density and capacity, the lower is the mechanical strength of the separator and the more likely is internal short-circuiting. Thus, the reduction of the thickness of the separator is limited.
When a rectangular alkaline storage battery is prepared by sandwiching a positive electrode plate
10
D by a pair of negative electrode plates
24
,
25
connected to each other through a central U-shaped bent portion (connecting portion)
23
with a separator
30
provided interposed therebetween to form an electrode plate unit, laminating a positive electrode plate
10
D between a pair of the electrode plate units with a separator
30
provided interposed therebetween to form a group of electrode plates, and then inserting the group of electrode plates into a rectangular can with an electrolytic solution as shown in
FIG. 7
, six sheets of the separator
30
are required.
When the number of sheets of separators disposed inside the battery is reduced instead of reducing the thickness of the separator to increase the thickness of the electrode plate by the amount corresponding to the reduction of the thickness of the separator and hence increase the packed amount of the active material, e.g., when a rectangular alkaline storage battery is prepared by a process which comprises sandwiching a positive electrode plate
10
E having a great thickness by a pair of negative electrode plates
26
,
27
connected to each other through a central U-shaped bent portion (connecting portion)
23
to form an electrode plate unit, laminating two such electrode plate units to form a group of electrode plates, and then inserting the group of electrode plates into a rectangular can with an electrolytic solution as shown in
FIG. 8
, only four sheets of the separator are required.
Thus, when the number of sheets of separators disposed inside the battery is reduced instead of reducing the thickness of the separator, the thickness of the electrode plate can be increased by the amount corresponding to the reduction of the number of sheets of separators, making it possible to increase the packed amount of the active material. Thus, a high energy density and capacity battery can be obtained.
However, the foregoing approach is disadvantageous in that it is difficult to prepare an electrode plate having a great thickness by packing an active material at a high density. The foregoing approach is also disadvantageous in that when an electrode plate comprising as a core material a three-dimensionally network porous substrate (e.g., expanded (forming) nickel) is prepared, it is difficult to increase the thickness of the electrode plate itself.
SUMMARY OF THE INVENTION
In the light of the foregoing disadvantages, the present invention has been worked out to provide a rectangular battery such as a rectangular alkaline storage battery comprising an electrode plate which can be easily prepared and having a high packing density of active material and volumetric energy density.
In order to solve the foregoing problems, the rectangular alkaline storage battery of the invention comprises as an electrode plate unit a group of electrode plates having a pair of one electrode plates (e.g., negative electrode plate) and a composite electrode plate made of a plurality of the other electrode plates (e.g., positive electrode plate) sandwiched by the pair of one electrode plates with a separator provided interposed therebetween. There is provided one such an electrode plate unit or a laminate of a plurality of such electrode plate units. In this arrangement of group of electrode plates, there is no need to dispose a separator between the electrode plate units, making it possible to reduce the number of sheets of separators to be disposed in the group of electrode plates.
By reducing the number of sheets of separators to be disposed in the group of electrode plates, the thickness of one electrode plate and the other electrode plate can be increased by the amount corresponding to the reduction in the number of sheets of separators. By increasing the number of sheets of electrode plates instead of increasing the thickness of the electrode plates, the thickness per sheet of electrode plate can be reduced. As a result, the active material can be packed at a high density. At the same time, a three-dimensional network porous substrate (e.g., expanded nickel) can be used as an electrode core material. Accordingly, the volumetric energy density of the electrode plate can be enhanced, making it possible to obtain a high capacity rectangular alkaline storage battery.
Further, when at least one collector lead plate is fixed to the composite electrode plate extending therefrom, and the collector lead plate is disposed in such an arrangement that it doesn't come in contact with the separator at the fixing point thereof, short-circuiting due to piercing through separator by burr developed during the formation of collector lead plate can be prevented. Moreover, when such a collector lead pl
Asanuma Hideyuki
Hamamatsu Takeo
Inoue Masao
Nagase Takashi
Dunn Tom
Edmondson L.
Sanyo Electric Co,. Ltd.
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