Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Plural cells
Reexamination Certificate
2003-06-06
2004-08-24
Maples, John S. (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Plural cells
C429S158000, C429S159000, C429S160000, C429S181000
Reexamination Certificate
active
06780538
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a battery module, and in particular to a rechargeable battery for constituting the battery module in which the internal battery resistance can be made small and the battery output can be increased.
2. Description of Related Art
FIG. 10
shows a conventional battery module made by connecting a plurality of rechargeable batteries and coupling them together as one so as to obtain the necessary power. In this battery module, a plurality of cells
41
(
41
a
to
41
j
) made of sealed alkaline rechargeable batteries as shown in
FIG. 11
are arranged side by side, with the long lateral walls of the battery cases
42
adjacent each other. End plates
52
are arranged against the outside of the cells
41
a
and
41
j
at both ends, and the two end plates
52
and
52
are bound together with binding bands
53
so as to couple the cells together as one piece.
For the cells
41
, an electrode plate group
47
, comprising positive electrode plates and negative electrode plates layered with intervening separators, thus constituting elements for electromotive force, is accommodated in a battery case
42
together with a liquid electrolyte, and the open end of the battery case
42
is closed with a lid
46
provided with a safety vent
45
. From the upper end at one side of the positive electrode plates forming the electrode plate group
47
, leads
49
extend upward and are connected to a positive electrode terminal
43
above them, and similarly, from the upper end of the other side of the negative electrode plates, leads
49
extend upward and are connected to an negative electrode terminal
44
above them. The positive electrode terminal
43
and the negative electrode terminal
44
are attached to the lid
46
.
The positive electrode terminals
43
and negative electrode terminals
44
of coupled neighboring cells
41
are connected by connection plates
51
, thereby connecting all cells
41
in series. When the battery cases
42
are coupled, ribs
48
, which protrude vertically from the long lateral walls of the battery cases
42
, are abutted against each other, forming coolant passages running in the vertical direction along the long lateral walls of the battery cases
42
in the space between ribs
48
. The cells
41
a
to
41
j
are cooled by flowing air through these coolant passages.
However, with the configuration for the cells
41
of this conventional battery module, leads
49
extend from a portion at the upper end on one side of the electrodes and are connected to the electrode terminals
43
and
44
, and consequently, there were the problems that the internal resistance of the battery was large, because the average distance from the surface of the electrodes to the collector portions of the leads
49
was long, and that the power output was low, because the utilization rate of the electrode active material was low.
Moreover, because the terminals
43
and
44
protruding to the outside of the lid
46
are connected by connection plates
51
, it is necessary to provide space for this connection at the upper end of the battery cases
42
. Furthermore, since the connection portions are exposed, there is the problem that the space for installing this battery module cannot be made compact.
Moreover, in the portions where electrode pillars of the electrode terminals
43
and
44
extend through the lid
46
, O-rings for providing a seal are usually placed only on the inner side of the lid
46
, and there was the danger that electrolyte may leak during use of the battery.
SUMMARY OF THE INVENTION
In view of these problems of the prior art, it is an object of the present invention to provide a rechargeable battery, of which internal battery resistance is small and of which battery output can be improved. A further object of the present invention is to provide a battery module, of which installation space can be made, and in which there is no danger of electrolyte leakage.
To achieve the above object, the present invention provides a rechargeable battery, comprising:
a prismatic cell case having short lateral walls and long lateral walls; and
a group of electrodes accommodated inside the cell case, the group of electrodes including a plurality of positive and negative electrode plates arranged alternately and substantially in parallel to the long lateral walls of the cell case with an intervening separator therebetween;
wherein lateral edges of the positive electrode plates protrude beyond the negative electrode plates on one side, and lateral edges of the negative electrode plates protrude beyond the group of positive electrode plates on the opposite side, the protruding portions forming lead portions.
Since the lateral portions on one side of the electrode plates serve as lead portions, the average distance from the surfaces of the electrode plates to the collector portions can be made short, the internal battery resistance can be made small, and the utilization rate of the electrode active material becomes large, whereby the power output of the battery can be increased.
The lateral edge portions of the negative electrode plate and positive electrode plate lead portions of the group of electrodes are attached to respective collector plates, and the group of electrodes is thus held by the collector plates. Therefore, the group of electrodes can be held with a compact configuration, and the surface area of the regions for generating an electromotive force can be made large, whereby the battery capacity can be increased.
The collector plates are provided with curved portions at both ends thereof for clamping the group of electrodes. Thereby, the electrodes do not spread and extend toward the outside of the collector plates when the group of electrodes are attached to the collector plates, and the electrodes can be fixed reliably to the collector plates.
By setting D<L ≦4D, where L is the length of a side of the lead portions of the electrodes and D is the length of a side in a direction perpendicular thereto, the average distance from the surfaces of the electrode plates to the collector portions can be made even shorter, and the above-noted effects can be enhanced. If D≧L, the ratio of the space for connecting the cells, that is formed between the upper edge of the electrode plate group and the upper wall of the cell case, against the volume of the electrode plate groups becomes large. As the proportion of the dead space increases, the battery capacity is compromised accordingly, but this problem can be solved when L and D are set as noted above. On the other hand, if L>4D, the aspect ratio (vertical/horizontal) becomes too large, which leads to problems with regard to other structural conditions, such as maintaining the strength of the collector plates or manufacturing of the cell cases. Moreover, if L>4D, there is the problem that temperature variations are large between the two ends of the electrode plate groups in the flow direction of the coolant when the outer walls of the cell case are cooled by letting a coolant flow in the longitudinal direction along the lead portions of the electrode plate groups, but this problem does not occur when L and D are set as noted above.
In the cell case in which a group of electrodes is accommodated, which is made of electrode plates whose dimensions are set to D<L≦4D as noted above, by setting d<l<4d, where l is the length of the long lateral walls of the cell case in the direction parallel to the lead portions of the electrodes, and d is the width of the long lateral walls in the direction perpendicular thereto, the proportion of the dead space is optimized and the battery capacity is increased. Moreover, the temperature variations between the upper portion and the lower portion of the electrode plates can be reduced, when the cell case is cooled by letting the coolant flow in the vertical direction of the long lateral walls of the cell cases.
As mentioned above, the lateral edge portions of the group of positive electrode p
Fujioka Noriyuki
Hamada Shinji
Ikoma Munehisa
Inoue Hiroshi
Morishita Nobuyasu
Greenblum & Bernstein P.L.C.
Maples John S.
Matsushita Electric - Industrial Co., Ltd.
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