Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Plural cells
Reexamination Certificate
2001-03-07
2003-07-29
Chaney, Carol (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Plural cells
C429S149000, C429S156000, C429S157000
Reexamination Certificate
active
06599660
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a battery module and a method for manufacturing the battery module consisting of a plurality of cells connected by welding, each cell comprising a group of electrodes having a positive electrode and a negative electrode laminated via a separator and an electrolytic solution, which are contained and hermetically sealed within a metallic can serving as a terminal of one electrode.
2. Description of the Related Art
Generally, in the alkaline batteries such as a nickel-hydride battery or a nickel-cadmium battery, a positive electrode and a negative electrode with a separator interposed are wound like a vortex, a collector is connected to the end of the positive electrode or negative electrode to form an electrode assembly, and this electrode assembly is contained within a metallic case. Thereafter, a lead part extending from the collector is welded to a sealing member, and the sealing member is attached via an insulating gasket to an opening portion of the battery case, whereby an alkaline battery is hermetically sealed. When such alkaline battery is employed in the electric tools or electric vehicles, owing to the requirement for a high output, it is common use that a battery module is made by connecting a plurality of cells in series.
Such battery module is produced in such a way as to weld one end of a lead plate
85
to a positive electrode cap
82
provided as a positive electrode terminal on a sealing plate
81
of a cell
80
b
, and the other end of the lead plate
85
to a bottom portion
84
of a metallic can
83
of a cell
80
a
, with a central part of the lead plate
85
being bent like U character, whereby a plurality of cells
80
a
,
80
b
are connected in series, as shown in FIG.
15
.
By the way, if the plurality of cells
80
a
,
80
b
connected via the lead plate
85
bent like U character are discharged, a discharge current flows through the lead plate
85
. Therefore, the voltage drop increases, as the lead plate
85
is longer and thinner. This voltage drop is not so problematical when the discharge current is small, but when the battery module is employed in the uses where a large current flows such as the power tools or electric vehicles, there is the problem that the operation voltage may decrease due to the voltage drop.
Therefore, a method was conceived in which the cells were connected directly by soldering the opposite terminals of the cells without the use of the lead plate. However, there was the problem that the soldering had a weaker strength of the connected portion than the welding, and was difficult to effect the connection securely. Also, there was another problem that it was troublesome or poor in working efficiency to solder the opposite electrodes of the cells.
Thus, as a result of various experiments, the present applicants have developed an epochal method of welding directly the adjacent terminals of the cells bypassing a welding current in a direction of charging or discharging the cells. This method is one in which a plurality of cells
90
a
,
90
b
are contained within a holding barrel, not shown, and aligned in one row, then one welding electrode
96
being placed on a positive electrode cap
92
of a cell at an uppermost end thereof, and the other welding electrode
97
being placed on a bottom
94
of a metallic can
93
of a cell at a lowermost end thereof, as shown in FIG.
16
.
Thereafter, a voltage is applied between the welding electrodes
96
,
97
which are subjected to a pressure to conduct a large pulse current. Thereby, a contact part between the bottom
94
of the metallic can
93
of a cell
90
a
and the positive electrode cap
92
of a cell
90
b
is molten and welded.
Thereby, the adjacent terminals of the cell are directly welded together, whereby a voltage drop across this welded portion decreases, so that the battery module has an improved operation voltage.
However, if a plurality of cells are aligned in one row, a pair of welding electrodes are disposed at both ends thereof, a voltage is applied between the pair of welding electrodes which are subjected to pressure to conduct a large pulse current to weld the contact part between the bottom of the metallic can of one cell and the positive electrode cap of the other cell, as described above, an excessive pressure may be directly exerted to the positive electrode cap when the pair of welding electrodes are pressurized. In this case, there was the problem that when the excessive pressure was applied to the positive electrode cap, the positive electrode cap might be compressed or deformed.
Since a pressure valve was disposed within the positive electrode cap, there was the problem that the pressure valve might be operated abnormally if the positive electrode cap was compressed or deformed.
SUMMARY OF THE INVENTION
The present invention has been achieved to solve the above-mentioned problems, and its objective is to provide a battery module of a structure in which a number of cells are welded without damaging a cap portion containing a pressure valve and causing a welding failure.
In order to achieve the above-mentioned objective, according to the present invention, a battery module consisting of a plurality of cells electrically connected, each cell comprising a case (metallic can) serving as a terminal of one electrode and containing a cell element with a positive electrode and a negative electrode disposed to sandwich an electrolyte, and a terminal of the other electrode isolated from said metallic can, said battery module comprising: a connecting member having at least one projection on each of said terminal sides between adjacent two terminals of said cells; wherein each of contact parts between said connecting member and said terminals of said cells are welded at said projection.
Preferably, said connecting member is welded at the contact part with the bottom of said can.
Preferably, said connecting member has an aperture in an area corresponding to said terminal, and is formed to surround said aperture.
Preferably, said connecting member is welded with said can at the bottom of said can, and is configured to reach a part of a lateral face along an outside periphery of said can, and cover the part of said lateral face.
Preferably, said connecting member is configured to reach a part of a lateral face along an outside periphery of said can, and is welded with said can at the lateral face of said can.
Namely, a battery module comprises a connecting member having an aperture at a position corresponding to a cap between a sealing member of one cell and a bottom of a can of the other cell, the aperture having a larger diameter than that of the cap, wherein a contact part between this connecting member and the sealing member of the one cell, as well as a contact part between this connecting member and the bottom of the can of the other cell are connected by welding respectively.
In this way, since the contact part between this connecting member and the sealing member of the one cell, as well as the contact part between this connecting member and the bottom of the can of the other cell are connected by welding respectively, the sealing member of the one cell and the bottom of the can of the other cell are electrically connected via the connecting member, whereby the connecting portion between the sealing member of the one cell and the bottom of the can of the other cell has a collecting path of a length equivalent to the height of the connecting member, namely, the length between the sealing member of the one cell and the bottom of the can of the other cell. Therefore, the voltage drop across the connecting portion decreases, resulting in a battery module with a high operation voltage.
If the sealing member of the one cell and the bottom of the can of the other cell are electrically connected via the connecting member having the aperture having a larger diameter than the cap at the position corresponding to the cap provided on the sealing member, the cap provided on the sealing memb
Oda Takashi
Okajima Hideki
Okumura Yoshinobu
Tanaka Hitoshi
Uesugi Yukichi
Chaney Carol
Nixon & Vanderhye P.C.
Sanyo Electric Co,. Ltd.
Yuan Dah Wei D
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