Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Cell enclosure structure – e.g. – housing – casing – container,...
Reexamination Certificate
2001-09-27
2003-08-26
Maples, John S. (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Cell enclosure structure, e.g., housing, casing, container,...
C429S178000, C429S174000, C429S183000
Reexamination Certificate
active
06610444
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to secondary cells which comprise a cell can and an electrode unit accommodated in the cell can and serving as a secondary cell element and which are adapted to deliver electric power generated by the electrode unit from a pair of electrode terminals on the can to the outside.
BACKGROUND OF THE INVENTION
In recent years, attention has been directed to lithium ion secondary cells or batteries having a high energy density for use as power sources for portable electronic devices, electric vehicles, etc. Cylindrical lithium ion secondary cells of relatively large capacity, for example, for use in electric vehicles comprise, as shown in
FIG. 5
, a cylindrical cell can
1
having a cylinder
11
and lids
12
,
12
fixed to the respective ends of the cylinder, and a rolled-up electrode unit
2
encased in the can
1
.
A pair of positive and negative electrode terminal assemblies
40
,
40
are attached to the lids
12
,
12
, respectively. The two electrodes of the rolled-up electrode unit
2
are connected to the terminal assemblies
40
,
40
, whereby the electric power generated by the electrode unit
2
can be delivered to the outside from the pair of terminal assemblies
40
,
40
. Each lid
12
has a screw plug
14
screwed in and closing a threaded bore
18
for pouring an electrolyte into the cell can
1
therethrough and a gas vent valve
13
closing a gas vent
17
.
As shown in
FIG. 6
, the rolled-up electrode unit
2
comprises a positive electrode
21
and a negative electrode
23
which are each in the form of a strip and which are rolled up into a spiral form with a striplike separator
22
interposed between the electrodes. The positive electrode
21
comprises a striplike current collector
25
in the form of aluminum foil and coated over opposite surfaces thereof with a positive electrode active substance
24
comprising a lithium composite oxide. The negative electrode
23
comprises a striplike current collector
27
in the form of copper foil and coated over opposite surfaces thereof with a negative electrode active substance
26
containing a carbon material. The separator
22
is impregnated with a nonaqueous electrolyte.
The positive electrode
21
has an uncoated portion having no active substance
24
applied thereto, and base ends of current collector tabs
3
are joined to the uncoated portion. Similarly, the negative electrode
23
has an uncoated portion having no active substance
26
applied thereto, and base ends of current collector tabs
3
are joined to the uncoated portion.
With reference to
FIG. 5
, the current collector tabs
3
of the same polarity have outer ends connected to one electrode terminal assembly
40
. For the sake of convenience,
FIG. 5
shows only some of the electrode tabs as connected at their outer ends to the terminal assembly
40
, with the connection of the other tab outer ends to the assembly
40
omitted from the illustration.
The electrode terminal assembly
40
comprises an electrode terminal member
9
extending through and attached to the lid
12
of the cell can
1
. The terminal member
9
comprises a screw shank
92
extending through a hole in the lid
12
, a flange
91
formed at a base end of the shank
92
and projecting into the can
1
, and a square projection
93
at an outer end of the shank.
A tubular insulating seal member
8
is fitted in the hole of the lid
12
, while a disklike insulating seal member
81
is provided on the surface of the lid
12
. O-rings
82
,
83
are interposed between opposed faces of the tubular insulating seal member
8
and the flange
91
of the terminal member
9
and between opposed faces of the tubular insulating seal member
8
and the lid
12
. Thus, electrical insulation and a seal are provided between the lid
12
and the terminal member
9
. The insulating seal members
8
,
81
are made of polypropylene.
A washer
71
and a spring washer
72
are provided around the shank
92
of the electrode terminal member
9
from outside the lid
12
, and a nut
7
is screwed on the shank
92
. The seal members
8
,
81
and the O-rings
82
83
are held between the flange
91
of the terminal member
9
and the washer
71
by tightening up the nut
7
to produce an enhanced sealing effect. A tab connecting screw member
41
is screwed in the flange
91
of the terminal member
9
. The outer ends of the current collector tabs
3
extending from the rolled-up electrode unit
2
are held between the flange
91
and the screw member
41
.
In assembling the conventional cylindrical secondary cell described, the electrode terminal assembly
40
is mounted on the lid
12
of the cell can
1
, and the nut
7
is thereafter screwed on the terminal member
9
. However, this procedure involves a likelihood that the terminal member
9
will rotate with the rotation of the nut
7
. It is therefore impossible to tighten up the nut
7
with full strength, entailing the problem of increased contact resistance.
In attaching the electrode terminal assembly
40
to the lid
12
before the lid
12
is fixed to the cylinder
11
, the flange
91
of the terminal member
9
can be held against rotation with a tool and thereby prevented from rotating with the nut
7
, whereby the damage to the current collector tabs
3
is avoidable. For example, with cylindrical secondary cells for use in electric vehicles, however, the nut
7
is likely to become loosened due to an influence of vibration. Since the nut
7
then needs to be tightened up to a greater extent, there arises the problem that the terminal member
9
will rotate with the nut
7
similarly.
Accordingly, a secondary cell is proposed wherein the electrode terminal assembly and the lid are fixed to each other with a rotation preventing pin [JP-B No. 9-92238(1997)], whereas the proposal additionally requires an insulating member for electrically insulating the pin from the terminal assembly, giving rise to the problem of increasing the number of components. Further since there is a need to weld the pin and the lid to each other, another problem is encountered in that an increased number of manufacturing steps entails a higher cost.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a secondary cell wherein an electrode terminal member can be prevented from rotating with another member when an electrode terminal assembly is fixed to a lid without the likelihood of increasing the number of components or the number of manufacturing steps.
The present invention provides a secondary cell which comprises an electrode unit
2
enclosed in a cell can
1
and serving as a cell element and which is adapted to deliver electric power generated by the electrode unit
2
to the outside via a pair of electrode terminal portions. At least one of the electrode terminal portions is provided by an electrode terminal assembly
4
attached to the cell can
1
. The electrode terminal assembly
4
comprises:
an electrode terminal member
5
extending through a center hole
19
formed in the cell can
1
and having a flange
51
projecting into the cell can
1
and a screw shank
52
projecting outward from the cell can
1
,
an insulating seal member
6
provided in the center hole
19
of the cell can
1
around the screw shank
52
of the electrode terminal member
5
for providing electrical insulation and a seal between the cell can
1
and the electrode terminal member
5
, and
a nut
7
screwed on the screw shank
52
of the electrode terminal member
5
from outside the cell can
1
,
the insulating seal member
6
being in engagement with the cell can
1
and the flange
51
of the electrode terminal member
5
and nonrotatable relative to the cell can and the flange.
With the electrode terminal assembly
4
attached to the cell can
1
in providing the secondary cell of the invention, the nut
7
is screwed on the screw shank
52
of the electrode terminal member
5
by rotating the nut
7
, whereby the insulating seal member
6
is clamped between the flange
51
of the el
Akita Hiroyuki
Nakanishi Naoya
Nohma Toshiyuki
Yonezu Ikuo
Kubovcik & Kubovcik
Maples John S.
Sanyo Electric Co,. Ltd.
LandOfFree
Secondary cell with non-rotatable terminal member does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Secondary cell with non-rotatable terminal member, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Secondary cell with non-rotatable terminal member will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3110438