Chemistry: electrical current producing apparatus – product – and – Terminal protector other than seal through casing
Reexamination Certificate
2000-09-26
2001-11-20
Brouillette, Gabrielle (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Terminal protector other than seal through casing
C429S178000
Reexamination Certificate
active
06319628
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a secondary battery in which a plurality of electrode terminals extending from an end of an electrode sheet are connected to the back of a lid element through one collecting terminal, and a manufacturing method thereof.
2. Description of the Related Art
Electric cars or hybrid cars have been developed in consideration of environmental issues, and compact and lightweight secondary batteries with high performance are needed. Such secondary batteries include a lithium-ion battery, for example. The lithium-ion battery has a small size and a light weight, a large capacity, and good charging characteristics and good cycle characteristics.
A prior art of such a secondary battery is hereinafter described with reference to FIG.
1
and
FIG. 2
a
to
FIG. 2
f
.
FIG. 1
is a vertical sectional view showing the inner structure of a conventional secondary battery, and
FIG. 2
a
to
FIG. 2
f
are diagrams for explaining a method of manufacturing the conventional secondary battery.
As shown in
FIG. 1
, secondary battery
100
herein illustrated comprises case
101
in which electrode element
102
is accommodated. Case
101
is shaped into a hollow cylinder with its bottom closed and its top opened, and is made of iron which is a conductive material.
Electronic element
102
comprises a positive pole sheet, a separator sheet, a negative pole sheet and hollow core
103
, and is configured such that the positive pole sheet, the separator sheet and the negative pole sheet are laminated and wound around core
103
in cylindrical shape. A plurality of electrode terminals
104
and
105
are provided to protrude at a plurality of points on the upper edge of the positive pole sheet and on the lower edge of the negative pole sheet, respectively. Thus, these positive
egative electrode terminals
104
and
105
extend from a plurality of points on the top and the bottom of electrode element
102
, respectively.
Positive pole electrode terminals
104
extending upward from the positive pole sheet are bound into one, and one collecting terminal
106
is welded to the upper end thereof. Insulating tape
107
is wound around the upper portion of electrode terminals
104
thus bound into one and the lower portion of collecting terminal
106
. The upper end of collecting terminal
106
which is not wound in insulating tape
107
is welded to the back of lid element
108
.
Lid element
108
is formed in disk shape with aluminium which is a conductive material, and is integrally provided at its outer edge with gasket
109
made of resin which is an insulating material. Since gasket
109
is fixed to the top end of case
101
, the opening on the top of case
101
is closed by lid element
108
in an insulating state.
Negative pole electrode terminals
105
extending downward from the negative pole sheet are bent toward the center of electrode element
102
. At the center, all electrode terminals
105
are disposed one on another and directly welded to the inner surface of case
101
on the bottom. In electrode element
102
, the gaps between every sheet are impregnated with a nonaqueous electrolytic solution (not shown).
In secondary battery
100
as configured above, the positive pole sheet in electrode element
102
impregnated with the nonaqueous electrolytic solution produces a positive electric potential and the negative pole sheet produces a negative electric potential. Thus, lid element
108
on the top serves as a positive pole and the bottom of case
101
serves as a negative pole.
Description is now made in brief for a method of manufacturing secondary battery
100
as configured above. The positive pole sheet connected with electrode terminals
104
at the plurality of points on the upper edge, the separator sheet, and the negative pole sheet connected with electrode terminals
105
at the plurality of points on the lower edge are laminated and wound around core
103
to form circular cylindrical electrode element
102
as shown in
FIG. 2
a.
Next, as shown in
FIG. 2
b
, positive pole electrode terminals
104
extending from the plural points on the upper edge of electrode element
102
are bound into one to which the lower end of one collecting terminal
106
is resistance welded as shown in
FIG. 2
c
. It should be noted that while
FIG. 1
shows two electrode terminals
104
and
105
and
FIG. 2
a
to
FIG. 2
f
show three for simplifying illustration, a number of electrode terminals
104
and
105
are actually used.
Next, as shown in
FIG. 2
d
, insulating tape
107
is wound around the upper portion of electrode terminals
104
bound into one and the lower portion of collecting terminal
106
. As shown in
FIG. 2
e
, electrode element
102
for which the winding is completed is accommodated into case
101
from the opening on the top.
At this time, negative pole electrode terminals
105
extending from the bottom of electrode element
102
are bent toward the center and disposed one on another, and in this state, abutted against the bottom of case
101
. A welding electrode (not shown) is inserted into a through hole in the center of core
103
to perform resistance welding of negative pole electrode terminals
105
disposed one on another on the bottom of case
101
.
Next, the upper end of collecting terminal
106
which is not wound in insulating tape
107
is resistance welded to the back of lid element
108
, and as shown in
FIG. 2
f
, lid element
108
is fit and fixed to the opening on the top of case
101
. The aforementioned method of manufacturing secondary battery
100
can be changed in the order of the steps as long as the contents cause no contradiction.
For example, it is possible that electrode element
102
is accommodated into case
101
, and then, electrode terminals
104
are bound into one, collecting terminal
106
is welded thereto, and insulating tape
107
is wound around them. In addition, it is not impossible that the upper end of collecting terminal
106
is connected to the back of lid element
108
in advance and the lower end of collecting terminal
106
is welded to electrode terminal
104
.
In secondary battery
100
as configured above, since positive pole electrode terminals
104
extending from the plurality of points on the top of electrode element
102
are connected to lid element
108
through one collecting terminal
106
, lid element
108
can serve as an electrode. In particular, since lid element
108
is connected to collecting terminal
106
with low resistance which in turn is connected to positive electrode terminals
104
, a large current can flow from electrode element
102
to lid element
108
.
As described above, positive electrode terminals
104
extending from the plural points on the top of electrode element
102
wound in cylindrical shape are bound into one as shown in
FIG. 2
a
. As a result, some of electrode terminals
104
are twisted at angles at which they are strained.
Thus, electrode terminals
104
may be broken. To avoid this, long electrode terminals
104
must be formed, which causes the difficulty of automatically binding electrode terminals
104
into one. In addition, since electrode terminals
104
bound into one is welded to one collecting terminal
106
, the welding is complicated and thus a welder (not shown) therefor is required.
The formation of long electrode terminals
104
as mentioned above requires the winding of insulating tape
107
such that they cause no short circuit to the inner surface of case
101
, but this task is complicated and automation is difficult. Furthermore, long electrode terminals
104
as mentioned above make it difficult to reduce the gap between the top of electrode element
102
and the bottom of lid element
108
, thereby obstructing a smaller size and lighter weight of secondary battery
100
.
Additionally, in secondary battery
100
as configured above, since electrode element
102
accommodated in case
101
cannot be fixed as it is, a dedicated spacer (not shown) is required, for example
Brouillette Gabrielle
Hayes, Soloway, Hennessey Grossman & Hage, P.C.
NEC Corporation
Wills Monique
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