Chemistry: electrical current producing apparatus – product – and – Means externally releasing internal gas pressure from closed... – Blowout type
Reexamination Certificate
2001-02-15
2004-04-20
Kalafut, Stephen (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Means externally releasing internal gas pressure from closed...
Blowout type
C429S089000, C429S174000
Reexamination Certificate
active
06723465
ABSTRACT:
RELATED APPLICATION DATA
The present application claims priority to Japanese Application No. P2000-041439 filed Feb. 15, 2000, which application is incorporated herein by reference to the extent permitted by law.
BACKGROUND OF THE INVENTION
The present invention relates to a nonaqueous electrolyte battery including a container sealed with a sealing lid, and a method of producing the nonaqueous electrolyte battery.
In recent years, along with progress of the electronic technology, there has been a tendency toward high performance, miniaturization, and portableness of electronic equipment. Batteries used for the electronic equipment have been correspondingly required to have high energy densities, and to meet such a requirement, studies have been actively made to develop nonaqueous electrolyte batteries. In particular, lithium batteries or lithium ion secondary batteries, having performances higher than those of conventional batteries, for example, a high electromotive force of 3 or 4 V, have been adopted for various types of portable electronic equipment, such as a camcorder, a portable telephone, and a notebook type personal computer.
As an electrolytic solution for a lithium or lithium ion battery, there has been used a solution obtained by dissolving an electrolyte exemplified by a lithium based electrolyte salt such as LiPF
6
in a nonaqueous solvent exemplified by a carbonate such as low molecular ethylene carbonate, propylene carbonate, or diethyl carbonate. This is because such an electrolytic solution has a relatively high conductivity and exhibits a stable potential.
In the above-described nonaqueous electrolyte battery, an electrolytic solution contains an organic solvent as described above, and accordingly, when wiring of the battery is short-circuited or the battery is abnormally heated for example, the electrolytic solution may be vaporized and decomposed to generate gas. If the generation rate of such a gas becomes a specific value or more, an inner pressure of an enclosed container may be rapidly raised.
To cope with such an abnormality, there is known a nonaqueous electrolyte battery
100
having a mechanism shown in FIG.
1
.
The nonaqueous electrolyte battery
100
includes an electrode body
104
formed by spirally winding a stack of a positive electrode
101
, a separator
102
, and a negative electrode
103
; a container
105
for containing the electrode body
104
; an insulating plate
106
disposed on a bottom portion of the container
105
, for preventing the electrode body
104
from being brought into electric contact with the container
105
; and a sealing lid group
107
fixed by caulking to an opening at the upper end of the container
105
via an insulating gasket
113
. The sealing lid group
107
includes a disk-like inner lid body
108
disposed opposite to the electrode body
104
; a PTC element
110
disposed on an ring portion of the inner lid body
108
via a valve film
109
formed of a flexible thin film; and a cap-shaped battery lid
111
disposed with its peripheral edge being in contact with the PTC element
110
. Each of the inner lid body
108
and the PTC element
110
has at its central portion a though-hole, and the battery lid
111
has at its stepped portion vent holes
111
a
. One end of a positive electrode lead
112
is connected to the positive electrode
101
of the electrode body
104
, and the other end thereof is connected to a back surface of the inner lid body
108
of the sealing lid group
7
.
In the nonaqueous electrolyte battery
100
having the above-described configuration, if a current larger than a normal current is applied to the battery
100
, for example, by over-charging, the resistance of the PTC element
110
positioned between the inner lid
108
and the battery lid
111
is rapidly increased with temperature rise, to stop the supply of current, thereby preventing an increase in inner pressure in the nonaqueous electrolyte battery
100
. Further, if a decomposition gas is generated and thereby the inner pressure in the nonaqueous electrolyte battery
100
reaches a specific pressure, the decomposition gas passes through the though-hole opened in the inner lid body
108
, to break or melt the valve film
109
positioned over the inner lid body
108
. As a result, the decomposition gas is discharged to the outside of the nonaqueous electrolyte battery
100
through the broken portion of the valve film
109
, the through-hole opened in the PTC element
110
, and the vent holes
111
a
opened in the battery lid
111
, to thereby reduce the inner pressure in the nonaqueous electrolyte battery
100
.
By the way, as shown by arrows I in
FIG. 1
, part of the decomposition gas discharged from the broken portion of the valve film
109
is directly discharged to the outside of the nonaqueous electrolyte battery
100
through the vent holes
111
a
of the battery lid
111
without collision with the inner side of the battery lid
111
. The part of the decomposition gas, which directly passes through the vent holes
111
a,
is discharged obliquely with respect to the height direction of the nonaqueous electrolyte battery
100
, to thereby give a motive force to the nonaqueous electrolyte battery
100
.
FIG. 2
is an enlarged view showing a circle portion H in FIG.
1
. Referring to
FIG. 2
, part of the decomposition gas once collides with the inner side of a projecting portion of the battery lid
111
as shown by an arrow J, and is discharged from the vent holes
111
a
along the direction substantially perpendicular to the height direction of the nonaqueous electrolyte battery
100
as shown by arrows K. Part of the decomposition gas discharged in such a direction, however, collides with a caulking portion formed by inwardly bending an opening edge of the container
105
, and flows in the height direction of the nonaqueous electrolyte battery
100
as shown by arrows L.
As a result, there arises a problem that the nonaqueous electrolyte battery
100
is moved by a motive force generated by the discharge of the decomposition gas, to exert adverse effect on peripheral equipment. Further, the decomposition gas having broken the valve film
109
is discharged from the vent holes
111
a
at a high speed, whereby the motive force given to the nonaqueous electrolyte battery
100
becomes larger. As a result, there arises a problem that the movement of the nonaqueous electrolyte battery
100
by the discharge of the decomposition gas becomes larger.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a nonaqueous electrolyte battery capable of preventing the movement of the nonaqueous electrolyte battery by a motive force generated by discharge of a decomposition gas generated in an abnormal state, and a method of producing the nonaqueous electrolyte battery.
To achieve the above object, according to a first aspect of the present invention, there is provided a nonaqueous electrolyte battery including: an electrode body having at least a positive electrode and a negative electrode; a cylindrical container with its bottom closed, in which the electrode body and a nonaqueous electrolytic solution are contained; and a lid body for closing an opening portion of the container; wherein the lid body has a lid portion which constitutes a peripheral edge portion of the lid body, a projecting portion which constitutes a central portion of the lid body, and a stepped portion which has a vent hole and is positioned between the lid portion and the projecting portion; and a metal plate having a through-hole is disposed between the lid body and the electrode body.
With this configuration, a decomposition gas generated in the container in an abnormal state passes through the through-hole of the metal plate, and at this time, the discharge path of the decomposition gas is suitably restricted in the radial direction of the container, whereby the decomposition gas collides with the inner side of the lid body. As a result, it is possible to sufficiently damp the discharge speed of the decomposition gas and to control th
Huy Sam
Ito Yoshinori
Miyaki Yukio
Segawa Ken
Toda Akira
Kalafut Stephen
Sonnenschein Nath & Rosenthal LLP
Sony Corporation
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