U.S. patent application number 11/837584 was filed with the patent office on 2008-02-14 for non-aqueous electrolyte secondary cell.
This patent application is currently assigned to SANYO ELECTRIC CO., LTD.. Invention is credited to Naoya NAKANISHI, Toshiyuki NOHMA, Yasuhiro YAMAUCHI.
Application Number | 20080038628 11/837584 |
Document ID | / |
Family ID | 39051194 |
Filed Date | 2008-02-14 |
United States Patent
Application |
20080038628 |
Kind Code |
A1 |
YAMAUCHI; Yasuhiro ; et
al. |
February 14, 2008 |
NON-AQUEOUS ELECTROLYTE SECONDARY CELL
Abstract
A non-aqueous electrolyte secondary battery has a
pressure-sensitive elastic element reliably operating at a desired
operating pressure. The battery includes an outer can having an
opening; an electrode assembly which is housed in the outer can and
comprises a positive electrode having a positive electrode current
collector and a negative electrode having a negative electrode
current collector; a sealing plate sealing the opening; an external
electrode terminal whose one end is engaged with the throughhole of
the sealing plate and whose other end projects outside the sealing
plate; and a pressure-sensitive elastic element which is disposed
inside the sealing plate in the battery and deforms in accordance
with an increase in the gas pressure in the battery, the external
electrode terminal. The external electrode terminal includes
therein a hole connecting the outside of the battery and the space
in contact with the outer side of pressure-sensitive elastic
element.
Inventors: |
YAMAUCHI; Yasuhiro; (Osaka,
JP) ; NAKANISHI; Naoya; (Osaka, JP) ; NOHMA;
Toshiyuki; (Osaka, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW
SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
SANYO ELECTRIC CO., LTD.
5-5, Keihan-Hondori, 2-chome,
Osaka
JP
570-8677
|
Family ID: |
39051194 |
Appl. No.: |
11/837584 |
Filed: |
August 13, 2007 |
Current U.S.
Class: |
429/56 ;
29/623.2; 427/58; 429/174 |
Current CPC
Class: |
H01M 50/572 20210101;
H01M 50/325 20210101; H01M 50/30 20210101; H01M 10/052 20130101;
H01M 2200/20 20130101; H01M 50/578 20210101; H01M 2200/00 20130101;
Y10T 29/4911 20150115; H01M 50/333 20210101; H01M 50/3425 20210101;
Y02E 60/10 20130101 |
Class at
Publication: |
429/056 ;
029/623.2; 427/058; 429/174 |
International
Class: |
H01M 2/12 20060101
H01M002/12; H01M 10/04 20060101 H01M010/04; H01M 6/14 20060101
H01M006/14 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 11, 2006 |
JP |
2006-220677 |
Sep 11, 2006 |
JP |
2006-246128 |
Claims
1. A non-aqueous electrolyte secondary battery comprising: an outer
can having an opening; an electrode assembly housed in the outer
can, the electrode assembly comprising a positive electrode having
a positive electrode current collector and a negative electrode
having a negative electrode current collector; a sealing plate
sealing the opening; and an external electrode terminal projecting
outside the sealing plate, wherein the external electrode terminal
and the electrode assembly are electrically connected to each other
via an electric conduction path, the electric conduction path
having a pressure-sensitive elastic element halfway therein, the
pressure-sensitive elastic element deforming in accordance with an
increase in a gas pressure in the battery; and the external
electrode terminal includes therein a continuous hole connecting an
outside of the battery and a space in contact with an outer side of
the pressure-sensitive elastic element.
2. The non-aqueous electrolyte secondary battery of claim 1,
wherein the pressure-sensitive elastic element deforms in
accordance with the increase in the gas pressure in the battery so
as to interrupt electrical connection between the external
electrode terminal and the electrode assembly.
3. The non-aqueous electrolyte secondary battery of claim 2,
wherein the sealing plate includes a gas relief valve, the gas
relief valve being opened when the sealing plate is applied with a
gas pressure higher than an operating gas pressure of the
pressure-sensitive elastic element interrupting the electrical
connection between the external electrode terminal and the
electrode assembly.
4. The non-aqueous electrolyte secondary battery of claim 3,
wherein the continuous hole is sealed by a membrane plug disposed
halfway in the continuous hole, the membrane plug being made of a
resin film.
5. The non-aqueous electrolyte secondary battery of claim 4,
wherein the continuous hole is formed in the external electrode
terminal and consists of a vertical hole and a horizontal hole, the
vertical hole extending in an axial direction from an inner end of
the battery, and the horizontal hole having an opening open to the
outside of the battery and being communicated with the vertical
hole.
6. The non-aqueous electrolyte secondary battery of claim 5,
wherein the vertical hole is provided with an enlarged diameter
portion whose inner diameter is enlarged in a shape of a ring; and
the membrane plug is formed in the enlarged diameter portion.
7. The non-aqueous electrolyte secondary battery of claim 1,
wherein the sealing plate includes a gas relief valve, the gas
relief valve being opened when the sealing plate is applied with a
gas pressure higher than an operating gas pressure of the
pressure-sensitive elastic element interrupting the electrical
connection between the external electrode terminal and the
electrode assembly.
8. The non-aqueous electrolyte secondary battery of claim 7,
wherein the continuous hole is sealed by a membrane plug disposed
halfway in the continuous hole, the membrane plug being made of a
resin film.
9. The non-aqueous electrolyte secondary battery of claim 8,
wherein the continuous hole is formed in the external electrode
terminal and consists of a vertical hole and a horizontal hole, the
vertical hole extending in an axial direction from an inner end of
the battery, and the horizontal hole having an opening open to the
outside of the battery and being communicated with the vertical
hole.
10. The non-aqueous electrolyte secondary battery of claim 9,
wherein the vertical hole is provided with an enlarged diameter
portion whose inner diameter is enlarged in a shape of a ring; and
the membrane plug is formed in the enlarged diameter portion.
11. The non-aqueous electrolyte secondary battery of claim 1,
wherein the continuous hole is sealed by a membrane plug disposed
halfway in the continuous hole, the membrane plug being made of a
resin film.
12. The non-aqueous electrolyte secondary battery of claim 11,
wherein the continuous hole is formed in the external electrode
terminal and consists of a vertical hole and a horizontal hole, the
vertical hole extending in an axial direction from an inner end of
the battery, and the horizontal hole having an opening open to the
outside of the battery and being communicated with the vertical
hole.
13. The non-aqueous electrolyte secondary battery of claim 12,
wherein the vertical hole is provided with an enlarged diameter
portion whose inner diameter is enlarged in a shape of a ring; and
the membrane plug is formed in the enlarged diameter portion.
14. A method for producing a non-aqueous electrolyte secondary
battery including an outer can having an opening; an electrode
assembly housed in the outer can, the electrode assembly comprising
a positive electrode having a positive electrode current collector
and a negative electrode having a negative electrode current
collector; a sealing plate sealing the opening; an external
electrode terminal whose one end is engaged with a throughhole of
the sealing plate and whose other end projects outside the sealing
plate; and a pressure-sensitive elastic element deforming in
accordance with an increase in a gas pressure in the battery, the
external electrode terminal having therein a hole connecting an
outside of the battery and a space in contact with an outer side of
the pressure-sensitive elastic element, the method comprising: a
step of forming a membrane plug by injecting a resin solution into
the vertical hole through an opening of the horizontal hole of the
external electrode terminal, the resin solution containing a
solvent and a resin dissolved or dispersed in the solvent, and then
by volatilizing the solvent in the resin solution so as to form a
resin film as the membrane plug.
15. The method for producing a non-aqueous electrolyte secondary
battery of claim 14, wherein the step of forming the membrane plug
is performed after the battery is assembled.
16. The method for producing a non-aqueous electrolyte secondary
battery of claim 14, wherein the non-aqueous electrolyte secondary
battery further includes a gasket having a throughhole disposed on
an outer side of the sealing plate and an insulating plate having a
throughhole disposed on an inner side of the sealing plate, the
external electrode terminal having a flange parallel to an axial
direction ; and the method further comprises a step of swaging in
which the gasket and the insulating plate are disposed on an outer
surface and an inner surface, respectively, of the sealing plate in
such a manner that the throughholes of the gasket and the
insulating plate overlap with the throughhole of the sealing plate;
then the external electrode terminal is fitted in the throughholes
thus overlapped; and then the gasket, the sealing plate, and the
insulating plate are vertically swaged both from a top end surface
of the external electrode terminal and from the flange so as to be
tightly fixed together and also to form an enlarged diameter
portion in the hole of the external electrode terminal, the
enlarged diameter portion being enlarged in a shape of a ring.
17. The method for producing a non-aqueous electrolyte secondary
battery of claim 14, wherein the resin is a fluorine resin, and the
solvent is xylene.
18. The method for producing a non-aqueous electrolyte secondary
battery of claim 15, wherein the resin is a fluorine resin, and the
solvent is xylene.
19. The method for producing a non-aqueous electrolyte secondary
battery of claim 16, wherein the resin is a fluorine resin, and the
solvent is xylene.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to non-aqueous electrolyte
secondary batteries, and more particularly to non-aqueous
electrolyte secondary batteries having a pressure-sensitive elastic
element.
[0003] 2. Description of the Prior Art
[0004] In recent years, non-aqueous electrolyte secondary batteries
have been used not only in compact devices such as mobile phones,
notebook PCs, and digital cameras but also as the power source for
driving electric vehicles and hybrid vehicles.
[0005] When used for the latter application, a plurality of
batteries are connected in series using their external electrode
terminals so as to produce a high output. Non-aqueous electrolyte
secondary batteries are made of highly reactive materials and
therefore required to have a much higher safety level when used as
large size batteries than when used in compact devices.
[0006] In attempts to improve the safety of large size batteries,
various techniques have been proposed to install a
pressure-sensitive elastic element in a battery (for example, refer
to Patent Documents 1 to 8 shown below).
[0007] Patent Document 1: Japanese Utility Model No. 04-24262
[0008] Patent Document 2: Japanese Patent Unexamined Publication
No. 10-241653
[0009] Patent Document 3: Japanese Patent Unexamined Publication
No. 08-171898
[0010] Patent Document 4: Japanese Patent Unexamined Publication
No. 08-293301
[0011] Patent Document 5: Japanese Patent Unexamined Publication
No. 09-55197
[0012] Patent Document 6: Japanese Patent Unexamined Publication
No. 11-307080
[0013] Patent Document 7: Japanese Patent Unexamined Publication
No. 11-154504
[0014] Patent Document 8: Japanese Patent Unexamined Publication
No. 11-329405
[0015] These techniques, however, are required to operate the
pressure-sensitive elastic element smoothly when the battery
internal pressure increases above a certain level. To achieve this,
it is preferable that the space on the outer side of the battery is
communicated with the atmosphere outside the battery so as to
prevent the pressure of the pressure-sensitive elastic element from
increasing on the outer side of the battery when the
pressure-sensitive elastic element deforms. However, when the space
is communicated with the atmosphere outside the battery, the
pressure-sensitive elastic element may be damaged by moisture or
oxygen entering from the outside of the battery. As a result, the
pressure-sensitive elastic element may not operate at a desired
operating pressure.
[0016] The batteries shown in the aforementioned patent documents
are not intended to be connected in series at short distances with
other batteries. Therefore, these documents contain no technical
suggestion of operating a pressure-sensitive elastic element in
combination with the external electrode terminal. Under such
circumstances, there is a growing expectation for batteries having
a pressure-sensitive elastic element that can operate reliably and
speedily when an abnormal stats occurs in a battery, particularly
in a large size battery having an external electrode terminal.
SUMMARY OF THE INVENTION
[0017] An object of the present invention is to provide a
non-aqueous electrolyte secondary battery having the following
characteristics. The battery has an external electrode terminal so
as to be connected in series at short distances with other
batteries and also has a pressure-sensitive elastic element
operating reliably and speedily when a desired operating pressure
is reached so as to excel in usability and safety.
[0018] In order to achieve the object, the non-aqueous electrolyte
secondary battery having the fundamental structure (referred to as
a first aspect) of the present invention includes;
[0019] an outer can having an opening;
[0020] an electrode assembly housed in the outer can, the electrode
assembly comprising a positive electrode having a positive
electrode current collector and a negative electrode having a
negative electrode current collector;
[0021] a sealing plate sealing the opening; and
[0022] an external electrode terminal projecting outside the
sealing plate.
[0023] The external electrode terminal and the electrode assembly
are electrically connected to each other via an electric conduction
path, the electric conduction path having a pressure-sensitive
elastic element halfway therein, the pressure-sensitive elastic
element deforming in accordance with an increase in the gas
pressure in the battery.
[0024] The external electrode terminal includes therein a
continuous hole connecting the outside of the battery and the space
in contact with the outer side of the pressure-sensitive elastic
element.
[0025] This structure enables the pressure applied to the outer
side of the pressure-sensitive elastic element to be kept equal to
the pressure outside the battery (the atmospheric pressure), so
that the pressure-sensitive elastic element easily deforms in
accordance with an increase in the battery internal pressure. As a
result, when the battery internal pressure increases to a
predetermined value, the pressure-sensitive elastic element
operates reliably and speedily, thereby interrupting the current
flow and/or releasing the gas in the battery. In this structure,
the external electrode terminal includes therein the continuous
hole connecting the space in contact with the outer side of the
pressure-sensitive elastic element and the outside of the battery,
thereby eliminating the need to provide a pressure release hole. In
other words, this structure allows the external electrode terminal
to have not only the original function as an electrode terminal but
also the function as a pressure release passage, thereby
simplifying the battery structure.
[0026] In the aforementioned structure of the present invention,
the pressure-sensitive elastic element may be designed to deform in
accordance with the increase in the gas pressure in the battery so
as to interrupt electrical connection between the external
electrode terminal and the electrode assembly (a second aspect of
the present invention).
[0027] This structure enables the pressure-sensitive elastic
element to speedily interrupt current flow when gas is generated in
the battery, thereby suppressing battery runaway.
[0028] The pressure-sensitive elastic element can be a type which
breaks to release the gas generated in the battery, a type which
deforms to interrupt the current flow between the electrode and the
external electrode terminal, or other types. For example, a
diaphragm or a return safety valve having a disc spring can be
used. It is more preferable to use a diaphragm that deforms in
accordance with an increase in the gas pressure in the battery and
interrupts the electrical connection between the external electrode
terminal and the electrode assembly.
[0029] In the non-aqueous electrolyte secondary battery of the
second aspect of the present invention, the sealing plate may
include a gas relief valve, the gas relief valve being opened when
the sealing plate is applied with a gas pressure higher than an
operating gas pressure of the pressure-sensitive elastic element
interrupting the electrical connection between the external
electrode terminal and the electrode assembly (a third aspect of
the present invention).
[0030] In this structure, if the gas pressure in 'the battery
increases even after the pressure-sensitive elastic element
interrupts the current flow, then the gas relief valve operates to
release the gas in the battery to the outside, thereby further
increasing the safety of the battery.
[0031] In the non-aqueous electrolyte secondary battery of each of
the first to third aspects of the present invention, the continuous
hole may be sealed by a membrane plug (12) disposed halfway in the
continuous hole, the membrane plug being made of a resin film (a
fourth aspect of the present invention).
[0032] In this structure, when the battery is operating normally,
the membrane plug (12) formed in the continuous hole protects the
battery from the entry of moisture or oxygen, thereby preventing
the pressure-sensitive elastic element from being damaged by
moisture or oxygen entering through the continuous hole. The
membrane plug made of a resin film, on the other hand, is too
fragile to withstand the pressure change due to the deformation of
the pressure-sensitive elastic element. Therefore, when an abnormal
stats occurs in the battery and hence the internal pressure
increases, the membrane plug is easily broken. Thus, the membrane
plug never disturbs the operation of the pressure-sensitive elastic
element.
[0033] In the non-aqueous electrolyte secondary battery of the
fourth aspect of the present invention, the continuous hole may be
formed in the external electrode terminal (1) and consist of a
vertical hole (1a) and a horizontal hole (1b), the vertical hole
(1a) extending in the axial direction from the inner end of the
battery, and the horizontal hole (1b) having an opening open to the
outside of the battery and being communicated with the vertical
hole (1a) (a fifth aspect of the present invention).
[0034] Such a hole consisting of a vertical hole and a horizontal
hole can be easily formed inside the external electrode terminal
and can also function conveniently as a hole connecting the inside
and outside of the battery because the horizontal hole is open to
the outside of the battery.
[0035] In the non-aqueous electrolyte secondary battery of the
fifth aspect of the present invention, the vertical hole (1a) may
be provided with an enlarged diameter portion (1c) whose inner
diameter is enlarged in the shape of a ring; and the membrane plug
(12) may be formed in the enlarged diameter portion (1c) (a sixth
aspect of the present invention).
[0036] The enlarged diameter portion formed in the vertical hole
functions as a fixing frame for the positioning and fixing of the
membrane plug, thereby facilitating the formation and preventing
the displacement of the membrane plug in the vertical hole.
[0037] A method of the present invention for producing a
non-aqueous electrolyte secondary battery (a seventh aspect of the
present invention) may be a method for producing a non-aqueous
electrolyte secondary battery including an outer can having an
opening; an electrode assembly (10) housed in the outer can, the
electrode assembly (10) comprising a positive electrode having a
positive electrode current collector and a negative electrode
having a negative electrode current collector; a sealing plate (3)
sealing the opening; an external electrode terminal (1) whose one
end is engaged with the throughhole of the sealing plate (3) and
whose other end projects outside the sealing plate (3); and a
pressure-sensitive elastic element deforming in accordance with an
increase in the gas pressure in the battery, the external electrode
terminal (1) having therein a hole connecting the outside of the
battery and the space in contact with the outer side of the
pressure-sensitive elastic element. The method may include a step
of forming a membrane plug by injecting a resin solution into the
vertical hole through the opening of the horizontal hole of the
external electrode terminal (1), the resin solution containing a
solvent and a resin dissolved or dispersed in the solvent, and then
by volatilizing the solvent in the resin solution so as to form a
resin film as the membrane plug.
[0038] This structure enables the effective production of the
non-aqueous electrolyte secondary battery with an external
electrode terminal having a membrane plug in its continuous hole.
Examples of the aforementioned solvent include toluene, xylene,
chlorobenzene, chloromethane, chloroethane, methanol, methyl
acetate, ethyl ether, and acetone. Examples of the aforementioned
resin include fluorine resin, polyolefin resin, phenolic resin,
epoxy resin, polyimide resin, polyvinyl chloride resin, and silicon
resin.
[0039] In the method of the present invention for producing a
non-aqueous electrolyte secondary battery, the step of forming the
membrane plug may be performed after the battery is assembled (an
eighth aspect of the present invention).
[0040] The formation of the membrane plug after the assembly of the
battery eliminates the risk that the membrane plug breaks during
the battery assembly process, thereby increasing the membrane plug
formation yield.
[0041] In the aforementioned method of the present invention for
producing a non-aqueous electrolyte secondary battery, the
non-aqueous electrolyte secondary battery may further include a
gasket having a throughhole disposed on the outer side of the
sealing plate (3) and an insulating plate having a throughhole
disposed on the inner side of the sealing plate (3), the external
electrode terminal (1) having a flange (1d) parallel to the axial
direction; and the method may further include a step of swaging in
which the gasket and the insulating plate are disposed on the outer
surface and the inner surface, respectively, of the sealing plate
(3) in such a manner that the throughholes of the gasket and the
insulating plate overlap with the throughhole of the sealing plate
(3); then the external electrode terminal (1) is fitted in the
throughholes thus overlapped; and then the gasket, the sealing
plate (3), and the insulating plate are vertically swaged both from
the top end surface of the external electrode terminal (1) and from
the flange so as to be tightly fixed together and also to form an
enlarged diameter portion (1c) in the hole of the external
electrode terminal (1), the enlarged diameter portion (1c) being
enlarged in the shape of a ring (a ninth aspect of the present
invention).
[0042] In this structure, the enlarged diameter portion can hold a
large amount of resin solution to ensure the formation of the
membrane plug in this portion. Furthermore, the membrane plug,
which is large than the diameter of the hole, can be tightly fixed
and never be displaced vertically. Thus, the membrane plug can be
formed easily.
[0043] The enlarged diameter portion preferably has a 1.05 to 1.2
times larger diameter than the vertical hole, and the diameter of
the vertical hole is preferably 0.8 to 3 mm. These conditions allow
the membrane plug to be formed reliably and easily.
[0044] In the aforementioned method of the present invention for
producing a non-aqueous electrolyte secondary battery, the resin
may be a fluorine resin, and the solvent may be a xylene-based
solvent (more specifically, paraxylene hexafluoride) (a tenth
aspect of the present invention).
[0045] A xylene-based solvent has the ability to dissolve a
fluorine resin and is easily volatilized, making it easy to form
the membrane plug. In addition, the fluorine resin has good sealing
property suitable as a membrane plug material. Such a fluorine
resin can be a copolymer including a fluoroalkyl or perfluoroalkyl
group, such as a fluoroalkyl acrylate copolymer, a perfluoroalkyl
acrylate copolymer, or a perfluoroalkyl methacrylate copolymer.
[0046] As described hereinbefore, the present invention provides a
non-aqueous electrolyte secondary battery that has a
pressure-sensitive elastic element operating reliably and speedily
and that prevents time degradation due to moisture, oxygen or the
like entering from the outside of the battery.
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] FIGS. 1A, 1B, and 1C are sectional views of a battery
according to the present invention.
[0048] FIG. 2 is an enlarged sectional view of an essential part of
the battery according to the present invention.
[0049] FIGS. 3A and 3B show the operation of the diaphragm of the
battery according to the present invention.
[0050] FIGS. 4A, 4B, and 4C show processes of forming a membrane
plug of the battery according to the present invention.
[0051] FIG. 5 is an exploded perspective view of the battery
according to the present invention.
[0052] FIG. 6 is another enlarged sectional view of the essential
part of the battery according to the present invention.
[0053] FIGS. 7A, 7B and 7C are a plan view, a front view, and a
right side view, respectively, of the current collecting tab holder
of the battery according to the present invention.
[0054] FIGS. 8A and 5B show the diaphragm of the battery according
to the present invention respectively before and after being
operated.
[0055] FIGS. 9A and 9B show a process of swaging.
[0056] FIGS. 10A and 10B show another process of the swaging.
REFERENCE MARKS IN THE DRAWINGS
[0057] 1 external positive electrode terminal [0058] 1a vertical
hole [0059] 1b horizontal hole [0060] 1c enlarged diameter portion
[0061] 1d flange [0062] 2 gasket [0063] 3 sealing plate [0064] 4
insulating plate [0065] 5 sealing lead [0066] 6 pressure-sensitive
elastic element (diaphragm) [0067] 7 current collecting tab holder
[0068] 9 current collecting tab [0069] 10 electrode assembly [0070]
11 outer can [0071] 12 membrane plug
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0072] A preferred embodiment of the present invention is described
in detail as follows with reference to drawings.
[0073] FIGS. 1A-1C are sectional views of a battery according to
the present invention; FIG. 2 is an enlarged sectional view of an
essential part of the battery; FIGS. 3A and 3B show the operation
of a diaphragm, which is an example of the pressure-sensitive
elastic element of the battery; FIGS. 4A-4C show processes of
forming a membrane plug of the battery; FIG. 5 is an exploded
perspective view of the battery; FIG. 6 is another enlarged
sectional view of the essential part of the battery; FIGS. 7A-7C
show the current collecting tab holder of the battery; and FIGS.
9A, 9B, 10A and 10B show processes of swaging.
[0074] As shown in FIGS. 1A-1C, the battery of the present
invention includes an outer can 11 and a coiled electrode assembly
10 housed in the outer can 11 laterally to the can axis. The
electrode assembly 10 comprises positive and negative electrodes
coiled together. The outer can 11 is sealed with a sealing plate 3
having a gas relief valve. The sealing plate 3 has an external
positive electrode terminal 1 and an external negative electrode
terminal projecting outside the battery therefrom.
[0075] As shown in FIG. 5, the electrode assembly 10 has
positive-electrode current-collector protrusions 10a projecting
from one end thereof. The positive-electrode current-collector
protrusions 10a are connected to a current collector connecting
portion 9b of a current collecting tab 9. The positive-electrode
current-collector protrusions 10a are a bundle of the protrusions
of the positive electrode current collector protruding from one end
of the electrode assembly 10.
[0076] As shown in FIG. 2, the external positive electrode terminal
1, which is an external electrode terminal and in contact with a
gasket 2, is fitted in the sealing plate 3. The external positive
electrode terminal 1 is also in contact with an insulating plate 4
and a sealing lead 5 on the inner side of the sealing plate 3. The
sealing lead 5 is welded to a diaphragm 6, thereby providing an
electrical connection between the diaphragm 6 and the external
positive electrode terminal 1.
[0077] As shown in FIGS. 2 and 3A, the inner center portion of the
diaphragm 6 is in contact with the center portion of an
interrupting foil 8. The periphery of the interrupting foil 8
covers a throughhole 9c formed in an insert member 9a of the
current collecting tab 9 disposed below the diaphragm 6. The
diaphragm 6 and the interrupting foil 8 form the pressure-sensitive
elastic element.
[0078] FIG. 5 is an exploded perspective view of an essential part
of the battery before the insert member 9a of the current
collecting tab 9 is inserted into a tab receiving portion 7a of a
current collecting tab holder 7. FIGS. 7A-7C show the current
collecting tab holder 7. As shown in FIG. 5, the current collecting
tab 9 includes the insert member 9a to be inserted into the tab
receiving portion 7a of the current collecting tab holder 7 and the
current collector connecting portion 9b to be connected to the
positive-electrode current-collector protrusions 10a of the
electrode assembly 10. The tab receiving portion 7a is provided on
both the inner and outer surfaces thereof with a holder hole 7c.
The holder hole 7c is equal to or larger in area than the
throughhole 9c. As shown in FIG. 5, the insert member 9a of the
current collecting tab 9 is inserted into the tab receiving portion
7a of the current collecting tab holder 7.
[0079] The connected portion between the external electrode
terminal and the sealing plate is shown in a lateral sectional view
in FIGS. 3A and 3B and shown in a longitudinal sectional view in
FIG. 6. The external positive electrode terminal 1 includes therein
a hole consisting of a vertical hole 1a and a horizontal hole 1b.
The vertical hole la extends in the axial direction from the inner
end to the outer end of the battery. The horizontal hole 1b has an
opening open to the outside of the battery and is communicated with
the vertical hole 1a. The vertical hole 1b may be provided with a
membrane plug 12 made of a resin film as shown in FIG. 8A so as to
seal the hole. The horizontal hole 1b may be open at one side
only.
[0080] FIGS. 3A and 3B show the operation of the diaphragm of the
battery of the present invention. When the battery internal
pressure is normal, as shown in FIG. 3A, the diaphragm 6 is
supplied with a current from the current collecting tab 9 via the
interrupting foil 8. When the battery internal pressure increases,
on the other hand, as shown in FIG. 3B, the center portion of the
diaphragm 6 rises toward the outside of the battery. This causes
the interrupting foil 8 in contact with the diaphragm 6 to break,
thereby interrupting the current flow from the current collecting
tab 9 to the diaphragm 6. In the case where the vertical hole has
the membrane plug 12 halfway therein as shown in FIG. 8A, the
rising of the diaphragm 6 causes the membrane plug 12 to deform
upward or to break.
[0081] In the aforementioned structure, the current collecting tab
holder 7 protects the interrupting foil 8 formed in the planar
insert member 9a of the current collecting tab 9 from impact or
vibration. This prevents the interrupting foil 8 from being
erroneously broken by impact.
[0082] How to assemble the current interrupting mechanism of the
battery of the present invention is described with reference to
FIG. 5. First of all, the coiled electrode assembly is prepared.
The electrode assembly is disposed in such a manner that the
protrusions of the positive electrode current collector protrude
from one end thereof and the protrusions of the negative electrode
current collector protrude from the other end thereof.
[0083] Next, the gasket 2 and the external positive electrode
terminal 1 are stacked together from the side of the sealing plate
3 that corresponds to the outside of the battery. The insulating
plate 4 and the sealing lead 5 are stacked together from the side
of the sealing plate 3 that corresponds to the inside of the
battery. The external electrode terminal 1 is provided at its
bottom with a cylindrical portion 1c, which penetrates the
respective holes of the gasket 2, the sealing plate 3, the
insulating plate 4, and the sealing lead 5.
[0084] These members thus stacked are compressed vertically (in up
and down directions) from the top end surface of the external
positive electrode terminal 1 and from the flange 1d side until the
gasket 2 and the insulating plate 4 achieve a predetermined
compressibility. The cylindrical portion 1c at the bottom of the
external electrode terminal 1 is spread outward (swaged) to form an
enlarged diameter portion 1c and fixed (refer to FIG. 4A).
[0085] The enlarged diameter portion 1c is formed as follows.
First, a punch is used which has a tip portion slightly smaller in
diameter than the vertical hole 1a and a step portion to enlarge
the diameter of the vertical hole 1a. The punch is inserted into
the vertical hole 1a of the external positive electrode terminal 1
so as to slightly swage the tip of the external positive electrode
terminal 1. Then, another punch having a tip portion slightly
smaller in diameter than the vertical hole 1a is inserted into the
vertical hole 1a of the external positive electrode terminal 1 so
as to fully swage the portion to be swaged (refer to FIGS. 9A, 9B,
10A, and 10B where the external positive electrode terminal 1 is
drawn upside down so that the portion to be swaged is shown in the
top).
[0086] The diaphragm 6 is stacked on a flange 5a of the sealing
lead 5, and their contact area is entirely laser welded from the
diaphragm 6 side so as to be sealed.
[0087] The interrupting foil 8 is stacked on the throughhole 9c,
which has a step portion, of the insert member 9a of the positive
electrode current collecting tab 9, and their contact area is
ultrasonic welded.
[0088] The insert member 9a of the positive electrode current
collecting tab 9 is inserted into the tab receiving portion 7a of
the current collecting tab holder 7. The tab receiving portion 7a
is slightly larger than the insert member 9a, so that when the
insert member 9a is inserted, the current collecting tab holder 7
and the positive electrode current collecting tab 9 are fixed to
each other.
[0089] In the same manner as in the external positive electrode
terminal described above, in the external negative electrode
terminal, a gasket, an insulating plate, and a sealing lead are
stacked together and swaged.
[0090] Hooks 4a of the insulating plate 4 are engaged with the
fixing portions 7b of the current collecting tab holder 7 so as to
fix the current collecting tab holder 7 and the insulating plate 4
to each other. The diaphragm 6 comes into contact at a center
bottom 6a thereof with the interrupting foil 8 via the holder hole
7c of the current collecting tab holder 7.
[0091] The interrupting foil 8 is welded to the diaphragm 6 by
applying laser spot welding from the side of the positive electrode
current collecting tab 9 that is opposite to the side on which the
interrupting foil 8 has been welded. As a result, the gas pressure
in the battery acts on the interrupting foil 8 and the inner side
of the diaphragm 6.
[0092] The positive-electrode current-collector protrusions 10a of
the electrode assembly 10 are inserted into the bundled core of the
positive electrode current collecting tab 9. The current collector
connecting portion 9b is swaged to hold the positive-electrode
current-collector protrusions 10a. Then, laser welding is applied
to the side surface of the current collector connecting portion 9b
so as to connect the positive electrode current collecting tab 9
and the electrode assembly 10. Then, in the negative electrode, a
negative electrode current collecting tab is connected in the same
manner.
[0093] A non-aqueous electrolytic solution is poured into the outer
can 11, and the sealing plate 3 is laser welded to the outer can
11.
[0094] As shown in FIGS. 4B and 4c, a resin solution, which is
formed by dissolving a fluorine resin (a fluoroalkyl acrylate
copolymer) in a xylene-based solvent, is poured into the enlarged
diameter portion 1c of the vertical hole 1a through the opening of
the horizontal hole 1b of the external positive electrode terminal
1. Then, the solvent in the resin solution is volatilized to form
the membrane plug 12, thereby completing the battery of the present
invention.
[0095] Ten batteries having a 80 .mu.m thick interrupting foil 8
were produced as the batteries of the embodiment.
[0096] Another ten batteries having the same structure as the
batteries of the embodiment except for the absence of the
continuous hole were produced as comparative batteries.
[0097] The current interrupting pressures of the batteries of the
embodiment were measured and found to be 0.5 to 0.7 MPa. On the
other hand, the current interrupting pressures of the comparative
batteries were not able to be measured because the gas relief valve
was actuated when the pressures reached around 1.0 MPa. Therefore,
the current interrupting pressures were measured again after a
metal plate was welded to the gas relief valve so as to prevent the
actuation of the gas relief valve. As a result, the current
interrupting pressures of the comparative batteries increased to
1.5 MPa to 2.8 MPa with a larger variation than in the batteries of
the embodiment.
[0098] Another five batteries of the present invention in which the
vertical hole has the membrane plug 12 were stored for ten days at
a temperature of 60.degree. C. and at a humidity of 80%. Then, the
batteries were filled with gas and pressurized to examine the
operating pressure of the interrupting foil.
[0099] As a result, it was confirmed that in the five batteries the
interrupting foil operated within the error of 5% of the desired
pressure value.
Industrial Applicability
[0100] As described hereinbefore, the non-aqueous electrolyte
secondary battery of the present invention, which has a
pressure-sensitive elastic element with stable operation and little
time degradation, is industrially useful.
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