JP2010225496A - Safety mechanism for laminated exterior power storage devices - Google Patents

Abstract

A laminate capable of obtaining sufficient air-tightness in a normal use state and capable of reliably discharging the gas from a specific portion when a gas is generated inside the exterior body of the laminated exterior power storage device. Provide a safety mechanism for an external power storage device.
SOLUTION: An exterior film 21A that is overlapped with each other has an exterior body 20 that is airtightly joined to each other at a joint portion 22 formed at each outer peripheral edge portion, and is formed inside the exterior body 20. A safety mechanism for a laminated exterior electricity storage device configured to accommodate the electricity storage device element 11 and the electrolyte in the accommodation portion 23, and is fixed to the outer surface of at least one exterior film 21A to the joint portion 22 of the exterior film. The needle-like member 25 is provided so that at least one end portion is located in the portion 24 other than the joint portion.
[Selection] Figure 1

Description

  The present invention relates to a safety mechanism for a laminated exterior power storage device, and more specifically, a safety of a laminated exterior electrical storage device in which electrical storage device elements such as a battery and a capacitor (capacitor) are accommodated by an exterior body composed of two exterior films. Regarding the mechanism.

  In recent years, an electricity storage device element such as a battery element in which a positive electrode plate and a negative electrode plate are wound or alternately laminated via a separator is accommodated in an outer package made of two outer films together with an electrolytic solution. Laminate exterior power storage devices (batteries and capacitors) are used as power sources for portable devices and electric vehicles.

  In such a laminated exterior electricity storage device, a gas such as a flammable gas is generated inside the exterior body due to electrolysis or thermal decomposition of the electrolytic solution by being overcharged or exposed to a high temperature. This may cause an increase in the internal pressure of the exterior body. Thus, in order to solve such a problem, a portion having a weak bonding force (hereinafter also referred to as “weakly bonded portion”) is formed in a part of the bonded portion of the two exterior films in the exterior body, When the gas pressure rises, a safety mechanism that makes this weak joint function as a safety valve for degassing, or automatically opens when the internal pressure rises above a predetermined value, such as flammable gas A laminated exterior power storage device provided with a safety mechanism having a safety valve that exhausts the air to the outside has been proposed (see, for example, Patent Document 1 to Patent Document 5).

FIG. 9 shows an exploded configuration of an example of a laminated exterior power storage device provided with a safety mechanism in which a weakly joined portion is formed at a joined site in an exterior body. The laminate body of the laminated exterior power storage device 50 is such that the outer periphery portion is heat-sealed over the entire periphery in a state where the upper exterior film 51A and the lower exterior film 51B are overlapped to form the joint portion 52. Thus, a housing portion for housing the electricity storage device element is formed therein, and a thin electricity storage device element (for example, a battery element or a capacitor element) 55 is housed together with the organic electrolyte in the housing portion of the exterior body. Has been.
The laminated exterior power storage device 50 is provided with a weak joint portion 53 in a part of the joint portion 52, and even when a large amount of gas is generated in the exterior body by the weak joint portion 53 acting as a safety valve. The outer body is prevented from rupturing by releasing the pressure from the weakly bonded portion 53 and releasing the pressure. Specifically, the weak joint portion 53 has a lower seal strength than the other portions in the joint portion 52, and the internal pressure of the housing portion in which the power storage device element (battery element or capacitor element) is housed in the exterior body is reduced. When the predetermined value is reached, the weakly bonded portion 53 is preferentially separated to form an exhaust port.
Moreover, in the example of this figure, the exterior body has a rectangular outline shape, and a plurality of positive electrode plates constituting an electric storage device element (battery element or capacitor element) 55 from each of the two short sides. A positive electrode power tab 56 which is a common positive electrode lead member electrically connected to each of the plurality of negative electrode plates, and a negative electrode power supply tab 57 which is a common negative electrode lead member electrically connected to each of the plurality of negative electrode plates are pulled out. It is.

  In the laminated exterior electricity storage device having such a configuration, the weakly bonded portion constituting the safety mechanism is formed with an exhaust port to be surely peeled when the internal pressure of the accommodating space reaches a predetermined value, Moreover, in a normal use state, a sealing strength that is surely sealed and ensures sufficient reliability is required. However, it is not easy to reliably form a weakly bonded portion having such a sealing strength from the viewpoint of manufacturing.

In addition, as a safety mechanism of the laminated exterior power storage device, at least one of the regions where the joint portion is formed, the non-joint portion is continuous with the housing portion in which the power storage device element is housed and is formed in a cove shape with respect to the housing portion. By providing, a pressure concentration part is formed, and in the region where the non-bonded part is formed, a pressure release part that communicates the inside and the outside by peeling of the exterior film is formed ( (See Patent Document 6).
However, in such a safety mechanism, when the internal pressure suddenly increases, the pressure concentration portion is unlikely to peel off, so the exterior body may be ruptured. In order to make it peel in this, since it is necessary to make the fusion width in a pressure concentration part considerably small, there exists a problem that it is difficult to ensure sufficient airtightness in a normal use state.

Furthermore, as a safety mechanism of other laminated exterior power storage devices, as an exterior film constituting the exterior body, a heat-fusible resin film, a metal foil, and a rigid resin film are laminated in this order from the inner surface side. And a structure in which a cut is provided in the metal foil of the exterior film (see Patent Document 7).
However, in such a safety mechanism, the airtightness in the exterior body is not sufficiently ensured, and there is a possibility that the electrolyte solution leaks.

Japanese Patent No. 3554155 Japanese Patent Laid-Open No. 05-013061 Japanese Patent Laid-Open No. 11-086823 JP 2006-236605 A JP 2007-157678 A Japanese Patent No. 3895645 JP-A-11-162436

  The present invention has been made on the basis of the above circumstances, and its purpose is that when sufficient airtightness is obtained in a normal use state, and gas is generated inside the exterior body of the laminated exterior electricity storage device. An object of the present invention is to provide a safety mechanism for a laminated exterior power storage device that can reliably discharge the gas from a specific part.

The safety mechanism of the laminated exterior power storage device of the present invention includes an exterior body in which exterior films stacked on each other are airtightly joined to each other at joint portions formed on the respective outer peripheral edges. A safety mechanism for a laminated exterior power storage device configured by storing an electrical storage device element and an electrolytic solution in a storage portion formed inside,
The outer surface of at least one of the exterior films is provided with a needle-like member that is fixed to a joint portion of the exterior film and arranged so that at least one end portion is located at a portion other than the joint portion.

In the safety mechanism of the laminated exterior power storage device of the present invention, both end portions of the needle-like member may be arranged so as to be located at portions other than the joint portion in the exterior film.
Further, in the safety mechanism of the laminated exterior power storage device of the present invention, a non-joined portion that is surrounded by the joint portion of the exterior film and communicates with the housing portion of the exterior body is formed on each outer peripheral edge portion of the exterior film. It is preferable that at least one end portion of the needle-like member is disposed so as to be located at the non-joined portion.
In such a safety mechanism of the laminated exterior power storage device, it is preferable that the joining portion has a projecting portion projecting to the non-joined portion, and the needle-like member is fixed to the projecting portion of the joining portion. .
Moreover, in the safety mechanism of the laminate-cased electricity storage device of the present invention, a plurality of the needle-like members may be provided.
In the safety mechanism of the laminated exterior power storage device of the present invention, the exterior film is pierced by the needle-like member as the internal pressure of the exterior body increases, whereby a gas discharge hole is formed in the exterior film.

In the safety mechanism of the laminated film exterior power storage device of the present invention, when gas is generated in the housing portion in which the electrical storage device is housed in the exterior body, the exterior body expands due to an increase in internal pressure of the exterior body. Thus, since no hole for exhausting gas is formed in any of the two exterior films constituting the exterior body, sufficient airtightness can be obtained in a normal use state. On the outer surface of at least one exterior film of the film, a needle-like member arranged so that one end is located at a portion other than the joint portion in the exterior film is fixed to the joint portion of the exterior film. When the gas is generated and the exterior body expands, one end of the needle-like member pierces and punctures the exterior film, thereby forming a gas discharge hole in the exterior film. To be discharged.
Therefore, according to the safety mechanism of the laminated exterior power storage device of the present invention, the exterior film does not have the gas discharge holes formed in the conventional safety mechanism, and therefore has sufficient airtightness in a normal use state. In addition, when gas is generated inside the exterior body, when the interior expands with an increase in internal pressure due to the generation of the gas, a specific shape of the exterior film can be obtained at a relatively low internal pressure by the needle-like member. Since the gas discharge hole is formed in the part, the generated gas can be reliably discharged to the outside from the gas discharge hole.

It is an explanatory top view which shows the structure of an example of the laminated exterior electrical storage device provided with the safety mechanism of this invention. It is explanatory drawing which expands and shows the safety mechanism of the lamination | stacking exterior | packing electrical storage device of FIG. It is sectional drawing for description which cuts and shows AA of the safety mechanism of the lamination | stacking exterior | packing electrical storage device of FIG. It is sectional drawing for description which cut | disconnects and shows BB of the safety mechanism of the laminated | stacked exterior electrical storage device of FIG. It is explanatory drawing which shows the structure of an example of an electrical storage device element. It is sectional drawing for description which shows the state which the non-joining site | part of the upper exterior film and the lower exterior film expanded. It is explanatory drawing which shows the state by which the gas exhaust hole was formed in the non-joining site | part of an upper exterior film and a lower exterior film. It is explanatory drawing which shows the modification of a safety mechanism. It is an exploded view for explanation showing the configuration of an example of a laminated exterior power storage device provided with a conventional safety mechanism.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is an explanatory plan view showing a configuration of an example of a laminated exterior power storage device provided with the safety mechanism of the present invention, and FIG. 2 is an enlarged view showing a safety mechanism of the laminated exterior power storage device of FIG. FIG. 3 is a cross-sectional view for explaining the safety mechanism AA of the laminated exterior power storage device of FIG. 2, and FIG. 4 is a sectional view of BB of the safety mechanism of the laminate exterior power storage device of FIG. FIG. It is.
In this laminated exterior power storage device 10, the exterior body 20 has a rectangular upper exterior film 21 </ b> A and a lower exterior film 21 </ b> B each having heat-bonding properties, and is overlapped with each other over the entire circumference of each outer peripheral edge portion. The formed joint 22 is hermetically joined to each other. A housing portion 23 having a rectangular planar shape in which the electricity storage device element is accommodated is formed in the exterior body 20, and the electricity storage device element is accommodated together with the organic electrolyte in the accommodation portion 23.
In the example shown in the drawing, the portion of the upper exterior film 21 </ b> A that forms the accommodating portion 23 is drawn.

On the outer peripheral edge of the upper exterior film 21A and the lower exterior film 21B in the exterior body 20, a non-joined portion 24 is formed in which one side communicates with the housing portion 23 and the other side is surrounded by the joint portion 22. The joining portion 22 has a projecting portion 22 a formed so as to project from the one side surrounding the non-joined portion 24 to the non-joined portion 24.
Needle-like members 25 are provided on the outer surfaces of the upper exterior film 21A and the lower exterior film 21B. Specifically, each of the needle-like members 25 is arranged in parallel to one side surrounding the non-joined portion 24 in the joint portion 22, and each central portion 25 a of the needle-like member 25 has the upper exterior film 21 </ b> A. And it is located in the protrusion part 22a of the junction part 22 of the lower exterior film 21B, is fixed by the clip 30, and each of the one end part 25b and the other end part 25c is located in the non-joining site | part 24.

As the upper exterior film 21A and the lower exterior film 21B constituting the exterior body 20, for example, a film in which a polypropylene (hereinafter referred to as “PP”) layer, an aluminum layer, a nylon layer, and the like are laminated in this order from the inside is suitable. Can be used.
When using, for example, a laminate of a PP layer, an aluminum layer and a nylon layer as the upper exterior film 21A and the lower exterior film 21B, the thickness is usually 50 to 300 μm.
The vertical and horizontal dimensions of the upper exterior film 21A and the lower exterior film 21B are appropriately selected according to the dimensions of the electricity storage device 11 accommodated in the accommodating portion 23. For example, the longitudinal dimension is 40 to 200 mm, and the lateral dimension is The dimension is 60 to 300 mm.
Moreover, the junction width of the junction part 22 of 21 A of upper exterior films and the lower exterior film 21B is 2-15 mm, for example.

As a material constituting the needle-like member 25, a metal material such as stainless steel, copper, or titanium, a ceramic material, a hard resin material, or the like can be used.
The total length of the needle-like member 25 is, for example, 5 to 100 mm, preferably 10 to 80 mm, although it depends on the dimensions of each part of the upper exterior film 21A.
Further, the length R1 of the central portion 25a located at the joint portion 22 in the needle-like member 25 is, for example, 1 mm or more, preferably 3 mm or more, and the one end portion 25b and the other end portion 25c located at the non-joint portion 24. The lengths R2 and R3 are, for example, 1 to 30 mm, preferably 2 to 10 mm, respectively.
The diameter of the needle-like member 25 is 0.1 to 3 mm, preferably 0.2 to 2 mm.
Moreover, the separation distance D between the needle-like member 25 and one side of the joint portion 22 is, for example, 1 to 30 mm, preferably 2 to 10 mm.

As shown in FIG. 5, the power storage device element 11 constituting the laminate-clad power storage device 10 includes a plurality of positive electrode plates each having a positive electrode layer 12 formed on a positive electrode current collector 12 a via a separator S, respectively. A negative electrode current collector 13a has an electrode laminate 11a formed by alternately laminating a plurality of negative electrode plates each having a negative electrode layer 13 formed thereon. On the upper surface of the electrode laminate 11a, lithium ion ions are formed. A lithium metal (lithium electrode layer) 18 as a supply source is disposed, and a lithium electrode current collector 18 a is laminated on the lithium metal 18. Reference numeral 19 denotes a lithium electrode extraction member.
Each of the plurality of positive electrode plates is electrically connected to a common positive electrode lead member, for example, aluminum positive electrode power supply tab 14 via a take-out member 16. On the other hand, each of the plurality of negative electrode plates is electrically connected to a common negative electrode lead member 15, for example, a copper negative electrode power supply tab 15 via a take-out member 17.
Each of the positive electrode power supply tab 14 and the negative electrode power supply tab 15 is drawn out from one end and the other end of the exterior body 20 so as to protrude to the outside.

As the positive electrode layer 12 constituting the electricity storage device element 11, an electrode material formed by adding a conductive material (for example, activated carbon, carbon black, etc.) and a binder as necessary is used. As an electrode material constituting the cathode 12, lithium reversibly carrying possible, but are not limited to, for _{example, LiCoO 2, LiNiO 2, LiFeO} 2 or the like of the general formula: Li _x M _y O _z (where M represents a metal atom, and x, y, and z are integers.) Cathode active materials such as metal oxides, activated carbon and the like.
Moreover, as the negative electrode layer 13 which comprises the electrical storage device element 11, what shape | molded the electrode material with the binder is used. The electrode material of the negative electrode layer 13 is not particularly limited as long as it can reversibly carry lithium. For example, powder, granular materials such as graphite, various carbon materials, polyacene-based substances, tin oxide, and silicon acid compounds, and granular form And negative electrode active materials.

Further, as the electrolytic solution, it is preferable to use an electrolyte in which an electrolyte is dissolved in an appropriate organic solvent. Specific examples of the organic solvent include aprotic organic solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, acetonitrile, and dimethoxyethane. These may be used alone or in combination of two or more. it can. As the electrolyte, which can produce lithium ion is used, and specific examples _{thereof, LiI, LiCIO 4, LiAsF 4} , LiBF 4, etc. LiPF ₆ and the like.

Such a laminated exterior electricity storage device 10 can be manufactured as follows, for example.
The electricity storage device element 11 is disposed at a position to be the accommodating portion 23 on the lower exterior film 21B, and the upper exterior film 21A is overlaid on the electricity storage device element 11, and in this state, the upper exterior film 21A and the lower exterior film 21B are overlapped. The three sides of the outer peripheral edge of each are heat-sealed. Thereby, the junction part 22 is formed in three sides in the outer periphery part of 21 A of upper exterior films, and the lower exterior film 21B.
Next, by injecting an electrolyte between the upper exterior film 21A and the lower exterior film 21B, and further thermally fusing one side of the outer periphery of the upper exterior film 21A and the lower exterior film 21B, The exterior body 20 is formed.
Then, the laminated exterior electricity storage device provided with a safety mechanism by disposing the needle-like member 25 at a required position on the outer surface of the upper exterior film 21A and the lower exterior film 21B constituting the exterior body 20 and fixing it with the clip 30. 10 is obtained.

In the safety mechanism of the laminated film exterior power storage device 10 described above, when gas is generated in the housing portion 23 in which the electrical storage dehigh element in the exterior body 20 is accommodated, the internal pressure of the exterior body 20 increases, 20 expands. Here, since the gas generated in the housing portion 23 enters the non-bonded portion 24 formed in the outer peripheral edge portion, not only the housing portion 23 of the exterior body 20 but also the upper exterior as shown in FIG. The non-bonded portion 24 of the film 21A and the lower exterior film 21B also expands. Thus, since no hole for discharging gas is formed in any of the upper exterior film 21A and the lower exterior film 21B constituting the exterior body 20, sufficient airtightness can be obtained in a normal use state. The needles are arranged on the outer surface of each of the upper exterior film 21A and the lower exterior film 21B so that each of the one end 25b and the other end 25c is located at the non-bonded portion 24 in the upper exterior film 21A and the lower exterior film 21B. Since the member 25 is fixed to the protruding portion 22a at the joint portion 22 between the upper exterior film 21A and the lower exterior film 21B, as shown in FIG. 7, the non-joined portion 24 between the upper exterior film 21A and the lower exterior film 21B. Is further expanded, one of the one end 25b and the other end 25c of the needle-like member 25 One or both of them pierce and perforate the upper exterior film 21A or the lower exterior film 21B, thereby forming a gas discharge hole 27 in the upper exterior film 21A or the lower exterior film 21B. As a result, the gas in the exterior body 20 is It is discharged outside.
Therefore, according to the safety mechanism of the laminated exterior power storage device 10, since the gas discharge hole formed in the conventional safety mechanism is not formed, sufficient airtightness can be obtained in a normal use state. When gas is generated inside the exterior body 20 and the inside expands with an increase in internal pressure due to the generation of the gas, a gas discharge hole is formed in a specific portion of the lower exterior film 21B with a relatively low internal pressure. 27 is formed, the generated gas can be reliably discharged to the outside from the gas discharge hole 27.

  The safety mechanism of the laminated film-clad electricity storage device of the present invention having such a configuration is applicable to the laminated film-clad electricity storage device which is an organic electrolyte battery in addition to an organic electrolyte capacitor such as a lithium ion capacitor. However, the organic electrolyte capacitor has a smaller charge capacity than the organic electrolyte battery but can be charged and discharged instantly. This is effective when the exterior power storage device is made of an organic electrolyte capacitor.

As described above, the embodiment of the safety mechanism of the laminated exterior power storage device of the present invention has been described. However, the present invention is not limited to the above embodiment, and various modifications can be made.
For example, as shown in FIG. 8, the needle-like member 25 has one end portion 25 b (or the other end portion 25 c) positioned at the non-bonded portion 24 and the other portion positioned at the bonded portion 22 and fixed by the clip 30. It may be. In such a configuration, the length R2 of the one end portion 25b (or the other end portion 25c) located at the non-joining portion 24 in the needle-like member 25 is, for example, 1 to 30 mm, preferably 2 to 10 mm. The length of the other part fixed to the part 22 is, for example, 1 mm or more, preferably 3 mm or more.
Further, the needle-like member 25 may be provided only on one of the upper exterior film 21A and the lower exterior film 21B.
In addition, the means for fixing the needle-like member 25 is not limited to the clip 30, and an appropriate fixing means, for example, a fixing member such as a tape can be used.

DESCRIPTION OF SYMBOLS 10 Laminated exterior electrical storage device 11 Electrical storage device element 11a Electrode laminated body 12 Positive electrode layer 12a Positive electrode collector 13 Negative electrode layer 13a Negative electrode collector 14 Positive electrode power supply tab 15 Negative electrode power supply tabs 16 and 17 Extraction member 18 Lithium metal (lithium electrode) layer)
18a Lithium electrode current collector 19 Lithium electrode take-out member 20 Exterior body 21A Upper exterior film 21B Lower exterior film 22 Joint part 22a Projection part 23 Storage part 24 Non-joint part 25 Needle-like member 25a Central part 25b One end part 25c Other end part 27 Gas discharge hole 30 Clip 50 Laminate exterior power storage device 51A Upper exterior film 51B Lower exterior film 52 Joint portion 53 Weak joint portion 55 Power storage device element 56 Power supply tab 57 for positive electrode Power supply tab for negative electrode S Separator

Claims (6)

The exterior films stacked on each other have exterior bodies that are airtightly joined to each other at the joints formed on the respective outer peripheral edges, and the storage device element and the storage device formed in the interior of the exterior body It is a safety mechanism of a laminated exterior power storage device configured to contain an electrolyte solution,
A laminate characterized in that an outer surface of at least one exterior film is provided with a needle-like member that is fixed to a joint portion of the exterior film and arranged so that at least one end portion is located at a portion other than the joint portion. Safety mechanism for external power storage devices.   The safety mechanism for a laminated exterior power storage device according to claim 1, wherein both end portions of the needle-like member are disposed so as to be located in a portion other than the joint portion in the exterior film.   A non-joined portion that is surrounded by a joint portion of the exterior film and communicates with a housing portion of the exterior body is formed on each outer peripheral edge portion of the exterior film, and at least one end portion of the needle-like member is the non-joint The safety mechanism for a laminated exterior power storage device according to claim 1, wherein the safety mechanism is disposed so as to be located at a bonding site.   4. The laminated exterior electricity storage device according to claim 3, wherein the joint portion has a projecting portion projecting to the non-joined portion, and the needle-like member is fixed to the projecting portion of the joint portion. Safety mechanism.   The safety mechanism for a laminated exterior electricity storage device according to claim 1, wherein a plurality of the needle-like members are provided.   The laminate according to any one of claims 1 to 5, wherein a gas discharge hole is formed in the exterior film by perforating the exterior film with the acicular member as the internal pressure of the exterior body increases. Safety mechanism for external power storage devices.

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