JP2014123699A - Electric storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric storage device having high safety by suppressing excessive heat generation of an electric storage device element caused by local concentration of a current flowing therein when the electric storage device element and the inside of a housing are highly heated.SOLUTION: An electric storage device includes: a housing; an electric storage device element stored in the housing and in which positive electrodes and negative electrodes are laminated via separators; an electrolyte stored in the housing; and a positive electrode terminal and a negative electrode terminal electrically connected to the positive electrodes and the negative electrodes constituting the electric storage device in the housing, and provided so as to project from the housing to the outside. The electric storage device element is provided with an insulating first fixing member for fixing the positive electrodes, the negative electrodes and the separators constituting the electric storage device element, and unfixing them at a temperature of 90°C or more and 160°C or less.

Description

  The present invention relates to an electricity storage device.

  In recent years, power storage devices such as secondary batteries, lithium ion capacitors, and electric double layer capacitors in which the power storage device element is housed in the exterior together with the electrolyte have been used as power sources for portable devices and electric vehicles for high output applications. It has been.

Such an electricity storage device includes an electricity storage device element in which a positive electrode and a negative electrode are overlapped via a separator, and the electricity storage device element having such a configuration is usually a tape or the like in order to maintain the desired overlap. (See, for example, Patent Document 1 and Patent Document 2).
Patent Document 1 includes an electrode winding body around which a laminated body in which a belt-like positive electrode and a negative electrode are stacked via a separator is wound as an electricity storage device element, and the outer peripheral surface of the electrode winding body is taped. A wound-type power storage device fixed in the above is disclosed. Further, the cited document 2 includes an electrode laminate in which a rectangular plate-like positive electrode and a negative electrode are laminated via a separator as a power storage device element, and the side surface of the electrode laminate is fixed with a tape. An electricity storage device is disclosed.

  In addition, the power storage device normally has an upper limit voltage, and is controlled so as not to exceed the upper limit voltage in combination with an appropriate protection circuit. However, when the protection circuit malfunctions and exceeds the upper limit voltage, the power storage device falls into an overcharged state, and the electrolyte and electrode material react to generate gas, which causes the internal pressure of the power storage device to increase. It rises and expands. For this reason, from the viewpoint of safety, the electricity storage device has a safety valve formed on the exterior body. When gas is generated in the electricity storage device, the safety valve is opened and the generated gas is released together with the electrolyte. The

However, in the stacked type electricity storage device, the fixing member for fixing the electrode laminate is made of a high heat resistant material such as polyimide. Even if the inside of the electrode laminate and the outer package becomes hot due to falling into an overcharged state, the fixed state is not removed and the fixed state is maintained. Therefore, before and after the gas and electrolyte are released from the safety valve, a short circuit occurs due to the deformation of the electrode at the fixing point by the fixing member, and heat is generated, and as a result, the vicinity of the fixing point of the electrode laminate different from the safety valve There is a problem that the exterior body opens.
In recent years, therefore, power storage devices such as lithium ion capacitors and electric double layer capacitors have been demanded to have high output and high capacity, and the power storage device itself or a module configuration in which a plurality of power storage devices are stacked is large. Opportunities to use current are increasing. For example, in a module in which a plurality of power storage devices are stacked, if one power storage device falls into an overcharged state, the other power storage devices function even after the safety valve opens and the gas is released together with the electrolyte. Therefore, a large current may continue to flow. Therefore, it may be overheated violently due to a short circuit at a location fixed by the fixing member of the electrode laminate. In particular, in a laminate-type lithium ion capacitor and an electric double layer capacitor having an exterior body in which laminate films are superposed on each other and a joint is formed at the outer peripheral edge portion, the fixing portion of the electrode laminate is excessively heated. As a result, the joint of the exterior body becomes soft and opens.

JP 2007-67097 A JP 2012-109125 A

  The present invention has been made on the basis of the above circumstances, and its purpose is that current is concentrated and flows locally when the inside of the electricity storage device element and the exterior body is heated. Thus, an object of the present invention is to provide an electricity storage device that can suppress excessive heat generation of the electricity storage device element and thus has high safety.

In the electricity storage device of the present invention, an electricity storage device element in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween and an electrolytic solution are accommodated in the exterior body, and each of the interior of the exterior body constitutes the electricity storage device. An electrical storage device comprising a positive electrode terminal and a negative electrode terminal that are electrically connected to the positive electrode and the negative electrode, and are provided so as to protrude outward from the exterior body,
The electrical storage device element is provided with an insulating first fixing member that fixes the positive electrode, the negative electrode, and the separator that constitute the electrical storage device element and that is unfixed at a temperature of 90 ° C. or higher and 160 ° C. or lower. Features.

  In the electricity storage device of the present invention, the first fixing member is preferably made of a meltable material having a melting point of 90 ° C. or higher and 160 ° C. or lower.

  In the electricity storage device of the present invention, it is preferable that the first fixing member has a tape shape and is arranged so as to extend in the stacking direction of the positive electrode, the negative electrode, and the separator in the electricity storage device element.

  In the electricity storage device of the present invention, the meltable material is preferably made of at least one thermoplastic resin selected from polyethylene and polypropylene.

  In the electricity storage device of the present invention, it is preferable that at least one of an intermittent cut portion and a notch portion is provided in the first fixing member.

In the electricity storage device of the present invention, the positive electrode terminal and the negative electrode terminal protrude in a direction perpendicular to the stacking direction of the positive electrode, the negative electrode, and the separator in the electricity storage device element,
The power storage device element is provided with an insulating second fixing member that can fix the positive electrode, the negative electrode, and the separator constituting the power storage device element even after the solid from the first fixing member is removed. And
The second fixing member is preferably disposed on a side surface of the power storage device element in a direction intersecting with a protruding direction of the positive electrode terminal or the negative electrode terminal.

In the electricity storage device of the present invention, the positive electrode terminal and the negative electrode terminal protrude in a direction perpendicular to the stacking direction of the positive electrode, the negative electrode, and the separator in the electricity storage device element,
It is preferable that the first fixing member is disposed on a side surface of the electricity storage device element in a direction along a protruding direction of the positive electrode terminal or the negative electrode terminal.

  The electricity storage device of the present invention is preferably charged and discharged with a current of 50 A or more.

  The electricity storage device of the present invention is preferably a lithium ion capacitor.

  In the electricity storage device of the present invention, the first fixing member has a function of releasing the fixing to the positive electrode, the negative electrode, and the separator at a specific temperature in the temperature range of 90 ° C. or higher and 160 ° C. or lower. Therefore, for example, when the battery is overcharged or exposed to a high temperature, the inside of the electricity storage device element and the exterior body becomes hot, and the positive electrode and the negative electrode are thermally expanded. Even when the electric current concentrates and flows in the place and the electricity storage device element generates heat, the fixing member is released when the temperature of the fixing member exceeds a specific temperature, and the positive electrode and the negative electrode are separated from each other. As a result, the resistance between the electrodes increases and the energization current in the electricity storage device decreases, or the energization current is interrupted, causing the current to flow in a fixed location by the fixing member in the electricity storage device element. Thus, since it is possible to suppress excessive heat generation of the electricity storage device element, high safety can be obtained.

It is an explanatory top view which shows an example of a structure of the electrical storage device of this invention. It is AA sectional drawing of the electrical storage device of FIG. It is BB sectional drawing of the electrical storage device of FIG. FIG. 2 is an explanatory perspective view showing an outline of an electrode laminate that constitutes an electricity storage device element in the electricity storage device of FIG. 1. (A1)-(a4) is explanatory drawing which shows the form of the intermittent notch part in a 1st fixing member, (b1)-(b3) is description which shows the form of the notch part in a 1st fixing member. FIG. It is an explanatory perspective view showing the outline of the electrode layered product which constitutes the electrical storage device element in other examples of the composition of the electrical storage device of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail.

FIG. 1 is an explanatory plan view showing an example of the configuration of the electricity storage device of the present invention, FIG. 2 is a cross-sectional view of the electricity storage device of FIG. 1 along AA, and FIG. FIG. 4 is a cross-sectional view taken along the line B-B, and FIG. 4 is a perspective view for explaining the outline of the electrode stack constituting the power storage device element in the power storage device of FIG. 1.
In this electricity storage device 10, the outer package 20 is formed over the entire circumference of each outer peripheral edge in a state in which the rectangular upper outer film 21 </ b> A and the lower outer film 21 </ b> B each having heat fusion properties are overlapped with each other. The joined portion 22 is hermetically joined to each other. A housing part 23 for housing the electricity storage device element 11 is formed inside the exterior body 20, and the electricity storage device element 11 is housed in the accommodation part 23 together with the electrolytic solution.
In the example shown in the drawing, a drawing process is applied to a portion of the upper exterior film 21 </ b> A that forms the accommodating portion 23.

  A rectangular positive electrode terminal 14 is provided on one side (left side in FIGS. 1 and 3) 22 a of the joint portion 22 of the outer package 20, and one end of the positive electrode terminal 14 is inside the outer package 20 within the power storage device element. 11 is electrically connected to the positive electrode current collector 12a, and the other end protrudes from one side 22a of the joint portion 22 to the outside. On the other hand, a rectangular negative electrode terminal 15 is provided on the other side (right side in FIGS. 1 and 3) 22b of the joint portion 22 of the outer package 20 opposite to the one side 22a, and one end of the negative electrode terminal 15 has an outer package. The body 20 is electrically connected to the negative electrode current collector 13 a of the electricity storage device element 11, and the other end protrudes outside from the other side 22 b of the joint portion 22.

A safety valve 25 is provided at the joint 22 of the exterior body 20.
The safety valve 25 is formed in an annular seal portion 26 in which a part of the upper exterior film 21 </ b> A and the lower exterior film 21 </ b> B are joined to each other at a non-joined portion 24 in the joint portion 22, and a central position of the seal portion 26. In addition, it is configured with a hole portion 27 penetrating the upper exterior film 21A.
Here, at least one safety valve 25 may be formed, but a plurality of safety valves may be formed.

As the upper exterior film 21A and the lower exterior film 21B constituting the exterior body 20, for example, a laminate 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.
For example, when a laminated body in which a PP layer, an aluminum layer, and a nylon layer are laminated is used 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 21 </ b> A and the lower exterior film 21 </ b> B are appropriately selected according to the dimensions of the electricity storage device element 11 accommodated in the accommodating portion 23, but the longitudinal dimension is, for example, 40 to 200 mm, The dimension is 60 to 300 mm.
Moreover, the junction width of the junction part 22 in the exterior body 20 is 2-15 mm, for example.
Although the dimension of the non-joining part 24 depends on the dimensions of the joining part 22 and the accommodating part 23, the dimension of one side communicating with the accommodating part 23 is 1 to 40 mm, and the dimension of the other side in contact with this one side is 3 to 12 mm. is there.

As shown in FIGS. 2 to 4, the power storage device element 11 that constitutes the power storage device 10 includes a plurality of plate-like positive electrodes and a plurality of plate-like negative electrodes that are alternately stacked via rectangular separators S. It has a substantially rectangular parallelepiped electrode laminate. Each of the plurality of positive electrodes constituting the electrode laminate is formed by forming the positive electrode layer 12 on a part of the rectangular positive electrode current collector 12a through a conductive layer as necessary. Each of the plurality of negative electrodes is formed by forming the negative electrode layer 13 on a part of the rectangular negative electrode current collector 13a through a conductive layer as necessary.
A lithium electrode 18 as a lithium ion supply source is disposed on the upper surface of the electrode stack, and a lithium electrode current collector 18a and a separator S are stacked on the lithium electrode 18 in this order. Reference numeral 19 denotes a lithium electrode extraction member.
In the positive electrode current collector 12a in each of the plurality of positive electrodes, extraction portions 16 are formed in regions where the positive electrode layer 12 is not formed, and these extraction portions 16 are welded to the positive electrode terminal 14 to each other. Electrically connected. The extraction portion 16 is formed on the side surface 11c of the four side surfaces 11c, 11d, 11e, and 11f of the electrode stack. On the other hand, the negative electrode current collector 13a in each of the plurality of negative electrodes is provided with a take-out portion 17 in a region where the negative electrode layer 13 is not formed, and is welded to each other to be electrically connected to the negative electrode terminal 15. ing. The extraction portion 17 is formed on the side surface 11e facing the side surface 11c in the electrode stack. Further, the positive electrode terminal 14 and the negative electrode terminal 15 connected to each of the extraction portions 16 and 17 are disposed so as to protrude in opposite directions toward the direction perpendicular to the side surfaces 11c and 11e of the electrode laminate.

Further, in the region where the positive electrode layer 12 of the positive electrode current collector 12a is not formed and the region where the negative electrode layer 13 of the negative electrode current collector 13a is not formed, an insulating material such as an acrylic resin, a fluororesin, or a polyimide is used. An insulating layer may be formed.
According to the insulating layer formed on the positive electrode current collector 12a and the negative electrode current collector 13a, gas is generated in the electricity storage device 10 or the electricity storage device element 11 generates heat, whereby the electricity storage device 10 is When expanded, the electrode stack is bent so as to wave, and even if the end of the positive electrode and the end of the negative electrode are in contact with each other, a short circuit between the positive electrode and the negative electrode can be prevented. Long life can be achieved.
This insulating layer is formed in other constituent members (for example, the positive electrode terminal 14 and the negative electrode) in a region where the positive electrode layer 12 of the positive electrode current collector 12a is not formed and a region where the negative electrode layer 13 of the negative electrode current collector 13a is not formed. It is preferable to be provided at a portion other than the joint portion with the terminal 15 or the like.
The insulating layer is formed by, for example, applying a sheet made of an insulating material to the positive electrode current collector 12a and the negative electrode current collector 13a, applying an insulating material liquid, or spraying the insulating material liquid with a spray or the like. It can be formed by the technique to do.

As the positive electrode layer 12, an electrode material formed by adding a conductive material (for example, activated carbon, carbon black, etc.) and a binder as necessary is used. Although it will not specifically limit as an electrode material which comprises the positive electrode layer 12 if lithium can be reversibly carry | supported, For example, activated carbon etc. are mentioned.
Moreover, as the negative electrode layer 13, what formed the electrode material with the binder is used. The electrode material constituting the negative electrode layer 13 is not particularly limited as long as it can reversibly carry lithium. For example, graphite, various carbon materials (for example, non-graphitizable carbon), polyacene-based material, tin oxide, etc. And powdered and granular negative electrode active materials such as silicon acid compounds.

As the separator S, cellulose (paper), cellulose / rayon composite material, polyethylene, polypropylene, and other known materials can be used.
Among these, a cellulose / rayon composite material is preferable in terms of durability and economy.
Although the thickness of the separator S is not specifically limited, Usually, about 10-50 micrometers is preferable.

The positive electrode current collector 12a and the negative electrode current collector 13a (hereinafter also referred to as “electrode current collector”) are made of a porous material having holes penetrating the front and back surfaces.
Examples of the form of the porous material constituting the electrode current collector include an expanded metal, a punching metal, a metal net, a foam, or a porous foil having through holes formed by etching.
The shape of the hole of the electrode current collector can be set to a circular shape, a rectangular shape, a polygonal shape, or any other appropriate shape.
Moreover, it is preferable that the thickness of an electrode electrical power collector is 5-50 micrometers from a viewpoint of intensity | strength and weight reduction.

The aperture ratio of the electrode current collector is usually 10 to 79%, preferably 20 to 60%.
Here, the aperture ratio is calculated by the following mathematical formula (1).

Formula (1):
Opening ratio (%) = [1− (mass of electrode current collector / true specific gravity of electrode current collector) / (apparent volume of electrode current collector)] × 100

  By using such a porous material as an electrode current collector, lithium ions released from the lithium electrode 18 as a lithium ion supply source can freely move between the electrodes through the holes of the electrode current collector. The negative electrode layer 13 and the positive electrode layer 12 in the negative electrode and / or the positive electrode can be doped with lithium ions.

As the material of the electrode current collector, various materials generally used for applications such as organic electrolyte batteries can be used.
Specific examples of the material of the negative electrode current collector 13a include stainless steel, copper, nickel, and the like. Specific examples of the material of the positive electrode current collector 12a include aluminum and stainless steel.

In addition, the power storage device element 11 is provided with an insulating first fixing member 30 that fixes the constituent members of the electrode stack (specifically, the positive electrode, the negative electrode, and the separator S constituting the power storage device element 11). Yes.
As shown in FIGS. 2 to 4, the first fixing member 30 has a tape shape (band shape), and the electrode is disposed on the side surface of the electrode stack so that the constituent members of the electrode stack can be fixed. It arrange | positions so that it may extend in the lamination direction of a laminated body.
In the example of this figure, the power storage device element 11 is provided with a plurality of (specifically, six) first fixing members 30. Each of the plurality of first fixing members 30 has one end portion 30a positioned on the outer peripheral edge portion of the upper surface (upper surface in FIG. 4) 11a of the electrode laminate, and the other end portion 30b of the electrode laminate. Located on the outer peripheral edge portion of the lower surface (lower surface in FIG. 4) 11b and extends over the outer peripheral edge portion of the upper surface 11a of the electrode laminate, the side surfaces 11d and 11f, and the outer peripheral edge portions of the lower surface 11b, and the stacking direction of the electrode current collector Are arranged over three surfaces so that the cross-section of the is substantially U-shaped. In addition, the plurality of first fixing members 30 respectively include the outer peripheral edge portion of the upper surface 11a and the outer peripheral edge portion of the lower surface 11b, and the side surfaces 11d and 11f of the electrode laminate, the positive electrode side surface, the negative electrode side surface, and the separator. It is set as the state closely_contact | adhered to the side surface of S, and, thereby, the electrode laminated body is being fixed.

  Further, the arrangement position of the first fixing member 30 is capable of fixing the electrode stack, and for the electrical connection between the positive electrode terminal 14 and the negative electrode terminal 15 in the electricity storage device element 11 and the doping of lithium ions. As long as there is no hindrance, any of the four side surfaces 11c, 11d, 11e, and 11f constituting the electrode laminate may be used, but a short circuit due to deviation of the end portions of the electrode terminals is prevented. From the viewpoint, it is preferable that the positive electrode terminal 14 or the negative electrode terminal 15 is provided on the side surface in the direction along the protruding direction, specifically, on the side surfaces 11d and 11f orthogonal to the direction in which the extraction portions 16 and 17 extend. By disposing the first fixing member 30 at such a position, variations in the stacking direction of the constituent members in the electrode assembly can be suppressed.

And the 1st fixing member 30 has the fixation release function from which fixation with respect to an electrode laminated body is removed in the temperature of 90 to 160 degreeC.
Since the first fixing member 30 has a function of releasing the fixation, the power storage device 10 and the exterior body 20 are heated to a high temperature when the power storage device 10 is overcharged or exposed to a high temperature, for example. In this case, since the fixing by the first fixing member 30 is released, the constituent members of the electrode stack can be separated, and the positive electrode and the negative electrode can be separated in the stacking direction of the electrode stack.
In addition, since the first fixing member 30 is provided, the structure of the electrode stack can be obtained when the positive electrode terminal 14 and the negative electrode terminal 15 are electrically connected to the electrode stack in the process of manufacturing the electricity storage device element. Since it can suppress that a member varies, work efficiency goes up.

  In addition, as shown in FIGS. 2 to 4, the first fixing member 30 is disposed so as to extend over the outer peripheral edge portion, the side surface, and the outer peripheral edge portion of the lower surface 11 b of the electrode laminate. It is necessary that the ridge between the upper surface 11a and the side surface and the ridge between the lower surface 11b and the side surface have flexibility so that they can be bent.

As the first fixing member 30, a tape having an adhesive layer on one surface of a tape-like substrate can be used.
The first fixing member 30 may have a configuration in which a tape-like base material is fixed with an adhesive. Specifically, for example, one surface of the end portion of the tape-shaped substrate is fixed to the outer peripheral edge portion of the upper surface of the electrode laminate and the outer peripheral edge portion of the lower surface of the electrode laminate, respectively, with an adhesive, or A tape-shaped base material may be made around the electrode laminate, and ends of the base material may be fixed with an adhesive.

The base material constituting the first fixing member 30 has an insulating property, and has resistance to the constituent materials of the positive electrode layer 12, the negative electrode layer 13, and the conductive layer provided as necessary, as well as resistance to the electrolytic solution. And has a melting point of 90 ° C. or higher and 160 ° C. or lower (hereinafter also referred to as “specific melting material”).
Here, the melting point of the meltable material constituting the first fixing member 30 can be measured from an endothermic peak in differential scanning calorimetry (DSC).

  Since the base material constituting the first fixing member 30 is made of a specific meltable material, the first fixing member 30 is cut by melting at a specific temperature in a temperature range of 90 ° C. or higher and 160 ° C. or lower. As a result, the fixation is released.

  When the melting point of the material constituting the base material of the first fixing member 30 is less than 90 ° C., the base material cannot be melted during the operation of the electricity storage device 10 to maintain the shape. It becomes difficult to fix the laminate. For this reason, misalignment is likely to occur in the constituent members of the electrode laminate (specifically, the positive electrode, the negative electrode, and the separator S constituting the power storage device element 11), and thus the life of the power storage device is shortened by causing an internal short circuit. There is a fear. On the other hand, when the melting point of the material constituting the base material of the first fixing member 30 exceeds 160 ° C., the fixing does not come off even when the inside of the electricity storage device element 11 and the exterior body 20 becomes extremely hot, There is a risk that current will flow in a fixed location and heat will be generated excessively, so that sufficient safety cannot be obtained.

The specific melt material is preferably made of at least one thermoplastic resin selected from polyethylene and polypropylene.
Specific examples of the polyethylene constituting the specific meltable material include those having a weight average molecular weight (Mw) of 1,000 to 1,000,000.

  By using polyethylene and / or polypropylene as the specific meltable material, the base material can be made insulative, and the obtained first fixing member 30 is flexible and required resistance (specifically Specifically, resistance to the electrolytic solution and resistance to the constituent material of the positive electrode layer 12, the negative electrode layer 13, and the conductive layer provided as necessary are obtained. Moreover, the temperature at which the first fixing member 30 is melted can be made lower than the temperature at which a conventionally known film such as a laminate in which a PP layer, an aluminum layer, and a nylon layer are laminated, for example.

The adhesive constituting the adhesive layer of the first fixing member 30 has an insulating property and has resistance to the electrolyte solution, as well as the constituent material of the positive electrode layer 12, the negative electrode layer 13, and a conductive layer provided as necessary. Various materials can be used as long as they have resistance to the substrate and can adhere to the base material and electrode laminate constituting the first fixing member 30.
Specific examples of the adhesive include acrylic pressure-sensitive adhesives.

The adhesive constituting the first fixing member 30 is bonded to at least one of the base material and the electrode laminate by melting at a temperature of 90 ° C. or higher and 160 ° C. or lowering, for example, the adhesiveness is reduced. It is preferable that the state is released.
By using an adhesive whose adhesive state is released from at least one of the base material and the electrode laminate at a temperature of 90 ° C. or higher and 160 ° C. or lower, a more excellent fixing release function is obtained for the first fixing member 30. It is done.

Preferable specific examples of the first fixing member 30 are a polyethylene tape (melting point: 140 ° C.) and a polypropylene tape (melting point: 160 ° C.).
By using such polyethylene tape and polypropylene tape as the first fixing member 30, for example, a PP layer, an aluminum layer, and a nylon layer are laminated as the upper exterior film 21A and the lower exterior film 21B constituting the exterior body 20. When a conventionally known film such as a laminate is used, the temperature at which the first fixing member 30 is melted is lower than the temperature at which the exterior body film is melted. Therefore, even when the current is concentrated and flows to the fixed portion of the power storage device element 11 by the first fixing member 30 and the power storage device element 11 generates heat, before reaching the temperature at which the outer package 20 melts, Since the fixing to the electrode laminate by the first fixing member 30 is reliably removed, the exterior body 20 is not melted. Further, since the electricity storage device element 11 is a heat source, the joint portion of the outer package 20 does not open before the first fixing member 30 in close contact with the heat source melts and is unfixed.

The thickness of the first fixing member 30 is preferably 10 to 200 μm.
When the thickness of the solid first fixed member 30 is less than 10 μm, sufficient mechanical strength cannot be obtained for the first fixing member 30, and there is a possibility that breakage due to insufficient strength may occur. On the other hand, if the thickness of the first fixing member 30 exceeds 200 μm, sufficient flexibility cannot be obtained for the first fixing member 30 and it is difficult to bend the electrode laminate. May not be sufficiently fixed.

In addition, the first fixing member 30 has intermittent cut portions (perforations) as shown in FIGS. 5A1 to 5A4 and cuts as shown in FIGS. 5B1 to 5B3, for example. At least one of the notches may be provided.
Since at least one of the intermittent notch and the notch is provided, the first fixing member 30 is easily cleaved by heat or the like, so that the unlocking function is enhanced, and thus the power storage device 10 has higher safety. .
Here, the first fixing member 30 in FIG. 5A1 has an intermittent cut portion formed by a broken line-like cut 33a in which straight cuts are arranged in the width direction (short direction) of the first fixed member 30. Is formed. The first fixing member 30 shown in FIG. 5A2 has an intermittent cut portion formed by a broken line-like cut 33b in which circular cuts are arranged in the width direction (short direction) of the first fixed member 30. ing. In the first fixing member 30 in FIG. 5A3, an intermittent cut portion is formed which is formed by a broken line-like cut 33c in which rhombus cuts are arranged in the width direction (short direction) of the first fixed member 30. ing. In the first fixing member of FIG. 5 (a4), an intermittent cut portion is formed which is formed by a broken line-like cut 33d in which circular cuts are arranged in the length direction (longitudinal direction) of the first fixed member 30. Yes.
Further, in the first fixing member of FIG. 5 (b1), a cutout portion formed of a triangular notch 33e is formed on one side of the central portion in the length direction (longitudinal direction) of the first fixing member. Has been. The first fixing member shown in FIG. 5 (b2) has a notch formed by a linear cut 33f on one side of the central portion in the length direction (longitudinal direction) of the first fixing member. Yes. In the example of FIG. 5 (b2), the linear cut 33f is provided on one side, but the linear cut may be provided on the other side as well as on one side. In the first fixing member of FIG. 5 (b3), a notch portion formed of a rhombus cut 33g is formed in the central portion of the first fixing member.

As the electrolytic solution filled in the outer package 20, an organic electrolytic solution in which an electrolyte is dissolved in an appropriate organic solvent is preferably used.
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, LiCIO 4, LiBF 4, LiPF} 6, LiN (C 2 F 5 SO 2) 2, LiN (CF 3 SO 2) _2, etc. are mentioned, These can be used individually or in combination of 2 or more types.

Such an electricity storage device 10 can be manufactured as follows, for example.
First, a positive electrode and a negative electrode are laminated via a separator S, and the laminated body is fixed by the first fixing member 30 to obtain an electrode laminated body. Further, a lithium electrode 18 and a lithium electrode collection are obtained on the obtained electrode laminated body. The electrical storage device element 11 is produced by laminating the electric body 18a and the separator S in this order. Thereafter, the positive electrode terminal 14 and the negative electrode terminal 15 are connected to the electricity storage device element 11.
Next, the power storage device element 11 to which the positive electrode terminal 14 and the negative electrode terminal 15 are connected is disposed at a position to be the housing portion 23 on the lower exterior film 21 </ b> B, and the non-bonded portion 24 is to be at a position to be the non-bonded portion 24. A heat block having a shape conforming to the planar shape of the upper outer film 21A having a hole 27 is overlaid on the electricity storage device element 11, and the outer peripheral edges of the upper outer film 21A and the lower outer film 21B. Three sides of the part are heat-sealed.
And after inject | pouring electrolyte solution between 21 A of upper exterior films, and the lower exterior film 21B, an exterior body is carried out by heat-seal | bonding one side of the unsealed part in the outer periphery part of 21 A of upper exterior films, and the lower exterior film 21B By forming 20, the electricity storage device 10 is obtained.

  In the above electricity storage device 10, for example, when the battery is overcharged or exposed to a high temperature, the inside of the electricity storage device element 11 and the exterior body 20 becomes hot, so that the electrolytic solution and the electrode material react. Gas is generated, the internal pressure of the electricity storage device 10 is increased by this gas, and the exterior body 20 is expanded. In addition, since the first fixing member 30 for fixing the electrode stack is provided on the electricity storage device element 11, the positive electrode and the negative electrode are thermally expanded. The electric current concentrates and flows in the fixing portion by the one fixing member 30 and the electricity storage device element 11 generates heat.

Thus, since the exterior body 20 is provided with the safety valve 25, the exterior body 20 expands to open the safety valve 25, and the gas generated through the safety valve 25 is released together with the electrolytic solution.
Furthermore, the first fixing member 30 includes a base material made of a specific meltable material having a melting point in a temperature range of 90 ° C. or higher and 160 ° C. or lower, and has a temperature range of 90 ° C. or higher and 160 ° C. or lower. At a specific temperature, the first fixing member 30 is heated by heat generation of the electricity storage device element 11 because it has a fixing release function that releases the fixing to the positive electrode, the negative electrode, and the separator, and the first fixing member The fixation is removed when the temperature of 30 exceeds a specific temperature (melting point of the specific meltable material constituting the base material). And since the positive electrode, the negative electrode, and the separator S constituting the electrode laminate are separated and the positive electrode and the negative electrode are separated in the stacking direction of the electrode laminate, the electrolyte is released from the safety valve 25, The energizing current is interrupted by the absence of the electrolyte in the outer package 20.
Thus, according to the electricity storage device 10, the electricity storage device element 11 is prevented from excessively generating heat due to the current flowing in a concentrated manner at the location fixed by the first fixing member 30 in the electricity storage device element 11. Therefore, high safety can be obtained.

  Furthermore, the power storage device 10 can be suitably used as a power storage device device (module) including a plurality of power storage devices. In such an electricity storage device device, even if one of the plurality of electricity storage devices falls into an overcharged state and the inside of the electricity storage device element and the exterior body become hot and loses the electricity storage device function. Further, it is possible to suppress the excessive generation of heat by the power storage device that has lost its power storage device function (hereinafter also referred to as “function loss device”). Therefore, the safety of the power storage device device (module) is improved.

The electricity storage device of the present invention having such a configuration can be suitably applied as an organic electrolyte capacitor such as an electric double layer capacitor or a lithium ion capacitor, and is also suitable as an organic electrolyte battery such as a lithium ion secondary battery. Can be applied. Among these, since high output and high capacity are required and it is necessary to use a large current, it is applied to a capacitor that charges and discharges with a large current of 50 A or more, particularly a lithium ion capacitor. Is preferred.
And it is suitable for power use, especially for in-vehicle use.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various change can be added.
For example, as shown in FIG. 6, the power storage device element includes a side surface in a direction intersecting with a protruding direction of the positive electrode terminal or the negative electrode terminal in the power storage device element, specifically, four side surfaces 11 c constituting the electrode laminate. An insulating second fixing member 31 that fixes the constituent members of the electrode laminate together with the first fixing member 30 may be provided on at least one of the side surfaces 11c and 11e of 11d, 11e, and 11f. The second fixing member 31 has a function capable of fixing the positive electrode, the negative electrode, and the separator constituting the power storage device element even after the solid by the first fixing member 30 is removed.
By providing the second fixing member 31, even when the fixing by the first fixing member 30 is released, the deformation of the electrode laminate near the terminal is suppressed, and thus a short circuit occurs near the terminal. Therefore, high safety is obtained by the electricity storage device.
More specifically, as shown in FIG. 6, when the second fixing member 31 is provided on the side surfaces 11c and 11e of the electrode laminate, the first fixing member 30 is detached, thereby the second fixing member. The electrode laminate is bent so as to wave with the fixed portion 31 as a fulcrum. Therefore, in the central portion of the electrode current collector (portion where the positive electrode layer 12 and the negative electrode layer are stacked), the constituent members are separated from each other, but deformation near the second fixing member is suppressed. . As a result, the occurrence of an internal short circuit in the electricity storage device can be suppressed, and thus high safety can be obtained.
Further, as shown in FIG. 6, the second fixing member 31 is provided on the side surfaces 11c and 11e of the electrode laminate, and the first fixing member 30 is provided on the side surface 11b and / or the side surface 11b of the electrode laminate. If provided, the fixing by the first fixing member 30 is easily released.

In addition, when the second fixing member 31 is provided on the side surfaces 11c and 11e of the electrode stack as shown in FIG. 6, in the electrode stack, a region where the positive electrode layer of the positive electrode current collector is not formed, and It is preferable that an insulating layer is formed in a region where the negative electrode layer of the negative electrode current collector is not formed.
Since the insulating layer is formed on the electrode current collector, the electrode stack may wave when the electricity storage device expands due to the generation of gas or the electricity storage device element 11 generating heat in the electricity storage device. Even when the end of the positive electrode and the end of the negative electrode are in contact with each other, a short circuit between the positive electrode and the negative electrode can be prevented, so that the life of the electricity storage device can be extended. In addition, when the first fixing member 30 is detached and the electrode laminate is bent so as to be waved with the fixing portion by the second fixing member 31 as a deformation fulcrum, the end of the positive electrode and the end of the negative electrode Even when they are in contact with each other, a short circuit between the positive electrode and the negative electrode can be prevented, so that higher safety can be obtained by the power storage device.

Similar to the first fixing member 30, the second fixing member 31 is in the form of a tape (band), and the electrode laminated body is attached to the side surfaces 11c and 11e so that the constituent members of the electrode laminated body can be fixed. It arrange | positions so that it may extend in the lamination direction.
In the example of this figure, the 2nd fixing member 31 is provided in the electrical storage device element. Each of these two second fixing members 31 has one end portion 31a positioned at the outer peripheral edge portion of the upper surface 11a of the electrode laminate, and the other end portion 31b of the outer peripheral edge of the lower surface 11b of the electrode laminate body. And extends over the outer peripheral edge of the upper surface 11a of the electrode stack, the outer peripheral edges of the side surfaces 11c and 11e, and the lower surface 11b, so that the cross section in the stacking direction of the electrode current collector is substantially U-shaped. It is arranged over three surfaces. The second fixing member 31 includes a positive electrode side surface, a negative electrode side surface, and a separator that constitute the outer peripheral edge portion of the upper surface 11a and the outer peripheral edge portion of the lower surface 11b, and the side surfaces 11c and 11e, respectively. In this way, the electrode laminate is fixed.

As the second fixing member 31, a tape having an adhesive layer on one surface of a tape-like substrate can be used.
As the base material constituting the second fixing member 31, a heat-resistant material having a melting point exceeding 160 ° C. such as polyimide, polyphenylene sulfide, polyethylene terephthalate (PET), or the like can be suitably used. Further, a material used as the first fixing member such as polyethylene or polypropylene can be used.
As an adhesive constituting the adhesive layer, for example, an acrylic adhesive can be used.

  Specific examples of the present invention will be described below, but the present invention is not limited to these examples.

<Example 1>
(1) Production of positive electrode plate:
By forming a plurality of circular through-holes having an opening area of 0.79 mm ^{2 in} a zigzag pattern on a strip-like aluminum foil having a width of 200 mm and a thickness of 15 μm by a punching method, a current collector having an aperture ratio of 42% Was made. A conductive paint containing graphite as a conductive material is applied to a part of the current collector, using a vertical die type double-side coating machine, with a coating width of 130 mm and a target value of the coating thickness of both sides set to 20 μm. After coating on both sides, a conductive layer was formed on the front and back surfaces of the current collector by drying under reduced pressure at 200 ° C. for 24 hours.
Next, on the conductive layer formed on the front and back surfaces of the current collector, a positive electrode paint containing activated carbon as an electrode material is applied to a target value of 150 μm by using a vertical die type double-side coating machine. Then, after coating on both sides, a positive electrode layer was formed on the conductive layer by drying under reduced pressure at 200 ° C. for 24 hours.
The material obtained by laminating the conductive layer and the positive electrode layer on a part of the current collector thus obtained is referred to as a portion where the conductive layer and the positive electrode layer are laminated (hereinafter referred to as “coating part” for the positive electrode plate). ) Is 102 mm × 130 mm and cut into a size of 102 mm × 140 mm so that the portion where no layer is formed (hereinafter also referred to as “uncoated portion” for the positive electrode plate) is 102 mm × 10 mm. Thus, a positive electrode plate was produced.

(2) Production of negative electrode plate:
By forming a plurality of circular through holes having an opening area of 0.79 mm ^{2 in} a zigzag pattern on a strip-shaped copper foil having a width of 200 mm and a thickness of 10 μm by a punching method, a current collector having an aperture ratio of 42% Got. A part of this current collector is coated with a negative electrode paint containing non-graphitizable carbon as an electrode material, using a vertical die type double-side coating machine, with a coating width of 133 mm and a target value for the coating thickness of both sides of 80 μm. After carrying out double-sided coating, the negative electrode layer was formed on the front and back surfaces of the current collector by drying under reduced pressure at 200 ° C. for 24 hours.
The material in which the negative electrode layer is formed on a part of the current collector obtained in this way has a portion where the negative electrode layer is formed (hereinafter referred to as “coating part” for the negative electrode plate) of 105 mm × 133 mm. Then, the negative electrode plate was produced by cutting into a size of 105 mm × 143 mm so that a portion where the negative electrode layer was not formed (hereinafter referred to as “uncoated part” for the negative electrode plate) was 105 mm × 10 mm. .

(3) Production of electricity storage device element (lithium ion capacitor element):
First, 10 positive plates, 11 negative plates, and 22 separators of cellulose / rayon composite material having a thickness of 50 μm were prepared. The coated portions of the positive plate and the negative plate were overlapped, but the respective uncoated portions were coated. A separator, a negative electrode plate, a separator, and a positive electrode plate were stacked in this order so that the work part was on the opposite side. Then, four 10 mm (length) × 8 mm (width) × 50 μm (thickness) polyethylene tapes (melting point: 140 ° C.) are prepared, and the coated portion and the uncoated portion of the positive electrode plate in the rectangular parallelepiped laminate are prepared. Two polyethylene tapes are extended in the laminating direction of the laminate on each of two side faces (side faces 11d and 11f in FIG. 4) parallel to the alignment direction, and one end of the polyethylene tape is positioned at the outer peripheral edge of the upper surface of the laminate. And it stuck so that the other end part might be located in the outer-periphery edge part of the lower surface of a laminated body, and the electrode laminated body was produced by fixing a laminated body in this way.
Next, a 260 μm-thick lithium foil is cut, and the cut lithium foil is pressure-bonded to a 40 μm-thick lithium electrode current collector (copper lath) to produce a lithium electrode as a lithium ion supply source. The lithium electrode was disposed on the upper side of the electrode stack so as to face the negative electrode.
Subsequently, a sealant film was previously heat-sealed on the seal portion on each uncoated portion of the 10 positive electrode plates of the produced electrode laminate, and was made of aluminum having a width of 50 mm, a length of 50 mm, and a thickness of 0.2 mm. The connecting portion of the positive terminal was overlapped and ultrasonically welded. On the other hand, a sealant film was heat-sealed in advance to a seal portion on each of the uncoated portion and the lithium electrode of each of the 11 negative electrode plates of the electrode laminate, and had a width of 50 mm, a length of 50 mm, and a thickness of 0.2 mm. The connection part of the copper negative electrode terminal was overlapped and resistance welded. A lithium ion capacitor element (electric storage device element) was produced as described above.

(4) Production of lithium ion capacitor:
Based on the configuration shown in FIGS. 1 to 4, a lithium ion capacitor was manufactured as follows.
A PP layer, an aluminum layer, and a nylon layer are laminated, and the dimensions are 125 mm (vertical width) × 180 mm (horizontal width) × 150 μm (thickness), and 105 mm (vertical width) × 145 mm (horizontal width) in the central portion that serves as a housing portion. An upper exterior film that has been subjected to drawing (the width of the outer peripheral edge as a joint portion is 10 mm), a PP layer, an aluminum layer, and a nylon layer are laminated, and the dimensions are 125 mm (vertical width) × 180 mm (horizontal width) × 150 μm. A (thickness) lower exterior film was prepared, and a hole having a diameter d of 3 mm was formed on the outer peripheral edge of the upper exterior film.
Next, the lithium ion capacitor element is disposed at a position serving as a housing portion on the lower exterior film so that each of the positive electrode terminal and the negative electrode terminal protrudes outward from the end portion of the lower exterior film, and the lower exterior film A heat block having a shape that conforms to the planar shape of the non-joined part is disposed at a central position (position to be a non-joined part) on one side of the outer peripheral edge. Thereafter, an upper exterior film is overlaid on the lithium ion capacitor element, and three sides (two sides from which the positive terminal and the negative terminal protrude and one other side) at the outer peripheral edge of the upper exterior film and the lower exterior film are thermally melted. I wore it. Thereafter, a mixture obtained by dissolving LiPF ₆ at a concentration of 1.2 mol / L in a solvent in which propylene carbonate and diethyl carbonate are mixed at a ratio of 1: 2 as an organic electrolyte between the upper exterior film and the lower exterior film. After 50 g of the solution was injected and vacuum impregnated, the remaining one side was heat-sealed under reduced pressure and vacuum sealed to produce a lithium ion capacitor (S1).

(5) Safety confirmation test (overcharge test):
About the produced lithium ion capacitor (S1), the safety test was done with the following method. The results are shown in Table 1.
A voltage higher than the upper limit voltage is applied to the lithium ion capacitor (S1) to generate gas in the exterior body so that the safety valve is opened, and then a constant current at a charging voltage of 20V and a charging current of 200A. Constant voltage charging (CCCV charging) was performed for 60 seconds. After the completion of charging, the exterior of the exterior body was visually observed to confirm the presence or absence of openings in the region other than the safety valve of the exterior body (including peeling of the joint of the exterior body). Thereafter, the exterior body was further disassembled, and the state of the fixing member was visually confirmed.

<Example 2>
In Example 1, a lithium ion capacitor was obtained in the same manner as in Example 1 except that a 10 mm (length) × 8 mm (width) × 50 μm (thickness) polypropylene tape (melting point: 160 ° C.) was used as the fixing member. (S2) was obtained. A safety confirmation test was performed on the lithium ion capacitor (S2) by the same method as in Example 1. The results are shown in Table 1.

<Example 3>
A lithium ion capacitor (S3) having the same configuration as the lithium ion capacitor produced in Example 2 was produced. For this lithium ion capacitor (S3), in the safety confirmation test of Example 1, a safety confirmation test was performed by the same method as in Example 1 except that the charging current under the charging conditions was set to 50A. The results are shown in Table 1.

<Example 4>
In Example 2, as a fixing member, four polyimide tapes of 10 mm (length) × 8 mm (width) × 50 μm (thickness) are prepared together with four polypropylene tapes, and these polyimide tapes are laminated in a rectangular parallelepiped shape. Two in each of two side surfaces (side surfaces 11c and 11e in FIG. 4) orthogonal to the direction in which the coated portion and the uncoated portion of the positive electrode plate in the body are aligned, and extend in the stacking direction of the stack. Is the same as in Example 2 except that the electrode laminated body was manufactured by attaching the laminated body so that the other end portion was located on the outer peripheral edge portion of the lower surface of the laminated body. Thus, a lithium ion capacitor (S4) was obtained. A safety confirmation test was performed on this lithium ion capacitor (S4) by the same method as in Example 1 except that in the safety confirmation test of Example 1, the charging current under charging conditions was 250 A. The results are shown in Table 1.

<Example 5>
In Example 4, an acrylic resin liquid was applied so as to cover a region other than the connection portion of the positive electrode terminal in the uncoated portion of the positive electrode plate and a region other than the connection portion of the positive electrode terminal in the uncoated portion of the negative electrode plate, A lithium ion capacitor (S5) was obtained in the same manner as in Example 4 except that an insulating layer made of an acrylic resin was formed by drying the obtained coating film at a temperature of 100 ° C. A safety confirmation test was performed on the lithium ion capacitor (S5) by the same method as in Example 1 except that the charging current in the charging condition was set to 300 A in the safety confirmation test of Example 1. The results are shown in Table 1.

<Example 6>
In Example 2, the fixing member has a size of 10 mm (length) × 8 mm (width) × 50 μm (thickness), and linear cuts are formed at equal intervals of 0.5 mm in the center in the longitudinal direction. In the same manner as in Example 2 except that a polypropylene tape (melting point: 160 ° C.) in which intermittent cut portions formed by broken line cuts arranged in series in the width direction (short direction) were used, a lithium ion capacitor ( S6) was obtained. A safety confirmation test was performed on this lithium ion capacitor (S6) by the same method as in Example 1 except that in the safety confirmation test of Example 1, the charging current under charging conditions was 250 A. The results are shown in Table 1.

<Comparative example 1>
In Example 1, a lithium ion capacitor (C1) was obtained in the same manner as Example 1, except that a polyimide tape of 10 mm (length) × 8 mm (width) × 50 μm (thickness) was used as the fixing member. A safety confirmation test was performed on the lithium ion capacitor (C1) by the same method as in Example 1. The results are shown in Table 1.

<Comparative example 2>
In Example 1, Kapton (registered trademark) tape was used so as to cover a region other than the connection portion of the positive electrode terminal in the uncoated portion of the positive electrode plate and a region other than the connection portion of the positive electrode terminal in the uncoated portion of the negative electrode plate. Affixed to form an insulating layer, and has a dimension of 10 mm (length) × 8 mm (width) × 50 μm (thickness) as a fixing member, and extends in the short direction on both sides in the center in the longitudinal direction. A lithium ion capacitor (C2) was obtained in the same manner as in Example 1 except that a polyimide tape having a notch formed by a linear cut having a length of 1 mm was used. A safety confirmation test was performed on this lithium ion capacitor (C2) by the same method as in Example 1 except that in the safety confirmation test of Example 1, the charging current under charging conditions was 250 A. The results are shown in Table 1.

As is clear from the results in Table 1, the lithium ion capacitors according to Examples 1 to 3 were cut when the fixing member was melted at a temperature of 90 ° C. or higher and 160 ° C. or lower. It has a fixing release function for releasing the fixing to the electrode laminate at a temperature of from 0 ° C. to 160 ° C. Therefore, when charging was performed after the safety valve was opened, the electrode laminate was not fixed by the fixing member, and the electrodes were separated apart. In addition, since the electrodes are separated from each other, the resistance between the electrodes is increased, and thus the current flowing through the electricity storage device element is reduced. It was done.
Further, in the lithium ion capacitors according to Example 4 and Example 5, the fixing member disposed on the side surface in the direction along the protruding direction of the positive electrode terminal or the negative electrode terminal in the electricity storage device element is 90 ° C. or higher and 160 ° C. or lower. It is cut by melting at a temperature, and has a fixing release function that releases fixing to the electrode laminate at a temperature of 90 ° C. or higher and 160 ° C. or lower. On the other hand, the fixing member disposed on the side surface in the direction intersecting the protruding direction of the positive electrode terminal or the negative electrode terminal in the electricity storage device element has a fixing release function that releases the fixing to the electrode laminate at a temperature of 90 ° C. or higher and 160 ° C. or lower. It is not a thing. Therefore, when charging is performed after the safety valve is opened, the electrode laminated body is unfixed by the fixing member having the fixing release function, and this fixing member is obtained from the lithium ion capacitors of Examples 1 to 3. It was easy to come off. On the other hand, even when the fixing member having no fixing release function was heated to 250 ° C. or higher, the fixing to the electrode laminate was not released and the fixed state was maintained. In this way, the fixing member having the unlocking function is easily fixed, and the electrode stack is not separated in the central portion of the electrode stack, but a large current is generated after the safety valve is opened. Even if it flowed, the gas could be safely discharged. In particular, since the lithium ion capacitor according to Example 5 was provided with an insulating layer on the electrode current collector, gas could be safely discharged even when a larger current flowed.
Further, in the lithium ion capacitor according to Example 6, since the fixing member is formed with a broken line-like cut, the cut is likely to be caused by heat at the cut, and thus the electrode laminate can be fixed. It was confirmed that it was easy to come off. Therefore, the gas could be discharged more safely.
On the other hand, the lithium ion capacitor according to Comparative Example 1 does not have a fixing release function in which the fixing member is not fixed to the electrode laminate at a temperature of 90 ° C. or higher and 160 ° C. or lower. Therefore, when charging was performed after the safety valve was opened, even when heated to 250 ° C. or higher, fixation to the electrode laminate was not released, and the fixed state was maintained. As a result, it was confirmed that the current was concentrated and heated at the fixing portion of the electric storage device element by the fixing member, and the exterior body was peeled off by heat and an opening was formed by melting.
In addition, the lithium ion capacitor according to Comparative Example 2 does not have a fixing release function in which the fixing member is not fixed to the electrode laminate at a temperature of 90 ° C. or higher and 160 ° C. or lower, although the broken member is formed with a dashed cut. Absent. Therefore, when charging was performed after the safety valve was opened, it was confirmed that the portion where the incision was made was broken, and that the exterior body was peeled off by heat and an opening by melting was formed. It was. The reason for this is that a short circuit occurs in the electrode laminate before the location where the notch of the fixing member is provided breaks, and as a result, heat peeling occurs at the joint of the exterior body and an opening due to melting is formed. It is speculated that it was done.
From the above, it is clear that the lithium ion capacitors according to Examples 1 to 6 have high safety.

DESCRIPTION OF SYMBOLS 10 Power storage device 11 Power storage device element 11a Upper surface 11b Lower surface 11c, 11d, 11e, 11f Side surface 12 Positive electrode layer 12a Positive electrode collector 13 Negative electrode layer 13a Negative electrode collector 14 Positive electrode terminal 15 Negative electrode terminals 16, 17 Extraction part 18 Lithium electrode 18a Lithium electrode current collector 19 Lithium electrode extraction member 20 Exterior body 21A Upper exterior film 21B Lower exterior film 22 Joint part 22a One side 22b of joint part 23 Other part of joint part 23 Non-joint part 25 Safety valve 26 Seal part 27 Hole Part 30 First fixing member 30a One end part 30b Other end part 31 Second fixing member 31a One end part 31b Other end parts 33a to 33d Broken line-like cut 33e Triangular cut 33f Linear cut 33g Diamond cut S Separator

Claims (9)

An electricity storage device element in which a positive electrode and a negative electrode are stacked via a separator and an electrolytic solution are accommodated in an exterior body, and the interior of the exterior body is electrically connected to the positive electrode and the negative electrode constituting the electrical storage device, respectively. Is an electricity storage device comprising a positive electrode terminal and a negative electrode terminal provided so as to protrude from the exterior body to the outside,
The electrical storage device element is provided with an insulating first fixing member that fixes the positive electrode, the negative electrode, and the separator that constitute the electrical storage device element and that is unfixed at a temperature of 90 ° C. or higher and 160 ° C. or lower. A power storage device characterized.   The power storage device according to claim 1, wherein the first fixing member is made of a meltable material having a melting point of 90 ° C. or higher and 160 ° C. or lower.   3. The power storage device according to claim 1, wherein the first fixing member has a tape shape and is arranged to extend in a stacking direction of a positive electrode, a negative electrode, and a separator in the power storage device element. .   The electric storage device according to claim 2 or 3, wherein the meltable material is made of at least one thermoplastic resin selected from polyethylene and polypropylene.   The power storage device according to claim 1, wherein at least one of an intermittent cut portion and a cutout portion is provided in the first fixing member. The positive electrode terminal and the negative electrode terminal protrude in a direction perpendicular to the stacking direction of the positive electrode, the negative electrode, and the separator in the electricity storage device element;
The power storage device element is provided with an insulating second fixing member that can fix the positive electrode, the negative electrode, and the separator constituting the power storage device element even after the solid from the first fixing member is removed. And
The said 2nd fixing member is arrange | positioned in the side surface of the direction which cross | intersects the protrusion direction of the said positive electrode terminal or the said negative electrode terminal in the said electrical storage device element. An electricity storage device according to claim 1. The positive electrode terminal and the negative electrode terminal protrude in a direction perpendicular to the stacking direction of the positive electrode, the negative electrode, and the separator in the electricity storage device element;
The said 1st fixing member is arrange | positioned by the side surface of the direction in alignment with the protrusion direction of the said positive electrode terminal or the said negative electrode terminal in the said electrical storage device element. The electricity storage device described in 1.   Charge and discharge are performed with a current of 50 A or more, and the electricity storage device according to any one of claims 1 to 7. It is a lithium ion capacitor, The electrical storage device in any one of Claims 1-8 characterized by the above-mentioned.

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