JP7171351B2 - LAMINATED SECONDARY BATTERY AND MANUFACTURING METHOD THEREOF - Google Patents

Description

TECHNICAL FIELD The present invention relates to a laminated secondary battery and a method for manufacturing a laminated secondary battery.

2. Description of the Related Art In recent years, a laminate type secondary battery manufactured by sealing a battery element (electrode assembly) in a laminate outer package has been widely used. Laminate sheaths are typically made using a sheath material that has a thin metal layer, such as aluminum, and a sealant layer laminated on the metal layer. By folding one sheet of the exterior material or by laminating two sheets of the exterior material, the exterior materials arranged facing each other are heated and welded to obtain a laminated exterior body that seals the battery element.

Oppositely positioned facings to form a laminate facing are positioned such that the sealant layers face each other. The sealant layer usually contains a thermoplastic resin. By bringing the heat bar into contact with the exterior material to heat the exterior material, the two facing sealant layers are welded to join (seal) the two laminated exterior materials.

Japanese Patent Publication No. 2014-517458 JP 2017-130374 A

However, when the heat bar is used to weld the exterior material, the melted sealant material may leak from the peripheral edge portion of the laminated exterior body and adhere to the heat bar. The sealant material adhering to the heat bar adheres to the laminated outer packaging to be treated later, and stains the laminated outer packaging. In order to avoid such problems, it is necessary to remove the sealant material adhering to the heat bar each time. Such cleaning work of the heat bar significantly impairs the productivity of the laminated secondary battery.

The present invention has been made in view of the above points, and aims at improving the productivity of laminated secondary batteries.

A method for manufacturing a laminated secondary battery according to the present invention comprises:
A method of manufacturing a laminate type secondary battery having a laminated outer package formed using an outer packaging material including a metal layer and a sealant layer laminated on the metal layer, and an electrode body arranged in the laminated outer package. and
A step of contacting a heat bar to a portion of the laminate housing housing the electrode body where the exterior materials are arranged to face each other to weld the facing exterior materials,
The heat bar contacts a contact area located inside the peripheral edge of the laminated outer body.

In the method for manufacturing a laminate type secondary battery according to the present invention, the contact area may be separated from the peripheral edge of the laminate outer package by 0.5 mm or more.

A method for manufacturing a laminated secondary battery according to the present invention comprises:
A step of contacting a heat bar with the second contact area of the laminated outer body to weld facing facing outer materials,
One longitudinal edge of the second contact area may be located within the contact area, or one longitudinal edge of the contact area may be located within the second contact area. .

In the method for manufacturing a laminated secondary battery according to the present invention,
An overlapping area between the contact area and the second contact area has a length in the longitudinal direction of the contact area that is equal to or greater than two-fifths of the width of the second contact area along the longitudinal direction of the contact area. death,
The overlap region may have a length in the longitudinal direction of the second contact region that is equal to or greater than two fifths of the width of the contact region along the longitudinal direction of the second contact region.

A method for manufacturing a laminated secondary battery according to the present invention comprises:
A step of contacting a heat bar with the third contact area of the laminated outer body to weld facing facing outer materials,
One longitudinal edge of the third contact area may be located within the contact area, or the other longitudinal edge of the contact area may be located within the third contact area. .

In the method for manufacturing a laminated secondary battery according to the present invention,
The laminated exterior body has a rectangular shape in plan view,
The contact area, the second contact area, and the third contact area may extend linearly along each of three mutually different edges of the rectangular shape.

The laminated secondary battery according to the present invention is
A laminated exterior body formed using an exterior material including a metal layer and a sealant layer laminated on the metal layer;
an electrode body having a plurality of electrodes and housed in the laminate outer body,
The laminated exterior body has a linear welded portion to which exterior materials arranged to face each other are welded,
The thickness of the welded portion of the laminated outer body is greater at both end portions in the longitudinal direction of the welded portion than at a portion located between the end portions.

In the laminate-type secondary battery according to the present invention, the welded portions may be connected to edges of the laminate exterior body at the both end portions.

In the laminated secondary battery according to the present invention, the total thickness of the sealant layer at the both end portions of the welded portion of the laminated outer body is positioned between the both end portions of the welded portion of the laminated outer body. It may be more than twice the total thickness of the sealant layer at the portion where the sealant layer is formed.

In the laminated secondary battery according to the present invention, the thickness of the welded portion of the laminated outer body may be maximized at the both end portions.

In the laminated secondary battery according to the present invention,
The laminated exterior body further has a linear second welded portion to which exterior materials arranged linearly extending across the welded portion and facing each other are welded,
The thickness of the laminated outer body at the welded portion is thicker at the end portion located between the overlapping portion and the edge portion of the laminated outer body than at the overlapping portion intersecting the second welded portion. may

In the laminated secondary battery according to the present invention, the thickness of the end portion of the laminated outer package may be at least twice the thickness of the overlapping portion of the laminated outer package.

ADVANTAGE OF THE INVENTION According to this invention, productivity of a lamination type secondary battery can be improved by suppressing adhesion of the sealant material to a heat bar.

FIG. 1 is a diagram for explaining an embodiment of the present invention, and is a perspective view showing a laminated secondary battery. FIG. 2 is a perspective view showing the inside of the laminate-type secondary battery of FIG. 1 with the laminate exterior body, the insulator, etc. removed. FIG. 3 is a vertical cross-sectional perspective view for explaining a laminated structure of electrode plates and insulators of the laminated secondary battery of FIG. 4 is a top view showing electrode plates and insulators of the laminated secondary battery of FIG. 1. FIG. 5 is a vertical cross-sectional view showing a cross section along the width direction of the laminated secondary battery of FIG. 1. FIG. FIG. 6 is a partial vertical cross-sectional view showing a cross section of the laminated secondary battery of FIG. 1 along the extraction direction. FIG. 7 is a plan view showing the laminated secondary battery of FIG. 1, and is a diagram for explaining a contact region and a welded portion by a heat bar. FIG. 8 is a diagram for explaining the method of manufacturing the laminated secondary battery of FIG. 1, and is a cross-sectional view showing a step of forming a welded portion. FIG. 9 is an enlarged view of FIG. 7 for explaining the positional relationship between the first contact area and the second contact area. FIG. 10 is a diagram corresponding to FIG. 9 and for explaining a modified example of the positional relationship between the first contact area and the second contact area. FIG. 11 is a diagram corresponding to FIG. 9 and for explaining another modification of the positional relationship between the first contact area and the second contact area. FIG. 12 is a diagram corresponding to FIG. 9 and for explaining still another modification of the positional relationship between the first contact area and the second contact area. FIG. 13 is a diagram corresponding to FIG. 9 and for explaining still another modification of the positional relationship between the first contact area and the second contact area. FIG. 14 is a cross-sectional view taken along line XIV-XIV in FIG. 9 for explaining the thickness of the laminated outer package. FIG. 15 is a plan view schematically showing a laminated secondary battery according to an example. FIG. 16 is a diagram corresponding to FIG. 8, and is a diagram for explaining a conventional method for manufacturing a laminated secondary battery.

An embodiment of the present invention will be described below with reference to the drawings. In addition, in the drawings attached to this specification, for the convenience of easy understanding, the scale, the ratio of vertical and horizontal dimensions, etc. are appropriately changed and exaggerated from those of the real thing.

1 to 14 are diagrams for explaining an embodiment of the present invention.

In one embodiment described below, the laminate-type secondary battery 1 includes a laminate outer package 40, an electrode body 5 housed in the laminate outer package 40, and the laminate outer package 40 connected to the electrode body 5. and a tab 3 extending from the inside to the outside. Of these, the laminated exterior body 40 is formed by welding the peripheral edges of the exterior materials 41 arranged so as to face each other. That is, welded portions MJ1, MJ2, and MJ3 formed by welding (adhering) two opposing portions 41A and 41B of the exterior material 41 are provided on the peripheral edge of the laminate exterior body 40 . The tab 3 passes between the two portions 41A and 41B of the exterior material 41 and extends from the inside of the laminate exterior body 40 to the outside. The electrode body 5 has first electrode plates 10 and second electrode plates 20 that are alternately laminated, and an insulator 30 positioned between the first electrode plates 10 and the second electrode plates 20 .

An example in which the laminated secondary battery 1 constitutes a laminated lithium ion secondary battery will be described below. In this example, the first electrode plate 10 constitutes the positive electrode plate 10X, and the second electrode plate 20 constitutes the negative electrode plate 20Y. However, as can be understood from the description of the effects described below, one embodiment described here is not limited to lithium ion secondary batteries, and can also be applied to secondary batteries other than lithium ion. Furthermore, it is applicable not only to laminated secondary batteries but also to wound secondary batteries. That is, the present embodiment can be widely applied to the laminate type secondary battery 1 in which the electrode body 5 is accommodated in the laminate outer package 40 .

First, the configuration of the laminate outer package 40 will be described. The laminate outer package 40 is a packaging material for sealing the electrode body 5 . As shown in FIGS. 1, 5, and 6, the laminated outer body 40 has outer materials 41 that are arranged to face each other. The laminated exterior body 40 may include two separate exterior materials 41, or as in the illustrated example, one sheet of exterior material 41 may be folded back to form a first portion 41A and a first portion 41A of the exterior material 41 facing each other. You may make it contain the 2nd part 41B. The exterior material 41 has a metal layer 44 and a sealant layer 45 laminated on the metal layer 44 (see FIGS. 5 and 6). The metal layer 44 preferably has high gas barrier properties and moldability.

The material forming the metal layer 44 is not particularly limited as long as it prevents moisture from entering from the outside and improves the strength of the entire laminated secondary battery. Metals, metal oxides, metal nitrides, and alloys thereof can be used, with aluminum, aluminum alloys, stainless steel and the like being preferred, and aluminum being particularly preferred. Instead of the metal foil, a metal layer may be provided by vapor deposition, sputtering, or the like, as long as the strength of the entire battery can be secured.

The sealant layer 45 has insulating properties, and prevents short circuits between the electrode plates 10 and 20 and the metal layer 44 accommodated in the laminated exterior body 40 . Moreover, the sealant layer 45 has thermoplasticity (adhesiveness) in addition to insulation. The first portion 41A and the second portion 41B of the exterior material 41 are laminated such that the sealant layers 45 face each other. The first portion 41A and the second portion 41B of the exterior material 41 are welded to each other except for the folded portion RP where the exterior material 41 is folded in the peripheral edge portion ce of the laminated exterior body 40 . Furthermore, a housing space RS for the electrode body 5 is formed between the first portion 41A and the second portion 41B of the exterior material 41 . The laminated exterior body 40 hermetically seals the electrode assembly 5 and the electrolytic solution in its accommodation space RS. Since the sealant layer 45 is also in contact with the electrolytic solution, it preferably has chemical resistance. Polyolefin-based resins such as polypropylene, modified polypropylene, low-density polypropylene, ionomer, and ethylene-vinyl acetate can be used as the material for such a sealant layer 45 .

In the illustrated example, the first portion 41A of the exterior material 41 is a plate-like member. On the other hand, the second portion 41B of the exterior material 41 is formed in a cup shape. The second portion 41B has a cup-shaped swelling portion 42a and a collar portion 42b connected to the swelling portion 42a. The flange portion 42b surrounds the bulging portion 42a in a circumferential shape and is connected to the peripheral edge of the bulging portion 42a. The flange portion 42b is welded to the second portion 41B so as to seal the accommodation space RS between the first portion 41A and the second portion 41B. The bulging portion 42 a may be manufactured by drawing, for example, or may be a portion formed by deforming the flexible exterior material 41 according to the electrode body 5 .

However, it is not limited to the above example, and the laminated exterior body 40 may have two exterior materials. The sealed housing space RS can be formed by circumferentially welding the two exterior materials at the position that will be the peripheral edge portion ce of the laminated exterior body 40 .

Tab 3 functions as a terminal in laminate type secondary battery 1 . One tab 3 is electrically connected to the positive electrode plate 10X (first electrode plate 10) of the electrode assembly 5, and the other tab 3 is electrically connected to the negative electrode plate 20Y (second electrode plate 20) of the electrode assembly 5. is doing. Tab 3 may be formed using aluminum, nickel, nickel-plated copper, or the like. The pair of tabs extends from the inside of the laminated outer body 40 to the outside of the laminated outer body 40 . In the illustrated example, the tab 3 is pulled out from the electrode assembly 5 along the extraction direction dx to the outside of the laminated exterior body 40 .

The area between the laminated outer body 40 and the tab 3 is sealed in the area where the tab 3 extends. Specifically, as shown in FIGS. 1 and 6, a sealing material 4 is provided between the tab 3 and the laminated outer body 40. As shown in FIG. The sealing material 4 seals between the tab 3 and the laminated outer body 40 to seal the housing space RS of the laminated outer body 40 . Moreover, the sealing material 4 has adhesiveness, and joins the tab 3 and the laminated outer body 40 . As shown well in FIG. 6, seal members 4 are provided on both sides of the tab 3 in the stacking direction dz of the electrode plates 10 and 20, respectively.

As well shown in FIG. 7, in the illustrated laminate-type secondary battery 1, the laminate outer casing 40 has a rectangular shape in plan view. The illustrated laminated outer body 40 has a longitudinal direction in the pull-out direction dx in which the tab 3 extends, and a width direction dy perpendicular to the pull-out direction dx. Therefore, the laminated exterior body 40 has a pair of long edges (first edge e1 and fourth edge e4) parallel to the pull-out direction dx and a pair of short edges parallel to the width direction dy as the peripheral edge ce. (second edge e2 and third edge e3). Among them, the fourth edge e4 is a folded portion RP formed by folding the exterior material 41. As shown in FIG. The laminate outer body 40 includes a first welded portion MJ1 linearly extending along the first edge e1, a second welded portion MJ2 linearly extending along the second edge e2, and a third edge and a third welded portion MJ3 extending linearly along e3. At the welding portions MJ1, MJ2, and MJ3, exterior materials 41 arranged facing each other are welded. The second welded portion MJ2 is connected to the first welded portion MJ1 and the folded portion RP at both ends thereof. Similarly, the third welded portion MJ3 is connected at both ends thereof to the first welded portion MJ1 and the folded portion RP. The housing space RS is partitioned and sealed by the welded portions MJ1, MJ2, MJ3 and the folded portion RP.

Next, the electrode assembly 5 will be described mainly with reference to the illustrated specific examples. The electrode body 5 has a positive electrode plate 10X (first electrode plate 10), a negative electrode plate 20Y (second electrode plate 20), and an insulator 30 positioned between the positive electrode plate 10X and the negative electrode plate 20Y. . Of these, first, the positive electrode plate 10X and the negative electrode plate 20Y will be described.

As shown in FIGS. 2, 3, 5 and 6, the electrode body 5 has a plurality of positive electrode plates 10X (first electrode plates 10) and negative electrode plates 20Y (second electrode plates 20). The positive electrode plate 10X (first electrode plate 10) and the negative electrode plate 20Y (second electrode plate 20) are arranged in one laminated outer body 40, for example, 10 or more each, or 15 or more each, or 20 or more each. include. The positive electrode plates 10X and the negative electrode plates 20Y are alternately arranged along the stacking direction dz. The electrode body 5 and the laminate type secondary battery 1 have a flat shape as a whole, are thin in the stacking direction dz, and extend in the lead-out direction dx perpendicular to the stacking direction dz and in the width direction dy.

In addition, in order to clarify the directional relationship among the drawings, some drawings show the lead-out direction dx, the width direction dy, and the stacking direction dz as common directions among the drawings.

In the illustrated non-limiting example, the positive plate 10X and the negative plate 20Y have rectangular contours. The positive electrode plate 10X and the negative electrode plate 20Y have a longitudinal direction in the lead-out direction dx perpendicular to the stacking direction dz, and a width direction dy perpendicular to both the stacking direction dz and the lead-out direction dx. As shown in FIGS. 2 and 4, the positive electrode plate 10X and the negative electrode plate 20Y are staggered in the pull-out direction dx. More specifically, the plurality of positive plates 10X are arranged closer to one side (the lower left side in FIG. 2 and the left side in FIG. 4) in the pull-out direction dx, and the plurality of negative plates 20Y are arranged on the other side in the pull-out direction dx. (upper right side in FIG. 2 and right side in FIG. 4). The positive electrode plate 10X and the negative electrode plate 20Y overlap each other in the stacking direction dz at the center in the extraction direction dx. 2, illustration of the insulator 30 is omitted.

As illustrated, the positive electrode plate 10X (first electrode plate 10) has a sheet-like outer shape. The positive electrode plate 10X (first electrode plate 10) includes a positive electrode current collector 11X (first electrode current collector 11) and a positive electrode active material layer 12X (first electrode active material layer 12X) provided on the positive electrode current collector 11X. 12) and. In the lithium ion secondary battery, the positive electrode plate 10X releases lithium ions during discharging and absorbs lithium ions during charging.

The positive electrode current collector 11X has, as main surfaces, a first surface 11a and a second surface 11b facing each other. The cathode active material layer 12X is formed on at least one of the first surface 11a and the second surface 11b of the cathode current collector 11X. Specifically, when the first surface 11a or the second surface 11b of the positive electrode current collector 11X is positioned at the outermost side in the stacking direction dz of the electrode plates 10 and 20 included in the electrode body 5, the positive electrode collector The positive electrode active material layer 12X is not provided on the outermost surface of the electric body 11X. Except for the presence or absence of the positive electrode active material layer 12X depending on the position of the positive electrode current collector 11X, the plurality of positive electrode plates 10X included in the laminate type secondary battery 1 have positive electrode active material layers 12X on both sides of the positive electrode current collector 11X. and can be configured identically to each other.

The positive electrode current collector 11X and the positive electrode active material layer 12X can be produced by various manufacturing methods using various materials that can be applied to the laminated secondary battery 1 (lithium ion secondary battery). As an example, the positive electrode current collector 11X may be made of aluminum foil. The positive electrode active material layer 12X contains, for example, a positive electrode active material, a conductive aid, and a binding agent that serves as a binder. The positive electrode active material layer 12X is produced by applying a positive electrode slurry obtained by dispersing a positive electrode active material, a conductive aid, and a binder in a solvent onto the material forming the positive electrode current collector 11X and solidifying the slurry. can be As the positive electrode active material, for example, a lithium metal oxide compound represented by the general formula LiM _x O _y (where M is a metal, and x and y are the composition ratio of metal M and oxygen O) is used. Specific examples of the lithium metal oxide compound include lithium cobaltate, lithium nickelate, and lithium manganate. Acetylene black or the like may be used as the conductive aid. Polyvinylidene fluoride or the like may be used as the binder.

As shown in FIG. 4, the positive electrode current collector 11X (first electrode current collector 11) has a first end region a1 and a first electrode region b1. The positive electrode active material layer 12X (first electrode active material layer 12) is arranged only in the first electrode region b1 of the positive electrode current collector 11X. The first end region a1 and the first electrode region b1 are arranged in the extraction direction dx. The first end region a1 is located outside (to the left in FIG. 4) in the lead-out direction dx of the first electrode region b1. As shown in FIG. 6, the plurality of positive electrode current collectors 11X are joined and electrically connected in the first end region a1 by resistance welding, ultrasonic welding, sticking with tape, fusion bonding, or the like. . In the illustrated example, one tab 3 is electrically connected to the positive current collector 11X at the first end region a1. The tab 3 extends from the electrode body 5 in the extraction direction dx. On the other hand, as shown in FIG. 4, the first electrode region b1 is located within a region of the negative electrode plate 20Y facing the negative electrode active material layer 22Y, which will be described later. As shown in FIG. 5, the width of the positive electrode plate 10X along the width direction dy is narrower than the width of the negative electrode plate 20Y along the width direction dy. Such arrangement of the first electrode region b1 can prevent deposition of lithium from the positive electrode active material layer 12X.

Next, the negative electrode plate 20Y (second electrode plate 20) will be described. Similarly to the positive plate 10X, the negative plate 20Y also has a sheet-like outer shape. The negative electrode plate 20Y (second electrode plate 20) includes a negative electrode current collector 21Y (second electrode current collector 21) and a negative electrode active material layer 22Y (second electrode active material layer) provided on the negative electrode current collector 21Y. 22) and In the lithium ion secondary battery, the negative electrode plate 20Y absorbs lithium ions during discharging and releases lithium ions during charging.

The negative electrode current collector 21Y has a first surface 21a and a second surface 21b facing each other as main surfaces. The negative electrode active material layer 22Y is formed on at least one of the first surface 21a and the second surface 21b of the negative electrode current collector 21Y. Specifically, when the first surface 21a or the second surface 21b of the negative electrode current collector 21Y is positioned at the outermost side in the stacking direction dz of the electrode plates 10 and 20 included in the electrode assembly 5, The negative electrode active material layer 22Y is not provided on the outermost surface of the electric body 21Y. Except for the presence or absence of the negative electrode active material layer 22Y depending on the position of the negative electrode current collector 21Y, the plurality of negative electrode plates 20Y included in the laminate type secondary battery 1 have the negative electrode active material layers 22Y on both sides of the negative electrode current collector 21Y. and can be configured identically to each other.

The negative electrode current collector 21Y and the negative electrode active material layer 22Y can be produced by various manufacturing methods using various materials that can be applied to the laminate type secondary battery 1 (lithium ion secondary battery). As an example, the negative electrode current collector 21Y is made of copper foil, for example. The negative electrode active material layer 22Y contains, for example, a negative electrode active material made of a carbon material and a binder that functions as a binder. The negative electrode active material layer 22Y is formed by dispersing a negative electrode slurry in which a negative electrode active material such as carbon powder or graphite powder and a binder such as polyvinylidene fluoride are dispersed in a solvent to form the negative electrode collector 21Y. It can be made by coating on a material and solidifying it.

As shown in FIG. 4, the negative electrode current collector 21Y (second electrode current collector 21) has a second end region a2 and a second electrode region b2. The negative electrode active material layer 22Y (second electrode active material layer 22) is arranged in the second electrode region b2 of the negative electrode current collector 21Y. The second end region a2 and the second electrode region b2 are arranged in the extraction direction dx. The second end region a2 is located outside the second electrode region b2 in the drawing direction dx (to the right in FIG. 4). The plurality of negative electrode current collectors 21Y are joined and electrically connected in the second end region a2 by resistance welding, ultrasonic welding, sticking with a tape, fusion bonding, or the like. One tab 3 can be electrically connected to the negative electrode current collector 21Y at the second end region a2. The tab 3 extends from the electrode body 5 in the extraction direction dx.

As already explained, the first electrode region b1 of the positive electrode plate 10X is positioned inside the region facing the second electrode region b2 of the negative electrode plate 20Y (see FIG. 4). That is, the second electrode region b2 extends over a region that includes the region facing the positive electrode active material layer 12X of the positive electrode plate 10X. As shown in FIG. 5, the width of the negative electrode plate 20Y along the width direction dy is wider than the width of the positive electrode plate 10X along the width direction dy.

Next, the insulator 30 will be explained. The insulator 30 is positioned between the positive electrode plate 10X (first electrode plate 10) and the negative electrode plate 20Y (second electrode plate 20). The insulator 30 prevents a short circuit due to contact between the positive electrode plate 10X (first electrode plate 10) and the negative electrode plate 20Y (second electrode plate 20). The insulator 30 preferably has a high ion permeability (air permeability), a predetermined mechanical strength, and durability against the electrolytic solution, the positive electrode active material, the negative electrode active material, and the like. As such an insulator 30, for example, a porous body or a non-woven fabric made of an insulating material can be used. An electrolytic solution is enclosed in the laminated outer package 40 together with the electrode assembly 5 . By impregnating the insulator 30 made of a porous material or a non-woven fabric with the electrolytic solution, the electrode active material layers 12 and 22 of the electrode plates 10 and 20 are kept in contact with the electrolytic solution.

In the illustrated example, a single insulator 30 is positioned between any two adjacent electrode plates 10, 20 in the stacking direction dz. The insulator 30 is a bendable sheet-like member. The insulator 30 has a first surface 30a and a second surface 30b as a pair of main surfaces facing each other. As shown in FIGS. 3 and 5, the insulator 30 is alternately folded in the opposite direction in the width direction dy, thereby sequentially extending between the positive electrode plate 10X and the negative electrode plate 20Y adjacent to each other in the stacking direction dz. The insulator 30 has a first folded portion 31 folded on one side in the width direction dy and a second folded portion 32 folded on the other side opposite to the one side in the width direction dy. That is, the insulator 30 has a zigzag shape. However, in the present embodiment, the insulator 30 does not need to have a zigzag shape. 20) to insulate the positive electrode plate 10X (first electrode plate 10) and the negative electrode plate 20Y (second electrode plate 20).

As shown in FIG. 4, in plan view, the insulator 30 spreads so as to cover the entire area of the positive electrode active material layer 12X of the positive electrode plate 10X. Therefore, as shown in FIG. 5, the width of the insulator 30 in the width direction dy is wider than the width of the positive electrode plate 10X in the width direction dy. In addition, the length of the insulator 30 in the extraction direction dx is longer than the length of the positive electrode active material layer 12X in the extraction direction dx.

Similarly, as shown in FIG. 4, in plan view, the insulator 30 extends so as to cover the entire region of the negative electrode active material layer 22Y of the negative electrode plate 20Y. That is, the width of the insulator 30 in the width direction dy is wider than the width of the negative electrode plate 20Y in the width direction dy. In addition, the length of the insulator 30 in the extraction direction dx is longer than the length of the negative electrode active material layer 22Y in the extraction direction dx.

A resinous porous film can be used as the insulator 30 as described above. More specifically, a porous film made of a thermoplastic resin having a melting point of about 80 to 140° C. can be used as the insulator 30 . Polyolefin resins such as polypropylene and polyethylene can be used as thermoplastic resins.

Alternatively, the insulator 30 may have a base layer and a functional layer laminated on the base layer. According to such a configuration, the first surface 30a of the insulator 30 facing the positive electrode plate 10X and the second surface 30b of the insulator 30 facing the negative electrode plate 20Y can have different properties. can. For example, a functional layer having a large porosity may face the negative electrode plate 20Y, which has a large area and the electrolytic solution tends to dry up, and the base material layer may face the positive electrode plate 10X. As another example, the functional layer having excellent heat resistance may face the positive electrode plate 10X whose temperature is likely to rise, and the base material layer may face the negative electrode plate 20Y. As the substrate layer, for example, the porous resin film described immediately before can be used. As the functional layer, for example, a layer containing an inorganic material can be employed. The inorganic material can provide the functional layer with excellent heat resistance, for example, heat resistance of 150° or higher. Examples of such inorganic materials include fibrous materials and particulate materials such as cellulose and modified products thereof, polyolefin, polyethylene terephthalate, polybutylene terephthalate, polypropylene, polyester, polyacrylonitrile, aramid, polyamideimide, and polyimide. By using such an inorganic material, it is also possible to give the functional layer a higher porosity than the substrate layer.

Next, a method for manufacturing the laminate type secondary battery 1 having the configuration as described above will be described.

First, the electrode body 5 is produced by laminating the positive electrode plate 10X, the negative electrode plate 20Y, and the insulator 30 for insulating the positive electrode plate 10X and the negative electrode plate 20Y. The positive electrode plate 10X, the negative electrode plate 20Y, and the insulator 30 can be manufactured using the materials and manufacturing methods described above. Next, the fabricated positive electrode plate 10X, negative electrode plate 20Y and insulator 30 are stacked such that the insulator 30 is positioned between the positive electrode plate 10X and the negative electrode plate 20Y. Thereby, the electrode body 5 is obtained. After that, the positive electrode current collectors 11X of the plurality of positive electrode plates 10X are electrically connected to each other, and the tabs 3 are also electrically connected. Similarly, the negative electrode current collectors 21Y of the plurality of negative electrode plates 20Y are electrically connected to each other, and the tabs 3 are also electrically connected.

Next, an exterior material 41 that constitutes the laminated exterior body 40 is prepared. The first portion 41A and the second portion 41B of the exterior material 41 face each other by folding the exterior material 41 at the folded portion RP. The sealant layer 45 is positioned inside the folded exterior material 41 . Next, the electrode body 5 is arranged between the first portion 41A and the second portion 41B. At this time, each tab 3 extends from between the first portion 41A and the second portion 41B of the first exterior member 41, as shown in FIG.

It should be noted that the bulging portion 42a may be formed in advance in the region of the exterior material 41 that will become the second portion 41B, for example, by drawing. In this example, the electrode body 5 is accommodated in the bulging portion 42a.

Next, in a state in which the electrode body 5 is arranged between the first portion 41A and the second portion 41B of the exterior material 41, the first portion 41A and the second portion 41A of the exterior material 41 are positioned to surround the bulging portion 42a from three sides. The two parts 41B are welded. In the illustrated example, the first portion 41A and the second portion 41B facing each other are welded to form three welded portions MJ1 to MJ3 in order.

The first welded portion MJ1 is formed along the first edge e1 of the laminated outer body 40 . The first welded portion MJ1 extends linearly along the pull-out direction dx. In the illustrated example, the first welded portion MJ1 is connected to a pair of edge portions of the laminated exterior body 40 facing in the pull-out direction dx, that is, the second edge portion e2 and the third edge portion e3.

The second welded portion MJ2 is formed along the second edge e2 of the laminated outer body 40 . The second welded portion MJ2 extends linearly along the width direction dy. In the illustrated example, the second welded portion MJ2 is connected to a pair of edge portions of the laminated exterior body 40 facing each other in the width direction dy, that is, the first edge portion e1 and the fourth edge portion e4. Similarly, the third welded portion MJ3 is formed along the third edge e3 of the laminated outer body 40 . The third welded portion MJ3 extends linearly along the width direction dy. In the illustrated example, the third welded portion MJ3 is connected to a pair of edge portions of the laminated exterior body 40 facing each other in the width direction dy, that is, the first edge portion e1 and the fourth edge portion e4.

The order of forming the three welded portions MJ1 to MJ3 is not particularly limited. Also, since the second welded portion MJ2 and the third welded portion MJ3 are not connected to each other, they can be formed in parallel. Moreover, when forming the final welded portion, the electrolytic solution is accommodated in the accommodation space RS of the laminated outer body 40 closed from three sides. As an example, the second welded part MJ2 and the third welded part MJ3 are produced in order or in parallel, then the electrolytic solution is filled in the laminated exterior body 40, and then the first welded part MJ1 is produced. You may do so.

The welded portions MJ1 to MJ3 are formed using a sealing device 50 having a heat bar 51 as a rod-shaped heating member, as shown in FIG. By pressing a pair of heated heat bars 51 against the exterior material 41 from both sides, the sealant layers 45 of the first portion 41A and the second portion 41B are melted and then solidified to form the first portion 41A and the second portion. 41B is welded. At the second welded portion MJ2 and the third welded portion MJ3, the tab 3 is provided with the exterior material 41, and the sealing material 4 is welded to the exterior material 41 to provide a gap between the tab 3 and the exterior material 41. Seal. When forming each welded portion MJ1 to MJ3, another heat bar 51 having a length corresponding to each welded portion can be used.

As shown in FIG. 16 , conventionally, when a heat bar 151 is used to weld the exterior material 141 , the melted sealant material 146 may leak out from the peripheral edge portion ce of the laminate exterior body 140 and adhere to the heat bar 151 . rice field. The sealant material 146 adhering to the heat bar 151 adheres to the laminated outer body 140 to be processed later, and stains the laminated outer body 140 . In order to avoid such a problem, it is necessary to remove the sealant material 146 adhering to the heat bar 151 each time. Such cleaning work of the heat bar 151 significantly impairs the productivity of the laminated secondary battery 101 .

Conventionally, it was considered necessary to apply heat and pressure by pressing the heat bar 151 over the entire width of the portion to be welded in order to reliably weld the facing members 141 . Therefore, when the welded portion is formed over the entire width of the exterior material 41, as shown in FIG. By using the heat bar 151 longer than the full width of the exterior material 141 , the sealant layer 145 laminated on the metal layer 144 could be melted over the entire width of the exterior material 41 . On the other hand, the melted sealant material 146 was squeezed out from the peripheral edge portion ce of the laminated exterior body 140 and adhered to the heat bar 151 .

Therefore, in the present embodiment, as shown in FIGS. 7 and 8, the heat bar 51 is prevented from coming into contact with the peripheral edge portion ce of the laminated exterior body 40 from which the sealant material may be squeezed out. According to this embodiment, productivity can be improved. Furthermore, in the laminated secondary battery 1 manufactured by the method according to the present embodiment, the exterior material 41 can be welded more firmly to improve the sealing performance of the housing space RS. It can be said that such an effect is different and remarkable beyond the scope expected from the conventional technical level.

In the illustrated example, when forming the second welded portion MJ2, the heat bar 51 contacts the second contact area CT2 to heat and pressurize it. The second contact area CT2 extends linearly along the second edge e2 of the laminate outer body 40 . The second contact area CT2 includes a pair of edges EE2, EE2 facing in the width direction dy, and an outer edge OE2 and an inner edge IE2 facing in the drawing direction dx. One edge EE2 is positioned near the first edge e1 and extends parallel to the drawing direction dx along the first edge e1. The other edge EE2 is positioned near the fourth edge e4 and extends parallel to the drawing direction dx along the fourth edge e4. The inner edge IE2 is closer to the accommodation space RS than the outer edge OE2. The outer edge OE2 is closer to the second edge e2 than the inner edge IE2. The outer edge OE2 and the inner edge IE2 extend parallel to the width direction dy along the second edge e2.

When forming the third welded portion MJ3, the heat bar 51 contacts the third contact region CT3 to apply heat and pressure. The third contact area CT3 extends linearly along the third edge e3 of the laminated outer body 40 . The third contact region CT3 includes a pair of edges EE3, EE3 facing in the width direction dy, and an outer edge OE3 and an inner edge IE3 facing in the extraction direction dx. One edge EE3 is located near the first edge e1 and extends parallel to the drawing direction dx along the first edge e1. The other edge EE3 is located near the fourth edge e4 and extends parallel to the drawing direction dx along the fourth edge e4. The inner edge IE3 is closer to the accommodation space RS than the outer edge OE3. The outer edge OE3 is closer to the third edge e3 than the inner edge IE3. The outer edge OE3 and the inner edge IE3 extend parallel to the width direction dy along the third edge e3.

When forming the first welded portion MJ1, the heat bar 51 contacts the first contact region CT1 to apply heat and pressure. The first contact area CT1 extends linearly along the first edge e1 of the laminated outer body 40. As shown in FIG. The first contact region CT1 includes a pair of edges EE1, EE1 facing in the drawing direction dx, and an outer edge OE3 and an inner edge IE3 facing in the width direction dy. One edge EE1 is positioned near the second edge e2 and extends parallel to the width direction dy along the second edge e2. The other edge EE1 is positioned near the third edge e3 and extends parallel to the width direction dy along the third edge e3. The inner edge IE1 is closer to the accommodation space RS than the outer edge OE1. The outer edge OE1 is closer to the first edge e1 than the inner edge IE1. The outer edge OE13 and the inner edge IE1 extend parallel to the extraction direction dx along the first edge e1.

That is, the first contact area CT1, the second contact area CT2, and the third contact area CT3 are all separated from the peripheral edge portion ce of the laminated exterior body 40 and positioned inside the peripheral edge portion ce of the laminated exterior body 40. is doing.

In this way, the area where the heat bar 51 contacts the exterior material 41 is enclosed by the peripheral edge portion ce of the laminated exterior body 40, so that the melted sealant material leaks from the peripheral edge portion ce of the laminated exterior body 40. can be effectively prevented. Therefore, adhesion of the melted sealant material to the heat bar 51 can be effectively avoided, and the productivity of the laminated secondary battery 1 can be effectively improved.

In the illustrated example, the fourth edge e4 of the laminated exterior body 40 is a folded portion RP formed by folding the exterior material 41. As shown in FIG. Therefore, the melted sealant material does not leak from the fourth edge e4. Therefore, the second contact area CT2 and the third contact area CT3 may intersect the fourth edge e4, or the other edges EE2 and EE3 may be located on the fourth edge e4. good.

From the viewpoint of avoiding leakage of the sealant material from the peripheral edge portion ce of the laminated exterior body 40, the contact areas CT1, CT2, and CT3 are preferably separated from the peripheral edge portion ce of the laminated exterior body 40 by 0.5 mm or more. By setting this distance to 0.5 mm or more, the sealant melted from the peripheral edge portion ce of the laminate exterior body 40 under general welding conditions for the laminate exterior body 40 during manufacturing of the laminate type secondary battery 1. Material leakage can be effectively avoided. For example, referring to the first contact region CT1, the separation distance L1x (see FIG. 9) between one end edge EE1 of the first contact region CT1 and the second edge e2 along the extraction direction dx is 0. 0.5 mm or more is preferable. It is preferable that the separation distance along the extraction direction dx between the other edge EE1 of the first contact region CT1 and the third edge e3 is 0.5 mm or more. A separation distance L1y (see FIG. 9) along the width direction dy between the outer edge OE1 of the first contact region CT1 and the first edge e1 is preferably 0.5 mm or more.

As shown in FIG. 7, the first contact area CT1 is preferably connected (overlapping) with the second contact area CT2. In this case, the first welded portion MJ1 formed by the heat bar 51 contacting the first contact region CT1 and the second welded portion MJ2 formed by the heat bar 51 contacting the second contact region CT2 are stabilized. The airtightness of the housing space RS can be ensured more reliably. For the same reason, the first contact area CT1 is preferably connected (overlapping) with the third contact area CT3.

In the example shown in FIG. 9, the edge (EE1) of one contact area (first contact area CT1) is positioned on the outer edge (outer edge OE2) of the other contact area (second contact area CT2). The edge (EE2) of the other contact area (second contact area CT2) is positioned on the outer edge (outer edge OE1) of the one contact area (first contact area CT1). According to such an example, the two formed welded portions (the first welded portion MJ1 and the second welded portion MJ2) can be more reliably connected.

However, the positional relationship between the two contact areas is not limited to the example shown in FIG. 9, and the examples shown in FIGS. 10 to 13, for example, can also be adopted. 9 to 13, one contact area (first contact area CT1) is indicated by a dotted line, and the other contact area (second contact area CT2) is indicated by a dashed line.

First, in the example shown in FIG. 10, one contact region (first welded portion MJ1) and the other contact region (second welded portion MJ2) intersect. That is, one contact region (first welded portion MJ1) crosses the other contact region (second welded portion MJ2). The other contact area (second welded portion MJ2) crosses one contact area (first welded portion MJ1). According to this example, the two formed welded portions (the first welded portion MJ1 and the second welded portion MJ2) can be connected more reliably.

Next, in the examples shown in FIGS. 11 and 12, one edge in the longitudinal direction of one contact area is positioned within the other contact area. In the example shown in FIG. 11, one edge EE1 in the longitudinal direction (leading direction dx) of the first contact region CT1 is located within the second contact region CT2. In the example shown in FIG. 12, one edge EE2 in the longitudinal direction (width direction dy) of the second contact region CT2 is positioned within the first contact region CT1. In the example shown in FIG. 13, the contact areas on one side and the contact area on the other overlap only partly in width along the transverse direction perpendicular to each longitudinal direction. According to the examples shown in FIGS. 9 and 11 to 13, the lengths L1 and L2 from each contact area to the peripheral edge portion ce of the laminated exterior body 40 can be reduced. This also makes it possible to improve the energy density of the laminate type secondary battery 1 .

Note that an overlapping area OA between one contact area (first contact area CT1) and the other contact area (second contact area CT2) is a It is preferable to have a length LOx of 2/5 or more of the width of the other contact region (width W2 of the second contact region CT2) along the longitudinal direction, and has a length LOx of 1/2 or more. and more preferably have a length LOx of ⅔. Similarly, the overlap region OA between one contact region (first contact region CT1) and the other contact region (second contact region CT2) is the same as the other contact region in the longitudinal direction (width direction dy) of the other contact region. It is preferable to have a length LOy of 2/5 or more of the width of one contact region (width W1 of the first contact region CT1) along the longitudinal direction of the region, and a length LOx of 1/2 or more. More preferably, it has a length LOx of ⅔. By setting the overlapping area OA to such a size, it is possible to improve sealing performance around the overlapping portion OP where the two welded portions overlap, as described below.

As described above, the pair of heat bars 51 are brought into contact with the exterior material 41 in the second contact area CT2 from both sides to form the second welded portion MJ2, and the pair of heat bars 51 are brought into contact with the exterior material 41 in the third contact area CT3. are brought into contact with each other from both sides, a third welded portion MJ2 is formed. The sealant layer 45 of the exterior material 41 melts not only in the areas overlapping the contact areas CT2 and CT3 with which the heat bar 51 is in contact. The sealant layer 45 also melts around the regions overlapping the contact regions CT2 and CT3. Therefore, as shown in FIG. 7, the region occupied by the second welded portion MJ2 on the laminated outer body 40 includes the region occupied by the second contact region CT2 on the laminated outer body 40. The area occupied by the third welded portion MJ3 on the upper side includes the area occupied by the third contact area CT3 on the laminated outer body 40 .

Similarly, the pair of heat bars 51 are brought into contact with the exterior material 41 from both sides in the first contact regions CT1 to form the first welded portions MJ1. The area occupied by the first welded portion MJ1 on the laminated outer body 40 includes the area occupied by the first contact area CT1 on the laminated outer body 40 . Further, as shown in FIG. 7, the first welded portion MJ1 is connected to or intersects with the second welded portion MJ2 and intersects with the third welded portion MJ3.

In addition, in the overlap region OA between the first contact region CT1 and the second contact region CT2 and its surroundings, the already formed second welded portion MJ2 melts again when the first welded portion MJ1 is formed. Therefore, the first welded portion MJ1 and the second welded portion MJ2 are formed integrally and continuously, and the liquid tightness of the accommodation space RS can be ensured. Similarly, the first welded portion MJ1 and the third welded portion MJ3 are also formed integrally and continuously, and the liquid tightness of the accommodation space RS can be ensured.

As described above, the laminated secondary battery 1 is obtained by forming the welded portions MJ1 to MJ3 in the laminated exterior body 40 and enclosing the electrode assembly 5 and the electrolytic solution in the housing space RS. Surprisingly, the laminated secondary battery 1 obtained in this manner has improved sealing properties of the housing space RS and has high reliability. As a result of confirmation by the inventors of the present invention, the reason why the sealability of the laminate type secondary battery 1 is improved is thought to be due to variations in the thickness of the welded portion resulting from the manufacturing method of the present embodiment. This point will be described below, but the present invention is not bound by the following presumptions.

FIG. 14 is a cross-sectional view showing one welded portion obtained by the above-described method, and corresponds to a cross-section taken along line XIV-XIV in FIG. 9, for example. The first welded portion MJ1 consists of an end portion EP located outside the first contact area CT1, an overlapping portion OP located within the overlapping area OA of the first contact area CT1, and the first contact area CT1. and a central portion MP, which was located outside the overlap region OA. That is, the first welded portion MJ1 includes an end portion EP that has never been pressed by the heat bar 51, an overlapping portion OP that has been pressed twice by the heat bar 51, and a central portion MP that has been pressed once by the heat bar 51. contains.

Then, as shown in FIG. 14, the thickness of the first welded part MJ1 of the laminated outer body 40 at both ends EP in the longitudinal direction of the first welded part MJ1 connected to the peripheral edge part ce of the laminated outer body 40 is: It is thicker than the portions located between the end portions EP (the overlapping portion OP and the central portion MP). In this way, the thickness of the laminate outer body 40 at the portion outside the overlapping portion OP where the two welded portions overlap (on the side opposite to the housing space RS) is increased, so that the sealability of the laminate type secondary battery 1 is increased. could be improved.

In particular, the total thickness of the sealant layer 45 (the total thickness of the two welded sealant layers 45) at the end portion EP of the first welded portion MJ1 of the laminated outer body 40 is If the total thickness of the sealant layer 45 is at least twice the total thickness of the sealant layer 45 in a certain portion (the overlapping portion OP and the central portion MP) other than the portion EP, the airtightness of the laminated secondary battery 1 can be greatly improved. did it.

In addition, in the glass laminate exterior body 40 shown in FIG. 14, the thickness at the first welded portion MJ1 is the maximum at both end portions EP. This point can also contribute to the improvement of the airtightness of the laminate type secondary battery 1 .

The inventor of the present invention has confirmed that, in order to realize the thickness distribution along the longitudinal direction of the welded portion shown in FIG. has a length LOx of 2/5 or more of the width of the other contact area along the longitudinal direction of the other contact area in the longitudinal direction of one contact area, and the other contact In the longitudinal direction of the regions it has been useful to have a length LOy greater than or equal to 2/5 of the width of one contact region along the longitudinal direction of the other contact region. In this case, in experiments conducted by the inventors, the total thickness of the sealant layers 45 included in the first portion 41A and the second portion 41B of the exterior material 41, which are arranged to face each other before welding, is 0.32 mm. Later it increased to 0.58 mm at the end portions EP, decreased to 0.20 mm at the overlap OP and decreased to 0.25 mm at the central portion MP. In the welded portion of the laminate type secondary battery 1 obtained in this experiment, the total thickness of the sealant layer 45 is maximum at the end portion EP, and the total thickness of the sealant layer 45 at the end portion EP is the same as that of the sealant layer other than the end portion. It was 2.9 times the total thickness of 45. As a result, the obtained laminate type secondary battery 1 had excellent airtightness.

In the embodiment described above, the manufacturing method of the laminate type secondary battery 1 is such that the heat bar 51 is brought into contact with the portion of the laminate outer package 40 housing the electrode body 5 where the outer package 41 is arranged to face. In this step, the heat bar 51 contacts the contact area CT1 located inside the peripheral edge ce of the laminated outer body 40. As shown in FIG. That is, the contact area CT1 is separated from the peripheral edge portion ce of the laminated exterior body 40 . Therefore, the heat bar 51 directly heats the sealant layer 45 positioned at the peripheral edge portion ce of the laminated outer body 40 , thereby preventing the melted sealant material from leaking out of the laminated outer body 40 . As a result, it is possible to effectively prevent the sealant material from adhering to the sealing device 50 such as the heat bar 51 . As a result, it is possible to continuously produce a large number of laminated secondary batteries 1 using the same heat bar 51, and the productivity of laminated secondary batteries 1 can be improved.

In one embodiment described above, the contact area is separated from the peripheral edge portion ce of the laminated outer body 40 by 0.5 mm or more. According to such an example, it is possible to sufficiently effectively prevent the melted sealant material from leaking out of the laminated exterior body 40 .

In the above-described embodiment, the method for manufacturing the laminated secondary battery 1 includes the step of welding the exterior materials 41 arranged facing each other by bringing the heat bar 51 into contact with the second contact region CT2 of the laminate exterior body 40. contains more. One edge EE2 in the longitudinal direction (width direction dy) of the second contact region CT2 is located within the contact region CT1, or one edge EE1 in the longitudinal direction (leading direction dx) of the contact region CT1 is It is located within the second contact area CT2. According to this example, a laminated secondary battery 1 having excellent airtightness can be produced. In addition, it is possible to reduce the size of the laminated outer package 40, and the energy density of the laminated secondary battery 1 can be improved.

In the above-described embodiment, the overlapping area OA between the contact area CT1 and the second contact area CT2 is the second contact area along the longitudinal direction of the contact area CT1 in the longitudinal direction (leading direction dx) of the contact area CT1. It has a length of 2/5 or more of the width W2 of CT2. In addition, the overlapping area OA has a length in the longitudinal direction (width direction dy) of the second contact area CT2 that is 2/5 or more of the width W1 of the contact area along the longitudinal direction of the second contact area CT2. there is According to such an example, the contact region CT1 and the second contact region CT2 can be overlapped with a sufficient size, and the laminated secondary battery 1 can be provided with excellent airtightness.

In the above-described embodiment, the laminated exterior body 40 has a linear welded portion MJ1 to which the facing exterior materials 41 are welded. The thickness of the welded portion MJ1 of the laminated outer body 40 is the portion located between the both end portions EP1 in the longitudinal direction (pull-out direction dx) of the welded portion MJ1 connected to the peripheral edge portion ce of the laminated outer body 40. It is thicker than OP and MP. According to the laminated exterior body 40 having such welded portions MJ1, it is possible to improve the sealing performance of the housing space RS. As a result, it is possible to effectively avoid leakage such as unexpected leakage of the electrolyte from the laminated outer package 40, thereby improving the reliability of the laminated secondary battery 1. FIG.

In the above-described embodiment, the total thickness of the sealant layer 45 at both end portions EP of the welded portion MJ1 of the laminated outer body 40 is a certain portion located between the both end portions EP of the welded portion MJ1 of the laminated outer body 40. It is more than twice the total thickness of the sealant layer 45 in OP and MP. According to the laminated outer body 40 having such a welded portion MJ1, it is possible to more effectively improve the sealing performance of the housing space RS.

In the above-described embodiment, the thickness of the laminated outer body 40 at the welded portions MJ1 is maximized at both end portions EP. According to the laminated outer body 40 having such a welded portion MJ1, it is possible to more effectively improve the sealing performance of the housing space RS.

In the above-described embodiment, the laminated exterior body 40 has a linear second welded portion MJ2 to which the exterior material 41 that extends linearly across the first welded portion MJ1 and is arranged to face each other is welded. further has The thickness of the laminated outer body 40 at the first welded portion MJ1 is greater than the thickness of the overlapped portion OP intersecting the second welded portion MJ2 at the end portion EP located between the overlapping portion OP and the peripheral edge portion ce of the laminated outer body 40. is thicker. According to the laminated exterior body 40 having such a first welded portion MJ1 and a second welded portion MJ2, it is possible to more effectively improve the sealing performance of the housing space RS.

12. The laminated secondary battery according to claim 11, wherein the thickness of said end portion of said laminated outer package is at least twice the thickness of said overlapping portion of said laminated outer package.
In the above-described embodiment, the thickness of the laminated outer body 40 at the end portion EP is at least twice the thickness of the laminated outer body 40 at the overlapping portion OP. According to the laminated exterior body 40 having such a first welded portion MJ1 and a second welded portion MJ2, it is possible to more effectively improve the sealing performance of the accommodation space RS.

Although one embodiment has been described with specific examples, these specific examples are not intended to limit one embodiment. The embodiment described above can be implemented in various other specific examples, and various omissions, replacements, and modifications can be made without departing from the spirit of the embodiment.

For example, in the specific example described above, an example in which the laminated exterior body 40 has one folded exterior material 41 is shown, but the present invention is not limited to this. The laminated exterior body 40 may have a first exterior material and a second exterior material that are arranged to face each other. In this example, when the laminated exterior body 40 has a rectangular shape in plan view, the housing space RS can be sealed by forming four welded portions in the laminated exterior body 40 . Each welded portion can be configured in the same manner as the first welded portion MJ1 in the example described above.

EXAMPLES The present invention will be described below with reference to Examples, but the following descriptions are not intended to limit the present invention.

In the same manner as in the manufacturing method described above, first, the second welded portion MJ2 and the third welded portion MJ3 are attached to the laminated outer body 40 in a state in which the electrode assembly 5 is sandwiched between the laminated outer body 40 formed by folding one sheet of the outer packaging material 41 . Next, after injecting an electrolytic solution into the laminated outer casing 40, the first welded portion MJ1 was formed in the laminated outer casing 40, whereby the laminated secondary battery 1 was manufactured. Conditions such as the heating temperature of the heat bar 51 , the pressure with which the heat bar 51 presses the laminated outer body 40 , the time at which the heat bar 51 presses the laminated outer body 40 , and the like are the normal conditions used in the manufacture of the laminated secondary battery 1 . Heat bars 51 having different total lengths were used in the comparative example and the working example. In Comparative Examples and Examples, the conditions were the same except for the length of the heat bar.

As shown in FIG. 15, the length of the laminated exterior body 40 along the pull-out direction dx was set to 509 mm. The second contact region CT2 with which the heat bar 51 is brought into contact when forming the second welded portion MJ2 has a width of 8 mm along the pull-out direction dx and is separated from the second edge e2 by 0.5 mm in the pull-out direction dx. and separated from the first edge e1 by 0.5 mm in the width direction dy. The third contact region CT3 with which the heat bar 51 is brought into contact when forming the third welded portion MJ3 has a width of 8 mm along the pull-out direction dx and is separated from the third edge e3 by 0.5 mm in the pull-out direction dx. and separated from the first edge e1 by 0.5 mm in the width direction dy.

The first contact area CT1 with which the heat bar 51 is brought into contact when forming the first welded portion MJ1 is centered with the laminated outer body 40 in the pull-out direction dx. The first contact region CT1 has a width of 8 mm along the width direction dy, and is separated from the first edge e1 by 0.5 mm in the width direction dy. Comparative Examples 1 and 2 used heat bars 51 having lengths of 514 mm and 539 mm, respectively. Therefore, in Comparative Examples 1 and 2, the first contact area CT1 has a length of 509 mm in the pull-out direction dx, and the heat bar 51 extends from the second edge e2 and the third edge e3 of the laminate body 40. was extending beyond. On the other hand, in Examples 1 to 3, heat bars 51 having lengths of 508 mm, 503 mm, and 498 mm were used, respectively. Therefore, in Examples 1 to 3, the first contact area CT1 has lengths of 508 mm, 503 mm and 498 mm along the extraction direction dx.

A large number of laminated secondary batteries 1 each having the second welded portion MJ2 and the third welded portion MJ3 formed thereon are prepared, and the same heat bar 51 is used in each case to continuously form the first welded portion MJ1. gone. In each example, the number of shots (the number of times of formation) at which the sealant material adheres to the heat bar 51 and the formation of the first welded portion MJ1 becomes difficult was confirmed.

In Examples 1 to 3, the first welded portion MJ1 was formed 20,000 times, but the sealant material did not adhere to the heat bar 51 . On the other hand, in Comparative Examples 1 and 2, it was necessary to clean the heat bar 51 every time the first welded portion MJ1 was formed ten times.

1 Laminated secondary battery 3 Tab 4 Sealing material 5 Electrode assembly 10 First electrode plate 10X Positive electrode plate 20 Second electrode plate 20Y Negative electrode plate 30 Insulator 40 Laminated exterior body 41 Exterior material 41A First part 41B Second part 42a Expansion Protruding portion 42b Collar portion 44 Metal layer 45 Sealant layer 50 Sealing device 51 Heat bar RS Housing space dz Stacking direction dx Pulling direction dy Width direction ce Peripheral edge e1 First edge e2 Second edge e3 Third edge e4 Fourth Edge MJ1 First welded part MJ2 Second welded part MJ3 Third welded part RP Folded part EP End part OP Overlapping part MP Central part CT1 First contact area EE1 End edge OE1 Outer edge IE1 Inner edge CT2 Second contact area EE2 End edge OE2 outer edge IE2 inner edge CT3 third contact area EE3 edge OE3 outer edge IE3 inner edge OA overlapping area

Claims (5)

A laminated exterior body formed using an exterior material including a metal layer and a sealant layer laminated on the metal layer;
an electrode body having a plurality of electrodes and housed in the laminate outer body,
The laminated exterior body has a linear welded portion to which exterior materials arranged to face each other are welded,
The thickness of the laminated outer body at the welded portion is thicker at both end portions in the longitudinal direction of the welded portion than at a portion located between the both end portions,
The total thickness of the sealant layer at both end portions of the welded portion of the laminated outer body is the total thickness of the sealant layer at a certain portion located between the both end portions of the welded portion of the laminated outer body. Laminated type secondary battery , which is more than twice as much as 2. The laminate type secondary battery according to claim 1 , wherein the welded portion is connected to the edge of the laminate outer package at the both end portions. 3. The laminated secondary battery according to claim 1, wherein the thickness of said laminated outer body at said welded portion is maximum at said end portions. The laminated exterior body further has a linear second welded portion to which exterior materials arranged linearly extending across the welded portion and facing each other are welded,
The thickness of the laminated outer body at the welded portion is thicker at the end portion located between the overlapping portion and the edge of the laminated outer body than at the overlapping portion intersecting the second welded portion. The laminated secondary battery according to any one of claims 1 to 3, wherein A laminated exterior body formed using an exterior material including a metal layer and a sealant layer laminated on the metal layer;
an electrode body having a plurality of electrodes and housed in the laminate outer body,
The laminated exterior body has a linear welded portion to which exterior materials arranged to face each other are welded,
The thickness of the laminated outer body at the welded portion is thicker at both end portions in the longitudinal direction of the welded portion than at a portion located between the both end portions,
The laminated exterior body further has a linear second welded portion to which exterior materials arranged linearly extending across the welded portion and facing each other are welded,
The thickness of the laminated outer body at the welded portion is thicker at the end portion located between the overlapping portion and the edge of the laminated outer body than at the overlapping portion intersecting the second welded portion. cage,
The laminated secondary battery , wherein the thickness of the end portion of the laminated outer package is at least twice the thickness of the overlapping portion of the laminated outer package.

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