Laminated secondary battery and method for manufacturing same

文档序号：863907 发布日期：2021-03-16 浏览：11次中文

阅读说明：本技术 层压型二次电池及其制造方法 (Laminated secondary battery and method for manufacturing same ) 是由吉冈浩也于 2019-09-26 设计创作，主要内容包括：本发明的层压型二次电池的制造方法包含：使容纳电极体(5)的层压外部包装体(40)的外部包装材料(41)对向配置的部分与加热棒(51)接触来对对向配置的外部包装材料(41)进行熔接的工序。加热棒与位于层压外部包装体的外周边缘部(ce)的内侧的接触区域(CT1)接触。(The method for manufacturing a laminated secondary battery of the present invention includes: and a step of welding the oppositely arranged outer packaging materials (41) by bringing the oppositely arranged parts of the outer packaging materials (41) of the laminated outer packaging body (40) containing the electrode body (5) into contact with a heating rod (51). The heating rod is in contact with a contact region (CT1) located inside the outer peripheral edge (ce) of the laminated outer packaging body.)

1. A method for manufacturing a laminated secondary battery, which is a method for manufacturing a laminated secondary battery having: a laminated exterior packaging body formed using an exterior packaging material comprising a metal layer and a sealant layer laminated on the metal layer, and an electrode body disposed within the laminated exterior packaging body,

the manufacturing method comprises: a step of bringing a heating rod into contact with a portion of the laminated exterior packaging body containing the electrode body, the portion being disposed opposite to the exterior packaging material, to weld the exterior packaging material disposed opposite to each other,

the heating rod is in contact with a contact area located inside the outer peripheral edge portion of the laminated outer package.

2. The method of manufacturing a laminated secondary battery according to claim 1, wherein,

the contact region is spaced from the outer peripheral edge of the laminated outer package by 0.5mm or more.

3. The method for manufacturing a laminated secondary battery according to claim 1 or 2, further comprising:

a step of welding the outer packaging materials arranged oppositely by contacting a heating rod with the 2 nd contact area of the laminated outer packaging body,

the end edge of one side of the 2 nd contact area in the length direction is positioned in the contact area, or the end edge of one side of the contact area in the length direction is positioned in the 2 nd contact area.

4. The method of manufacturing a laminated secondary battery according to claim 3, wherein,

an overlapping region of the contact region and the 2 nd contact region has a length in a longitudinal direction of the contact region of 2/5 or more of a width of the 2 nd contact region in the longitudinal direction of the contact region,

the overlap region has a length in the longitudinal direction of the 2 nd contact region of 2/5 or more of the width of the contact region in the longitudinal direction of the 2 nd contact region.

5. The method for manufacturing a laminated secondary battery according to any one of claims 1 to 4, further comprising:

a step of welding the outer packaging materials arranged oppositely by contacting a heating rod with the No. 3 contact area of the laminated outer packaging body,

the end edge of one side of the 3 rd contact area in the length direction is positioned in the contact area, or the end edge of the other side of the contact area in the length direction is positioned in the 3 rd contact area.

6. The method of manufacturing a laminated secondary battery according to claim 5, wherein,

the laminated outer package has a rectangular shape in plan view,

the contact region, the 2 nd contact region, and the 3 rd contact region respectively extend in a straight line along three edge portions of the rectangular shape that are different from each other.

7. A laminated secondary battery is provided with:

a laminated outer package formed using an outer package material comprising a metal layer and a sealant layer laminated on the metal layer, and

an electrode body having a plurality of electrodes and housed by the laminated exterior packaging body,

the laminated outer package has a linear welding part formed by welding outer package materials arranged oppositely,

the thickness of the laminated outer package at the weld is thicker at both end portions in the longitudinal direction of the weld than at a portion between the end portions.

8. The laminated secondary battery according to claim 7, wherein,

the welded portion is connected to an edge portion of the laminated outer package at the both end portions.

9. The laminated secondary battery according to claim 7 or 8, wherein,

the total thickness of the sealant layer at the both end portions of the welded portion of the laminated outer package is more than twice the total thickness of the sealant layer at a certain portion between the both end portions of the welded portion of the laminated outer package.

10. The laminated secondary battery according to any one of claims 7 to 9,

the thickness at the weld of the laminated outer package is maximized at the two end portions.

11. The laminated secondary battery according to any one of claims 7 to 10,

the laminated exterior packaging body further has: a linear 2 nd welding part intersecting the welding part and extending linearly and formed by welding the outer packaging materials arranged oppositely,

the thickness at the weld of the laminated outer wrap is thicker at the end portion between the repeating portion and the edge portion of the laminated outer wrap than at the repeating portion intersecting the 2 nd weld.

12. The laminated secondary battery according to claim 11, wherein,

a thickness at the end portion of the laminated exterior packaging body is more than twice a thickness at the repeated portion of the laminated exterior packaging body.

Technical Field

The present invention relates to a laminate type secondary battery and a method for manufacturing the laminate type secondary battery.

Background

In recent years, a laminate-type secondary battery manufactured by sealing a battery element (electrode body) with a laminate exterior package is widely used (for example, JP2014-517458A, JP2017-130374 a). A laminated outer package is generally produced, for example, using an outer package having a relatively thin metal layer of aluminum or the like and a sealant layer laminated on the metal layer. The laminated exterior package in which the battery element is sealed is obtained by folding back one sheet of exterior package material or by laminating two sheets of exterior package materials and heat-welding the exterior package materials arranged to face each other.

The outer wrappers arranged opposite to each other for forming the laminated outer package are arranged so that the sealant layers face each other. The sealant layer generally contains a resin having a thermoplastic property. The outer packaging material is heated by bringing a heating rod into contact with the outer packaging material, and the two opposing sealant layers are welded to join (seal) the two laminated outer packaging materials.

However, when the outer package material is welded using a heating rod, the molten sealant material may leak from the outer peripheral edge portion of the laminated outer package body and adhere to the heating rod. The sealant material attached to the heating rod is then attached to the laminated exterior packaging body as a processing object, contaminating the laminated exterior packaging body. In order to prevent such a problem, the sealant material attached to the heating rod needs to be removed every time. Such a cleaning operation of the heating rod significantly deteriorates the productivity of the laminate type secondary battery.

Disclosure of Invention

The present invention has been made in view of the above problems, and an object thereof is to improve productivity of a laminate type secondary battery.

A method for manufacturing a laminated secondary battery according to the present invention is a method for manufacturing a laminated secondary battery having: a laminated exterior packaging body formed using an exterior packaging material comprising a metal layer and a sealant layer laminated on the metal layer, and an electrode body disposed within the laminated exterior packaging body,

the heating rod is in contact with a contact area located inside the outer peripheral edge portion of the laminated outer package.

The method for manufacturing a laminated secondary battery according to the present invention may include: the contact region is spaced from the outer peripheral edge of the laminated outer package by 0.5mm or more.

The method for manufacturing a laminated secondary battery according to the present invention may include:

the manufacturing method further includes: a step of welding the outer packaging materials arranged oppositely by contacting a heating rod with the 2 nd contact area of the laminated outer packaging body,

The method for manufacturing a laminated secondary battery according to the present invention may include:

the overlap region has a length in the longitudinal direction of the 2 nd contact region of 2/5 or more of the width of the contact region in the longitudinal direction of the 2 nd contact region.

The method for manufacturing a laminated secondary battery according to the present invention may include:

the manufacturing method further includes: a step of welding the outer packaging materials arranged oppositely by contacting a heating rod with the No. 3 contact area of the laminated outer packaging body,

The method for manufacturing a laminated secondary battery according to the present invention may include:

the laminated outer package has a rectangular shape in plan view,

the contact region, the 2 nd contact region, and the 3 rd contact region respectively extend in a straight line along three edge portions of the rectangular shape that are different from each other.

The laminated secondary battery according to the present invention includes:

a laminated outer package formed using an outer package material comprising a metal layer and a sealant layer laminated on the metal layer, and

an electrode body having a plurality of electrodes and housed by the laminated exterior packaging body,

the laminated outer package has a linear welding part formed by welding outer package materials arranged oppositely,

the thickness of the laminated outer package at the weld is thicker at both end portions in the longitudinal direction of the weld than at a portion between the end portions.

In the laminated secondary battery according to the present invention, there may be: the welded portion is connected to an edge portion of the laminated outer package at the both end portions.

In the laminated secondary battery according to the present invention, there may be: the total thickness of the sealant layer at the both end portions of the welded portion of the laminated outer package is more than twice the total thickness of the sealant layer at a certain portion between the both end portions of the welded portion of the laminated outer package.

In the laminated secondary battery according to the present invention, there may be: the thickness at the weld of the laminated outer package is maximized at the two end portions.

In the laminated secondary battery according to the present invention, there may be:

In the laminated secondary battery according to the present invention, there may be: a thickness at the end portion of the laminated exterior packaging body is more than twice a thickness at the repeated portion of the laminated exterior packaging body.

The present invention can improve the productivity of a laminate type secondary battery by suppressing the adhesion of a sealant material to a heating rod.

Drawings

Fig. 1 is a diagram for explaining an embodiment of the present invention, and is a perspective view showing a laminate type secondary battery.

Fig. 2 is a perspective view showing the interior of the laminated secondary battery of fig. 1 with the laminated exterior package, the insulator, and the like removed.

Fig. 3 is a vertical sectional perspective view for explaining a stacked structure of an electrode plate and an insulator of the laminate type secondary battery of fig. 1.

Fig. 4 is a plan view showing an electrode plate and an insulator of the laminate-type secondary battery of fig. 1.

Fig. 5 is a longitudinal sectional view showing a cross section of the laminate-type secondary battery of fig. 1 in a width direction.

Fig. 6 is a partial longitudinal sectional view showing a section of the laminated secondary battery of fig. 1 in a taking-out direction.

Fig. 7 is a plan view of the laminate type secondary battery of fig. 1, illustrating a contact region and a welded portion by a heating rod.

Fig. 8 is a view for explaining a method of manufacturing the laminated secondary battery of fig. 1, which is a sectional view showing a step of forming a welded portion.

Fig. 9 is an enlarged view of fig. 7, which is a view for explaining a positional relationship between the 1 st contact region and the 2 nd contact region.

Fig. 10 is a diagram corresponding to fig. 9, and is a diagram for explaining a modification of the positional relationship between the 1 st contact region and the 2 nd contact region.

Fig. 11 is a view corresponding to fig. 9, which is a view for explaining another modification of the positional relationship between the 1 st contact region and the 2 nd contact region.

Fig. 12 is a view corresponding to fig. 9, and is a view for explaining another modification of the positional relationship between the 1 st contact region and the 2 nd contact region.

Fig. 13 is a diagram corresponding to fig. 9, and is a diagram for explaining another modification of the positional relationship between the 1 st contact region and the 2 nd contact region.

Fig. 14 is a sectional view taken along the line XIV-XIV of fig. 9, which is a view for explaining the thickness of the laminated exterior packaging body.

Fig. 15 is a plan view schematically showing a laminated secondary battery of an example.

Fig. 16 is a view corresponding to fig. 8, and is a view for explaining a conventional method for manufacturing a laminate-type secondary battery.

Detailed description of the invention

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, the appropriate scale, the horizontal/vertical dimension ratio, and the like may be changed or exaggerated based on the actual object for the convenience of understanding.

Fig. 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: the laminated exterior package 40, the electrode body 5 contained in the laminated exterior package 40, and the tab 3 connected to the electrode body 5 and protruding from the inside to the outside of the laminated exterior package 40. In which the laminated outer package 40 is formed by welding the peripheries of the outer packages 41 arranged to face each other. That is, the laminated exterior package 40 is provided with: the outer packaging material 41 has fusion joints MJ1, MJ2, and MJ3 formed by fusion (bonding) of two opposing portions 41A and 41B. The tab 3 extends from the inside to the outside of the laminated outer package 40 through between the two portions 41A and 41B of the outer package 41. The electrode body 5 has: the electrode plate 10 and the electrode plate 20 of the 1 st electrode and the electrode plate 20 of the 2 nd electrode are alternately laminated, and the insulator 30 is positioned between the electrode plate 10 of the 1 st electrode and the electrode plate 20 of the 2 nd electrode.

In the following, an example in which the laminated secondary battery 1 constitutes a laminated lithium ion secondary battery will be described. In this example, the 1 st electrode plate 10 constitutes a positive electrode plate 10X, and the 2 nd electrode plate 20 constitutes a negative electrode plate 20Y. However, as is apparent from the description of the operational effects described below, the embodiment described herein is applicable not only to lithium-ion secondary batteries but also to secondary batteries other than lithium-ion secondary batteries, and is applicable not only to stacked secondary batteries but also to wound secondary batteries. That is, the present embodiment can be widely applied to the laminated secondary battery 1 in which the electrode body 5 is accommodated in the laminated exterior package 40.

First, the structure of the laminated exterior package 40 will be described. The laminated exterior packaging body 40 is a packaging material for sealing the electrode body 5. As shown in fig. 1, 5 and 6, the laminated exterior packaging body 40 has exterior packaging materials 41 arranged facing each other. The laminated outer package 40 may include two separate pieces of the outer package 41, or may include, as in the illustrated example, the 1 st portion 41A and the 2 nd portion 41B of the outer package 41 in which one piece of the outer package 41 is folded back and opposed to each other. The outer package 41 has a metal layer 44 and a sealant layer 45 laminated on the metal layer 44 (see fig. 5 and 6). The metal layer 44 preferably has high gas barrier properties and formability.

The material of the metal layer 44 is not particularly limited as long as it can prevent moisture from entering from the outside and improve the strength of the entire laminated secondary battery, and from the viewpoint of moisture barrier properties, weight, and cost, there can be used: the known metals, metal oxides, metal nitrides, and alloys thereof are preferably aluminum, aluminum alloys, stainless steel, and the like, and aluminum is particularly preferably used. When the strength of the entire battery can be ensured, a metal layer may be provided by vapor deposition, sputtering, or the like instead of the metal foil.

The sealant layer 45 has an insulating property, and prevents short-circuiting between the metal layer 44 and the electrode plates 10 and 20 accommodated in the laminated exterior package 40. The sealant layer 45 has not only insulating properties but also thermoplastic properties (adhesiveness). The 1 st part 41A and the 2 nd part 41B of the outer package 41 are laminated so that the sealant layers 45 face each other. In the outer peripheral edge ce of the laminated exterior packaging body 40, the 1 st portion 41A and the 2 nd portion 41B of the exterior packaging material 41 are welded to each other except for the folded-back portion RP where the exterior packaging material 41 is folded back. Further, between the 1 st part 41A and the 2 nd part 41B of the exterior packaging material 41, an accommodating space RS of the electrode body 5 is formed. The exterior package 40 is laminated, and the electrode body 5 and the electrolytic solution are sealed in the housing space RS thereof. The sealant layer 45 is preferably chemically resistant because it is also in contact with the electrolyte. As a material of such a sealant layer 45, a polyolefin-based resin, specifically, polypropylene, modified polypropylene, low-density polypropylene, ionomer, ethylene vinyl acetate, can be used.

In the illustrated example, the 1 st part 41A of the exterior packaging material 41 is a plate-like member. On the other hand, the 2 nd portion 41B of the outer wrapper 41 is formed in a cup shape. The 2 nd part 41B has: a cup-shaped bulging portion 42a, and a flange portion 42b connected to the bulging portion 42 a. The flange portion 42b circumferentially surrounds the expanded portion 42a and is connected to the periphery of the expanded portion 42 a. The flange portion 42B is welded to the 2 nd portion 41B so as to seal the accommodation space RS between the 1 st portion 41A and the 2 nd portion 41B. The bulging portion 42a may be manufactured by, for example, drawing, or may be a portion of the flexible outer package 41 that is deformed by the electrode body 5.

However, not limited to the above example, the laminated outer packaging body 40 may have two sheets of outer packaging material. The two sheets of the outer cover material may be welded circumferentially at a position to be the outer peripheral edge ce of the laminated outer cover 40, thereby forming the sealed accommodation space RS.

The tab 3 functions as a terminal in the laminated secondary battery 1. The positive electrode plate 10X (the 1 st electrode plate 10) of the electrode body 5 is electrically connected to one tab 3, and the negative electrode plate 20Y (the 2 nd electrode plate 20) of the electrode body 5 is electrically connected to the other tab 3. The tab 3 may be formed using aluminum, nickel-plated copper, or the like. A pair of lugs project from the inside of the laminated outer package 40 to the outside of the laminated outer package 40. In the illustrated example, the tab 3 extends from the electrode body 5 in the lead-out direction dx out of the laminated exterior packaging body 40.

Between the laminated exterior package 40 and the tab 3, sealing is performed in a region where the tab 3 protrudes. Specifically, as shown in fig. 1 and 6, the sealing material 4 is provided between the tab 3 and the laminated exterior package 40. The sealing material 4 seals the space between the tab 3 and the laminated exterior package 40, and seals the housing space RS of the laminated exterior package 40. The sealing material 4 has adhesiveness and bonds the tab 3 and the laminated exterior package 40. As shown in fig. 6, the sealing material 4 is provided on both sides of the tab 3 in the stacking direction dz of the electrode plates 10 and 20.

As shown in fig. 7, in the laminated secondary battery 1 shown in the figure, the laminated exterior packaging body 40 has a rectangular shape in a plan view. The illustrated laminated exterior package 40 has a longitudinal direction in a lead-out direction dx in which the tab 3 projects, and a width direction in a width direction dy perpendicular to the lead-out direction dx. Therefore, the laminated exterior package 40 includes, as the outer peripheral edge ce: a pair of long edge portions (1 st edge portion e1 and 4 th edge portion e4) parallel to the lead-out direction dx, and a pair of short edge portions (2 nd edge portion e2 and 3 rd edge portion e3) parallel to the width direction dy. Here, the 4 th edge portion e4 is a folded portion RP where the exterior packaging material 41 is folded back. Further, the laminated exterior packaging body 40 has: the 1 st welded part MJ1 extending linearly along the 1 st edge portion e1, the 2 nd welded part MJ2 extending linearly along the 2 nd edge portion e2, and the 3 rd welded part MJ3 extending linearly along the 3 rd edge portion e 3. The outer wrappers 41 arranged facing each other are welded to the respective welded portions MJ1, MJ2, and MJ 3. The 2 nd weld MJ2 is connected in both end portions thereof with the 1 st weld MJ1 and the fold back RP. Likewise, the 3 rd fusion MJ3 is connected at both ends thereof with the 1 st fusion MJ1 and the fold back RP. The accommodating space RS is divided and sealed by the fusion portions MJ1, MJ2, MJ3 and the folded portion RP.

Next, the electrode body 5 will be described while mainly referring to specific examples shown in the drawings. The electrode body 5 has: a positive electrode plate 10X (1 st electrode plate 10) and a negative electrode plate 20Y (2 nd electrode plate 20), and an insulator 30 located between the positive electrode plate 10X and the negative electrode plate 20Y. First, positive electrode plate 10X and negative electrode plate 20Y will be described.

As shown in fig. 2, 3, 5, and 6, the electrode body 5 has a plurality of positive electrode plates 10X (1 st electrode plates 10) and negative electrode plates 20Y (2 nd electrode plates 20). The positive electrode plate 10X (1 st electrode plate 10) and the negative electrode plate 20Y (2 nd electrode plate 20) are contained in one laminated exterior package 40, for example, 10 or more pieces each, 15 or more pieces each, or 20 or more pieces each. The positive electrode plates 10X and the negative electrode plates 20Y are alternately arranged in the stacking direction dz. The electrode body 5 and the laminated secondary battery 1 have a flat shape as a whole, are thin in the stacking direction dz, and expand in the leading direction dx and the width direction dy perpendicular to the stacking direction dz.

In order to clarify the directional relationship between the drawings, the derivation direction dx, the width direction dy, and the stacking direction dz are shown in common directions between the drawings in the several drawings.

In the non-limiting example shown, positive plate 10X and negative plate 20Y have an oblong outer contour. The positive electrode plate 10X and the negative electrode plate 20Y have a longitudinal direction in a lead-out direction dx perpendicular to the stacking direction dz, and have a width direction in a width direction dy perpendicular to both the stacking direction dz and the lead-out direction dx. As shown in fig. 2 and 4, positive electrode plate 10X and negative electrode plate 20Y are arranged offset in lead-out direction dx. More specifically, the plurality of positive electrode plates 10X are disposed closer to one side (lower left side in fig. 2 and left side in fig. 4) in the lead-out direction dx, and the plurality of negative electrode plates 20Y are disposed closer to the other side (upper right side in fig. 2 and right side in fig. 4) in the lead-out direction dx. The positive electrode plate 10X and the negative electrode plate 20Y overlap each other at the center in the lead-out direction dx in the stacking direction dz. In fig. 2, the insulator 30 is not shown.

The positive electrode plate 10X (1 st electrode plate 10) has a sheet-like outer shape as shown in the drawing. The positive electrode plate 10X (1 st electrode plate 10) has: a positive electrode collector 11X (the 1 st electrode collector 11), and a positive electrode active material layer 12X (the 1 st electrode active material layer 12) provided on the positive electrode collector 11X. In the lithium ion secondary battery, the positive electrode plate 10X releases lithium ions during discharge and stores lithium ions during charge.

The positive electrode collector 11X has a1 st surface 11a and a2 nd surface 11b facing each other as main surfaces. The positive electrode active material layer 12X is formed on at least one of the 1 st surface 11a and the 2 nd surface 11b of the positive electrode current collector 11X. Specifically, when the 1 st surface 11a or the 2 nd surface 11b of the positive electrode 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 active material layer 12X is not provided on the surface that is the outermost side of the positive electrode collector 11X. The plurality of positive electrode plates 10X included in the laminate-type secondary battery 1 may have the positive electrode active material layers 12X on both sides of the positive electrode collector 11X and be set to the same configuration as each other, except for the presence or absence of the positive electrode active material layers 12X depending on the position of the positive electrode collector 11X.

The positive electrode current collector 11X and the positive electrode active material layer 12X can be produced by various production methods using various materials applicable to the laminate type secondary battery 1 (lithium ion secondary battery). As one example, the positive electrode collector 11X may be formed of aluminum foil. The positive electrode active material layer 12X contains, for example, a positive electrode active material, a conductive auxiliary agent, and a binder serving as a binder. The positive electrode active material layer 12X can be prepared by: a slurry for a positive electrode, in which a positive electrode active material, a conductive assistant, and a binder are dispersed in a solvent, is applied to a material serving as the positive electrode current collector 11X and cured. As the positive electrode active material, for example, a lithium metalate compound represented by a general formula LiMxOy (where M is a metal, and x and y are a composition ratio of the metal M and oxygen O) is used. Specific examples of the lithium metal oxide compound include lithium cobaltate, lithium nickelate, lithium manganate and the like. As the conductive assistant, acetylene black or the like can be used. As the binder, polyvinylidene fluoride or the like can be used.

As shown in fig. 4, the positive electrode collector 11X (the 1 st electrode collector 11) has a1 st end region a1 and a1 st electrode region b 1. The positive electrode active material layer 12X (the 1 st electrode active material layer 12) is disposed only in the 1 st electrode region b1 of the positive electrode collector 11X. The 1 st end region a1 and the 1 st electrode region b1 are aligned in the lead-out direction dx. The 1 st end region a1 is located more outside (left side in fig. 4) in the lead-out direction dx than the 1 st electrode region b 1. As shown in fig. 6, the plurality of positive electrode collectors 11X are joined and electrically connected to the 1 st end region a1 by resistance welding, ultrasonic welding, tape bonding, welding, or the like. In the illustrated example, one tab 3 is electrically connected to the positive electrode collector 11X in the 1 st end region a 1. The tab 3 extends from the electrode body 5 in the direction dx. On the other hand, as shown in fig. 4, the 1 st electrode region b1 is located in a region facing the negative electrode active material layer 22Y of the negative electrode plate 20Y, which will be described later. As shown in fig. 5, the width of positive electrode plate 10X in width direction dy is smaller than the width of negative electrode plate 20Y in width direction dy. With the arrangement of the 1 st electrode region b1, lithium can be prevented from being deposited from the positive electrode active material layer 12X.

Next, the negative electrode plate 20Y (2 nd electrode plate 20) will be described. The negative electrode plate 20Y also has a sheet-like outer shape, as in the positive electrode plate 10X. The negative electrode plate 20Y (the 2 nd electrode plate 20) has: a negative electrode current collector 21Y (the 2 nd electrode current collector 21), and a negative electrode active material layer 22Y (the 2 nd electrode active material layer 22) provided on the negative electrode current collector 21Y. In the lithium ion secondary battery, the negative electrode plate 20Y stores lithium ions during discharge and releases lithium ions during charge.

The negative electrode current collector 21Y has a1 st surface 21a and a2 nd surface 21b facing each other as main surfaces. The anode active material layer 22Y is formed on at least one of the 1 st surface 21a and the 2 nd surface 21b of the anode current collector 21Y. Specifically, when the 1 st surface 21a or the 2 nd surface 21b of the negative electrode collector 21Y 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 negative electrode active material layer 22Y is not provided on the outermost surface of the negative electrode collector 21Y. The plurality of negative electrode plates 20Y included in the laminate-type secondary battery 1 may have the negative electrode active material layers 22Y on both sides of the negative electrode collector 21Y and be set to the same configuration as each other, except for the presence or absence of the negative electrode active material layer 22Y depending on the position of the negative electrode collector 21Y.

The anode current collector 21Y and the anode active material layer 22Y can be prepared by various methods using various materials applicable to the laminate type secondary battery 1 (lithium ion secondary battery). As an example, the negative electrode collector 21Y may be formed of, for example, a copper foil. The negative electrode active material layer 22Y contains, for example, a negative electrode active material containing a carbon material and a binder functioning as a binder. The anode active material layer 22Y, for example, may be prepared by: a slurry for a negative electrode obtained by dispersing a negative electrode active material including carbon powder, graphite powder, or the like and a binder such as polyvinylidene fluoride in a solvent is applied to a material to be the negative electrode current collector 21Y and cured.

As shown in fig. 4, the negative electrode collector 21Y (the 2 nd electrode collector 21) has a2 nd end region a2 and a2 nd electrode region b 2. The anode active material layer 22Y (the 2 nd electrode active material layer 22) is disposed in the 2 nd electrode region b2 of the anode current collector 21Y. The 2 nd end region a2 and the 2 nd electrode region b2 are aligned in the lead-out direction dx. The 2 nd end region a2 is located more outside in the lead-out direction dx than the 2 nd electrode region b2 (on the right side in fig. 4). The plurality of negative electrode collectors 21Y are joined and electrically connected to the 2 nd end region a2 by resistance welding, ultrasonic welding, tape bonding, welding, or the like. One tab 3 is electrically connected to the negative electrode collector 21Y in the 2 nd end region a 2. The tab 3 extends from the electrode body 5 in the direction dx.

As described above, the 1 st electrode region b1 of the positive electrode plate 10X is located inside the region facing the 2 nd electrode region b2 of the negative electrode plate 20Y (see fig. 4). That is, the 2 nd electrode region b2 is expanded in a region including a region facing the positive electrode active material layer 12X of the positive electrode plate 10X. As shown in fig. 5, the negative electrode plate 20Y has a width in the width direction dy greater than that of the positive electrode plate 10X.

Next, the insulator 30 will be explained. The insulator 30 is located between the positive electrode plate 10X (1 st electrode plate 10) and the negative electrode plate 20Y (2 nd electrode plate 20). The insulator 30 prevents a short circuit caused by contact of the positive electrode plate 10X (1 st electrode plate 10) and the negative electrode plate 20Y (2 nd electrode plate 20). The insulator 30 preferably has: a large ion permeability (air permeability), a given mechanical strength, and durability to an electrolytic solution, a positive electrode active material, a negative electrode active material, and the like. As the insulator 30, for example, a porous body made of an insulating material, a nonwoven fabric, or the like can be used. The laminated exterior package 40 encloses an electrolyte together with the electrode body 5. The electrolyte solution is impregnated into the insulator 30 made of a porous material or nonwoven fabric, whereby the electrode active material layers 12 and 22 of the electrode plates 10 and 20 are kept in contact with the electrolyte solution.

In the illustrated example, a single insulator 30 is located between any two electrode plates 10 and 20 adjacent to each other in the stacking direction dz. The insulator 30 is a bendable sheet member. The insulator 30 has a1 st surface 30a and a2 nd surface 30b as a pair of main surfaces opposed to each other. As shown in fig. 3 and 5, insulators 30 are alternately folded back in the opposite directions in width direction dy, and extend between positive electrode plates 10X and negative electrode plates 20Y adjacent to each other in stacking direction dz in this order. The insulator 30 has: the 1 st folded portion 31 folded back on one side in the width direction dy, and the 2 nd folded portion 32 folded back on the other side opposite to the one side in the width direction dy. That is, the insulator 30 is formed in a U-folded shape. However, in the present embodiment, the insulator 30 does not necessarily have to have a U-folded shape, and the single-sheet insulator 30 may be disposed between the positive electrode plate 10X (1 st electrode plate 10) and the negative electrode plate 20Y (2 nd electrode plate 20) to insulate the positive electrode plate 10X (1 st electrode plate 10) and the negative electrode plate 20Y (2 nd electrode plate 20).

As shown in fig. 4, in a plan view, insulator 30 is expanded so as to cover the entire region of positive electrode active material layer 12X of positive electrode plate 10X. Therefore, as shown in fig. 5, the width of the insulator 30 in the width direction dy is larger than the width of the positive electrode plate 10X in the width direction dy. The length of the insulator 30 in the lead-out direction dx is longer than the length of the positive electrode active material layer 12X in the lead-out direction dx.

Similarly, as shown in fig. 4, in a plan view, the insulator 30 is expanded 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 larger than the width of the negative electrode plate 20Y in the width direction dy. The length of the insulator 30 in the lead-out direction dx is longer than the length of the negative electrode active material layer 22Y in the lead-out direction dx.

As the insulator 30, a resin porous film is used. More specifically, as the insulator 30, a porous film containing a thermoplastic resin having a melting point of about 80 to 140 ℃ can be used. As the thermoplastic resin, polyolefin resin such as polypropylene and polyethylene can be used.

Further, the insulator 30 may have: the substrate layer, the functional layer of stromatolite on the substrate layer. With this configuration, the 1 st surface 30a of the insulator 30 facing the positive electrode plate 10X and the 2 nd surface 30b of the insulator 30 facing the negative electrode plate 20Y can have different properties. For example, the negative electrode plate 20Y having a large area and allowing easy drying of the electrolyte may be opposed to the functional layer having a large porosity, and the positive electrode plate 10X may be opposed to the base layer. In another example, positive electrode plate 10X, which is likely to be heated, may be opposed to a functional layer having excellent heat resistance, and negative electrode plate 20Y may be opposed to a base material layer. As the substrate layer, for example, the resin porous film described immediately above can be used. As the functional layer, for example, a layer containing an inorganic material can be used. The inorganic material can impart excellent heat resistance, for example, heat resistance of 150 ° or more, to the functional layer. Examples of such inorganic materials include: cellulose and its modification, polyolefin, polyethylene terephthalate, polybutylene terephthalate, polypropylene, polyester, polyacrylonitrile, aromatic polyamide, polyamide imide, polyimide and other fibrous or particulate materials, and by using such inorganic materials, the functional layer can be provided with a higher porosity than the substrate layer.

Next, a method for manufacturing the laminated secondary battery 1 having the above-described configuration will be described.

First, an electrode body 5 is prepared in which a positive electrode plate 10X and a negative electrode plate 20Y are laminated with an insulator 30 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 may be prepared by the materials and the manufacturing method. Next, the prepared positive electrode plate 10X, negative electrode plate 20Y, and insulator 30 are laminated in such a manner that the insulator 30 is located between the positive electrode plate 10X and the negative electrode plate 20Y. Thereby, the electrode body 5 was obtained. Then, the positive electrode collectors 11X of the plurality of positive electrode plates 10X are electrically connected to each other, and at the same time, are electrically connected to the tab 3. Also, the negative electrode collectors 21Y of the plurality of negative electrode plates 20Y are electrically connected to each other and, at the same time, to the tab 3.

Next, the exterior material 41 for constituting the laminated exterior package 40 is prepared. By folding back the exterior packaging material 41 at the folded-back portion RP, the 1 st part 41A and the 2 nd part 41B of the exterior packaging material 41 are opposed to each other. In the folded-back outer package 41, the sealant layer 45 is located inside. Next, the electrode body 5 is disposed between the 1 st part 41A and the 2 nd part 41B. At this time, as shown in fig. 7, each tab 3 protrudes from between the 1 st part 41A and the 2 nd part 41B of the 1 st outer wrapping 41.

In the region to be the 2 nd part 41B of the outer cover 41, the bulge 42a may be formed in advance by, for example, drawing. In this example, the electrode body 5 is accommodated in the expanded portion 42 a.

Next, the 1 st part 41A and the 2 nd part 41B of the exterior packaging material 41 are welded at a position surrounding the bulging portion 42a from three sides in a state where the electrode body 5 is arranged between the 1 st part 41A and the 2 nd part 41B of the exterior packaging material 41. In the illustrated example, three welded portions MJ1 MJ3 are formed in sequence by welding the 1 st part 41A and the 2 nd part 41B facing each other.

The 1 st weld MJ1 is formed along the 1 st edge portion e1 of the laminated outer package 40. The 1 st fusion MJ1 extends linearly in the lead-out direction dx. In the illustrated example, the 1 st weld MJ1 is connected to a pair of edge portions of the laminated outer package 40 facing in the lead-out direction dx, i.e., the 2 nd edge portion e2 and the 3 rd edge portion e 3.

The 2 nd weld MJ2 is formed along the 2 nd edge portion e2 of the laminated outer package 40. The 2 nd fusion joint MJ2 extends linearly in the width direction dy. In the illustrated example, the 2 nd welding MJ2 is connected to a pair of edge portions of the laminated outer package 40 facing in the width direction dy, i.e., the 1 st edge portion e1 and the 4 th edge portion e 4. Also, a 3 rd weld MJ3 is formed along the 3 rd edge portion e3 of the laminated outer package 40. The 3 rd welded part MJ3 extends linearly in the width direction dy. In the illustrated example, the 3 rd welded portion MJ3 is connected to a pair of edge portions of the laminated outer package 40 facing in the width direction dy, i.e., the 1 st edge portion e1 and the 4 th edge portion e 4.

The order of forming the three welds MJ1 to MJ3 is not particularly limited. In addition, the 2 nd welding part MJ2 and the 3 rd welding part MJ3 are not connected to each other, and thus may be simultaneously formed. Further, when the final welded portion is formed, the electrolyte is contained in the containing space RS of the laminated outer package 40 closed on three sides. As an example, the 2 nd welding MJ2 and the 3 rd welding MJ3 may be prepared sequentially or simultaneously, and then, the electrolyte may be filled in the laminated outer package 40, and then, the 1 st welding MJ1 may be prepared.

As shown in fig. 8, the welded portions MJ1 to MJ3 are formed using a sealing device 50 having a heating rod 51 as a rod-shaped heating member. The sealant layers 45 of the 1 st part 41A and the 2 nd part 41B are melted and then cured by pressing the pair of heated heating rods 51 against the outer packaging material 41 from both sides, thereby welding the 1 st part 41A and the 2 nd part 41B. In the 2 nd fusion-bonded part MJ2 and the 3 rd fusion-bonded part MJ3, the exterior packaging material 41 is provided at the tab 3, and the sealing material 4 is fused to the exterior packaging material 41 to seal between the tab 3 and the exterior packaging material 41. In forming the respective fusion joints MJ1 to MJ3, other heating rods 51 having lengths corresponding to the respective fusion joints may be used.

In addition, as shown in fig. 16, when the exterior packaging material 141 is welded using the heating rod 151, the melted sealant material 146 may leak from the outer peripheral edge ce of the laminated exterior packaging body 140 and adhere to the heating rod 151 in some cases. The sealant material 146 attached to the heating rod 151 is then attached to the laminated exterior packaging body 140 as a processing object, and contaminates the laminated exterior packaging body 140. To avoid such a problem, the sealant material 146 attached to the heating rod 151 needs to be removed every time. Such a cleaning operation of the heating rod 151 significantly deteriorates the productivity of the laminate-type secondary battery 101.

Conventionally, in order to reliably weld the outer wrappers 141 arranged opposite to each other, it is necessary to press the heating rod 151 to the entire length of the width of the portion to be welded and heat-press it. Therefore, when the welded portion is formed over the entire width of the outer wrapper 41, the entire length of the heating rod 151 is set to be sufficiently longer than the entire width of the outer wrapper 141 as shown in fig. 16. By using the heating rod 151 longer than the full width of the outer packaging material 141, the sealant layer 145 laminated on the metal layer 144 can be melted in the region including the full width of the outer packaging material 41. On the other hand, the melted sealant 146 overflows from the outer peripheral edge ce of the laminated outer package 140 and adheres to the heating rod 151.

Therefore, in the present embodiment, as shown in fig. 7 and 8, the outer peripheral edge ce of the laminated exterior packaging body 40 where the sealant material may overflow is not brought into contact with the heating rod 51. By this embodiment, productivity can be improved. Further, in the laminated secondary battery 1 produced by the method based on the present embodiment, it is possible to weld the exterior packaging material 41 more strongly and improve the sealability of the housing space RS. Such an effect significantly exceeds the range of measurement by the conventional technical standards.

In the illustrated example, the heating rod 51 is brought into contact with the 2 nd contact region CT2 and heated and pressed while forming the 2 nd fusion part MJ 2. The 2 nd contact region CT2 extends linearly along the 2 nd edge portion e2 of the laminated outer package 40. The 2 nd contact region CT2 includes a pair of edges EE2 and EE2 facing in the width direction dy, an outer edge OE2 and an inner edge IE2 facing in the lead-out direction dx. One end edge EE2 is located in the vicinity of the 1 st edge e1 and extends parallel to the lead-out direction dx along the 1 st edge e 1. The other end edge EE2 is located near the 4 th edge e4 and extends parallel to the lead-out direction dx along the 4 th edge e 4. The inner edge IE2 is closer to the receiving space RS than the outer edge OE 2. The outer edge OE2 is closer to the 2 nd edge e2 than the inner edge IE 2. The outer side edge OE2 and the inner side edge IE2 extend along the 2 nd edge portion e2 in parallel with the width direction dy.

In forming the 3 rd welded part MJ3, the heating rod 51 is brought into contact with the 3 rd contact region CT3 and heated and pressed. The 3 rd contact region CT3 extends linearly along the 3 rd edge portion e3 of the laminated outer package 40. The 3 rd contact region CT3 includes: a pair of end edges EE3, EE3 facing in the width direction dy, an outer edge OE3 and an inner edge IE3 facing in the lead-out direction dx. One end edge EE3 is located in the vicinity of the 1 st edge e1 and extends parallel to the lead-out direction dx along the 1 st edge e 1. The other end edge EE3 is located near the 4 th edge e4 and extends parallel to the lead-out direction dx along the 4 th edge e 4. The inner edge IE3 is closer to the receiving space RS than the outer edge OE 3. The outer edge OE3 is closer to the 3 rd edge portion e3 than the inner edge IE 3. The outer side edge OE3 and the inner side edge IE3 extend along the 3 rd edge portion e3 in parallel with the width direction dy.

When the 1 st welded part MJ1 is formed, the heating rod 51 is brought into contact with the 1 st contact region CT1 and heated and pressed. The 1 st contact region CT1 extends linearly along the 1 st edge portion e1 of the laminated outer package 40. The 1 st contact region CT1 includes: a pair of end edges EE1, EE1 facing in the lead-out direction dx, an outer edge OE3 and an inner edge IE3 facing in the width direction dy. One end edge EE1 is located in the vicinity of the 2 nd edge portion e2 and extends parallel to the width direction dy along the 2 nd edge portion e 2. The other end edge EE1 is located near the 3 rd edge portion e3 and extends parallel to the width direction dy along the 3 rd edge portion e 3. The inner edge IE1 is closer to the receiving space RS than the outer edge OE 1. The outer edge OE1 is closer to the 1 st edge portion e1 than the inner edge IE 1. The outer edge OE13 and the inner edge IE1 extend along the 1 st edge portion e1 parallel to the lead-out direction dx.

That is, the 1 st contact region CT1, the 2 nd contact region CT2, and the 3 rd contact region CT3 are separated from the outer peripheral edge ce of the laminated outer package 40 and are located inside the outer peripheral edge ce of the laminated outer package 40.

In this way, by enclosing the region where the heater rod 51 and the outer wrapper 41 are in contact with each other in the outer peripheral edge ce of the laminated outer wrapper 40, the melted sealant can be effectively prevented from leaking from the outer peripheral edge ce of the laminated outer wrapper 40. Therefore, adhesion of the melted sealant material to the heating rod 51 can be effectively avoided, and the productivity of the laminate-type secondary battery 1 can be effectively improved.

In the illustrated example, the 4 th edge portion e4 of the laminated outer package 40 is a folded portion RP formed by folding back the outer package material 41. Therefore, the melted sealant material does not leak from the 4 th edge portion e 4. Thus, the 2 nd and 3 rd contact regions CT2 and CT3 may intersect the 4 th edge portion e4, and the other side end edges EE2, EE3 may be located on the 4 th edge portion e 4.

From the viewpoint of avoiding leakage of the sealant material from the outer peripheral edge ce of the laminated exterior package 40, the contact regions CT1, CT2, CT3 are preferably 0.5mm or more from the outer peripheral edge ce of the laminated exterior package 40. By setting this distance to 0.5mm or more, it is possible to effectively prevent the melted sealant material from leaking from the outer peripheral edge ce of the laminated exterior package 40 under the normal welding conditions of the laminated exterior package 40 in the production of the laminated secondary battery 1. For example, in the case of referring to the 1 st contact region CT1, the separation distance L1x (see fig. 9) in the lead-out direction dx between the end edge EE1 on the 1 st contact region CT1 side and the 2 nd edge e2 is preferably 0.5mm or more. The separation distance in the lead-out direction dx between the outer edge EE1 and the 3 rd edge e3 of the 1 st contact region CT1 is preferably 0.5mm or more. The separation distance L1y (see fig. 9) in the width direction dy between the outer edge OE1 and the 1 st edge portion e1 of the 1 st contact region CT1 is preferably 0.5mm or more.

As shown in fig. 7, the 1 st contact region CT1 is preferably contiguous with (overlaps) the 2 nd contact region CT 2. In this case, the 1 st fusion joint MJ1 formed by the heating rod 51 contacting the 1 st contact region CT1 and the 2 nd fusion joint MJ2 formed by the heating rod 51 contacting the 2 nd contact region CT2 are stably connected, and the sealing of the accommodation space RS can be ensured more reliably. For the same reason, the 1 st contact region CT1 is preferably connected to (overlaps with) the 3 rd contact region CT 3.

In the example shown in fig. 9, the end edge (EE1) of the contact region on one side (1 st contact region CT1) is located on the outer edge (outer edge OE2) of the contact region on the other side (2 nd contact region CT2), and the end edge (EE2) of the contact region on the other side (2 nd contact region CT2) is located on the outer edge (outer edge OE1) of the contact region on one side (1 st contact region CT 1). By such an example, the two formed welds (the 1 st weld MJ1 and the 2 nd weld MJ2) can be more reliably connected.

However, the positional relationship between the two contact regions is not limited to the example shown in fig. 9, and examples shown in fig. 10 to 13 may be employed. In fig. 9 to 13, one contact region (the 1 st contact region CT1) is indicated by a broken line, and the other contact region (the 2 nd contact region CT2) is indicated by a dotted line.

First, in the example shown in fig. 10, the contact area on one side (the 1 st fusion MJ1) intersects with the contact area on the other side (the 2 nd fusion MJ 2). That is, the contact region on one side (the 1 st fusion MJ1) cuts off the contact region on the other side (the 2 nd fusion MJ 2). Further, the contact region on the other side (the 2 nd fusion joint MJ2) is cut off from the contact region on the one side (the 1 st fusion joint MJ 1). In this example, the two formed welds (the 1 st weld MJ1 and the 2 nd weld MJ2) can be connected more reliably.

Next, in the example shown in fig. 11 and 12, the end edge of one side in the length direction of the contact region of one side is located in the contact region of the other side. In the example shown in fig. 11, the end edge EE1 on one side in the longitudinal direction (the lead-out direction dx) of the 1 st contact region CT1 is located within the 2 nd contact region CT 2. In the example shown in fig. 12, the end edge EE2 of one side in the length direction (width direction dy) of the 2 nd contact region CT2 is located within the 1 st contact region CT 1. In the example shown in fig. 13, the contact area on one side and the contact area on the other side overlap only a part of the width in the width direction perpendicular to the respective length directions. By the example shown in fig. 9 and 11 to 13, the lengths L1, L2 of the respective contact regions from the outer peripheral edge ce of the laminated outer package 40 can be reduced. This can improve the energy density of the laminated secondary battery 1.

The overlap area OA between the one-side contact area (the 1 st contact area CT1) and the other-side contact area (the 2 nd contact area CT2) preferably has a length LOx of 2/5 or more, more preferably 1/2 or more, and still more preferably 2/3, of the width of the other-side contact area in the longitudinal direction of the one-side contact area (the width W2 of the 2 nd contact area CT2), in the longitudinal direction (the lead-out direction dx) of the one-side contact area. Similarly, the overlapping area OA of the contact region on the one side (the 1 st contact region CT1) and the contact region on the other side (the 2 nd contact region CT2) preferably has a length LOy of 2/5 or more, more preferably a length LOx of 1/2 or more, and still more preferably a length LOx of 2/3, of the width of the contact region on the one side in the longitudinal direction of the contact region on the other side (the width W1 of the 1 st contact region CT1), in the longitudinal direction (the width dy) of the contact region on the other side. By setting the overlapping area OA to such a size, the sealing property can be improved around the overlapping portion OP where the two welded portions overlap each other, as described below.

As described above, the 2 nd welded part MJ2 is formed by bringing the pair of heating rods 51 into contact with the outer packaging material 41 in the 2 nd contact region CT2 from both sides, and the 3 rd welded part MJ2 is formed by bringing the pair of heating rods 51 into contact with the outer packaging material 41 in the 3 rd contact region CT3 from both sides. The region where sealant layer 45 of outer package 41 melts is not limited to the region overlapping contact regions CT2 and CT3 with heating rod 51. The sealant layer 45 also melts around the region overlapping the contact regions CT2 and CT 3. Therefore, as shown in fig. 7, the area occupied by the 2 nd welding MJ2 on the laminated outer package 40 includes the area occupied by the 2 nd contact area CT2 on the laminated outer package 40, and the area occupied by the 3 rd welding MJ3 on the laminated outer package 40 includes the area occupied by the 3 rd contact area CT3 on the laminated outer package 40.

Likewise, the 1 st weld MJ1 is formed by contacting a pair of heating rods 51 from both sides with the outer packaging material 41 in the 1 st contact region CT 1. The area occupied by the 1 st weld MJ1 on the laminated outer package 40 includes the area occupied by the 1 st contact area CT1 on the laminated outer package 40. Further, as shown in fig. 7, the 1 st weld MJ1 connects or crosses with the 2 nd weld MJ2 and with the 3 rd weld MJ 3.

In addition, the overlapping area OA of the 1 st contact region CT1 and the 2 nd contact region CT2 and the periphery thereof is melted again at the time of forming the 1 st fusion joint MJ1, the 2 nd fusion joint MJ2 which has been formed. Therefore, the 1 st fusion joint MJ1 and the 2 nd fusion joint MJ2 are integrally and continuously formed, and the liquid-tightness of the accommodating space RS can be ensured. Similarly, the 1 st fusion joint MJ1 and the 3 rd fusion joint MJ3 are integrally and continuously formed, and the liquid-tightness of the accommodating space RS can be ensured.

As described above, the laminated outer package 40 is formed with the welded portions MJ1 to MJ3, and the electrode body 5 and the electrolyte solution are sealed in the housing space RS, thereby obtaining the laminated secondary battery 1. Surprisingly, the laminated secondary battery 1 thus obtained is capable of improving the sealability of the housing space RS and has high reliability. The present inventors confirmed that the reason why the sealing property of the laminated secondary battery 1 is improved is that the thickness of the welded portion obtained by the manufacturing method of the present embodiment is changed. This point will be described below, but the present invention is not limited to the following estimation.

Fig. 14 is a sectional view showing a fusion part obtained by the above-described method, for example, a section along the line XIV-XIV of fig. 9. The 1 st fusion MJ1 includes: an end portion EP located outside the 1 st contact region CT1, a repetition portion OP located inside the repetition region OA in the 1 st contact region CT1, a central portion MP located outside the repetition region OA in the 1 st contact region CT 1. That is, the 1 st fusion MJ1 includes: an end portion EP not pressed by the heating rod 51, a repetition portion OP pressed twice by the heating rod 51, and a central portion MP pressed once by the heating rod 51.

As shown in fig. 14, the thickness of the laminated outer package 40 at the 1 st welding part MJ1 is thicker in both end portions EP in the longitudinal direction of the 1 st welding part MJ1 connecting the outer peripheral edge part ce of the laminated outer package 40 than in the portions (the overlapping portion OP, the central portion MP) located between the both end portions EP. In this way, the thickness of the laminated exterior packaging body 40 at the portion outside (the side opposite to the housing space RS) the overlapping portion OP where the two welded portions overlap is increased, and thus the sealability of the laminated secondary battery 1 can be improved.

In particular, when the total thickness of the sealant layers 45 (the total thickness of the two sealant layers 45 welded together) at the end portion EP of the 1 st welded portion MJ1 of the laminated outer package 40 is at least twice the total thickness of the sealant layers 45 at a portion (the overlapping portion OP, the central portion MP) other than the end portion EP of the 1 st welded portion MJ1 of the laminated outer package 40, the sealability of the laminated secondary battery 1 can be greatly improved.

Further, in the laminated exterior packaging body 40 shown in fig. 14, the thickness at the 1 st welding MJ1 is maximized in both end portions EP. This also contributes to improvement in the sealing property of the laminate-type secondary battery 1.

It should be noted that, as a result of the confirmation by the present inventors, in order to realize the thickness distribution of the welded portion in the longitudinal direction shown in fig. 10, in the manufacturing method, in particular, the overlapping area OA of the one-side contact region and the other-side contact region has, in the longitudinal direction of the one-side contact region, a length LOx of 2/5 or more of the width of the other-side contact region in the longitudinal direction of the one-side contact region, and has, in the longitudinal direction of the other-side contact region, a length Loy of 2/5 or more of the width of the one-side contact region in the longitudinal direction of the other-side contact region is effective. In this case, in the experiment conducted by the present inventors, the sealant layer 45 included in the 1 st part 41A and the 2 nd part 41B of the outer packaging material 41 disposed facing each other before welding had a total thickness of 0.32mm, and after welding, increased to 0.58mm in the end portion EP, decreased to 0.20mm in the repeated portion OP, and decreased to 0.25mm in the central portion MP. In the welded portion of the laminated secondary battery 1 obtained by this experiment, the total thickness of the sealant layers 45 is maximized at the end portion EP, and the total thickness of the sealant layers 45 at the end portion EP is 2.9 times the total thickness of the sealant layers 45 at the positions other than the end portion EP. As a result, the obtained laminated secondary battery 1 has excellent sealing properties.

In one embodiment described above, a method for manufacturing a laminate-type secondary battery 1 includes: and a step of bringing the heating rod 51 into contact with a portion of the laminated exterior packaging body 40 accommodating the electrode body 5, which portion is disposed facing the exterior packaging material 41, to weld the facing exterior packaging material 41, wherein the heating rod 51 is brought into contact with a contact region CT1 located inside the outer peripheral edge ce of the laminated exterior packaging body 40. That is, the contact region CT1 is separated from the outer peripheral edge ce of the laminated exterior packaging body 40. Therefore, the sealant layer 45 located at the outer peripheral edge ce of the laminated exterior package 40 is directly heated by the heating rod 51, and the leakage of the melted sealant material from the laminated exterior package 40 can be avoided. This can effectively prevent the sealant from adhering to the sealing device 50 such as the heating rod 51. Thereby, a large number of laminated secondary batteries 1 can be continuously produced using the same heating rod 51, improving the productivity of the laminated secondary batteries 1.

In the above-described embodiment, the contact area is 0.5mm or more from the outer peripheral edge ce of the laminated exterior body 40. By such an example, the leakage of the melted sealant material from the laminated outer package 40 can be sufficiently effectively prevented.

In the above-described embodiment, the method for manufacturing the laminate-type secondary battery 1 includes: and a step of welding the outer wrapper 41 arranged to face each other by bringing the heating rod 51 into contact with the 2 nd contact region CT2 of the laminated outer wrapper 40. Further, an edge EE2 on one side in the longitudinal direction (width direction dy) of the 2 nd contact region CT2 is located within the contact region CT1, or an edge EE1 on one side in the longitudinal direction (leading direction dx) of the contact region CT1 is located within the 2 nd contact region CT 2. In this example, a laminated secondary battery 1 having excellent sealing properties can be produced. Further, the size of the laminated exterior package 40 can be reduced, and the energy density of the laminated secondary battery 1 can be improved.

In the above embodiment, the overlap area OA between the contact area CT1 and the 2 nd contact area CT2 has a length of 2/5 or more of the width W2 of the 2 nd contact area CT2 in the longitudinal direction (the leading direction dx) of the contact area CT1 along the longitudinal direction of the contact area CT 1. The overlap area OA has a length equal to or greater than 2/5 of the width W1 of the contact area along the longitudinal direction of the 2 nd contact area CT2 in the longitudinal direction (width direction dy) of the 2 nd contact area CT 2. By such an example, the contact region CT1 and the 2 nd contact region CT2 can be made to have a sufficient repetition size, and excellent sealability can be imparted to the laminate-type secondary battery 1.

In the above-described embodiment, the laminated outer package 40 has the linear fusion-bonded portion MJ1 formed by fusion-bonding the outer package materials 41 arranged facing each other. The thickness of the welded part MJ1 of the laminated outer package 40 is thicker in both end parts EP in the longitudinal direction (the lead-out direction dx) of the welded part MJ1 connecting the peripheral edge part ce of the laminated outer package 40 than in the parts OP, MP located between both end parts EP 1. By the laminated outer package 40 having such a welded portion MJ1, the sealability of the accommodating space RS can be improved. This can effectively prevent leakage of the electrolyte solution, such as accidental leakage from the laminated exterior package 40, and can improve the reliability of the laminated secondary battery 1.

In the above-described embodiment, the total thickness of the sealant layers 45 at the both end portions EP of the welding portion MJ1 of the laminated outer package 40 is twice or more the total thickness of the sealant layers 45 at the certain portions OP and MP located between the both end portions EP of the welding portion MJ1 of the laminated outer package 40. By the laminated outer package 40 having such a welded portion MJ1, the sealability of the accommodating space RS can be effectively improved.

In the one embodiment, the thickness at the welding MJ1 of the laminated outer package 40 is maximized in both end portions EP. By the laminated outer package 40 having such a welded portion MJ1, the sealability of the accommodating space RS can be effectively improved.

In the one embodiment, the laminated exterior package 40 includes: and a linear 2 nd welding part MJ2 extending in a linear shape intersecting the 1 st welding part MJ1 and welded to the outer packaging material 41 disposed opposite to each other. The thickness at the 1 st welding MJ1 of the laminated outer package 40 is thicker in the end portion EP located between the repeating portion OP and the outer peripheral edge ce of the laminated outer package 40 than in the repeating portion OP intersecting the 2 nd welding MJ 2. By the laminated outer package 40 having the 1 st weld MJ1 and the 2 nd weld MJ2 as described above, the sealability of the accommodating space RS can be more effectively improved.

In the one embodiment, the thickness at the end portion EP of the laminated outer package 40 is twice or more the thickness at the repeating portion OP of the laminated outer package 40. By the laminated outer package 40 having the 1 st weld MJ1 and the 2 nd weld MJ2 as described above, the sealability of the accommodating space RS can be more effectively improved.

Although an embodiment has been described with specific examples, an embodiment is not limited to these specific examples. The above-described embodiment can be implemented by various other specific examples, and various omissions, substitutions, and changes can be made without departing from the spirit thereof.

For example, in the above-described specific example, the laminated outer package 40 is shown as an example having one piece of the outer package material 41 folded back, but is not limited thereto. The laminated outer package 40 may have: a1 st outer wrapper and a2 nd outer wrapper disposed opposite to each other. In this example, in the case where the laminated exterior package 40 has a rectangular shape in plan view, four welded portions can be formed in the laminated exterior package 40 to seal the housing space RS. Each welded portion may be configured in the same manner as the 1 st welded portion MJ1 in the above example.

Examples

The present invention will be described below with reference to examples, but the present invention is not limited to the following descriptions.

In the same manner as in the above-described manufacturing method, in a state where the electrode body 5 is sandwiched between the laminated exterior packaging body 40 folded back by one sheet of the exterior packaging material 41, first, the 2 nd fusion part MJ2 and the 3 rd fusion part MJ3 are prepared in the laminated exterior packaging body 40, then, after an electrolyte solution is injected into the laminated exterior packaging body 40, the 1 st fusion part MJ1 is prepared in the laminated exterior packaging body 40, and the laminated secondary battery 1 is prepared. Conditions such as the heating temperature of the heating rod 51, the pressure with which the laminated exterior package 40 is pressed by the heating rod 51, and the time with which the laminated exterior package 40 is pressed by the heating rod 51 can be set as normal conditions used in the production of the laminated secondary battery 1, and in the comparative example and the example, the heating rods 51 having different overall lengths are used. In the comparative examples and examples, conditions other than the length of the heating rod were the same.

As shown in fig. 15, the length of the laminated outer package 40 in the lead-out direction dx is set to 509 mm. The 2 nd contact region CT2, which was in contact with the heating rod 51 when the 2 nd fusion part MJ2 was formed, had a width of 8mm in the drawing-out direction dx, 20.5 mm from the 2 nd edge part e in the drawing-out direction dx, and 10.5 mm from the 1 st edge part e in the width direction dy. The 3 rd contact region CT3, which was in contact with the heating rod 51 when the 3 rd welded part MJ3 was formed, had a width of 8mm in the drawing-out direction dx, was 30.5 mm from the 3 rd edge part e in the drawing-out direction dx, and was 10.5 mm from the 1 st edge part e in the width direction dy.

The 1 st weld MJ1 is formed so as to correspond to the 1 st contact region CT1 of the heating rod 51, and the center in the lead-out direction dx corresponds to the center of the laminated outer package 40. Further, the 1 st contact region CT1 has a width of 8mm in the width direction dy and is 10.5 mm from the 1 st edge portion e in the width direction dy. In comparative example 1 and comparative example 2, heating rods 51 having lengths of 514mm and 539mm were used, respectively. Therefore, in comparative examples 1 and 2, the 1 st contact region CT1 has a length of 509mm in the lead-out direction dx, and the heating rod 51 protrudes beyond the 2 nd edge portion e2 and the 3 rd edge portion e3 of the laminated outer package 40. On the other hand, in examples 1 to 3, the heating rods 51 having lengths of 508mm, 503mm and 498mm were used. Therefore, in embodiments 1 to 3, the 1 st contact region CT1 has a length of dx508mm, 503mm, 498mm in the lead-out direction.

In order to facilitate the formation of a plurality of laminated secondary batteries 1 in which the 2 nd welded part MJ2 and the 3 rd welded part MJ3 are formed, the 1 st welded part MJ1 is continuously formed using the same heating rod 51 in each example. In each example, the number of pressing times (number of formation times) at which the sealant material adhered to the heating rod 51 and the formation of the 1 st fusion joint MJ1 became difficult was confirmed.

In examples 1 to 3, 20000 1 st fusion joints MJ1 were formed, but the sealant was not attached to the heating rod 51. On the other hand, in comparative examples 1 and 2, the heating rod 51 needs to be cleaned every 10 times of forming the 1 st welded part MJ 1.

TABLE 1

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Laminated secondary battery and method for manufacturing same

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