JP2020145162A - Power storage element and manufacturing method therefor - Google Patents

Abstract

To provide a power storage element in which sheath materials in a region apart from a junction region are hard to be bonded.SOLUTION: The power storage element includes: an outer sheath 7 having a first sheath material and a second sheath material; and an electrode body 5 housed in a housing space 7a formed between the first and second sheath materials, and including a plurality of first electrodes and a plurality of second electrodes in lamination. The first sheath material includes: a peripheral part; and a swelled part surrounded by the peripheral part and swelled out from the peripheral part in a direction apart from the second sheath material. The first and second sheath materials are bonded in a junction region which is partially overlapped with the peripheral part and surrounds the swelled part in a circumferential shape. In a position between the junction region and the swelled part, at least one of the first and second sheath materials includes a protrusion part 47 which protrudes in a direction apart from the other of the first and second sheath materials and extends linearly. The projection part is provided circumferentially along the junction region.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power storage element and a method for manufacturing the power storage element.

As a power storage element, for example, as proposed in Patent Document 1, a laminated battery or a wound battery in which positive electrodes and negative electrodes are alternately laminated is widely used. An example of such a laminated battery is a lithium ion secondary battery. One of the features of lithium-ion secondary batteries is that they have a larger capacity than other types of stacked batteries. Lithium-ion secondary batteries having such characteristics are expected to be further spread in various applications such as in-vehicle applications and stationary housing applications.

In a laminated battery represented by a lithium ion secondary battery, in order to extract power from an electrode body having a positive electrode and a negative electrode, the positive electrode and the negative electrode are separated from each other in a region of the positive electrode and the negative electrode where an electrode active material layer is not provided. A tab is attached to the electrode current collector of each of the collected electrodes. The electrode body is housed in the exterior body in a state where the tabs attached to the respective electrodes extend outward.

Such an exterior body is formed by joining two exterior materials. The two exterior materials are joined by heating and pressurizing a joining region that overlaps a part of the peripheral edge thereof.

JP-A-2009-110816

By the way, when the joint region is heated and pressurized, a region distant from the intended joint region may also be joined. That is, the exterior material may be joined to an unintended area. Areas that are not intended to be joined, apart from the joining area, are joined weaker than the joining area. Therefore, for example, when a force is applied by a gas or the like generated inside the exterior body, the joint in the region away from the joint region is easily peeled off. As a result, problems such as leakage of the electrolytic solution sealed inside the exterior body to the outside of the power storage element may occur. Such a defect may adversely affect the safety in handling the power storage element.

The present invention has been made in consideration of such a point, and an object of the present invention is to make it difficult for the exterior material to be joined in a region away from the joining region.

The power storage element of the present invention
An exterior body having a first exterior material and a second exterior material,
An electrode body having a plurality of first electrodes and a plurality of second electrodes accommodated and laminated in an accommodation space formed between the first exterior material and the second exterior material is provided.
The first exterior material has a peripheral edge portion and a bulging portion that is surrounded by the peripheral edge portion and bulges from the peripheral edge portion in a direction away from the second exterior material.
The first exterior material and the second exterior material are joined in a joint region that overlaps a part of the peripheral edge portion and surrounds the bulging portion in a circumferential shape.
At least one of the first exterior material and the second exterior material is located at a position between the joint region and the bulging portion in a direction away from the other of the first exterior material and the second exterior material. It has a protruding part that extends linearly,
The protruding portion is provided in a circumferential shape along the joint region.

In the power storage element of the present invention, the first exterior material may have a metal layer and a resin layer laminated on the metal layer and located closer to the second exterior material than the metal layer.

In the power storage element of the present invention, the resin layer may have thermoplasticity.

In the power storage element of the present invention, the distance between the protruding portion and the bonding region may be 1.0 mm or less.

In the power storage element of the present invention, the distance between the protruding portion and the bonding region may be 0.5 mm or more.

In the power storage element of the present invention, the width of the protruding portion may be 0.8 mm or more.

In the power storage element of the present invention, the distance between the bulging portion and the joining region may be 2.0 mm or more.

In the power storage element of the present invention, the electrode body may have a separator arranged between the first electrode and the second electrode.

In the power storage element of the present invention
The second exterior material includes a second peripheral edge portion and a second bulging portion that is surrounded by the second peripheral edge portion and bulges from the second peripheral edge portion in a direction away from the first exterior material. And
The joint region is a region that overlaps a part of the second peripheral edge portion, and may surround the second bulging portion in a circumferential shape.

In the power storage element of the present invention, the protruding portion has a first protruding portion protruding from the first exterior material in a direction away from the second exterior material and a second exterior portion in a direction away from the first exterior material. A second protrusion protruding from the material may be included.

The method for manufacturing a power storage element of the present invention is any of the above-mentioned methods for manufacturing a power storage element.
A step of forming a protrusion on at least one of the first exterior material and the second exterior material, and
A step of arranging an electrode body having a plurality of first electrodes and a plurality of second electrodes in an accommodation space formed between the first exterior material and the second exterior material.
A step of joining the first exterior material and the second exterior material in a direction in which the protruding portion projects in a direction away from the other of the first exterior material and the second exterior material is provided.
The protruding portion is formed in a circumferential shape along a joint region for joining the first exterior material and the second exterior material.

In the method for manufacturing a power storage element of the present invention, the protruding portion may be formed by embossing.

In the method for manufacturing a power storage element of the present invention,
The bulge is formed by embossing and
The protruding portion and the bulging portion may be formed at the same time.

In the step of joining the first exterior material and the second exterior material in the method for manufacturing a power storage element of the present invention, the bonding region may be heated at 200 ° C. or higher.

In the method for manufacturing a power storage element of the present invention, in the step of joining the first exterior material and the second exterior material, a pressure of 1.5 MPa or more may be applied to the bonding region.

In the step of joining the first exterior material and the second exterior material in the method for manufacturing a power storage element of the present invention, the bonding region may be heated and / or pressurized for 5 seconds or longer.

According to the present invention, it is possible to make it difficult for the exterior material to be joined in a region away from the joining region.

FIG. 1 is a diagram for explaining an embodiment of the present invention, and is a perspective view showing a power storage element. FIG. 2 is a top view of the power storage element of FIG. FIG. 3 is a plan view showing an electrode body housed inside the exterior body of the power storage element of FIG. FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 1 of FIG. FIG. 5 is a cross-sectional view of the exterior body of the power storage element along the line VV of FIG. FIG. 6 is an enlarged cross-sectional view showing the protruding portion in FIG. FIG. 7 is a cross-sectional view showing another example of the protrusion of FIG. FIG. 8 is a cross-sectional view showing still another example of the protrusion of FIG. FIG. 9 is a diagram showing a modified example of the cross-sectional view of the exterior body shown in FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, the scale, aspect ratio, etc. are appropriately changed from those of the actual product and exaggerated for the sake of ease of understanding.

It should be noted that the terms such as "parallel", "orthogonal", and "same", and the values of length and angle, etc., which specify the shape and geometric conditions and their degrees, which are used in the present specification, are strictly defined. Without being bound by the meaning, we will interpret it including the range where similar functions can be expected.

1 to 8 are diagrams for explaining an embodiment of a power storage element according to the present invention. FIG. 1 is a perspective view showing a specific example of the power storage element, and FIG. 2 is a top view of the power storage element of FIG. As shown in FIGS. 1 and 2, the power storage element 1 is connected to the exterior body 7, the electrode body 5 housed in the accommodation space 7a formed by the exterior body 7, and the exterior body 7 and is connected to the exterior body 7. It has a tab 6 extending from the inside to the outside. Further, FIG. 3 is a plan view showing the electrode body 5 included in the power storage element 1, and FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. As shown in FIGS. 3 and 4, the electrode body 5 has a plurality of first electrodes 10 and second electrodes 20 laminated in the first direction d1. In the example shown in FIG. 1, the power storage element 1 has a flat shape in which the first direction d1 in the thickness direction is thin as a whole, and is in the longitudinal direction and the second direction d2 in the lateral direction. It extends in the third direction d3. The first direction d1, the second direction d2, and the third direction d3 are non-parallel to each other, and in the illustrated example, the first direction d1, the second direction d2, and the third direction d3 are orthogonal to each other.

Hereinafter, an example in which the power storage element 1 is a laminated battery, specifically, a lithium ion secondary battery will be described. In this example, the first electrode 10 constitutes the positive electrode 10X, and the second electrode 20 constitutes the negative electrode 20Y. However, as can be understood from the description of the action and effect described below, one embodiment described here is not limited to the lithium ion secondary battery, and the first electrode 10 and the second electrode 20 are used. It can be widely applied to the power storage element 1 formed by alternately stacking in the first direction d1. Further, the power storage element 1 is not limited to the laminated battery, and may be, for example, a wound battery. Even when the power storage element 1 is a wound battery, the first electrode 10 and the second electrode 20 are laminated in the first direction d1.

Hereinafter, each component of the power storage element 1 will be described.

First, the electrode body 5 will be described. As shown in FIGS. 3 and 4, the electrode body 5 includes a positive electrode 10X (first electrode 10), a negative electrode 20Y (second electrode 20), and a separator 30 arranged between the positive electrode 10X and the negative electrode 20Y. ,have. As shown in FIG. 4, the positive electrode 10X and the negative electrode 20Y are alternately laminated along the first direction d1. The electrode body 5 includes, for example, 20 or more plate-shaped positive electrodes 10X and 20Y in total. The electrode body 5 has a flat shape as a whole, has a thin thickness in the first direction d1, and extends in the second direction d2 and the third direction d3, which are non-parallel to the first direction d1. The thickness of the electrode body 5, that is, the length along the first direction d1, is, for example, 4 mm or more and 20 mm or less.

In the non-limiting example shown in FIG. 3, the positive electrode 10X and the negative electrode 20Y are plate-shaped electrodes having a substantially rectangular outer contour. The second direction d2, which is non-parallel to the first direction d1, is the longitudinal direction of the positive electrode 10X and the negative electrode 20Y, and the third direction d3, which is non-parallel to both the first direction d1 and the second direction d2, is the positive direction 10X and the negative electrode. It is the short side direction (width direction) of 20Y. As shown in FIG. 3, the positive electrode 10X and the negative electrode 20Y are arranged so as to be offset in the second direction d2. More specifically, the plurality of positive electrodes 10X are arranged closer to one side in the second direction d2, and the plurality of negative electrodes 20Y are arranged closer to the other side in the second direction d2. As shown in FIG. 3, the positive electrode 10X and the negative electrode 20Y overlap with the first direction d1 at the center in the second direction d2.

As shown in FIG. 3, the length of the negative electrode 20Y (second electrode 20) along the third direction d3 (width direction) is along the third direction d3 of the positive electrode 10X (first electrode 10). It is longer than the length. In the illustrated example, the negative electrode 20Y extends from the positive electrode 10X to one side and the other side of the third direction d3. The thickness of the positive electrode 10X and the negative electrode 20Y, that is, the length in the first direction d1 is, for example, 80 μm or more and 200 μm or less, and the length in the longitudinal direction, that is, along the second direction d2 is, for example, 200 mm or more and 950 mm or less. The length (width) in the lateral direction, that is, along the third direction d3 is, for example, 70 mm or more and 350 mm or less.

As shown in FIGS. 3 and 4, the positive electrode 10X (first electrode 10) includes the positive electrode current collector 11X (first electrode current collector 11) and the positive electrode provided on the positive electrode current collector 11X. It has an active material layer 12X (first electrode active material layer 12). In the lithium ion secondary battery, the positive electrode 10X emits lithium ions when discharged and occludes lithium ions when charged.

As shown in FIG. 4, the positive electrode current collector 11X has a first surface 11a and a second surface 11b facing each other as main surfaces. The positive electrode active material layer 12X is formed on both surfaces of the first surface 11a and the second surface 11b of the positive electrode current collector 11X. The plurality of positive electrodes 10X included in the electrode body 5 have a pair of positive electrode active material layers 12X provided on both sides of the positive electrode current collector 11X, and may be configured to be the same as 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 power storage element 1 (lithium ion secondary battery). As an example, the positive electrode current collector 11X can be formed of an 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 is produced by coating a positive electrode slurry formed by dispersing a positive electrode active material, a conductive auxiliary agent, and a binder in a solvent on a material forming the positive electrode current collector 11X and solidifying the positive electrode active material layer 12X. Can be done. As the positive electrode active material, for example, a lithium metallic acid compound represented by the general formula LiM _x O _y (where M is a metal and x and y are composition ratios of metal M and oxygen O) is used. Specific examples of the lithium metallic acid compound include lithium cobalt oxide, lithium nickel oxide, lithium manganate and the like. Alternatively, as the positive electrode active material, a lithium metal phosphate compound represented by the general formula LiMPO ₄ (where M is a metal) may be used. Specific examples of the metallic lithium phosphate compound include lithium iron phosphate, lithium manganese phosphate, lithium cobalt phosphate, and the like. As the conductive auxiliary agent, acetylene black or the like can be used. As the binder, polyvinylidene fluoride or the like can be used.

As shown in FIG. 3, 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 second direction d2. The first end region a1 is located outside the first electrode region b1 in the second direction d2 (left side in FIG. 3). As shown in FIG. 3, the plurality of positive electrode current collectors 11X are joined by resistance welding, ultrasonic welding, tape bonding, fusion, etc. in the first end region a1, and are electrically connected. .. In the illustrated example, one tab 6 is electrically connected to the positive electrode current collector 11X in the first end region a1. The tab 6 extends from the electrode body 5 in the second direction d2. On the other hand, as shown in FIG. 3, the first electrode region b1 is located in the region of the negative electrode 20Y facing the negative electrode active material layer 22Y described later. The width of the positive electrode 10X along the third direction d3 is narrower than the width of the negative electrode 20Y along the third direction d3. By arranging the first electrode region b1 in this way, it is possible to prevent the precipitation of lithium from the negative electrode active material layer 22Y.

Next, the negative electrode 20Y (second electrode 20) will be described. The negative electrode 20Y (second electrode 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 22) provided on the negative electrode current collector 21Y. And have. In the lithium ion secondary battery, the negative electrode 20Y occludes lithium ions during discharging and releases lithium ions during charging.

As shown in FIG. 3, 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 both surfaces of the first surface 21a and the second surface 21b of the negative electrode current collector 21Y. The plurality of negative electrode bodies 20Y included in the electrode body 5 have a pair of negative electrode active material layers 22Y provided on both sides of the negative electrode current collector 21Y, and may be configured to be identical 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 power storage element 1 (lithium ion secondary battery). As an example, the negative electrode current collector 21Y is formed of, for example, a copper foil. 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 forms a negative electrode current collector 21Y, for example, a slurry for a negative electrode formed by dispersing a negative electrode active material made of carbon powder, graphite powder, or the like and a binder such as polyvinylidene fluoride in a solvent. It can be produced by coating on a material and solidifying it.

As shown in FIG. 3, the negative electrode current collector 21Y (second electrode current collector 21) has a second connection region a2 and a second electrode region b2. The negative electrode active material layer 22Y (second electrode active material layer 22) is laminated on the negative electrode current collector 21Y only in the second electrode region b2. The second connection region a2 and the second electrode region b2 are arranged in the second direction d2. The second electrode region b2 is located on one side (left side in FIG. 3) in the second direction d2 with respect to the second connection region a2. As shown in FIG. 3, the plurality of negative electrode current collectors 21Y are bonded by resistance welding, ultrasonic welding, bonding with tape, fusion, etc. in the second connection region a2, and are electrically connected. In the illustrated example, a tab 6 other than the tab connected to the positive electrode current collector 11X is electrically connected to the negative electrode current collector 21Y in the second connection region a2. The tab 6 extends from the electrode body 5 to the other side in the second direction d2.

As described above, the first electrode region b1 of the positive electrode 10X is located inside the region of the negative electrode 20Y facing the second electrode region b2 (see FIG. 3). That is, the second electrode region b2 extends to a region including a region of the positive electrode 10X facing the positive electrode active material layer 12X. The width of the negative electrode 20Y along the third direction d3 is wider than the width of the positive electrode 10X along the third direction d3. In particular, the one-sided end portion 20a of the negative electrode 20Y in the third direction d3 is located on one side in the third direction d3 of the positive electrode 10X with respect to the one-sided end portion 10a in the third direction d3, and the negative electrode 20Y is the third. The other side end 20b in the three directions d3 is located on the other side in the third direction d3 with respect to the other side end 10b in the third direction d3 of the positive electrode 10X.

Next, the separator 30 will be described. As shown in FIG. 4, the separator 30 is located between the positive electrode 10X (first electrode 10) and the negative electrode 20Y (second electrode 20), and is separated from each other so that the positive electrode 10X and the negative electrode 20Y do not come into contact with each other. There is. The separator 30 has an insulating property and prevents a short circuit due to contact between the positive electrode 10X and the negative electrode 20Y. The separator 30 preferably has a large ion permeability (air permeability), a predetermined mechanical strength, and durability against an electrolytic solution, a positive electrode active material, a negative electrode active material, and the like. As such a separator 30, for example, a porous body or a non-woven fabric formed of an insulating material can be used. More specifically, as the separator 30, a porous film made of a thermoplastic resin having a melting point of about 80 to 140 ° C. can be used. As the thermoplastic resin, a polyolefin-based polymer such as polypropylene or polyethylene, or polyethylene terephthalate can be adopted. An electrolytic solution is sealed together with the electrode body 5 in the accommodation space 7a of the exterior body 7. By impregnating the separator 30 made of a porous body or a non-woven fabric with the electrolytic solution, the electrolytic solution is maintained in contact with the electrode active material layers 12 and 22 of the electrodes 10 and 20.

The separator 30 is located, for example, between any two electrodes 10 and 20 adjacent to each other in the first direction d1. Further, the separator 30 extends so as to cover the entire region of the positive electrode active material layer 12X of the positive electrode 10X in a plan view. Similarly, the separator 30 extends so as to cover the entire region of the negative electrode active material layer 22Y of the negative electrode 20Y in a plan view.

Next, tab 6 will be described. The tab 6 functions as a terminal in the power storage element 1. As shown in FIGS. 3 and 4, one tab 6 (one side of the second direction d2) is electrically connected to the positive electrode 10X (first electrode 10) of the electrode body 5. Similarly, the tab 6 on the other side (the other side of the second direction d2) is electrically connected to the negative electrode 20Y (second electrode 20) of the electrode body 5. As shown in FIGS. 1 and 4, the pair of tabs 6 extend from the accommodation space 7a inside the exterior body 7 to the outside of the exterior body 7. The length extending to the outside of the exterior body 7 of the tab 6 is, for example, 10 mm or more and 25 mm or less. As shown in FIG. 4, the tab 6 is between the first exterior material 40 and the second exterior material 50 of the exterior body 7, which will be described later, and more specifically, the first resin layer 42 of the first exterior material 40. It passes between the second exterior material 50 and the second resin layer 52. Further, the outer body 7 and the tab 6 are sealed in the region where the tab 6 extends.

The tab 6 has a tab body portion 6a having conductivity and a seal portion 6b provided on the tab body portion 6a. A portion of one tab 6 located on one side of the tab body 6a in the second direction d2 extends to the outside of the exterior body 7 and is located on the other side of the tab body 6a in the second direction d2. Is connected to the positive electrode 10X (first electrode 10). A portion of the tab body 6a of the other tab 6 located on the other side in the second direction d2 extends to the outside of the exterior body 7, and a portion of the tab body 6a located on one side in the second direction d2. Is connected to the negative electrode 20Y (second electrode 20). The seal portion 6b surrounds the tab body portion 6a at the central portion of the tab body portion 6a in the second direction d2. The seal portion 6b is welded to the exterior body 7 and seals between the tab body portion 6a and the exterior body 7. The seal portion 6b effectively prevents contact between the tab body portion 6a and the exterior body 7, particularly contact between the tab body 6a and the exterior body 7 with the metal layer 41 of the first exterior material 40.

The tab body 6a may be formed of aluminum, copper, nickel, nickel-plated copper or the like. The thickness of the tab body 6a is, for example, 0.1 mm or more and 1 mm or less. Examples of the material of the sealing portion 6b include polypropylene, modified polypropylene, low-density polypropylene, ionomer, ethylene / vinyl acetate and the like. The thickness of the seal portion 6b is, for example, 0.05 mm or more and 0.4 mm or less.

Next, the exterior body 7 will be described with reference to FIGS. 2 and 5. FIG. 5 is a cross-sectional view of the power storage element 1 along the VV line of FIG. 1 with the electrode body 5 removed for simplification of the illustration. That is, FIG. 5 shows a cross-sectional view of the exterior body 7.

The exterior body 7 is a packaging body for sealing the electrode body 5. The exterior body 7 forms an accommodation space 7a for accommodating the electrode body 5. The exterior body 7 seals the electrode body 5 and the electrolytic solution in the accommodation space 7a inside the body 5.

The accommodation space 7a has a size larger than the size of the electrode body 5 so that the electrode body 5 can be accommodated. On the other hand, in order to increase the volumetric energy density of the power storage element 1, the accommodation space 7a is preferably small. Here, the volumetric energy density means the amount of electric power that can be supplied by the power storage element per volume occupied by the power storage element. Therefore, it is preferable that the size of the accommodation space 7a is the same as the size of the electrode body 5. In other words, the exterior body 7 is preferably in contact with the electrode body 5 contained therein. The accommodation space 7a is formed so as to have a shape that matches the shape of the electrode body 5 to be accommodated. In the illustrated example, the accommodation space 7a has a substantially rectangular parallelepiped shape. The accommodation space 7a has, for example, a length of 5 mm or more and 25 mm or less along the first direction d1, a length of 200 mm or more and 1000 mm or less along the second direction d2, and a length along the third direction d3. Is 70 mm or more and 400 mm or less.

Further, the exterior body 7 has a first exterior material 40 and a second exterior material 50. The first exterior material 40 and the second exterior material 50 are joined in the joining region A1. The first exterior material 40 and the second exterior material 50 are joined by, for example, welding. The accommodation space 7a is formed by joining the first exterior material 40 and the second exterior material 50. The thickness of the first exterior material 40 and the second exterior material 50 is, for example, 0.1 mm or more and 0.3 mm or less.

As shown in FIGS. 2 and 5, the first exterior material 40 has a first peripheral edge portion 45 and a first bulging portion 46 surrounded by the first peripheral edge portion 45. The first bulging portion 46 bulges from the first peripheral edge portion 45 in a direction away from the second exterior material 50. The accommodation space 7a is formed by the first bulging portion 46. The joint region A1 is a region that overlaps a part of the first peripheral edge portion 45 and surrounds the first bulging portion 46 in a circumferential shape. Therefore, by joining the joining region A1, the accommodation space 7a formed by the first bulging portion 46 can be made into a closed space. Further, the distance D1 between the first bulging portion 46 and the joint region A1 is 2.0 mm or more.

As shown in FIG. 5, the first exterior material 40 includes a first metal layer 41 and a first resin layer 42 laminated on the first metal layer 41. Similarly, the second exterior material 50 includes a second metal layer 51 and a second resin layer 52 laminated on the second metal layer 51. The first exterior material 40 and the second exterior material 50 are arranged so that the first resin layer 42 of the first exterior material 40 and the second resin layer 52 of the second exterior material 50 face each other. Further, in the illustrated example, the first exterior material 40 is provided on the surface of the first metal layer 41, that is, on the surface opposite to the surface on which the first resin layer 42 of the first metal layer 41 is laminated. A first insulating layer 43 having an insulating property is further included. Further, in the illustrated example, the second exterior material 50 is provided on the surface of the second metal layer 51, that is, on the surface opposite to the surface on which the second resin layer 52 of the second metal layer 51 is laminated. A second insulating layer 53 having an insulating property is further included. As shown in FIG. 4, in the second direction d2, the tab 6 passes between the first resin layer 42 of the first exterior material 40 and the second resin layer 52 of the second exterior material 50.

The first metal layer 41 and the second metal layer 51 preferably have high gas barrier properties and moldability, and for example, aluminum foil, stainless steel foil, or the like can be used. The first resin layer 42 and the second resin layer 52 prevent the electrode body 5 housed in the storage space 7a from being electrically connected to the first metal layer 41 and the second metal layer 51. As the first resin layer 42 and the second resin layer 52, for example, polypropylene or the like can be used. The first insulating layer 43 and the second insulating layer 53 prevent the external conductor from being electrically connected to the first metal layer 41 and the second metal layer 51. The first insulating layer 43 and the second insulating layer 53 are, for example, thin nylon layers.

Further, in the illustrated example, the first exterior material 40 further has a first protrusion 47 that projects in a direction away from the second exterior material 50 and extends linearly from the first peripheral edge 45 in a plan view. ing. That is, the first protruding portion 47 protrudes in the first direction d1. The first protruding portion 47 is located between the joint region A1 and the first protruding portion 46. As is well shown in FIGS. 1 and 2, the linearly extending first protrusion 47 is provided in a circumferential shape along the joint region A1. In other words, the first protruding portion 47 surrounds the first protruding portion 46. In the illustrated example, the first protrusion 47 extends along the four sides forming the junction region A1 and includes four straight portions and four curved portions.

The first protruding portion 47 will be further described with reference to FIGS. 2 and 6 to 8. The first projecting portion 47 suppresses heat transfer to a region away from the joining region A1 when the first exterior material 40 and the second exterior material 50 are joined. In order to effectively suppress heat transfer to a region away from the joint region A1, it is preferable that the first protrusion 47 is arranged at an appropriate distance from the joint region A1. Specifically, the distance D2 between the first protruding portion 47 and the joint region A1 is preferably 0.5 mm or more and 1.0 mm or less. Further, the width W of the first protruding portion 47 extending linearly, that is, the length in the direction orthogonal to the extending direction of the first protruding portion 47 is preferably 0.8 mm or more. Further, the height H of the first protruding portion 47, that is, the length along the first direction d1 is, for example, 0.5 mm or more and 4.5 mm or less.

As shown in FIG. 6, the shape of the first protruding portion 47 in the cross section of the exterior body 7 is rectangular. The first protruding portion 47 having a rectangular cross section can effectively suppress heat transfer to a region away from the joint region A1. However, the shape of the first protrusion 47 in the cross section of the exterior body 7 may be triangular as shown in FIG. The first protrusion 47 having a triangular cross section can be easily formed. Alternatively, the shape of the first protruding portion 47 in the cross section of the exterior body 7 may be a part of an elliptical shape as shown in FIG. A part of the first protruding portion 47 having an elliptical cross section can extremely effectively suppress heat transfer to a region away from the joint region A1. Furthermore, the shape of the first protruding portion 47 in the cross section of the exterior body 7 is not limited to the examples shown in FIGS. 6 to 8, and may be any shape. For example, if the shape of the first protruding portion 47 in the cross section of the exterior body 7 is a part of a circle, the first protruding portion 47 can be easily molded and heat is transferred to a region away from the joint region A1. Can be effectively suppressed.

Next, an example of the manufacturing method of the power storage element 1 of the present embodiment will be described.

First, an electrode body 5 is prepared in which a plurality of first electrodes 10 and 20 are alternately laminated, and a separator 30 is arranged between the first electrode 10 and the second electrode 20. On one side of the electrode body 5 in the second direction d2, the tab 6 is electrically connected to the first electrode 10, and on the other side in the second direction d2, another tab 6 is electrically connected to the second electrode 20. To do.

In addition, the first exterior material 40 and the second exterior material 50 are produced. The first exterior material 40 and the second exterior material 50 to be produced are produced by laminating, for example, metal layers 41, 51 made of aluminum foil with resin layers 42, 52 made of, for example, polyethylene, polypropylene, or polyethylene terephthalate. .. The first exterior material 40 and the second exterior material 50 are formed in a flat plate shape.

Next, the first bulging portion 46 and the first protruding portion 47 are formed on the first exterior material 40. The first bulging portion 46 and the first protruding portion 47 are formed by, for example, embossing the first exterior material 40. The first protruding portion 47 is formed in a circumferential shape along the joint region A1 that joins the first exterior material 40 and the second exterior material 50. The first projecting portion 47 is formed so as to project away from the second exterior material 50, that is, in a direction away from the first resin layer 42. The first bulging portion 46 and the first protruding portion 47 may be formed separately, but are preferably formed at the same time in order to reduce the manufacturing cost of the first exterior material 40.

After that, the electrode body 5 is arranged between the first exterior material 40 and the second exterior material 50, and the first exterior material 40 and the second exterior material 50 are joined in the joining region A1 overlapping a part of the first peripheral edge portion 45. To do. The first exterior material 40 and the second exterior material 50 are arranged so that the sides of the first resin layer 42 and the second resin layer 52 face each other. In other words, the first exterior material 40 and the second exterior material 50 are joined in a direction in which the first projecting portion 47 projects in a direction away from the second exterior material 50.

The first exterior material 40 and the second exterior material 50 are joined by welding, for example, by heating and pressurizing the joining region A1. This heating / pressurizing is performed by heating the bonding region A1 intended to be bonded by a heat bar or the like to 200 ° C. or higher, and maintaining a state in which a pressure of 1.5 MPa or higher is applied for 5 seconds or longer. Will be done. By joining the first exterior material 40 and the second exterior material 50, the electrode body 5 is accommodated in the accommodation space 7a formed by the first bulging portion 46.

By the above steps, the power storage element 1 as shown in FIG. 1 is manufactured.

By the way, as described above, in the conventional power storage element, when the bonding region is heated and pressurized, a region that is separated from the intended bonding region and is not intended to be bonded may also be heated and bonded. is there. One of the causes of joining exterior materials in such a region that is not intended to be joined is that when the joining region is heated and pressurized, the region away from the joining region is also heated by heat conduction and heat radiation. Is inferred. The region away from the joining region is heated only weaker than the joining region, so that the region is joined weaker than the joining region. Therefore, it is considered that the joint in the region away from the joint region is easily peeled off. In particular, it was confirmed that the unintentionally joined region, which is separated from the joining region intended to be joined, is joined only very weakly and is easily peeled off by an unexpected external force or the like. If the joint is peeled off, a problem such as leakage of the electrolytic solution sealed inside the exterior body to the outside of the power storage element may occur.

On the other hand, in the present embodiment, the first exterior material 40 projects linearly at a position between the joint region A1 and the first bulging portion 46 in a direction away from the second exterior material 50. It has one protruding portion 47. The first protruding portion 47 is provided in a circumferential shape along the joint region A1. Since the first protrusion 47 is provided between the joint region A1 and the first bulge 46, the region where the heat applied to the joint region A1 exceeds the first protrusion 47 and is separated from the joint region A1. It is suppressed from being transmitted to. In particular, since the linear first protrusion 47 is provided in a circumferential shape along the joint region A1, the heat applied to the joint region A1 over the entire area of the joint region A1 causes the first protrusion 47. It is suppressed that it is transmitted to a region far from the junction region A1. Therefore, it becomes difficult for heat to be transferred to a region away from the bonding region A1 intended to be bonded. In the region where heat is not transferred, the first exterior material 40 and the second exterior material 50 are not joined. In this way, when the joining region A1 is heated for joining by the first protruding portion 47, the first exterior material 40 and the second exterior material 50 are joined in a region away from the intended joining region A1. It can be made difficult.

Further, the first exterior material 40 includes a first metal layer 41 and a first resin layer 42 laminated on the first metal layer 41 and located closer to the second exterior material 50 than the first metal layer 41. are doing. When the first exterior material 40 has the first metal layer 41 and the first resin layer 42, if there is a region that is weaker than the bonding region A1 and is separated from the bonded region A1, inside the exterior body 7. When the joint between the first exterior material 40 and the second exterior material 50 is peeled off by applying a force due to the generated gas or the like, the first metal layer 41 and the first resin layer 42 of the first exterior material 40 are peeled off. It may end up. That is, the first metal layer 41 may be exposed inside the exterior body 7. When the exposed first metal layer 41 comes into contact with the electrolytic solution sealed in the exterior body 7, the first metal layer 41 is corroded, and as a result, the electrolytic solution sealed inside the exterior body 7 is released. Problems such as leakage and deformation of the exterior body 7 may occur. Such a defect may adversely affect the safety in handling the power storage element 1. As in the present embodiment, when the joint region A1 is heated by the first protrusion 47, the first exterior material 40 and the second exterior material 50 are joined in a region away from the intended joint region A1. By making it difficult, it is possible to effectively suppress the occurrence of such a problem. As described above, when the first exterior material 40 has the first metal layer 41 and the first resin layer 42, the first exterior material 40 and the second exterior material 50 are located in a region away from the intended joining region A1. The effect of making it difficult to join can be particularly effectively achieved.

Further, the first resin layer 42 has thermoplasticity. By heating the first resin layer 42 having thermoplasticity, the first resin layer 42 is melted, and the first exterior material 40 and the second exterior material 50 are joined via the first resin layer 42. In the present embodiment, by providing the first protrusion 47, it is possible to prevent the heat applied to the joint region A1 from being transferred to the region beyond the first protrusion 47 and away from the joint region A1. .. In the region where heat is not transferred, the first resin layer 42 is not heated, so that the first resin layer 42 does not melt, and therefore the first exterior material 40 and the second exterior material 50 are not joined. As described above, when the first resin layer 42 has thermoplasticity, when the joint region A1 is heated by the first protruding portion 47, the first exterior material 40 and the first exterior material 40 and the region away from the intended joint region A1 The effect of making the second exterior material 50 particularly difficult to join can be effectively exerted.

Further, the first protruding portion 47 and the joint region A1 are sufficiently close to each other. Specifically, the distance between the first protruding portion 47 and the joint region A1 is 1.0 mm or less. Since the first protruding portion 47 and the joining region A1 are adjacent to the joining region A1, they are likely to be joined unintentionally. Since the region between the first protrusion 47 and the joint region A1 that can be joined unintentionally is sufficiently narrowed, the first exterior material is formed between the first protrusion 47 and the joint region. It is possible to effectively prevent the 40 and the second exterior material 50 from being unintentionally joined together.

Further, the first protruding portion 47 and the joint region A1 are sufficiently separated from each other. Specifically, the distance between the first protruding portion 47 and the joint region A1 is 0.5 mm or more. The heat applied to the joint region A1 is transferred to the first protruding portion 47, and further, when the heat transferred to the first protruding portion 47 is excessive, it can be transferred beyond the first protruding portion 47. When the first protrusion 47 and the joint region A1 are sufficiently separated from each other, excessive heat is not transferred to the first protrusion 47, and therefore heat is suppressed from being transferred beyond the first protrusion 47. be able to. That is, it is possible to make it difficult for the first exterior material 40 and the second exterior material 50 to be joined in a region away from the joining region A1.

Further, the first protruding portion 47 has a sufficiently large width. Specifically, the width of the first protruding portion 47 is 0.8 mm or more. Therefore, the heat transferred from the joint region A1 to the first protruding portion 47 is difficult to be transferred beyond the first protruding portion 47. That is, it is possible to make it difficult for the first exterior material 40 and the second exterior material 50 to be joined in a region away from the joining region A1.

Further, the first bulging portion 46 and the joining region A1 are sufficiently separated from each other. Specifically, the distance between the first bulging portion 46 and the joint region A1 is 2.0 mm or more. Therefore, the heat applied to the joint region A1 is difficult to be transferred into the accommodation space 7a formed by the first bulging portion 46. Therefore, it is possible to effectively suppress defects of the electrode body 5 due to heat such as heat being transferred to the electrode body 5 housed in the accommodation space 7a and the separator 30 contracting.

Further, in the bonding between the first exterior material 40 and the second exterior material 50, the bonding region A1 of the first exterior material 40 and the second exterior material 50 was pressurized to 1.5 MPa or more while heating to 200 ° C. or more. It is performed by maintaining the state for 5 seconds or more. Since the first exterior material 40 and the second exterior material 50 are joined under such conditions, the first exterior material 40 and the second exterior material 50 can be reliably joined. Further, since the first protruding portion 47 is provided, even if the joint region A1 is placed under high temperature and high pressure for such a long time, heat is not easily transferred to a region away from the joint region A1. That is, by providing the first protruding portion 47, it is possible to make it difficult for the first exterior material 40 and the second exterior material 50 to be joined in a region away from the joining region A1.

As described above, the power storage element 1 of the present embodiment is formed between the exterior body 7 having the first exterior material 40 and the second exterior material 50 and the first exterior material 40 and the second exterior material 50. The first exterior material 40 includes a first peripheral edge portion 45 and a first peripheral edge portion 45, which includes an electrode body 5 having a plurality of first electrodes 10 and a plurality of second electrodes 20 accommodated and laminated in the accommodation space 7a. It has a first bulging portion 46 that is surrounded by the portion 45 and bulges from the first peripheral edge portion 45 in a direction away from the second exterior material 50, and the first exterior material 40 is the first peripheral edge portion 45. In a joint region A1 that surrounds the first bulging portion 46 in a partial region, the second exterior material 50 is joined, and the first exterior material 40 is formed by joining the joining region A1 and the first bulging portion 46. A first protruding portion 47 that protrudes in a direction away from the second exterior material 50 and extends linearly is provided at a position between the first protruding portions 47, and the first protruding portion 47 is provided in a circumferential shape along the joint region A1. There is. According to such a power storage element 1, it is suppressed that the heat applied to the junction region A1 is transferred to the region away from the junction region A1 beyond the first protrusion 47 over the entire region of the junction region A1. .. In the region where heat is not transferred, the first exterior material 40 and the second exterior material 50 are not joined. In this way, it is possible to make it difficult for the first exterior material 40 and the second exterior material 50 to be joined in a region away from the joining region A1.

It is possible to make various changes to the above-described embodiment.

For example, in the example shown in FIG. 5, the second exterior material 50 has a flat plate shape. However, not limited to the example shown in FIG. 5, as shown in FIG. 9, the second exterior material 50 includes the second peripheral edge portion 55 and the second bulging portion 56 surrounded by the second peripheral edge portion 55. , May have. In this case, the second bulging portion 56 bulges from the second peripheral edge portion 55 in the direction away from the first exterior material 40. The second bulging portion 56 forms a storage space 7a together with the first bulging portion 46. Further, a part of the region of the second peripheral edge portion 55 is joined to the first peripheral edge portion 45 of the first exterior material 40. In other words, the junction region A1 is a region that overlaps a part of the second peripheral edge portion 55. Further, the joint region A1 surrounds the second bulging portion 56. The distance between the second bulging portion 56 and the joint region A1 is 2.0 mm or more.

Since the second exterior material 50 has the second peripheral edge portion 55 and the second bulging portion 56 surrounded by the second peripheral edge portion 55, the accommodation space 7a of the exterior body 7 can be increased. That is, the electrode body 5 that can be accommodated in the accommodation space 7a can be enlarged. Therefore, the amount of electric power that can be stored in the power storage element 1 can be improved.

Further, in the example shown in FIG. 9, the second exterior material 50 has a second projecting portion 57 projecting in a direction away from the first exterior material 40. The second protruding portion 57 extends linearly along the second peripheral edge portion 55 in a plan view. The second protruding portion 57 is located between the joint region A1 and the second protruding portion 56. The second protruding portion 57 is provided in a circumferential shape along the joint region A1. In other words, the first protruding portion 47 surrounds the second protruding portion 56. The second protruding portion 57 is provided at the same position as the first protruding portion 47 in a plan view.

According to such a second protruding portion 57, similarly to the first protruding portion 47, it is possible to prevent the heat applied to the joint region A1 from being transferred to a region beyond the second protruding portion 57 and away from the joint region A1. Will be done. Therefore, when the joining region A1 is heated by the second protruding portion 57, it is possible to make it difficult for the first exterior material 40 and the second exterior material 50 to be joined in a region away from the intended joining region A1. it can. In particular, since not only the first protruding portion 47 but also the second protruding portion 57 is provided, heat is transferred from both the first exterior material 40 and the second exterior material 50 to the region away from the joint region A1. Can be suppressed.

In the example shown in FIG. 9, the first exterior material 40 has a first protrusion 47, and the second exterior material 50 has a second protrusion 57. However, as in the above-described embodiment, only the first exterior material 40 may have the first protrusion 47, or only the second exterior material 50 has the second protrusion 57. You may. That is, at least one of the first exterior material 40 and the second exterior material 50 may have protrusions 47 and 57. Since at least one of the first exterior material 40 and the second exterior material 50 has the protrusions 47 and 57, when the joint region A1 is heated, in a region away from the intended joint region A1. It is possible to make it difficult for the first exterior material 40 and the second exterior material 50 to be joined.

If the first exterior material 40 and the second exterior material 50, which are not provided with the bulging portion, are provided with the protruding portions, the protruding portions increase the volume occupied by the power storage element 1 in the first direction d1. Therefore, from the viewpoint of volumetric energy density, it is preferable that the first exterior material 40 and the second exterior material 50, which are not provided with the bulging portion, are not provided with the protruding portion. In other words, when the second exterior material 50 is provided with the second protruding portion 57, it is preferable that the second exterior material 50 has the second bulging portion 56.

1 Power storage element 5 Electrode body 6 Tab 7 Exterior body 7a Storage space 10 1st electrode 20 2nd electrode 30 Separator 40 1st exterior material 41 1st metal layer 42 1st resin layer 43 1st insulating layer 45 1st peripheral edge 46 1st bulging portion 47 1st protruding portion 50 2nd exterior material 51 2nd metal layer 52 2nd resin layer 53 2nd insulating layer 55 2nd peripheral edge portion 56 2nd bulging portion 57 2nd protruding portion A1 Joint region

Claims (16)

An exterior body having a first exterior material and a second exterior material,
An electrode body having a plurality of first electrodes and a plurality of second electrodes accommodated and laminated in an accommodation space formed between the first exterior material and the second exterior material is provided.
The first exterior material has a peripheral edge portion and a bulging portion that is surrounded by the peripheral edge portion and bulges from the peripheral edge portion in a direction away from the second exterior material.
The first exterior material and the second exterior material are joined in a joint region that overlaps a part of the peripheral edge portion and surrounds the bulging portion in a circumferential shape.
At least one of the first exterior material and the second exterior material is located at a position between the joint region and the bulging portion in a direction away from the other of the first exterior material and the second exterior material. It has a protruding part that extends linearly,
The protruding portion is a power storage element provided in a circumferential shape along the joint region. The power storage element according to claim 1, wherein the first exterior material has a metal layer and a resin layer laminated on the metal layer and located closer to the second exterior material than the metal layer. The power storage element according to claim 2, wherein the resin layer has thermoplasticity. The power storage element according to any one of claims 1 to 3, wherein the distance between the protruding portion and the joint region is 1.0 mm or less. The power storage element according to any one of claims 1 to 4, wherein the distance between the protruding portion and the joint region is 0.5 mm or more. The power storage element according to any one of claims 1 to 5, wherein the width of the protruding portion is 0.8 mm or more. The power storage element according to any one of claims 1 to 6, wherein the distance between the bulging portion and the joint region is 2.0 mm or more. The power storage element according to any one of claims 1 to 7, wherein the electrode body has a separator arranged between the first electrode and the second electrode. The second exterior material includes a second peripheral edge portion and a second bulging portion that is surrounded by the second peripheral edge portion and bulges from the second peripheral edge portion in a direction away from the first exterior material. And
The power storage element according to any one of claims 1 to 8, wherein the joint region is a region that overlaps a part of the second peripheral edge portion and surrounds the second bulging portion in a circumferential shape. The protrusions are a first protrusion protruding from the first exterior material in a direction away from the second exterior material, and a second protrusion protruding from the second exterior material in a direction away from the first exterior material. The power storage element according to any one of claims 1 to 9, further comprising a part. The method for manufacturing a power storage element according to any one of claims 1 to 10.
A step of forming a protrusion on at least one of the first exterior material and the second exterior material, and
A step of arranging an electrode body having a plurality of first electrodes and a plurality of second electrodes in an accommodation space formed between the first exterior material and the second exterior material.
A step of joining the first exterior material and the second exterior material in a direction in which the protruding portion projects in a direction away from the other of the first exterior material and the second exterior material is provided.
A method for manufacturing a power storage element, wherein the protruding portion is formed in a circumferential shape along a joint region for joining the first exterior material and the second exterior material. The method for manufacturing a power storage element according to claim 11, wherein the protruding portion is formed by embossing. The bulge is formed by embossing and
The method for manufacturing a power storage element according to claim 12, wherein the protruding portion and the bulging portion are formed at the same time. The method for manufacturing a power storage element according to any one of claims 11 to 13, wherein in the step of joining the first exterior material and the second exterior material, the joint region is heated at 200 ° C. or higher. The production of the power storage element according to any one of claims 11 to 14, wherein in the step of joining the first exterior material and the second exterior material, a pressure of 1.5 MPa or more is applied to the joint region. Method. The power storage element according to any one of claims 11 to 15, wherein in the step of joining the first exterior material and the second exterior material, the joint region is heated and / or pressurized for 5 seconds or more. Manufacturing method.

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