JP6837320B2 - Exterior case for power storage device and its manufacturing method - Google Patents

Description

The present invention is for power storage devices such as batteries and capacitors used in portable devices such as smartphones and tablets, hybrid vehicles, electric vehicles, wind power generation, solar power generation, and nighttime electricity storage. Regarding the outer case and its manufacturing method.

In the scope of claims of the present application and in the present specification, the term "substantially rectangular parallelepiped shape" is used to include "substantially cubic shape".

Further, in the scope of claims of the present application and in the present specification, the term "substantially polygonal prism shape" is used to mean "polygonal prism shape having a substantially regular polygonal bottom surface". Further, the term "substantially polygonal prism shape" is used to include the above "substantially rectangular parallelepiped shape".

Further, in the present specification, with respect to the outer case, the term "upper" means the direction from the bottom opening of the outer case toward the top wall of the storage case (upward in FIG. 7), and is "downward". The term means the direction from the top wall of the containment case to the bottom opening (downward in FIG. 7), and the word "horizontal" means the direction parallel to the surface of the top wall of the containment case. The term "vertical" means the direction perpendicular to the surface of the top wall of the containment case.

Further, in the present specification, with respect to the punch, the term "upper" means the direction in which the punch enters the hole of the die during molding (see FIG. 5), and the term "lower" means the above-mentioned upper and true. The word "horizontal" means the direction parallel to the surface of the top wall (molding surface) of the punch, and the word "vertical" means the direction perpendicular to the surface of the top wall of the punch. It means.

Lithium-ion secondary batteries are widely used as a power source for, for example, notebook computers, video cameras, mobile phones, and the like. As the lithium ion secondary battery, a battery having a structure in which the periphery of the battery main body (main body including the positive electrode, the negative electrode and the electrolyte) is surrounded by an exterior material is used. As the exterior material for exteriorizing the power storage device body such as the battery body, for example, an outer layer made of a heat-resistant resin film, an aluminum foil layer, and an inner layer made of a thermoplastic resin film are bonded and integrated in this order. It is known (see Patent Document 1).

The power storage device is the above-mentioned outer case in which the sealing peripheral edge portion (flange portion) is extended from the peripheral edge of the bottom opening of the rectangular parallelepiped-shaped storage case whose bottom surface is open toward the outside in a substantially horizontal direction. The power storage device main body is housed in the storage case, a flat exterior material is superposed on the bottom surface side of the storage case, and the sealing peripheral portion of the exterior case and the peripheral edge portion of the flat exterior material are heat-melted. It is configured to be sealed by being bonded (heat sealed). Leakage of the electrolytic solution can be prevented by sealing with such a heat seal joint.

Japanese Unexamined Patent Publication No. 2005-22336

By the way, the exterior case is obtained by performing molding such as deep drawing on a flat exterior material (see Patent Document 1), and is composed of a pair of side walls and a top wall adjacent to each other in the storage case portion. Since strains are concentrated (concentrated) at the three-sided corners during molding, wrinkles and cracks are likely to occur at the three-sided corners of the outer case, and it is difficult to secure sufficient strength. In particular, when an outer case was obtained by performing deeper molding to further increase the height (depth) of the accommodating case, wrinkles and cracks were generated at the three-sided corners, and the strength was significantly reduced.

The present invention has been made in view of such a technical background, and is capable of sufficiently suppressing the concentration of large strains on the three-sided corners, suppressing the occurrence of wrinkles and cracks, and ensuring sufficient strength. It is an object of the present invention to provide an outer case for a device and a method for manufacturing the same.

In order to achieve the above object, the present invention provides the following means.

[1] A storage case provided with a substantially polygonal prism-shaped storage case having an open bottom surface and a flange portion extending outward in a substantially horizontal direction from the peripheral edge of the opening port on the bottom surface of the storage case. It is an exterior case for devices
Adjacent side walls constituting the storage case are connected to each other via curved corner walls arranged between each other, and each side of the top wall constituting the storage case is an upper side of the side wall and a curved surface, respectively. Each corner edge of the top wall is connected via a ridge line portion, and each corner edge is connected to the upper edge of the corner wall portion via a corner apex portion having a curved surface.
When the radius of curvature of the ridge line portion is "R ₁ " and the radius of curvature of the vertical cross section of the corner apex portion is "R ₂ ", the exterior for a power storage device is characterized in that _{R 1} <R _2. Case.

[2] The exterior case for a power storage device according to item 1 above, wherein the substantially polygonal prism shape is a substantially rectangular parallelepiped shape. That is, in the present invention of [2], a substantially rectangular parallelepiped storage case having an open bottom surface and a flange portion extending outward in a substantially horizontal direction from the peripheral edge of the opening port on the bottom surface of the storage case. The exterior case for a power storage device provided with the above means that the adjacent side walls constituting the storage case are connected to each other via curved corner walls arranged between the storage cases, and the top wall constituting the storage case. The four sides of the top wall are connected to the upper side of the side wall via the ridgeline portion of the curved surface, and the four corner edges of the top wall are the upper edge of the corner wall portion and the corner apex portion having the curved surface, respectively. When the radius of curvature of the ridge line portion is "R ₁ " and the radius of curvature of the vertical cross section of the corner apex portion is "R ₂ ", the relationship is characterized _{by R 1} <R _2. To do.

[3] The power storage device according to item 1 or 2 above, wherein the substantially horizontal edge of the ridge and the edge of the corner apex facing the edge are connected via a transition wall. Exterior case for.

[4] The exterior case for a power storage device according to item 3 above, wherein at least a part of the boundary ridgeline between the transition wall portion and the top wall in a plan view is a curved line that is convex outward.

[5] The exterior case for a power storage device according to item 3 or 4 above, wherein the length of the transition wall portion in the horizontal direction exceeds 0 mm and is 5 mm or less.

[6] Each of the storage case and the flange portion is any one of the above items 1 to 5 made of a laminated material including a metal foil layer and a sealant layer laminated on one surface of the metal foil layer. The exterior case for the power storage device described in the section.

[7] The main body of the power storage device and
An exterior member including the exterior case for a power storage device according to any one of the above items 1 to 6 is provided.
A power storage device characterized in that the power storage device main body is covered with the exterior member.

[8] It has a substantially polygonal pillar-shaped punch that is three-dimensionally formed by pushing the material plate, a die having a substantially polygonal pillar-shaped hole that receives the material plate pushed into the punch, and a hole for inserting the punch. It is a method of manufacturing an outer case for a power storage device by drawing and molding a material plate using a drawing die provided with a blank holder.
A step of sandwiching the material plate between the sandwiching surface around the hole of the die and the sandwiching surface around the hole of the blank holder.
A molding step of inserting the punch through the hole of the blank holder and further inserting the punch into the hole of the die to draw and mold the material plate to obtain an outer case for a power storage device is included.
As the punch, adjacent side walls are connected to each other via curved corner wall portions arranged between each other, and each side of the top wall is connected to the upper side of the side wall via a curved surface ridge line portion. Each corner edge of the top wall is a punch formed by being connected to the upper edge of the corner wall portion via a corner apex portion having a curved surface, and the radius of curvature of the ridge line portion is defined as "S ₁ ". A method for manufacturing an outer case for a power storage device, which comprises using a punch having a relationship of _{S 1} <S ₂ when the radius of curvature of the vertical cross section of the apex of the corner is "S _2".

[9] The method for manufacturing an exterior case for a power storage device according to item 8 above, wherein the substantially polygonal prism shape is a substantially rectangular parallelepiped shape. That is, the present invention of [9] comprises a substantially rectangular parallelepiped punch that is three-dimensionally formed by pushing a material plate, a die having a substantially rectangular parallelepiped hole that receives the material plate pushed into the punch, and the punch. It is a method of manufacturing an outer case for a power storage device by drawing and molding a material plate using a blank holder having a hole to be inserted and a drawing mold provided with the material plate of the hole of the die. The material plate is made by sandwiching the material plate between the surrounding sandwiching surface and the sandwiching surface around the hole of the blank holder, and inserting the punch through the hole of the blank holder and further entering the hole of the die. Including a molding process of drawing and forming an outer case for a power storage device, adjacent side walls are connected as punches via curved corner walls arranged between each other, and four sides of the top wall are formed. , Each of which is connected to the upper side of the side wall via the ridgeline portion of the curved surface, and the four corner edges of the top wall are connected to the upper edge of the corner wall portion via the corner apex portion having a curved surface, respectively. When the radius of curvature of the ridgeline portion is "S ₁ " and the radius of curvature of the vertical cross section of the corner apex portion is "S ₂ ", the punch having the relationship of _{S 1} <S _{2 is used.} It is characterized by being used.

[10] In the punch, the edge in the substantially horizontal direction of the ridge line portion and the edge edge of the corner apex portion facing the edge portion are connected to each other via a transition wall portion in the preceding item 8 or 9. The method for manufacturing an outer case for a power storage device according to the description.

In the inventions of [1] and [2], a curved corner wall portion, a curved ridge line portion, and a curved corner apex portion are provided in the accommodating case portion, and the radius of curvature R ₁ <corner apex portion of the ridge line portion is provided. Since the configuration has a radius of curvature R ₂ of the vertical cross section, it is possible to sufficiently suppress that large strains are concentrated on the three-sided corners of the accommodating case (distortion of the strains), and the three-sided corners. It is possible to provide an outer case having sufficient strength while preventing wrinkles and cracks in the surface. Therefore, it is possible to provide an exterior case having a deep storage case portion.

In the invention of [3], the substantially horizontal edge of the ridgeline portion and the edge of the corner apex facing the edge are connected via the transition wall portion (continuous at the transition wall portion). Therefore, the strain concentrated on the three-sided corners of the storage case can be more sufficiently dispersed, and the strength of the outer case can be more sufficiently secured. Therefore, it is possible to provide an outer case having a deeper storage case portion.

In the invention of [4], since at least a part of the boundary ridgeline between the transition wall portion and the top wall is a curve that is convex outward in a plan view, the stress in the transition wall portion can be further reduced.

In the invention of [5], since the horizontal length of the transition wall portion exceeds 0 mm and is 5 mm or less, the strain concentrated on the three-sided corner portion of the storage case portion can be more sufficiently dispersed. The strength of the outer case can be further improved.

According to the invention of [6], it is possible to provide an outer case having excellent heat sealing property and excellent gas barrier property.

In the invention of [7], since the exterior is covered with an exterior member including an exterior case having sufficient strength to prevent wrinkles and cracks, it is possible to provide a power storage device having excellent durability. Further, since the outer case can be formed with a deeper depth without any problem, for example, the electric capacity (battery capacity, etc.) of the power storage device can be further increased.

In the inventions of [8] and [9], the punch is provided with the corner wall portion of the curved surface, the ridgeline portion of the curved surface, and the corner apex portion of the curved surface, and the radius of curvature of the ridgeline portion S ₁ <the vertical cross section of the corner apex portion. since drawing using a punch having a relationship of the radius of curvature S _2, a large distortion is sufficiently inhibited from concentrating on three sides corners of the housing case portion (to be able to disperse the strain) trihedral corners It is possible to manufacture an outer case for a power storage device having sufficient strength while preventing wrinkles and cracks in the surface.

In the invention of [10], the substantially horizontal edge of the ridgeline portion of the punch and the edge of the angular apex portion facing the edge are connected via the transition wall portion, which is more sufficient. It is possible to manufacture a strong exterior case.

It is an exploded perspective view which shows one Embodiment of the drawing die used by the manufacturing method of this invention. It is a perspective view from the diagonally lower side which shows one corner wall part of a punch and its vicinity. It is a top view which shows one corner apex part of a punch and its vicinity. It is a side view which shows one corner apex part of a punch and its vicinity. It is schematic cross-sectional view which shows the processing state of the exterior material (material plate) using the die for drawing molding of FIG. It is a perspective view which shows one Embodiment of the exterior case for a power storage device of this invention. FIG. 6 is a cross-sectional view taken along the line BB in FIG. FIG. 6 is a perspective view from an obliquely lower side showing one corner wall portion of the storage case and its vicinity in the outer case for a power storage device of FIG. 6 (however, the flange portion is omitted). FIG. 6 is a plan view showing one corner apex of the storage case and its vicinity in the outer case for a power storage device of FIG. 6 (however, the flange portion is omitted). FIG. 6 is a side view showing one corner apex of the storage case and its vicinity in the outer case for a power storage device of FIG. 6 (however, the flange portion is omitted). It is a perspective view from the diagonally lower side which shows one corner wall part of the storage case in the outer case for a power storage device which concerns on another Embodiment of this invention, and the vicinity thereof (however, the flange part is omitted). .. FIG. 11 is a plan view showing one corner apex of the storage case and its vicinity in the outer case for a power storage device of FIG. 11 (however, the flange portion is omitted). FIG. 11 is a side view showing one corner apex of the storage case and its vicinity in the outer case for a power storage device of FIG. 11 (however, the flange portion is omitted). It is sectional drawing which shows an example of the laminated structure of the material plate (exterior material) used in the manufacturing method of this invention. It is sectional drawing which shows one Embodiment of the power storage device which concerns on this invention.

A method for manufacturing an outer case for a power storage device according to the present invention will be described. An embodiment of the draw die 40 used in the present manufacturing method is shown in FIG.

The drawing die 40 is a die having a punch 43 for three-dimensionally forming the material plate 91 by pushing the material plate 91, and a substantially rectangular parallelepiped hole 41a for receiving the material plate 91 pushed into the punch 43. A blank holder 42 having a substantially rectangular parallelepiped hole 42a into which the punch 43 is inserted is provided (see FIG. 1).

The punch 43 has a substantially rectangular parallelepiped shape (see FIG. 1). The punch 43 has four side walls 51, a top wall 52, and a bottom wall 53 (see FIGS. 2 to 4). The side wall 51, the top wall 52, and the bottom wall 53 are all substantially rectangular. In the punch 43, adjacent side walls 51 are connected (continuously connected) via curved corner wall portions 44 arranged between each other, and the four sides (rectangular shape) of the top wall 52 are formed. The four sides) are connected (continuously connected) to the upper side 51a of the side wall 51 via the ridge portion 45 of the curved surface, and the four square edges 52b of the top wall 52 are connected to the corner wall, respectively. It is connected (continuously connected) to the upper edge 44a of the portion 44 via a corner apex portion 46 having a curved surface. The corner wall portion 44, the ridge line portion 45, and the corner apex portion 46 all have a curved surface (curved surface that bulges outward) that is convex outward (see FIGS. 2 to 4). Further, the corner wall portion 44, the ridge line portion 45, and the corner apex portion 46 all form a 1/4 arc (a quarter portion of a circle) in cross-sectional view (FIGS. 2 to 4). reference).

Further, the edge 45c in the horizontal direction of the ridge 45 (the direction parallel to the length direction of the ridge 45) and the edge 46c of the corner apex 46 facing the edge 45c are transition walls. It is connected (continuously connected) via a portion 47. The transition wall portion 47 has a curved surface (curved surface that bulges outward) that is convex outward. The upper edge of the transition wall portion 47 is connected (continuously connected) to the top wall 52, and the lower edge of the transition wall portion 47 is connected (continuously connected) to the side wall 51. (See Figures 2-4). The transition wall portion 47 is configured such that the radius of curvature gradually decreases from the corner apex portion 46 side toward the ridge line portion 45 side.

In the punch 43 of the present embodiment, at least a part of the ridgeline (boundary ridgeline) 54 of the boundary between the transition wall portion 47 and the top wall 52 in a plan view is a curve that is convex outward (curve that bulges outward). ) (See Fig. 3). Further, in the present embodiment, in a plan view, the corner apex portion 46 side of the boundary ridge line 54 is a straight line, and the ridge line portion 45 side of the boundary ridge line 54 is a curve that is convex outward (a curve that bulges outward). ) (See Fig. 3).

In the punch 43 of the present embodiment, at least a part of the ridgeline (boundary ridgeline) 55 of the boundary between the transition wall portion 47 and the side wall 51 in the side view is a curve that is convex upward (curve that bulges upward). (See Fig. 4). Further, in the present embodiment, in the side view, the corner apex portion 46 side of the boundary ridge line 55 is a straight line, and the ridge line portion 45 side of the boundary ridge line 55 is a curved line (curve that bulges upward). (See Fig. 4).

In the punch 43, when the radius of curvature of the vertical cross section of the ridge line portion 45 is “S ₁ ” and the radius of curvature of the vertical cross section of the corner apex portion 46 is “S ₂ ”, the relationship is _{S 1} <S _2. is there. By using the punch 43 having such a relationship, it is possible to sufficiently suppress that a large strain is concentrated on the three-sided corner portion of the accommodating case portion 2, and wrinkles and cracks at the three-sided corner portion are prevented and sufficient. The exterior case 1 having strength can be manufactured.

In the punch 43, the length M of the transition wall portion 47 in the horizontal direction (direction parallel to the length direction of the ridge line portion 45) is preferably more than 0 mm and 6 mm or less (FIGS. 3, 4). reference).

In the punch 43, the radius of curvature (S ₁ ) of the vertical cross section of the ridge line portion 45 is preferably in the range of 0.05 mm to 4 mm (see FIGS. 3 and 4). Further, "S _2- S ₁ " (value obtained by subtracting S _{1 from S 2} ) is preferably in the range of 0.1 mm to 4 mm. _{Further, the radius of curvature (S 3} ) of the horizontal cross section of the corner wall portion 44 is preferably in the range of more than 0 mm and 8 mm or less (see FIG. 4).

In the punch 43, _{it is preferable to adopt a configuration in which the relational expression of M ≧ 2 (S 2} −S ₁ ) / π holds. In this case, the acute angle portion of the punch 43 can be reduced and the force applied at the time of molding can be reduced. It can be sufficiently dispersed without being concentrated, and the moldability can be further improved.

Therefore, the outer case 1 for the power storage device of the present invention can be manufactured as follows by using the draw molding die 40 having the above configuration. First, the material plate 91 is sandwiched between the sandwiching surface 41b around the hole 41a of the die 41 and the sandwiching surface 42b around the hole 42a of the blank holder 42 (sandwiching step). Next, as shown in FIG. 5, the punch 43 is inserted through the hole 42a of the blank holder 42 and further inserted into the hole 41a of the die 41 to draw and shape the material plate 91, as shown in FIG. The exterior case 1 for a power storage device as shown can be manufactured.

In the present embodiment, the material plate (exterior material) 91 is a laminate including a heat-resistant resin layer 92 as an outer layer, a sealant layer 93 as an inner layer, and a metal foil layer 94 arranged between both layers. A material was used (see FIG. 14). Further, in the present embodiment, the material plate (exterior material) 91 has a heat-resistant resin layer (outside) on one surface (upper surface) of the metal foil layer 94 via a second adhesive layer (outer adhesive layer) 95. The layer) 92 is laminated and integrated, and the sealant layer (inner layer) 93 is laminated and integrated on the other surface (lower surface) of the metal foil layer 94 via the first adhesive layer (inner adhesive layer) 96. (See FIG. 14). As the material plate (exterior material) 91, a laminated material including a metal foil layer 94 and a sealant layer (inner layer) 93 laminated on one surface of the metal foil layer 94 may be used. Good.

The obtained exterior case 1 for a power storage device extends from the peripheral edge of a substantially rectangular parallelepiped storage case 2 having an open bottom surface and an opening 13 on the bottom surface of the storage case 2 toward the outside in a substantially horizontal direction. The flange portion 3 is provided (see FIGS. 6 and 7).

The storage case 2 has substantially the same shape as the upper portion of the punch 43 (see FIGS. 6 and 7). That is, the storage case 2 has four side walls 11 and a top wall 12 (see FIGS. 8 to 10). The side wall 11 and the top wall 12 are both substantially rectangular. In the storage case 2, adjacent side walls 11 are connected (continuously connected) via curved corner wall portions 4 arranged between each other, and form four sides (rectangular shape) of the top wall 12. The four sides) are connected (continuously connected) to the upper side 11a of the side wall 11 via the ridgeline portion 5 of the curved surface, and the four corner edges 12b of the top wall 12 are respectively connected to the corner wall. It is connected (continuously connected) to the upper edge 4a of the portion 4 via a corner apex portion 6 having a curved surface. The corner wall portion 4, the ridge line portion 5, and the corner apex portion 6 all have a curved surface (curved surface that bulges outward) that is convex outward (see FIGS. 8 to 10). Further, the corner wall portion 4, the ridge line portion 5, and the corner apex portion 6 all form a 1/4 arc (a quarter portion of a circle) in cross-sectional view (FIGS. 8 to 10). reference).

Further, the edge 5c in the horizontal direction of the ridge 5 (the direction parallel to the length direction of the ridge 5) and the edge 6c of the corner apex 6 facing the edge 5c are transition walls. It is connected (continuously connected) via the part 7. The transition wall portion 7 has a curved surface (curved surface that bulges outward) that is convex outward. The upper edge of the transition wall portion 7 is connected (continuously connected) to the top wall 12, and the lower edge of the transition wall portion 7 is connected (continuously connected) to the side wall 11. (See Figures 8-10). The transition wall portion 7 is configured such that the radius of curvature gradually decreases from the corner apex portion 6 side toward the ridge line portion 5 side.

In the exterior case 1 of the present embodiment, at least a part of the ridgeline (boundary ridgeline) 14 of the boundary between the transition wall portion 7 and the top wall 12 in a plan view is a curved line (bulging outward) that is convex outward. It is a curved line (see FIG. 9). Further, in the present embodiment, in a plan view, the corner apex 6 side of the boundary ridge 14 is a straight line, and the ridge 5 side of the boundary ridge 14 is an outwardly convex curve (a curve that bulges outward). ) (See Fig. 9).

In the exterior case 1 of the present embodiment, at least a part of the ridgeline (boundary ridgeline) 15 of the boundary between the transition wall portion 7 and the side wall 11 in the side view is a curve that is convex upward (curve that bulges upward). (See FIG. 10). Further, in the present embodiment, in the side view, the corner apex portion 6 side of the boundary ridge line 15 is a straight line, and the ridge line portion 5 side of the boundary ridge line 15 is a curved line (curve that bulges upward). (See FIG. 10).

In the exterior case 1, when the radius of curvature of the vertical cross section of the ridge line portion 5 is "R ₁ " and the radius of curvature of the vertical cross section of the corner apex portion 6 is "R ₂ ", the relationship of _{R 1} <R ₂ It is in. Because of this relationship, the exterior case 1 can sufficiently suppress large strains from concentrating on the three-sided corners of the accommodating case 2, prevent wrinkles and cracks at the three-sided corners, and have sufficient strength. It has.

In the exterior case 1, the length L of the transition wall portion 7 in the horizontal direction (direction parallel to the length direction of the ridge line portion 5) is preferably more than 0 mm and 5 mm or less, and in this case, Can disperse the strain concentrated on the three-sided corners of the housing case 2 more sufficiently, and the exterior case 1 having higher strength can be obtained.

In the exterior case 1, the radius of curvature (R ₁ ) of the vertical cross section of the ridge line portion 5 is preferably in the range of 0.1 mm to 4 mm (see FIGS. 9 and 10). Further, "R _2- R ₁ " (value obtained by subtracting R _{1 from R 2} ) is preferably in the range of 0.1 mm to 4 mm. _{The radius of curvature (R 3} ) of the horizontal cross section of the corner wall portion 4 is preferably in the range of 0.1 mm to 8 mm (see FIG. 10).

In the outer case 1, _{it is preferable to adopt a configuration in which the relational expression of L ≧ 2 (R 2} −R ₁ ) / π holds, and by molding so as to have this shape, the force applied at the time of molding is not concentrated. It can be sufficiently dispersed.

FIGS. 11 to 13 show the three-sided corner portion and its vicinity of another embodiment of the outer case 1 for a power storage device according to the present invention. In this embodiment, the configurations other than the transition wall portion 7 are the same as those in the above embodiment. In the above embodiment, the transition wall portion 7 of the accommodation case 2 has a two-stage configuration as shown in FIGS. 8 to 10 (in a plan view, the corner apex portion 6 side of the boundary ridge line 14 is a straight line, and the ridge line at the boundary ridge line 14 is straight. The curve is such that the portion 5 side is convex outward, the corner apex portion 6 side of the boundary ridge line 15 is a straight line, and the ridge line portion 5 side of the boundary ridge line 15 is a curve that is convex upward. However, in this embodiment, the boundary ridge line 14 is a straight line in the plan view, and the boundary ridge line 15 is a straight line in the side view (FIGS. 11 to 13). When the two-stage configuration as in the embodiment is adopted, there is an advantage that the stress in the transition wall portion 7 can be further reduced. Therefore, it is preferable to adopt the configuration of the embodiment, but as shown in FIGS. 11 to 13. It may have a one-stage configuration. Therefore, as a matter of course, the same one-stage configuration may be adopted for the punch 43.

In the manufacturing method according to the above embodiment, the punch 43 has a substantially rectangular parallelepiped shape (see FIG. 1), but may have a substantially polygonal prism shape (for example, a substantially polygonal pillar shape having a low height). Such a substantially polygonal prism shape is not particularly limited, but for example, a substantially pentagonal prism shape, a substantially hexagonal prism shape, a substantially seven-sided prism shape, a substantially octagonal pillar shape, a substantially nine-sided prism shape, and a substantially ten-sided prism shape And so on. In this case, the plan view shape of the hole 41a of the die 41 is the same substantially polygonal shape as the bottom surface of each of these substantially polygonal prism shapes.

Therefore, the following exterior case 1 for a power storage device can be obtained by manufacturing the punch 43 having a substantially polygonal prism shape in the same manner as in the above embodiment. That is, the obtained exterior case 1 for a power storage device has a substantially polygonal pillar-shaped storage case 2 having an open bottom surface and a substantially horizontal outward direction from the peripheral edge of the opening port on the bottom surface of the storage case 2. Adjacent side walls 11 including an extended flange portion 3 and constituting the accommodation case 2 are connected to each other via curved corner wall portions 4 arranged between each other to form the accommodation case 2. Each side of the top wall 12 is connected to the upper side 11a of the side wall 11 via a curved ridge line portion 5, and each square edge 12b of the top wall 12 is connected to the upper edge 4a of the corner wall portion 4, respectively. , The radius of curvature of the vertical cross section of the ridge line portion 5 is set to "R ₁ ", and the radius of curvature of the vertical cross section of the corner apex portion 6 is set to "R ₂ ". When, the configuration is such _{that R 1} <R _2. Since _{there is a relationship of R 1} <R ₂ , the exterior case 1 can sufficiently suppress that large strains are concentrated on the three-sided corners of the accommodating case 2, and wrinkles and cracks at the three-sided corners are prevented. It also has sufficient strength. The substantially polygonal pillar shape of the storage case 2 (for example, a substantially polygonal pillar shape having a low height) corresponds to the substantially polygonal pillar shape of the punch 43 (for example, a substantially polygonal pillar shape having a low height). Become. The substantially polygonal prism shape of the storage case 2 is not particularly limited, but for example, a substantially pentagonal prism shape, a substantially hexagonal prism shape, a substantially seven-sided prism shape, a substantially octagonal pillar shape, a substantially nine-sided prism shape, and substantially ten. Examples include a prismatic shape. For example, when the storage case 2 has a substantially hexagonal column shape, there are 6 corner wall portions 4, 6 corner apex portions 6, and 6 ridge line portions 5.

In the present invention, the sealant layer (inner layer) 93 is provided with excellent chemical resistance against a highly corrosive electrolytic solution used in a lithium ion secondary battery or the like, and the exterior material is heat-sealed. It plays the role of granting.

The resin constituting the sealant layer 93 is not particularly limited, and examples thereof include a thermosetting resin. The heat-sealing resin is not particularly limited, and is, for example, polyethylene, polypropylene, ionomer, ethyl ethylene acrylate (EEA), methyl ethylene acrylate (EAA), methyl ethylene methacrylate resin (EMMA). , Ethylene-vinyl acetate copolymer resin (EVA), maleic anhydride-modified polypropylene, maleic anhydride-modified polyethylene and the like. Above all, the sealant layer 93 is preferably formed of unstretched polyolefin.

The thickness of the sealant layer (inner layer) 93 is preferably set to 15 μm to 30 μm. Sufficient heat seal strength can be ensured by setting it to 15 μm or more, and it contributes to thinning and weight reduction by setting it to 30 μm or less.

In the present invention, as the heat-resistant resin constituting the heat-resistant resin layer (outer layer) 92, a heat-resistant resin that does not melt at the heat-sealing temperature when the exterior material is heat-sealed is used. As the heat-resistant resin, it is preferable to use a heat-resistant resin having a melting point higher than the melting point of the sealant layer 93 by 10 ° C. or more, and it is particularly preferable to use a heat-resistant resin having a melting point higher than the melting point of the sealant layer 93 by 20 ° C. or more. preferable.

The heat-resistant resin layer (outer layer) 92 is not particularly limited, and examples thereof include a polyamide film such as a nylon film and a polyester film, and these stretched films are preferably used. Among them, the heat-resistant resin layer 92 includes a biaxially stretched polyamide film such as a biaxially stretched nylon film, a biaxially stretched polybutylene terephthalate (PBT) film, a biaxially stretched polyethylene terephthalate (PET) film, or a biaxially stretched polyethylene film. It is particularly preferable to use a phthalate (PEN) film. The nylon film is not particularly limited, and examples thereof include a 6-nylon film, a 6,6 nylon film, and an MXD nylon film. The heat-resistant resin layer 2 may be formed of a single layer, or may be formed of, for example, a multi-layer made of a polyester film / polyamide film (a multi-layer made of a PET film / nylon film, etc.). Is also good. In the case of the plurality of layers, it is preferable to arrange the polyester film side on the outermost side. The heat-resistant resin layer 92 may be formed by applying a heat-resistant resin and drying it.

The thickness of the heat-resistant resin layer (outer layer) 92 is preferably 2 μm to 50 μm. When a polyester film is used, the thickness is preferably 5 μm to 40 μm, and when a nylon film is used, the thickness is preferably 15 μm to 50 μm. By setting it to the above-mentioned preferable lower limit value or more, sufficient strength can be secured as an exterior case, and by setting it to the above-mentioned preferable upper limit value or less, the stress at the time of molding can be reduced and the moldability can be improved.

In the present invention, the metal leaf layer 94 plays a role of imparting a gas barrier property to prevent the invasion of oxygen and moisture into the outer case 1. The metal foil layer 94 is not particularly limited, and examples thereof include aluminum foil, SUS foil (stainless steel foil), copper foil, nickel foil, titanium foil, and the like. Among them, aluminum foil is used. preferable. The thickness of the metal foil layer 94 is preferably 15 μm to 100 μm. When it is 15 μm or more, it is possible to prevent the occurrence of pinholes during rolling when manufacturing a metal foil, and when it is 100 μm or less, the stress during molding can be reduced and the moldability can be improved. Above all, the thickness of the metal foil layer 94 is more preferably 15 μm to 45 μm. Further, as the aluminum foil, A8079-O material and A8021-O material specified in JIS H4160: 2006 are suitable.

It is preferable that at least the inner surface (the surface on the side of the second adhesive layer 96) of the metal foil layer 94 is subjected to chemical conversion treatment. By performing such a chemical conversion treatment, it is possible to sufficiently prevent the metal foil surface from being corroded by the contents (battery electrolyte, etc.). Examples of such chemical conversion treatment include chromate treatment and the like.

The first adhesive layer (outer adhesive layer) 95 is not particularly limited, but for example, a polyurethane polyolefin adhesive layer, a polyurethane adhesive layer, a polyester polyurethane adhesive layer, and a polyether polyurethane adhesive layer. And so on. The thickness of the first adhesive layer 95 is preferably set to 1 μm to 6 μm.

The second adhesive layer (inner adhesive layer) 96 is not particularly limited, and for example, those exemplified as the first adhesive layer 95 can be used, but polyolefins with less swelling due to an electrolytic solution can be used. It is preferable to use a system adhesive. Above all, it is particularly preferable to use an acid-modified polyolefin-based adhesive. Examples of the acid-modified polyolefin-based adhesive include maleic acid-modified polypropylene adhesives and fumaric acid-modified polypropylene adhesives. The thickness of the second adhesive layer 96 is preferably set to 1 μm to 5 μm.

FIG. 15 shows an embodiment of the power storage device 30 configured by using the power storage device exterior case 1 of the present invention. The power storage device 30 is a lithium ion secondary battery. In the present embodiment, as shown in FIG. 15, the exterior member 29 is composed of an exterior case 1 for a power storage device and a flat exterior material (a flat one without being molded on the material plate 91) 28. Has been done. Thus, a substantially rectangular parallelepiped power storage device main body (electrochemical element or the like) 31 is housed in the storage recess (storage case 2) of the power storage device exterior case 1 of the present invention, and above the power storage device main body 31. The flat exterior material 28 is arranged with the inner layer 93 side facing inward (lower side), and the peripheral edge portion of the inner layer 93 of the flat exterior material 28 and the flange portion of the exterior case 1 ( The power storage device 30 of the present invention is configured by sealing and sealing the inner layer 93 of the sealing peripheral portion) 3 by heat sealing (see FIG. 15). The inner surface of the accommodating recess of the exterior case 1 is an inner layer (sealant layer) 93, and the outer surface of the accommodating recess is an outer layer (heat-resistant resin layer) 92 (see FIG. 15). ..

In FIG. 15, 39 is a heat-sealed portion in which the peripheral edge portion of the flat exterior material 28 and the flange portion (sealing peripheral edge portion) 3 of the exterior case 1 are joined (fused). In the power storage device 30, the tip of the tab lead connected to the power storage device main body 31 is led out to the outside of the exterior member 29, but the illustration is omitted.

The power storage device main body 31 is not particularly limited, and examples thereof include a battery main body, a capacitor main body, and an electric double layer capacitor main body.

In the above embodiment, the exterior member 29 has a configuration of the exterior case 1 and the flat exterior material 28 (see FIG. 15), but the configuration is not particularly limited to such a configuration, for example. The exterior member 29 may be composed of a pair of exterior cases 1.

Next, specific examples of the present invention will be described, but the present invention is not particularly limited to those of these examples.

<Example 1>
Using the draw forming die 40 shown in FIG. 1 provided with the punch 43 having the structure shown in FIGS. 2 to 4, the drawing molding is performed on the material plate (exterior material) 91 by the above-mentioned manufacturing method of the outer case. (See FIG. 5), the outer case 1 for the power storage device shown in FIG. 6 was manufactured. At this time, drawing molding was performed by changing (increasing) the molding depth in units of 3.0 mm to 0.5 mm to obtain an outer case having each molding depth. The drawing depth was increased in 0.5 mm units, and the drawing was completed when pinholes and cracks were found in the outer case.

The outer dimensions of the die and the blank holder used were rectangles having a long side of 120 mm and a short side of 80 mm, and each hole had a long side straight portion of 50.4 mm and a short side straight portion of 29.8 mm. Further, the punch 43 used has a radius of curvature (S _{1 ) of the vertical cross section of the ridge portion 45 of 2.0 mm, a radius of curvature (S 2} ) of the vertical cross section of the corner apex portion 46 of 4.0 mm, and a transition wall portion 47. The length (M) in the horizontal direction was 1.0 mm, and the radius of curvature (S ₃ ) of the horizontal cross section of the corner wall portion 44 was 2.5 mm (see FIGS. 2 to 4).

Further, the material plate (exterior material) 91 used is a 30 μm-thick aluminum foil (aluminum foil of A8021 defined by JIS H4160-2006) 94 on one surface of a urethane adhesive (outer adhesive) 95. A biaxially stretched nylon film 92 having a thickness of 25 μm is bonded to the other surface of the aluminum foil 94 via a two-component curable maleic acid-modified polypropylene adhesive (inner adhesive) 96 to a thickness of 40 μm. It is a laminated material formed by laminating an unstretched polypropylene film 93 (see FIG. 14). The material plate 91 is a rectangle having a long side of 120 mm and a short side of 80 mm, which is the same as the outer dimensions of the die and the blank holder.

In the obtained exterior case 1 for the power storage device, the radius of curvature (R ₁ ) of the vertical cross section of the ridge line portion 5 of the storage case 2 is 2.0 mm, and the radius of curvature (R ₂ ) of the vertical cross section of the corner apex portion 6 is 4. The length (L) of the transition wall portion 7 in the horizontal direction was 1.0 mm at 0 mm (see FIGS. 8 to 10).

<Example 2>
_{The radius of curvature S 1} of the vertical cross section of the ridge 45 of the punch 43 is set to 4.0 mm, the radius of curvature S ₂ of the vertical cross section of the corner apex 46 is set to 4.1 mm, and the radius of curvature S 2 of the vertical cross section of the corner apex 46 is set to 4.1 mm in the horizontal direction of the transition wall portion 47. The outer case 1 for the power storage device shown in FIG. 6 was manufactured in the same manner as in the first embodiment except that the length M of the above was set to 1.0 mm. In the obtained exterior case 1 for a power storage device, the radius of curvature R _{1 of the vertical cross section of the ridge line portion 5 of the storage case 2 is 4.0 mm, the radius of curvature R 2} of the vertical cross section of the corner apex portion 6 is 4.1 mm, and the transition wall. The length L of the portion 7 in the horizontal direction was 1.0 mm (see FIGS. 8 to 10).

<Example 3>
The outer case for the power storage device shown in FIG. 6 is the same as in the first embodiment except _{that S 1} in the punch is set to 0.5 mm, S _{2 is set to 4.0 mm, and M is set to 1.0 mm.} 1 was manufactured. In the obtained electricity storage device for outer case 1, R ₁ of the housing case 2 is 0.5 mm, R ₂ is 4.0 mm, L was 1.0 mm (see Fig. 8-10).

<Example 4>
The exterior case for the power storage device shown in FIG. 6 is the same as in the first embodiment except _{that S 1} in the punch is set to 2.0 mm, S _{2 is set to 2.1 mm, and M is set to 1.0 mm.} 1 was manufactured. In the obtained electricity storage device for outer case 1, R ₁ of the housing case 2 is 2.0 mm, R ₂ is 2.1 mm, L was 1.0 mm (see Fig. 8-10).

<Example 5>
The outer case for the power storage device shown in FIG. 6 is the same as in the first embodiment except _{that S 1} in the punch is set to 2.0 mm, S _{2 is set to 6.0 mm, and M is set to 1.0 mm.} 1 was manufactured. In the obtained electricity storage device for outer case 1, R ₁ of the housing case 2 is 2.0 mm, R ₂ is 6.0 mm, L was 1.0 mm (see Fig. 8-10).

<Example 6>
The outer case 1 for the power storage device shown in FIG. 6 is set in the same manner as in the first embodiment except _{that S 1} in the punch is set to 2.0 mm, S _{2 is set to 4.0 mm, and M is set to 0 mm.} Manufactured. In the obtained electricity storage device for outer case 1, R ₁ of the housing case 2 is 2.0 mm, R ₂ is 4.0 mm, L was 0 mm (see Fig. 8-10).

<Example 7>
The exterior case for the power storage device shown in FIG. 6 is the same as in the first embodiment except _{that S 1} in the punch is set to 2.0 mm, S _{2 is set to 4.0 mm, and M is set to 6.0 mm.} 1 was manufactured. In the obtained electricity storage device for outer case 1, R ₁ of the housing case 2 is 2.0 mm, R ₂ is 4.0 mm, L was 6.0 mm (see Fig. 8-10).

<Comparative example 1>
An exterior case for a power storage device was manufactured in the same manner as in Example 1 except that S ₁ in the punch was set to 2.0 mm, S _{2 was set to 2.0 mm, and M was set to 0 mm.} In the obtained outer case for the power storage device, R ₁ of the storage case was 2.0 mm, R ₂ was 2.0 mm, and L was 0 mm.

<Comparative example 2>
An exterior case for a power storage device was manufactured in the same manner as in Example 1 except that S ₁ in the punch was set to 4.0 mm, S _{2 was set to 2.0 mm, and M was set to 1.0 mm.} In the obtained outer case for the power storage device, R ₁ of the storage case was 4.0 mm, R ₂ was 2.0 mm, and L was 1.0 mm.

The moldability of each of the exterior cases for power storage devices obtained as described above was evaluated based on the following evaluation method. The results are shown in Table 1.

<Formability evaluation method>
The presence or absence of wrinkles, pinholes and cracks in each of the obtained outer cases (each outer case formed by drawing and molding by changing the molding depth in units of 0.5 mm) was examined, and such wrinkles, pinholes and cracks occurred. No "Maximum molding depth (mm)" was investigated and evaluated based on the following criteria. The presence or absence of pinholes and cracks was examined in a dark room by a light transmission method.
(Criteria)
"○" ... The maximum molding depth at which wrinkles, pinholes and cracks do not occur is 6.0 mm or more. "△" ... The maximum molding depth at which wrinkles, pinholes and cracks do not occur is 4.5 mm or more and less than 6.0 mm. "X" ... The maximum molding depth at which wrinkles, pinholes and cracks do not occur is less than 4.5 mm.

As is clear from Table 1, the outer case for the power storage device of Examples 1 to 7 of the present invention obtained by the manufacturing method of the present invention has wrinkles, pinholes and cracks (wrinkles, pinholes and cracks) even after molding with a deep molding depth. It had no cracks) and had excellent moldability. As described above, according to the present invention, it is possible to provide an outer case for a power storage device provided with a deeper storage case portion.

On the other hand, in Comparative Examples 1 and 2 which deviate from the specified range of the present invention, wrinkles, pinholes, and cracks were generated when molding with a deep molding depth was performed.

The outer case for a power storage device according to the present invention and the outer case for a power storage device obtained by the manufacturing method according to the present invention are, for example, as specific examples.
-Used as an exterior case for various power storage devices such as lithium secondary batteries (lithium ion batteries, lithium polymer batteries, etc.), lithium ion capacitors, electric double layer capacitors, and all-solid-state batteries.

1 ... Exterior case for power storage device 2 ... Storage case 3 ... Flange 4 ... Corner wall 4a ... Upper edge 5 ... Ridge 5c ... Edge 6 ... Corner apex 6c ... Edge 7 ... Transition wall 11 ... Side wall 11a ... Top side 12 ... Top wall 12b ... Square edge 13 ... Bottom opening 14 ... Boundary ridge 29 ... Exterior member 30 ... Power storage device 31 ... Power storage device body 40 ... Drawing mold 41 ... Die 41a ... Hole 41b ... Pinching Surface 42 ... Blank holder 42a ... Hole 42b ... Pinching surface 43 ... Punch 44 ... Corner wall 44a ... Upper edge 45 ... Ridge 45c ... Edge 46 ... Corner apex 46c ... Edge 47 ... Transition wall 51 ... Side wall 51a ... Upper side 52 ... Top wall 52b ... _{Square edge R 1} ... Radius of curvature of the vertical cross section of the ridgeline of the _{outer case R 2} ... Radius of curvature of the vertical cross section of the corner apex of the outer case L ... Horizontal Length in direction S ₁ ... Radius of curvature of the vertical cross section of the ridge of the _{punch S 2} ... Radius of curvature of the vertical cross section of the apex of the corner of the punch M ... Length of the transition wall of the punch in the horizontal direction

Claims (7)

Exterior for power storage device including a substantially polygonal prism-shaped storage case with an open bottom surface and a flange portion extending outward in a substantially horizontal direction from the peripheral edge of the opening port on the bottom surface of the storage case. It ’s a case,
Adjacent side walls constituting the storage case are connected to each other via curved corner walls arranged between each other, and each side of the top wall constituting the storage case is an upper side of the side wall and a curved surface, respectively. Each corner edge of the top wall is connected via a ridge line portion, and each corner edge is connected to the upper edge of the corner wall portion via a corner apex portion having a curved surface.
The curvature radius of the ridge portion and "R _1", when the radius of curvature of the vertical cross section of the angle apex and "R _2", Ri near relation R ₁ <R _2,
The substantially horizontal edge of the ridge and the edge of the corner apex facing the edge are connected via the transition wall.
An exterior case for a power storage device, characterized in that at least a part of the boundary ridgeline between the transition wall portion and the top wall in a plan view is a curved line that is convex outward. The exterior case for a power storage device according to claim 1, wherein the substantially polygonal prism shape is a substantially rectangular parallelepiped shape. The exterior case for a power storage device according to claim 1 or 2, wherein the length of the transition wall portion in the horizontal direction exceeds 0 mm and is 5 mm or less. The storage case and the flange portion are all made of a laminated material including a metal foil layer and a sealant layer laminated on one surface of the metal foil layer, according to any one of claims 1 to 3. The exterior case for the storage device described. Power storage device body and
An exterior member including the exterior case for a power storage device according to any one of claims 1 to 4 is provided.
A power storage device characterized in that the power storage device main body is covered with the exterior member. A substantially polygonal pillar-shaped punch that is three-dimensionally formed by pushing the material plate, a die having a substantially polygonal pillar-shaped hole that receives the material plate pushed into the punch, and a blank holder having a hole for inserting the punch. It is a method of manufacturing an outer case for a power storage device by drawing and molding a material plate using a drawing die equipped with.
A step of sandwiching the material plate between the sandwiching surface around the hole of the die and the sandwiching surface around the hole of the blank holder.
A molding step of inserting the punch through the hole of the blank holder and further inserting the punch into the hole of the die to draw and mold the material plate to obtain an outer case for a power storage device is included.
As the punch, adjacent side walls are connected to each other via curved corner wall portions arranged between each other, and each side of the top wall is connected to the upper side of the side wall via a curved ridge line portion. Each corner edge of the top wall is a punch formed by being connected to the upper edge of the corner wall portion via a corner apex portion having a curved surface, and the radius of curvature of the ridge line portion is set to "S". ₁ The radius of curvature of the vertical cross section of the apex of the corner is set to "S". ₂ When "S ₁ <S ₂ Using punches that are related to
In the punch, the substantially horizontal edge of the ridge and the edge of the corner apex facing the edge are connected via the transition wall.
A method for manufacturing an outer case for a power storage device, characterized in that at least a part of a boundary ridgeline between the transition wall portion and the top wall in a plan view is a curved line that is convex outward. The method for manufacturing an outer case for a power storage device according to claim 6, wherein the substantially polygonal prism shape is a substantially rectangular parallelepiped shape.

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