JP4830289B2 - Secondary battery - Google Patents

Description

  The present invention relates to a secondary battery.

  In recent years, various secondary batteries have been proposed as power sources for portable devices and portable devices, and as power sources for electric vehicles and hybrid vehicles. (For example, refer to Patent Document 1 and Patent Document 2).

JP 2001-176487 A JP 2004-31167 A

  The secondary batteries of Patent Document 1 and Patent Document 2 may be used as a single battery, but when used as a power source for an electric vehicle or a hybrid vehicle, a large number of secondary batteries are arranged and connected. Use. Thus, when arranging a large number of batteries, it is preferable to provide a cooling passage through which cooling air flows between adjacent secondary batteries and cool each battery appropriately.

  In the secondary battery of Patent Literature 1, a large number of protrusions are formed on the outer wall surface (long side surface) of the battery case (battery case). For this reason, when arranging a plurality of secondary batteries so that the long side surfaces are in contact with each other, a gap is provided between adjacent secondary batteries by bringing the protrusions into contact with each other, and cooling air flows through the gap. It can be a cooling passage. Thereby, each secondary battery can be cooled appropriately.

  Also in the secondary battery 500 of Patent Document 2, as shown in FIG. 11, the battery case 501 (the battery case 502) has an uneven wall portion 510 whose outer wall surface (long side surface) forms an uneven shape. As shown in FIG. 12, the concavo-convex wall portion 510 has a concave portion 513 having a flat plate shape, and a convex portion 511 including a large number of contact portions 512 that are substantially columnar and project in the thickness direction. Therefore, as shown in FIG. 14, when a plurality of secondary batteries 500 are arranged so that the contact parts 512 of the concavo-convex wall part 510 are in contact with each other, a cooling passage is provided between adjacent secondary batteries 500. Since R can be provided, each secondary battery 500 can be appropriately cooled. In the secondary battery 500, as shown in FIG. 13, a battery case main body portion 514 made of resin and a multilayer coating 515 made of resin such as PP, aluminum foil or the like are integrally formed to form an uneven wall portion 510. I am doing.

  By the way, in recent years, in order to reduce the mounting space of the secondary battery, there is an increasing demand for downsizing of the secondary battery. However, in order to reduce the battery without reducing the battery capacity, The thickness of the wall must be reduced. However, in a secondary battery, the internal pressure may increase with charge / discharge, so if the thickness of the wall of the battery case is simply reduced, the strength that can withstand the increase in internal pressure may not be maintained. .

Specifically, for example, in the secondary battery 500 of Patent Document 2, as shown in FIG. 13, it is considered that the plate thickness T2 of the uneven wall portion 510 of the battery case 501 is reduced to T1. For example, as described above, in order to reduce the thickness of the concavo-convex wall portion 510 to T1 without changing the cooling passage R when the plurality of secondary batteries 500 are arranged, the thickness of the battery case body portion 514 is set to (T2 -T1) must be thinned. However, in this case, as indicated by a virtual line in the figure, the thickness of the entire concave portion 513 having a flat plate shape is reduced to S, and there is a possibility that the strength that can withstand the increase in internal pressure cannot be maintained.

  For example, the uneven wall portion 510 (recessed portion 513) expands due to the increase in internal pressure, and the gap between the adjacent secondary batteries 500 may decrease, and the cooling passage R may not be secured. Therefore, there is a possibility that the secondary battery cannot be cooled appropriately. Furthermore, there is a risk that the uneven wall portion 510 (battery case 501) may be damaged because the uneven wall portion 510 cannot withstand the increased internal pressure.

  The present invention has been made in view of the current situation, and when a plurality of secondary batteries are arranged in contact with each other, each secondary battery can be appropriately cooled. And it aims at providing the secondary battery which can be reduced in size, ensuring the intensity | strength of a battery case appropriately.

The solution is a secondary battery comprising one or more power generation elements and a rectangular parallelepiped battery case that houses the power generation elements, and the battery case forms at least a part of the battery case. A concavo-convex wall portion that is relatively thick and has a convex portion extending in a battery height direction perpendicular to the thickness direction of the concavo-convex wall portion; and a thickness that is thinner than the convex portion and the battery height Recesses extending in the direction have concavo-convex wall portions alternately arranged in a direction perpendicular to the battery height direction , and the protrusions are arranged when the battery cases are arranged in contact with each other. A contact portion that contacts the battery case, the contact portion being formed integrally with the convex portion , wherein the concave portion has a flat inner wall surface and an outer wall surface in the battery height direction . extending a groove, fracture shape in the direction perpendicular to the cell height direction, the upper A secondary battery which forms an arcuate groove convex towards the inside of the battery case.

  The secondary battery of this invention has the uneven | corrugated wall part which makes at least one part of a battery case. The convex portion of the concavo-convex wall portion includes a contact portion that contacts another battery case when the battery cases are arranged in contact with each other. For this reason, when battery cases are brought into contact with each other and a plurality of secondary batteries are arranged, a gap can be provided between adjacent secondary batteries. Hereinafter, it is also referred to as a cooling passage. Thereby, even when arranging a plurality of secondary batteries, each battery can be appropriately cooled.

Thereon, the recess of the uneven wall, without the inner wall surface flat surface, the outer wall surface, a groove extending in the cell height direction, breaking the shape in the direction orthogonal to the cell height direction, of the battery case It has an arcuate groove that is convex inward. That is, the concave portion has a form in which the thickness increases from the midpoint of the arc of the concave groove toward both ends. The concave portion having such a form is relatively strong even if the thickness of the midpoint position of the arc of the concave groove is reduced, and therefore deformation of the battery case due to the internal pressure of the battery can be suppressed. In addition, since the concave groove can be used as a cooling passage, the cooling passage can be sufficiently ensured even if the protruding height of the convex portion (contact portion) is low. Therefore, by reducing the protruding height of the convex portion (contact portion), the thickness of the uneven wall portion of the battery case can be reduced, so that the battery can be miniaturized accordingly.

Note that the power generation element is disposed in the battery case in order to perform the function of the battery, and includes, for example, an electrode, a separator, an electrolytic solution, and the like.
Moreover, as a form of a contact part, the elongate contact part extended in a battery height direction ( direction where a ditch | groove extends) with a fixed protrusion height is mentioned, for example. Further, as the contact portion, a large number of columnar bodies may be arranged in a dotted pattern along the battery height direction (the direction in which the groove extends).

Further, in the above secondary battery, at least the uneven wall portion of the battery case is formed by resin injection molding, and the uneven wall portion is formed by the resin flowing in the battery height direction. It is preferable that the secondary battery be made.

  In the secondary battery of the present invention, at least the uneven wall portion of the battery case is formed by resin injection molding. When an uneven wall (including a battery case) is injection molded, if the thickness of the uneven wall is made too thin, the flow path of the injected resin (specifically, the cross section orthogonal to the resin flow direction) ) Is too small, and there is a risk that the injection molding cannot be performed properly.

On the other hand, in the secondary battery of the present invention, as described above, of the concave and convex wall portions of the battery case, with respect to the thin concave portion, the inner wall surface is a flat surface and the outer wall surface extends in the battery height direction . It is a ditch | groove, Comprising: The fracture | rupture shape of the direction orthogonal to a battery height direction is made into the arc-shaped ditch | groove which protrudes toward the inner side of a battery case. That is, the shape of the concave portion is a shape in which the thickness increases from the midpoint of the arc of the concave groove toward both ends. In addition, when the injection molding is performed, in the uneven wall portion, the direction in which the resin flows is the battery height direction in which the groove extends. For this reason, even if the thickness of the center point of the arc of the groove is reduced, the cross-sectional area of the flow path of the injected resin (the cross-sectional area of the cross section perpendicular to the battery height direction through which the resin flows) is reduced. It can be secured relatively large.

Furthermore, among the molding dies, the mold convex part that molds the concave part of the concave-convex wall part becomes closer to the mold concave part that molds the convex part of the concave-convex wall part. It becomes an arc shape in which the dimension in the thickness direction (vertical direction in the figure) over the cross section perpendicular to the flowing direction is increased. For this reason, the resin flowing through the position of the mold concave portion (the flow of the resin is good because the cross-sectional area is larger than the position of the mold convex portion) can easily flow into the position of the mold convex portion. Accordingly, the injected resin can be appropriately poured also into the position of the mold convex portion for molding the concave portion of the concave-convex wall portion.
Therefore, by providing an arc-shaped concave groove in the concave portion and reducing the protruding height of the convex portion (contact portion), it is possible to appropriately injection-mold the concave-convex wall portion (including the battery case) having a reduced thickness. Therefore, a battery including a resin battery case can be easily downsized.

Furthermore, in the secondary battery according to any one of the above, the contact portion may be a secondary battery arranged in a dotted pattern along the battery height direction .

In the secondary battery of the present invention, the contact portions are arranged in a dotted pattern along the battery height direction ( direction in which the convex portion extends). For this reason, when the secondary battery is arranged in contact with another secondary battery at the contact portion, it is also between the contact portions adjacent to each other in the battery height direction ( direction in which the convex portion extends). A cooling passage can be provided. Thereby, the cooling property of a secondary battery can be made favorable.

  Furthermore, in any one of the above secondary batteries, at least the uneven wall portion of the battery case is formed by resin injection molding, and at least the outer wall surface side of the uneven wall portion is made of a metal foil. The secondary battery may be provided with a metal layer having an uneven shape along the outer wall surface.

  In a secondary battery including a resin battery case, there is a problem that water vapor, oxygen gas, hydrogen gas, and the like permeate the battery case and gradually leak to the outside over a long period of time. In particular, in a nickel metal hydride storage battery, hydrogen gas permeates through the resin battery case and leaks to the outside. When the hydrogen gas in the battery decreases, the capacity balance between the positive electrode and the negative electrode is lost, and the battery characteristics are remarkably reduced. There was a problem that would decrease. On the other hand, the secondary battery of the present invention includes a metal layer made of a metal foil at least on the outer wall surface side of the uneven wall portion. Thus, by providing the metal layer on the outer wall surface side of the battery case, hydrogen gas or the like can be prevented from passing through the wall portion of the battery case and leaking outside.

  By the way, in the conventional secondary battery 500 (refer FIG. 11), as shown in FIG. 12, FIG. 13, the metal layer 515c (multilayer film containing the metal layer 515c) is formed in the outer wall surface 510b side of the uneven | corrugated wall part 510 by insert molding. 515) is molded, but there are cases where it cannot be molded properly. Specifically, the outer wall surface 510b of the concavo-convex wall portion 510 includes a concave portion 513 having a flat plate shape, and a convex portion 511 including a large number of abutting portions 512 that are substantially cylindrical and project in the thickness direction. Yes. Therefore, when molding, the multilayer film 515 including the metal layer 515c is placed on the mold for molding the concave-convex shape of the concave-convex wall portion 510, and the injected resin is injected into the mold concave portion for molding the contact portion 512. At the same time, a small cylindrical contact portion 512 is formed by pressing the multilayer film 515 including the metal layer 515c. However, since the multilayer film 515 including the metal layer 515c is not sufficiently deformed along the mold recess, the contact portion 512 may not be formed into an appropriate shape.

In contrast, in the secondary battery of the present invention, as described above, concave portions of the concavo-convex wall, an outer wall surface, a groove extending in the cell height direction, breaking in the direction orthogonal to the cell height direction The shape forms an arc-shaped groove that is convex toward the inside of the battery case. Since the protruding height of the convex portion (contact portion) can be reduced by providing the concave groove, the inserted metal layer (multilayer film including the metal layer) is made of gold corresponding to the shape of the convex portion (contact portion). It becomes easy to deform along a cylindrical concave portion of a small mold. Furthermore, by making the concave groove in an arc shape, the inserted metal layer (multilayer film including the metal layer) can be easily deformed along the mold corresponding to the concave groove. Therefore, it is possible to appropriately shape an uneven wall portion (including a battery case) including a metal layer (a multilayer film including a metal layer) having an uneven shape along the outer wall surface on the outer wall surface by insert molding. It becomes.

  In addition, as metal foil which makes a metal layer, aluminum foil can be used suitably, for example. Further, on the outer wall surface side of the concavo-convex wall portion, not only a metal layer but also a multilayer film in which a metal layer and a resin layer are laminated (for example, a three-layer structure in which a metal layer is disposed between two polypropylene layers). A multilayer film) may be provided.

Furthermore, in any one of the above secondary batteries, at least the uneven wall portion of the battery case is formed by resin injection molding, and at least the outer wall surface side of the uneven wall portion is made of a metal foil. Preferably, the secondary battery includes a metal layer having an uneven shape along the outer wall surface, and the contact portion has an elongated shape extending in the battery height direction with a constant protruding height.

As described above, when a battery case having a contact portion having a small cylindrical shape is formed, the inserted metal layer (multilayer film including the metal layer) is not sufficiently deformed along the mold recess. In some cases, the contact portion cannot be formed into an appropriate shape.
On the other hand, in the secondary battery of the present invention, the contact portion has an elongated shape that extends in the battery height direction ( direction in which the convex portion extends) with a constant protruding height. Accordingly, since the concave portion of the mold corresponding to the contact portion can be enlarged in the battery height direction in which the convex portion extends, the inserted metal layer (multilayer film including the metal layer) is It becomes easy to deform along the mold. Thereby, it becomes easy to shape | mold the injected resin also into the uneven | corrugated shape along the said metal mold | die. Therefore, a battery case including a metal layer (a multilayer film including a metal layer) on the outer wall surface of the concavo-convex wall portion can be appropriately formed by insert molding.

In addition, as one of the above secondary battery manufacturing methods, the method includes a molding step of molding at least the concavo-convex wall portion of the battery case by resin injection molding. In the molding step, in the battery height direction , It is preferable to use a method for manufacturing a secondary battery in which a resin is poured to form the recess.

As described above, the secondary battery of the present invention has a configuration in which the concave portion of the concave-convex wall portion becomes thicker toward the both ends from the midpoint of the arc of the concave groove. On the other hand, in the molding process of the present invention, the resin is poured in the battery height direction in which the recess extends to form the recess, so that the injection is performed even when the thickness of the midpoint position of the arc of the recess is thinned. Since the cross-sectional area of the resin flow path (the cross-sectional area of the cross section perpendicular to the battery height direction through which the resin flows) can be secured relatively large, injection molding can be performed appropriately. Therefore, according to the manufacturing method of the present invention, the thin uneven wall portion (battery case including the wall) can be appropriately formed, so that the battery including the resin battery case can be easily downsized.

  Furthermore, in the method for manufacturing a secondary battery described above, in the forming step, a metal layer made of metal foil (or a multilayer film including the metal layer) is inserted, and at least the uneven wall portion of the battery case is inserted. It is preferable to use a method for manufacturing a secondary battery in which the metal layer having an uneven shape along the outer wall surface is integrally formed on the outer wall surface side.

  As described above, conventionally, when a battery case having an abutting portion having a small columnar shape is formed, the inserted metal layer (multilayer film including the metal layer) is formed by injecting resin into the abutting portion. In this case, the resin cannot be deformed along the small cylindrical concave portion of the mold corresponding to the shape of the mold, and the injected resin may not be molded into the concave and convex shape.

  On the other hand, in the secondary battery of the present invention, as described above, the protrusion height of the convex portion (contact portion) can be lowered by the amount of the concave groove provided in the concave portion of the concave and convex wall portion. For this reason, when the metal layer is integrally formed at least on the outer wall surface side of the concavo-convex wall portion of the battery case by the manufacturing method of the present invention, even when the contact portion is a small cylindrical protrusion, the inserted metal layer (Multilayer film including a metal layer) can be easily deformed along a small cylindrical mold concave portion of the mold corresponding to the shape of the contact portion. Furthermore, since the concave groove is formed in an arc shape, the inserted metal layer (multilayer film including the metal layer) can be easily deformed along the mold corresponding to the concave groove. Accordingly, the injected resin can be appropriately formed into a concavo-convex shape along the mold, and a metal layer (including a metal layer) that appropriately forms a concavo-convex shape along the outer wall surface on the outer wall surface side of the concavo-convex wall portion. Multilayer film) can be formed integrally.

Furthermore, in the method for manufacturing a secondary battery described above, in the forming step, the contact portion is formed into an elongated shape extending in the battery height direction with a constant protrusion height; It is preferable to do this.

As described above, conventionally, when a battery case having an abutting portion having a small columnar shape is formed, the inserted metal layer (multilayer film including the metal layer) is formed by injecting resin into the abutting portion. In this case, the resin cannot be deformed along the small cylindrical concave portion of the mold corresponding to the shape of the mold, and the injected resin may not be molded into the concave and convex shape.
On the other hand, in the manufacturing method of the present invention, the contact portion is formed into an elongated shape extending in the battery height direction ( direction in which the convex portion extends) with a constant protrusion height. That is, the mold concave portion corresponding to the contact portion is enlarged in the battery height direction in which the convex portion extends. As a result, the inserted metal layer (multilayer film including the metal layer) can be easily deformed along the mold by the injected resin, and the injected resin is also formed into an uneven shape along the mold. It becomes easy. Therefore, according to the manufacturing method of the present invention, a battery case including a metal layer (a multilayer film including a metal layer) on the outer wall surface of the concavo-convex wall portion can be appropriately formed.

  Next, embodiments (Examples 1 and 2) of the present invention will be described with reference to the drawings.

  The secondary battery 100 of the first embodiment is a nickel-metal hydride storage battery including a battery case 101 having a battery case 102 and a lid body 103 as shown in FIGS. The lid 103 is made of resin, has a substantially rectangular plate shape, and is provided with a safety valve 122 and a temperature sensor mounting hole 124. The safety valve 122 operates when the internal pressure of the battery case 101 exceeds a predetermined value, discharges internal gas (hydrogen gas or the like) to the outside, and suppresses an increase in internal pressure. A temperature sensor (not shown) can be inserted into the temperature sensor mounting hole 124 so that the temperature of the battery can be detected. The battery case 102 has a substantially rectangular box shape and includes an uneven wall portion 110 having an outer wall surface 110b having an uneven shape, which will be described in detail later.

As shown in FIG. 2, the inside of the battery case 101 (the battery case 102) is partitioned into six spaces by a partition wall portion 130. In each space, an electrode plate group 150 (positive electrode 151, negative electrode 152, separator 153) and an electrolytic solution (not shown) are arranged. The electrode plate group 150 and the electrolytic solution (not shown) correspond to power generation elements.
As the positive electrode 151, for example, an electrode plate including an active material containing nickel hydroxide and an active material support such as foamed nickel can be used. As the negative electrode 152, for example, an electrode plate containing a hydrogen storage alloy as a negative electrode constituent material can be used. As the separator 153, for example, a non-woven fabric made of synthetic fibers subjected to a hydrophilic treatment can be used. As the electrolytic solution, for example, an alkaline aqueous solution containing KOH and having a specific gravity of 1.2 to 1.4 can be used.

Here, the uneven wall portion 110 of the battery case 102 will be described in detail.
As shown in FIG. 3, the concavo-convex wall portion 110 is made of a resin, and includes a resin main body portion 114 having a concavo-convex concavo-convex surface 114b and a multilayer film 115 provided on the concavo-convex surface 114b. As shown in FIG. 4, the multilayer film 115 has a three-layer structure, and in order from the uneven surface 114b side, a first resin layer 115b made of polypropylene, a metal layer 115c made of aluminum foil, and a second resin made of polypropylene. Layer 115d.

  As described above, when the wall of the battery case is made of resin, there is a problem that water vapor, oxygen gas, hydrogen gas, etc. permeate the battery case and gradually leak to the outside over a long period of time. In particular, in the nickel-metal hydride storage battery such as the secondary battery 100 of the first embodiment, when the hydrogen gas passes through the resin battery case and leaks to the outside, the hydrogen gas in the battery decreases. There was a problem that the balance of the capacity of the negative electrode was lost and the battery characteristics were significantly deteriorated. On the other hand, in the secondary battery 100 of the first embodiment, as described above, the uneven wall portion 110 has the multilayer film 115 including the metal layer 115c arranged on the uneven surface 114b of the resin main body portion. I am doing. Thus, by providing the metal layer 115 c on the uneven wall portion 110, hydrogen gas or the like can be prevented from passing through the uneven wall portion 110 of the battery case 101 and leaking outside.

  Furthermore, as shown in FIGS. 3 and 4, the uneven wall portion 110 includes a convex portion 111 having a relatively thick wall and a concave portion 113 having a wall thickness that is thinner than the convex portion 111. The convex portion 111 and the concave portion 113 extend in a predetermined direction orthogonal to the thickness direction (specifically, as shown in FIG. 1B, the battery height direction Y (vertical direction in the drawing)), and the predetermined direction Are arranged alternately in the battery width direction X (specifically, as shown in FIG. 1B).

  As shown in FIG. 3, the convex portion 111 has a substantially cylindrical shape on the outer wall surface 110 b side of the concavo-convex wall portion 110, and includes a large number of contact portions 112 protruding in the thickness direction of the concavo-convex wall portion 110. The contact portions 112 are arranged in a dotted pattern along the battery height direction Y. As will be described in detail later, the contact portion 112 is located at a position where the secondary battery 100 contacts the contact portion 112 of another secondary battery 100 when the plurality of secondary batteries 100 are arranged in contact with each other. Is arranged (see FIG. 5).

  As shown in FIGS. 3 and 4, the recess 113 has a concave portion 113 b extending in the battery height direction Y at a portion forming the inner wall surface 110 c of the uneven wall portion 110 forming a flat surface and a portion forming the outer wall surface 110 b. There is no. The groove 113b has a rupture shape in a direction perpendicular to the battery height direction Y (thickness direction of the concavo-convex wall portion 110, vertical direction in FIG. 4) protruding toward the inner side (inner wall surface 110c side) of the battery case 101. It has an arc shape.

  Here, the secondary battery 100 of the first embodiment will be described in detail in comparison with the conventional secondary battery 500. As shown by a two-dot chain line in FIG. 4, in the conventional secondary battery 500, the thickness of the concavo-convex wall portion 510 is T2, whereas in the secondary battery 100 of the first embodiment, the thickness of the concavo-convex wall portion 110. Is T1 thinner than T2. Specifically, in the secondary battery 100 according to the first embodiment, the thickness of the inner wall surface side of the uneven wall portion is not uniformly reduced, but the protruding height of the contact portion 112 is set to the conventional secondary battery 500. The thickness of the concavo-convex wall portion 110 is reduced by making it lower than the protruding height of the contact portion 512 by (T2-T1).

  By the way, only by reducing the protruding height of the contact portion 112, the cooling passage R (see FIG. 5) when the plurality of secondary batteries 100 are arranged becomes smaller than the conventional secondary battery 500, and cooling is performed. There is concern about the worsening of sex. However, in the first embodiment, the cooling passage R is supplemented by providing the concave 113 with the concave 113b as described above. For this reason, in the secondary battery 100 of the first embodiment, as will be described later, the same cooling performance as that of the conventional secondary battery 500 is ensured.

  Here, FIG. 5 shows a state in which a plurality of secondary batteries 100 are arranged with the concavo-convex wall portions 110 of the battery case 101 in contact with each other, and when a plurality of conventional secondary batteries 500 are arranged (FIG. 14). Reference) and will be described. In addition, as shown in FIG.1 (b), the secondary battery 100 has the positioning convex part 117 and the positioning recessed part 118 for positioning with the other secondary battery 100 on the outer wall surface 110b of the uneven | corrugated wall part 110. As shown in FIG. And have. The positioning convex portion 117 has a cylindrical shape protruding in the thickness direction of the concave-convex wall portion 110 (the direction orthogonal to the paper surface in FIG. 1B). The positioning concave portion 118 is a cylindrical bottomed hole and has a size capable of inserting the positioning convex portion 117. Accordingly, the plurality of secondary batteries 100 are arranged in such a manner that the positioning convex portions 117 are inserted into the positioning concave portions 118 of the other secondary batteries 100.

  When a plurality of secondary batteries 100 are arranged as described above, the contact portion 112 of the concavo-convex wall portion 110 contacts the contact portion 112 of another secondary battery 100 as shown in FIG. Thereby, the cooling passage R can be provided between the adjacent secondary batteries 100. Here, as can be seen from a comparison between FIG. 5 and FIG. 14, the secondary battery 100 of Example 1 was able to secure a cooling passage R having the same size as that of the conventional secondary battery 500. . This is because the recessed groove 113b is provided instead of lowering the protruding height of the contact portion 112.

  Moreover, in the secondary battery 100 of the first embodiment, as in the conventional secondary battery 500, as shown in FIGS. 1 (b) and 3, the contact portion 112 is arranged along the battery height direction Y. They are lined up in a dotted pattern. As a result, the cooling passage R can be provided not only in the battery height direction Y (the direction perpendicular to the paper surface in FIG. 5) in which the concave groove 113b extends, but also in the battery width direction X (the left-right direction in FIG. 5). .

  Therefore, for example, when the cooling air is blown in the battery height direction Y (the direction orthogonal to the paper surface in FIG. 5), the cooling air not only flows in the battery height direction Y along the concave groove 113b, but also The battery flows in the battery width direction X (left and right direction in FIG. 5) so as to go around the contact portion 112. For this reason, since the uneven | corrugated wall part 110 can be cooled over substantially the whole surface, the coolability of the secondary battery 110 becomes favorable.

  However, since the thickness of the concave portion is reduced by providing the concave groove 113b in the concave portion 113, there is a concern that the strength of the concave and convex wall portion 110 is reduced and the secondary battery 110 cannot withstand the increase in internal pressure. On the other hand, in the first embodiment, as shown in FIG. 4, with respect to the recess 113 of the concavo-convex wall portion 110, the portion forming the inner wall surface 110c is made flat and the portion forming the outer wall surface 110b is inside the battery case 101 ( The cross-sectional shape has a convex arc shape toward the inner wall surface 110c side. That is, the concave portion 113 is configured such that the thickness increases from the midpoint F of the arc of the concave groove 113b toward both ends. The recess 113 having such a configuration is relatively strong even when the thickness of the midpoint F of the arc of the recess 113b is reduced to S, and thus the strength capable of withstanding the increase in the internal pressure of the secondary battery 110. Can be secured.

  As described above, in the secondary battery 100 of Example 1, the thickness of the concavo-convex wall 110 could be reduced by (T2-T1) compared to the conventional secondary battery 500. Therefore, compared with the conventional secondary battery 500, the battery thickness (dimension in the vertical direction in FIG. 1A) is reduced by 2 × (T2−T1), thereby realizing downsizing. . Moreover, the cooling property of the secondary battery 100 can be improved while adequately ensuring the strength of the battery case 101 (specifically, the strength of the uneven wall portion 110).

Next, a method for manufacturing the secondary battery 100 of the first embodiment will be described.
First, a resin film made of polypropylene and a metal foil made of aluminum are prepared. Next, a multilayer film 115 having a three-layer structure including the first resin layer 115b, the metal layer 115c, and the second resin layer 115d is formed by bonding a resin film to the front and back surfaces of the metal foil and roll forming. did.

  Next, the battery case 102 was integrally formed by an insert molding method. Specifically, for example, at the site where the concavo-convex wall portion 110 is molded, as shown in FIG. 6 (a), the mold 10 on the outer wall surface 110b side and the mold 20 on the inner wall surface 110c side are used as molds. Prepared. The mold 10 includes a mold recess 11 that molds the convex shape of the convex portion 111, a mold concave portion 12 that molds a substantially cylindrical shape of the contact portion 112 of the convex portion 111, and a concave groove of the concave portion 113. The mold convex part 13 which shape | molds is provided.

  Next, as shown in FIG. 6A, in the state where the multilayer film 115 is placed on the mold 10, a molten resin (in the first embodiment, A polymer alloy made of polypropylene and polyphenylene ether was injected. The molten resin is injected so as to flow in a direction in which the mold concave portion 11 and the mold convex portion 13 extend (a direction orthogonal to the paper surface in FIG. 6A).

  At this time, the multilayer film 115 is pushed and expanded to the mold 10 side (lower side in FIG. 6A) by the injected resin, and the mold recesses 11 and 12 and the mold protrusion 13 of the mold 10 are spread. Along with this, it will be deformed into irregularities. Thereby, the injected resin can be formed into a concavo-convex shape along the mold concave portions 11 and 12 and the mold convex portion 13 of the mold 10. That is, as shown in FIG. 6 (b), it is possible to form the concavo-convex wall portion 110 having the convex portion 111 including the abutting portion 112 and the concave portion 113 and having the multilayer film 115 laminated on the outer wall surface 110b side. .

  By the way, in manufacturing the conventional secondary battery 500, when the battery case 502 of the battery case 501 is integrally formed by the insert molding method, the shape of the contact portion 512 is made of the inserted multilayer film 515 by the injected resin. In some cases, the contact portion 512 cannot be formed into an appropriate shape. . On the other hand, in the first embodiment, since the protruding height of the abutting portion 112 is lowered, the depth of the mold recess 12 for forming the protruding shape of the abutting portion 112 as compared with the conventional mold. Is getting shallower. Furthermore, since the fracture surface shape of the concave groove 113b is an arc shape, the inserted multilayer film 115 can be easily deformed along the mold convex portion 13 for molding the concave groove 113. Therefore, in the first embodiment, the inserted multilayer film 115 can be appropriately deformed along the uneven shape of the mold 10.

  Moreover, in the first embodiment, the thickness of the concavo-convex wall portion 110 is set to T1, which is thinner than the thickness T2 of the conventional concavo-convex wall portion 510. Here, for example, in order to reduce the thickness T2 of the concavo-convex wall portion 510 to T1 while maintaining the size of the cooling passage R, the thickness of the resin main body portion 514 is changed to (1) as shown by a one-dot chain line in FIG. It is conceivable that the thickness is uniformly reduced by T2-T1). However, in this case, the dimension in the thickness direction applied to the cross section of the flow path of the injection resin (the cross section orthogonal to the direction in which the resin flows) is the overall dimension S in the portion where the thinnest recess is formed. It becomes small (thin). That is, since the cross-sectional area of the flow path of the injection resin is reduced as a whole in the portion where the concave portion is formed, the injected resin may not flow properly.

  On the other hand, in the secondary battery 100 of the first embodiment, as shown in FIG. 4, the outer wall surface 110 c of the recess 113 is formed as a concave groove 113 b having an arc cross section, and the protruding height of the contact portion 112 is reduced. While ensuring the cooling passage R, the thickness of the concave wall portion 110 is reduced to T1. For this reason, as shown in FIG. 6, the dimension in the thickness direction (vertical direction in the figure) applied to the cross section of the flow path of the injection resin (cross section orthogonal to the direction in which the resin flows) is It becomes smaller (thinner) to S, but increases from the midpoint F of the arc toward both ends. That is, a relatively large cross-sectional area of the flow path of the injection resin can be ensured.

Furthermore, the mold convex part 13 is a dimension in the thickness direction (vertical direction in the figure) applied to the cross section (cross section orthogonal to the resin flowing direction) of the flow path of the injection resin as it approaches the mold concave parts 11 and 12. It has an arc shape that increases. For this reason, the resin flowing through the positions of the mold concave portions 11 and 12 (the flow of the resin is good because the cross-sectional area is larger than the position of the mold convex portion 13) easily flows into the position of the mold convex portion 13. .
Accordingly, the injected resin can be appropriately poured into the position of the mold convex portion 13 for molding the concave portion 113 in the flow path of the injected resin.

As described above, in Example 1, it was possible to appropriately form the battery case 102 having the thin uneven wall portion 110 by the insert molding method.
After that, as shown in FIG. 2, the electrode plate group 150 (the positive electrode 151, the negative electrode 152, and the separator 153) is disposed in the six spaces partitioned by the partition wall 130 of the battery case 102, and an electrolytic solution (not shown). ) Was injected. Next, the secondary battery 100 including the battery case 101 is completed by integrating the lid 103 including the safety valve 122 and the battery case 101 by heat welding.

  Next, the secondary battery 200 of Example 2 will be described with reference to the drawings. The secondary battery 200 of the second embodiment is different from the secondary battery 100 of the first embodiment in the shape of the uneven wall portion of the battery case, and the other portions are the same. Accordingly, in the following description, the uneven wall portion different from that of the first embodiment will be mainly described, and description of similar portions will be omitted or simplified.

  As shown in FIG. 7, the uneven wall portion 210 of the secondary battery 200 is made of a resin, and includes a resin main body 214 having an uneven surface 214b and a multilayer film 215 provided on the uneven surface 214b. ing. As shown in FIG. 8, the multilayer film 215 has a three-layer structure as in the secondary battery 100 of Example 1, and in order from the concave and convex surface 214b side, the first resin layer 215b made of polypropylene and an aluminum foil. A metal layer 215c and a second resin layer 215d made of polypropylene. As described above, by providing the metal layer 215c on the uneven wall portion 210, hydrogen gas or the like in the battery can be prevented from passing through the uneven wall portion 210 and leaking outside.

  Further, as shown in FIGS. 7 and 8, the uneven wall portion 210 has a convex portion 211 having a relatively thick wall and a concave portion 213 having a wall thickness smaller than that of the convex portion 211. The convex portion 211 and the concave portion 213 are in a predetermined direction orthogonal to the thickness direction (specifically, the battery height direction Y (vertical direction in FIG. 1B) as in the secondary battery 100 of Example 1). ) And are alternately arranged in a direction orthogonal to the predetermined direction (specifically, in the same manner as the secondary battery 100 of Example 1, the battery width direction X (left and right direction in FIG. 1B)). .

  Unlike the convex portion 111 of the first embodiment, the convex portion 211 has an elongated shape extending in the battery height direction Y with a certain protruding height on the outer wall surface 210b side of the concave-convex wall portion 210 as shown in FIG. A contact portion 212 is included. As will be described in detail later, in the same manner as the contact portion 112 of the first embodiment, the contact portion 212 also includes other secondary batteries 200 when the battery cases 201 are arranged in contact with each other. It arrange | positions in the position contact | abutted with the contact part 212 of the battery 200 (refer FIG. 9).

  As shown in FIG. 7 and FIG. 8, the recess 213 has a flat surface where the inner wall surface 210c of the uneven wall portion 210 forms a flat surface and the battery wall 210b corresponds to the battery. A concave groove 213b extending in the height direction Y is formed. The groove 213b has a rupture shape in a direction perpendicular to the battery height direction Y (thickness direction of the concavo-convex wall portion 210, vertical direction in FIG. 8) protruding toward the inner side (inner wall surface 210c side) of the battery case 201. It has an arc shape.

  As shown in FIG. 8, also in the secondary battery 200 of the second embodiment, the thickness of the concavo-convex wall portion 210 is as thin as T1 as in the secondary battery 100 of the first embodiment (in the conventional secondary battery 500, The thickness of the concavo-convex wall portion 510 is T2) that is thicker than T1. More specifically, the uneven wall is not formed by uniformly reducing the wall thickness of the uneven wall portion on the inner wall surface side, but by reducing the protruding height of the contact portion in the same manner as the secondary battery 100 of Example 1. The thickness of the portion 210 is reduced to T1. Here, only by lowering the protrusion height of the contact portion, the cooling passage R becomes smaller (narrower), but in the second embodiment, as described above, the concave groove 213 is provided with the concave groove 213b. The cooling passage R is supplemented.

Here, FIG. 9 shows a state in which a plurality of secondary batteries 200 are arranged with the concavo-convex wall portions 210 of the battery case 201 in contact with each other. Note that the secondary battery 200 of the second embodiment also has a plurality of secondary batteries 200 in the form in which the positioning convex portions 117 are inserted into the positioning concave portions 118 of the other secondary batteries 200, similarly to the secondary battery 100 of the first embodiment. The secondary batteries 200 are arranged (see FIG. 1B).
When a plurality of secondary batteries 200 are arranged as described above, the contact portions 212 of the concavo-convex wall portion 210 contact the contact portions 212 of the other secondary batteries 200 as shown in FIG. Thereby, the cooling passage R can be provided between the adjacent secondary batteries 200. As can be seen from a comparison between FIG. 9 and FIG. 5, the secondary battery 200 of the second embodiment is also of the same level as the secondary battery 100 of the first embodiment (therefore, the same level as the conventional secondary battery 500). Since the cooling passage R of a magnitude | size is ensured, each secondary battery 200 can be cooled appropriately.

  However, since the concave portion 213 is provided with the concave groove 213b, the thickness of the concave portion is reduced. Therefore, there is a concern that the strength of the concave and convex wall portion 210 is reduced and the internal pressure of the secondary battery 210 cannot be increased. On the other hand, in the second embodiment, as shown in FIG. 8, the concave portion 213 of the concave and convex wall portion 210 has a flat shape in the same manner as the concave portion 113 of the first embodiment, and the outer wall surface 210b. The cross-sectional shape that forms a convex arc shape toward the inner side (inner wall surface 210c side) of the battery case 201 is formed. That is, the concave portion 213 is configured such that the thickness increases from the midpoint F of the arc of the concave groove 213b toward both ends. The concave portion 213 having such a configuration is relatively strong even if the thickness of the midpoint F of the arc of the concave groove 213b is reduced to S, so that it can withstand the increase in internal pressure of the secondary battery 200. Can be secured.

  As described above, also in the secondary battery 200 of the second embodiment, the thickness of the uneven wall portion 210 can be reduced by (T2-T1) as compared with the conventional secondary battery 500. Therefore, compared with the conventional secondary battery 500, the battery thickness (dimension in the vertical direction in FIG. 1A) is reduced by 2 × (T2−T1), thereby realizing downsizing. . In addition, the secondary battery 200 can be appropriately cooled while appropriately ensuring the strength of the battery case 201 (specifically, the strength of the uneven wall portion 210).

Next, a method for manufacturing the secondary battery 200 of the second embodiment will be described.
First, in the same manner as in Example 1, a multilayer film 215 having a three-layer structure including the first resin layer 215b, the metal layer 215c, and the second resin layer 215d was formed. Next, as in Example 1, the battery case 202 was integrally molded by an insert molding method. In addition, in the secondary battery 200 of this Example 2, since only the shape of an uneven | corrugated wall part differs compared with the secondary battery 100 of Example 1, the shape of the metal mold | die which molds this differs.

  Specifically, as shown in FIG. 10 (a), the mold 50 on the outer wall surface 210b side and the mold 60 on the inner wall surface 210c side are used as the molds at the site where the uneven wall portion 210 is molded. It was. The mold 50 is provided with a mold concave portion 51 that molds the convex shape of the convex portion 211 including the contact portion 212 and a mold convex portion 53 that molds the concave groove of the concave portion 213. In the second embodiment, as shown in FIG. 10A, after the multilayer film 215 is placed on the mold 50, the fusion is performed between the mold 60 and the multilayer film 215 in the same manner as in the first embodiment. The resin thus obtained (also in Example 2, a polymer alloy made of polypropylene and polyphenylene ether) was injected.

  At this time, the multilayer film 215 is expanded to the mold 50 side (lower side in FIG. 10A) by the injected resin, and along the mold recess 51 and the mold protrusion 53 of the mold 50. , Will be deformed into irregularities. Thereby, the injected resin can be formed into a concavo-convex shape along the mold concave portion 51 and the mold convex portion 53 of the mold 50. That is, as shown in FIG. 10 (b), it is possible to form the concavo-convex wall portion 210 having the convex portion 211 including the abutting portion 212 and the concave portion 213 and having the multilayer film 215 laminated on the outer wall surface 210b side. .

  By the way, in the uneven | corrugated wall part 110 of Example 1, as shown in FIG. 3, the contact part 112 comprises the substantially cylindrical small protrusion, and these are arranged in a dotted pattern along the battery height direction Y. It was to so. Therefore, in Example 1, as shown in FIG. 6, in the mold 10 on the outer wall surface 110 b side of the concavo-convex wall portion 110, the mold concave portion 11 that molds the protruding shape of the contact portion 112 has a substantially cylindrical shape. It becomes a small dent.

  On the other hand, in the present Example 2, as shown in FIG. 7, the contact part 212 is made into the elongate shape extended in the battery height direction Y by fixed protrusion height. Moreover, although not shown, a plurality of contact portions 212 are not arranged in the battery height direction Y, but in the battery height direction Y, from one end portion of the concavo-convex wall portion 210 to the other end portion. Until then, it was set as the form extended linearly continuously. That is, the convex portion 211 is configured to extend at a certain height from the vicinity of one end portion of the uneven wall portion 210 to the vicinity of the other end portion in the battery height direction Y.

For this reason, as shown in FIG. 10 (a), in the mold 50 on the outer wall surface 210b side of the concavo-convex wall section 210, the mold recess 51 for forming the protruding shape of the contact section 212 has a constant depth. It becomes a large dent extending in the height direction Y (direction orthogonal to the paper surface in the drawing). Thereby, the inserted multilayer film 215 is easily deformed along the mold recess 51, and the injected resin is easy to flow in the battery height direction Y (direction perpendicular to the paper surface in the drawing). Therefore, in this Example 2, the moldability of the concavo-convex wall portion (battery case) is better than that in Example 1.
Thereafter, the secondary battery 200 can be manufactured by the same procedure as in the first embodiment.

In the above, the present invention has been described with reference to the first and second embodiments. However, the present invention is not limited to the above-described embodiments, and it can be applied as appropriate without departing from the scope of the present invention. Nor.
For example, in the first and second embodiments, the multilayer films 115 and 215 are provided on the uneven wall portions 110 and 210, but the multilayer films may not be provided.
In the first and second embodiments, the multilayer films 115 and 215 are provided on the concave and convex surfaces 114b and 214b of the resin main body portions 114 and 214, but are provided on the inner side surfaces (inside the battery) of the resin main body portions 114 and 214. You may do it.

  Further, in Example 2, the contact portion 212 is formed in an elongated shape extending in the battery height direction Y with a constant protruding height, and from the vicinity of one end of the concavo-convex wall portion 210 in the battery height direction Y. It was set as the form extended continuously linearly to the other edge part vicinity. That is, the convex portion 211 is configured to extend at a certain height from the vicinity of one end portion of the uneven wall portion 210 to the vicinity of the other end portion in the battery height direction Y. However, the present invention is not limited to such a configuration, and a plurality of elongated contact portions extending in the battery height direction Y with a fixed protrusion height may be arranged in the battery height direction Y.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the secondary battery 100 concerning Example 1, (a) is a top view, (b) is a side view. 1 is a diagram showing the inside of a secondary battery 100 according to Example 1, and corresponds to a cross-sectional view taken along line AA of FIG. 1 is a cutaway perspective view of an uneven wall portion 110 of a battery case 101 according to Example 1. FIG. 3 is a cross-sectional view of the concavo-convex wall portion 110 of the battery case 101 according to Example 1, and corresponds to a view taken in the direction of arrow B in FIG. It is a figure which shows a mode when the some secondary battery 100 is arranged, and is equivalent to sectional drawing concerning the thickness direction of the uneven | corrugated wall part 110. FIG. It is explanatory drawing explaining the manufacturing method of the battery case 102 concerning Example 1. FIG. 6 is a cutaway perspective view of an uneven wall portion 210 of a battery case 201 according to Example 2. FIG. It is sectional drawing of the uneven | corrugated wall part 210 of the battery case 201 concerning Example 2, and is equivalent to the C arrow line view of FIG. It is a figure which shows a mode when the some secondary battery 200 is arranged, and is equivalent to sectional drawing concerning the thickness direction of the uneven | corrugated wall part 210. FIG. It is explanatory drawing explaining the manufacturing method of the battery case 202 concerning Example 2. FIG. It is a figure which shows the conventional secondary battery 500, (a) is a top view, (b) is a side view. FIG. 6 is a cutaway perspective view of an uneven wall portion 510 of a conventional battery case 501. It is sectional drawing of the uneven | corrugated wall part 510 of the conventional battery case 501, and is equivalent to the arrow D figure of FIG. It is a figure which shows a mode when the some secondary battery 500 has been arranged, and is equivalent to sectional drawing concerning the thickness direction of the uneven | corrugated wall part 510. FIG.

Explanation of symbols

100, 200 Secondary battery 101, 201 Battery case 102, 202 Battery case 110, 210 Uneven wall portion 110b, 210b Outer wall portion 110c, 210c Inner wall portion 111, 211 Protruding portion 112, 212 Abutting portion 113, 213 Recessed portion 113b, 213b Concave groove 114, 214 Resin body 115, 215 Multilayer film 115c, 215c Metal layer

Claims (5)

One or more power generation elements;
A battery case having a rectangular parallelepiped shape for accommodating the power generation element;
A secondary battery comprising:
The battery case is
An uneven wall portion forming at least a part of the battery case,
A relatively thick wall, and a protrusion extending in the battery height direction perpendicular to the thickness direction of the uneven wall;
Thicker than the convex portion is thin, and a recess extending the battery height direction, has an uneven wall portion formed by alternately arranged in the direction orthogonal to the cell height direction,
The protrusion includes a contact portion that is in contact with another battery case when the battery cases are arranged in contact with each other, and is formed integrally with the protrusion .
The recess is
The inner wall is flat,
The outer wall surface, a groove extending in the cell height direction, breaking the shape of the direction orthogonal to the cell height direction, a secondary battery which forms the groove of arcuate convex toward the inside of the battery case . The secondary battery according to claim 1,
At least the uneven wall portion of the battery case is formed by resin injection molding,
The concavo-convex wall portion is a secondary battery formed by resin flowing in the battery height direction . The secondary battery according to claim 1 or 2, wherein
The contact portion is a secondary battery that is arranged in a dotted pattern along the battery height direction . The secondary battery according to any one of claims 1 to 3,
At least the uneven wall portion of the battery case is formed by resin injection molding,
A secondary battery comprising a metal layer made of a metal foil and having an uneven shape along the outer wall surface at least on the outer wall surface side of the uneven wall portion. The secondary battery according to claim 1 or 2 , wherein
At least the uneven wall portion of the battery case is formed by resin injection molding,
At least on the outer wall surface side of the concavo-convex wall portion, a metal layer made of a metal foil and having a concavo-convex shape along the outer wall surface,
The contact portion is a secondary battery having an elongated shape extending in the battery height direction with a constant protrusion height.

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