JP6770919B2 - Secondary battery and manufacturing method of secondary battery - Google Patents

Description

The present invention relates to a secondary battery in which a battery film is arranged between a battery case and an electrode body, and a method for manufacturing the secondary battery.

As a battery having a battery film between the battery case and the electrode body of the secondary battery, for example, the secondary battery described in Patent Document 1 is known.
The secondary battery described in Patent Document 1 includes a film for a battery having an insulating property between an electrode body and a battery case. The battery film mechanically and electrically separates the outer peripheral surface of the electrode body from the inner wall surface of the battery case. This battery film is a polarizing film. The battery film is arranged in a direction orthogonal to the stretching direction, which is the direction in which the battery film is wound around the electrode body, and a direction in which the long side direction of the wide surface of the battery case coincides with each other. That is, this secondary battery is configured by inserting an electrode body in which a battery film is arranged on the outer periphery into a battery case.

Japanese Unexamined Patent Publication No. 2016-62645

By the way, as shown in FIG. 7, the thin and elastically deformable battery film 400 maintains a bag shape capable of accommodating an electrode body because its ends and the like are fixed by heat welding. For example, the battery film 400 capable of accommodating an electrode body has a pair of long side surfaces 442 that face each other when one film is folded back, and both sides of the long side surface 442 that are orthogonal to the folding line. It is provided with a short side surface 443 provided. Then, the short side surfaces 443 of the pair of long side surfaces 442 facing each other are folded so as to overlap each other, and the fixing portion 401 is formed by heat welding at the overlapping portion. However, since the battery film 400 is made of a thin film, if too much heat is applied, fusion holes 402 are generated in the fixed portion 401, burrs that cause cracks are generated in the fixed portion 401, and distortion that occurs in the bag shape is caused. The resulting stress or the like may cause cracks 403 in the fixed portion 401, making it impossible to properly maintain electrical insulation.

The present invention has been made in view of such circumstances, and an object of the present invention is a secondary battery in which the insulation property of a battery film is preferably maintained between an electrode body and a battery case, and the second. The purpose is to provide a method for manufacturing a next battery.

The secondary battery for solving the above problems is a secondary battery in which a film is arranged between the electrode body and the battery case, and the battery case has a rectangular opening in which the electrode body is inserted. The film has rounded corners and is made of resin, and has a first surface facing one side of two opposing sides of the battery case and a second surface facing the first surface. Surface, a folded surface provided between the first surface and the second surface arranged in a row, and the first surface, the second surface, and the second surface parallel to the row direction. An end portion provided adjacent to each side of the folded surface and having an end portion extending to a position protruding from the width of the battery case, and an end portion adjacent to the first surface. Is the first end portion, and the first end portion has an inclination angle in the direction of the first surface with respect to the extension line of the boundary line from the end point of the boundary line between the first surface and the folded surface. The end portion adjacent to the second surface is the second end portion, and the second end portion is from the end point of the boundary line between the second surface and the folded surface. It has an inclined side having an inclined side in the direction of the second surface with respect to the extension line of the boundary line, and the inclined side of the inclined side of the first end portion and the inclined side of the inclined side of the second end portion Are different angles.

According to such a configuration, it is not necessary to perform processing such as heat welding on the film to form a bag shape before inserting the electrode body into the battery case. More specifically, by inserting a film that is not formed into a bag shape into the battery case together with the electrode body, the edge of the film is guided to the inner wall surface of the battery case by the inclination angle and bends, so that the film becomes the electrode body. It will be placed between the battery case and the battery case. As a result, since the film is not heat-welded, there is no possibility that through holes will be generated in the heat-welded portion, and there is no possibility that a crack will be generated in the heat-welded restraint portion due to stress caused by distortion of the bag shape or the like. Therefore, the insulating property of the battery film is preferably maintained between the electrode body and the battery case.

Further, when the electrode body is inserted into the battery case, the timing at which the end portion bends along the inner wall surface of the battery case is different. Therefore, even if the ends face each other, the bent state is different, so that there is a high possibility that the ends do not collide with each other and are suitably overlapped with each other.

The secondary battery for solving the above problems is a secondary battery in which a film is arranged between the electrode body and the battery case, and the battery case has a rectangular opening into which the electrode body is inserted. The film has rounded corners and is made of resin, and has a first surface facing one side of two opposing sides of the battery case and a second surface facing the first surface. Surface, a folded surface provided between the first surface and the second surface arranged in a row, and the first surface, the second surface, and the second surface parallel to the row direction. An end portion provided adjacent to each side of the folded surface and having an end portion extending to a position protruding from the width of the battery case, and an end portion adjacent to the first surface. Is the first end portion, and the first end portion has an inclination angle in the direction of the first surface with respect to an extension line of the boundary line from the end point of the boundary line between the first surface and the folded surface. The end portion adjacent to the second surface is the second end portion, and the second end portion is the end point of the boundary line between the second surface and the folded surface. A side having an inclined side having an inclination angle in the direction of the second surface with respect to an extension line of the boundary line, and a side of the opening where the first end portion and the second end portion face each other. The two corners at both ends of the battery have different rounded curvatures.

According to such a configuration, it is not necessary to perform processing such as heat welding on the film to form a bag shape before inserting the electrode body into the battery case. More specifically, by inserting a film that is not formed into a bag shape into the battery case together with the electrode body, the edge of the film is guided to the inner wall surface of the battery case by the inclination angle and bends, so that the film becomes the electrode body. It will be placed between the battery case and the battery case. As a result, since the film is not heat-welded, there is no possibility that through holes will be generated in the heat-welded portion, and there is no possibility that a crack will be generated in the heat-welded restraint portion due to stress caused by distortion of the bag shape or the like. Therefore, the insulating property of the battery film is preferably maintained between the electrode body and the battery case.

Further, since the timing at which the end portion of the film is bent along the roundness is different at the two corners of the opening of the battery case, even if the ends are opposed to each other, the bent state is different, so that the end portion is bent. The possibility that they will overlap with each other without colliding with each other is increased.

As a preferred configuration, the inclination angles of the inclined sides of the first end portions on both sides of the first surface are the same, and the inclination angles of the inclined sides of the second end portions on both sides of the second surface are the same. The angle.
According to such a configuration, the inclination angle of each inclined side of the end portion of the same surface becomes the same angle, so that the film can be easily processed.

As a preferred configuration, the end adjacent to the folded surface has an edge on an extension of the boundary.
According to such a configuration, the width of the end portion adjacent to the folded surface is the same as the width of the folded surface, so that interference with the battery case and interference with other ends is reduced, and the battery case is affected. Easy to place.

As a preferred configuration, the end adjacent to the folded surface has one or more notches extending in a direction orthogonal to the row direction.
If there is no notch in the end and the folded surface is curved, it becomes difficult to bend the end adjacent to the folded surface in the direction of the folded surface. In this regard, according to such a configuration, since the end portion has one or more notches orthogonal to the row direction, even if the folded surface is curved in the row direction, such a curvature is angled between the cuts. By making and absorbing, the end can be bent in the direction of the folded surface.

As a preferred configuration, the resin is any one of polypropylene (PP), polyphenylene ether (PPE) and polyethylene (PE), or a combination of at least two of PP, PPE and PE.

According to such a configuration, the battery film can be made to have insulating property and chemical resistance.
As a preferred configuration, the secondary battery is a lithium ion secondary battery.

According to such a configuration, a resin battery film can be arranged between the electrode body of the lithium ion secondary battery and the battery case.
A method for manufacturing a secondary battery that solves the above problems is a method for manufacturing a secondary battery in which a film is arranged between an electrode body and a battery case, and the electrode body is inserted into the battery case. The film has a rounded corner at the corner of the rectangular opening, and the film is made of a resin, and has a first surface facing one of two opposing side surfaces of the battery case and the first surface. A second surface facing the surface, a folded surface provided between the first surface arranged in a row and the second surface, and the first surface parallel to the row direction. The first surface has end portions that are adjacent to each other on both sides of the second surface and the folded surface and that extend to a position that extends beyond the width of the battery case. The end portion adjacent to the surface is the first end portion, and the first end portion is the direction of the first surface with respect to the boundary line from the end point of the boundary line between the first surface and the folded surface. The end portion adjacent to the second surface is the second end portion, and the second end portion is the end point of the boundary line between the second surface and the folded surface. To the step of arranging the film between the opening of the battery case and the electrode body, which has an inclined side having an inclination angle in the direction of the second surface with respect to the boundary line. By inserting the electrode body into the opening of the battery case while facing the tip surface of the electrode body and the folded surface of the film, the first end portion and the second end portion of the film are separated from each other at different timings. The step of bending along the roundness and the step of arranging the film between the electrode body and the battery case by inserting the electrode body into the opening of the battery case are provided.

According to such a method, it is not necessary to process the film by heat welding or the like before inserting the electrode body into the battery case to form a bag shape. More specifically, by inserting a film that is not formed into a bag shape into the battery case together with the electrode body, the edge of the film is guided to the inner wall surface of the battery case by the inclination angle and bends, so that the film becomes the electrode body. It will be placed between the battery case and the battery case. As a result, since the film is not heat-welded, there is no possibility that through holes will be generated in the heat-welded portion, and there is no possibility that a crack will be generated in the heat-welded restraint portion due to stress caused by distortion of the bag shape or the like. Therefore, the insulating property of the battery film is preferably maintained between the electrode body and the battery case.

As a preferred method, in the step of arranging the film, the film is pre-wound around the electrode body.
According to such a method, the film can be easily arranged between the battery case and the electrode body.

According to the present invention, the insulating property of the battery film is preferably maintained between the electrode body and the battery case.

The perspective view which shows the disassembled perspective structure about one Embodiment of a secondary battery. Top view showing the structure of the opening on the upper side of the battery case in the same embodiment. The development view which shows the development structure of the battery film in the same embodiment. The flowchart which shows the outline of the manufacturing process of the secondary battery in the same embodiment. The flowchart which shows the procedure of the insertion process of the manufacturing process of a secondary battery in the same embodiment. Top view showing the structure of the opening on the upper side of the battery case for another embodiment of the secondary battery. The perspective view which shows the perspective structure about the form of the battery film of the conventional secondary battery.

An embodiment of the secondary battery 10 will be described with reference to FIGS. 1 to 6. A plurality of the secondary batteries 10 of the present embodiment are connected by a bus bar to form an assembled battery. The assembled battery is mounted on an electric vehicle or a hybrid vehicle to supply electric power to an electric motor or the like. The secondary battery 10 is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery, and is a sealed battery having a rectangular parallelepiped outer shape.

As shown in FIG. 1, the secondary battery 10 includes a rectangular battery case 50 having an opening 53, a lid 20 for sealing the battery case 50, and an electrode body 30 housed inside the battery case 50. And a resin film 40 as a battery film arranged between the electrode body 30 and the battery case 50. The battery case 50 and the lid 20 are made of a metal such as an aluminum alloy. The secondary battery 10 is formed by attaching a lid 20 to the battery case 50 to form a sealed battery case. Further, the secondary battery 10 is provided with two external terminals 21 used for charging and discharging electric power on the lid 20.

As shown in FIG. 2, the battery case 50 has a rectangular bottom surface 52 which is the bottom when viewed from the opening 53, and two side surfaces provided so as to surround the bottom surface 52 and along the long side of the bottom surface 52. It includes a long side surface 51 and two short side surfaces 54 along the short side of the bottom surface 52.

The opening 53 is a rectangular opening into which the electrode body 30 is inserted, and the corners 55 and 56 are rounded, and the lid 20 is combined and welded therein to seal the battery case 50. It will be stopped.

The opening 53 has a width W51 in the longitudinal direction of the rectangular shape and a length L51 in the lateral direction of the rectangular shape. The longitudinal direction of the opening 53 is orthogonal to the winding direction R (see FIG. 1) of the electrode body 30, and the lateral direction is the thickness direction of the flat shape of the electrode body 30 (thickness H30: see FIG. 1). is there. Further, the opening 53 has a rounded radius of curvature R1 (curvature 1 / R1) at the corners 55 and 56. The roundness is a portion where a right angle or the like is replaced with a curve having a minute radius (R). That is, the opening 53 has a width W52 (= width W51-radius of curvature R1 × 2) of a straight line portion excluding the length of the radius of curvature R1 in the longitudinal direction, and the radius of curvature is excluded in the lateral direction. It has a length L52 (= length L51-radius of curvature R1 × 2) of a straight line portion.

As shown in FIG. 1, the electrode body 30 is wound in the winding direction R with a separator sandwiched between the positive electrode plate and the negative electrode plate, and is formed in a flat shape. The positive electrode plate has a core body of the positive electrode and a positive electrode mixture supported on the core body, and the core body of the positive electrode is formed of aluminum or an aluminum alloy. The negative electrode plate has a core body of the negative electrode and a negative electrode mixture supported on the core body, and the core body of the negative electrode is formed of copper or a copper alloy. In the electrode body 30, the positive electrode terminal is connected to the exposed portion on the positive electrode side where the core material of the positive electrode is exposed, and the negative electrode terminal is connected to the exposed portion on the negative electrode side where the core material of the negative electrode is exposed.

The electrode body 30 includes an upper surface 33 and a lower surface 32 located between two long side surfaces 31 and two long side surfaces 31 in a flat shape and folded back in the winding direction R, and two end faces 34 serving as ends of the wound body. ing. The upper surface 33 is a surface facing the lid 20, and the lower surface 32 is a surface facing the bottom surface 52 of the battery case 50. Each of the two long side surfaces 31 is a surface facing the long side surface 51 of the battery case 50. Each of the two end faces 34 is a face facing the short side surface 54 of the battery case 50. Of these, since the distance between the upper surface 33 and the lid 20 is secured by the connection structure between the positive electrode terminal and the negative electrode terminal, it is not necessary to secure the insulating property by interposing the resin film 40. On the other hand, on other surfaces, the distance between the electrode body 30 and the battery case 50 may be extremely short, there is a risk of contact when the electrode body 30 expands, or there is a risk of short circuit due to pinching of foreign matter or the like. Therefore, it is necessary to arrange the resin film 40 for ensuring the insulating property between the electrode body 30 and the battery case 50.

As described above, the battery case 50 and the battery case 20 are made of a conductive aluminum alloy. Therefore, it is necessary to maintain the insulating property between the battery case and the electrode body 30. In particular, when the negative electrode plate of the electrode body 30 is short-circuited to the battery case 50, the battery case 50 may be corroded. Therefore, it is necessary to prevent a short circuit from occurring in the battery case 50 even if inconveniences such as expansion, movement, and invasion of foreign matter occur in the electrode body 30.

Therefore, the resin film 40 secures electrical insulation between the inner wall surface 57 (see FIG. 2) of the battery case 50 and the electrode body 30. The resin film 40 is a film having an insulating property, and is composed of, for example, polypropylene (PP) which is a synthetic resin. The resin film 40 is preferably unstretched PP, and may be polyphenylene ether (PPE), polyethylene (PE), or a combination of at least two of these, such as a polymer alloy. .. Examples of the polymer alloy include a mixture of polypropylene and polyethylene (PP / PE alloy).

The resin film 40 is arranged along the winding direction R of the electrode body 30. More specifically, the resin film 40 has two long side surfaces 31 of the electrode body 30, a lower surface 32 arranged in a row in the winding direction R and sandwiched between the two long side surfaces, and a row direction (rolling). It is arranged so as to face two end faces 34 in a direction orthogonal to the rotation direction R). Therefore, the resin film 40 is interposed between the inner wall surface 57 of the battery case 50 and the outer peripheral surface of the electrode body 30 in the battery case 50 to ensure the insulating property between the battery case 50 and the electrode body 30. To do.

As shown in FIG. 3, the resin film 40 has a wide surface 42 facing the two long side surfaces 51 of the battery case 50, and a first end portion 43A and a first end portion 43A facing the two short side surfaces 54 of the battery case 50. It includes two end portions 43B and a lower end portion 44, and a folded surface 46 facing the bottom surface 52 of the battery case 50. In other words, the wide surface 42 of the resin film 40 faces the long side surface 31 of the electrode body 30, and the first end portion 43A, the second end portion 43B, and the lower end portion 44 face the end surface 34 of the electrode body 30 and are folded back. The surface 46 faces the lower surface 32 of the electrode body 30. Therefore, in the secondary battery, the resin film 40 has a wide surface 42 arranged between the long side surface 51 of the battery case 50 and the long side surface 31 of the electrode body 30, and the short side surface 54 of the battery case 50 and the electrode body 30. The first end portion 43A, the second end portion 43B, and the lower end portion 44 are arranged between the end surface 34, and the folded surface 46 is arranged between the bottom surface 52 of the battery case 50 and the lower surface 32 of the electrode body 30.

The resin film 40 has a bending line 41 between the wide surface 42 and the first and second ends 43A and 43B, respectively. The folding lines 41 and the first and second end portions 43A and 43B, respectively, are provided on both sides (both ends) of the surface 42 wide in the row direction. The bending line 41 is a line that defines the bending direction of the first and second ends 43A and 43B with respect to the wide surface 42, and the first and second ends 43A and 43B are pushed and bent in the direction of the wide surface 42. When the first and second ends 43A and 43B are bent, the wide surface 42 is bent.

Further, the resin film 40 has a folding line 47 between the wide surface 42 and the folded surface 46, respectively. That is, the folded surface 46 is partitioned between the two folding lines 47. The folded surface 46 is provided with the lower end portions 44 at both ends in a direction orthogonal to the row direction (turning direction R), in other words, outside the bending line 41. That is, the lower end portions 44 are provided between the two bending lines 47 on both sides (both ends) in the row direction with respect to the folding surface 46. The lower end portion 44 has a notch extending in a direction orthogonal to the row direction from the bending line 41. As a result, even if the bending line 41 is curved, the lower end portion 44 is deformed by the stress applied to the bent lower end portion 44, and the lower end portion 44 can be appropriately bent.

Subsequently, the sizes of the electrode body 30, the battery case 50, and the resin film 40 will be described with reference to FIGS. 1 to 3.
As shown in FIG. 1, the electrode body 30 has a maximum diameter of L32R, a length of a semicircular portion of the upper surface 33 of "2π × L37R / 2", and a semicircle of the lower surface 32 with respect to the winding direction R. The length of the portion is "2π x L35R / 2", and the length of the long side surface is the length L33 (= L32R-L37R-L35R). Further, the electrode body 30 has a width W30 in the width direction which is orthogonal to the winding direction R, and a thickness H30 between the two long side surfaces 31.

As shown in FIG. 2, the depth of the battery case 50 from the opening 53 to the bottom surface 52 is deeper than the length L32R of the electrode body 30. The longitudinal direction of the opening 53 is a width W51 wider than the width W30 of the electrode body 30. The lateral direction of the opening 53 is a length L51 wider than the thickness H30 of the electrode body 30. Preferably, the width W52 in the longitudinal direction of the opening 53 is a width equal to or greater than the width W30 of the electrode body 30. Further, the length L52 of the opening 53 in the lateral direction may be a width equal to or larger than the width H30 of the electrode body 30.

As shown in FIG. 3, the resin film 40 can be interposed between the electrode body 30 and the battery case 50, and has a size that can be accommodated in the battery case 50 by folding the end portion. The resin film 40 has a maximum length L40 in the row direction and a maximum width W40 in the width direction orthogonal to the row direction in the unfolded state. For example, when the resin film 40 is wound tightly around the electrode body 30, the distance H40 between the two wide surfaces 42 is substantially the same as the thickness H30, and the diameter L45R of the semicircular portion of the folded surface 46 is the diameter L35R. The maximum length L42R in the winding direction R is substantially the same as the length L32R.

The maximum length L40 is a length that can be wound around at least one long side surface 31, the lower surface 32, and the other long side surface 31 of the electrode body 30, and is at most twice as wide as the depth of the battery case 50. It is the length obtained by adding L51. Therefore, specifically, it is preferable that “L33 × 2 + 2π × L35R / 2” ≦ “L40” ≦ “depth of battery case 50 × 2 + L51”. This range includes "L33 x 2 + H30" and "L32R x 2 + H30".

The maximum width W40 has a length longer than half the circumference of the circumference of the opening 53. Preferably, the first and second ends 43A, 43B are arranged so that the first and second ends 43A, 43B arranged on one short side surface of the battery case 50 do not form a gap between them. Is a length that overlaps with a predetermined width. Further, it is preferable that the first end portion 43A and the second end portion 43B do not reach the long side surface 51 facing the short side surface 54. Therefore, roughly, it is preferable that “W51 + L51 / 2 × 2” ≦ “W40” ≦ “W51 + L51 × 2”. More specifically, it is preferable that “W52 + 2π × R1 / 4 × 2 + L52 / 2 × 2” ≦ “W40” ≦ “W52 + 2π × R1 / 4 × 4 + L52 × 2”.

The wide surface 42 has a length L43 in the row direction and a width W42 in the width direction. For example, the length L43 is set to "L33" ≤ "L43" ≤ "depth of the battery case 50". Further, for example, the width W42 is set to “W30” ≦ “W42” ≦ “W51”.

The folded surface 46 has a length L44 in the row direction and a width W42 in the width direction. For example, the length L44 is set to "H30" ≤ "L44" ≤ "L51".
The lower end portion 44 has a length L44 in the row direction and a width W43 in the width direction.

The first and second end portions 43A and 43B have a width W43 in the width direction. For example, the width W43 is set to "(W40-W42) / 2". Further, in the first and second end portions 43A and 43B, the side adjacent to the wide surface 42 has a length L43 or less in the row direction, and the side adjacent to the wide surface 42 has a length L43. , The length of the opposite side of the adjacent side is less than the length L43. That is, it has a tapered shape in the width direction. More specifically, the first and second end portions 43A and 43B have a trapezoidal shape in which only the inclined sides 43C and 43D on the lower end portion 44 side are not orthogonal to the other sides. For example, in the first end portion 43A adjacent to one of the wide surfaces 42, the inclined side 43C is inclined in the direction of the one wide surface 42 by an inclination angle θ1 with respect to the extension line of the bending line 47. Further, for example, in the second end portion 43B of the other wide surface 42, the inclined side 43D is inclined in the direction of the other wide surface 42 by an inclination angle θ2 with respect to the extension line of the bending line 47. In the present embodiment, the inclination angle θ1 and the inclination angle θ2 are different angles, and the magnitude relationship of the angles is “θ1 <θ2”.

The operation of the secondary battery of the present embodiment will be described with reference to FIGS. 4 and 5.
As shown in FIG. 4, when the production of the secondary battery 10 is started, the film processing process (step S10), the winding process (step S11), and the insertion process (step S12) are performed.

In the film processing process, the resin film 40 is cut out from the long film.
In the wrapping process, each wide surface 42 of the cut-out resin film 40 is fixed to each long side surface 31 of the electrode body 30 with an adhesive or the like, and the resin film 40 is previously wound around the electrode body 30. At this time, the first and second end portions 43A and 43B protruding from the long side surface 31 of the electrode body 30 and the lower end portion 44 protruding from the lower surface 32 of the electrode body 30 are not fixed.

In the insertion process, the lower surface 32 of the electrode body 30 is made to face the opening 53 of the battery case 50, and the electrode body 30 is inserted into the battery case 50 through the opening 53 with the lower surface 32 first. Then, the inserted electrode body 30 is inserted into the battery case 50 when the lid 20 fixed to the electrode body 30 comes into contact with the opening 53 of the battery case 50. The insertion of the electrode body 30 into the battery case 50 is completed before the lower surface 32 of the electrode body 30 comes into contact with the bottom surface 52 of the battery case 50. After that, the opening 53 of the battery case 50 and the lid 20 are welded to seal the battery case 50.

The insertion process will be described in detail with reference to FIG.
In the stage before the insertion process is performed, the resin film 40 is maintained in a shape folded in half so as to sandwich the long side surface 31 of the electrode body 30, for example, the shape shown in FIG. At this time, the width W42 of the wide surface 42 is less than the width W51 of the long side surface 51 of the battery case 50, preferably less than the width W52. Since the maximum width W40 of the resin film 40 is wider than the width W51 of the long side surface 51 of the battery case 50, the lower end portions 44, the first and second end portions 43A, 43B of the resin film 40 are the battery case 50. It extends to a length exceeding the short side surface 54. Therefore, corresponding to the insertion of the electrode body 30 into the battery case 50, the surface of the lower end portion 44 hits the opening 53, while the first and second end portions 43A and 43B have the inclined sides 43C and 43D. Will hit the opening 53 of the battery case 50.

Here, in the insertion process, a step of bending the lower end portion 44 and the first and second end portions 43A and 43B against the opening 53 will be described. At this time, the electrode body 30 and the resin film 40 are moved by aligning the width center of the electrode body 30, the width center of the resin film 40, and the width center of the battery case 50 and moving them along the width center. Insert it into the battery case 50.

As shown in FIG. 5, when the insertion process of step S12 is started, the lower end bending step (step S20), the first end bending step (step S21), the second end bending step (step S22), and , The end overlapping step (step S23) is sequentially performed. In general, in the insertion process, first, the lower end 44 of the resin film 40 is bent in the lower end bending step, then the first end 43A is bent in the first end bending step, and then the first end 43A is bent. , The second end 43B is bent in the second end bending step. Finally, in the end overlapping step, the bent first and second end portions 43A and 43B and the lower end portion 44 are overlapped.

In the lower end bending step, the lower end portion 44 of the resin film 40 is brought into contact with the side of the short side surface 54 of the opening 53 of the battery case 50 and bent in the direction opposite to the insertion direction, that is, the electrode body 30. This is a step of bending so as to approach the end face 34. More specifically, the lower end 44 of the resin film 40 extending beyond the side of the short side 54 of the opening 53 comes into line contact with the opening 53 as the electrode body 30 is inserted into the battery case 50. The line contact position moves toward the tip of the lower end 44, and is bent toward the end face 34. The lower end 44 of the resin film 40 is bent, for example, with the bending line 41 as a folding line. Further, since the lower end portion 44 is composed of two strip pieces having a length L45 in the row direction due to the notch 45 having in the center in the row direction, the cut portions (strip pieces) are overlapped or opened. The curvature of the folded surface 46 is absorbed. That is, the notch 45 of the lower end portion 44 reduces the drag force against the force from the bending line 41 to the lower end portion 44. As a result, the stress applied to the lower end portion 44 and the folded surface 46 is suppressed.

In the first end bending step, the first end 43A of the resin film 40 is brought into contact with the corner 56 and the short side surface 54 of the opening 53 of the battery case 50 in the direction of the end face 34 of the electrode body 30. This is the process of bending. That is, the first end portion 43A of the resin film 40 extending beyond the side of the short side surface 54 of the opening portion 53 has each inclined side 43C facing the opening portion 53. At this time, each inclined side 43C has an inclination angle θ1 rather than being parallel to the side of the opening 53. Each inclined side 43C makes point contact with the opening 53, and the contact point moves from the wide surface 42 side to the tip in the width direction in response to the electrode body 30 being inserted into the battery case 50. I will go. As a result, the first end portion 43A is guided along the opening 53 via the contact point. As the electrode body 30 enters the battery case 50, the first end portion 43A opens the opening 53 from one corner portion 56 to the short side surface 54 while the point contact position of the inclined side 43C moves toward the tip end. , And even move along the other corner 55.

More specifically, the inclined side 43C has its tip side retracted with respect to the opening 53 based on the inclined angle θ1. Therefore, when the electrode body 30 enters the battery case 50, the inclined side 43C enters the opening 53 along the long side surface 51, comes into contact with the corner portion 56 from the long side surface 51 side, and then becomes the corner portion 56. The point contact position moves from the long side surface 51 side to the short side surface 54 side along the corner portion 56 which is an arc having a radius of curvature R1. Then, the extending direction of the inclined side 43C is changed from the direction along the long side surface 51 to the direction along the short side surface 54. That is, the stretching direction of the first end portion 43A changes from the direction along the long side surface 51 to the direction along the short side surface 54. At this time, the bending line 41 between the wide surface 42 and the first end portion 43A is bent as a folding line.

By the way, since the inclination angle θ1 of the inclined side 43C is smaller than the inclination angle θ2 of the inclined side 43D, the amount of retreat with respect to the opening 53 in the insertion direction is smaller than the amount of retreat of the inclined side 43D, and is ahead of the inclined side 43D. Contact the opening 53. Therefore, the first end 43A is bent along the opening 53 before the second end 43B.

In the second end bending step, the second end 43B of the resin film 40 is brought into contact with the corner 55 and the short side surface 54 of the opening 53 of the battery case 50 in the direction of the end face 34 of the electrode body 30. This is the process of bending. That is, the second end 43B of the resin film 40 extending beyond the side of the short side surface 54 of the opening 53 has each inclined side 43D facing the opening 53. At this time, each inclined side 43D is not parallel to the side of the opening 53 and has an inclination angle θ2. Each inclined side 43D makes point contact with the opening 53, and the contact point moves from the wide surface 42 side to the tip in the width direction in response to the electrode body 30 being inserted into the battery case 50. I will go. As a result, the second end portion 43B is guided along the opening 53 via the contact point. As the electrode body 30 enters the battery case 50, the second end portion 43B opens the opening 53 from one corner portion 55 to the short side surface 54 while the point contact position of the inclined side 43D moves toward the tip end. , And further move along the other corner 56.

More specifically, the inclined side 43D has its tip side retracted with respect to the opening 53 based on the inclined angle θ2. Therefore, when the electrode body 30 enters the battery case 50, the inclined side 43D enters the opening 53 along the long side surface 51, comes into contact with the corner portion 55 from the long side surface 51 side, and then becomes the corner portion 55. The point contact position moves from the long side surface 51 side to the short side surface 54 side along the corner portion 55 which is an arc having a radius of curvature R1. Then, the extending direction of the inclined side 43D is changed from the direction along the long side surface 51 to the direction along the short side surface 54. That is, the stretching direction of the second end portion 43B changes from the direction along the long side surface 51 to the direction along the short side surface 54. At this time, the bending line 41 between the wide surface 42 and the second end portion 43B is bent as a folding line.

By the way, since the inclination angle θ2 of the inclined side 43D is larger than the inclination angle θ1 of the inclined side 43C, the amount of retreat with respect to the opening 53 in the insertion direction is larger than the retreat amount of the inclined side 43C and after the inclined side 43C. Contact the opening 53. Therefore, the second end 43B is bent along the opening 53 after the first end 43A. That is, the second end portion 43B is later overlapped with the first end portion 43A that has been bent first. At this time, by first contacting the side of the first end portion 43A with the tip of the inclined side 43D instead of the side of the second end portion 43B, the first end portion 43A is not pressed against the side of the first end portion 43A. The second end 43B slides on the outside or inside of the end 43A and overlaps. That is, the first end portion 43A guided to the inclined side 43C and the second end portion 43B guided to the inclined side 43D are shifted from each other in the timing of extending the short side surface 54, so that the first end portion 43A Since the end of the inclined side 43D hits the side of the wall and there is a difference in the speed at which the short side surface 54 is stretched, they are likely to overlap each other.

On the other hand, assuming that the two inclination angles θ1 and θ2 are the same, the tips of the first and second end portions 43A and 43B extend the short side surface 54 at the same timing, and the same is true at the center of the short side surface 54. Since they face each other in such a state, the first and second end portions 43A and 43B that hit each other may come into contact with each other and float up. On the other hand, according to the present embodiment, since the first and second end portions 43A and 43B overlap each other, the resin film 40 is preferably arranged between the electrode body 30 and the battery case 50. Become.

The end overlapping step is a step of superimposing the bent lower end portion 44, the first end portion 43A, and the second end portion 43B on each other. When the electrode body 30 is inserted into the battery case 50, the lower end portion 44 is bent, then the first end portion 43A is bent so as to overlap the lower end portion 44, and finally, the second end portion 43B is the first end. It bends so as to overlap the portion 43A and the lower end portion 44. When the lower end portion 44 enters the battery case 50 by the width W43 thereof, the bending and overlapping are completed. The first end portion 43A and the second end portion 43B are completely bent when their inclined sides 43C and 43D enter the battery case 50, and when they further enter the battery case 50, they remain in the form of bending. The first end portion 43A and the second end portion 43B of the above are overlapped.

When the inclination angles θ1 and θ2 are less than 45 °, the height of the tip when the inclined sides 43C and 43D are bent is lower than the height (= width W43) when the lower end portion 44 is bent. .. Therefore, the space partitioned by the inclined side 43C and the lower end portion 44, the space partitioned by the inclined side 43D and the lower end portion 44 is covered by the lower end portion 44, and the first end portion 43A and the second end portion 43B. Will be. The overlapping order of the lower end portion 44, the first end portion 43A, and the second end portion 43B is not limited to the above.

As a result, the resin film 40 is suitably arranged between the electrode body 30 and the battery case 50.
As described above, according to the secondary battery and the method for manufacturing the secondary battery of the present embodiment, the effects described below can be obtained.

(1) It is not necessary to process the resin film 40 by heat welding or the like before inserting the electrode body 30 into the battery case 50 to form a bag shape. By inserting the resin film 40 not formed into a bag shape into the battery case 50 together with the electrode body 30, the ends of the resin film 40 are guided to the inner wall surface 57 of the battery case 50 by the inclination angles θ1 and θ2. The bent resin film 40 is arranged between the electrode body 30 and the battery case 50. As a result, the resin film 40 is not heat-welded, so that through holes are generated at the heat-welded parts, burrs that cause cracks are generated, and the resin film 40 is heat-welded due to stress caused by distortion of the bag shape or the like. There is no risk of crevices at the restraint points. Therefore, the insulating property of the resin film 40 is preferably maintained between the electrode body 30 and the battery case 50.

(2) When the electrode body 30 is inserted into the battery case 50, the timings at which the first and second end portions 43A and 43B are bent along the inner wall surface 57 of the battery case 50 are different. Therefore, even if the first and second end portions 43A and 43B face each other, the bent states are different, so that the first and second end portions 43A and 43B can be suitably overlapped without colliding with each other. The sex is enhanced.

(3) Since the inclination angle θ1 of each inclined side 43C of the first end portion 43A and the inclination angle θ2 of each inclined side 43D of the second end portion 43B are the same angle, the resin film 40 can be easily processed.
(4) Since the width of the lower end portion 44 adjacent to the folded surface 46 is the same as the length L44 of the folded surface 46, interference with the battery case 50 and interference with other ends is reduced, and the battery case 50 is reduced. Easy to place in.

(5) If the lower end portion 44 does not have a notch 45 and the folded surface 46 is curved, it becomes difficult to bend the lower end 44 adjacent to the folded surface 46 in the direction of the folded surface 46. In this regard, according to the present embodiment, since the lower end portion 44 has one or a plurality of notches 45 orthogonal to the row direction, even if the folded surface 46 is curved in the row direction, such a curvature is formed in the notches 45. By creating an angle between them and absorbing it, the end can be bent in the direction of the folded surface.

(6) The resin film 40 can be made to have insulating property and chemical resistance.
(7) A resin film 40 can be arranged between the electrode body 30 of the lithium ion secondary battery and the battery case 50.

(8) By winding the resin film 40 around the electrode body 30 in advance, the resin film 40 can be easily arranged between the battery case 50 and the electrode body 30.
(Other embodiments)
The above embodiment can also be implemented in the following embodiments.

-In the above embodiment, the case where the electrode body 30 is wound with the positive electrode plate and the negative electrode plate sandwiching the separator is illustrated, but the present invention is not limited to this, and a plurality of positive electrodes are formed if they have a flat shape. A plate and a plurality of negative electrode plates may be laminated with a separator in between.

In the above embodiment, in the winding process, each wide surface 42 of the cut out resin film 40 is fixed to each long side surface 31 of the electrode body 30 with an adhesive or the like, and is pre-wound around the electrode body 30. The case was illustrated. However, the present invention is not limited to this, and the winding process may be omitted. At this time, the resin film may be arranged so as to be sandwiched between the electrode body and the battery case in response to the insertion of the electrode body into the battery case in the insertion process. At this time, the adhesive may be arranged on the lower surface or the long side surface of the electrode body, may be arranged on the folded surface and the wide surface of the resin film, or may be arranged on both.

-In the above embodiment, the case where the secondary battery 10 is a lithium ion secondary battery has been illustrated, but the secondary battery is not limited to this, and the secondary battery is an alkaline secondary battery such as a nickel hydrogen secondary battery or a nickel cadmium secondary battery. It may be a battery.

The resin film 40 may be composed of any one of PP, PPE, and PE, or may be composed of a combination of at least two of these PP, PPE, and PE.

In the above embodiment, the case where the lower end portion 44 has a notch 45 has been illustrated, but the present invention is not limited to this, and the lower end portion has a notch if the folded surface of the resin film can be made into a rectangular flat surface. You don't have to.

In the above embodiment, the case where the lower end portion 44 has the same length L44 as the folded surface 46 with respect to the winding direction R has been illustrated, but the present invention is not limited to this, and the length of the lower end portion is larger than the length of the folded surface. May be long or short.

For example, even if the shape expands from the folded surface, the expanding tip can be arranged in the battery case because it is bent along the corners. On the contrary, even if the shape is narrowed from the folded surface, if the portion covered by the first end portion and the second end portion is narrowed, the interference at the time of overlapping can be reduced.

In the above embodiment, the angles of the inclined sides 43C on both sides of one wide surface 42 are the same inclination angle θ1, and the angles of the inclined sides 43D on both sides of the other wide surface 42 are the same inclination angle θ2. An example is given for a certain case. However, the present invention is not limited to this, and the inclined sides on both sides of one wide surface may be different, or the inclined sides on both sides of the other wide surface may be different. Even if the angles of the left and right inclined sides of the wide surface are different, the end portion can be bent following the opening if there is an inclined side.

-In the above embodiment, the case where the inclination angles θ1 and θ2 of the inclination sides 43C and 43D are different is illustrated. However, not limited to this, if it is possible to adjust so that when two ends abut, one end can ride on the other end, the inclination angles θ1 and θ2 are the same. There may be.

-In the above embodiment, the case where the radii of curvature R1 and R2 of the corners 55 and 56 are the same has been illustrated. However, the present invention is not limited to this, and the radius of curvature R1 of the corner portion 55 and the radius of curvature R2 of the corner portion 56 may be different.

As shown in FIG. 6, the radius of curvature R1 of the corners 55 at both ends of one long side surface 51 and the radius of curvature R2 of the corners 56 at both ends of the other long side surface 51 may be different. At this time, the inclination angles θ1 and θ2 may be different or the same. For convenience of explanation, it is assumed that R1 radius of curvature <radius of curvature R2 and the inclination angles θ1 and θ2 are the same. At this time, for example, if the radius of curvature R1 <the radius of curvature R2, the arc length is "the arc of R1 <the arc of R2". On the other hand, since the width relationship is "W51> W52> W53" and the length relationship is "L51> L52> L53", the center of the long side surface 51 (W51 / 2) to the center of the short side surface 54 ( The distance to L51 / 2) is shorter via the corner 56 than via the corner 55. Therefore, there is a difference in speed and angle when the first end portion 43A guided to the corner portion 56 and the second end portion 43B guided to the corner portion 55 move along the short side surface 54. As a result, the first end portion 43A and the second end portion 43B abut at an angle, and are likely to overlap each other due to differences in speed when moving on the short side surface 54 or the like.

At the two corners 55 and 56 of the opening 53 of the battery case 50, the timing at which the first and second ends 43A and 43B of the resin film 40 bend along the roundness is different, so that the ends are different from each other. Even if they face each other, since the bent states are different, the possibility that the ends do not collide with each other and are suitably overlapped with each other is increased.

-Also, the diagonals of the corners may have the same curvature, and the curvatures of the adjacent corners may be different.
-Also, three or more types of curvatures may be applied to the four corners.
-In this way, when the two corner portions 55 and 56 at both ends of the short side surface 54 have different curvatures, the timing at which each end surface moves along the short side surface changes due to the difference in curvature. Become. Therefore, in such a configuration, the inclination angles may be different or may be the same. In any case, even if the ends face each other, the bent state is different, so that there is a high possibility that the ends do not collide with each other and are preferably overlapped with each other.

In the above embodiment, the two corner portions 55 and 56 on both ends of the short side surface 54, which is the side of the opening 53 and faces the first end portion 43A and the second end portion 43B, have the same rounded curvature. Although a certain case has been illustrated, the inclination angles may be different, and the curvatures of the two corners at both ends of the short side may be different.

-In the above embodiment, the case where the secondary battery is used as a power source for an automobile has been illustrated. However, the present invention is not limited to this, and the secondary battery may be used as a power source other than the automobile such as various moving bodies and fixed bodies as long as it is used as a power source.

10 ... Secondary battery, 20 ... Lid body, 21 ... External terminal, 30 ... Electrode body, 31 ... Long side surface, 32 ... Bottom surface, 33 ... Top surface, 34 ... End face, 40 ... Resin film, 41 ... Bending wire, 42 ... Wide surface, 43A ... 1st end, 43B ... 2nd end, 43C ... Inclined side, 43D ... Inclined side, 44 ... Lower end, 45 ... Notch, 46 ... Folded surface, 47 ... Bending line, 50 ... Battery Case, 51 ... long side surface, 52 ... bottom surface, 53 ... opening, 54 ... short side surface, 55 ... corner part, 56 ... corner part, 57 ... inner wall surface, 400 ... battery film, 401 ... fixed part, 402 ... melting Holes, 403 ... cracks, 442 ... long sides, 443 ... short sides.

Claims (9)

A secondary battery in which a film is placed between the electrode body and the battery case.
The battery case has rounded corners of a rectangular opening into which the electrode body is inserted.
The film is made of resin, and is arranged in a row with a first surface facing one of two opposing side surfaces of the battery case and a second surface facing the first surface. However, the folded surface provided between the first surface and the second surface is parallel to the row direction and is adjacent to both sides of the first surface, the second surface, and the folded surface, respectively. It has an end portion that extends to a position that extends beyond the width of the battery case.
The end portion adjacent to the first surface is the first end portion, and the first end portion is from the end point of the boundary line between the first surface and the folded surface to the extension line of the boundary line. It has an inclined side having an inclination angle in the direction of the first surface,
The end portion adjacent to the second surface is the second end portion, and the second end portion is from the end point of the boundary line between the second surface and the folded surface to the extension line of the boundary line. It has an inclined side having an inclination angle in the direction of the second surface,
A secondary battery having an angle different from the inclination angle of the inclined side of the first end portion and the inclination angle of the inclined side of the second end portion. A secondary battery in which a film is placed between the electrode body and the battery case.
The battery case has rounded corners of a rectangular opening into which the electrode body is inserted.
The film is made of resin, and is arranged in a row with a first surface facing one of two opposing side surfaces of the battery case and a second surface facing the first surface. However, the folded surface provided between the first surface and the second surface is parallel to the row direction and is adjacent to both sides of the first surface, the second surface, and the folded surface, respectively. It has an end portion that extends to a position that extends beyond the width of the battery case.
The end portion adjacent to the first surface is the first end portion, and the first end portion is from the end point of the boundary line between the first surface and the folded surface to the extension line of the boundary line. It has an inclined side having an inclination angle in the direction of the first surface,
The end portion adjacent to the second surface is the second end portion, and the second end portion is from the end point of the boundary line between the second surface and the folded surface to the extension line of the boundary line. It has an inclined side having an inclination angle in the direction of the second surface,
A secondary battery in which the two corners on both ends of the side of the opening where the first end and the second end face each other have different rounded curvatures. The inclination angles of the inclined sides of the first end on both sides of the first surface are the same.
The secondary battery according to claim 1 or 2, wherein the inclination angles of the inclined sides of the second end portions on both sides of the second surface are the same. The secondary battery according to any one of claims 1 to 3, wherein the end portion adjacent to the folded surface has a side on an extension line of the boundary line. The secondary battery according to any one of claims 1 to 4, wherein the end portion adjacent to the folded surface has one or a plurality of notches extending in a direction orthogonal to the row direction. The resin is any one of polypropylene (PP), polyphenylene ether (PPE) and polyethylene (PE), or a combination of at least two of PP, PPE and PE. Any one of claims 1 to 5. The secondary battery described in item 1. The secondary battery according to any one of claims 1 to 6, wherein the secondary battery is a lithium ion secondary battery. A method for manufacturing a secondary battery in which a film is arranged between the electrode body and the battery case.
The battery case has rounded corners of a rectangular opening into which the electrode body is inserted, and the film is made of resin and is formed on one of two opposing side surfaces of the battery case. A first surface facing each other, a second surface facing the first surface, a folded surface provided between the first surface and the second surface arranged in a row, and the above-mentioned Ends provided adjacent to both sides of the first surface, the second surface, and the folded surface in parallel with the row direction, and extend to a position protruding from the width of the battery case. The end portion adjacent to the first surface is the first end portion, and the first end portion is the end point of the boundary line between the first surface and the folded surface. The end portion having an inclined side having an inclination angle in the direction of the first surface with respect to the boundary line and adjacent to the second surface is the second end portion, and the second end portion is the second end portion. It has an inclined side having an inclination angle in the direction of the second surface with respect to the boundary line from the end point of the boundary line between the surface and the folded surface.
A step of arranging the film between the opening of the battery case and the electrode body,
By inserting the electrode body into the opening of the battery case while facing the tip surface of the electrode body and the folded surface of the film, the first end portion and the second end portion of the film are different from each other. The process of bending along the roundness at the timing,
A method for manufacturing a secondary battery, comprising a step of arranging the film between the electrode body and the battery case by inserting the electrode body into the opening of the battery case. The method for manufacturing a secondary battery according to claim 8, wherein in the step of arranging the film, the film is wound around the electrode body in advance.

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