JP7369351B2 - Secondary batteries and secondary battery manufacturing methods - Google Patents

Description

The present disclosure relates to a secondary battery and a method for manufacturing a secondary battery.

Patent Document 1 discloses a stacked secondary battery including a stacked body in which positive electrodes and negative electrodes are alternately stacked. By configuring the structure so that no pressing force is applied to the edges of the positive electrode and the edges of the negative electrode, burr protrusions are generated on the cut surfaces of the positive and negative electrodes during the formation process (cutting process) of the positive and negative electrodes. It is stated that even in such cases, short-circuiting between the positive electrode and the negative electrode can be suppressed due to the burr protrusion.

Patent Document 2 discloses an all-solid-state battery that includes a negative electrode layer, a negative active material layer, a solid electrolyte layer, a positive active material layer, and a positive electrode layer as one unit. This all-solid-state battery has a structure in which an insulating member is disposed between each layer in order to prevent short circuits due to breakage of the outer peripheral edge of the battery, electrode burrs, etc.

JP2011-222388A Japanese Patent Application Publication No. 2014-130754

The configurations described in Patent Document 1 and Patent Document 2 have a problem because short circuits caused by burrs on the positive electrode plate and the negative electrode plate cannot be sufficiently suppressed.

The present disclosure aims to provide a secondary battery in which short circuits are suppressed, and also to provide a method for manufacturing such a secondary battery.

A secondary battery of the present disclosure is a secondary battery including an electrode laminate in which a positive electrode plate having a positive electrode current collector and a negative electrode plate having a negative electrode current collector are laminated with a separator interposed therebetween, The positive electrode current collector has a burr that protrudes toward one side in the thickness direction on at least a portion of the peripheral edge, and the negative electrode current collector has a burr that protrudes toward one side in the thickness direction on at least a portion of the peripheral edge. The positive electrode plate and the negative electrode plate have a burr protruding toward one side of the positive electrode plate, and the positive electrode plate and the negative electrode plate have a protruding direction of the burr on the positive electrode current collector and a burr on the negative electrode current collector in the same direction, and The circumferential edge of the current collector and the circumferential edge of the negative electrode current collector are stacked such that at least a portion of the circumferential edge overlaps in the stacking direction.

The method for manufacturing a secondary battery of the present disclosure includes manufacturing a secondary battery including an electrode stack in which a positive electrode plate having a positive electrode current collector and a negative electrode plate having a negative electrode current collector are laminated with a separator interposed therebetween. A method comprising: punching out a base material in which a positive electrode active material is applied to a positive electrode metal foil, which is a material of the positive electrode current collector, to obtain the positive electrode plate; and a negative electrode, which is a material of the positive electrode current collector. The step of punching out the base material coated with the negative electrode active material on the metal foil for use in the negative electrode to obtain the negative electrode plate, and the step of punching out the positive electrode plate and the punching direction of the negative electrode plate in the same direction, and The method includes the step of stacking the positive electrode plate and the negative electrode plate in such a manner that at least a portion of the peripheral edge of the electric body and the peripheral edge of the negative electrode current collector overlap in the stacking direction.

According to the present disclosure, it is possible to provide a secondary battery in which short circuits are suppressed. Furthermore, a method for manufacturing such a secondary battery can be provided.

FIG. 1 is a perspective view of a secondary battery in one embodiment. FIG. 3 is a plan view showing a positive electrode plate and a negative electrode plate, with the exterior body and separator omitted. 3 is a cross-sectional view corresponding to the III-III cross section in FIG. 2. FIG. 3 is a cross-sectional view corresponding to the IV-IV cross section in FIG. 2. FIG. It is an explanatory view for explaining a process of obtaining a positive electrode plate. It is an explanatory view for explaining the process of laminating a positive electrode plate and a negative electrode plate. FIG. 3 is an explanatory diagram for explaining a process of welding a positive electrode tab portion to a positive electrode terminal.

<Embodiment 1>
As shown in FIG. 1, the secondary battery 10 is configured by, for example, a lithium ion battery, and includes a rectangular flexible exterior body 12 and an electrode stack 17 sealed within the exterior body 12. and an electrolytic solution (not shown), and a positive electrode terminal 14 and a negative electrode terminal 15 exposed from the exterior body 12. The exterior body 12 is formed by welding the peripheral edges of a pair of rectangular flexible laminate films made of, for example, aluminum.

As shown in FIGS. 2 and 3, the electrode laminate 17 has a rectangular positive electrode plate 20 and a rectangular negative electrode plate 30, which is one size larger than the positive electrode plate 20, alternately repeating mountain folds and valley folds. It is formed by alternately stacking a plurality of separators 40 in the form of belts that are folded in between. In this case, the positive electrode plates 20 are sandwiched between opposing surfaces on one side of the separator 40, and the negative electrode plates 30 are sandwiched between opposing surfaces on the other side.

The separator 40 is made of, for example, an insulating synthetic resin nonwoven fabric. A rectangular plate-shaped portion between two adjacent folds in the separator 40 is one size larger than the negative electrode plate 30. That is, as shown in FIG. 3, when comparing the sizes of the positive electrode plate 20, the negative electrode plate 30, and the separator 40 in the secondary battery 10, the separator 40 is the largest and the positive electrode plate 20 is the smallest.

As shown in FIG. 4, the positive electrode plate 20 includes a positive electrode current collector 21 and a positive electrode active material 25 coated on both surfaces of the positive electrode current collector 21. The positive electrode current collector 21 is made of a conductive material such as aluminum foil (metal foil for positive electrode) 21A having a thickness of 10 μm to 20 μm. The positive electrode active material 25 is made of a material capable of intercalating and deintercalating positive ions, such as lithium ions.

The positive electrode current collector 21 has a burr 23 on at least a portion of the peripheral edge 22 that protrudes toward one side in the thickness direction. The burr 23 is formed to extend along the direction in which the aluminum foil 21A is punched out in the step of obtaining the positive electrode plate 20, which will be described later. The burr 23 is formed along the peripheral edge 22 due to the ductility of the aluminum foil 21A, and has, for example, a sawtooth shape that tapers toward the tip. The positive electrode current collector 21 has a so-called rounded surface on the edge opposite to the burr 23 in the thickness direction. In other words, the burr 23 is configured to protrude toward one side of the positive electrode current collector 21 in the thickness direction, but not to the other side.

As shown in FIG. 2, the positive electrode current collector 21 has a substantially rectangular plate shape, and a rectangular plate-shaped positive electrode tab portion (positive electrode current collecting portion) 27 protrudes from the end of one side in the longitudinal direction. It is formed like this. That is, the positive electrode tab portion 27 is integrally formed with the positive electrode current collector 21 and protrudes to be exposed from the separator 40 . Each positive electrode tab portion 27 is electrically connected to the positive electrode terminal 14 . The positive electrode active material 25 is not applied to the positive electrode tab portion 27 .

The positive electrode tab portion 27 has a cutout portion 28 that is a portion of the peripheral edge 22 of the positive electrode current collector 21 . The notch portion 28 is formed so that the positive electrode plate 20 is asymmetrical with respect to a center line CL that bisects the positive electrode plate 20. The center line CL is a line passing through the middle of two opposing sides of the positive electrode current collector 21 having a substantially rectangular plate shape, and extends linearly along the protruding direction of the positive electrode tab portion 27. The notch portion 28 has a slit shape extending along the protruding direction of the positive electrode tab portion 27 and is provided in the positive electrode tab portion 27 . In the direction in which the center line CL extends, the length of the notch portion 28 is longer than the lengths of a first welded portion 29A and a second welded portion 29B, which will be described later. The cutout portion 28 is provided offset in the direction away from the centerline CL, leaving spaces for forming the first welded portion 29A and the second welded portion 29B on both sides of the centerline CL.

The plurality of positive electrode plates 20 are welded to the positive electrode terminal 14 on both sides of the notch portion 28 with the plurality of positive electrode tab portions 27 bundled in the stacking direction. In other words, the positive electrode tab portion 27 has a first welded portion 29A and a second welded portion 29B welded to the positive electrode terminal 14 on both sides of the notch portion 28. The first welding part 29A and the second welding part 29B physically fix the positive electrode current collector 21 and the positive electrode terminal 14 and electrically connect them. In this embodiment, the plurality of positive electrode plates 20 are connected to the positive electrode terminal 14 via the plurality of welding parts 29A and 29B, thereby providing a configuration suitable for increasing the output of the secondary battery 10.

As shown in FIG. 4, the negative electrode plate 30 includes a negative electrode current collector 31 and a negative electrode active material 35 coated on both surfaces of the negative electrode current collector 31. The negative electrode current collector 31 is made of a conductive material such as copper foil (metal foil for negative electrode) with a thickness of 10 μm to 20 μm, for example. The negative electrode active material 35 is made of a material capable of inserting and releasing cations such as lithium ions.

The negative electrode current collector 31 has a burr 33 on at least a portion of the peripheral edge 32 that protrudes toward one side in the thickness direction. The burr 33 is formed to extend along the direction in which the copper foil is punched out in the process of obtaining the negative electrode plate 30, which will be described later. The burr 33 is formed along the peripheral edge 32 due to the ductility of the copper foil, and has, for example, a sawtooth shape that tapers toward the tip. Copper foil has greater ductility than aluminum foil 21A, and the protruding height of burr 33 tends to be larger than the protruding height of burr 23. The negative electrode current collector 31 has a so-called rounded surface on the edge opposite to the burr 33 in the thickness direction. In other words, the burr 33 is configured to protrude toward one side of the negative electrode current collector 31 in the thickness direction, but not to the other side.

As shown in FIG. 2, the negative electrode current collector 31 has a substantially rectangular plate shape, and a rectangular plate-shaped negative electrode tab portion (negative electrode current collecting portion) 37 protrudes from the end of one side in the longitudinal direction. It is formed like this. That is, the negative electrode tab portion 37 is integrally formed with the negative electrode current collector 31 and protrudes to be exposed from the separator 40. Each negative electrode tab portion 37 is electrically connected to the negative electrode terminal 15. The negative electrode active material 35 is not applied to the negative electrode tab portion 37 .

The negative electrode tab portion 37 has a cutout portion 38 that is a part of the peripheral edge 32 of the negative electrode current collector 31 . The notch portion 38 is formed so that the negative electrode plate 30 is asymmetrical with respect to a center line CL that bisects the negative electrode plate 30. The center line CL is a line that passes through the middle of two opposing sides of the negative electrode current collector 31 having a substantially rectangular plate shape, and extends linearly along the protruding direction of the negative electrode tab portion 37. The cutout portion 38 has a slit shape extending along the protruding direction of the negative electrode tab portion 37 and is provided in the negative electrode tab portion 37 . In the direction in which the center line CL extends, the length of the notch portion 38 is longer than the lengths of a first welded portion 39A and a second welded portion 39B, which will be described later. The cutout portion 38 is provided offset in the direction away from the centerline CL, leaving spaces for forming the first welded portion 39A and the second welded portion 39B on both sides of the centerline CL.

The plurality of negative electrode plates 30 are welded to the negative electrode terminal 15 on both sides of the notch portion 38 in a state in which the plurality of negative electrode tab portions 37 are bundled in the stacking direction. In other words, the negative electrode tab portion 37 has a first welded portion 39A and a second welded portion 39B welded to the negative electrode terminal 15 on both sides of the notch portion 38. The first welding part 39A and the second welding part 39B physically fix the negative electrode current collector 31 and the negative electrode terminal 15 and electrically connect them. In this embodiment, the plurality of negative electrode plates 30 are connected to the negative electrode terminal 15 via the plurality of welded parts 39A and 39B, thereby providing a configuration suitable for increasing the output of the secondary battery 10.

The positive electrode plate 20 and the negative electrode plate 30 are stacked such that at least a portion of the peripheral edge 22 of the positive electrode current collector 21 and the peripheral edge 32 of the negative electrode current collector 31 overlap in the stacking direction. As shown in FIG. 2, as shown in FIG. An example may be a configuration in which the peripheral edge 22 of 21 and the peripheral edge 32 of the negative electrode current collector 31 are arranged to intersect with each other. The positive electrode plate 20 and the negative electrode plate 30 are configured such that the positive electrode tab portion 27 and the negative electrode tab portion 37 protrude in mutually opposite directions, so that the peripheral edge 22 and the peripheral edge 32 are arranged to intersect with each other when viewed from the stacking direction. has. Further, even when the positive electrode plate 20 and the negative electrode plate 30 are arranged so that the peripheral edge 22 of the positive electrode plate 20 is inclined with respect to the peripheral edge 32 of the negative electrode plate 30 when viewed from the stacking direction, the positive electrode plate 20 and the negative electrode plate 30 are arranged at an angle according to the inclination angle. The peripheral edge 22 and the peripheral edge 32 may be arranged to intersect with each other when viewed from the stacking direction. In addition, as a form in which at least a portion of the peripheral edge 22 of the positive electrode current collector 21 and the peripheral edge 32 of the negative electrode current collector 31 overlap in the stacking direction, the peripheral edge 22 of the positive electrode current collector 21 and the negative electrode A configuration may be adopted in which a part of the peripheral edge 32 of the current collector 31 extends in parallel to a direction perpendicular to the stacking direction.

As shown in FIG. 4, the positive electrode plate 20 and the negative electrode plate 30 are stacked with the protruding direction of the burrs 23 of the positive electrode current collector 21 and the protruding direction of the burrs 33 of the negative electrode current collector 31 in the same direction. In FIG. 4, the first portion 41 of the separator 40, the positive electrode plate 20, the second portion 42 of the separator 40, the negative electrode plate 30, and the third portion 43 of the separator 40 are stacked in this order from above. The burr 23 of the positive electrode current collector 21 protrudes downward in FIG. 4 and partially invades the second portion 42 of the separator 40. The burr 33 of the negative electrode current collector 31 protrudes downward in FIG. 4 and partially invades the third portion 43 of the separator 40. In other words, only one of the burrs 23 of the positive electrode current collector 21 and the burrs 33 of the negative electrode current collector 31 is invaginated in the portions 41, 42, and 43 of the separator 40 that are interposed between the positive electrode plate 20 and the negative electrode plate 30. , the other does not invaginate. In the positive electrode plate 20 and the negative electrode plate 30, burrs 23 and 33 are formed from both the front and back sides of the separator 40 at a position where the peripheral edge 22 of the positive electrode current collector 21 and the peripheral edge 32 of the negative electrode current collector 31 overlap in the stacking direction. The configuration is such that it cannot be accessed. The thickness of the separator 40 is not particularly limited; It is preferable that it is thicker than the maximum protrusion amount in 33. According to such a configuration, short-circuiting of the secondary battery 10 due to the burrs 23 of the positive electrode current collector 21 and the burrs 33 of the negative electrode current collector 31 can be further suppressed.

Next, a method for manufacturing the secondary battery 10 will be explained. The method for manufacturing the secondary battery 10 includes the steps of obtaining a positive electrode plate 20, a step of obtaining a negative electrode plate 30, a step of stacking the positive electrode plate 20 and the negative electrode plate 30, and a step of welding the positive electrode tab portion 27 to the positive electrode terminal 14. and a step of welding the negative electrode tab portion 37 to the negative electrode terminal 15. The method for manufacturing the secondary battery 10 may include any other steps, but includes a step of removing burrs 23 from the positive electrode current collector 21 and a step of removing burrs 33 from the negative electrode current collector 31. You don't have to be there. Since the method for manufacturing the secondary battery 10 does not include the step of removing such burrs 23 and 33, it can contribute to reducing the number of steps.

In the step of obtaining the positive electrode plate 20, the positive electrode plate 20 is obtained by punching out the base material 20A in which the positive electrode active material 25 is applied to the aluminum foil 21A. The step of obtaining the positive electrode plate 20 can be performed using, for example, a press machine having a punching blade having the same external shape as the positive electrode plate 20. As shown in FIG. 5, the base material 20A is formed by applying positive electrode active material 25 on both sides of a strip-shaped aluminum foil 21A at predetermined intervals. In the step of obtaining the positive electrode plate 20, the positive electrode plate 20 is formed by punching the base material 20A by applying a punching blade across the area where the positive electrode active material 25 is applied and the area where the positive electrode active material 25 is not applied. In this process, a burr 23 is formed on at least a portion of the peripheral edge 22 of the positive electrode current collector 21, protruding along the punching direction. The direction in which the positive electrode plate 20 is punched can be defined as the direction from the position where the punching blade first hits the positive electrode plate 20 to the position where the punching blade leaves.

In the step of obtaining the negative electrode plate 30, the negative electrode plate 30 is obtained by punching out a base material in which the negative electrode active material 35 is applied to copper foil. The step of obtaining the negative electrode plate 30 can be performed using, for example, a press machine having a punching blade having the same external shape as the negative electrode plate 30. The base material is formed by applying negative electrode active material 35 on both sides of a strip-shaped copper foil at predetermined intervals. In the step of obtaining the negative electrode plate 30, the negative electrode plate 30 is formed by punching by applying a punching blade across the area where the negative electrode active material 35 is applied and the area where the negative electrode active material 35 is not applied in the base material. In this process, a burr 33 that protrudes along the punching direction is formed on at least a portion of the peripheral edge 32 of the negative electrode current collector 31 . The direction in which the negative electrode plate 30 is punched can be defined as the direction from the position where the punching blade first hits the negative electrode plate 30 to the position where the punching blade leaves.

In the step of stacking the positive electrode plate 20 and the negative electrode plate 30, the direction in which the positive electrode plate 20 is punched and the direction in which the negative electrode plate 30 is punched out are the same direction, and the peripheral edge 22 of the positive electrode current collector 21 and the negative electrode current collector The positive electrode plate 20 and the negative electrode plate 30 are stacked such that at least a portion of the peripheral edge 32 of the electrode plate 31 overlaps in the stacking direction. In other words, in the step of stacking the positive electrode plate 20 and the negative electrode plate 30, the side to which the punching blade was applied in the step of obtaining the positive electrode plate 20 and the side to which the punching blade was applied in the step of obtaining the negative electrode plate 30 The surface opposite to the surface of the negative electrode plate 30 on the side faces each other with the separator 40 interposed therebetween, and at least one of the peripheral edge 22 of the positive electrode current collector 21 and the peripheral edge 32 of the negative electrode current collector 31 The positive electrode plate 20 and the negative electrode plate 30 are stacked so that their parts overlap. As shown in FIG. 6, in the step of laminating the positive electrode plate 20 and the negative electrode plate 30, the positive electrode plate 20 and the negative electrode plate 30 are laminated alternately, and the separator 40 is folded in a zigzag manner, so that the A separator 40 is interposed. At this time, it can be confirmed that the positive electrode plate 20 and the negative electrode plate 30 are not reversed from their normal orientations, using the positions of the notches 28 and 38 of the positive electrode plate 20 and the negative electrode plate 30 as a guide. The normal orientation of the positive electrode plate 20 and the negative electrode plate 30 is such that the direction in which the positive electrode plate 20 is punched and the direction in which the negative electrode plate 30 is punched out are the same direction. This is an orientation in which the protruding direction and the protruding direction of the burr 33 of the negative electrode current collector 31 are the same direction.

In the step of welding the positive electrode tab portions 27 to the positive electrode terminal 14, the plurality of positive electrode tab portions 27 are welded to the positive electrode terminal 14 on both sides of the notch portion 28 while being bundled in the stacking direction. As shown in FIG. 6, first, the horn 50 to which ultrasonic vibrations have been applied is pressed against a portion of the plurality of positive electrode tab portions 27 located on one side of the notch portion 28 to form the first weld portion 29A. Next, the horn 50 to which ultrasonic vibration has been applied is pressed against a portion of the plurality of positive electrode tab portions 27 located on the other side of the notch portion 28 to form a second weld portion 29B. At this time, since the notch 28 is interposed between the first welded part 29A and the second welded part 29B, ultrasonic vibrations and heat when forming the second welded part 29B are transferred to the first welded part 29A. It has become difficult to Before forming the first welded portion 29A, a positioning pin may be inserted into the cutout portion 28 to align the positions of the plurality of positive electrode tab portions 27 with each other. For example, if one positive electrode plate 20 among the plurality of positive electrode plates 20 is reversed from its normal orientation, the positive electrode tab portion 27 of the reversed positive electrode plate 20 may interfere with the positioning pin, causing the plurality of positive electrode plates 20 to Before welding the portion 27, it is possible to easily detect whether the positive electrode plate 20 is turned over.

In the step of welding the negative electrode tab portions 37 to the negative electrode terminal 15, the plurality of negative electrode tab portions 37 are welded to the negative electrode terminal 15 on both sides of the notch portion 38 while being bundled in the stacking direction. Specifically, first, the horn 50 to which ultrasonic vibration has been applied is pressed against a portion of the plurality of negative electrode tab portions 37 located on one side of the notch portion 38 to form the first weld portion 39A. Next, the horn 50 to which ultrasonic vibration has been applied is pressed against a portion of the plurality of negative electrode tab portions 37 located on the other side of the notch portion 38 to form a second weld portion 39B. At this time, since the notch 38 is interposed between the first welded part 39A and the second welded part 39B, ultrasonic vibrations and heat when forming the second welded part 39B are transferred to the first welded part 39A. It has become difficult to Before forming the first welding portion 39A, a positioning pin may be inserted into the cutout portion 38 to align the positions of the plurality of negative electrode tab portions 37 with each other. For example, if one negative electrode plate 30 among the plurality of negative electrode plates 30 is reversed from its normal orientation, the negative electrode tab portion 37 of the reversed negative electrode plate 30 may interfere with the positioning pin, causing the plurality of negative electrode plates 30 to Before welding the portion 37, the reversal of the negative electrode plate 30 can be easily detected.

According to the embodiment described above, the following effects are exhibited. For example, when the protruding direction of the burrs on the positive electrode current collector and the protruding direction of the burrs on the negative electrode current collector are in directions toward each other at a portion where the peripheral edge of the positive electrode current collector and the negative electrode current collector overlap in the stacking direction, There is a possibility that the burrs on the positive electrode current collector and the burrs on the negative electrode current collector penetrate the separator and come into contact with each other. On the other hand, in the secondary battery 10 of the present embodiment, since the protruding direction of the burrs 23 of the positive electrode current collector 21 and the protruding direction of the burrs 33 of the negative electrode current collector 31 are the same, It is possible to suppress the burrs 23 and 33 from coming into contact with each other at a portion where the peripheral edge 22 and the peripheral edge 32 of the negative electrode current collector 31 overlap in the stacking direction. Therefore, it is possible to provide the secondary battery 10 in which short circuits are suppressed. Moreover, a method for manufacturing such a secondary battery 10 can be provided.

In this embodiment, both the positive electrode plate 20 and the negative electrode plate 30 have notches 28 and 38 that are partially cut out from their peripheral edges so as to be asymmetrical with respect to the center line CL that bisects the positive electrode plate 20 and the negative electrode plate 30. . Generally, the burrs 23 and 33 are of such a size that it is difficult to visually recognize them, so it is difficult to determine their protruding direction visually or with a sensor. In the configuration in which the positive electrode plate 20 has the notch portion 28, it can be easily determined whether the positive electrode plate 20 is reversed from its normal orientation using the position of the notch portion 28 in the positive electrode plate 20 as a guide. In the configuration in which the negative electrode plate 30 has the notch portion 38, it is possible to easily determine whether the negative electrode plate 30 is reversed from its normal orientation using the position of the notch portion 38 in the negative electrode plate 30 as a guide. As a result, the protruding direction of the burrs 23 of the positive electrode current collector 21 and the protruding direction of the burrs 33 of the negative electrode current collector 31 can be reliably made to be the same direction.

In the present embodiment, the positive electrode plate 20 has a configuration in which the positive electrode active material 25 is coated on both sides of a plate-shaped positive electrode current collector 21, and the positive electrode tab on which the positive electrode active material 25 is not applied in the positive electrode current collector 21. A section 27 is provided. A notch portion 28 is provided in the positive electrode tab portion 27 . The plurality of positive electrode plates 20 are welded to the positive electrode terminal 14 on both sides of the notch portion 28 with the plurality of positive electrode tab portions 27 bundled in the stacking direction. According to this configuration, the notch 28 interposed between the first welded part 29A and the second welded part 29B is used to determine whether or not the positive electrode plate 20 is reversed from its normal orientation. be able to. As a result, the protruding direction of the burr 23 of the positive electrode current collector 21 can be reliably set in a predetermined direction.

In this embodiment, the negative electrode plate 30 has a configuration in which a negative electrode active material 35 is applied to both sides of a plate-shaped negative electrode current collector 31, and negative electrode tabs on which the negative electrode active material 35 is not applied in the negative electrode current collector 31. A section 37 is provided. The negative electrode tab portion 37 is provided with a notch portion 38 . The plurality of negative electrode plates 30 are welded to the negative electrode terminal 15 on both sides of the notch portion 38 in a state in which the plurality of negative electrode tab portions 37 are bundled in the stacking direction. According to this configuration, the notch 38 interposed between the first welding part 39A and the second welding part 39B is used to determine whether or not the negative electrode plate 30 is reversed from its normal orientation. be able to. As a result, the protruding direction of the burr 33 of the negative electrode current collector 31 can be reliably set in a predetermined direction.

<Other embodiments>
The above embodiment can be modified and implemented as follows. Further, the above embodiment and the following modification examples can be implemented in combination with each other within a technically consistent range.

In the above embodiment, a configuration is illustrated in which both the positive electrode plate and the negative electrode plate each have a notch, but the present invention is not limited to this. For example, even in a configuration in which at least one of the positive electrode plate and the negative electrode plate has a notch, the above-described effect of regulating front and back reversal can be achieved. Moreover, the positive electrode plate and the negative electrode plate do not need to have a notch. In addition, the shape and arrangement of the notch portion can be changed as appropriate.

The separator does not necessarily need to be made of nonwoven fabric. That is, the separator may be made of, for example, a stretched film.

The positive electrode active material may be applied only to one side of the positive electrode current collector. The negative electrode current collector may be coated with the negative electrode active material only on one side.

The secondary battery may be a secondary battery other than a lithium ion battery.

The present disclosure may be implemented in the following embodiments.
In the secondary battery of the present disclosure, at least one of the positive electrode plate and the negative electrode plate has a notch portion in which a portion of the peripheral edge is cut out so as to be asymmetrical with respect to a center line that bisects the positive electrode plate and the negative electrode plate. You may.

In the secondary battery of the present disclosure, the positive electrode plate has a configuration in which a positive electrode active material is applied to at least one surface of a plate-shaped positive electrode current collector, and the positive electrode active material is applied to the positive electrode current collector. A positive electrode current collecting section is provided, the positive electrode current collecting section is provided with the notch, and the plurality of positive electrode plates are formed by bundling the plurality of positive electrode current collecting sections in a stacking direction. In this state, the positive electrode terminal may be welded to both sides of the notch.

In the secondary battery of the present disclosure, the negative electrode plate has a configuration in which a negative electrode active material is applied to at least one surface of a plate-shaped negative electrode current collector, and the negative electrode active material is applied to the negative electrode current collector. The negative electrode current collector is provided with a negative electrode current collector, the negative electrode current collector is provided with the cutout, and the plurality of negative electrode plates are formed by bundling the plurality of negative electrode current collectors in a stacking direction. In this state, the negative electrode terminal may be welded to both sides of the notch.

The foregoing examples are for illustrative purposes only and are not to be construed as limiting the invention. Although the invention has been described in terms of exemplary embodiments, the language used in describing and illustrating the invention is to be understood to be in a descriptive and illustrative rather than a restrictive sense. Changes may be made in the form as detailed herein without departing from the scope or spirit of the invention and within the scope of the appended claims. Although reference has been made herein to specific structures, materials and embodiments in the detailed description of the invention, it is not intended to limit the invention to the disclosure herein; rather, the invention is defined by the appended claims. It shall cover all functionally equivalent structures, methods and uses within the scope.

10... Secondary battery 17... Electrode laminate 20... Positive electrode plate 20A... Base material 21... Positive electrode current collector 21A... Aluminum foil (metal foil for positive electrode)
22... Peripheral edge 23... Burr 30... Negative electrode plate 31... Negative electrode current collector 32... Peripheral edge 33... Burr 40... Separator

Claims (2)

A secondary battery comprising an electrode laminate in which a positive electrode plate having a positive electrode current collector and a negative electrode plate having a negative electrode current collector are laminated with a separator interposed therebetween,
The positive electrode current collector has a burr protruding toward one side in the thickness direction on at least a portion of the peripheral edge,
The negative electrode current collector has a burr protruding toward one side in the thickness direction on at least a part of the peripheral edge,
The positive electrode plate and the negative electrode plate have the protruding direction of the burrs on the positive electrode current collector and the protruding direction of the burrs on the negative electrode current collector in the same direction, and the peripheral edge of the positive electrode current collector and the negative electrode current collector. are laminated in such a manner that at least a portion of their peripheral edges overlap in the lamination direction,
A positive electrode current collector portion is formed on the positive electrode current collector and projects so as to be exposed from the separator,
The positive electrode current collector is provided with a slit-shaped notch extending along the protruding direction of the positive electrode current collector,
The notch portion of the positive electrode current collector is formed so that the positive electrode plate is asymmetrical with respect to a center line that extends along the protruding direction of the positive electrode current collector and bisects the positive electrode plate. and
A negative electrode current collector part is formed on the negative electrode current collector and projects so as to be exposed from the separator,
The negative electrode current collector is provided with a slit-shaped notch extending along the protruding direction of the negative electrode current collector,
The cutout portion of the negative electrode current collector is formed so that the negative electrode plate is asymmetrical with respect to a center line that extends along the protruding direction of the negative electrode current collector and bisects the negative electrode plate. A secondary battery characterized by : A method for manufacturing a secondary battery comprising an electrode laminate in which a positive electrode plate having a positive electrode current collector and a negative electrode plate having a negative electrode current collector are laminated with a separator interposed therebetween, the method comprising:
A positive electrode current collector portion is formed on the positive electrode current collector and projects so as to be exposed from the separator,
The positive electrode current collector is provided with a slit-shaped notch extending along the protruding direction of the positive electrode current collector,
The notch portion of the positive electrode current collector is formed so that the positive electrode plate is asymmetrical with respect to a center line that extends along the protruding direction of the positive electrode current collector and bisects the positive electrode plate. and
A negative electrode current collector part is formed on the negative electrode current collector and projects so as to be exposed from the separator,
The negative electrode current collector is provided with a slit-shaped notch extending along the protruding direction of the negative electrode current collector,
The cutout portion of the negative electrode current collector is formed so that the negative electrode plate is asymmetrical with respect to a center line that extends along the protruding direction of the negative electrode current collector and bisects the negative electrode plate. and
punching out a base material in which a positive electrode active material is applied to a positive electrode metal foil, which is a material of the positive electrode current collector, to obtain the positive electrode plate;
a step of punching out a base material in which a negative electrode active material is applied to a negative electrode metal foil, which is a material of the negative electrode current collector, to obtain the negative electrode plate;
The direction in which the positive electrode plate is punched and the direction in which the negative electrode plate is punched are the same direction, and at least a portion of the peripheral edge of the positive electrode current collector and the peripheral edge of the negative electrode current collector overlap in the stacking direction. A method for manufacturing a secondary battery, comprising: stacking the positive electrode plate and the negative electrode plate in a form.

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