JP7103853B2 - Laminated electrode plate group, secondary battery, and manufacturing method of secondary battery - Google Patents

Description

The present invention relates to a laminated electrode plate group of a secondary battery, a secondary battery having the electrode plate group, and a method for manufacturing the secondary battery.

Lithium-ion secondary batteries, which are one of the non-aqueous electrolyte secondary batteries, have high energy density and high capacity, and are therefore used as power sources for driving electric vehicles (EVs) and hybrid vehicles (HVs). Has been done. A lithium ion secondary battery has a group of electrode plates in which a positive electrode plate and a negative electrode plate having electrode mixture layers provided on both sides of an electrode core body are wound or laminated via a separator. Aluminum alloy foil or copper foil for secondary battery electrodes is used for the electrode core. A current collector plate connected to an external electrode terminal is connected to a lead portion made of an electrode core body at the edge portion of the electrode plate (see, for example, Patent Document 1).

For example, in the secondary battery described in Patent Document 1, at least one electrode plate of the strip-shaped positive / negative electrode plate is projected from the edge portion of the other electrode plate, and is wound or laminated via a separator. Laser welding is performed between the protruding edge of the power generation element (electrode plate group) and the current collector.

Japanese Unexamined Patent Publication No. 10-106536

In the electrode plate group in which the positive electrode plate and the negative electrode plate are wound so as to sandwich the separator, the positive electrode plate and the negative electrode plate are fixed with a relatively strong binding force, so that the relative positions of the positive electrode plate and the negative electrode plate are displaced. The risk of occurrence is small.

On the other hand, the electrode plate group in which the positive electrode plate and the negative electrode plate are laminated so as to sandwich the separator is merely stacked with the positive electrode plate, the negative electrode plate, and the separator having almost no binding force. Therefore, until the positive electrode plate and the negative electrode plate are welded to the current collector, the positions between the electrode plates may deviate from the positions when they are laminated due to an external force such as vibration during manufacturing.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a laminated electrode plate group capable of suppressing the occurrence of misalignment between electrode plates during manufacturing, and the electrode plate group. It is an object of the present invention to provide a secondary battery having a secondary battery and a method for manufacturing the secondary battery.

The laminated electrode plate group that solves the above problems is a laminated electrode plate group that is a group of electrode plates in which a positive electrode plate and a negative electrode plate are laminated with a separator interposed therebetween, and is a terminal portion of the electrode plate group. The terminal portion in which only the edge portion of the positive electrode plate is arranged or only the edge portion of the negative electrode plate is arranged in the laminated direction, and the terminal portion provided in the terminal portion. It is a foil collecting part to which the current collecting part extending in the direction along the part is connected, and the end edge part arranged in the terminal part is gathered in the laminated direction, and the gathered edge is gathered. It is provided with the foil collecting portion to which the portions are joined.

The secondary battery for solving the above problems is a secondary battery having a group of electrode plates in which a positive electrode plate and a negative electrode plate are laminated with a separator sandwiched between them, and the electrode plate group is from the laminated electrode plate group described above. Therefore, at least a part of the foil collecting portion of the electrode plate group and the current collecting portion connected to the external terminal is welded.

The method for manufacturing a secondary battery that solves the above problems is a method for manufacturing a secondary battery having a group of electrode plates in which a positive electrode plate and a negative electrode plate are laminated with a separator sandwiched between them, and is a terminal portion of the electrode plate group. Then, in the direction in which the terminal portions in which only the positive electrode plates are arranged or the edge portions of the terminal portions in which only the edge portions of the negative electrode plates are arranged are laminated in the laminated direction. An edge collecting step, a foil collecting portion forming step of joining a plurality of collected terminal portions to form a foil collecting portion, a contacting step of bringing the current collecting portion into contact with the foil collecting portion, and the above. A welding step of welding a portion of contact between the foil collecting portion and the current collecting portion, and a housing step of accommodating the electrode plate group in which the current collecting portion is welded to the foil collecting portion in the case of the secondary battery. To be equipped with.

Misalignment of the electrode plates of the laminated electrode plate group in which the positive electrode plate, the separator, the negative electrode plate, and the separator are stacked in this order may deteriorate the battery characteristics. One of the causes of such misalignment is that an external force such as vibration is applied after stacking during manufacturing. In this regard, according to such a configuration or method, in the laminated electrode plate group, the edge portions are joined to form the foil collecting portion before the current collecting portion is fixed, so that the positive electrode is formed. Since the plates or the negative electrode plates are connected to each other, it is possible to suppress the occurrence of misalignment between the electrode plates constituting the electrode plate group at the time of manufacturing.

Further, since the edge portion of each electrode plate is a metal thin film having low rigidity, unintended deformation is likely to occur, but by using the foil collecting portion, the rigidity is increased and unintended deformation is suppressed. Further, by increasing the rigidity, it becomes easy to connect the foil collecting portion and the current collecting portion.

Further, where it is preferable that the current collectors are connected to all the edge portions, since all the edge portions are joined as foil collectors in advance, it is possible to connect the current collector portions to the edge portions. It is easy, and the conductivity between each electrode plate and the current collector is ensured.

As a preferred configuration, the terminal portion has a base end portion which is an end portion close to the external terminal in the longitudinal direction and a tip portion which is an end portion distant from the external terminal, and the foil collecting portion is the foil collecting portion. It is provided at least in a part between the base end portion and a position close to the base end portion by a predetermined length from the tip end.

As a preferred method, in the foil collecting portion forming step, a base end portion which is an end portion close to the upper side of the case and a tip end portion which is an end portion close to the lower side of the case with respect to the longitudinal direction of the terminal portion are predetermined. The foil collecting portion is formed at least in a portion between the position close to the base end portion and the length of the foil collecting portion.

According to such a configuration or method, at least a part between the base end portion of the terminal portion of the electrode plate group and the position close to the base end portion by a predetermined length from the tip is closed by the foil collecting portion. However, on the contrary, the portion where the foil collecting portion is not provided is open. By opening the tip side of the terminal portion, the electrolytic solution can be easily supplied to the electrode plate group from the opened tip side. In particular, by providing the tip side so as to be the lower side on which the electrolytic solution stays, the permeability of the electrolytic solution to the electrode plate group having the foil collecting portion can be maintained in a high state.

As a preferred configuration, in the foil collecting portion, the two end edges facing each other in the laminated direction are interfacially joined to each other.
According to such a configuration, since the metal foil is joined without changing the shape of the edge portion, the breakage of the metal foil is suppressed. That is, it is possible to reduce the possibility that the foil shape cannot be maintained by forming a spherical shape that gathers the surroundings due to melting, or that the thickness of the foil becomes uneven and easily breaks. Reliability is improved.

As a preferred configuration, in the electrode plate group, the edge portion of one of the terminal portions is made of an aluminum alloy foil, and the edge portion of the other terminal portion is made of a copper foil.
According to such a configuration, in the lithium ion secondary battery, it is possible to suppress the occurrence of misalignment between the electrode plates constituting the electrode plate group at the time of manufacturing.

As a preferred configuration, in the foil collecting portion, the protruding portion of the terminal portion is trimmed at a predetermined position in the protruding direction, and the predetermined position is all the said in the laminated direction. This is the position where the terminals are stacked.

As a preferred method, prior to the accommodating step, the projecting portion of the terminal portion is at a predetermined position in the projecting direction, and the predetermined position where all the terminal portions are laminated with respect to the stacking direction. It is provided with a cutting process for trimming.

According to such a configuration or method, it is possible to reduce the size of the secondary battery and increase the capacity of the secondary battery by making the protruding length of the foil collecting portion the minimum necessary length.
As a preferred configuration, the foil collecting portion is sandwiched between the slits provided in the current collecting portion from the laminated direction.

As a preferred configuration, the current collecting portion has a slit that sandwiches the foil collecting portion in the laminated direction, and at least a part of the foil collecting portion sandwiched between the slits is welded to the current collecting portion. There is.

As a preferred method, in the foil collecting portion forming step, the two edge portions facing each other in the laminated direction are interfacially joined to each other, and in the contacting step, the foil collecting portion is connected to the current collecting portion in the longitudinal direction. The current collecting portion is brought into contact with the foil collecting portion by being sandwiched between the slits extending in the welding step, and in the welding step, at least a part of the foil collecting portion is touched along the slit of the current collecting portion. Weld the current collector.

According to such a configuration or method, the foil collecting portion can be sandwiched between the slits of the current collecting portion, so that the conductivity between the current collecting portion and the foil collecting portion can be ensured. Further, the foil collecting portion has a higher rigidity than a single terminal portion because each terminal portion is assembled. Therefore, the foil collecting portion can be sandwiched between the current collecting portions, and the current collecting portion can be easily attached to the foil collecting portion. Further, since the foil collecting portion has a large heat capacity, it becomes easy to control the energy applied for welding. Therefore, for example, in laser welding, it is possible to suppress the possibility that the laser penetrates the foil collecting portion.

The secondary battery that solves the above-mentioned problems is a secondary battery having a plurality of electrode plate groups in which a positive electrode plate and a negative electrode plate are laminated with a separator interposed therebetween, and the electrode plate group is the laminated electrode plate described above. It is composed of a group, and at least a part of a foil collecting portion of the plurality of electrode plates and a current collecting portion connected to an external terminal is welded to each other.

As a preferred method, a electrode plate group laminating step of laminating a plurality of the electrode plate groups is provided prior to the abutting step, and in the abutting step, each foil collecting portion of the plurality of the electrode plate groups is combined with the current collecting unit. The current collecting portion is brought into contact with the foil collecting portion by sandwiching it in each of a plurality of slits extending in the longitudinal direction of the above.

According to such a configuration or method, a foil collecting portion of a plurality of electrode plates is welded to the current collecting portion. Therefore, it is easy to construct a secondary battery having a plurality of electrode plate groups.

According to the present invention, it is possible to suppress the occurrence of misalignment between the plates during manufacturing.

The schematic diagram which shows the structure of the 1st Embodiment of a secondary battery. The schematic diagram which shows the cross-sectional structure of the electrode plate group of the same embodiment. The schematic diagram which shows the structure of the electrode plate group and the current collector plate of the same embodiment. Top view showing a lead portion in the same embodiment. Top view showing a lead portion in the same embodiment. The flowchart which shows the procedure of assembling the secondary battery in the same embodiment. The schematic diagram which shows the structure of the electrode plate group about the 2nd Embodiment of a secondary battery. The front view which shows the structure of the current collector plate in the same embodiment. The flowchart which shows the procedure of assembling the secondary battery in the same embodiment. The schematic diagram which shows the structure of the other embodiment of a secondary battery.

(First Embodiment)
A first embodiment of a laminated electrode plate group, a secondary battery, and a method for manufacturing a secondary battery will be described with reference to FIGS. 1 to 6. In the present embodiment, the secondary battery is a lithium ion secondary battery.

A plurality of secondary batteries 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 is a sealed battery having a rectangular cuboid shape.

As shown in FIG. 1, the secondary battery 10 includes a rectangular battery case 11 having an opening on the upper side, a lid 12 for sealing the battery case 11, and an electrode body housed inside the battery case 11. 20 and the liquid non-aqueous electrolyte 27 injected into the battery case 11 are provided. The battery case 11 and the lid 12 are made of a metal such as an aluminum alloy. The secondary battery 10 is formed by attaching a lid 12 to the battery case 11 to form a sealed battery case. Further, the secondary battery 10 is provided with two external terminals 13 used for charging and discharging electric power on the lid body 12.

The electrode plate group 20 is formed by alternately laminating the positive electrode plate 21 and the negative electrode plate 22 in the laminating direction (the direction perpendicular to the paper surface in FIG. 1) with the separator 23 sandwiched between them. In the present embodiment, the electrode plate group 20 constitutes a laminated electrode plate group by laminating the positive electrode plate 21, the negative electrode plate 22, and the separator 23 while maintaining their respective flat surfaces. The electrode plate group 20 has a positive electrode lead portion 214 as a terminal portion in which the positive electrode plate 21 protrudes from one end side in the longitudinal direction (left side in FIG. 1) and a negative electrode on the other end side (right side in FIG. 1) in the same longitudinal direction. The plate 22 has a lead portion 224 of the negative electrode as a terminal portion protruding from the plate 22. In the lead portion 214 of the positive electrode, the tip portion 211C (see FIG. 2) as the edge portion of the positive electrode plate 21 is assembled in the stacking direction at the portion where only the positive electrode plate 21 is arranged in the longitudinal direction of the electrode plate group 20. ing. Further, in the lead portion 214 of the positive electrode, a current collecting plate 14 as a current collecting portion connected to the external terminal 13 is welded to the foil collecting portion 30 which is an aggregated portion along the lateral direction of the electrode plate group 20. Has been done. In the lead portion 224 of the negative electrode, the tip portion 221C (see FIG. 2) as the edge portion of the negative electrode plate 22 is assembled in the stacking direction at the portion where only the negative electrode plate 22 is arranged in the longitudinal direction of the electrode plate group 20. ing. Further, in the lead portion 224 of the negative electrode, a current collector plate 14 connected to the external terminal 13 is welded to the foil collecting portion 30 which is an aggregated portion along the lateral direction of the electrode plate group 20.

The separator 23 is a non-woven fabric made of polypropylene or the like for holding the non-aqueous electrolyte 27 between the positive electrode plate 21 and the negative electrode plate 22. Further, as the separator 23, a porous polymer film such as a porous polyethylene film, a porous polyolefin film, and a porous polyvinyl chloride film, or a lithium ion or ion conductive polymer electrolyte film is used alone or in combination. You can also do it.

(Non-aqueous electrolyte)
The non-aqueous electrolyte 27 is a composition in which a supporting salt is contained in a non-aqueous solvent. Here, as the non-aqueous solvent, one or two selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and the like. More than seed materials can be used. As supporting salts, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiI One or more lithium compounds (lithium salts) selected from the above can be used.

(Positive plate)
With reference to FIG. 2, in the positive electrode plate 21, the positive electrode mixture 212 and 213 are formed on the first surface 211A and the second surface 211B of the positive electrode base material 211 as the aluminum alloy foil for the secondary battery positive electrode, which is the electrode core, respectively. It has been applied. The positive electrode base material 211 of the positive electrode plate 21 is a thin film (foil) made of an aluminum alloy as a conductive material made of a metal having good conductivity. The portion of the positive electrode plate 21 where the positive electrode mixture 212 and 213 are not applied is referred to as the tip portion 211C.

The positive electrode mixture 212 and 213 have a positive electrode active material. The positive electrode active material may additionally contain one or more elements in addition to the transition metal element (ie, at least one of Ni, Co, and Mn). Additional elements include Group 1 (alkali metals such as sodium), Group 2 (alkaline earth metals such as magnesium and calcium), Group 4 (transition metals such as titanium and zirconium), and Group 6 (chromium) in the periodic table. , A transition metal such as tungsten), and any element belonging to Group 8 (transition metal such as iron) can be contained. Further, the additional element may include any element belonging to Group 13 (metalloid element such as boron or aluminum) and Group 17 (halogen such as fluorine) in the periodic table. can. Preferably, the positive electrode active material is "LiNiComnO ₂ -based positive electrode active material". The "LiNiCoMnO ₂ -based positive electrode active material" means a composite oxide containing Li, Ni, Co, and Mn, and may further contain a metal element different from Li, Ni, Co, and Mn.

Further, the positive electrode mixture 212 and 213 may contain a conductive material. As the conductive material, for example, carbon black such as acetylene black (AB) and Ketjen black, and graphite (graphite) can be used.

For the positive electrode plate 21, for example, the positive electrode active material, the conductive material, the solvent, and the binder are kneaded, and after the kneading, the electrode slurry generated by containing the positive electrode mixture 212 is used as the positive electrode base material 211. It is produced by applying to and drying. Here, as the solvent, for example, an NMP (N-methyl-2-pyrrolidone) solution can be used. Further, as the binder, for example, polyvinylidene fluoride (PVdF), styrene butadiene rubber (SBR), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC) and the like can be used. In the present embodiment, the electrode slurry is adjusted so that the proportion of solid matter is 40% or more and 70% or less.

(Negative electrode plate)
Next, in the negative electrode plate 22, the negative electrode mixture 222 and 223 are applied to the first surface 221A and the second surface 221B of the negative electrode base material 221 as the current collecting foil which is the electrode core, respectively. As the negative electrode base material 221 of the negative electrode plate 22, the same components as those of the conventional secondary battery can be used. For example, as the material of the base material, a conductive material made of a metal having good conductivity is preferably used. For example, as the negative electrode base material 221, a thin film (foil) made of copper, nickel, or an alloy thereof can be used. The portion of the negative electrode plate 22 to which the negative electrode mixture 222 and 223 has not been applied is referred to as the tip portion 221C.

The negative electrode mixture 222 and 223 has a negative electrode active material. The negative electrode active material is a material capable of occluding and releasing lithium, and for example, a powdered carbon material made of graphite or the like can be used. Then, in the negative electrode plate 22, the negative electrode active material, the solvent, and the binder are kneaded in the same manner as in the positive electrode plate 21, and the electrode slurry generated by containing the negative electrode mixture 222 after kneading is applied to the negative electrode base material 221. It is produced by drying. In this embodiment, the binder comprises carboxymethyl cellulose (CMC) having sodium salts.

(Current collector plate)
As shown in FIG. 3, the lid 12 is provided with an external terminal 13 of the positive electrode and an external terminal 13 of the negative electrode on the outer surface side, and the current collector plate 14 of the positive electrode and the current collector plate 14 of the negative electrode are provided on the inner surface side. Is provided. Since the positive electrode current collector plate 14 and the negative electrode current collector plate 14 have the same structure, the positive electrode current collector plate 14 will be described in detail here, and the description of the negative electrode current collector plate 14 will be omitted. do.

The current collector plate 14 of the positive electrode is a plate-shaped member made of a conductor, and is orthogonal to the fixing portion 14D (see FIG. 1) fixed to the inner surface of the lid 12 and the fixing portion 14D (see FIG. 1). It is provided with an extension portion 140 extending in the direction of the extension. The fixing portion 14D (see FIG. 1) is mechanically fixed to the lid 12 by a conductor penetrating the lid 12, and is electrically and mechanically connected and fixed to the external terminal 13.

The extension portion 140 extends from the fixing portion 14D fixed to the lid 12 toward the bottom surface of the battery case 11. The extension portion 140 has a length for arranging the tip 14A at a position before reaching the bottom surface of the battery case 11. In other words, the extension portion 140 is arranged at a position where the tip 14A thereof is separated upward from the bottom surface of the battery case 11 by a predetermined distance.

The surface of the extension portion 140 is oriented in a direction orthogonal to the longitudinal direction of the electrode plate group 20. As a result, when the extension portion 140 is connected to the electrode plate group 20, the length required in the longitudinal direction of the electrode plate group 20 may be about the thickness of the extension portion 140. This makes it possible to reduce the size of the secondary battery 10 or increase the capacity of the secondary battery 10.

The extension portion 140 has a slit 141 extending in the longitudinal direction, which is a direction from the tip 14A toward the fixing portion 14D. Further, the slit 141 penetrates the current collector plate 14 in the thickness direction of the current collector plate 14. The extension portion 140 has a first extension piece 142 and a second extension piece 143 separated by the slit 141 on both sides of the slit 141.

The extension portion 140 has a slit 141 opened at the tip 14A and an end point of the slit 141 at the base end portion 14C on the fixed portion side. That is, when viewed from the fixed portion 14D side, the slit 141 is between the first extension piece 142 and the second extension piece 143, which are branched at the base end portion 14C and arranged substantially parallel to the tip 14A. It is provided. The first extension piece 142 and the second extension piece 143 have a tapered shape at the tip 14A, and the tip 14A is widened so as to widen the width of the slit 141. The extension portion 140 has a sandwiching portion 14B following the tip 14A in the longitudinal direction. The width of the slit 141 is narrow in the sandwiching portion 14B, and the foil collecting portion 30 of the lead portion 214 of the positive electrode sandwiched in the slit 141 is pressed between the first extending piece 142 and the second extending piece 143. By doing so, it can be restrained. Further, the extension portion 140 has a base end portion 14C on the fixed portion side of the sandwiching portion 14B. The width of the slit 141 of the base end portion 14C is wider than that of the sandwiching portion 14B, and the lead portion 214 of the positive electrode is not pressed between the first extension piece 142 and the second extension piece 143. , Arranged in an unrestrained state.

(Foil collection part)
With reference to FIGS. 2 to 4, the foil collecting portion 30 formed from the lead portion 214 of the positive electrode, the lead portion 224 of the negative electrode, and the lead portion 214 of the positive electrode and the lead portion 224 of the negative electrode will be described. Since the lead portion 214 of the positive electrode and the lead portion 224 of the negative electrode have the same structure, the lead portion 214 of the positive electrode will be described in detail, and the lead portion 224 of the negative electrode will be omitted.

As shown in FIG. 2, the lead portion 214 of the positive electrode is the tip portion 211C of the positive electrode base material 211, and is configured between the position P1 and the position P3 of the end portion of the separator 23. More specifically, in the electrode plate group 20, the positive electrode plate 21, the negative electrode plate 22 and the separator 23 are laminated from the center of the electrode plate group 20 in the longitudinal direction to the substantially position P3, and the positive electrode plate group 20 is the positive electrode from the position P3 to the position P2. The plate 21 and the separator 23 are laminated, and only the positive electrode plate 21 is laminated between the position P2 and the position P1. Further, the positive electrode mixture 212 and 213 of the positive electrode plate 21 are provided between the center of the electrode plate group 20 in the longitudinal direction and the substantially position P3. Therefore, the tip portion 211C of the positive electrode plate 21 between the vicinity of the position P3 and the position P1 is composed of only the positive electrode base material 211.

As shown in FIG. 3, the lead portion 214 of the positive electrode has a longitudinal direction in the lateral direction of the electrode plate group 20, and a lateral direction in which the lead portion 214 protrudes from the electrode plate group 20 along the longitudinal direction of the electrode plate group 20. The direction.

The lead portion 214 of the positive electrode has an upper end portion 214a on the upper side, a lower end portion 214b on the lower side, and a central portion 214c between the upper end portion 214a and the lower end portion 214b in the longitudinal direction thereof.

FIG. 4 shows the upper surface of the electrode plate group 20, but for convenience of illustration, only the positive electrode base material 211 of the positive electrode plate 21 is shown, and the negative electrode plate 22 and the separator 23 are omitted. That is, in the electrode plate group 20, the positive electrode plate 21, the negative electrode plate 22 and the separator 23 are laminated from the center in the longitudinal direction to the position P3, and the positive electrode plate 21 and the separator 23 are laminated from the position P3 to the position P2. Only the positive electrode base material 211 is laminated from P2 to the position P1. The lead portion 214 does not face at least the negative electrode plate 22 and the separator 23. The lead portion 214 can bend the positive electrode base material 211 in the stacking direction between the position P3 and the position P1 where the negative electrode plate 22 is not arranged.

The laminated positive electrode base materials 211 are arranged so as to be spaced apart from each other in the stacking direction between the position P3 and the position P1. At this time, the positive electrode plates 21 are laminated so that the positions P1 of the end sides of the positive electrode base material 211, which is the tip end portion of the positive electrode plate 21, are aligned at the same positions in the stacking direction.

As shown in FIG. 5, in the lead portion 214, the tip portions 211C of the plurality of positive electrode base materials 211 are bent and assembled in the stacking direction so as to abut the tip portions 211C of the adjacent positive electrode base materials 211. For example, the positive electrode base material 211 is bent so that the position P1 of the tip portion 211C of the positive electrode base material 211 is gathered at the central CH with respect to the stacking direction of the electrode plate group 20. At this time, the curved portion K3 of the positive electrode base material 211 separated from the central CH of the electrode plate group 20 in the stacking direction becomes long, and the curved portion K3 of the positive electrode base material 211 located in the central CH of the electrode plate group 20 becomes short. Therefore, when assembled on the central CH, the position P1 of the tip portion 211C of each positive electrode base material 211 is such that the central CH projects in the longitudinal direction of the electrode plate group 20 with respect to the stacking direction and the distance from the central CH increases. A stepped portion K1 that is shortened stepwise is formed.

By gathering each tip portion 211C in the center and providing the curved portion K3, the mechanical strength (rigidity) of the lead portion 214 can be increased as compared with the case where the lead portion 214 is linear. Therefore, the current collector plate 14 can be easily attached to the lead portion 214.

Further, all the tip portions 211C are laminated between the stepped portion K1 and the curved portion K3 where the tip portions 211C are assembled, and the rigidity is increased by the binding force generated by the mutual contact of the tip portions 211C. Is formed. The laminated portion K2 may be joined and restrained to further increase the rigidity of the lead portion 214. In the present embodiment, the foil collecting portion 30 is composed of the laminated portion K2 and the tip portion 31 thereof.

The foil collecting portion 30 includes a collecting portion 32 to which the current collecting plate 14 is connected and a tip portion 31 after being trimmed in the lead portion 214.
As shown in FIG. 3, in the foil collecting portion 30, all of the upper end portion 214a and the lower end portion 214b are joined. The foil collecting portion 30 may be provided at least in a part between the upper end portion 214a and the lower end portion 214b of the lead portion 214. That is, the foil collecting portion 30 may be joined continuously between the upper end portion 214a and the lower end portion 214b, or may be joined at predetermined intervals. For bonding, interfacial bonding by ultrasonic bonding is preferable because there is a risk of breakage if the positive electrode base material 211 which is a thin film is melted.

(Disconnect)
By the way, the stepped portion K1 is a portion in which all the tip portions 211C are not laminated and does not affect the battery performance. Therefore, cutting is performed at the position P4, which is the shortest stepped portion K1, or at a position inside the position P4. Cutting is performed with a Thomson mold, an ultrasonic cutter, a mold, or the like. As a result, the foil collecting portion 30 includes a collecting portion 32 and a tip portion 31 formed from the lead portions 214 cut and aligned in the stacking direction at the position P4. By cutting the stepped portion K1, the longitudinal direction of the electrode plate group 20 can be shortened, so that the secondary battery 10 can be downsized or the capacity of the secondary battery 10 can be increased.

(Manufacturing method of secondary battery)
A procedure for manufacturing a secondary battery will be described with reference to FIG. 6 based on a flowchart.

When the method for manufacturing the secondary battery is started, a laminating step is executed in which the positive electrode plate 21, the negative electrode plate 22, and the separator 23 are laminated while maintaining their flat surfaces (step S10). For example, in the laminating step, the positive electrode plate 21 housed in the bag-shaped separator 23 and the negative electrode plate 22 are alternately laminated.

Next, a terminal assembly step of assembling the tip portion 211C of the positive electrode plate 21 and the tip portion 221C of the negative electrode plate 22 is executed (step S11).
Further, a foil collecting portion forming step of forming the foil collecting portion 30 by joining the tip portion 211C of the assembled positive electrode plate 21 and the tip portion 221C of the negative electrode plate 22 by interfacial bonding is executed (step S12).

When the foil collecting portion 30 is formed, an end cutting step of cutting the stepped portion K1 of the lead portion 214 of the positive electrode and the lead portion 224 of the negative electrode is executed (step S13). As a result, an unnecessary portion is removed from the foil collecting portion 30, and a collecting portion 32 to which the current collecting plate 14 is connected and a tip portion 31 after being trimmed are provided.

When an unnecessary portion is removed from the foil collecting portion 30, a current collecting plate contacting step of attaching the current collecting plate 14 to the foil collecting portion 30 is executed (step S14). Explaining with reference to FIG. 3, the foil collecting portion 30 of the electrode plate group 20 is sandwiched by a slide in the slit 141 formed in the current collecting plate 14. First, the lid 12 is arranged with the tip 14A of the current collector plate 14 facing the upper end 214a of the electrode plate group 20. Next, the lid body 12 is relatively moved so that the lid body 12 and the electrode plate group 20 are close to each other, and the foil collecting portion 30 formed at the upper end portion 214a of the lead portion 214 at the tip end 14A of the current collector plate 14 Plug in. Further, by bringing the electrode plate group 20 and the lid 12 relatively close to each other, the tip 14A of the current collector plate 14 is moved to the central portion 214c of the foil collecting portion 30, and subsequently moved to the vicinity of the lower end portion 214b. Let me. Along with this, the sandwiching portion 14B moves the foil collecting portion 30 from the upper end portion 214a to the central portion 214c. Since the width of the slit 141 is narrow in the sandwiching portion 14B, the foil collecting portion 30 sandwiched in the slit 141 is sandwiched between the first extending piece 142 and the second extending piece 143 to pressurize the sandwiching portion 14B. to bound. Further, the base end portion 14C of the slit 141 is arranged at the upper end portion 214a. The width of the slit 141 of the base end portion 14C is wider than that of the sandwiching portion 14B, and the foil collecting portion 30 is not pressurized and is not restrained. Therefore, stress or the like is applied to the upper end portion 214a of the foil collecting portion 30. Is suppressed.

When the current collector plate 14 is attached to the foil collecting portion 30, a welding step of welding the sandwiching portion 14B of the slit 141 of the current collecting plate 14 to the collecting portion 32 of the foil collecting portion 30 is executed (step S15). In the welding process, the current collector plate 14 is welded to the foil collecting portion 30 by laser welding. By sandwiching the foil collecting portion 30 into the slit 141 of the current collecting plate 14, the conductivity between the current collecting plate 14 and the foil collecting portion 30 is ensured. Further, since the foil collecting portion 30 has higher rigidity than the tip portion 211C alone by gathering the tip portions 211C, the foil collecting portion 30 can be sandwiched between the current collector plates 14 and the foil is collected. The current collector plate 14 can be easily attached to the portion 30. In order to obtain this effect, it is particularly preferable that the foil collecting portion 30 is configured to include the upper end portion 214a. Further, since the foil collecting portion 30 has a large heat capacity, it becomes easy to control the energy applied for welding. For example, at least a part of the foil collecting portion 30 and the current collecting plate 14 is welded by laser welding or the like, but since the foil collecting portion 30 plays a role of suppressing the penetration of the laser, the laser is inside the electrode plate group 20. Can be suppressed from reaching. In order to obtain this effect, it is preferable that the foil collecting portion 30 is provided at a position where the laser is irradiated in the welding process.

When the attachment of the current collector plate 14 fixed to the lid 12 to the electrode plate group 20 is completed, the accommodating step of accommodating the electrode plate group 20 to which the lid 12 is attached into the battery case 11 from the opening is executed. (Step S16).

Then, the lid body 12 is aligned with the opening of the battery case 11, and the case sealing step of welding the lid body 12 to the battery case 11 to seal the battery case 11 is executed (step S17).

When the battery case 11 is sealed, a liquid injection step of injecting the non-aqueous electrolyte 27 into the battery case 11 is executed (step S18). The liquid injection is performed from the liquid injection port of the lid body 12. Then, the non-aqueous electrolyte 27 permeates the separator 23 of the electrode plate group 20, and the production of the secondary battery is completed.

As described above, according to the present embodiment, the effects described below can be obtained.
(1) In the laminated electrode plate group 20, the tip portions 211C and 221C are joined to form the foil collecting portion 30 before the current collecting plate 14 is fixed. Therefore, the positive electrode plate 21 or the negative electrode plate is formed. Since the 22s are connected to each other, it is possible to suppress the occurrence of misalignment between the electrode plates constituting the electrode plate group 20 at the time of manufacturing.

Further, since the tip portions 211C and 221C of each electrode plate are metal thin films having low rigidity, unintended deformation is likely to occur, but by using the foil collecting portion 30, the rigidity is increased and unintended deformation is suppressed. Further, by increasing the rigidity, it becomes easy to connect the foil collecting portion 30 and the current collecting plate 14.

Further, it is preferable that the current collector plate 14 is connected to all the tip portions 211C and 221C. However, since all the tip portions 211C and 221C are joined as the foil collecting portion 30 in advance, the current collector plate 14 is connected to the tip. It is easy to connect to the portions 211C and 221C, and the conductivity between each electrode plate and the current collector plate 14 is surely secured.

(2) Since the tip portions 211C and 221C are joined without being changed by the interfacial joining, the breakage of the metal foil is suppressed. That is, it is possible to reduce the possibility that the foil shape cannot be maintained by forming a spherical shape that gathers the surroundings due to melting, or that the thickness of the foil becomes uneven and easily breaks. Reliability is improved.

(3) In the lithium ion secondary battery, it is possible to suppress the occurrence of misalignment between the electrode plates constituting the electrode plate group 20 at the time of manufacture.
(4) By making the protruding length of the foil collecting portion 30 the minimum necessary length, it is possible to reduce the size of the secondary battery 10 and increase the capacity of the secondary battery 10.

(5) Since the foil collecting portion 30 can be sandwiched between the slits 141 of the current collecting plate 14, the conductivity between the current collecting plate 14 and the foil collecting portion 30 can be ensured. Further, the foil collecting portion 30 has higher rigidity than the single tip portions 211C and 221C due to the aggregation of the tip portions 211C and 221C. Therefore, the foil collecting portion 30 can be sandwiched between the current collecting plates 14, and the current collecting plate 14 can be easily attached to the foil collecting portion 30. Further, since the foil collecting portion 30 has a large heat capacity, it becomes easy to control the energy applied for welding. Therefore, for example, in laser welding, it is possible to suppress the possibility that the laser penetrates the foil collecting portion 30.

(Second embodiment)
A second embodiment of the laminated electrode plate group, the secondary battery, and the method for manufacturing the secondary battery will be described with reference to FIGS. 7 to 9. In the present embodiment, the point of connecting each foil collecting portion of the plurality of electrode plate groups to one current collector plate is the first embodiment in which one electrode plate group 20 is connected to one current collector plate 14. Is different from.

As shown in FIG. 7, four electrode plate groups 40 are laminated.
Each electrode plate group 40 includes a foil collecting portion 60 on the positive electrode side at the lead portion of the positive electrode plate 21 in the longitudinal direction of the electrode plate group 40, and the lead portion of the negative electrode plate 22 on the negative electrode side in the longitudinal direction of the electrode plate group 40. The foil collecting portion 60 is provided. It is assumed that each foil collecting portion 60 has a paper surface on the upper end side, a back side on the paper surface on the lower end side, and extends from the upper end side to the lower end side.

In the present embodiment, the four electrode plate groups 40 have substantially the same structure, and the foil collecting portions 60 are aligned with respect to the stacking direction of the electrode plate group 40 and are spaced apart from each other. Are arranged in parallel.

Each foil collecting portion 60 forms a collecting portion 62 in which the tip portion of the positive electrode plate 21 or the tip portion of the negative electrode plate 22 is assembled, a tip portion 61 in which the stepped portion K1 is trimmed, and the collecting portion 62. It is provided with a curved portion 63 whose tip portion is bent.

The current collector plate 14 will be described with reference to FIG. Since the positive electrode current collector plate 14 and the negative electrode current collector plate 14 have the same structure, they are not distinguished here and will be described as the current collector plate 14.

The current collector plate 14 includes four slits 141 formed in the vertical direction. Each of the four slits 141 is for arranging the foil collecting portion 60, and has a similar structure. The slit 141 is provided with a first extension piece 142 at the left end and a second extension piece 143 at the right end in FIG. Further, between the first extension piece 142 and the second extension piece 143, third to fifth extension pieces 144 to 146 are provided. Since the third to fifth extension pieces 144 to 146 have the same shape, the third extension piece 144 will be described in detail.

The third extension piece 144 has the same shape as the second extension piece 143 on the right side in FIG. 8 and the same shape as the first extension piece 142 on the left side of the same. Further, the third extension piece 144 is formed so that the width in the left-right direction orthogonal to the vertical direction can sandwich the foil collecting portion 60 of the electrode plate group 40. Similarly, the fourth and fifth extension pieces 145 and 146 each have the same shape as the second extension piece 143 on the right side in FIG. 8 and the same shape as the first extension piece 142 on the left side. Have.

Therefore, each slit 141 of the current collector plate 14 has the same shape as the second extension piece 143 on the right side and the same shape as the first extension piece 142 on the left side, and the tip 14A And a sandwiching portion 14B and a base end portion 14C.

Then, the current collector plate 14 fixed to the lid 12 is attached to the four laminated electrode plate groups 40.
A procedure for manufacturing a secondary battery will be described with reference to FIG. 9 based on a flowchart.

When the method for manufacturing the secondary battery is started, the plate group preparation step for producing a plurality of plate groups is executed (step S20 in FIG. 9). In the electrode plate group preparation step, the laminating step (step S10 in FIG. 6), the terminal portion gathering step (step S11 in FIG. 6), and the foil collecting portion forming step (step S12 in FIG. 6) described in the first embodiment. ) And the end cutting step (step S13 in FIG. 6) to prepare each electrode plate group 40.

Next, a plate group laminating step of laminating the four produced electrode plate groups 40 is executed (step S21 in FIG. 9). In the electrode plate group laminating step, the four electrode plate groups 40 produced are laminated so that the foil collecting portions 60 are at the same position with respect to the laminating direction and are parallel to each other at predetermined intervals. Further, when the four electrode plate groups 40 are laminated, at least one separator 23 is arranged between the electrode plate groups 40. For example, between the electrode plate group 40, one separator 23 may be laminated so as to be sandwiched, or two separators 23 may be laminated so as to be sandwiched between them. Even if two separators 23 are sandwiched between the electrode plate group 40, there is little possibility that the battery performance will be affected.

When the four electrode plate groups 40 are laminated, a current collector plate contact step of attaching the current collector plate 14 to the foil collecting portion 60 of the electrode plate group 40 is executed (step S22 in FIG. 9). Each of the foil collecting portions 60 of the four electrode plate groups 40 is sandwiched between the four slits 141 formed in the current collecting plate 14 by sliding the current collecting plate 14.

When each current collecting plate 14 is attached to the four foil collecting portions 60, a welding step of welding the sandwiching portion 14B of the slit 141 of the current collecting plate 14 to the collecting portion 62 of each foil collecting portion 60 is executed (FIG. FIG. Step S23 of 9. In the welding process, the foil collecting portions 60 sandwiched by the current collector plates 14 are welded by laser welding. The four foil collecting portions 60 may be laser-welded to the current collector plate 14 at the same time, or the four foil collecting portions 60 may be laser-welded one by one.

When the attachment of the four electrode plate groups 40 to the current collector plate 14 fixed to the lid 12 is completed, the assembling step of assembling the four electrode plate groups 40 as the secondary battery 10 is executed (step S24 in FIG. 9). .. In the assembling step, two through the accommodating step (step S16 in FIG. 6), the case sealing step (step S17 in FIG. 6), and the liquid injection step (step S18 in FIG. 6) described in the first embodiment. The next battery 10 is assembled. Then, the non-aqueous electrolyte 27 permeates the separators 23 of the plurality of electrode plate groups 40, and the production of the secondary battery is completed.

As described above, according to the present embodiment, in addition to the effects (1) to (5) described in the first embodiment, the effects described below can be obtained.
(6) The foil collecting portions 60 of the plurality of electrode plate groups 40 are welded to the current collecting plate 14. Therefore, it is easy to construct a secondary battery having a plurality of electrode plate groups 40.

(7) By providing a plurality of electrode plate groups 40, the curved portion K3 can be shortened as compared with the case where these are one electrode plate group, so that the stepped portion K1 to be cut can be shortened. , The length of the tip portion of the positive electrode plate 21 and the negative electrode plate 22 which are uncoated portions can be shortened.

(8) By increasing or decreasing the number of the electrode plate group 40, it becomes possible to manufacture secondary batteries having different battery capacities.
(Other embodiments)
It should be noted that each of the above embodiments can also be implemented in the following embodiments.

-In the second embodiment, the case where the four electrode plate groups 40 are laminated has been illustrated, but the case is not limited to this, and the laminated electrode plate groups may be two, three, or five or more. There may be.
-In each of the above embodiments, the case where the foil collecting portion 30 has a trimmed tip portion 31 has been illustrated, but the present invention is not limited to this, and the foil collecting portion may not have the tip portion trimmed.

-In each of the above embodiments, the case where the foil collecting portions 30 and 60 of the lead portion 214 are joined between the upper end portion 214a and the lower end portion 214b has been illustrated. However, the present invention is not limited to this, and since the foil collecting portion of the lead portion may be provided at least in a part between the upper end portion and the lower end portion, for example, the position where the tip of the current collector plate reaches from the upper end portion. It may be joined between the two. In other words, the lead portion does not have to be provided with a foil collecting portion between the lower end portion and the tip of the current collector plate.

For example, when the current collector plate 14 does not reach the lower end of the lead portion 214 as shown in FIG. 10, the foil collecting portion 30 is set to the vicinity of the position where the tip 14A of the current collector plate 14 reaches, and the position where the tip 14A reaches. It is not necessary to provide the foil collecting portion 30 from the vicinity to the lower end portion.

That is, as shown in FIG. 5, in the portion where the foil collecting portion 30 is provided, the end portion of the positive electrode base material 211 of the lead portion 214 is closed, while the portion where the foil collecting portion 30 is not provided is , As shown in FIG. 4, the end portion of the positive electrode base material 211 of the lead portion 214 is open. Since the protruding tip side of the lead portion 214 is open, the non-aqueous electrolyte 27 can be easily permeated into the electrode plate group 20 from the open tip side. In particular, by not providing the foil collecting portion 30 in the lead portion 214 arranged under the battery case 11 in which the non-aqueous electrolyte 27 stays, the non-aqueous electrolyte can be obtained even in the electrode plate group 20 provided with the foil collecting portion 30. The permeability of 27 can be maintained high.

Further, since the tip 14A of the current collector plate 14 is inserted into the upper end portion 214a of the lead portion 214, it is preferable that the foil collecting portion 30 is formed at the upper end portion 214a.
The portion of the lead portion 214 where the foil collecting portion 30 is provided may be a portion suitable for attaching the current collector plate.

For example, in the case of so-called "end face current collecting" in which the flat surface of the current collecting plate is pressed against the end face of the foil collecting portion 30 and welded, the rigidity of the foil collecting portion 30 is increased, so that the current collecting plate is applied to the foil collecting portion 30. Can be welded by pressing with an appropriate pressing force. At this time, if the lead portion 214 is composed of a plurality of thin films that are not joined, the thin film having low rigidity may be deformed or the end portion may be short, so that the current collector plate may not be properly welded. .. Therefore, the foil collecting portion 30 may be provided at a portion where the current collecting plate is welded by a laser or the like, and may not be provided at the upper end portion 214a, for example.

-In each of the above embodiments, the case where the current collector plate 14 and the foil collecting portions 30 and 60 are laser welded has been illustrated, but the present invention is not limited to this, and the current collector plate and the foil collecting portion may be electron beam welded. However, resistance welding may be performed.

-In each of the above embodiments, the case where the lead portion 214 is collected in the central CH has been illustrated, but the present invention is not limited to this, and if a foil collecting portion to which a current collector plate can be attached can be formed, the lead portion can be used. It may be collected in a position off the center.

-In each of the above embodiments, the case where the lead portion 214 is collected at one location on the central CH has been illustrated, but the present invention is not limited to this, as long as a foil collecting portion to which a current collector plate can be attached can be formed. The lead portions may be collected at a plurality of locations and the foil collecting portions may be formed at a plurality of locations.

-In each of the above embodiments, the case where the foil collecting portions 30 and 60 are provided on both sides of the electrode plate groups 20 and 40 has been illustrated. However, the present invention is not limited to this, and a foil collecting portion may be provided on either one of the electrode plates. This also makes it possible to suppress the stacking deviation of the electrode plates to some extent.

-In each of the above embodiments, the case where the current collector plate 14 as the current collector is a plate-shaped member has been illustrated, but the present invention is not limited to this, and the current collector may be columnar or the like if it can be connected to the foil collector. It may have a shape other than a plate shape.

-In each of the above embodiments, the case where the secondary battery 10 is a lithium ion secondary battery has been illustrated, but the present invention is not limited to this, and other non-aqueous electrolyte secondary batteries, nickel hydrogen secondary batteries, nickel cadmium batteries, and the like can be used. It may be an alkaline secondary battery or another secondary battery.

-The secondary battery 10 is not limited to being mounted on an electric vehicle or a hybrid vehicle, and may be mounted on a vehicle such as a gasoline vehicle or a diesel vehicle, a moving body such as a railroad, a ship, or an aircraft, or a robot. It may be used as a power source for an information processing device or the like.

10 ... secondary battery, 11 ... battery case, 12 ... lid, 13 ... external terminal, 14 ... current collector plate, 14A ... tip, 14B ... sandwiching part, 14C ... base end part, 14D ... fixed part, 20 ... pole Plate group, 21 ... Positive electrode plate, 22 ... Negative electrode plate, 23 ... Separator, 27 ... Non-aqueous electrolyte, 30 ... Foil collecting part, 31 ... Tip part, 32 ... Collecting part, 40 ... Electrode plate group, 60 ... Foil collecting part , 61 ... Tip part, 62 ... Assembling part, 63 ... Curved part, 140 ... Extension part, 141 ... Slit, 142 ... First extension piece, 143 ... Second extension piece, 144 ... Third extension piece, 145 ... 4th extension piece, 146 ... 5th extension piece, 211 ... Positive electrode base material, 211A ... 1st surface, 211B ... 2nd surface, 211C ... Tip portion, 212,213 ... Positive electrode mixture, 214,224 ... Lead portion, 214a ... Upper end portion, 214b ... Lower end portion, 214c ... Central portion, 221 ... Negative electrode base material, 221A ... First surface, 221B ... Second surface, 221C ... Tip portion, 222, 223 ... Negative electrode mixture.

Claims (4)

A method for manufacturing a secondary battery having a group of electrode plates in which a positive electrode plate and a negative electrode plate are laminated with a separator sandwiched between them.
Each of the terminal portions of the electrode plate group, the terminal portion in which only the positive electrode plate is arranged in the laminated direction, or the terminal portion in which only the edge portion of the negative electrode plate is arranged. The edge gathering step of collecting the edge parts in the laminated direction, and
A foil collecting portion forming step of joining a plurality of collected terminal portions to form a foil collecting portion,
A contact step in which the current collector is brought into contact with the foil collector, and
A welding process for welding a portion where the foil collecting portion and the current collecting portion are in contact with each other,
A housing step of accommodating the electrode plate group in which the current collecting portion is welded to the foil collecting portion in the case of the secondary battery is provided.
In the foil collecting portion forming step, the two end edges facing each other in the laminated direction are interfacially joined to each other.
In the abutting step, the current collecting portion is brought into contact with the foil collecting portion by sandwiching the foil collecting portion in a slit extending in the longitudinal direction of the current collecting portion.
In the welding step, a method for manufacturing a secondary battery in which the current collector is welded to at least a part of the foil collector along the slit of the current collector. In the foil collecting portion forming step, only a predetermined length from the base end portion, which is the end portion near the upper side of the case, and the tip end portion, which is the end portion near the lower side of the case, with respect to the longitudinal direction of the terminal portion. The method for manufacturing a secondary battery according to claim 1, wherein the foil collecting portion is formed at least in a part between the position close to the base end portion. Prior to the accommodating step, the protruding portion of the terminal portion is cut at a predetermined position in the projecting direction, and is cut and aligned at the predetermined position where all the terminal portions are laminated in the laminated direction. The method for manufacturing a secondary battery according to claim 1 or 2, further comprising a process. Prior to the contact step, a electrode plate group laminating step of laminating a plurality of the electrode plate groups is provided.
In the abutting step, each of the foil collecting portions of the plurality of electrode plates is sandwiched between the plurality of slits extending in the longitudinal direction of the current collecting portion, so that the current collecting portion is formed in the foil collecting portion. The method for manufacturing a secondary battery according to any one of claims 1 to 3, which is in contact with the secondary battery.

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