Battery cell and manufacturing method thereof

Abstract

To provide: a battery cell in which a good laser welded portion between an electrode tab and a current collector is formed; and a manufacturing method thereof.SOLUTION: A battery cell includes: a case including a main body having an opening and a sealing plate for sealing the main body; an electrode body housed in the case and having an electrode tab; and a current collector connected to the electrode tab. The electrode tab has a laminated structure of metal foils, and a plurality of burring portions along a lamination direction of the metal foils are formed on the electrode tab. A laser welded portion that joins the electrode tab and the current collector is formed in a region located between at least the plurality of burring portions or a region adjacent to at least the plurality of burring portions.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present technology relates to a battery cell and a method for manufacturing the same. [Background technology]

[0002] Japanese Patent Application Publication No. 2019-207767 (Patent Document 1) discloses that a protective member having multiple holes penetrating in the stacking direction of the tabs is used at the welded portion between the tab group of the electrode body and the conductive member, and a laser irradiation device is moved across the multiple holes.

[0003] Japanese Patent No. 6784232 (Patent Document 2) discloses a structure in which a laminated metal foil constituting an electrode tab of a secondary battery is welded to a pair of metal plates, in which the laminated metal foil sandwiched between the pair of metal plates is locally pressed in the stacking direction at the intended welding location to be crimped.

[0004] Japanese Patent Application Publication No. 2013-166182 (Patent Document 3) discloses a method in which a cutter with a roughly V-shaped cross section is used to make a cut that penetrates the welded portion of stacked metal foil along the stacking direction, and the metal foils are tightly adhered to each other in the stacking direction at the ends of the cut. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-207767 A [Patent Document 2] Patent No. 6784232 [Patent Document 3] JP 2013-166182 A Summary of the Invention [Problem to be solved by the invention]

[0006] From the viewpoint of forming a good laser weld between the electrode tab and the current collector, there is still room for improvement in the conventional joining structure. The present inventors have investigated a structure capable of forming a good laser weld from a viewpoint different from that of the conventional structure.

[0007] An object of the present technology is to provide a battery cell in which good laser welds are formed between electrode tabs and current collectors, and a method for manufacturing the same. [Means for solving the problem]

[0008] The battery cell according to the present technology includes a case including a main body having an opening and a sealing plate sealing the main body, an electrode body housed in the case and having an electrode tab, and a current collector joined to the electrode tab. The electrode tab has a laminated structure of metal foil, and a plurality of burred portions are formed on the electrode tab along the lamination direction of the metal foil. A laser weld portion that joins the electrode tab and the current collector is formed at least in an area located between the plurality of burred portions or at least in an area adjacent to the plurality of burred portions.

[0009] A manufacturing method for a battery cell according to the present technology includes the steps of: preparing an electrode body including an electrode tab having a laminated structure of metal foil; arranging a current collector on the electrode tab; performing burring on the electrode tab along the laminated direction of the metal foil at a first position and a second position spaced apart from each other; joining the electrode tab and the current collector by laser welding at least in a region located between the first position and the second position or at least in a region adjacent to the first position and the second position; accommodating the electrode body and the current collector in a case body after joining the electrode tab and the current collector; and sealing the case body accommodating the electrode body and the current collector with a sealing plate. Effect of the Invention

[0010] According to this technology, at the joint between the electrode tab and current collector of the battery cell, laser welding can be performed with no gaps or with the gaps minimized in the laminated structure of the metal foil that constitutes the electrode tab by using burring processing, so that it is possible to form an excellent laser weld between the electrode tab and the current collector. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a perspective view showing a battery cell. [Diagram 2] 4 is a cross-sectional view of the battery cell as viewed from the Y-axis direction. [Diagram 3] FIG. 2 is a schematic diagram showing an example of the configuration of an electrode body. [Figure 4] FIG. 1 is a diagram (part 1) showing a joint between an electrode tab and a current collector. [Diagram 5] FIG. 2 is a diagram (part 2) showing the joint between the electrode tab and the current collector. [Figure 6] FIG. 3 is a diagram (part 3) showing the joint between the electrode tab and the current collector. [Figure 7] FIG. 4 is a diagram showing the joint between the electrode tab and the current collector. [Figure 8] FIG. 5 is a diagram (part 5) showing the joint between the electrode tab and the current collector. [Figure 9] FIG. 6 is a diagram showing the joint between the electrode tab and the current collector. [Figure 10] FIG. 7 is a diagram showing the joint between the electrode tab and the current collector. [Figure 11] FIG. 8 is a diagram showing the joint between the electrode tab and the current collector. [Figure 12] 4 is a cross-sectional view showing the periphery of a burred portion of an electrode tab according to one embodiment. FIG. [Figure 13] 4 is an enlarged cross-sectional view showing a schematic structure of the periphery of a burred portion of an electrode tab; FIG. [Figure 14] 11 is a cross-sectional view showing the periphery of a burred portion of an electrode tab according to a comparative example. FIG. [Figure 15] FIG. 1 is a diagram (part 1) for explaining the dimensional relationship around a laser welded portion. [Figure 16]FIG. 2 is a second diagram for explaining the dimensional relationship around the laser welded portion. [Figure 17] FIG. 3 is a diagram (part 3) for explaining the dimensional relationship around the laser welded portion. [Figure 18] FIG. 4 is a diagram (part 4) for explaining the dimensional relationship around the laser welded portion. [Figure 19] FIG. 2 is a flow diagram showing each step of a manufacturing method of a battery cell. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof will not be repeated.

[0013] In the embodiments described below, when referring to the number, amount, etc., the scope of the present technology is not necessarily limited to the number, amount, etc., unless otherwise specified. In addition, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. In addition, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiment.

[0014] In this specification, the words "comprise", "include" and "have" are open-ended, i.e., when a certain configuration is included, other configurations may or may not be included.

[0015] Furthermore, when geometric terms and terms expressing positional and directional relationships, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along" are used in this specification, these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in one state, and the relative positional relationships can be inverted or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0016] In this specification, the term "battery" is not limited to lithium ion batteries, but may include other batteries such as nickel-metal hydride batteries and sodium ion batteries. In this specification, the term "electrode" may collectively refer to a positive electrode and a negative electrode.

[0017] In this specification, the term "battery cell" is not necessarily limited to a rectangular shape, but may also include cells of other shapes, such as a cylindrical shape.

[0018] The "battery cell" can be installed in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs), etc. However, the use of the "battery cell" is not limited to in-vehicle use.

[0019] Fig. 1 is a perspective view showing a battery cell 100. As shown in Fig. 1, the battery cell 100 has a rectangular shape. The battery cell 100 has an electrode terminal 110 and a housing 120 (external can). In other words, the battery cell 100 is a rectangular secondary battery cell.

[0020] The electrode terminal 110 is formed on the housing 120. The electrode terminal 110 has a positive electrode terminal 111 and a negative electrode terminal 112 aligned along an X-axis direction (second direction) perpendicular to a Y-axis direction (first direction). The positive electrode terminal 111 and the negative electrode terminal 112 are provided apart from each other in the X-axis direction.

[0021] The housing 120 has a rectangular parallelepiped shape and forms the external appearance of the battery cell 100. The housing 120 includes a case body 120A and a sealing plate 120B that seals the opening of the case body 120A. The sealing plate 120B is joined to the case body 120A by welding.

[0022] The housing 120 has an upper surface 121, a lower surface 122, a first side surface 123, a second side surface 124, and two third side surfaces 125. The housing 120 is provided with a gas exhaust valve 126.

[0023] The upper surface 121 is a plane perpendicular to the Z-axis direction (third direction) perpendicular to the Y-axis direction and the X-axis direction. The electrode terminals 110 are disposed on the upper surface 121. The lower surface 122 faces the upper surface 121 along the Z-axis direction.

[0024] Each of the first side surface 123 and the second side surface 124 is formed of a plane perpendicular to the Y-axis direction. Each of the first side surface 123 and the second side surface 124 has the largest area among the multiple side surfaces of the housing 120. Each of the first side surface 123 and the second side surface 124 has a rectangular shape when viewed in the Y-axis direction. Each of the first side surface 123 and the second side surface 124 has a rectangular shape with the X-axis direction being the long side direction and the Z-axis direction being the short side direction when viewed in the Y-axis direction.

[0025] When multiple battery cells 100 are connected in series, the multiple battery cells 100 are stacked such that the first side surfaces 123 and the second side surfaces 124 of the battery cells 100 adjacent to each other in the Y-axis direction face each other. As a result, the positive electrode terminals 111 and the negative electrode terminals 112 are arranged alternately in the Y-axis direction in which the multiple battery cells 100 are stacked.

[0026] Gas exhaust valve 126 is provided on top surface 121. When the temperature of battery cell 100 rises abnormally (thermal runaway) and the internal pressure of housing 120 exceeds a predetermined value due to gas generated inside housing 120, gas exhaust valve 126 exhausts the gas to the outside of housing 120.

[0027] Fig. 2 is a schematic diagram showing an example of the configuration of an electrode body. As shown in Fig. 2, in a battery cell 100, an electrode body 130, a current collecting member 140, and an electrolyte (not shown) are stored inside a case 120. The current collecting member 140 includes a positive current collecting member 141 and a negative current collecting member 142.

[0028] The electrode terminal 110 is fixed to the sealing plate 120B via a resin insulating member 150. The insulating member 150 includes an insulating member 151 on the positive electrode side and an insulating member 152 on the negative electrode side.

[0029] The electrode terminal 110 and the electrode body 130 are electrically connected via a current collecting member 140. Specifically, the electrode body 130 is connected to the positive terminal 111 by a positive current collecting member 141. The electrode body 130 is connected to the negative terminal 112 by a negative current collecting member 142.

[0030] A positive electrode tab 130A and a negative electrode tab 130B are formed on both ends in the X-axis direction of the electrode body 130. The positive electrode tab 130A is joined to a positive electrode current collecting member 141 at joint 1A. The negative electrode tab 130B is joined to a negative electrode current collecting member 142 at joint 1B.

[0031] 2, the positive electrode tab 130A and the negative electrode tab 130B are formed separately on both sides in the X-axis direction with respect to the electrode body 130, but the arrangement of the positive electrode tab 130A and the negative electrode tab 130B is not limited to this. For example, the positive electrode tab 130A and the negative electrode tab 130B may be arranged on the sealing plate 120B side of the electrode body 130 in the Z-axis direction (upper side in FIG. 2).

[0032] Fig. 3 is a schematic diagram showing an example of the configuration of the electrode body 130. In the example shown in Fig. 3, the electrode body 130 is of a wound type. The electrode body 130 is not limited to the wound type, and may be of a layered type (stack type).

[0033] In the example of FIG. 3, the electrode body 130 includes a positive electrode 131A, a negative electrode 131B, and a separator 131C. The positive electrode 131A, the negative electrode 131B, and the separator 131C are all strip-shaped sheets. The electrode body 130 may include a plurality of separators 131C. The separator 131C is sandwiched between the positive electrode 131A and the negative electrode 131B. The electrode body 130 is formed by spirally winding a laminate of the positive electrode 131A, the negative electrode 131B, and the separator 131C. The electrode body 130 may be formed into a flat shape after winding.

[0034] The positive electrode 131A includes a positive electrode substrate 1311A and a positive electrode active material layer 1312A. The positive electrode substrate 1311A is a conductive sheet. The positive electrode substrate 1311A may be, for example, an aluminum alloy foil. The positive electrode substrate 1311A may have a thickness of, for example, about 10 μm to 30 μm. The positive electrode active material layer 1312A is disposed on the surface of the positive electrode substrate 1311A. The positive electrode active material layer 1312A may be disposed on only one side of the positive electrode substrate 1311A. The positive electrode active material layer 1312A may be disposed on both sides of the positive electrode substrate 1311A. The positive electrode substrate 1311A may be exposed at one end in the width direction (X-axis direction) of the positive electrode 131A. A positive electrode current collecting member 141 is joined to the exposed portion of the positive electrode substrate 1311A.

[0035] For example, an intermediate layer (not shown) may be formed between the positive electrode active material layer 1312A and the positive electrode substrate 1311A. In this specification, even when an intermediate layer is present, the positive electrode active material layer 1312A is considered to be disposed on the surface of the positive electrode substrate 1311A. The intermediate layer may be thinner than the positive electrode active material layer 1312A. The intermediate layer may have a thickness of, for example, about 0.1 μm to 10 μm. The intermediate layer may include, for example, a conductive material, an insulating material, or the like.

[0036] The positive electrode active material layer 1312A may have a thickness of, for example, about 10 μm to 200 μm. The positive electrode active material layer 1312A may have a thickness of, for example, about 130 μm to 1130 μm. The positive electrode active material layer 1312A may have a thickness of, for example, about 130 μm to 100 μm.

[0037] The positive electrode active material layer 1312A includes a positive electrode active material. The positive electrode active material is a particle group. The positive electrode active material layer 1312A may further include additional components as long as it includes a positive electrode active material. The positive electrode active material layer 1312A may include, in addition to the positive electrode active material, for example, a conductive material and a binder. The conductive material may include any component. The conductive material may include, for example, at least one selected from the group consisting of carbon black, graphite, vapor grown carbon fiber (VGCF), carbon nanotubes (CNT), and graphene flakes. The amount of the conductive material may be, for example, about 0.1 parts by mass to 10 parts by mass with respect to 100 parts by mass of the positive electrode active material. The binder may include any component. The binder may include, for example, at least one selected from the group consisting of polyvinylidene fluoride (PVdF), poly(vinylidene fluoride-co-hexafluoropropylene (PVdF-HFP), polytetrafluoroethylene (PTFE), and polyacrylic acid (PAA). The amount of the binder to be mixed may be, for example, about 0.1 parts by mass to 10 parts by mass relative to 100 parts by mass of the positive electrode active material.

[0038] The positive electrode active material layer 1312A may have a high density. For example, the positive electrode active material layer 1312A may have a density of 3.6 g / cm 3 from 3.9 g / cm 3 The positive electrode active material layer 1312A may have a density of about 3.65 g / cm 3 from 3.81 g / cm 3 The positive electrode active material layer 1312A may have a density of about 3.70 g / cm 3 from 3.81 g / cm 3 In this specification, the density of the active material layer refers to the apparent density.

[0039] The negative electrode 131B may include, for example, a negative electrode substrate 1311B and a negative electrode active material layer 1312B. The negative electrode substrate 1311B is a conductive sheet. The negative electrode substrate 1311B may be, for example, a copper alloy foil. The negative electrode substrate 1311B may have a thickness of, for example, about 5 μm to 30 μm. The negative electrode active material layer 1312B may be disposed on the surface of the negative electrode substrate 1311B. The negative electrode active material layer 1312B may be disposed on only one side of the negative electrode substrate 1311B. The negative electrode active material layer 1312B may be disposed on both the front and rear sides of the negative electrode substrate 1311B. The negative electrode substrate 1311B may be exposed at one end in the width direction (X-axis direction) of the negative electrode 131B. The negative electrode current collecting member 142 is joined to the part where the negative electrode substrate 1311B is exposed.

[0040] The negative electrode active material layer 1312B may have a thickness of, for example, about 10 μm to 200 μm. The negative electrode active material layer 1312B includes a negative electrode active material. The negative electrode active material may include any component. The negative electrode active material may include at least one selected from the group consisting of, for example, graphite, soft carbon, hard carbon, silicon, silicon oxide, silicon-based alloy, tin, tin oxide, tin-based alloy, and lithium titanium composite oxide.

[0041] The negative electrode active material layer 1312B may further contain, for example, a binder in addition to the negative electrode active material. The negative electrode active material layer 1312B may contain, for example, approximately 95% to 99.5% by mass of the negative electrode active material, with the remainder being a binder. The binder may contain any component. The binder may contain, for example, at least one selected from the group consisting of carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR).

[0042] At least a portion of separator 131C is interposed between positive electrode 131A and negative electrode 131B. Separator 131C separates positive electrode 131A from negative electrode 131B. Separator 131C may have a thickness of, for example, about 10 μm to 30 μm.

[0043] The separator 131C is a porous sheet. The electrolyte permeates the separator 131C. The separator 131C may have an air permeability of, for example, about 200s / 100mL to 400s / 100mL. In this specification, the term "air permeability" refers to the "air resistance" defined in "JIS P 8117:2009." The air permeability is measured by the Gurley test method.

[0044] The separator 131C is electrically insulating. The separator 131C may contain, for example, a polyolefin resin. The separator 131C may be substantially made of a polyolefin resin. The polyolefin resin may contain, for example, at least one selected from the group consisting of polyethylene (PE) and polypropylene (PP). The separator 131C may have, for example, a single-layer structure. The separator 131C may be substantially made of a PE layer. The separator 131C may have, for example, a multi-layer structure. The separator 131C may be formed by laminating, for example, a PP layer, a PE layer, and a PP layer in this order. For example, a heat-resistant layer may be formed on the surface of the separator 131C.

[0045] The electrolyte includes a solvent and a supporting electrolyte. The solvent is aprotic. The solvent may include any component. The solvent may include at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), 1,2-dimethoxyethane (DME), methyl formate (MF), methyl acetate (MA), methyl propionate (MP), and γ-butyrolactone (GBL).

[0046] The supporting electrolyte is dissolved in the solvent. The supporting electrolyte may include at least one selected from the group consisting of LiPF6, LiBF4, and LiN(FSO2)2. The supporting electrolyte may have a molar concentration of, for example, about 0.5 mol / L to 2.0 mol / L. The supporting electrolyte may have a molar concentration of, for example, about 0.8 mol / L to 1.2 mol / L.

[0047] The electrolyte may further contain any additive in addition to the solvent and the supporting electrolyte. For example, the electrolyte may contain an additive in a mass fraction of about 0.01% to 5%. The additive may contain, for example, at least one selected from the group consisting of vinylene carbonate (VC), lithium difluorophosphate (LiPO2F2), lithium fluorosulfonate (FSO3Li), and lithium bis(oxalato)borate (LiBOB).

[0048] 3, the positive electrode substrate 1311A and the negative electrode substrate 1311B located at both ends in the X-axis direction of the electrode body 130 are collected into the positive electrode tab 130A and the negative electrode tab 130B, respectively. The positive electrode tab 130A and the negative electrode tab 130B have a laminated structure of metal foil.

[0049] Next, the structure of joint 1A between positive electrode tab 130A (electrode tab) and positive electrode current collector 141 (current collector) will be described with reference to Fig. 4. Note that, although the joint 1A on the positive electrode side will be described in Fig. 4 and Figs. 5 to 11, a similar structure can also be applied to joint 1B on the negative electrode side.

[0050] Fig. 4 is a diagram showing a joint 1A between a positive electrode tab 130A (electrode tab) and a positive electrode current collecting member 141 (current collector). Note that, although the joint 1A between the positive electrode tab 130A and the positive electrode current collecting member 141 will be described in Fig. 4 and Figs. 5 to 18 described later, a structure similar to that of the joint 1A can also be applied to the joint 1B between the negative electrode tab 130B and the negative electrode current collecting member 142.

[0051] As shown in FIG. 4, the joint 1A includes a plurality of burred portions 10 and a laser welded portion 20 formed in a region sandwiched between the plurality of burred portions 10.

[0052] The burring process portion 10 is formed on the positive electrode tab 130A in a state where the positive electrode tab 130A and the positive electrode current collecting member 141 are overlapped. The burring process portion 10 is formed along the lamination direction of the metal foil constituting the positive electrode tab 130A. In the example of Fig. 4, the burring process portion 10 is formed in a substantially circular shape when viewed from the lamination direction of the metal foil.

[0053] The laser weld 20 joins the positive electrode tab 130A and the positive electrode current collecting member 141. The laser weld 20 is formed along the horizontal direction in Fig. 4. The extension direction of the laser weld 20 in Fig. 4 (the horizontal direction in the figure) may be parallel to the X-axis direction, parallel to the Z-axis direction, or a direction that obliquely intersects the X-axis and Z-axis.

[0054] 5 to 11 are diagrams showing a joint 1A according to a modified example. Modified examples of the burred portion 10 and the laser welded portion 20 will be described with reference to Figs.

[0055] 5 to 7, two burring processed portions 10 are formed so as to be aligned horizontally in the drawings. The laser welded portion 20 is formed between the two burring processed portions 10 so as to extend in the direction in which the two burring processed portions 10 are aligned. In this manner, the number of the multiple burring processed portions 10 can be changed as appropriate.

[0056] In the example of FIG. 5, similarly to the example of FIG. 4, the burring processing portion 10 is formed in a substantially circular shape when viewed from the stacking direction of the metal foil. In the example of FIG. 6, the burring processing portion 10 is formed in a substantially triangular shape when viewed from the stacking direction of the metal foil. In the example of FIG. 7, the burring processing portion 10 is formed in a substantially rectangular shape when viewed from the stacking direction of the metal foil. The burring processing portion 10 may have other polygonal shapes, or may have, for example, an elliptical shape, when viewed from the stacking direction of the metal foil. In this way, the planar shape of the burring processing portion 10 can be changed as appropriate.

[0057] 4 to 7, the laser welded portion 20 is formed so as to be separated from the burred portion 10 when viewed from the lamination direction of the metal foil. In contrast, in the example of Fig. 8, a part of the laser welded portion 20 is formed so as to overlap with the burred portion 10 when viewed from the lamination direction of the metal foil.

[0058] As shown in Figures 9 and 10, the burring processing parts 10 may be arranged in a staggered manner. Furthermore, the burring processing parts 10 do not necessarily have to be arranged regularly. In this way, the arrangement of the burring processing parts 10 can be changed as appropriate.

[0059] In the example of Fig. 9, the laser welds 20 are formed so as to extend in the horizontal direction in the figure. In the example of Fig. 10, the laser welds 20 are formed so as to extend in a zigzag pattern between the staggered burred portions 10. In this manner, the extending direction and shape of the laser welds 20 can also be changed as appropriate.

[0060] 11, the laser welded portion 20 is formed in two parts between six burred portions 10 arranged in two rows (vertical direction in the figure) and three columns (horizontal direction in the figure). In this way, the laser welded portion 20 is not limited to being single in one joint 1A, and may be formed in multiple parts.

[0061] In the modified examples of Figures 5 to 11, similarly to the example of Figure 4, the horizontal and vertical directions in the figures may be parallel to the X-axis direction, parallel to the Z-axis direction, or may be directions that obliquely intersect the X-axis and Z-axis.

[0062] 12 is a cross-sectional view showing the periphery of the burred portion 10 of the positive electrode tab 130A according to one embodiment. Fig. 12 corresponds to the AA cross section in Fig. 4.

[0063] As shown in Fig. 12, the burring processing portion 10 has a tapered shape in which the processing width becomes narrower from the opening toward the tip. That is, the burring processing is performed so that the processing width becomes narrower toward the tip. However, the shape of the burring processing portion 10 is not limited to a tapered shape.

[0064] In the example of FIG. 12, the burring is performed so as to form a bottomed hole in the positive electrode tab 130A. The burring processing portion 10 has a processing depth H of about 50% or more of the total thickness T of the positive electrode tab 130A. The burring is performed so as to penetrate the positive electrode tab 130A. Carried out This may also be the case.

[0065] Adhesion regions 30 in which there is no gap or the gap is minimized in the laminated metal foil are formed between the multiple burring processed portions 10. By performing laser welding on the region including the adhesion region 30, the laser welded portion 20 between the positive electrode tab 130A and the positive electrode current collecting member 141 is formed.

[0066] 13 is an enlarged cross-sectional view showing a schematic structure of the periphery of the burred portion 10 of the positive electrode tab 130A. The width A of the opening of the burred portion 10 is, for example, about 0.7 mm. The width B of the adhesion region 30 located between the multiple burred portions 10 is, for example, about 1.5 mm.

[0067] Fig. 14 is a cross-sectional view showing the periphery of the burred portion 10 of the positive electrode tab 130A according to the comparative example. In Fig. 14, the metal foil of the positive electrode tab 130A is clamped by a plurality of clips 40. A gap 30B is formed in the metal foil located in the intermediate portion 30A between the plurality of clips 40. When laser welding is performed on the intermediate portion 30A in which the gap 30B is formed, welding defects are likely to occur in the laser welded portion 20.

[0068] In contrast, in the battery cell 100 according to this embodiment, by performing burring on the positive tab 130A located at the joint 1A with the positive current collecting member 141, laser welding can be performed with no gaps or with the gaps minimized in the laminated structure of the metal foil that constitutes the positive tab 130A. As a result, it is possible to form a good laser welded portion 20 between the positive tab 130A and the positive current collecting member 141. The same is true for the joint 1B between the negative tab 130B and the negative current collecting member 142.

[0069] More specifically, the metal foils are likely to come into close contact with each other due to burrs generated during burring, and the laminated structure of the metal foils can be bound together. In this regard, in a compression process in which the laminated structure of the metal foils is compressed to crush the metal foils, it is difficult to bind the metal foils close to the positive electrode current collector 141 and the negative electrode current collector 142 (current collectors), and gaps may be formed between the metal foils. In order to reliably avoid gaps between the metal foils, a fairly large compression load is required. In contrast, in the battery cell 100 according to this embodiment, burring (hole punching) is used instead of compression, and therefore a close contact structure between the metal foils can be obtained with a relatively small load compared to compression.

[0070] Furthermore, burring makes it possible to remove the oxide film from the metal foil before bundling it into a single piece. By bundling the metal foil into a single piece, the effects of thermal distortion (stretching and bending of the metal foil) during laser welding can be suppressed. When bundling metal foils by temporary welding, thermal distortion occurs in the metal foil, but burring does not cause thermal distortion.

[0071] Next, the dimensional relationship around the laser welded portion 20 will be described with reference to Figures 15 to 18. As shown in the schematic diagram of Figure 15 and the above-mentioned Figure 13, when the width (opening width) of the burred portion is A, the width of the adhesion region 30 is B, the beam diameter during laser welding is C, the distance (vertical direction) between the center of the burred portion 10 and the center of the laser beam is D, and the pitch of the burred portion 10 is Ex (horizontal direction) and Er (diagonal direction), typically, it is preferable that the following relationship holds (standard range).

[0072] A / 2+C / 2≦D≦A / 2+BC / 2 A+C≦Ex,Er <A+2×B

[0073] By satisfying the above relationship, as shown in FIG. 16, the area between the multiple burring processed portions 10 can be made into a contact area 30 without any gaps, and the burring processed portions 10 and the laser welded portions 20 can be prevented from overlapping.

[0074] 16, the width A of the burred part is 0.7 mm, the width B of the adhesion region 30 (area where there are no gaps in the metal foil) is 1.55 mm, the laser beam diameter C is 1.0 mm, the distance (vertical direction) D between the center of the burred part 10 and the center of the laser beam is 1.4 mm, the pitch Ex of the burred part 10 is 3.35 mm, Er is 3.26 mm, and the irradiation length L of the laser beam is 11.74 mm. However, the values ​​of A, B, C, D, Ex, Er, and L are not limited to these.

[0075] The laser beam diameter C can be changed as appropriate. For example, the laser beam diameter C can be changed as appropriate within a range of about 0.1 mm or more and 1.0 mm or less, but the range of the laser beam diameter C is not limited to this. The laser beam diameter C may be made smaller and scanned multiple times. For example, the laser beam may be irradiated three times with a laser beam diameter C = 0.2 mm. When irradiating the laser beam multiple times, it is irradiated with the center shifted from the already welded part. In this case, it may be irradiated while completely avoiding the already welded part, or it may be partially overlapped with the already welded part.

[0076] The width (opening width) A of the burring processed portion, the width B of the adhesion region 30, the beam diameter C during laser welding, the distance (vertical direction) D between the center of the burring processed portion 10 and the center of the laser beam, and the pitch Ex (horizontal direction) and Er (diagonal direction) of the burring processed portion 10 may satisfy the following relationship (limit range).

[0077] C / 2≦D≦A / 2+B Ex,Er=A+2×B

[0078] By satisfying the above relationship, as shown in FIG. 17, most of the area located between the multiple burring processed portions 10 can be made into an adhesion area 30, and the burring processed portions 10 and the laser welded portions 20 can be prevented from overlapping.

[0079] 17, the width A of the burred part is 0.7 mm, the width B of the adhesion region 30 (area where there are no gaps in the metal foil) is 1.55 mm, the laser beam diameter C is 1.0 mm, the distance (vertical direction) D between the center of the burred part 10 and the center of the laser beam is 1.65 mm, the pitch Ex of the burred part 10 is 3.8 mm, Er is 3.8 mm, and the irradiation length L of the laser beam is 11.4 mm. However, the values ​​of A, B, C, D, Ex, Er, and L are not limited to these.

[0080] Also, it is preferable that the laser beam diameter C is equal to or smaller than the width B of the adhesion region 30 (the range where there are no gaps in the metal foil). However, even if C×0.5≦B, the laser welded portion 20 can be formed.

[0081] It is preferable that the laser welded portion 20 does not overlap the burred portion 10. In other words, it is preferable that the laser beam is not irradiated onto the burred portion 10. However, by adjusting the laser output (to be relatively small), the laser welded portion 20 can be formed even if the laser welded portion 20 partially overlaps the burred portion 10.

[0082] 18, it is also possible to provide a laser welded portion 20 at a position adjacent to a plurality of burred portions 10 formed in a row. In this case, too, the laser welded portion 20 can be formed in the adhesion region 30 adjacent to the plurality of burred portions 10, and the burred portions 10 and the laser welded portion 20 can be prevented from overlapping.

[0083] In the example of FIG. 18, the laser welded portion 20 is formed so as to extend substantially parallel to the direction in which the plurality of burred portions 10 are arranged (the horizontal direction in the figure).

[0084] 18, the width A of the burred part is 0.7 mm, the width B of the adhesion region 30 (area where there are no gaps in the metal foil) is 1.55 mm, the laser beam diameter C is 1.0 mm, the distance (vertical direction) D between the center of the burred part 10 and the center of the laser beam is 0.9 mm, the pitch Ex of the burred part 10 is 2.57 mm, and the irradiation length L of the laser beam is 9.85 mm. However, the values ​​of A, B, C, D, Ex, and L are not limited to these.

[0085] 17 and 18, the laser beam diameter C and the number of times of irradiation can be appropriately changed, as in the case of Fig. 16. As described above, a part of the laser welded portion 20 may be formed outside the contact region 30 (a portion where there is no gap or the gap is minimized in the metal foil).

[0086] Fig. 19 is a flow diagram showing each step of a manufacturing method for a battery cell 100. As shown in Fig. 19, the manufacturing method for a battery cell includes a step (S10) of producing an electrode body 130 including a positive electrode tab 130A and a negative electrode tab 130B having a laminated structure of metal foil, a step (S20) of joining the positive electrode tab 130A and the negative electrode tab 130B of the electrode body 130 to a positive electrode current collecting member 141 and a negative electrode current collecting member 142, respectively, and a step (S30) of enclosing the electrode body 130, the positive electrode current collecting member 141, and the negative electrode current collecting member 142 in a housing 120.

[0087] The step (S20) of joining the electrode body 130 to the positive electrode current collecting member 141 and the negative electrode current collecting member 142 includes the steps of: arranging the positive electrode current collecting member 141 and the negative electrode current collecting member 142 on the positive electrode tab 130A and the negative electrode tab 130B (S21); burring the positive electrode tab 130A and the negative electrode tab 130B along the lamination direction of the metal foil at a plurality of positions (first position and second position) spaced apart from each other to form a plurality of burred processed portions 10 (S22); and joining the positive electrode tab 130A and the negative electrode tab 130B (electrode tabs) to the positive electrode current collecting member 141 and the negative electrode current collecting member 142 (current collectors) by laser welding in an adhesion region 30 located between the plurality of burred processed portions 10 or adjacent to the plurality of burred processed portions 10 (S23).

[0088] The step (S30) of enclosing the electrode body 130, the positive electrode current collecting member 141, and the negative electrode current collecting member 142 in the housing 120 includes a step (S31) of accommodating the electrode body 130, the positive electrode current collecting member 141, and the negative electrode current collecting member 142 that are joined together in the case body 120A, and a step (S32) of sealing the case body 120A accommodating the electrode body 130, the positive electrode current collecting member 141, and the negative electrode current collecting member 142 with a sealing plate 120B.

[0089] Although the embodiment of the present technology has been described above, the embodiment disclosed herein should be considered as illustrative and not restrictive in all respects. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0090] 1A, 1B joint, 10 burring processed portion, 20 laser welded portion, 30 adhesion region, 30A middle portion, 30B gap, 40 clip, 100 battery cell, 110 electrode terminal, 111 positive electrode terminal, 112 negative electrode terminal, 120 housing, 120A case body, 120B sealing plate, 121 upper surface, 122 lower surface, 123 first side surface, 124 second side surface, 125 third side surface, 126 gas exhaust valve, 130 electrode body, 130A positive electrode tab, 130B negative electrode tab, 131A positive electrode, 131B negative electrode, 131C separator, 140 current collecting member, 141 positive electrode current collecting member, 142 negative electrode current collecting member, 150, 151, 152 insulating member, 1311A Positive electrode base material, 1311B negative electrode base material, 1312A positive electrode active material layer, 1312B negative electrode active material layer.

Claims

1. a case including a main body having an opening and a sealing plate that seals the main body; an electrode body housed in the case and having an electrode tab; a current collector joined to the electrode tab; The electrode tab has a laminated structure of metal foil, a plurality of burring processed portions are formed in the electrode tab along a lamination direction of the metal foil so as to form bottomed holes; a laser welded portion that joins the electrode tab and the current collector is formed in at least a region located between the plurality of burring processed portions and where the metal foils are in close contact with each other, or in at least a region adjacent to the plurality of burring processed portions and where the metal foils are in close contact with each other, while leaving an opening in the burring processed portion.

2. a case including a main body having an opening and a sealing plate that seals the main body; an electrode body housed in the case and having an electrode tab; a current collector joined to the electrode tab; The electrode tab has a laminated structure of metal foil, A plurality of burring processed portions are formed on the electrode tab along a lamination direction of the metal foil, a laser welded portion is formed in at least a region between the plurality of burring processed portions where the metal foils are in close contact with each other, or in at least a region adjacent to the plurality of burring processed portions where the metal foils are in close contact with each other, the laser welded portion joining the electrode tab and the current collector being in a state where an opening of the burring processed portion is left; The laser welded portion is spaced apart from the burring processed portion when viewed from the lamination direction of the metal foil.

3. The battery cell according to claim 1 or 2, wherein the burred portion has a processing depth of 50% or more of a total thickness of the electrode tab.

4. The battery cell according to claim 1 , wherein the burring processed portion has a tapered shape in which a processed width narrows toward a tip end.

5. A step of producing an electrode body including an electrode tab having a laminated structure of metal foil; placing a current collector on the electrode tab; performing burring along a lamination direction of the metal foil so as to form bottomed holes in the electrode tabs at first and second positions spaced apart from each other; a step of joining the electrode tab and the current collector by laser welding while leaving an opening formed by the burring process at least in a region located between the first position and the second position where the metal foils are in close contact with each other, or at least in a region adjacent to the first position and the second position where the metal foils are in close contact with each other; a step of joining the electrode tab and the current collector and then housing the electrode body and the current collector in a case body; and sealing the case body housing the electrode body and the current collector with a sealing plate.

6. A step of producing an electrode body including an electrode tab having a laminated structure of metal foil; placing a current collector on the electrode tab; a step of performing a burring process on the electrode tab at a first position and a second position spaced apart from each other along a lamination direction of the metal foil; a step of joining the electrode tab and the current collector by laser welding while leaving an opening formed by the burring process at least in a region located between the first position and the second position where the metal foils are in close contact with each other, or at least in a region adjacent to the first position and the second position where the metal foils are in close contact with each other; a step of joining the electrode tab and the current collector and then housing the electrode body and the current collector in a case body; and sealing the case body accommodating the electrode body and the current collector with a sealing plate, a region where the laser welding is performed is separated from a region where the burring is performed on the electrode tab and the current collector when viewed from a lamination direction of the metal foil.

7. The method for manufacturing a battery cell according to claim 5 or 6, wherein the burring is performed to a depth of 50% or more of a total thickness of the electrode tab.

8. The method for manufacturing a battery cell according to claim 5 , wherein the burring is performed so that the burring width becomes narrower toward the tip.

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