Battery cell and manufacturing method thereof

Abstract

To form a good laser weld portion for joining an electrode tab and a current collector.SOLUTION: An electrode body 130 is housed in a case 120 and has an electrode tab 131. A current collector 140 is joined to the electrode tab 131. The electrode tab 131 has a laminated structure of a metal foil. A burring processing portion 10 that becomes narrower in the direction orthogonal to the lamination direction as it goes from the current collector 140 to the electrode tab 131 is formed on at least the current collector 140 of the electrode tab 131 and the current collector 140. A laser welding portion 20 for joining the electrode tab 131 and the current collector 140 is formed on the electrode tab 131 side of the electrode tabs 131 and the current collector 140 that are arranged in the stacking direction.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] JP 2019-207767 A (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] When forming a laser weld to join the electrode tab and the current collector, there is a possibility that welding defects such as voids or spatters may occur in the laser weld, so there is room for forming a good laser weld for joining the electrode tab and the current collector.

[0007] The present technology has been made to solve the above-mentioned problems, and has an object to provide a battery cell and a manufacturing method thereof that are capable of forming good laser welds for joining electrode tabs and current collectors. [Means for solving the problem]

[0008] The present technology provides the following battery cell. [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 burring processed portion having a narrower width in a direction perpendicular to the stacking direction from the current collector toward the electrode tab is formed on at least the current collector among the electrode tab and the current collector along a stacking direction of the metal foil, a laser welded portion that joins the electrode tab and the current collector is formed on the electrode tab side of the electrode tabs and the current collectors that are aligned in the stacking direction. [2] the burring processed portion has an outline defined on a surface of the current collector opposite to the electrode tab, The battery cell according to [1], wherein the laser welded portion is formed at least over the entire area inside the outline when viewed from the stacking direction. [3] The battery cell described in [2], wherein the laser welded portion is formed in the entire area inside the outline and in an area no larger than 5 mm outside the outline when viewed from the stacking direction. [4] The battery cell according to any one of [1] to [3], wherein the burred portion of the electrode tab has a depth of 70% or more of a total thickness of the electrode tab. [5] the electrode tab has a first region that protrudes from an apex of the burred portion toward an opposite side to the current collector, and a second region that is located around the first region and forms a substantially flat surface, The battery cell according to any one of [1] to [4], wherein the laser welded portion is located at least in the second region. [6] The battery cell according to any one of [1] to [5], wherein the burring processing portion has a substantially conical shape. [7] The battery cell according to any one of [1] to [5], wherein the burring processed portion has a substantially regular square pyramid shape. [8] The battery cell according to any one of [1] to [7], wherein the electrode tab and the current collector constitute a part of a negative electrode in the electrode assembly.

[0009] The present technology provides the following method for manufacturing a battery cell. [9] 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 and the current collector from the current collector side of the electrode tab and the current collector arranged in a lamination direction of the metal foil; a step of performing laser welding between the electrode tab and the current collector from the electrode tab side among the electrode tabs and the current collectors arranged in the stacking direction; a step of 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.

[10] The burring process defines an outline on a surface of the current collector opposite to the electrode tab, The method for manufacturing a battery cell according to [9], wherein the laser welding is performed on at least the entire area inside the outline when viewed from the stacking direction.

[11] The method for manufacturing a battery cell according to

[10] , wherein the laser welding is performed in an area inside the outline and within 5 mm outside the outline when viewed from the stacking direction.

[12] The method for manufacturing a battery cell according to any one of [9] to

[11] , wherein the burring process on the electrode tab is performed to a depth of 70% or more of a total thickness of the electrode tab.

[13] The electrode tab is formed with a first region protruding from an apex of the burring to a side opposite to the current collector, and a second region positioned around the first region and constituting a substantially flat surface, The method for manufacturing a battery cell according to any one of [9] to

[12] , wherein the laser welding is performed on at least the second region.

[14] The method for manufacturing a battery cell according to any one of [9] to

[13] , wherein the burring is performed in a substantially conical shape.

[15] The method for manufacturing a battery cell according to any one of [9] to

[13] , wherein the burring is performed to form a substantially regular square pyramid shape.

[16] The method for manufacturing a battery cell according to any one of [9] to

[15] , wherein the electrode tab and the current collector constitute a part of a negative electrode in the electrode assembly. Effect of the Invention

[0010] According to this technology, by performing burring from the current collector side toward the electrode tab, a portion of the electrode tab that is easily deformed by the burring can be located on the surface of the electrode tab opposite the current collector. This allows the deformation of the metal foil of the electrode tab to be visually confirmed and the state of adhesion of the metal foil due to the deformation to be confirmed, so that laser welding can be performed from the electrode tab side, targeting the area where the laminated metal foils are in close contact. As a result, the generation of voids or spatters in the laser welded portion can be suppressed, and a good laser welded portion can be formed. [Brief description of the drawings]

[0011] [Figure 1] 1 is a perspective view showing a configuration of a battery cell according to a first embodiment of the present technology. [Diagram 2] 1 is an exploded perspective view showing a configuration of a battery cell according to a first embodiment of the present technology. [Diagram 3] 1 is a perspective view showing a configuration of an electrode body according to a first embodiment of the present technology. [Figure 4] 1 is a schematic diagram showing a joint of a battery cell according to a first embodiment of the present technology. [Diagram 5] 5 is a cross-sectional view of the joint shown in FIG. 4 as viewed from the direction of the VV line arrow. [Figure 6] 2 is a cross-sectional view showing the periphery of a burred portion in an electrode tab according to a first embodiment of the present technology. [Figure 7] 10 is a schematic diagram showing the periphery of the outline of a burred portion of an electrode tab; FIG. [Figure 8] 4 is a flow diagram showing a method of manufacturing a battery cell according to the first embodiment of the present technology. [Figure 9] FIG. 4 is a perspective view showing a state in which a current collector is disposed on an electrode body. [Figure 10] 11 is a cross-sectional view showing a state in which a burring processed portion is formed on an electrode tab. FIG. [Figure 11] FIG. 13 is a perspective view showing a state in which a laser is irradiated onto an electrode tab. [Figure 12] FIG. 4 is a perspective view showing a state in which a current collector and a sealing plate are connected to each other. [Figure 13]FIG. 4 is a perspective view showing a state in which an electrode body is inserted into a case main body. [Figure 14] 10 is a schematic diagram showing a joint between an electrode tab and a current collector in a battery cell according to a comparative example. FIG. [Figure 15] 11 is a cross-sectional view showing the periphery of a burred portion in an electrode tab according to a second embodiment of the present technology. FIG. [Figure 16] 11 is a top view showing a joint of a battery cell according to embodiment 3 of the present technology. FIG. 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] In the drawings, the direction in which the positive and negative terminals of the battery cells are arranged is the X direction, the direction in which multiple battery cells are stacked is the Y direction, and the height direction of the battery cells is the Z direction.

[0020] (Embodiment 1) Fig. 1 is a perspective view showing a configuration of a battery cell according to embodiment 1 of the present technology. As shown in Fig. 1, the battery cell 100 has a rectangular shape. The battery cell 100 has an electrode terminal 110 and a case 120 (external can). In other words, the battery cell 100 is a rectangular secondary battery cell.

[0021] The electrode terminal 110 is formed on the case 120. The electrode terminal 110 has a positive electrode terminal 111 and a negative electrode terminal 112 aligned along the X direction. The positive electrode terminal 111 and the negative electrode terminal 112 are provided spaced apart from each other in the X direction.

[0022] Case 120 has a rectangular parallelepiped shape and forms the external appearance of battery cell 100. Case 120 includes case body 120A having an opening, and sealing plate 120B that seals the opening of case body 120A. Sealing plate 120B is joined to case body 120A by welding.

[0023] The case 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.

[0024] The upper surface 121 is a plane perpendicular to the Z direction. The electrode terminals 110 are disposed on the upper surface 121. The upper surface 121 in this embodiment corresponds to the sealing plate 120B. The lower surface 122 faces the upper surface 121 in the Z direction.

[0025] Each of the first side surface 123 and the second side surface 124 is a plane perpendicular to the Y 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 case 120. Each of the first side surface 123 and the second side surface 124 has a rectangular shape with the X direction as the longitudinal direction and the Z direction as the lateral direction when viewed from the Y direction. The two third side surfaces 125 are aligned in the X direction and face each other. The two third side surfaces 125 connect the first side surface 123 and the second side surface 124 at their ends in the X direction.

[0026] 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 direction face each other. As a result, the positive electrode terminals 111 and the negative electrode terminals 112 are arranged alternately in the Y direction in which the multiple battery cells 100 are stacked.

[0027] Fig. 2 is an exploded perspective view showing the configuration of a battery cell according to embodiment 1 of the present technology. As shown in Fig. 2, in the battery cell 100, the inside of the case 120 contains an electrode assembly 130, a current collector 140, an electrode assembly holder 150, and an electrolyte (not shown).

[0028] The electrode terminal 110 is fixed to the sealing plate 120B via a resin insulating member (not shown). A positive electrode tab 132 and a negative electrode tab 133, which are electrode tabs 131, are formed on the electrode body 130 on the sealing plate 120B side. The current collector 140 is joined to the positive electrode tab 132 and the negative electrode tab 133.

[0029] The current collector 140 includes a positive electrode current collector 141 and a negative electrode current collector 142. The positive electrode current collector 141 is connected to the positive electrode terminal 111. The positive electrode current collector 141 is made of, for example, aluminum or an aluminum alloy. The negative electrode current collector 142 is connected to the negative electrode terminal 112. The negative electrode current collector 142 is made of, for example, copper or a copper alloy. The thickness of the current collector 140 is, for example, 0.8 mm.

[0030] The electrode terminal 110 and the electrode body 130 are electrically connected via the current collector 140. Specifically, the positive electrode tab 132 is joined to the positive electrode current collector 141 at joint 1A. This allows the positive electrode terminal 111 and the positive electrode tab 132 to be electrically connected via the positive electrode current collector 141. The negative electrode tab 133 is joined to the negative electrode current collector 142 at joint 1B. This allows the negative electrode terminal 112 and the negative electrode tab 133 to be electrically connected via the negative electrode current collector 142.

[0031] The electrode body holder 150 is an insulating sheet. The electrode body holder 150 covers the periphery of the electrode body 130. The electrode body holder 150 is positioned between the case main body 120A and the electrode body 130 to hold the electrode body 130 while insulating the case 120 and the electrode body 130.

[0032] Fig. 3 is a perspective view showing a configuration of an electrode body according to the first embodiment of the present technology. As shown in Fig. 3, the electrode body 130 in this embodiment is a wound type. Note that, in this embodiment, one electrode body 130 is housed in the case 120, but a configuration in which a plurality of electrode bodies are housed in the case 120 may also be used. Also, the electrode body 130 is not limited to the wound type, and may be a layered type (stack type).

[0033] The electrode assembly 130 includes a positive electrode, a negative electrode, and a separator. The substrate constituting the positive electrode is, for example, an aluminum foil or an aluminum alloy foil. The substrate constituting the negative electrode is, for example, a copper foil or a copper alloy foil.

[0034] The positive electrode, the negative electrode, and the separator are all strip-shaped sheets. The separator is sandwiched between the positive electrode and the negative electrode. The electrode assembly 130 is formed by winding a laminate of the positive electrode, the negative electrode, and the separator. The electrode assembly 130 may be formed into a flat shape after winding.

[0035] The negative electrode tab 133, which is the electrode tab 131, is formed by winding a laminate of a positive electrode, a negative electrode, and a separator, and arranging the portion of the negative electrode strip sheet that extends upward in the Z direction so as to be stacked. As a result, the negative electrode tab 133 has a laminated structure of metal foil. The negative electrode tab 133 is formed by stacking, for example, 50 layers of metal foil. The thickness of one sheet of metal foil is, for example, 8 μm. The positive electrode tab 132 is also formed from a part of the positive electrode strip sheet like the negative electrode tab 133.

[0036] Although the positive electrode tab 132 and the negative electrode tab 133 are disposed on the sealing plate 120B side of the electrode body 130 in the Z direction, the arrangement of the positive electrode tab 132 and the negative electrode tab 133 is not limited to this. The positive electrode tab and the negative electrode tab may be formed separately on both sides of the electrode body in the X direction. In this case, the axis about which the electrode body is wound is aligned with the X direction.

[0037] Next, a description will be given of the structure of the joint between the electrode tab 131 and the current collector 140. In the following description, the joint 1B between the negative electrode tab 133 and the negative electrode current collector 142 will be described, but the same structure as that of the joint 1B can also be applied to the joint 1A between the positive electrode tab 132 and the positive electrode current collector 141.

[0038] Fig. 4 is a schematic diagram showing a joint of a battery cell according to embodiment 1 of the present technology. Fig. 5 is a cross-sectional view of the joint in Fig. 4 as viewed from the direction of the VV line arrow. Fig. 6 is a cross-sectional view showing the periphery of a burred part in an electrode tab according to embodiment 1 of the present technology. Fig. 7 is a schematic diagram showing the periphery of an outline of a burred part in an electrode tab.

[0039] As shown in FIGS. 4 to 7, the joint 1B includes a burred portion 10 and a laser welded portion 20. As shown in FIG.

[0040] The burring processed portion 10 is formed on at least the current collector 140 out of the electrode tab 131 and the current collector 140. The burring processed portion 10 in this embodiment is formed on the negative electrode current collector 142 in a state in which the negative electrode tab 133 and the negative electrode current collector 142 are overlapped. Note that, in a state before the laser welded portion 20 is formed, the burring processed portion 10 is formed on both the negative electrode tab 133 and the negative electrode current collector 142. The burring processed portion 10 is formed along the lamination direction of the metal foil constituting the negative electrode tab 133.

[0041] The width of the burring process portion 10 in the direction perpendicular to the lamination direction of the metal foil becomes narrower from the negative electrode current collector 142 toward the negative electrode tab 133. That is, the burring process portion 10 has a tapered shape. The burring process portion 10 in the present embodiment has a substantially conical shape. The tip angle of the burring process portion 10 in the present embodiment is, for example, 40°.

[0042] Burrs generated during burring tend to cause the metal foils to adhere to each other, and the laminated structure of the metal foils can be bound together. In contrast, compression processing, in which the laminated structure of the metal foils is compressed to crush the metal foils, makes it difficult to bind the metal foils together, and there is a possibility that gaps will form between the metal foils. In order to reliably avoid gaps between the metal foils, a fairly large compression load is required. In contrast, the battery cell 100 according to this embodiment employs burring (hole punching) instead of compression processing, and therefore a tightly adhered structure between the metal foils can be obtained with a relatively small load compared to compression processing.

[0043] 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.

[0044] The burring processing portion 10 is defined with a vertex 11 and an outline 12. The vertex 11 and the outline 12 may be real or may be virtually defined.

[0045] The apex 11 is defined by the processed shape. The apex 11 is the tip of the burred portion 10. As shown in Fig. 5 and Fig. 6, in this embodiment, after the burred portion 10 is formed, the laser welded portion 20 is formed so as to overlap the burred portion 10 in the lamination direction, so that the apex 11 is defined virtually. The apex 11 is defined by drawing a virtual line from the frustum portion of the burred portion 10 to the tip side, and the intersection of the virtual lines is defined as the apex 11.

[0046] 6, when the laser welded portion 20 is formed, the negative electrode tab 133 or the negative electrode current collector 142 melted by the laser welding may enter the internal space of the burring processed portion 10, causing the laser welded portion 20 to fall toward the negative electrode current collector 142. As a result, with respect to the tab surface 134a on the welded portion aligned with the laser welded portion 20 in the stacking direction among the tab surfaces 134 on the opposite side of the current collector 140 in the electrode tab 131, the apex 11 may be defined above the tab surface 134a on the welded portion.

[0047] 5 to 7, the outline 12 is located on a surface 143 of the negative electrode current collector 142 opposite to the negative electrode tab 133. When the burred portion 10 is shown diagrammatically as shown in FIGS. 4 and 5, the outline 12 corresponds to the edge of the processing mark of the burred portion 10 on the surface 143 of the negative electrode current collector 142.

[0048] 6 and 7, in the burred portion 10 of the present embodiment, the negative electrode current collector 142 is deformed toward the tip portion of the burred portion 10 during burring, so that the boundary between the conical shape of the burred portion 10 and the surface 143 is curved. In this case, as shown in Fig. 7, the outline 12 is virtually defined by continuously connecting the intersections of a planar straight line 16 along the surface 143 and an extension line 17 of the conical shape of the burred portion 10 in the circumferential direction.

[0049] 5, the burred portion 10 of the negative electrode tab 133 has a depth D that is 70% or more of the total thickness T1 of the negative electrode tab 133 in the lamination direction of the metal foil. The depth D of the burred portion 10 is the distance from the end face of the negative electrode tab 133 on the negative electrode current collector 142 side to the apex 11 in the lamination direction of the metal foil. The total thickness T1 of the negative electrode tab 133 is the thickness in the lamination direction after the burred portion 10 and the laser welded portion 20 are processed and at a position where the metal foils are stacked in close contact and are not affected by these processes.

[0050] The surface shape of the negative electrode current collector 142 on the negative electrode tab 133 side may become unclear depending on the degree of burring or laser welding, making it difficult to determine the position of the end face of the negative electrode tab 133 on the negative electrode current collector 142 side in the lamination direction of the metal foil. In this case, the total depth Dt of the burred portion 10 is defined by the distance from the surface 143 of the negative electrode current collector 142 to the apex 11 in the lamination direction of the metal foil. In this case, the depth D of the burred portion 10 may be calculated by subtracting the thickness T2 of the portion of the negative electrode current collector 142 that is not affected by the burring from the total depth Dt of the burred portion 10.

[0051] When the negative electrode tab 133 is composed of 50 layers of metal foil, it is desirable that the depth D of the burring processed portion 10 is configured to be 90% or more of the total thickness T1 of the negative electrode tab 133. This allows the metal foils of the negative electrode tab 133 to be sufficiently adhered to each other.

[0052] The depth D of the burred portion 10 can be measured, for example, by cutting the joint 1B at a cross section passing through the vertex 11 and perpendicular to the lamination direction of the metal foil, and observing the cross section with a metallurgical microscope or the like.

[0053] The laser welded portion 20 joins the negative electrode tab 133 and the negative electrode current collector 142. The laser welded portion 20 is formed so as to join the negative electrode tab 133 and the negative electrode current collector 142 to each other on the negative electrode tab 133 side of the negative electrode tab 133 and the negative electrode current collector 142 which are aligned in the lamination direction of the metal foil.

[0054] 4 and 5, the laser welded portion 20 is formed at least in the entire area inside the outline 12 when viewed from the lamination direction of the metal foil. In this embodiment, the laser welded portion 20 is formed in the entire area inside the outline 12 and in a range of 5 mm (L1) or less outside the outline 12 when viewed from the lamination direction of the metal foil. In this manner, the negative electrode tab 133 and the negative electrode current collector 142 are joined within the range of the joining region 4 formed by the burring processed portion 10 and the laser welded portion 20 in the joint 1B.

[0055] The shape of the laser welded portion 20 is circular when viewed from the lamination direction of the metal foil, but is not limited thereto, and may be an elliptical or rectangular shape, etc. The conical shape of the burred portion 10 also includes a shape in which a conical shape and a cylindrical shape are combined side by side in the lamination direction.

[0056] As shown in FIG. 6, the negative electrode tab 133 has a first region 30 and a second region 31. The first region 30 is formed by processing the burred portion 10. The first region 30 is a region in which gaps are formed between the laminated metal foils due to deformation of the metal foil caused by the burring process. The first region 30 protrudes from the apex 11 of the burred portion 10 to the opposite side to the negative electrode current collector 142.

[0057] The second region 31 is located around the first region 30 in a direction perpendicular to the stacking direction, and forms a substantially flat surface in the direction perpendicular to the stacking direction. The second region 31 is a region in which there is no gap between the stacked metal foils, or the gap is minimized, so that the metal foils are in close contact with each other.

[0058] The laser welded portion 20 is located at least in the second region 31. In this embodiment, the laser welded portion 20 is located in a part of the first region 30 and in the second region 31. When the second region 31 around the first region 30 is laser welded, the heat of the second region 31 is transmitted to the first region 30, and the first region 30 melts, so that the first region 30 may disappear.

[0059] As described above, the negative electrode tab 133 and the negative electrode current collector 142 are joined by the burring processing portion 10 and the laser welding portion 20, so that the negative electrode tab 133 and the negative electrode current collector 142 form part of the negative electrode in the electrode body 130. Copper present in the negative electrode can cause voltage defects in the battery cell 100 if it is present in the battery cell 100 as foreign matter such as sputters. Therefore, if the occurrence of copper sputters in the negative electrode is suppressed, voltage defects in the battery cell 100 are suppressed.

[0060] Hereinafter, a method for manufacturing a battery cell according to the first embodiment of the present technology will be described. FIG. 8 is a flow diagram showing a method for manufacturing a battery cell according to the first embodiment of the present technology. FIG. 9 is a perspective view showing a state in which a current collector is disposed on an electrode body. FIG. 10 is a cross-sectional view showing a state in which a burred portion is formed on an electrode tab. FIG. 11 is a perspective view showing a state in which a laser is irradiated on an electrode tab. FIG. 12 is a perspective view showing a state in which a current collector and a sealing plate are connected. FIG. 13 is a perspective view showing a state in which an electrode body is inserted into a case body. Note that, although FIGS. 10 and 11 show a case in which burring or laser welding is performed on a negative electrode tab 133, a similar process may also be applied to a positive electrode tab 132. In addition, in FIG. 13, a case 120 is shown in a see-through manner in order to facilitate understanding of the invention.

[0061] 8 and 9, the method for manufacturing the battery cell 100 according to this embodiment begins with fabricating an electrode body 130 including an electrode tab 131 having a laminated structure of metal foil (step S10). Next, a current collector 140 is disposed on the electrode tab 131 (step S21).

[0062] 8 and 10, of the negative electrode tabs 133 and the negative electrode current collectors 142 aligned in the lamination direction of the metal foil, burring is performed on the negative electrode tabs 133 and the negative electrode current collectors 142 from the negative electrode current collector 142 side (step S22). The burring is performed by using a burring pin 2 to form a cone shape as viewed from the lamination direction. Since the tip of the burring pin 2 is sharp, the burring pin 2 can be easily pulled out of the negative electrode tab 133 after processing.

[0063] 10, the negative electrode tab 133 has a bending portion 33. The bending portion 33 is a portion where the metal foil is bent and wavy on the side of the negative electrode tab 133 opposite to the negative electrode current collector 142. The bending portion 33 is formed by processing the burring processed portion 10, in which the metal foil is pushed and spread in a direction perpendicular to the stacking direction with the burring processed portion 10 as the center. The bending portion 33 has a gap between the stacked metal foils.

[0064] The region around the flexible portion 33 in the direction perpendicular to the stacking direction forms a substantially flat surface. The region around the flexible portion 33 is a region where there is no gap between the stacked metal foils or where the gap is minimized, so that the metal foils are in close contact with each other.

[0065] 8, 10, and 11, the electrode tab 131 and the current collector 140 are laser-welded from the electrode tab 131 side of the electrode tab 131 and the current collector 140 arranged in the lamination direction of the metal foil (step S23). The diameter of the laser beam of the laser 21 forming the laser welded portion 20 and the number of times of irradiation can be changed as appropriate. Next, as shown in FIG. 12, the current collector 140 and the sealing plate 120B are connected.

[0066] 8 and 13, the electrode body 130 and the current collector 140 are housed in the case body 120A (step S31). Finally, the case body 120A housing the electrode body 130 and the current collector 140 is sealed with the sealing plate 120B (step S32). Through the above-described manufacturing steps, the battery cell 100 shown in FIG. 1 is manufactured.

[0067] Here, the joining of the electrode tab and the current collector of the battery cell according to the comparative example will be described. Fig. 14 is a schematic diagram showing the joining part between the electrode tab and the current collector in the battery cell according to the comparative example. Note that Fig. 14 shows the state in the middle of forming the laser welded part.

[0068] 14, in a joint 9 of a battery cell according to the comparative example, laser welding is performed on a bent portion 93 of an electrode tab 931. A laser weld 90 is formed with the bent portion 93 as a base point.

[0069] When the laser welded portion 90 is formed, gaps are generated between the metal foils of the electrode tab 931 around the bending portion 93. When the electrode tab 931 with the gaps is irradiated with the laser 21, the electrode tab 931 is likely to be welded while drawing in air, etc., and thus spatters 91 or voids 92 are generated. For this reason, poor joining is likely to occur in the joining of the electrode tab 931 and the current collector 940 in the comparative example.

[0070] 10, in the joining of the electrode tab 131 and the current collector 140 in the battery cell 100 according to the first embodiment of the present technology, welding that involves the inclusion of air or the like is suppressed by performing laser welding in a portion other than the bending portion 33 generated by the burring process. Therefore, by suppressing the occurrence of spatter or voids, poor joining between the electrode tab 131 and the current collector 140 is suppressed.

[0071] In the battery cell 100 and its manufacturing method according to the first embodiment of the present technology, by performing burring from the current collector 140 side toward the electrode tab 131, a portion that is easily deformed by the burring can be disposed on the tab surface 134 of the electrode tab 131 on the side opposite the current collector 140. This allows the deformation of the metal foil to be visually confirmed and the state of adhesion of the metal foil due to the deformation to be confirmed, so that laser welding can be performed from the electrode tab 131 side, targeting the area where the laminated metal foils are in close contact. As a result, the generation of voids or spatters in the laser welded portion 20 can be suppressed, and a good laser welded portion 20 can be formed.

[0072] In the battery cell 100 and its manufacturing method according to the first embodiment of the present technology, the laser welded portion 20 is formed at least over the entire area inside the outline 12 of the burred portion 10 when viewed from the lamination direction of the metal foil, thereby making it possible to reduce the joining area between the electrode tab 131 and the current collector 140 while ensuring a minimum laser welding area. As a result, the battery cell 100 can be made smaller.

[0073] In the battery cell 100 and its manufacturing method relating to embodiment 1 of the present technology, when viewed from the stacking direction of the metal foil, the laser welds 20 are formed in the entire area inside the outline 12 of the burring processed portion 10 and in an area of ​​5 mm (L1) or less outside the outline 12. This makes it possible to widen the range of the laser welds 20 compared to a case in which the laser welds 20 are formed only in the entire area inside the outline 12, thereby enabling the electrode tab 131 and the current collector 140 to be firmly joined.

[0074] In the battery cell 100 and its manufacturing method according to the first embodiment of the present technology, the depth D of the burred portion 10 is configured to be 70% or more of the total thickness T1 of the electrode tab 131, thereby making it easier to deform the metal foil of the electrode tab 131. This makes it easier to visually confirm the area of ​​the electrode tab 131 where the metal foil is in close contact after the burring process.

[0075] In the battery cell 100 and its manufacturing method according to the first embodiment of the present technology, by performing burring from the current collector 140 side toward the electrode tab 131, it is possible to visually confirm the first region 30 having gaps between the laminated metal foils on the tab surface 134. This allows the second region 31 where the metal foils are in close contact in the electrode tab 131 to be welded, thereby reducing welding defects between the electrode tab 131 and the current collector 140.

[0076] In the battery cell 100 and its manufacturing method relating to embodiment 1 of the present technology, by making the burring processing portion 10 approximately conical in shape, the processing range of the burring processing portion 10 can be made smaller compared to the case of a burring processing portion having an approximately regular quadrangular pyramid shape having a square outline circumscribing the outline 12, and therefore the deformation of the metal foil of the electrode tab 131 can be reduced, thereby reducing the impact of the burring processing on the electrode tab 131.

[0077] In the battery cell 100 and its manufacturing method according to the first embodiment of the present technology, the burring process is performed from the current collector 140 side toward the electrode tab 131, and laser welding is performed from the electrode tab 131 side, thereby suppressing the generation of foreign matter such as copper sputters in the negative electrode. As a result, voltage defects in the battery cell 100 can be suppressed.

[0078] (Embodiment 2) Hereinafter, a battery cell and a manufacturing method thereof according to embodiment 2 of the present technology will be described. Since the battery cell and the manufacturing method thereof according to embodiment 2 of the present technology have different joint configurations from the battery cell 100 and the manufacturing method thereof according to embodiment 1 of the present technology, the description of the configurations similar to those of the battery cell 100 and the manufacturing method thereof according to embodiment 1 of the present technology will not be repeated.

[0079] Fig. 15 is a cross-sectional view showing the periphery of a burred portion in an electrode tab according to embodiment 2 of the present technology. As shown in Fig. 15, a laser welded portion 20C in a joint 1C according to embodiment 2 is formed in a range not less than the outside of an outline 12C of the burred portion 10C and not more than 5 mm (L2) outside the outline 12C when viewed from the lamination direction of the metal foil of the electrode tab 131. The laser welded portion 20C is formed to avoid a bending portion 33C.

[0080] In the battery cell and its manufacturing method according to the second embodiment of the present technology, by performing burring from the current collector 140 side toward the electrode tab 131, a portion (flexed portion 33C) that is easily deformed by the burring can be disposed on the surface of the electrode tab 131 opposite the current collector 140. This allows the deformation of the metal foil to be visually confirmed and the state of adhesion of the metal foil due to the deformation to be confirmed, so that laser welding can be performed from the electrode tab 131 side, targeting the region where the laminated metal foils are in close contact. As a result, it is possible to form a good laser welded portion 20C by suppressing the generation of voids or spatters in the laser welded portion 20C without melting the flexed portion 33C due to the heat input of the laser welding.

[0081] (Embodiment 3) Hereinafter, a battery cell and a manufacturing method thereof according to embodiment 3 of the present technology will be described. Since the battery cell and the manufacturing method thereof according to embodiment 3 of the present technology have a different configuration of the burring processing part from the battery cell 100 and the manufacturing method thereof according to embodiment 1 of the present technology, the description of the configuration similar to the battery cell 100 and the manufacturing method thereof according to embodiment 1 of the present technology will not be repeated.

[0082] Fig. 16 is a top view showing a joint of a battery cell according to embodiment 3 of the present technology. As shown in Fig. 16, an electrode tab 131D and a current collector 140D included in the battery cell according to embodiment 3 of the present technology are joined at a joint 1D. A burring processed portion 10D at the joint 1D has a substantially square pyramid shape.

[0083] The laser welded portion 20D is formed in the entire area inside the outline 12D and within a range of 5 mm (L3) outside the outline 12D when viewed from the lamination direction of the metal foil of the electrode tab 131D. The electrode tab 131D and the current collector 140 are joined within a joining region 4 formed by the burred portion 10D and the laser welded portion 20D in the joint 1D.

[0084] In the battery cell and manufacturing method thereof according to the third embodiment of the present technology, by forming the burring processing portion 10D into a regular pyramid shape, the processing range of the burring processing portion 10D can be made wider than in the case of a cone-shaped burring processing portion formed by the inscribed circle of the outline 12D of the burring processing portion 10D, and therefore the area where the metal foil is in close contact in the electrode tab 131D can be made wider. As a result, the laser irradiation range in the electrode tab 131D can be easily ensured.

[0085] In the above-described embodiments, only one burring portion is provided for either the positive electrode tab or the negative electrode tab, but the present invention is not limited to this configuration. A plurality of burring portions may be provided for either the positive electrode tab or the negative electrode tab.

[0086] 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]

[0087] 1A, 1B, 1C, 1D, 9 joint, 2 burring pin, 4 joint area, 10, 10C, 10D burring processed area, 11 apex, 12, 12C, 12D outline, 16 plane straight line, 17 extension line, 20, 20C, 20D, 90 laser welded area, 21 laser, 30 first area, 31 second area, 33, 33C, 93 bending area, 91 spatter, 92 void, 100 battery cell, 110 electrode terminal, 111 positive electrode terminal, 112 negative electrode terminal, 120 case, 120A case body, 120B sealing plate, 121 upper surface, 122 lower surface, 123 first side, 124 second side, 125 third side, 130 electrode body, 131, 131D, 931 Electrode tab, 132 positive electrode tab, 133 negative electrode tab, 134 tab surface, 134a tab surface on weld, 140, 140D, 940 current collector, 141 positive electrode current collector, 142 negative electrode current collector, 143 surface, 150 electrode body holder.

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 burring processed portion having a narrower width in a direction perpendicular to the stacking direction from the current collector toward the electrode tab is formed on at least the current collector of the electrode tab and the current collector along a stacking direction of the metal foil, a laser welded portion that joins the electrode tab and the current collector is formed on the electrode tab side of the electrode tabs and the current collectors that are aligned in the stacking direction.

2. the burring processed portion has an outline defined on a surface of the current collector opposite to the electrode tab, The battery cell according to claim 1 , wherein the laser welded portion is formed at least over the entire area inside the outline when viewed in the stacking direction.

3. 3 . The battery cell according to claim 2 , wherein the laser welds are formed in an area on the inside of the outline and within 5 mm outside the outline when viewed from the stacking direction.

4. 4. The battery cell according to claim 1, wherein the burred portion of the electrode tab has a depth of 70% or more of a total thickness of the electrode tab.

5. the electrode tab has a first region that protrudes from an apex of the burred portion toward an opposite side to the current collector, and a second region that is located around the first region and forms a substantially flat surface, The battery cell according to claim 1 or 2, wherein the laser weld is located at least in the second region.

6. The battery cell according to claim 1 or 2, wherein the burring processed portion has a substantially conical shape.

7. The battery cell according to claim 1 or 2, wherein the burred portion has a substantially regular square pyramid shape.

8. The battery cell according to claim 1 , wherein the electrode tab and the current collector form a part of a negative electrode in the electrode assembly.

9. 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 and the current collector from the current collector side of the electrode tab and the current collector arranged in a lamination direction of the metal foil; a step of performing laser welding between the electrode tab and the current collector from the electrode tab side among the electrode tabs and the current collectors arranged in the stacking direction; a step of 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.

10. The burring process defines an outline on a surface of the current collector opposite to the electrode tab, The method for manufacturing a battery cell according to claim 9 , wherein the laser welding is performed on at least the entire area inside the outline when viewed from the stacking direction.

11. The method for manufacturing a battery cell according to claim 10 , wherein the laser welding is performed in an area on the inside of the outline and within 5 mm outside the outline when viewed from the stacking direction.

12. The method for manufacturing a battery cell according to claim 9 , wherein the burring of the electrode tab is performed to a depth of 70% or more of a total thickness of the electrode tab.

13. The electrode tab is formed with a first region protruding from an apex of the burring to a side opposite to the current collector, and a second region positioned around the first region and constituting a substantially flat surface, The method for manufacturing a battery cell according to claim 9 or 10, wherein the laser welding is performed on at least the second region.

14. The method for manufacturing a battery cell according to claim 9 or 10, wherein the burring is performed to form a substantially conical shape.

15. The method for manufacturing a battery cell according to claim 9 or 10, wherein the burring is performed to form a substantially regular quadrangular pyramid shape.

16. The method for manufacturing a battery cell according to claim 9 or 10, wherein the electrode tab and the current collector form a part of a negative electrode in the electrode assembly.

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