JP7546629B2 - Battery cell and manufacturing method thereof - Google Patents

Description

This technology relates to battery cells and manufacturing methods thereof.

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 that a laser irradiation device is moved across the multiple holes.

JP 2019-207767 A

When forming a laser weld to join the electrode tab and the current collector, there is a possibility that poor welding such as voids or spatters may occur in the laser weld. For this reason, there is room to form a good laser weld for joining the electrode tab and the current collector. In addition, there is a demand to reduce the joining area between the electrode tab and the current collector in order to reduce the size of the battery cell, etc.

This technology has been developed to solve the above problems, and aims to provide a battery cell and a manufacturing method thereof that can reduce the bonding area between the electrode tab and the current collector while forming a good laser weld.

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 is formed on the electrode tab along a lamination direction of the metal foil,
The burring process portion has a depth of 70% or more of the total thickness of the electrode tab,
a laser weld is formed to join the electrode tab and the current collector;
The laser welded portion is formed in an area 0.5 mm to 5 mm outward from the outline of the burring processed portion when viewed from the stacking direction, and is formed so as to sandwich at least the burring processed portion from both sides.
[2]
The battery cell according to [1], wherein the laser welded portion is formed so as to surround substantially the entire periphery of the burred portion when viewed from the stacking direction.
[3]
The battery cell according to claim 1, wherein the laser welded portion has a circular shape when viewed from the stacking direction.
[4]
The battery cell according to claim 1, wherein the laser welded portion has a spiral shape when viewed from the stacking direction.
[5]
The battery cell according to claim 1, wherein the laser welded portion has a polygonal shape when viewed from the stacking direction.
[6]
The battery cell according to claim 1, wherein the laser welded portion is provided radially from the burring processed portion as a center when viewed from the stacking direction.
[7]
The battery cell according to claim 1, wherein the laser welds are arranged in a circular arc shape when viewed from the stacking direction.
[8]
The battery cell according to claim 1, wherein the laser welded portions are arranged in parallel and linear fashion on either side of the burring process portion when viewed from the stacking direction.
[9]
The battery cell according to any one of [1] to [8], wherein the burring processed portion penetrates the electrode tab in the stacking direction.

The present technology provides the following method for manufacturing a battery cell.
[10]
A step of preparing 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 subjecting the electrode tab to a burring process to form a burred portion having a depth of 70% or more of a total thickness of the electrode tab along a lamination direction of the metal foil;
a step of joining the electrode tab and the current collector by performing laser welding so as to sandwich at least the burred portion from both sides in a region of 0.5 mm to 5 mm outward from an outline of the burred portion as viewed from 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.
[11]
The method for manufacturing a battery cell according to [10], wherein the laser welding is performed so as to surround substantially the entire periphery of the burred portion when viewed from the stacking direction.
[12]
The method for manufacturing a battery cell according to [10] or [11], wherein the laser welding is performed in a circular shape when viewed from the stacking direction.
[13]
The method for manufacturing a battery cell according to [10] or [11], wherein the laser welding is performed in a spiral shape when viewed from the stacking direction.
[14]
The method for manufacturing a battery cell according to [10] or [11], wherein the laser welding is performed in a polygonal shape when viewed from the stacking direction.
[15]
The method for manufacturing a battery cell according to [10] or [11], wherein the laser welding is performed in a plurality of radial directions from the burring processed portion as a center when viewed from the stacking direction.
[16]
The method for manufacturing a battery cell according to [10] or [11], wherein the laser welding is performed in a plurality of arc shapes when viewed from the stacking direction.
[17]
The method for manufacturing a battery cell according to [10] or [11], wherein the laser welding is performed in a plurality of parallel and linear directions so as to sandwich the burring processed portion when viewed from the stacking direction.
[18]
The method for manufacturing a battery cell according to any one of [10] to [17], wherein the burring is performed until the electrode tab is penetrated in the stacking direction.

According to this technology, by providing laser welds to sandwich at least the burred portion from both sides in an area 0.5 mm to 5 mm from the outline of the burred portion, it is possible to ensure a laser weld that bonds the electrode tab and the current collector well. This eliminates the need to process a large number of burred portions to form a good laser weld. As a result, it is possible to reduce the bonding area between the electrode tab and the current collector, which is formed by the burred portion and the laser weld, compared to when laser welds are formed between multiple burred portions, while forming a good laser weld between the electrode tab and the current collector.

1 is a perspective view showing a configuration of a battery cell according to an embodiment of the present technology; 1 is an exploded perspective view showing a configuration of a battery cell according to an embodiment of the present technology; 1 is a perspective view showing a configuration of an electrode body according to an embodiment of the present technology; 1 is a schematic diagram showing a joint portion of a battery cell according to an embodiment of the present technology; 5 is a cross-sectional view of the joint shown in FIG. 4 as viewed from the direction of the arrows VV. 4 is a cross-sectional view showing a configuration of a burring processed portion in an electrode tab. FIG. 1 is a cross-sectional view showing the periphery of a burred portion in an electrode tab according to an embodiment of the present technology; 10 is a schematic diagram showing the periphery of the outline of a burred portion of an electrode tab; FIG. 1 is a flow diagram showing a method for manufacturing a battery cell according to an embodiment of the present technology. FIG. 4 is a perspective view showing a state in which a current collector is disposed on an electrode body. 11 is a cross-sectional view showing a state in which a burring processed portion is formed on an electrode tab. FIG. 11 is a cross-sectional view showing a state after a burring processed portion is formed on the electrode tab. FIG. FIG. 13 is a perspective view showing a state in which a laser is irradiated onto an electrode tab. FIG. 4 is a perspective view showing a state in which an electrode body is inserted into a case main body. 13 is a schematic diagram showing a joining area between an electrode tab and a current collector according to a comparative example. FIG. 11 is a schematic diagram showing a joint portion of a battery cell according to a first modified example. FIG. 13 is a schematic diagram showing a joint portion of a battery cell according to a second modified example. FIG. 13 is a schematic diagram showing a joint portion of a battery cell according to a third modified example. FIG. 13 is a schematic diagram showing a joint portion of a battery cell according to a fourth modified example. FIG. 13 is a schematic diagram showing a joint portion of a battery cell according to a fifth modified example. FIG. 13 is a schematic diagram showing a joint portion of a battery cell according to a sixth modified example. FIG. 13 is a schematic diagram showing a joint portion of a battery cell according to a seventh modified example. FIG. FIG. 23 is a schematic diagram showing a joint portion of a battery cell according to an eighth modified example.

The following describes an embodiment of the present technology. Note that the same or corresponding parts are given the same reference symbols, and their descriptions may not be repeated.

In the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present technology is not necessarily limited to those numbers, amounts, etc., unless otherwise specified. In addition, in the embodiments described below, 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 embodiments.

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

In addition, when geometric terms and terms expressing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along," 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 the relative positional relationship in one state, and the relative positional relationship 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).

In this specification, "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, "electrode" may collectively refer to positive and negative electrodes.

In this specification, "battery cells" are not necessarily limited to rectangular ones, but may also include cells of other shapes, such as cylindrical ones.

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

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.

Figure 1 is a perspective view showing the configuration of a battery cell according to one embodiment of the present technology. As shown in Figure 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.

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 spaced apart from each other in the X direction.

The case 120 has a rectangular parallelepiped shape and forms the external appearance of the battery cell 100. The case 120 includes a case body 120A having an opening, 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.

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.

The upper surface 121 is a plane perpendicular to the Z direction. The electrode terminal 110 is disposed on the upper surface 121. The lower surface 122 faces the upper surface 121 along the Z direction.

The first side 123 and the second side 124 each consist of a plane perpendicular to the Y direction. The first side 123 and the second side 124 each have the largest area among the multiple side surfaces of the case 120. When viewed from the Y direction, the first side 123 and the second side 124 each have a rectangular shape with the X direction as the long side and the Z direction as the short side. 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 123 and the second side surface 124 at their ends in the X direction.

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, 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.

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

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

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 negative electrode current collector 142 is connected to the negative electrode terminal 112.

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.

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 body 120A and the electrode body 130, and holds the electrode body 130 while insulating the case 120 and the electrode body 130.

Figure 3 is a perspective view showing the configuration of an electrode body according to one embodiment of the present technology. As shown in Figure 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 multiple electrode bodies are housed in the case 120 may also be used. In addition, the electrode body 130 is not limited to a wound type, and may be a layered type (stack type).

The electrode body 130 includes a positive electrode, a negative electrode, and a separator. The substrate constituting the positive electrode is, for example, an aluminum alloy foil. The substrate constituting the negative electrode is, for example, a copper alloy foil.

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

The positive electrode tab 132, 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 positive electrode strip sheet that extends upward in the Z direction so as to be stacked. As a result, the positive electrode tab 132 has a laminated structure of metal foil. The positive electrode tab 132 is formed by stacking, for example, 50 layers of metal foil. The negative electrode tab 133 is also formed from a part of the negative electrode strip sheet, like the positive electrode tab 132.

The positive electrode tab 132 and the negative electrode tab 133 are arranged on the sealing plate 120B side of the electrode body 130 in the Z direction, but 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 around which the electrode body is wound is aligned with the X direction.

Next, the structure of the joint between the electrode tab 131 and the current collector 140 will be described. Note that in the following explanation, the joint 1A between the positive electrode tab 132 and the positive electrode current collector 141 will be described, but the same structure as that of the joint 1A can also be applied to the joint 1B between the negative electrode tab 133 and the negative electrode current collector 142.

Figure 4 is a schematic diagram showing a joint of a battery cell according to one embodiment of the present technology. Figure 5 is a cross-sectional view of the joint in Figure 4 as viewed from the direction of the V-V line arrow. Figure 6 is a cross-sectional view showing the configuration of a burred part in an electrode tab. Figure 7 is a cross-sectional view showing the periphery of a burred part in an electrode tab according to one embodiment of the present technology. Figure 8 is a schematic diagram showing the periphery of the outline of a burred part in an electrode tab.

As shown in Figures 4 to 8, the joint 1A includes a burring processed portion 10 and a laser welded portion 20.

The burring processing portion 10 is formed on the positive electrode tab 132 and the positive electrode current collector 141 in a state where the positive electrode tab 132 and the positive electrode current collector 141 are stacked. The burring processing portion 10 is formed along the stacking direction of the metal foil that constitutes the positive electrode tab 132. In this embodiment, the burring processing portion 10 has a regular square pyramid shape when viewed from the stacking direction.

The width of the burred portion 10 in the direction perpendicular to the stacking direction becomes narrower as it approaches the positive electrode current collector 141. In other words, the burred portion 10 has a tapered shape.

As shown in FIG. 6, the burring processing portion 10 is configured with a depth D of 70% or more of the total thickness of the positive electrode tab 132 in the stacking direction. When configured with 50 layers of metal foil, it is desirable to configure with a depth of 90% or more of the total thickness of the positive electrode tab 132. This allows the metal foil of the positive electrode tab 132 to be sufficiently adhered to each other. In this embodiment, the burring processing portion 10 penetrates the positive electrode tab 132 in the stacking direction. The depth D is the thickness of the positive electrode tab 132 in the stacking direction. Note that the burring processing portion 10 does not have to penetrate the positive electrode tab 132.

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 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 collector 141 and the negative electrode collector 142, and gaps may 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 (drilling) instead of compression, and therefore a tightly adhered structure between the metal foils can be obtained with a relatively small load compared to compression.

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

The burring processing portion 10 is defined by a vertex 11 and an outline 12. Note that the vertex 11 and the outline 12 may be real or may be virtually defined.

The apex 11 is determined by the processed shape. The apex 11 is the tip of the burred part 10. As shown in Figures 6 and 7, in this embodiment, the burred part 10 penetrates the electrode tab 131, so an imaginary line is drawn from the frustum part of the burred part 10 to the current collector side, and the intersection of the imaginary lines is determined as the apex 11.

The outline 12 is located on the surface 134 of the positive electrode tab 132 opposite to the positive electrode current collector 141. As shown in FIG. 4 and FIG. 6, when the burring processing part 10 is shown in a schematic manner, the outline 12 corresponds to the edge of the processing mark of the burring processing part 10 on the surface 134 of the positive electrode tab 132. As shown in FIG. 7 and FIG. 8, in the burring processing part 10 of this embodiment, the metal foil of the positive electrode tab 132 deforms toward the tip part of the burring processing part 10 during burring processing, so that the boundary between the conical shape of the burring processing part 10 and the surface 134 is curved. In this case, as shown in FIG. 8, the outline 12 is virtually defined by continuously connecting the intersection points of the planar straight line 16 along the surface 134 and the extension line 17 of the conical shape of the burring processing part 10 in the circumferential direction.

As shown in Figures 4 and 5, the positive electrode tab 132 has a flexed portion 33. The flexed portion 33 is a portion where the metal foil is flexed toward the current collector 140 side of the electrode tab 131. The flexed portion 33 is formed by processing the burring processing portion 10, which spreads the metal foil in a direction perpendicular to the stacking direction, with the burring processing portion 10 as the center. The flexed portion 33 has a gap between the stacked metal foils.

As shown in FIG. 7, in this embodiment, the flexure 33 is aligned with the burring processing portion 10 in the stacking direction and bulges toward the positive electrode current collector 141. The flexure 33 bulges to a height H1 from a position that forms a substantially flat surface around the electrode tab 131. The height H1 of the flexure 33 in this embodiment is, for example, 0.10 mm.

The area around the flexure 33 in the direction perpendicular to the stacking direction forms a substantially flat surface. The area around the flexure 33 is an area where there are no gaps between the stacked metal foils or where the gaps are minimized, resulting in the metal foils being in close contact with each other.

The laser welded portion 20 joins the positive electrode tab 132 and the positive electrode current collector 141. The laser welded portion 20 is formed in an area 0.5 mm (L1) to 5 mm (L2) outward from the outline 12 of the burred portion 10 when viewed from the stacking direction.

The position 0.5 mm (L1) outward from the outline 12 is the outermost position of the bending portion 33. Therefore, by forming the laser welded portion 20 at a position 0.5 mm (L1) or more outward from the outline 12, it is possible to avoid the position where the metal foil in the electrode tab 131 bends and weld the area where the metal foil is in close contact. This makes it possible to suppress welding defects such as voids or spatters during laser welding.

The position 5 mm (L2) outward from the outline 12 is a position where the metal foil is densely packed, and where a good laser weld 20 can be obtained with a small joint area. Therefore, if the laser weld 20 is formed at a position 5 mm (L2) or less outward from the outline 12, the electrode tab 131 and the current collector 140 can be laser welded well and joined with a small joint area.

The laser welded portion 20 is formed so as to sandwich at least the burred portion 10 from both sides. Specifically, the laser welded portion 20 has a circular shape when viewed from the stacking direction and is formed so as to surround substantially the entire circumference of the burred portion 10. The trajectory of the laser when forming the laser welded portion 20 is formed in a circular shape, for example, at a position 1 mm outward from the outline 12, taking into account the laser diameter.

As shown in Figures 4 and 5, the positive electrode tab 132 and the positive electrode current collector 141 are joined within the range of the joining area 4 formed by the burring processing portion 10 and the laser welded portion 20 at the joint 1A.

The following describes a method for manufacturing a battery cell according to an embodiment of the present technology. FIG. 9 is a flow diagram showing a method for manufacturing a battery cell according to an embodiment of the present technology. FIG. 10 is a perspective view showing a state in which a collector is placed on an electrode body. FIG. 11 is a cross-sectional view showing a state in which a burred portion is formed on an electrode tab. FIG. 12 is a cross-sectional view showing a state after a burred portion is formed on an electrode tab. FIG. 13 is a perspective view showing a state in which a laser is irradiated on an electrode tab. FIG. 14 is a perspective view showing a state in which an electrode body is inserted into a case body. In FIG. 14, the case 120 is shown in a see-through manner to facilitate understanding of the invention. In FIG. 11 and FIG. 12, a case in which burring is performed on a positive electrode tab 132 is shown, but a similar process can also be applied to a negative electrode tab 133.

In a method for manufacturing a battery cell 100 according to an embodiment of the present technology, first, as shown in Figs. 9 and 10, an electrode body 130 including an electrode tab 131 having a laminated structure of metal foil is produced (step S10). Next, a current collector 140 is placed on the electrode tab 131 (step S21).

Next, the electrode tab 131 is subjected to burring processing to form a burred portion 10 having a depth of 70% or more of the total thickness of the electrode tab 131 along the lamination direction of the metal foil (step S22). The burring processing is performed with the burring pin 2 to form a quadrangular pyramid shape when viewed from the lamination direction. The burring processing is performed until it penetrates the electrode tab 131 in the lamination direction. Since the tip of the burring pin 2 is sharp, the burring pin 2 can be easily pulled out of the positive electrode tab 132 after processing.

Next, as shown in Figures 4, 5, 9, and 13, in an area 0.5 mm (L1) to 5 mm (L2) outward from the outline 12 of the burred portion 10 when viewed from the stacking direction, laser welding is performed to sandwich at least the burred portion 10 from both sides to join the electrode tab 131 and the current collector 140 (step S23).

Laser welding is performed so as to surround substantially the entire circumference of the burred portion 10 when viewed from the stacking direction. Specifically, laser welding is performed in a circular shape when viewed from the stacking direction. The diameter of the laser beam that forms the laser welded portion 20 and the number of times it is irradiated can be changed as appropriate.

Next, as shown in Figs. 9 and 14, 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-mentioned manufacturing process, the battery cell 100 shown in Fig. 1 is manufactured.

Here, we will explain the bonding area between the electrode tab and the current collector of the battery cell according to the comparative example and the present embodiment. Figure 15 is a schematic diagram showing the bonding area between the electrode tab and the current collector according to the comparative example.

As shown in FIG. 15, in the joint 9A of the battery cell according to the comparative example, a laser weld 91 is formed between each of the multiple burring processed parts 90. The laser weld 91 is formed linearly in the horizontal direction in the figure. The laser weld 91 is formed in the part of the metal foil that is in close contact. In the joint area 5 defined by the burring processed parts 90 and the laser weld 91, the electrode tab and the current collector are joined.

On the other hand, as shown in FIG. 4, in the joining of the electrode tab and the current collector in a battery cell according to one embodiment of the present technology, a laser welded portion 20 is formed so as to surround the periphery of the burred portion 10 in a circular shape. In the joining area 4 defined by the burred portion 10 and the laser welded portion 20, the electrode tab 131 and the current collector 140 are joined.

In this embodiment, the laser welded portion 20 is formed by sandwiching the burred portion 10 from at least both sides, so that the area of the laser welded portion 20 can be secured by one burred portion 10. Therefore, the number of burred portions 10 processed can be reduced to one. As a result, the joining area 4 in this embodiment can be reduced in size compared to the joining area 5 in the comparative example. This allows the battery cell 100 to be made smaller.

The number of burring processing sections 10 provided on one electrode tab 131 is preferably one, but is not limited to this. The number of burring processing sections 10 provided on one electrode tab 131 may be multiple to ensure the necessary strength according to the specifications of the battery cell 100.

In the battery cell 100 and its manufacturing method according to one embodiment of the present technology, the laser welded portion 20 is provided so as to sandwich at least the burred portion 10 from both sides in an area 0.5 mm (L1) to 5 mm (L2) from the outline 12 of the burred portion 10, thereby ensuring a laser welded portion 20 that bonds well between the electrode tab 131 and the current collector 140. This does not require a large number of burred portions 10 to be processed in order to form a good laser welded portion 20. As a result, it is possible to reduce the bonding area between the electrode tab 131 and the current collector 140, which is formed by the burred portion 10 and the laser welded portion 20, compared to the case where a laser welded portion is formed between a plurality of burred portions, while forming a good laser welded portion 20 between the electrode tab 131 and the current collector 140.

In the battery cell 100 and its manufacturing method according to one embodiment of the present technology, the laser welded portion 20 is provided so as to surround substantially the entire circumference of the burred portion 10, making it easier to ensure the laser welded portion 20 around the burred portion 10.

In the battery cell 100 and manufacturing method thereof according to one embodiment of the present technology, the laser welded portion 20 is formed in a circular shape, so that the burring processed portion 10 can be surrounded by a short distance, thereby reducing the size of the joint area 4.

In the battery cell 100 and its manufacturing method according to one embodiment of the present technology, by forming the burring processed portion 10, the laser welded portion 20 can be formed with a simple configuration without pressing the electrode tab 131 from the stacking direction of the metal foil during laser welding.

In the battery cell 100 and its manufacturing method according to one embodiment of the present technology, the metal foil of the electrode tab 131 is pierced and burred to facilitate adhesion between the metal foils.

Below, a battery cell and a manufacturing method thereof according to a modified example of an embodiment of the present technology will be described. The battery cell and the manufacturing method thereof according to this modified example differ in the configuration of the joints from the battery cell 100 and the manufacturing method thereof according to an embodiment of the present technology, so the description of the configuration that is similar to the battery cell 100 and the manufacturing method thereof according to an embodiment of the present technology will not be repeated. Note that for the second to eighth modified examples, in order to facilitate understanding of the invention, only the trajectory of the laser welding is shown for the laser welded parts.

Figure 16 is a schematic diagram showing a joint of a battery cell according to the first modified example. As shown in Figure 16, the burring process portion 10C in the joint 1C according to the first modified example is cone-shaped. Even if the burring process portion 10C is cone-shaped, the configuration of the laser welded portion 20 in one embodiment can be applied.

Figure 17 is a schematic diagram showing a joint of a battery cell according to the second modified example. As shown in Figure 17, the laser welding at the joint 1D according to the second modified example is performed in a spiral shape when viewed from the stacking direction. As a result, the laser welded portion 20D has a spiral shape when viewed from the stacking direction.

In the battery cell and its manufacturing method according to the second modification, the laser welded portion 20D is formed into a spiral shape, thereby increasing the welded area of the laser welded portion 20D. This allows the electrode tab and the current collector to be firmly joined.

Figure 18 is a schematic diagram showing a joint of a battery cell according to a third modified example. Figure 19 is a schematic diagram showing a joint of a battery cell according to a fourth modified example. Figure 20 is a schematic diagram showing a joint of a battery cell according to a fifth modified example. The laser welding according to the third, fourth, and fifth modified examples is performed in a polygonal shape when viewed from the stacking direction. As a result, the laser weld has a polygonal shape.

Specifically, as shown in FIG. 18, the laser welding at the joint 1E according to the third modified example is performed in a triangular shape when viewed from the stacking direction. As a result, the laser welded part 20E has a triangular shape when viewed from the stacking direction. As shown in FIG. 19, the laser welding at the joint 1F according to the fourth modified example is performed in a rectangular shape when viewed from the stacking direction. As a result, the laser welded part 20F has a rectangular shape when viewed from the stacking direction. As shown in FIG. 20, the laser welding at the joint 1G according to the fifth modified example is performed in an octagonal shape. As a result, the laser welded part 20G has an octagonal shape when viewed from the stacking direction.

In the battery cells and manufacturing methods thereof according to the third, fourth and fifth modified examples, the laser welded portions 20E, 20F, and 20G can be formed over a short distance to match the shape of the burring processed portion 10.

Figure 21 is a schematic diagram showing a joint of a battery cell according to the sixth modified example. As shown in Figure 21, the laser welds in the joint 1H according to the sixth modified example are performed in multiple radial directions with the burring processed portion 10 at the center when viewed from the stacking direction. As a result, multiple laser welds 20H are provided radially with the burring processed portion 10 at the center.

In the battery cell and its manufacturing method according to the sixth modified example, the laser welded portion 20H is formed radially, so that the area of the laser welded portion 20H can be reduced while surrounding almost the entire circumference of the burring processing portion 10.

Figure 22 is a schematic diagram showing a joint of a battery cell according to the seventh modified example. As shown in Figure 22, the laser welds in the joint 1J according to the seventh modified example are applied in multiple arcs when viewed from the stacking direction. As a result, multiple laser welds 20J are provided in an arc shape when viewed from the stacking direction.

In the battery cell and its manufacturing method according to the seventh modified example, multiple laser welds 20J are formed in an arc shape, making it possible to enclose the burring processing portion 10 while reducing the area of the laser welds 20J.

Figure 23 is a schematic diagram showing a joint of a battery cell according to the eighth modified example. As shown in Figure 23, the laser welds in the joint 1K according to the eighth modified example are applied in a parallel and linear manner to sandwich the burred portion 10 when viewed from the stacking direction. As a result, the laser welds 20K are provided in a parallel and linear manner to sandwich the burred portion 10 when viewed from the stacking direction.

In the battery cell and its manufacturing method according to the eighth modified example, the laser welds 20K are formed in straight lines parallel to each other, making it possible to surround the burring processing portion 10 while keeping the area of the laser welds 20K as small as possible.

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

1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J, 1K, 9A joint, 2 burring pin, 4, 5 joint area, 10, 10C, 90 burring processing part, 11 apex, 12 outline line, 16 plane straight line, 17 extension line, 20, 20D, 20E, 20F, 20G, 20H, 20J, 20K, 91 laser welded part, 33 bending part, 100 battery cell, 110 electrode terminal, 111 positive electrode terminal, 112 negative electrode terminal, 120 case, 120A case main body, 120B sealing plate, 121 upper surface, 122 lower surface, 123 first side, 124 second side, 125 third side, 130 electrode body, 131 electrode tab, 132 Positive electrode tab, 133 negative electrode tab, 134 surface, 140 current collector, 141 positive electrode current collector, 142 negative electrode current collector, 150 electrode body holder.

Claims (18)

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 is formed on the electrode tab along a lamination direction of the metal foil,
The burring process portion has a depth of 70% or more of the total thickness of the electrode tab,
a laser weld is formed to join the electrode tab and the current collector;
The laser welded portion is formed in an area 0.5 mm to 5 mm outward from the outline of the burring processed portion when viewed from the stacking direction, and is formed so as to sandwich at least the burring processed portion from both sides. The battery cell according to claim 1, wherein the laser welded portion is formed so as to surround substantially the entire circumference of the burred portion when viewed from the stacking direction. The battery cell according to claim 1 or 2, wherein the laser welded portion has a circular shape when viewed from the stacking direction. The battery cell according to claim 1 or 2, wherein the laser welded portion has a spiral shape when viewed from the stacking direction. The battery cell according to claim 1 or 2, wherein the laser welded portion has a polygonal shape when viewed from the stacking direction. The battery cell according to claim 1 or 2, wherein the laser welded portions are arranged radially from the burring processing portion as a center when viewed from the stacking direction. The battery cell according to claim 1 or 2, wherein the laser welds are arranged in a circular arc shape when viewed from the stacking direction. The battery cell according to claim 1 or 2, wherein the laser welded portions are arranged in parallel and linear fashion so as to sandwich the burring processed portion when viewed from the stacking direction. The battery cell according to claim 1 or 2, wherein the burring process portion penetrates the electrode tab in the stacking direction. A step of preparing 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 subjecting the electrode tab to a burring process to form a burred portion having a depth of 70% or more of a total thickness of the electrode tab along a lamination direction of the metal foil;
a step of joining the electrode tab and the current collector by performing laser welding so as to sandwich at least the burred portion from both sides in a region of 0.5 mm to 5 mm outward from an outline of the burred portion as viewed from 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. The method for manufacturing a battery cell according to claim 10, wherein the laser welding is performed so as to surround substantially the entire circumference of the burred portion when viewed from the stacking direction. The method for manufacturing a battery cell according to claim 10 or 11, wherein the laser welding is performed in a circular shape when viewed from the stacking direction. The method for manufacturing a battery cell according to claim 10 or 11, wherein the laser welding is performed in a spiral shape when viewed from the stacking direction. The method for manufacturing a battery cell according to claim 10 or 11, wherein the laser welding is performed in a polygonal shape when viewed from the stacking direction. The method for manufacturing a battery cell according to claim 10 or 11, wherein the laser welding is performed in multiple radial directions from the burring processing portion as a center when viewed from the stacking direction. The method for manufacturing a battery cell according to claim 10 or 11, wherein the laser welding is performed in a circular arc shape when viewed from the stacking direction. The method for manufacturing a battery cell according to claim 10 or 11, wherein the laser welding is performed in a plurality of parallel and linear directions so as to sandwich the burring processed portion when viewed from the stacking direction. The method for manufacturing a battery cell according to claim 10 or 11, wherein the burring is performed until the electrode tabs are penetrated in the stacking direction.

Images