KR102736954B1 - Seam welding Structure of battery can and cap and battery cell using the same - Google Patents

Abstract

The present invention relates to a welding structure of a battery can and a cap, and a battery cell using the same. The battery cell comprises a can including a bottom member and a side wall member connected to the bottom member and extending in the axial direction, an electrode assembly accommodated inside the can, and a cap covering an open end provided at one axial end of the side wall member. A terminal connection portion is provided on a radially outer edge of a current collector plate connected to an electrode of the electrode assembly and arranged on the open end side, which extends axially outward and contacts and is electrically connected to an inner surface of the side wall member. The inner surface of the side wall member and the outer surface of the cap are welded in a state where at least a portion of the terminal connection portion is interposed between the inner surface of the side wall member and the outer surface of the cap in the axial direction, thereby forming a weld portion.

Description

{Seam welding structure of battery can and cap and battery cell using the same}

The present invention relates to a welding structure of a battery can and a cap and a battery cell using the same.

The process for manufacturing a battery cell using a cylindrical can includes the steps of deep drawing a metal sheet to form a circular bottom member and a circular tubular side wall member connected thereto, accommodating an electrode assembly therein, and then finishing by covering the open end of the side wall member with a cap.

Meanwhile, at one of the axial ends of the electrode assembly facing the open end, a current collector plate is provided that contacts and is electrically connected to the electrode tab of the electrode assembly. The current collector plate is connected to the cap or the side wall member by welding or the like so that it contacts and is electrically connected to the cap or the side wall member.

Referring to FIG. 15, in a process of welding the current collector plate to the cap or side wall member, the current collector plate must be maintained in a state of close contact with the cap or side wall member. To this end, a jig for close contact between the current collector plate and the cap or the current collector plate and the side wall member is required, and in addition, a mask for exposing the welding area is required.

In order to adhere the collector plate to the cap or side wall member through the mask or jig, a space must be provided inside the can to accommodate the mask or jig. However, this space remains empty after the mask or jig is removed, resulting in a problem in that the internal volume of the can cannot be efficiently utilized. This becomes a factor that hinders the design to increase the energy density per unit volume of the can.

In addition, when closing the open end of the cylindrical can, a process of connecting the current collector plate to the cap or the side wall member and a process of connecting the cap to the side wall member are each performed. This increase in labor is a factor that reduces the production efficiency of cylindrical battery cells and increases the production cost.

Meanwhile, if the welding heat generated when welding the can and cap is transferred to the electrode assembly contained inside the can, there is a risk of deterioration of the separator and deformation or disassembly of the internal structure. Therefore, it is necessary to prevent such welding heat from being transferred to the electrode assembly.

The present invention has been made to solve the above-described problems, and provides a welding structure of a battery can and a cap capable of designing to increase the energy density per unit volume of the can without wasting the internal space of the can when welding a current collector provided on the open end of the can to the can, and a battery cell using the welding structure.

In addition, the present invention aims to provide a welding structure of a battery can and a cap, and a battery cell using the same, which can increase the production efficiency of a cylindrical battery cell and reduce the production cost by integrating the process of welding the current collector to the can and the process of welding the cap to the side wall member into a single welding process.

In addition, the present invention provides a welding structure of a can and a cap, and a battery cell using the same, in which the cap simultaneously functions as a jig for pressing a collector plate, thereby eliminating the need for a separate jig for pressing a collector plate for welding the collector plate.

In addition, the present invention aims to provide a welding structure of a can and a cap, which can minimize damage to an electrode assembly due to heat by allowing heat generated when welding the can and the cap to be discharged through a current collector, and a battery cell using the welding structure.

The technical problems of the present invention are not limited to the above-mentioned purposes, and other purposes and advantages of the present invention that are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. In addition, it will be easily understood that the purposes and advantages of the present invention can be realized by the means and combinations thereof indicated in the claims.

The present invention for solving the above-described problem can be applied to a battery cell including a can including a bottom member and a side wall member connected to the bottom member and extending in the axial direction, an electrode assembly accommodated inside the can, and a cap covering an open end provided at one axial end of the side wall member.

The above bottom member may have a flat circular shape, and the above side wall member may have a circular tube shape. The above can may be formed by deep drawing a metal sheet having nickel (Ni) plated on both surfaces of steel.

The above electrode assembly can be manufactured in the form of a jelly-roll by sequentially stacking a first electrode, a separator, a second electrode, and a separator and winding them around a core shaft.

The above electrode assembly may have a cylindrical shape.

The above cap may be a circular plate made of metal.

A current collector plate connected to a second electrode of the electrode assembly may be installed at one axial end of the electrode assembly.

The above-mentioned collector plate is placed on the open end side of the can.

A terminal connection portion is provided on the radially outer edge of the above-mentioned collector plate, which extends axially outward and is electrically connected by contacting the inner surface of the side wall member.

Since the terminal connection portion extends in the axial direction, a sufficient contact area between the terminal connection portion and the side wall member can be secured.

The above battery cell has a weld formed by welding the inner surface of the side wall member and the outer surface of the cap in a state where at least a portion of the terminal connection portion in the axial direction is interposed between the inner surface of the side wall member and the outer surface of the cap.

The above-mentioned collector plate may have an electrode connecting portion that is connected to the second electrode of the electrode assembly and extends in a radial direction.

The above terminal connection portion may be positioned radially further outward than the electrode connection portion.

The above terminal connection portion and the electrode connection portion can be connected through a bending portion provided at the lower end of the terminal connection portion and changing the extension direction of the current collector plate.

The above terminal connection portion may be provided at a portion of the current collector plate that extends axially outward from the bend portion.

The above side wall member may extend axially further outward than the terminal connection portion of the above current collector plate.

The side wall member portion extending further outward in the axial direction can be welded into the weld during welding, thereby increasing the strength and volume of the weld.

The inner diameter of the inner surface of the section extending axially further outward than the terminal connection portion of the current collector plate in the above side wall member may be larger than the inner diameter of the inner surface of the terminal connection portion.

Accordingly, the side wall member does not cover the terminal end face provided at the axial outer end of the terminal connection portion of the current collector plate from the axial outer side to the axial direction.

This provides a path for the laser beam irradiated in the axial direction to directly reach the terminal connection, thereby facilitating smooth welding of the cap, can, and collector plate. In addition, the inner surface of the side wall member of the can first guides the insertion of the cap, and then the inner surface of the terminal connection portion of the collector plate guides the insertion of the cap, so that the center alignment and insertion of the cap can be smoothly achieved.

The outer surface of the above cap can be in contact with the inner surface of the terminal connection portion. Accordingly, the center of the cap with respect to the can can be aligned, and the terminal connection portion can be electrically connected to the cap.

At the edge of the above cap, an abutment portion may be provided that extends axially so that its outer surface faces the inner surface of the side wall member in the radial direction.

Since the above-mentioned mating portion extends in the axial direction, a sufficient contact area between the terminal connection portion and the mating portion can be secured.

The above-mentioned mating portion may extend axially further outward than the terminal connection portion of the above-mentioned current collector plate.

The butt joint portion extending further outward in the axial direction can penetrate the weld during welding, thereby increasing the strength and volume of the weld.

The outer diameter of the outer surface of the section extending axially further outward than the terminal connection portion of the collector plate in the above-mentioned abutment portion may be smaller than the outer diameter of the outer surface of the terminal connection portion.

Accordingly, the above-mentioned mating portion does not cover the terminal end face provided at the axial outer end of the terminal connection part of the above-mentioned current collector plate from the axial outer side to the axial direction.

This provides a path for the axially directed laser to reach the terminal connections, facilitating smoother welding of the cap, can and collector plate.

The axial outer edge of the terminal connection portion may be positioned axially further inward than the axial outer edge of the side wall member and the axial outer edge of the abutment portion.

Accordingly, the inner surface of the side wall member and the outer surface of the mating portion can face each other radially with a slight gap at an axial outer side than the terminal connection section.

The above welding portion can be formed by welding at least the axial outer edge of the inner surface of the side wall member, the axial outer edge of the outer surface of the abutment portion, and the axial outer edge of the terminal connection portion.

A curved portion having a convex shape in the axial direction can be connected to the axial inner end of the above-mentioned mating portion.

These curved portions provide elasticity to the mating portion to allow elastic deformation in the radial direction. Accordingly, the curved portion of the cap can elastically press the terminal connection portion of the current collector plate to the side wall member.

The cap can be inserted into the can until an axially inner end of the curved portion axially interferes with the collector plate. Accordingly, the insertion depth of the cap with respect to the open end can be regulated.

In addition, since the cap is pressed in radially inwardly relative to the terminal connection portion of the collector plate, the curved portion can strongly press the collector plate in the axial direction as well.

That is, the above cap can serve as a jig that fixes the collector plate by applying pressure in both the axial and radial directions before welding.

In the above cap, a support portion that extends flatly in the radial direction may be provided radially inward from the above curved portion.

The above-mentioned curved portion and the above-mentioned support portion can be connected through a first inclined portion that extends axially outward as it becomes radially inward.

The above first slope provides additional elasticity to the mating portion.

The axial outer surface of the support member may protrude further axially outward than the abutting portion of the side wall member. Accordingly, the support member may protect the welding portion and function as a support surface for the battery cell.

In the above cap, a radially extending centrifugal portion is provided radially inwardly of the support portion, and the support portion and the centrifugal portion can be connected via a second inclined portion that extends axially inward as it goes radially inward.

Accordingly, the overall rigidity of the cap can be further increased.

The above second slope may have a gentler slope than the above first slope.

The steep slope of the first slope provides radial elasticity, while the gentle slope of the second slope is advantageous in securing the rigidity of the cap.

The present invention further provides a method for manufacturing the battery cell described above.

This includes a step of inserting the collector plate into the can so that the outer surface of the terminal connection portion of the collector plate contacts the inner surface of the side wall member, a step of inserting the cap into the can so that the outer surface of the cap contacts the inner surface of the terminal connection portion of the collector plate inserted into the can, and a step of forming a weld by radiating a laser in the axial direction to an area where the outer surface of the side wall member and the inner surface of the can face each other.

In the present invention, a current collector is connected to an electrode tab provided at one of the axial ends of the electrode assembly facing the open end.

The above current collector plate has: an electrode connection portion extending radially and electrically connected by contacting the electrode tab; and a terminal connection portion extending axially outward from a radially outer edge of the second electrode connection portion and electrically connected by contacting an inner surface of the side wall member.

Then, at least a portion of the second terminal connection portion in the axial direction is interposed between the inner surface of the side wall member and the outer surface of the cap, and the inner surface of the side wall member and the outer surface of the cap are welded.

Then, in one process of welding the inner surface of the side wall member and the outer surface of the cap, the can and the cap can be seam-welded, and the terminal connection portion of the current collector plate can be brought into contact with the side wall member and/or the cap to electrically connect them.

The above cap may have an abutment portion extending axially so that its outer surface faces the inner surface of the side wall member in the radial direction.

The terminal connection portion of the above-mentioned collector plate may be interposed between the inner surface of the side wall member and the outer surface of the abutment portion.

The axial outer edge of the inner surface of the side wall member and the axial outer edge of the outer surface of the abutment portion (4) can be laser welded while the second terminal connection portion is interposed.

At this time, the axial outer edge of the inner surface of the side wall member, the axial outer edge of the outer surface of the abutment portion, and the axial outer edge of the second terminal connection portion can be laser welded together.

The axial inner end of the above-mentioned mating portion may be connected to a curved portion that extends radially inward as it goes axially inward, but the slope of the tangent line of its outer surface gradually decreases.

The insertion depth of the cap into the open end can be regulated by the interference of the axial inner end of the curved portion with the electrode connection portion of the collector plate.

In the above cap, a support portion that extends radially flatly is provided radially inwardly from the curved portion, and a first inclined portion that extends axially outward as it goes radially inwardly may be provided between the curved portion and the support portion.

Accordingly, the curved portion and the first inclined portion can form a goose neck shape that is easily elastically deformed in the radial direction but has excellent elastic restoring force. Then, when the cap is press-fitted to the open end, the curved portion is elastically deformed and allows displacement of the abutment portion radially inward, and the abutment portion can strongly press the terminal connection portion of the current collector plate radially outward. In other words, the abutment portion can play the role of a jig that closely contacts the terminal connection portion with the side wall member.

In the above cap, a radially flat centrifugal portion may be provided radially inwardly of the support portion, and a second inclined portion may be provided between the support portion and the centrifugal portion, which extends axially inwardly as it goes radially inward.

The slope of the first inclined portion may be greater than the slope of the second inclined portion. Accordingly, when the cap receives a load radially inward, the deformation is more concentrated on the first inclined portion than on the second inclined portion, so that the function of the jig that causes the abutment portion to press the terminal connection portion toward the side wall member can be more reliably exerted.

The axial outer edge of the terminal connection portion may be positioned axially further inward than the axial outer edge of the side wall member and the axial outer edge of the abutment portion.

The above side wall member and cap may be made of a similar metal material, such as aluminum or steel.

The above-mentioned collector plate may be made of the same metal material as the above-mentioned side wall member and cap.

Alternatively, the collector plate may be made of a different metal material from the side wall member and the cap, such as copper.

Then, even if they are made of different materials, the axial ends of the side wall member and the cap can be welded to each other, and the current collector plate can be maintained in a state of being interposed between them.

According to the present invention, when welding a current collector plate provided at the open end of the can to the can, the cap also functions as a jig, so that a separate space for accommodating the jig can be omitted, thereby preventing waste of internal space in the can and thereby increasing the energy density per volume of the battery cell.

In addition, according to the present invention, by welding the axial ends of the side wall member and the cap while the collector plate is interposed between the side wall member and the cap, the process of welding the collector plate to the can and the process of welding the cap to the side wall member are accomplished in a single welding process, thereby increasing the production efficiency of the cylindrical battery cell and reducing the production cost.

In addition, according to the present invention, since the collector plate is in close contact with the welding portion of the can and the cap, the heat generated when welding the can and the cap is discharged through the collector plate, thereby preventing or minimizing the phenomenon in which the welding heat is conducted through the side wall member and causes thermal damage to the separator of the electrode assembly.

In addition, according to the present invention, since welding is performed while the collector plate is strongly pressed between the can and the cap, the collector plate functions as a barrier that prevents the welding laser from entering the inside of the cap.

In addition to the effects described above, specific effects of the present invention are described below together with specific matters for carrying out the invention.

Figure 1 is a perspective view of a cylindrical battery cell of an embodiment.
Figure 2 is an exploded perspective view of the electrode assembly accommodated inside the can of Figure 1 before winding.
Figure 3 is a perspective view of the electrode assembly of Figure 2 in a laminated state before winding.
Figure 4 is a perspective view of an assembled cylindrical jelly-roll-shaped electrode assembly by winding up the laminate of Figure 3.
Figure 5 is a perspective view showing a state in which a first collector plate is joined to an electrode tab of a first electrode of an electrode assembly.
Figure 6 is a perspective view showing a state in which a second collector plate is joined to an electrode tab of a second electrode of an electrode assembly.
Figure 7 is a side cross-sectional view showing the process of accommodating an electrode assembly with a current collector plate joined inside a can.
Figure 8 is a side cross-sectional view showing the bonding process of the first current collector plate and the first electrode terminal of the electrode assembly accommodated in the can.
Figure 9 is a side cross-sectional view showing the process of covering the open end of the can containing the electrode assembly with a cap.
Figure 10 is an enlarged cross-sectional view of the open end of a battery cell with the open end of the can covered by a cap.
Figure 11 is an enlarged cross-sectional view of the edge of the cap.
Figure 12 is an enlarged cross-sectional view showing a state in which a cap is inserted into a can.
Figure 13 is an enlarged drawing showing the side wall member, current collector plate, and cap portion where welding is to be performed in the battery cell of Figure 10.
Figure 14 is a drawing showing a state in which a weld is formed by welding the side wall member, the collector plate, and the cap portion in Figure 13.
Figure 15 is a drawing showing the joint structure of the can and the collector plate of the battery cell of the comparative example.
Figure 16 is a flow chart of a battery cell manufacturing process according to the present invention.
Figures 17 and 18 illustrate a battery pack to which the battery cell of the embodiment is applied and a vehicle equipped with such a battery pack.

The above-mentioned objects, features and advantages will be described in detail below with reference to the attached drawings, so that those with ordinary skill in the art to which the present invention pertains can easily practice the technical idea of the present invention. In describing the present invention, if it is judged that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted. Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

Although the terms first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are only used to distinguish one component from another, and unless otherwise specifically stated, a first component may also be a second component.

Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

Hereinafter, the phrase “any configuration is disposed on (or below)” a component or “on (or below)” a component may mean not only that any configuration is disposed in contact with the upper surface (or lower surface) of said component, but also that another configuration may be interposed between said component and any configuration disposed on (or below) said component.

Additionally, when a component is described as being "connected," "coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to one another, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through other components.

As used herein, the singular expressions include the plural expressions unless the context clearly indicates otherwise. In this application, the terms "consisting of" or "comprising" should not be construed as necessarily including all of the various components or various steps described in the specification, and should be construed as not including some of the components or some of the steps, or may include additional components or steps.

In addition, the singular expressions used in this specification include the plural expressions unless the context clearly indicates otherwise. In this application, the terms "consisting of" or "comprising" should not be construed as necessarily including all of the various components or various steps described in the specification, and should be construed as not including some of the components or some of the steps, or may include additional components or steps.

Throughout the specification, when reference is made to "A and/or B", this means A, B, or A and B, unless otherwise stated, and when reference is made to "C through D", this means C or more and D or less, unless otherwise stated.

In explaining the embodiments, the axial direction refers to the direction in which the axis forming the winding center of the jelly-roll type electrode assembly extends, the radial direction refers to the direction approaching (centripetal) or moving away (centrifugal) from the axis, and the circumferential direction refers to the direction surrounding the axis.

Hereinafter, with reference to FIGS. 1 to 13, an embodiment of a battery cell to which the welding structure of the present invention is applied will be described in detail.

The battery cell of the embodiment may be, for example, a cylindrical battery cell having a form factor ratio (defined as the ratio of the diameter (Φ) to the height (H) of a cylindrical battery cell) of greater than about 0.4.

Here, the form factor means a value indicating the diameter and height of a cylindrical battery cell. The cylindrical battery cell may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the numerical value indicating the form factor, the first two numbers indicate the diameter of the cell, the next two numbers indicate the height of the cell, and the last number 0 indicates that the cross-section of the cell is circular.

The above battery cell may be a cylindrical battery cell having a roughly cylindrical shape, a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

A battery cell according to another embodiment may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

According to another embodiment, a battery cell may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

According to another embodiment, a battery cell may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

According to another embodiment, a battery cell may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

It goes without saying that the present invention can also be applied to battery cells having a form factor ratio of about 0.4 or less, such as an 18650 cell, a 21700 cell, etc. For the 18650 cell, the diameter is about 18 mm, the height is about 65 mm, and the form factor ratio is 0.277. For the 21700 cell, the diameter is about 21 mm, the height is about 70 mm, and the form factor ratio is 0.300.

The battery cell of the embodiment includes an electrode assembly (20), a current collector plate (31, 32) electrically connected to the electrode assembly (20), and a can (10) that accommodates the electrode assembly (20) and the current collector plate (31, 32).

The above can (10) includes a bottom member (12) and a side wall member (11) connected to the bottom member (12) and extending in the axial direction.

An open end provided at one axial end of the above side wall member (11) is sealed by covering it with a cap (16) after accommodating the electrode assembly (20) in the can (10).

The above floor member (12) has a disc shape with a hole formed in the center, and the side wall member (11) may have a circular tube shape.

The above-mentioned bottom member (12) and side wall member (11) can be manufactured by forming a metal sheet with nickel plated on the surface of steel using a deep drawing process, and trimming the front end of the side wall member (11) with a punch while holding it with a blank holder. Of course, the material of the can (10) is not limited to this.

The first electrode terminal (13) can be fitted into the hole. The first electrode terminal (13) can be fixed by riveting to the bottom member (12) with a gasket (14) interposed therebetween. The gasket (14) is interposed between the first electrode terminal (13) and the bottom member (12), sealing the inside and outside of the can (10) to prevent leakage of the electrolyte, and electrically insulating the first electrode terminal (13) and the bottom member (12).

However, the method of connecting the first electrode terminal (13) and the bottom member (12) is not limited to this. For example, if the structure can seal between the first electrode terminal (13) and the bottom member (12) and electrically insulate the first electrode terminal (13) and the bottom member (12), various other fixing methods, such as a bolt-nut joint method, a glass seal method, or a chrome coating & PP-MAH thermal bonding method, can also be applied.

The above first electrode terminal (13) may have a first polarity, and the can (10) may have a second polarity. That is, the bottom member (12) of the can (10), the side wall member (11) connected thereto, and the cap (16) connected to the side wall member (11), which will be described later, may all have a second polarity.

Accordingly, the battery cell may have both the first electrode terminal (13) and the second electrode terminal (15) arranged at the axial end, i.e., the closed end, provided with the bottom member (12). Then, the battery cell may have both the bus bar connected to the first electrode terminal (13) and the bus bar connected to the second electrode terminal (15) positioned at the upper portion of the battery cell.

In one example, the first electrode terminal (13) may be a positive terminal and the second electrode terminal (15) may be a negative terminal. Of course, the opposite may also be true.

An electrode assembly (20) is accommodated within the can (10). As shown in FIG. 2, the electrode assembly (20) is prepared by preparing a first electrode (21), a second electrode (22), and a separator (28) that are extended in the longitudinal direction with a predetermined width, and as shown in FIG. 3, a laminate is formed by sequentially stacking the first electrode (21), the separator (28), the second electrode (22), and the separator (28), and then, as shown in FIG. 4, this is wound around a coil shaft to produce a jelly-roll shape.

The above first electrode (21) may be an anode, and the above second electrode (22) may be a cathode. Of course, the opposite may also be the case.

The above first electrode (21) and second electrode (22) are manufactured in the form of sheets. The above electrode sheets are manufactured in the form of an active material layer (24) being applied to the surface of a metal foil (23). The above electrode sheets have a support portion (25) region where the active material layer (24) is applied, and a non-conductive portion (26) region where the active material layer (24) is not applied. The positive electrode sheet has a non-conductive portion (26) region on one side in the width direction, and the negative electrode sheet has a non-conductive portion (26) region on the other side in the width direction.

The non-woven portion (26) is exposed or protrudes in the width direction in the laminate. The non-woven portion (26) itself functions as an electrode tab (27).

In the above-mentioned blank portion (26), notches can be formed at a predetermined interval to form flag-shaped notching tabs (27).

In the embodiment, the notching tabs (27) are exemplified as being in the shape of an equilateral trapezoid. However, their shapes may be various shapes such as a semicircle, a semi-ellipse, a triangle, a rectangle, a parallelogram, etc.

In addition, in the embodiment, a form in which the notching tabs (27) arranged along the longitudinal direction have the same width is exemplified. However, the width of the notching tabs may be gradually or stepwise widened from the core side to the outer periphery side.

In addition, in the embodiment, a form in which the height of the notching tabs (27) gradually increases from the core side to the outer circumference side is exemplified. However, the height of these notching tabs may be implemented in a constant or gradually decreasing form.

In addition, in the embodiment, a structure is exemplified in which a notching tab (27) is deleted in a predetermined section of the centripetal end of the plain portion (26) and a predetermined section of the centrifugal end. However, it is obvious that the notching tab may not be deleted in the centripetal end of the plain portion, and the notching tab may not be deleted in the centrifugal end of the plain portion.

In the jelly roll-shaped electrode assembly (20), the notched tab (27) can be bent radially and flattened as shown in Fig. 4. The notched tab (27) can be bent radially inward or outward. In the embodiment, a structure in which the notched tab (27) is bent radially inward is exemplified.

The above-mentioned notched tabs (27) can be folded one by one during the process of forming a jelly roll-shaped electrode assembly (20) by winding the laminate. Alternatively, the above-mentioned notched tabs (27) can be folded all at once after the jelly roll-shaped electrode assembly is formed by winding the laminate.

The notched tabs (27) of the first electrode (21) and the notched tabs (27) of the second electrode (22), which are folded and covered in the radial direction in this way, can provide a plane that is substantially perpendicular to the axial direction at each of the axial ends of the electrode assembly (20).

As shown in FIGS. 5 and 6, a first collector plate (31) and a second collector plate (32) can be joined to a substantially flat surface provided by bending the notched tabs (27) exposed at both axial ends of the electrode assembly (20).

In the embodiment, it is exemplified that the first collector plate (31) is a positive collector plate and the second collector plate (32) is a negative collector plate. The first collector plate (31) may be made of aluminum and the second collector plate (32) may be made of copper.

The above-mentioned collector plate (31, 32) can be manufactured by punching, trimming, piercing, and bending a metal sheet.

Referring to FIG. 5, the first current collector plate (31) has a first terminal connection portion (312) extending radially from the center, a ring portion (313) connecting the centrifugal edge of the first terminal connection portion (312) in a circumferential direction, and a first electrode connection portion (314) extending from the ring portion (313) toward the center but not connected to the first terminal connection portion (312). The center of the first terminal connection portion (312) covers at least a portion of the core hollow portion of the electrode assembly (20).

The above first electrode connection part (314) is joined to the notched tab (27) of the first electrode (21) of the electrode assembly (20) by laser welding or the like before the electrode assembly (20) is placed in the can (10). The welding line of the laser may extend radially.

Referring to FIG. 6, the second collector plate (32) includes an inner ring (321) that defines a hole (322) corresponding to the core hollow portion of the electrode assembly (20) and is provided in a form surrounding the core hollow portion, a second electrode connection portion (323) that extends radially from the inner ring portion (321), and a second terminal connection portion (324) that is positioned on a more distal side than the second electrode connection portion (323) and is connected to the inner ring portion (321). The second terminal connection portion (324) has an outer ring form that surrounds the edge of the second collector plate (32).

The second electrode connection part (323) may be joined to the notched tab (27) of the second electrode (22) of the electrode assembly (20) by laser welding or the like before placing the electrode assembly (20) into the can (10). The welding line of the laser may extend radially.

As shown in FIGS. 7 and 8, the electrode assembly (20) is accommodated in the can (10) in a state where the first collector plate (31) is aligned toward the bottom member (12) of the can (10). At this time, an insulator (19) is interposed between the first collector plate (31) and the bottom member (12) of the can (10) so as to electrically insulate the first collector plate (31) and the bottom member (12).

And, the first terminal connection part (312) of the first collector plate (31) is joined to the first electrode terminal (13) fixed to the can (10) by resistance welding, ultrasonic welding, laser welding, or the like. The welding device for welding the first collector plate (31) and the first electrode terminal (13) can approach the back surface of the center of the first terminal connection part (312) of the first collector plate (31) through the core hollow part of the electrode assembly (20) from the open end of the can (10) to perform welding. Of course, in addition to this, the first collector plate (31) and the first electrode terminal (13) can also be joined by brazing or soldering. In other words, various methods can be applied as long as the first collector plate (31) and the first electrode terminal (13) can be electrically connected and fixed to each other.

However, the present invention does not exclude a structure in which the positive electrode tab is directly electrically connected to the positive electrode terminal while omitting the positive electrode collector plate.

With the electrode assembly (20) accommodated inside the can (10), the electrode tab (27) of the second electrode (22) and the second current collector (32) are positioned to face the open end of the side wall member (11).

After the first collector plate (31) and the first electrode terminal (13) are joined, an electrolyte can be injected into the can (10). After the electrolyte is injected, the open end of the side wall member (11) is covered and finished with a cap (16) as shown in Fig. 9.

Of course, the welding structure of the present invention can also be applied to a method of first covering the cap (16), then injecting the electrolyte, and then closing the injection port of the cap (16).

The edge of the cap (16) is joined by laser welding to the edge of the side wall member (11) as shown in Fig. 10, and thus the can (10) can be sealed.

Referring to FIGS. 10 to 14 below, the welding structure of a can and a cap according to the present invention will be described in detail.

The above second collector plate (32) has a second electrode connection portion (323) that is electrically connected by contacting the electrode tab (27) of the second electrode (22) of the electrode assembly (20), and a second terminal connection portion (324) that is electrically connected by contacting the inner surface of the side wall member (11).

The second electrode connecting portion (323) may be a circular flat plate structure extending in the radial direction. The bottom surface of the second electrode connecting portion (323) may be welded to the surface of the second electrode tab (27) by a method such as laser welding.

The second terminal connection portion (324) extends axially outward from a bend portion (328) provided on the radially outer edge of the second electrode connection portion (323).

The material of the above second collector plate (32) may be softer than the material of the side wall member (11).

When the outer diameter of the second terminal connection portion (324) is set to be slightly larger than the inner diameter of the inner surface of the side wall member (11), the bending portion (328) is elastically deformed during the process of inserting the second current collector plate (32) and the second terminal connection portion (324) is pressed into the inner surface of the side wall member (11), so that the second terminal connection portion (324) and the side wall member (11) are in close contact in the radial direction. Accordingly, in a state where the second current collector plate (32) is inserted, the outer diameter of the second terminal connection portion (324) can correspond to the inner diameter of the side wall member (11).

With the electrode assembly (20) accommodated inside the can (10), the second electrode tab (27) and the second current collector plate (32) are positioned to face the open end of the side wall member (11).

The above side wall member (11) extends axially further outward than the second terminal connection portion (324) of the second current collector plate (32). Then, as shown in FIG. 12, the inner surface of the side wall member (11) of the can (10) can first guide the insertion of the cap (40), and then the inner surface of the second terminal connection portion (324) of the second current collector plate (32) can guide the insertion of the cap (40). In other words, the above structure is not only advantageous for welding, which will be described later, but also guides the insertion of the cap (40) and facilitates the center alignment of the cap when inserting it.

The open end of the side wall member (11) is covered and finished by a cap (40). The cap (40) is a cover of the open end having a substantially disc shape. Referring to Fig. 11, the cap (40) includes, in order from the radially outer side to the inner side, a butting portion (49), a curved portion (48), a first inclined portion (47), a support portion (45), a second inclined portion (43), and a center portion (41).

On the radially outer edge of the cap (40), an abutment portion (49) is provided that extends axially so that its outer surface radially faces the inner surface of the side wall member (11) of the can (10).

With the cap (40) inserted into the can (10), the axial outer edge of the inner surface of the side wall member (11) and the axial outer edge of the outer surface of the abutment portion (49) can be arranged so that their heights correspond to each other.

At least a portion of the second terminal connection portion (324) in the axial direction is radially pressed and interposed between the side wall member (11) and the abutment portion (49) in the radial direction.

In one embodiment, the axial outer edge of the second terminal connection portion (324) is positioned axially further inward than the axial outer edge of the side wall member (11) and the axial outer edge of the abutment portion (49).

However, the present invention is not necessarily limited to this height relationship. For example, the height of the axial outer edge of the second terminal connecting portion (324) may correspond to the height of the axial outer edge of the side wall member (11) and/or the axial outer edge of the abutting portion (49), and of course, may protrude higher than that as needed.

However, if the height of the axial outer edge of the second terminal connection portion (324) is slightly lower than the height of the axial outer edge of the side wall member (11) and the axial outer edge of the abutment portion (49), a type of groove is provided between the axial outer edge of the side wall member (11) and the axial outer edge of the abutment portion (49), and the molten metal of the axial outer edge of the side wall member (11) and the axial outer edge of the abutment portion (49) penetrates and is deposited in this groove, so that the axial outer edge of the second terminal connection portion (324) is not exposed to the outside after welding.

A curved portion (48) that extends radially inwardly as it goes axially inward is connected to the axial inner end of the above-mentioned mating portion (49).

The above-mentioned curved portion (48) may have a downwardly convex shape, that is, a shape in which the slope of the tangent line of the outer surface thereof gradually decreases as it gets further away from the abutment portion (49). Since the abutment portion (49) extends vertically in the axial direction, the slope of the tangent line of the outer surface of the above-mentioned curved portion (48) may gradually decrease from 90 degrees as it gets further away from the abutment portion (49).

The above-mentioned curved portion (48) can be extended to a point where the slope of the tangent line becomes 0 degrees. More preferably, the above-mentioned curved portion (48) can be extended further past 0 degrees to an angle where the slope of the tangent line corresponds to the first slope of the first inclined portion (47) described later.

The point where the slope of the tangent line in the above curved portion (48) becomes 0 degrees may be the portion that extends most inwardly in the axial direction from the curved portion (48).

The insertion depth of the cap (40) into the open end can be regulated by the point where the axial inner end of the curved portion (48), i.e., the point where the inclination of the tangent line becomes 0 degrees, interferes with the surface of the second electrode connecting portion (323) of the current collector plate (32).

The cap (40) presses the second terminal connection portion (324) of the second collector plate (32) in a centrifugal direction, and also presses the radial edge of the second electrode connection portion (323) of the second collector plate (32) in an axial direction inward. Accordingly, the second terminal connection portion (324) of the second collector plate (32) is firmly fixed between the side wall member (11) and the cap (40).

The second collector plate (32) itself, unlike the cap (40), may not have the rigidity to exert elastic force to strongly press its own second terminal connection part (324) to the side wall member (11).

Accordingly, if the shape of the cap (40) having higher rigidity than the second collector plate (32) is designed to have elasticity, the cap (40) can be strongly pressed against the side wall member (11), and the second collector plate (32), which must be strongly pressed for welding to the side wall member (11), can be strongly pressed against the side wall member (11) by the cap (40), thereby allowing the cap (40) to also function as a jig for welding the second collector plate (32) to the side wall member (11).

In the cap (40), a support portion (45) is provided that extends horizontally in the radial direction radially inward from the curved portion (48). Since the surface of the support portion (45) has a flat ring shape, it functions as a foot of the battery cell when the battery cell illustrated in Fig. 1 is turned over.

The axial outer surface of the support member (45) is positioned at the same height as the axial outer end of the abutment member (49) as illustrated, or is positioned axially further outward than that. Accordingly, even if the battery cell illustrated in Fig. 1 is turned over so that the cap (40) touches the floor and the battery cell is placed, the welding area of the cap (40) and the can (10) does not directly support the load of the battery cell, thereby protecting the welding area.

Between the above-mentioned curved portion (48) and the above-mentioned support portion (45), a first inclined portion (47) is provided that extends radially inwardly and axially outwardly, but whose inclination is substantially constant as the first inclination. In the embodiment, the first inclination is exemplified as being approximately 45 degrees. Then, the angle between the first inclined portion (47) and the abutting portion (49) can be approximately 45 degrees.

In the cap (40), a centrifugal portion (41) is provided that extends radially and horizontally radially inwardly from the support portion (45). The axial inner surface of the centrifugal portion (41) is positioned axially further outward than the axial inner end of the curved portion (48).

Accordingly, when the cap (40) is pressed in, the curved portion (48) can contact the second collector plate (32) before the axial inner surface of the centrifugal portion (41) contacts the second collector plate (32). That is, according to the embodiment, the pressing depth of the cap (40) can be regulated by the interference between the curved portion (48) and the second electrode connecting portion (323) of the second collector plate (32).

Between the support member (45) and the center member (41), a second inclined member (43) is provided that extends axially inwardly as it goes radially inward, but has a substantially constant second inclination. In the embodiment, the second inclination is exemplified as being approximately 22.5 degrees.

The second slope may be smaller than the first slope. Accordingly, when the cap (40) receives a load in the radial direction, the radial ends of the first slope (47) may be deformed more effectively than the radial ends of the second slope (43). This difference in slope allows the abutment portion (49) of the cap (40) to more reliably function as a jig that presses the second terminal connection portion (324) of the second collector plate (32).

The radial length of the support portion (45) may be at least twice as long as the length of the section occupied in the radial direction by the abutment portion (49), the curved portion (48), and the first inclined portion (47). Then, since the support portion (45) has relatively higher rigidity in the radial direction, the radial load applied to the cap (40) from the outer peripheral surface of the cap (40) may be concentrated on the radially outer section rather than the support portion (45). This difference in length also allows the abutment portion (49) of the cap (40) to more reliably function as a jig that presses the second terminal connection portion (324) of the second collector plate (32).

Referring to Fig. 12, when a load is applied to the abutment portion (49) radially inwardly, the curved portion (48) is mainly elastically deformed, and the connection portion between the first inclined portion (47) and the support portion (45) can be mainly elastically deformed. In addition, according to this goose neck structure, since the elastic deformation section is large, the elastic force applied in the direction in which the abutment portion (49) is restored radially outward again also acts significantly.

Accordingly, when the cap (40) is pressed into the open portion of the can (10), the elastic force of the cap (40) acts in a direction to restore the abutment portion (49) radially outward, and the second terminal connection portion (324) of the second collector plate (32) is strongly pressed while being interposed between the side wall member (11) and the abutment portion (49), as illustrated in FIG. 13.

In this state, the axial end of the side wall member (11) and the axial end of the abutting portion (49) are welded by a laser (L) irradiated in the axial direction as shown in Fig. 13. The irradiation direction of the laser may be parallel to the axial direction.

Accordingly, at least a portion of the second terminal connection portion (324) in the axial direction is interposed between the inner surface of the side wall member (11) and the outer surface of the cap (40), and the inner surface of the side wall member (11) and the outer surface of the cap (40) are welded to form a weld (W). A portion of the second terminal connection portion (324) may also be welded into this weld (W).

The side wall member (11) portion that extends further outward in the axial direction and the mating portion (49) portion face each other radially with a slight gap, thereby providing a path for the laser irradiated in the axial direction to directly reach the second terminal connection portion (324), thereby allowing the second collector plate (32) to be heated before excessive heat is generated, thereby facilitating the triple welding of the cap (40), the can (10), and the second collector plate (32).

In addition, the portion of the side wall member (11) that extends further outward in the axial direction and the portion of the abutment portion (49) are welded into the weld (W) during welding, thereby increasing the strength and volume of the weld (W).

The above side wall member (11) and cap (40) may be made of a similar metal material, such as aluminum or steel.

The second collector plate (32) may be made of the same metal material as the side wall member (11) and the cap (40). Then, the second collector plate (32) may be welded together in the process of welding the side wall member (11) and the cap (40).

In contrast, the second collector plate (32) may be made of a different metal material from the side wall member (11) and the cap (40), such as copper.

Then, even if they are made of different materials, the second collector plate (32) can be welded together in the process of welding the side wall member (11) and the cap (40), and even if the welding of the second collector plate (32) is somewhat insufficient due to the fact that they are made of different materials, the axial ends of the side wall member (11) and the cap (40) can be welded to each other, and the collector plate can be maintained in a state of being interposed between them, so there is no problem with the electrical connection between the collector plate and the can.

Referring to FIG. 16 below, an embodiment of a method for manufacturing a battery cell according to the present invention will be described.

First, the first electrode terminal (13) is fixed to the hole provided in the bottom member (12) of the can (10). At this time, a gasket (14) is interposed between the bottom member (12) and the electrode terminal (13) to ensure electrical insulation and sealing therebetween. In the embodiment, the form in which the first electrode terminal (13) is fixed by riveting while interposing the gasket (14) is exemplified, but it is obvious that various other known methods that can fix the first electrode terminal (13) to the bottom member (12) while performing insulation sealing may be applied.

Next, an electrode assembly (20) having collector plates (31, 32) welded to both ends is inserted into the can. Then, the first collector plate (31) faces and comes into contact with the first electrode terminal (13), the second electrode connection portion (323) of the second collector plate (32) faces the open end, and the second terminal connection portion (324) of the second collector plate (32) comes into contact with the inner surface of the side wall member (11) of the can (10). In this state, the first collector plate (31) and the first electrode terminal (13) are welded.

Next, a cap (40) is pressed into the open end of the can (10). Since the outer surface of the cap (40) is provided with a curved portion (48) whose outer diameter gradually decreases as it goes axially inward, the inner edge of the axially outer end of the second terminal connection portion (324) of the second current collector (32) begins to be naturally pressed by the curved portion (48), and the second terminal connection portion (324) comes into contact with the abutment portion (49) of the cap (40) and is pressed radially outward. The insertion of the cap (40) can be performed until the curved portion (48) of the cap (40) axially contacts and interferes with the second electrode connection portion (323).

Next, the axial end of the side wall member (11) of the can (10) and the axial end of the mating portion (49) of the cap (40) are welded.

In the battery cell of this embodiment, unlike the battery cell of the comparative example illustrated in FIG. 15, since the cap (40) also functions as a jig when welding the second collector plate (32) to the can (10), there is no need to provide a separate space for accommodating the jig inside the can. Accordingly, the energy density per volume of the battery cell can be increased without wasting the internal space of the can (10).

In addition, unlike the battery cell of the comparative example illustrated in FIG. 15, the battery cell of the embodiment welds the axial ends of the side wall member (11) and the cap (40) while the second collector plate (32) is interposed between the side wall member (11), thereby resolving the process of welding the second collector plate (32) to the can (10) and the process of welding the cap (40) to the side wall member (11) in a single welding process. Accordingly, the production efficiency of the cylindrical battery cell can be increased and the production cost can be reduced.

The battery cell (72) manufactured through the welding structure and welding process described above can be accommodated in the housing (71) of the battery pack (70) as illustrated in Fig. 17. The battery pack (70) may be configured using a battery module, which is an intermediate form of assembly, or the battery pack (70) may be configured directly without a battery module as illustrated.

Since the battery cell (72) described above has a large volume in itself, there is no particular difficulty in implementing the battery pack (70) even without using an intermediate structure called a battery module. In addition, the battery cell (72) has a low internal resistance and a higher energy density. Accordingly, the energy density of the battery pack (70) equipped with the battery cell (72) can be implemented even higher.

The battery pack (70) with such an increased energy density can store the same amount of energy while reducing its volume and load. Therefore, if the battery pack (70) to which such battery cells (72) are applied is mounted on a vehicle such as an automobile (80) that uses electricity as an energy source as shown in Fig. 18, the mileage of the vehicle can be further increased in proportion to the energy consumed.

It should be understood that the above-described embodiments are illustrative in all respects and not restrictive, and the scope of the present invention will be indicated by the claims that follow rather than by the detailed description set forth above. And the meaning and scope of the claims that follow, as well as all changes and modifications that can be derived from the equivalent concept thereof, should be interpreted as being included in the scope of the present invention.

Although the present invention has been described with reference to the drawings as examples, it is obvious that the present invention is not limited to the embodiments and drawings disclosed in this specification, and that various modifications can be made by those skilled in the art within the scope of the technical idea of the present invention. In addition, even if the effects according to the configuration of the present invention were not explicitly described while describing the embodiments of the present invention, it is natural that the effects that can be predicted by the corresponding configuration should also be recognized.

10: Can
11: Side wall member
12: Flooring
13: First electrode terminal
14: Gasket
15: Second electrode terminal
19: Insulator
20: Electrode assembly
21: 1st electrode
22: Second electrode
23: Metal foil
24: Active material layer
25: Maintenance Department
26: No-nonsense
27: Electrode tab (notching tab)
28: Membrane
31: First collector plate (bipolar collector plate)
312: 1st terminal connection
313: Ringbu
314: First electrode connection
32: Second Collection Plate
321: Inner ring
322: Hall
323: Second electrode connection
324: Second terminal connection
328: bend
40: Cap
41: Centripetal
43: 2nd Slope Division
45: Support
47: 1st Slope Division
48: Curved surface
49: The buttocks
70: Battery Pack
71: Housing
72: Battery Cell
80: Vehicle
W: Welding

Claims (16)

A can comprising a floor member and side wall members connected to the floor member and extending axially;
An electrode assembly accommodated inside the can;
A cap covering an open end provided at one axial end of the above side wall member; and
A battery cell including a current collector plate connected to the electrode of the electrode assembly and arranged on the open end side,
The above current collector plate is provided with a terminal connection portion that extends axially outwardly on the radially outer edge of the above current collector plate and is electrically connected by contacting the inner surface of the side wall member.
A battery cell including a weld formed by welding the inner surface of the side wall member and the outer surface of the cap in a state where at least a portion of the terminal connection portion in the axial direction is interposed between the inner surface of the side wall member and the outer surface of the cap.
In claim 1,
The above current collector plate has an electrode connection portion that is connected to the electrode of the electrode assembly and extends radially,
The above terminal connection portion is positioned radially further outside than the above electrode connection portion,
A battery cell, wherein the terminal connection portion and the electrode connection portion are connected through a bending portion provided at the lower end of the terminal connection portion and changing the extension direction of the current collector plate.
In claim 1,
A battery cell wherein the side wall member extends axially further outward than the terminal connection portion of the current collector plate.
In claim 3,
A battery cell, wherein the inner diameter of the inner surface of the section extending axially further outward than the terminal connection portion of the current collector plate in the side wall member is larger than the inner diameter of the inner surface of the terminal connection portion.
In claim 1,
A battery cell in which the outer surface of the above cap is in contact with the inner surface of the terminal connection part.
In claim 5,
A battery cell, wherein an abutment portion is provided on the edge of the cap so that the outer surface thereof radially faces the inner surface of the side wall member and extends axially.
In claim 6,
A battery cell in which the above-mentioned mating portion extends further outward in the axial direction than the terminal connection portion of the above-mentioned current collecting plate.
In claim 6,
A battery cell, wherein the outer diameter of the outer surface of the section extending axially further outward than the terminal connection portion of the current collector plate in the above-mentioned mating portion is smaller than the outer diameter of the outer surface of the terminal connection portion.
In claim 6,
The above welding portion is a battery cell formed by welding at least the axial outer edge of the inner surface of the side wall member, the axial outer edge of the outer surface of the abutment portion, and the axial outer edge of the terminal connection portion.
In claim 6,
A curved portion having a convex shape in the axial direction is connected to the axial inner end of the above-mentioned mating portion,
A battery cell, wherein the axial inner end of the above-mentioned curved portion axially interferes with the above-mentioned current collector plate, thereby regulating the insertion depth of the cap with respect to the above-mentioned open end.
In claim 10,
In the above cap, a support portion is provided that extends radially flatly radially inward from the above curved portion,
A battery cell, wherein the above-mentioned curved portion and the above-mentioned support portion are connected through a first inclined portion that extends axially outward as it becomes radially inward.
In claim 11,
A battery cell, wherein the axial outer surface of the support member protrudes further outward in the axial direction than the portion that abuts against the side wall member.
In claim 11,
In the above cap, a radially extending centrifugal portion is provided radially inward from the support portion,
A battery cell, wherein the above-mentioned support member and the center member are connected through a second inclined member that extends axially inward as it becomes radially inward.
In claim 13,
A battery cell, wherein the second slope has a gentler slope than the first slope.
In claim 6,
A battery cell, wherein the axial outer edge of the terminal connection portion is positioned axially further inward than the axial outer edge of the side wall member and the axial outer edge of the mating portion.
A method for manufacturing a battery cell according to any one of claims 1 to 15,
A step of inserting the current collector plate into the can so that the outer surface of the terminal connection part of the current collector plate contacts the inner surface of the side wall member;
A step of inserting the cap into the can so that the outer surface of the cap contacts the inner surface of the terminal connection part of the current collector plate inserted into the can; and
A method for manufacturing a battery cell, comprising: a step of forming a weld by radiating a laser in an axial direction to an area where the outer surface of the side wall member and the inner surface of the can face each other.

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