KR20210126514A - Battery module and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a battery module and a method for manufacturing the same. The battery module according to an embodiment of the present invention includes a first member and a second member coupled in a direction crossing each other, wherein the first member and the second member are welded to each other, a welding unit of the first member and the second member includes a first welding unit formed in the first member with respect to a coupling surface of the first member and the second member, and a second welding unit formed on the second member, and the first welding unit and the second welding unit have shapes that are asymmetric to each other.

Description

Battery module and manufacturing method thereof

The present invention relates to a battery module and a method for manufacturing the same, and more particularly, to a battery module for preventing spatter inflow by welding and a method for manufacturing the same.

Secondary batteries that are easy to apply according to product groups and have electrical characteristics such as high energy density are universally applied to electric vehicles or hybrid vehicles driven by an electric drive source, as well as portable devices, and power storage devices. These secondary batteries are attracting attention as a new energy source for improving eco-friendliness and energy efficiency in that not only the primary advantage of being able to dramatically reduce the use of fossil fuels but also the fact that no by-products are generated from the use of energy.

While one or two or three battery cells are used per device in small mobile devices, medium and large devices such as automobiles require high output and high capacity. Accordingly, a medium or large-sized battery module in which a plurality of battery cells are electrically connected is used.

Since it is desirable to manufacture the mid- to large-sized battery module as small as possible in size and weight, a prismatic battery, a pouch-type battery, etc. that can be stacked with a high degree of integration and have a small weight to capacity are mainly used as the battery cells of the medium and large-sized battery module. On the other hand, the battery module, in order to protect the cell stack from external impact, heat, or vibration, the front and rear are opened may include a frame member for accommodating the battery cell stack in an internal space.

1 is a perspective view showing a battery module having a conventional module frame. FIG. 2 is a view showing a part of a cross-sectional view taken along the XZ plane of FIG. 1 . FIG. 3 is a diagram illustrating a case in which welding lines are misaligned in FIG. 2 .

Referring to FIG. 1 , the battery module includes a module frame 10 with front and back open front and rear to cover a battery cell stack formed by stacking a plurality of battery cells, and an end plate covering the front and rear surfaces of the module frame 10 ( 20) may be included. The module frame 10 may include a U-shaped frame 10a and an upper plate 10b covering an open upper portion of the U-shaped frame 10a. The end plate 20 may include a front plate 20a covering one side of the module frame 10 and a rear plate 20b covering the other side of the module frame 10 .

In order to form such a battery module, in a state in which the battery cell stack is mounted inside the module frame 10, welding or the like is performed to combine the U-shaped frame 10a and the upper plate 10b of the module frame 10. can do.

Referring to FIG. 2 , a welding portion WP may be formed between the upper plate 10b and a side portion of the U-shaped frame 10a. At this time, in order to form the weld WP, it is necessary to fix the U-shaped frame 10a and the upper plate 10b so that the joint surfaces of the side portion of the U-shaped frame 10a and the upper plate 10b are positioned to correspond to each other. have. However, there is a limitation in fixing the U-shaped frame 10a and the upper plate 10b to closely correspond to each other, and this has a problem in that the welding is not performed smoothly.

In addition, laser welding may be performed for the welding, and internal components including battery cells may be damaged due to the laser itself or welding spatters penetrated during the welding process. Referring to FIG. 3 , when the welding lines are misaligned, much more welding spatters are introduced into the battery module in which the battery cells are located, and thus a greater problem may occur.

Therefore, there is a need for a technique capable of solving such a problem in the prior art.

An object of the present invention is to provide a battery module and a method for manufacturing the same for preventing spatter inflow by welding.

However, the problems to be solved by the embodiments of the present invention are not limited to the above problems and may be variously expanded within the scope of the technical idea included in the present invention.

The battery module according to an embodiment of the present invention includes a first member and a second member coupled in a direction crossing each other, wherein the first member and the second member are welded to each other, and the first member and the second member are welded together. The two-member welding portion includes a first welding portion formed in the first member and a second welding portion formed in the second member based on a coupling surface between the first member and the second member, wherein the first The welding part and the second welding part have shapes that are asymmetric to each other.

The battery module further includes a battery cell stack including a plurality of battery cells, and a module frame accommodating the plurality of battery cell stacks, wherein the module frame includes an open U-shaped frame, and the battery and a plate-shaped plate coupled to the U-shaped frame while covering the cell stack, wherein the U-shaped frame includes a bottom and two side surfaces facing each other, wherein the first member is the plate-shaped plate, and the second The member is the side part.

One side of the plate-shaped plate adjacent to the coupling surface and an outer surface of the side part may be formed in parallel.

A depression may be formed in one side of the plate-shaped plate, and a coupling surface of the plate-shaped plate and the side portion may be formed in the depression.

It may further include an end plate coupled to the module frame on the front and rear of the battery cell stack.

A method for manufacturing a battery module according to another embodiment of the present invention includes welding a first member and a second member that are coupled in a direction crossing each other, and welding the first member and the second member In the step of performing laser welding in a tilted state on the coupling surface of the first member and the second member, the coupling surface of the first member and the second member and an extension line in the irradiation direction of the welding irradiation beam cross do.

The battery module manufacturing method includes the steps of mounting a battery cell stack in which a plurality of battery cells are stacked on an open U-shaped frame, and converting the battery cell stack into a plate-shaped plate on the open U-shaped frame. The method further includes the step of covering, and the welding-joining of the first member and the second member includes welding-joining the plate-shaped plate and the U-shaped frame.

The welding irradiation beam may be incident on the U-shaped frame at a shifted position with respect to the coupling surface.

The U-shaped frame may include a bottom portion and two side portions facing each other, and welding the plate-shaped plate and the U-shaped frame may weld the side portion and the plate-shaped plate to each other.

One side of the plate-shaped plate adjacent to the coupling surface and an outer surface of the side part may be formed in parallel.

The U-shaped frame includes a bottom part and two side parts facing each other, and the welding-combining of the plate-shaped plate and the U-shaped frame may include a welding process in which the plate-shaped plate is overlapped on the upper end of the side part. have.

A depression may be formed on one side of the plate-shaped plate, and a coupling surface between the plate-shaped plate and the U-shaped frame may be formed in the depression.

Welding the plate-shaped plate and the U-shaped frame may be performed _{in an N 2 gas atmosphere.}

The tilting angle may be 13.5 degrees to 21.5 degrees.

The tilting angle may be 15 to 20 degrees.

The welding of the plate-shaped plate and the U-shaped frame may include dual-beam laser welding based on a gap between the plate-shaped plate and the U-shaped frame.

According to embodiments, it is possible to prevent spatter from being introduced into the battery module by the tilt welding process. Accordingly, it is possible to reduce the occurrence of battery cell defects due to welding.

1 is a perspective view showing a battery module having a conventional module frame.
FIG. 2 is a view showing a part of a cross-sectional view taken along the XZ plane of FIG. 1 .
FIG. 3 is a diagram illustrating a case in which welding lines are misaligned in FIG. 2 .
4 is a perspective view illustrating a module frame and an end plate in a battery module according to an embodiment of the present invention.
5 is an exploded perspective view illustrating a battery module according to an embodiment of the present invention.
6 is a perspective view illustrating a state in which the components of the battery module of FIG. 5 are combined.
7 to 11 are views illustrating a method of manufacturing a battery module according to another embodiment of the present invention.
12 is a graph showing tensile strength according to a tilting angle in a method for manufacturing a battery module according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, various embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement them. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly explain the present invention, parts irrelevant to the description are omitted, and the same reference numerals are given to the same or similar elements throughout the specification.

In addition, since the size and thickness of each component shown in the drawings are arbitrarily indicated for convenience of description, the present invention is not necessarily limited to the illustrated bar. In order to clearly express various layers and regions in the drawings, the thicknesses are enlarged. And in the drawings, for convenience of description, the thickness of some layers and regions are exaggerated.

Also, when a part of a layer, film, region, plate, etc. is said to be “on” or “on” another part, it includes not only cases where it is “directly on” another part, but also cases where another part is in between. . Conversely, when we say that a part is "just above" another part, we mean that there is no other part in the middle. In addition, to be "on" or "on" the reference portion means to be located above or below the reference portion, and to necessarily mean to be located "on" or "on" in the direction opposite to gravity no.

In addition, throughout the specification, when a part "includes" a certain component, this means that other components may be further included, rather than excluding other components, unless otherwise stated.

In addition, throughout the specification, when referring to "planar", it means when the target part is viewed from above, and "in cross-section" means when viewed from the side when a cross-section of the target part is vertically cut.

4 is a perspective view illustrating a module frame and an end plate in a battery module according to an embodiment of the present invention. 5 is an exploded perspective view illustrating a battery module according to an embodiment of the present invention. 6 is a perspective view illustrating a state in which the components of the battery module of FIG. 5 are combined.

Referring to FIG. 4 , the battery module 100 according to this embodiment has a module frame 500 with one side facing each other and the other side open in one direction, and a module frame 500 from one side and the other side of the module frame 500 . ) and an end plate 150 coupled with it. The module frame 500 covers the battery cell stack formed by stacking a plurality of battery cells except for both sides open in the y-axis direction.

The module frame 500 according to the present embodiment may include a U-shaped frame 300 and an upper plate 400 covering an open upper portion of the U-shaped frame 300 . The end plate 150 may include a front plate 150a covering one side of the module frame 500 and a rear plate 150b covering the other side of the module frame 500 .

In order to form such a battery module, in a state in which the battery cell stack is mounted inside the module frame 500 , after aligning the module frame 500 and the end plate 150 , the open side of the module frame 500 . And the front plate 150a and the rear plate 150b may be welded to a corner portion defining the other side. As shown in FIG. 4 , there may be a total of 10 coupling portions CP by welding.

Referring to FIGS. 5 and 6 , the battery module 100 according to the present embodiment includes a battery cell stack 120 including a plurality of battery cells 110 , and a U-shaped frame in which the upper surface, the front surface and the rear surface are open. 300 , the upper plate 400 covering the upper portion of the battery cell stack 120 , the end plate 150 and the battery cell stack 120 respectively positioned on the front and rear surfaces of the battery cell stack 120 , and and a bus bar frame 130 positioned between the end plates 150a and 150b. In addition, the battery module 100 includes a thermally conductive resin layer 310 positioned between the U-shaped frame 300 and the battery cell stack 120 . The thermally conductive resin layer 310 is a kind of heat dissipation layer, and may be formed by coating a material having a heat dissipation function.

When the open sides of the U-shaped frame 300 are referred to as the first side and the second side, respectively, the U-shaped frame 300 is the battery cell stack 120 corresponding to the first side and the second side. Among the remaining outer surfaces except for the surface, it has a bent plate-shaped structure so as to continuously cover the front, lower and rear surfaces adjacent to each other. The upper surface corresponding to the lower surface of the U-shaped frame 300 is open.

The upper plate 400 has a single plate-shaped structure that covers the remaining upper surfaces except for the front, lower and rear surfaces covered by the U-shaped frame 300 . Specifically, the U-shaped frame 300 according to the present embodiment includes a bottom portion 300a and two side portions 300b facing each other. The U-shaped frame 300 and the upper plate 400 may form a structure surrounding the battery cell stack 120 by being coupled by welding or the like in a state in which corresponding corner portions are in contact with each other. That is, the U-shaped frame 300 and the upper plate 400 may be formed with a coupling portion CP formed by a coupling method such as welding at the corner portions corresponding to each other.

Before the battery cell stack 120 described in FIG. 5 is mounted on the bottom portion 300a of the U-shaped frame 300 , a thermal conductive resin is applied to the bottom portion 300a of the U-shaped frame 300 , and thermoelectric The conductive resin may be cured to form the thermally conductive resin layer 310 .

Before forming the thermally conductive resin layer 310 , that is, before the applied thermally conductive resin is cured, the battery cell stack 120 moves along a direction perpendicular to the bottom portion 300a of the U-shaped frame 300 . It may be mounted on the bottom portion 300a of the U-shaped frame 300 while moving. Thereafter, the thermally conductive resin layer 310 formed by curing the thermally conductive resin is positioned between the bottom portion 300a of the U-shaped frame 300 and the battery cell stack 120 . The thermally conductive resin layer 310 may serve to transfer heat generated in the battery cell 110 to the bottom of the battery module 100 and to fix the battery cell stack 120 .

The battery cell stack 120 includes a plurality of battery cells 110 stacked in one direction, and the plurality of battery cells 110 may be stacked in the Y-axis direction as shown in FIG. 5 . In other words, the direction in which the plurality of battery cells 110 are stacked may be the same as the direction in which the two side portions of the U-shaped frame 300 face each other. The battery cell 110 is preferably a pouch-type battery cell.

The width of the side portion 300b and the upper plate 400 of the U-shaped frame 300 according to the present embodiment may be the same as each other. In other words, the edge portion extending along the X-axis direction from the upper plate 400 and the edge portion extending along the X-axis direction from the side portion 300b of the U-shaped frame 300 meet directly to be combined by a method such as welding. can

Hereinafter, a method for manufacturing a battery module and a battery module structure according to an embodiment of the present invention will be described with reference to FIGS. 7 to 11 .

Referring to FIG. 7 , the method for manufacturing a battery module according to this embodiment includes laminating the battery cell stack 120 on the bottom part 300a of the U-shaped frame 300 with an open top. At this time, in the direction (Z-axis direction) perpendicular to the stacking direction of the plurality of battery cells 110 included in the battery cell stack 120 , the battery cell stack 120 is positioned at the bottom of the U-shaped frame 300 ( 300a) is preferably inserted.

In the battery module manufacturing method according to this embodiment, before mounting the battery cell stack 120 on the bottom part 300a of the U-shaped frame 300 , the battery cells 110 included in the battery cell stack 120 . ) may further include connecting the battery cell stack 120 and the bus bar frame 130 while moving the bus bar frame 130 in a direction opposite to the direction in which the electrode leads protrude. Additionally, in the battery module manufacturing method, a thermal conductive resin is applied to the bottom portion 300a of the U-shaped frame 300 before mounting the battery cell stack 120 to the bottom portion 300a of the U-shaped frame 300 . It may further include the step of applying.

Referring to FIG. 8 , the method of manufacturing a battery module according to this embodiment includes mounting the upper plate 400 to cover the battery cell stack 120 on the open U-shaped frame 300 . In this embodiment, the upper plate 400 is disposed adjacent to the upper portion of the U-shaped frame 300 in the vertical Z-axis direction, and then combined by welding or the like to form a battery module as shown in FIG. 6 . However, in a modified embodiment not limited to this method, after placing the plate-shaped lower plate on the floor and mounting the battery cell stack 120 on the lower plate, the U-shaped frame with an open bottom is stacked with the battery cells. The sieve 120 may be covered. In this case, a thermally conductive resin layer formed by applying the aforementioned thermally conductive resin may be formed between the lower plate and the battery cell stack 120 . In this embodiment, after arranging the lower portion of the U-shaped frame whose lower portion is opened in the vertical Z-axis direction to be adjacent to the lower plate, it may be coupled by a method such as welding.

At this time, the welding method according to the present embodiment will be described with reference to FIGS. 9 and 10 .

FIG. 9 is a partial cross-sectional view taken along the first cross-section of FIG. 6 . FIG. 10 is a cross-sectional view illustrating a recessed portion of the upper plate of FIG. 9 .

Referring to FIG. 9 , the welding process of welding the upper plate 400 and the U-shaped frame side part 300b may be performed in a state in which the upper plate 400 is overlapped on the upper side of the side part 300b. According to a modified embodiment, the module frame structure including the upper plate 400 and the U-shaped frame 300 described above may be replaced with a module frame structure including a plate-shaped lower plate and an open U-shaped frame. have.

According to the present embodiment, in the step of welding the upper plate 400 and the side portion 300b of the U-shaped frame, the coupling surface CS of the upper plate 400 and the U-shaped frame side portion 300b is tilting (tilting). ) can be laser welded. Alternatively, in a state in which the module frame 500 including the upper plate 400 and the U-shaped frame 300 is fixed, the laser optical system itself emitting a welding irradiation beam may be tilted to perform laser welding.

At this time, the coupling surface CS of the upper plate 400 and the U-shaped frame side portion 300b may cross an extension line in the irradiation direction of the welding irradiation beam. The welding irradiation beam may pass between the first point (a) and the second point (b) shown in FIG. 9 . The first point (a) is a portion located at the outermost portion of the coupling surface (CS), and the second point (b) is a portion located at the innermost portion of the coupling surface (CS). The welding irradiation beam may have an angle that is tilted to have a range passing between the first point (a) and the second point (b). According to this embodiment, the tilted angle may be approximately 15 to 20 degrees.

The welding irradiation beam may be incident on the side portion 300b of the U-shaped frame at a shifted position with respect to the coupling surface CS. The shifted position is a position moved in the downward direction of the U-shaped frame side part 300b with respect to the upper plate 400 . As the welding irradiation beam is incident at a position shifted downward from the engagement surface CS, the possibility that the welding line passes through the engagement surface CS increases. Therefore, even if the welding line is misaligned, it is possible to not only form a welding part to have sufficient tensile strength around the coupling surface CS, but also to minimize the possibility of spatter entering the battery module.

12 is a graph showing tensile strength according to a tilting angle in a method for manufacturing a battery module according to an embodiment of the present invention.

Referring to FIG. 12 , since the tilting angle has a tensile strength of 10 kN or more in a range between 13.5 degrees and 21.5 degrees, it may have a strong tensile strength that can sufficiently withstand an external impact. Preferably, the tilting angle may be 15 to 20 degrees.

The welding of the upper plate 400 and the side portion 300b of the U-shaped frame may be performed _{in an N 2 gas atmosphere.} When _{welding in an N 2} gas atmosphere, it is possible to reduce the inflow of spatter into the interior.

According to the present embodiment, welding may be laser welding, and as a modified embodiment, dual beam laser welding may be performed based on a gap between the upper plate 400 and the U-shaped frame side portion 300b.

Referring back to FIG. 9 , according to this embodiment, the welding portion WP of the upper plate 400 and the side portion 300b is the upper plate based on the coupling surface CS of the upper plate 400 and the side portion 300b. It includes a first welded portion WP1 formed on the 400 and a second welded portion WP2 formed on the side portion 300b. In this case, the first welding part WP1 and the second welding part WP2 have asymmetric shapes.

One side of the upper plate 400 adjacent to the coupling surface CS and the outer surface of the side part 300b may be formed in parallel. In other words, as shown in FIG. 9 , one side of the upper plate 400 and the outer side of the U-shaped frame side part 300b may be disposed on the same plane. However, it is not limited to being completely positioned on the same plane.

Referring to FIG. 10 , a depression DP is formed on one side of the upper plate 400 , and the coupling surface CS between the upper plate 400 and the side surface 300b shown in FIG. 9 in the depression DP. can be formed.

Referring to Figure 11, the battery module manufacturing method according to this embodiment, the step of combining the upper plate 400 and the side portion 300b of the U-shaped frame and the end plate 150 on both open sides of the U-shaped frame, respectively. It includes the step of combining The tilting welding according to the present embodiment is not necessary for welding the end plate 150 and the module frame. Because, a separate anti-spatter guard may be formed between the end plate 150 and the module frame to prevent the inflow of spatter.

In the above, the welding-coupled structure of the side portion 300b and the upper plate 400 of the U-shaped frame 300 has been described as an example, but in a modified embodiment, the first member and the second member that are coupled in the intersecting direction The present invention can also be applied to a welded joint structure.

Meanwhile, one or more battery modules according to an embodiment of the present invention may be packaged in a pack case to form a battery pack.

The above-described battery module and battery pack including the same may be applied to various devices. These devices can be applied to transportation means such as electric bicycles, electric vehicles, hybrid vehicles, etc., but the present invention is not limited thereto and can be applied to various devices that can use a battery module and a battery pack including the same. It belongs to the scope of the invention.

Although the preferred embodiment of the present invention has been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the

300: U-shaped frame
300a: bottom
300b: side part
400: top plate
500: module frame

Claims (16)

Comprising a first member and a second member coupled in a direction crossing each other,
The first member and the second member are welded to each other,
The welding portion of the first member and the second member may include a first welding portion formed in the first member based on a coupling surface of the first member and the second member, and a second welding portion formed in the second member. includes,
The first welding portion and the second welding portion battery module having a shape that is asymmetric to each other. In claim 1,
A battery cell stack including a plurality of battery cells, and
Further comprising a module frame for accommodating the plurality of battery cell stacks,
The module frame includes a U-shaped frame, and a plate-shaped plate coupled to the U-shaped frame,
The U-shaped frame includes a bottom portion and two side portions facing each other,
The first member is the plate-shaped plate, and the second member is the side part of the battery module. In claim 2,
A battery module in which one side of the plate-shaped plate adjacent to the coupling surface and an outer surface of the side part are formed side by side. In claim 2,
A battery module in which a depression is formed on one side of the plate-shaped plate, and a coupling surface of the plate-shaped plate and the side portion is formed in the depression. In claim 2,
Battery module further comprising an end plate coupled to the module frame on the front and rear of the battery cell stack. A method comprising: welding a first member and a second member coupled in a direction crossing each other;
In the welding-joining of the first member and the second member, laser welding is performed in a tilted state on the coupling surface of the first member and the second member,
A method of manufacturing a battery module in which a coupling surface of the first member and the second member crosses an extension line in the irradiation direction of the welding irradiation beam. In claim 6,
Further comprising the step of mounting a battery cell stack in which a plurality of battery cells are stacked between the U-shaped frame and the plate-shaped plate,
The welding of the first member and the second member may include welding the plate-shaped plate and the U-shaped frame to each other. In claim 7,
The welding irradiation beam is incident on the U-shaped frame at a shifted position with respect to the coupling surface. In claim 8,
The U-shaped frame includes a bottom portion and two side portions facing each other,
Welding the plate-shaped plate and the U-shaped frame is a battery module manufacturing method for welding the side portion and the plate-shaped plate. In claim 9,
A method of manufacturing a battery module in which one side of the plate-shaped plate adjacent to the coupling surface and an outer surface of the side part are formed side by side. In claim 7,
The U-shaped frame includes a bottom portion and two side portions facing each other,
In the step of welding the plate-shaped plate and the U-shaped frame, the welding process is performed in a state in which the plate-shaped plate is overlapped on the upper end of the side part. In claim 7,
A battery module manufacturing method in which a depression is formed on one side of the plate-shaped plate, and a coupling surface between the plate-shaped plate and the U-shaped frame is formed in the depression. In claim 7,
The step of welding the plate-shaped plate and the U-shaped frame is N _{2 A} method of manufacturing a battery module performed in a gas atmosphere. In claim 7,
The tilting angle is a battery module manufacturing method of 13.5 degrees to 21.5 degrees. 15. In claim 14,
The tilting angle is a battery module manufacturing method of 15 to 20 degrees. In claim 7,
The step of welding the plate-shaped plate and the U-shaped frame includes dual beam laser welding based on a gap between the plate-shaped plate and the U-shaped frame.

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