KR20240082986A - Battery pack and method of manufacturing the same - Google Patents

Abstract

A plurality of battery cells stacked in the first direction in a vertical coordinate system defined by a first direction, a second direction, and a third direction that are perpendicular to each other; and a pack case for storing the battery cells in an internal space, wherein the pack case includes a pair of first outer walls extending in the first direction; a pair of second outer walls extending in the second direction and defining an internal space of the pack case together with the pair of first outer walls; a longitudinal beam extending between the pair of first outer walls and parallel to the first outer walls; and a bottom provided at the bottom of the first outer walls, the second outer walls, and the longitudinal beam, and a wiring structure electrically connected to the plurality of battery cells is provided on the upper part of the longitudinal beam. , a battery pack provided with a heat sink is provided inside the longitudinal beam.

Description

Battery pack and method of manufacturing the same {Battery pack and method of manufacturing the same}

The present invention relates to a battery pack and a method of manufacturing the same, and more specifically, to a battery pack and a method of manufacturing the same that control internal temperature rise and improve safety by quickly removing heat generated inside.

As technology development and demand for various mobile devices, electric vehicles, energy storage systems (ESS), etc. increase significantly, interest in and demand for secondary batteries as an energy source are rapidly increasing. Conventionally, nickel-cadmium batteries or nickel-hydrogen batteries were widely used as secondary batteries, but recently, lithium secondary batteries have almost no memory effect compared to nickel-based secondary batteries, allowing for free charging and discharging, a very low self-discharge rate, and high energy density. Batteries are widely used.

These lithium secondary batteries mainly use lithium-based oxide and carbon material as positive and negative electrode active materials, respectively. A lithium secondary battery includes an electrode assembly in which positive and negative electrode plates coated with the positive and negative electrode active materials are disposed with a separator in between, and an exterior material, that is, a battery case, that seals and stores the electrode assembly together with an electrolyte.

Recently, battery packs have been widely used for driving or energy storage in medium to large-sized devices such as electric vehicles or energy storage systems. A conventional battery pack includes one or more battery modules inside the pack case and a control unit that controls charging and discharging of the battery pack, such as a battery management system (BMS). Here, the battery module is configured to include a plurality of battery cells inside a module case. That is, in the case of a conventional battery pack, a plurality of battery cells (secondary batteries) are stored inside a module case to form each battery module, and one or more of these battery modules are stored inside the pack case to form a battery pack.

In particular, pouch-type batteries have advantages in many aspects, such as being light in weight and requiring less dead space when stacked, but have weaknesses such as being vulnerable to external shocks and having somewhat poor assembly properties. . Therefore, it is common for battery packs to be manufactured by first modularizing a number of cells and then storing them inside a pack case. As a representative example, in the case of a conventional battery pack, a plurality of pouch-type battery cells are first stored inside a module case to form a battery module, and then one or more of these battery modules are stored inside the pack case.

However, such conventional battery packs may be disadvantageous in terms of energy density. Typically, in the process of modularizing a large number of battery cells by storing them inside a module case, the volume of the battery pack may increase unnecessarily or the space occupied by the battery cells may decrease due to various components such as the module case or stacking frame. Furthermore, the space occupied by the components themselves, such as the module case or the stacking frame, as well as the storage space of the battery cells may be reduced to ensure assembly tolerances for these components. Therefore, in the case of conventional battery packs, there may be limitations in increasing energy density.

Additionally, conventional battery packs may be disadvantageous in terms of assembly. In particular, in order to manufacture a battery pack, first, a plurality of battery cells are modularized to form a battery module, and then the battery module is stored in a pack case. Therefore, there is a problem in that the battery pack manufacturing process becomes complicated. Moreover, as disclosed in the prior literature, the process and structure of forming a cell stack using stacking frames, bolts, plates, etc. can be very complicated.

Korean Patent Publication No. 10-2018-0092412

The first technical task to be achieved by the present invention is to provide a battery pack that controls internal temperature rise and improves safety by quickly removing heat generated internally.

The second technical task to be achieved by the present invention is to provide a method of manufacturing a battery pack with improved safety and control of internal temperature rise by quickly removing heat generated internally.

In order to achieve the first technical problem, the present invention includes a plurality of battery cells stacked in the first direction in a vertical coordinate system defined by a first direction, a second direction, and a third direction that are perpendicular to each other; and a pack case for storing the battery cells in an internal space, wherein the pack case includes a pair of first outer walls extending in the first direction; a pair of second outer walls extending in the second direction and defining an internal space of the pack case together with the pair of first outer walls; a longitudinal beam extending between the pair of first outer walls and parallel to the first outer walls; and a bottom provided at the bottom of the first outer walls, the second outer walls, and the longitudinal beam, and a wiring structure electrically connected to the plurality of battery cells is provided on the upper part of the longitudinal beam. , a battery pack provided with a heat sink is provided inside the longitudinal beam.

In some embodiments, the heat sink includes a passage for cooling fluid extending in the first direction.

In some embodiments, an additional heat sink may be further provided in the bottom portion below the plurality of battery cells. In some embodiments, no heat sink may be provided in the bottom of the lower part of the longitudinal beam.

In some embodiments, each of the battery cells includes an electrode assembly, a cover surrounding the electrode assembly, and a first cell lead protruding from one side of the cover to the top of the longitudinal beam in the second direction. can do.

In some embodiments, the first cell lid includes a first portion relatively close to the cover and a second portion relatively spaced further away from the cover, and the second portion is positioned in the first direction. A maximum dimension may be greater than that of the first part, and the second part may be configured as a plane perpendicular to the third direction.

In some embodiments, the wiring structure includes a wiring board extending along an upper surface of the longitudinal beam and a bus bar coupled to the wiring board, and the second portion is welded to the bus bar in the third direction. It can be combined by .

In some embodiments, each of the pair of first outer walls includes an outer wall body extending in the first direction; and a mesa portion protruding from the outer wall body toward neighboring battery cells, and an additional heat sink extending in the first direction may be further provided within the mesa portion.

In some embodiments, the upper surface of the mesa portion is lower than the upper surface of the outer wall body and may have substantially the same height as the upper surface of the longitudinal beam.

In some embodiments, the battery pack may further include an additional wiring structure on the upper surface of the mesa portion.

In some embodiments, a heat sink may not be provided in the bottom of the lower portion of the mesa portion.

In order to achieve the second technical problem, the present invention includes the steps of directly arranging a plurality of battery cells in a pack case in a vertical coordinate system defined by a first direction, a second direction, and a third direction that are perpendicular to each other; and electrically connecting cell leads protruding in the second direction of at least two neighboring battery cells among the plurality of battery cells using a bus bar, wherein the cell leads are connected using a bus bar. The electrically connecting step provides a method of manufacturing a battery pack including connecting each of the cell leads to the bus bar by welding in the third direction. At this time, the pack case includes a pair of first outer walls extending in the first direction; a pair of second outer walls extending in the second direction and defining an internal space of the pack case together with the pair of first outer walls; a longitudinal beam extending between the pair of first outer walls and parallel to the first outer walls; and a bottom provided at the bottom of the first outer walls, the second outer walls, and the longitudinal beam, and a wiring structure electrically connected to the plurality of battery cells is provided on the upper part of the longitudinal beam. , a heat sink may be provided inside the longitudinal beam.

In some embodiments, an additional heat sink may be further provided in the bottom portion below the plurality of battery cells, and no heat sink may be provided in the bottom portion of the lower portion of the longitudinal beam.

In some embodiments, the first cell lid includes a first portion relatively close to the cover and a second portion relatively spaced further away from the cover, and the second portion is positioned in the first direction. A maximum dimension may be greater than that of the first part, and the second part may be configured as a plane perpendicular to the third direction. The wiring structure includes a wiring board extending along an upper surface of the longitudinal beam; And it may include the bus bar coupled on the wiring board.

In some embodiments, each of the pair of first outer walls includes an outer wall body extending in the first direction; and a mesa portion protruding from the outer wall body toward neighboring battery cells, and an additional heat sink extending in the first direction may be further provided within the mesa portion.

The battery pack of the present invention has the effect of controlling internal temperature rise and improving safety by quickly removing heat generated internally.

1 is an exploded perspective view showing main parts of a battery pack according to an embodiment of the present invention.
Figure 2 is a perspective view showing the main portion of the lower case of the pack case according to an embodiment of the present invention.
FIG. 3 is a side cross-sectional view showing the main portion of the battery pack of FIG. 1 cut along line III-III'.
Figure 4 is a perspective view showing main parts of a battery cell according to an embodiment of the present invention.
Figure 5 is a partial enlarged view showing a portion of the battery cell centered on the cell lead portion of the battery cell according to an embodiment of the present invention.
FIG. 6 is an enlarged view of a portion of the battery cell viewed in the x-direction centered on the cell lead portion of the battery cell.
Figure 7 is an enlarged view of a portion of the battery cell viewed from the y direction, centered on the cell lead portion of the battery cell.
Figure 8 is an enlarged view of a portion of the battery cell viewed in the z-direction centered on the cell lead portion of the battery cell.
Figure 9 is a perspective view showing a pair of neighboring battery cells electrically connected by a bus bar.
FIG. 10 is a cross-sectional view showing the second portions and the bus bar of FIG. 9 cut along line XX'.
Figure 11 is a side cross-sectional view showing the main portion of the cross section of a battery pack according to another embodiment of the present invention.
Figure 12 is a flowchart showing a method of manufacturing a battery pack according to an embodiment of the present invention.
Figures 13a and 13b are perspective views showing a method of manufacturing a battery pack according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments of the present invention concept may be modified into various other forms, and the scope of the present invention concept should not be construed as being limited to the embodiments described in detail below. It is preferable that the embodiments of the present invention be interpreted as being provided in order to more completely explain the present invention to a person with average knowledge in the art. Identical symbols refer to identical elements throughout. Furthermore, various elements and areas in the drawings are schematically drawn. Accordingly, the inventive concept is not limited by the relative sizes or spacing depicted in the accompanying drawings.

Terms such as first, second, etc. may be used to describe various components, but the components are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, a first component may be named a second component, and conversely, a second component may be named a first component without departing from the scope of the inventive concept.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the inventive concept. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, expressions such as “comprises” or “has” are intended to indicate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features or It should be understood that this does not preclude the presence or addition of numbers, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical terms and scientific terms, have the same meaning as commonly understood by those skilled in the art in the technical field to which the concept of the present invention pertains. Additionally, commonly used terms, as defined in dictionaries, should be interpreted to have meanings consistent with what they mean in the context of the relevant technology, and should not be used in an overly formal sense unless explicitly defined herein. It will be understood that this is not to be interpreted.

If an embodiment can be implemented differently, a specific process sequence may be performed differently from the described sequence. For example, two processes described in succession may be performed substantially at the same time, or may be performed in an order opposite to the order in which they are described.

In the accompanying drawings, variations of the depicted shape may be expected, for example, depending on manufacturing techniques and/or tolerances. Accordingly, embodiments of the present invention should not be construed as being limited to the specific shape of the area shown in this specification, but should include, for example, changes in shape that occur during the manufacturing process. As used herein, any term “and/or” includes each and every combination of one or more of the mentioned elements. Additionally, the term “substrate” used in this specification may refer to the substrate itself or a laminated structure including the substrate and a predetermined layer or film formed on the surface. Additionally, in this specification, the term “surface of the substrate” may mean the exposed surface of the substrate itself, or the outer surface of a predetermined layer or film formed on the substrate.

Figure 1 is an exploded perspective view showing main parts of the battery pack 10 according to an embodiment of the present invention. In FIG. 1, the battery pack 10 is shown as being defined in a vertical coordinate system defined by a first direction along the x-axis, a second direction along the y-axis, and a third direction along the z-axis while being perpendicular to each other, the first direction , the second direction, and the third direction are not particularly limited as long as they are relatively perpendicular to each other.

Referring to FIG. 1, the battery pack 10 includes a plurality of battery cells 100 stacked in a first direction (e.g., x-axis direction) and a pack case 300 that accommodates the plurality of battery cells 100. ) includes.

The pack case 300 has an internal space 330 that can accommodate the plurality of battery cells 100. In some embodiments, the pack case 300 may include an upper case 310 and a lower case 320 that define the internal space 330.

Although not explicitly shown in FIG. 1 , the pack case 300 may be provided with a conductive wire that electrically connects the plurality of battery cells 100 to an external electric load.

In some embodiments, the lower case 320 may have a box shape with an open top and may accommodate a plurality of battery cells 100 in the internal space 330. Additionally, the upper case 310 may be configured in the form of a cover that covers the upper opening of the lower case 320. In some embodiments, the upper case 310 may be configured as a box with an open bottom.

The pack case 300 may include plastic or metal material. In addition, the pack case 300 may employ various exterior materials of battery packs known at the time of filing the present invention.

The battery pack 10 may further include a battery management system. A battery management system (BMS) is mounted in the internal space of the pack case 300 and may be configured to generally control charging and discharging operations and data transmission and reception operations of the battery cell 100. The battery management system may be provided on a pack basis rather than a module basis. More specifically, the battery management system may be configured to control the charge/discharge state, power state, and performance state of the battery cell 100 through pack voltage and pack current.

The battery pack 10 may further include a battery cut-off unit. The battery disconnect unit (BDU) may be configured to control the electrical connection of battery cells to manage the power capacity and function of the battery pack 10. To this end, the battery blocking unit may include a power relay, a current sensor, a fuse, etc. The battery blocking unit is also provided in a pack unit rather than a module unit, and various blocking units known at the time of filing the application of the present invention may be employed.

In addition, the battery pack 10 may further include various battery pack components known at the time of filing the present invention. For example, the battery pack 10 according to an embodiment of the present invention may further include a manual service disconnector (MSD) that allows an operator to cut off power by manually disconnecting the service plug.

Figure 2 is a perspective view showing the main portion of the lower case 320 of the pack case 300 according to an embodiment of the present invention.

Referring to FIG. 2, the lower case 320 includes a pair of first outer walls 321 extending in the first direction (eg, x-axis direction). In addition, the lower case 320 extends in the second direction (for example, the y-axis direction) and forms the inner space 330 of the pack case 300 together with the pair of first outer walls 321. It includes a pair of second outer walls 322 defining . In some embodiments, the first outer walls 321 and the second outer walls 322 may be formed as one body.

The lower case 320 further includes a longitudinal beam 323 extending between the pair of first outer walls 321 and parallel to the first outer walls 321 . The longitudinal beam 323 may extend in the first direction (eg, x-axis direction) and meet the pair of second outer walls 322. In some embodiments, the longitudinal beam 323 may be formed integrally with the second outer walls 322.

In some embodiments, the longitudinal beam 323 may have a mesa structure. In some embodiments, the top surface of the longitudinal beam 323 may be lower than the top surface of the second outer walls 322. In some embodiments, the sidewall of the longitudinal beam 323 may extend obliquely downward with respect to its upper surface. In some other embodiments, the sidewall of the longitudinal beam 323 may extend perpendicular to its upper surface. In some embodiments, the sidewall of the longitudinal beam 323 may be configured to correspond to the edge shape of the neighboring battery cell 100.

The longitudinal beam 323, together with the neighboring first outer wall 321 of the first outer walls 321, defines an internal space 330 in which battery cells 100 (see FIG. 1) can be accommodated. You can.

In some embodiments, the lower case 320 may include two or more longitudinal beams 323. In some embodiments, the pack case 300 may include two or more longitudinal beams 323. When the lower case 320 includes two or more longitudinal beams 323, the two neighboring longitudinal beams 323 form an internal space 330 in which battery cells 100 (see FIG. 1) can be accommodated. can be defined.

FIG. 3 is a side cross-sectional view showing the main portion of the battery pack 10 of FIG. 1 cut along line III-III'.

2 and 3, each of the pair of first outer walls 321 includes an outer wall body 3211 extending in the first direction (for example, the x-axis direction) and an outer wall body 3211 It may include a mesa portion 3212 protruding from the outer wall body 3211 toward the neighboring battery cells 100.

The mesa portion 3212 may extend in the first direction (eg, x-axis direction) and meet the pair of second outer walls 322. In some embodiments, the mesa portion 3212 may be formed integrally with the outer wall body 3211 and/or the second outer walls 322.

The upper surface of the mesa portion 3212 may be lower than the upper surface of the second outer walls 322. In some embodiments, the top surface of the mesa portion 3212 may be coplanar with the top surface of the longitudinal beam 323. In some embodiments, the width of the upper surface of the mesa portion 3212 may be narrower than the width of the upper surface of the longitudinal beam 323.

In some embodiments, the sidewall of the mesa portion 3212 may extend obliquely downward with respect to its upper surface. In some other embodiments, the sidewall of the mesa portion 3212 may extend perpendicular to its upper surface. In some embodiments, the sidewall of the mesa portion 3212 may be configured to correspond to the edge shape of the neighboring battery cell 100.

A wiring structure 350 may be provided on the upper surface of the longitudinal beam 323. The wiring structure 350 may be any structure that electrically connects the battery cells 100. In some embodiments, the wiring structure 350 may include a wiring board 352 extending in the first direction (eg, x-axis direction) along the longitudinal beam 323. The wiring board 352 may include an insulating layer and arbitrary conductive lines formed on the insulating layer.

In some embodiments, the wiring structure 350 may further include bus bars 200 on the wiring board 352.

The bus bar 200 may be any conductor that electrically connects two neighboring battery cells 100 in the first direction (eg, x-axis direction). This will be explained in more detail later.

A heat sink 3251 penetrating the longitudinal beam 323 in the first direction (eg, x-axis direction) may be provided within the longitudinal beam 323. For example, the heat sink 3251 may be a passage for cooling fluid extending in the first direction (eg, x-axis direction). The cooling fluid may be liquid, gas, or a mixture thereof. For example, the cooling fluid may be water, air, alcohol, nitrogen, etc., but is not limited to these.

As shown in FIG. 3, the cell leads 110 of the battery cells 100 are coupled to the bus bar 200 at the top of the longitudinal beam 323, and the cell leads 110 are connected to the bus bar 200 during operation of the battery pack 10. A large amount of heat is generated where the field 110 and the bus bar 200 are combined. Therefore, the heat sink 3251 penetrating the inside of the longitudinal beam 323 can quickly remove a large amount of generated heat, thereby controlling the temperature rise of the battery pack 10 and ensuring the safety of the battery pack 10. can be improved.

The heat sink 3251 may be connected to be in fluid communication with a cooling fluid reservoir provided outside the pack case 300. In some embodiments, the cooling fluid reservoir may be configured to cool fluid stored therein.

In some embodiments, the wiring structure 350 may also be provided on the upper surface of the mesa portion 3212 of the first outer walls 321. The wiring structure 350 on the mesa portion 3212 may also include a wiring board 352 and bus bars 200.

A heat sink 3252 penetrating the mesa portion 3212 in the first direction (eg, x-axis direction) may be provided within the mesa portion 3212. For example, the heat sink 3252 may be a passage for cooling fluid extending in the first direction (eg, x-axis direction). The cooling fluid may be liquid, gas, or a mixture thereof. For example, the cooling fluid may be water, air, alcohol, nitrogen, etc., but is not limited to these.

In some embodiments, the cell leads 110 of the battery cells 100 are coupled to the bus bar 200 at the top of the mesa portion 3212, and the cell leads 110 are connected to the bus bar 200 during operation of the battery pack 10. A large amount of heat is generated where (110) and the bus bar (200) are combined. Therefore, the heat sink 3252 penetrating the inside of the mesa portion 3212 can quickly remove a large amount of generated heat, thereby controlling the temperature rise of the battery pack 10 and ensuring the safety of the battery pack 10. It can be improved.

The heat sink 3252 may be connected to be in fluid communication with a cooling fluid reservoir provided outside the pack case 300. In some embodiments, the cooling fluid reservoir may be configured to cool fluid stored therein.

The lower case 320 further includes a bottom portion 326. The bottom portion 326 is provided at the lower portion of the pair of first outer walls 321, the pair of second outer walls 322, and the longitudinal beam 323. In some embodiments, the bottom portion 326 includes one or more of the pair of first exterior walls 321, the pair of second exterior walls 322, and the longitudinal beam 323. It can be composed as a whole.

In some embodiments, an additional heat sink 3253 may be further provided in the bottom portion 326 below the battery cells 100. For example, the additional heat sink 3253 may be a cooling fluid passage extending in the first direction (eg, x-axis direction). The cooling fluid may be liquid, gas, or a mixture thereof. For example, the cooling fluid may be water, air, alcohol, nitrogen, etc., but is not limited to these.

The additional heat sink 3253 can quickly remove heat generated during charging and discharging of the battery cells 100, thereby controlling the temperature rise of the battery pack 10 and improving the safety of the battery pack 10. You can do it.

In some embodiments, no heat sink may be provided in the bottom 326 of the lower part of the longitudinal beam 323. In some embodiments, a heat sink may not be provided in the bottom portion 326 below the mesa portion 3212.

Figure 4 is a perspective view showing main parts of the battery cell 100 according to an embodiment of the present invention.

Referring to FIG. 4, the battery cell 100 includes an electrode assembly 101, a cover 105 surrounding the electrode assembly 101, and a battery cell 100 extending from one side of the cover 105 in the second direction (e.g. , y direction) and includes a cell lead 110 protruding.

In some embodiments, the battery cell 100 may be a pouch-type battery cell, but the present invention is not limited thereto. In some embodiments, the battery cell 100 may be a prismatic battery cell.

In some embodiments, the battery cell 100 has a thin plate-shaped body and may preferably have a pouch cell structure. The pouch cell may have a structure in which an anode, a separator, and a cathode are alternately stacked to form the electrode assembly 101, and an electrode tab is drawn out at least on one side and connected to the cell lead 110. The positive and negative electrodes can be manufactured by applying a slurry of electrode active material, binder resin, conductive agent, and other additives to at least one side of the current collector. In the case of the positive electrode, a typical positive electrode active material such as a lithium-containing transition metal oxide may be used, and in the case of the negative electrode, lithium metal, carbon material, and a metal compound that can occlude and release lithium ions, or a mixture thereof. Common anode active materials such as can be used. Additionally, a typical porous polymer film used in lithium secondary batteries can be used as the separator.

The electrolyte solution contained in the cover 105 together with the electrode assembly 101 may be a typical electrolyte solution for lithium secondary batteries. The cover 105 is made of a sheet material and has a receiving portion for accommodating the electrode assembly 101. Preferably, the cover 105 is formed by combining a first case and a second case, which are formed by processing a sheet material into a predetermined shape. The sheet material that makes up the cover 105 includes an outermost outer resin layer made of an insulating material such as polyethylene terephthalate (PET) or nylon, and a material that maintains mechanical strength and prevents moisture and oxygen from penetrating. It consists of a multi-layer structure in which a metal layer made of aluminum and an internal resin layer made of a polyolefin-based material that has heat adhesive properties and serves as a sealing material are laminated.

The sheet material forming the cover 105 may have a predetermined adhesive resin layer interposed between the inner resin layer and the metal layer, and the outer resin layer and the metal layer, as needed. The adhesive resin layer is for smooth adhesion between different materials and is formed as a single layer or multilayer. The material is usually polyolefin resin, or polyurethane resin can be used for smooth processing, and mixtures of these can also be employed. .

As shown in FIG. 4 , the battery cell 100 has two main surfaces S1 and S2 perpendicular to the first direction (eg, x direction). That is, the battery cell 100 may have a first main surface S1 and a second main surface S2 that extend along the yz plane of FIG. 4 and are parallel to each other.

FIG. 5 is an enlarged view of a portion of the battery cell 100 centered on the cell lead 110 of the battery cell 100 according to an embodiment of the present invention.

Referring to FIG. 5, the cell lead 110 protrudes from one side of the cover 105 in the second direction (e.g., y-axis direction) and includes a first part 111 and a second part 112. Includes. The first part 111 may be located relatively closer to the cover 105 than the second part 112. Additionally, the second portion 112 may be the leading edge of the cell lead 110 in the second direction.

The first part 111 and the second part 112 may be electrically connected to each other. In some embodiments, the first part 111 and the second part 112 may be in direct contact with each other, but the present invention is not limited thereto. In some embodiments, the first part 111 and the second part 112 may be integrated.

In some embodiments, the first part 111 may have a flat plate shape with a main plane being a plane perpendicular to the first direction (eg, x-axis direction). In some embodiments, the second part 112 may be configured as a plane perpendicular to the third direction (eg, z-axis direction). Here, the fact that the second part 112 is composed of a plane perpendicular to the third direction means that the upper and lower surfaces of the second part 112 are perpendicular to the third direction and are within the upper and lower surfaces. This means that it does not include through holes. In some embodiments, the upper and lower surfaces of the second portion 112 may be perpendicular to the third direction and may not include through holes in the upper and lower surfaces. In some embodiments, the upper and lower surfaces of the second portion 112 may be perpendicular to the third direction and may include through holes in the upper and lower surfaces.

FIG. 6 is an enlarged view of a portion of the battery cell 100 viewed in the x direction, centered on the cell lead 110 of the battery cell 100.

Referring to FIG. 6, the first portion 111 of the cell lead 110 has a first upper surface 111a and a first lower surface 111b. Additionally, the second portion 112 of the cell lead 110 has a second upper surface 112a and a second lower surface 112b. Here, 'top' and 'bottom' are relative concepts, and the thing located relatively above can be defined as 'top', and the thing located relatively below can be defined as 'bottom', and one of them is called 'top' and the other is 'bottom'. It can also be defined as ‘if you do it’.

A center line CL may be defined for the first portion 111. The center line CL is a straight line in the second direction (eg, y-axis direction) that divides the first portion 111 into two in the third direction (eg, z-axis direction).

In the third direction, the center line CL may be located between the second upper surface 112a and the second lower surface 112b of the second portion 112.

In the third direction, the first part 111 has a first dimension H1 and the second part 112 has a second dimension H2 that is smaller than the first dimension H1. The second dimension H2 may be, for example, about 0.5% to about 50% of the first dimension H1. In some embodiments, the second dimension (H2) is about 0.5% to about 50%, about 1% to about 48%, about 1.5% to about 45%, about 2% of the first dimension (H1). to about 43%, about 2.5% to about 40%, about 3% to about 38%, about 3.5% to about 35%, about 4% to about 33%, about 4.5% to about 30%, about 5% to about 28%, about 5.5% to about 25%, about 6% to about 23%, about 6.5% to about 20%, about 7% to about 18%, about 7.5% to about 15%, about 8% to about 13% , from about 8.5% to about 10%, or between any two of these values.

If the second dimension H2 is too small compared to the first dimension H1, the mechanical strength of the second part 112 may be insufficient and may be easily damaged. If the second dimension H2 is too large compared to the first dimension H1, the weight of the battery cell 100 may unnecessarily increase.

FIG. 7 is an enlarged view of a portion of the battery cell 100 viewed from the y direction, centered on the cell lead 110 of the battery cell 100.

Referring to FIG. 7, the first portion 111 of the cell lead 110 in a first direction (e.g., x-axis direction) has a first maximum dimension d1, and the cell lead 110 The second portion 112 of has a second maximum dimension d2. The second maximum dimension d2 is larger than the first maximum dimension d1. For example, the second maximum dimension d2 may be about 2 to about 20 times the first maximum dimension d1. In some embodiments, the second maximum dimension d2 is about 2 times to about 20 times, about 2.5 times to about 19.5 times, about 3 times to about 19 times, about 3.5 times to about 18.5 times, about 4 times to about 18 times, about 4.5 times to about 17.5 times, about 5 times to about 17 times, about 5.5 times to about 16.5 times, about 6 times to about 16 times, about 6.5 times to about 15.5 times, about 7 times to about 15 times, about 7.5 times to about 14.5 times, about 8 times to about 14 times, about 8.5 times to about 13.5 times, about 9 times to about 13 times, about 9.5 times to about 12.5 times, about 10 times to about 12 times, about 10.5 times to about 11.5 times, or between any two of these values.

If the second maximum dimension d2 is too small compared to the first maximum dimension d1, it may not be easy to weld the second portion 112 with a bus bar, which will be described later. If the second maximum dimension (d2) is too large compared to the first maximum dimension (d1), the thickness of the battery cell 100 in the first direction (for example, x-axis direction) increases excessively, thereby reducing the energy density. may deteriorate.

In some embodiments, the second maximum dimension d2 of the second portion 112 in the first direction (e.g., x-axis direction) is greater than or equal to the first main surface S1 of the battery cell 100. ) and the second main surface (S2) may be larger than the cell thickness (d3) defined between. In some other embodiments, the second maximum dimension d2 of the second portion 112 in the first direction (e.g., x-axis direction) is the first main surface of the battery cell 100 ( It may be smaller than the cell thickness d3 defined between S1) and the second main surface S2.

FIG. 8 is an enlarged view of a portion of the battery cell 100 viewed in the z direction, centered on the cell lead 110 of the battery cell 100.

Referring to FIG. 8, the projection of the second portion 112 on a plane (e.g., xy plane) perpendicular to the third direction (e.g., z-axis direction) may have a circular shape. there is. In some embodiments, the projection of the second portion 112 on the xy plane may have an oval, a polygon (eg, a square, a pentagon, a hexagon, etc.), or any other shape other than a circle. However, it may be advantageous for the projection to have a circular shape in terms of diversity of welding methods that can be used for welding with bus bars in the future, structural stability, ease of handling, etc.

In some embodiments, when the projection is circular, the second portion 112 may have the shape of a cylinder or truncated cone. When the projection is a polygon, the second portion 112 may have the shape of a polygonal prism or polygonal pyramid.

The projected area of the second part 112 may be about 2 to about 20 times the projected area of the first part 111. In some embodiments, the projected area of the second portion 112 is about 2 to about 20 times, about 2.5 to about 19 times, or about 3 times the projection area of the first portion 111. to about 18 times, about 3.5 times to about 17 times, about 4 times to about 16 times, about 4.5 times to about 15 times, about 5 times to about 14 times, about 5.5 times to about 13 times, about 6 times to about 12 times, about 6.5 times to about 11 times, about 7 times to about 10 times, about 7.5 times to about 9 times, or between any two of these values.

If the projected area of the second part 112 is too small compared to the projected area of the first part 111, welding the bus bar and the second part 112, which will be described later, may not be easy. If the projected area of the second part 112 is too large compared to the projected area of the first part 111, the weight of the battery cell 100 may unnecessarily increase.

The battery cells 100 are stored in the pack case 300 because the second portion 112 of the cell lead 110 has a planar shape perpendicular to the third direction (for example, z-axis direction). ), it is possible to electrically interconnect them. Therefore, battery packs according to embodiments of the present invention can be manufactured inexpensively due to a simple number of parts, have excellent productivity, and have low risk of product failure.

FIG. 9 is a perspective view showing a pair of neighboring battery cells 100_1 and 100_2 electrically connected by the bus bar 200.

Referring to FIG. 9, the cell lead 110_1 of the first battery cell 100_1 includes a first part 111_1 and a second part 112_1, and the cell lead 110_2 of the second battery cell 100_2 includes a first part (111_2) and a second part (112_2).

The cell lead 110_1 of the first battery cell 100_1 and the cell lead 110_2 of the second battery cell 100_2 may be electrically connected by a bus bar 200. Specifically, the second part 112_1 of the first battery cell 100_1 and the second part 112_2 of the second battery cell 100_2 may be electrically connected to the bus bar 200.

The cell lead 110_1 of the first battery cell 100_1 and the cell lead 110_2 of the second battery cell 100_2, which are electrically connected by the bus bar 200, may have the same polarity or may have different polarities. It may have polarity.

The bus bar 200 may be arranged to extend in a first direction (for example, the It may be configured to contact the lower surfaces of each of the two parts (112_2). In some embodiments, the bus bar 200 may have a strip shape extending in a first direction. At this time, the flat surface of the bus bar 200 is aligned with the second part 112_1 of the first battery cell 100_1 and the second part 112_2 of the second battery cell 100_2 in a third direction (for example For example, it can be faced in the z-axis direction).

The bus bar 200 may be provided on a wiring board 352 disposed on top of the longitudinal beam 323, as described with reference to FIGS. 2 and 3. In some embodiments, the bus bar 200 may be provided on the wiring board 352 disposed on the mesa portion 3212, as described with reference to FIGS. 2 and 3.

The cell lead 110_1 of the first battery cell 100_1 and the cell lead 110_2 of the second battery cell 100_2 may extend to the top of the longitudinal beam 323. Specifically, the cell lead 110_1 of the first battery cell 100_1 and the cell lead 110_2 of the second battery cell 100_2 are electrically connected to the bus bar 200 at the top of the longitudinal beam 323. It can be connected to .

FIG. 10 is a cross-sectional view showing the second portions 112_1 and 112_2 and the bus bar 200 of FIG. 9 taken along the line X-X'.

Referring to FIG. 10, the bus bar 200 may have a recess R concave in a third direction (for example, z-axis direction) at a portion overlapping the second portions 112_1 and 112_2. . In some embodiments, the recess R may be created as a result of welding the bus bar 200 and the second parts 112_1 and 112_2 in a third direction. However, since the recess R is a result of the contact area between the bus bar 200 and the second parts 112_1 and 112_2 being partially melted and solidified by welding, melting and solidification may occur in some cases. It may appear as a trace of .

In FIG. 10, the recess (R) is shown to be formed continuously with the flat surface of the bus bar 200, but in some cases, a slight ridge may be formed around the recess (R).

In some embodiments, depending on the welding method, the recess R may not be identified as a clear interface.

Figure 11 is a side cross-sectional view showing the main portion of the cross section of the battery pack 10 according to another embodiment of the present invention.

Referring to FIG. 11 , in some embodiments, an additional heat sink may also be provided within the bottom portion 326 of the lower portion of the longitudinal beam 323. In some embodiments, an additional heat sink may also be provided in the bottom portion 326 below the mesa portion 3212. By providing additional heat sink(s) in this way, heat generated in the area where the cell lead and the bus bar 200 are joined can be more quickly removed.

Figure 12 is a flowchart showing a manufacturing method of the battery pack 10 according to an embodiment of the present invention. Figures 13a and 13b are perspective views showing a method of manufacturing the battery pack 10 according to an embodiment of the present invention.

Referring to FIGS. 12 and 13A , a plurality of battery cells 100 can be directly placed in the pack case 300 (S10). Here, placing the plurality of battery cells 100 directly in the pack case 300 means placing the plurality of battery cells 100 in the pack case 300 without configuring them as modules.

In some embodiments, the plurality of battery cells 100 may be individually disposed in the pack case 300 one by one. In some other embodiments, two or more of the plurality of battery cells 100 may be stacked and then placed in the pack case 300.

The method of placing the battery cells 100 in the pack case 300 is not particularly limited, and the battery cells 100 may be placed in the pack case 300 by any known method. Since the configuration of the pack case 300 has been described with reference to FIGS. 2 and 3, detailed description will be omitted here. In addition, since the specific configuration of each battery cell 100 has been described with reference to FIGS. 4 to 10, detailed description will be omitted here.

Referring to FIGS. 12 and 13B, the cell leads 110_1 and 110_2 protruding in the second direction (e.g., y-axis direction) of the two neighboring battery cells 100 are electrically connected to the bus bar 200. (S20). The cell leads 110_1 and 110_2 may be connected to the bus bar 200 by welding in a third direction (eg, z-axis direction).

In some embodiments, the bus bar 200 may already be disposed in the pack case 300 before the plurality of battery cells 100 are disposed in the pack case 300. In some embodiments, the bus bar 200 may be disposed on the cell leads 110_1 and 110_2 after the plurality of battery cells 100 are disposed in the pack case 300. Thereafter, the bus bar 200 may be welded to the cell leads 110_1 and 110_2. The welding method may be any known method and is not particularly limited.

The battery cells 100 are stored in the pack case 300 because the second portion 112 of the cell lead 110 has a planar shape perpendicular to the third direction (for example, z-axis direction). ), it is possible to electrically interconnect them. Therefore, battery packs according to embodiments of the present invention can be manufactured inexpensively due to a simple number of parts, have excellent productivity, and have low risk of product failure.

As discussed above, the embodiments of the present invention have been described in detail, but those skilled in the art will understand that without departing from the spirit and scope of the present invention as defined in the appended claims, The present invention may be implemented with various modifications. Therefore, changes in future embodiments of the present invention will not depart from the scope of the present invention.

10: battery pack 100: battery cell
101: electrode assembly 105: cover
110: cell lead 111: first part
111a: first upper surface 111b: first lower surface
112: second part 112a: second upper surface
112b: second lower surface 200: bus bar
300: pack case 310: upper case
320: lower case 321: first outer wall
3211: External wall body 3212: Mesa part
322: second outer wall 323: longitudinal beam
3251, 3252, 3253: heat sink 326: bottom
330: internal space 350: wiring structure
352: Wiring board CL: Center line
S1, S2: main surface

Claims (15)

In a vertical coordinate system defined by a first direction, a second direction, and a third direction perpendicular to each other,
a plurality of battery cells stacked in the first direction; and
a pack case storing the battery cells in an internal space;
Including,
The pack case includes:
a pair of first outer walls extending in the first direction;
a pair of second outer walls extending in the second direction and defining an internal space of the pack case together with the pair of first outer walls;
a longitudinal beam extending between the pair of first outer walls and parallel to the first outer walls; and
a bottom provided at a lower portion of the first outer walls, the second outer walls, and the longitudinal beam;
Including,
A wiring structure electrically connected to the plurality of battery cells is provided on the upper part of the longitudinal beam,
A battery pack provided with a heat sink inside the longitudinal beam. According to claim 1,
The battery pack, wherein the heat sink includes a cooling fluid passage extending in the first direction. According to claim 2,
A battery pack, characterized in that an additional heat sink is further provided in the bottom portion below the plurality of battery cells. According to claim 3,
Battery pack, characterized in that no heat sink is provided in the bottom of the lower part of the longitudinal beam. According to claim 1,
Each of the battery cells includes an electrode assembly, a cover surrounding the electrode assembly, and a first cell lead protruding from one side of the cover to the top of the longitudinal beam in the second direction. . According to claim 5,
The first cell lid includes a first portion relatively close to the cover and a second portion relatively spaced further away from the cover,
A battery pack, characterized in that the maximum dimension of the second portion in the first direction is larger than the maximum dimension of the first portion, and the second portion is configured as a plane perpendicular to the third direction. According to claim 5,
The wiring structure is:
a wiring board extending along the upper surface of the longitudinal beam; and
a bus bar coupled to the wiring board;
Including,
The battery pack, wherein the second part is joined to the bus bar by welding in the third direction. According to claim 1,
Each of the pair of first outer walls:
an outer wall body extending in the first direction; and
a mesa portion protruding from the outer wall body toward neighboring battery cells;
Including,
The battery pack, characterized in that an additional heat sink extending in the first direction is further provided within the mesa portion. According to claim 8,
The battery pack, wherein the upper surface of the mesa portion is lower than the upper surface of the outer wall body and has substantially the same height as the upper surface of the longitudinal beam. According to claim 8,
A battery pack further comprising an additional wiring structure on the upper surface of the mesa portion. According to claim 8,
A battery pack, characterized in that a heat sink is not provided in the bottom of the lower portion of the mesa portion. In a vertical coordinate system defined by a first direction, a second direction, and a third direction perpendicular to each other,
Placing a plurality of battery cells directly into a pack case; and
electrically connecting cell leads protruding in the second direction of at least two neighboring battery cells among the plurality of battery cells using a bus bar;
Including,
The step of electrically connecting the cell leads using a bus bar includes connecting each of the cell leads to the bus bar by welding in the third direction,
The pack case includes:
a pair of first outer walls extending in the first direction;
a pair of second outer walls extending in the second direction and defining an internal space of the pack case together with the pair of first outer walls;
a longitudinal beam extending between the pair of first outer walls and parallel to the first outer walls; and
a bottom provided at a lower portion of the first outer walls, the second outer walls, and the longitudinal beam;
Including,
A wiring structure electrically connected to the plurality of battery cells is provided on the upper part of the longitudinal beam,
A method of manufacturing a battery pack in which a heat sink is provided inside the longitudinal beam. According to claim 12,
An additional heat sink is further provided in the bottom portion of the lower portion of the plurality of battery cells, and no heat sink is provided in the bottom portion of the lower portion of the longitudinal beam. According to claim 12,
The first cell lid includes a first portion relatively close to the cover and a second portion relatively spaced further away from the cover,
The maximum dimension of the second part in the first direction is larger than the maximum dimension of the first part, and the second part is configured as a plane perpendicular to the third direction,
The wiring structure is:
a wiring board extending along the upper surface of the longitudinal beam; and
the bus bar coupled to the wiring board;
A method of manufacturing a battery pack comprising: According to claim 14,
Each of the pair of first outer walls:
an outer wall body extending in the first direction; and
a mesa portion protruding from the outer wall body toward neighboring battery cells;
Including,
A method of manufacturing a battery pack, characterized in that an additional heat sink extending in the first direction is further provided within the mesa portion.

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