Battery pack and method for manufacturing the same

Abstract

In a vertical coordinate system defined by a first direction, a second direction, and a third direction perpendicular to each other, a battery pack is provided that includes a plurality of battery cells stacked in the first direction and a pack case that houses the battery cells in an interior space, the pack case including 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 interior space of the pack case together with the pair of first outer walls, longitudinal beams extending between the pair of first outer walls and parallel to the first outer walls, and a bottom provided at lower parts of the first outer walls, the second outer walls, and the longitudinal beams, wherein a wiring structure electrically connected to the plurality of battery cells is provided at an upper part of the longitudinal beam, and a heat sink is provided inside the longitudinal beam.

Description

Technical Field

[0001] The present invention relates to a battery pack and a method for manufacturing the same, and more specifically, to a battery pack and a method for manufacturing the same, which control the rise in internal temperature by rapidly removing heat generated inside, thereby improving safety.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0167136 filed on December 2, 2022 and Korean Patent Application No. 10-2023-0038228 filed on March 23, 2023, and all the contents disclosed in the documents of the Korean patent applications are included as part of this specification.

Background Art

[0003] As the technology development and demand for various mobile devices, electric vehicles, energy storage systems (ESS), etc. have increased significantly, the interest and demand for secondary batteries as an energy source have been rapidly increasing. Conventionally, nickel-cadmium batteries or nickel-metal hydride batteries have been widely used as secondary batteries. However, in recent years, lithium secondary batteries that hardly cause a memory effect compared to nickel-based secondary batteries, can be freely charged and discharged, have a very low self-discharge rate, and have a high energy density have been widely used.

[0004] Such lithium secondary batteries mainly use a lithium-based oxide and a carbon material as a positive electrode active material and a negative electrode active material, respectively. A lithium secondary battery includes an electrode assembly in which a positive electrode plate and a negative electrode plate coated with such a positive electrode active material and a negative electrode active material are arranged with a separator interposed therebetween, and an exterior material that hermetically stores the electrode assembly together with an electrolytic solution, that is, a battery case.

[0005] In recent years, battery packs have been widely used in medium- and large-scale devices such as electric vehicles and energy storage systems for propulsion and energy storage. Conventional battery packs include one or more battery modules and a control unit, such as a BMS (battery management system), which controls the charging and discharging of the battery pack, inside a pack case. Here, the battery module is configured to contain a large number of battery cells inside a module case. In other words, in the case of a conventional battery pack, a large number of battery cells (secondary batteries) are housed inside a module case to constitute each battery module, and such battery modules are housed inside one or more pack cases to constitute a battery pack.

[0006] In particular, pouch-type batteries have advantages in various aspects, such as being lightweight and having less dead space when stacked, but they also have weaknesses, such as being vulnerable to external impacts and having somewhat reduced ease of assembly. Therefore, it is common for battery packs to be manufactured in a form in which a large number of cells are first modularized and then housed inside a pack case. A typical example is a conventional battery pack, in which a large number of pouch-type battery cells are first housed inside a module case to form a battery module, and then these battery modules are housed inside one or more pack cases.

[0007] However, conventional battery packs may have disadvantages in terms of energy density. Typically, in the process of modularizing a large number of battery cells by housing them inside a module case, the volume of the battery pack may unnecessarily increase 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 stacking frame, may be reduced, and the space for housing the battery cells may also decrease in order to ensure assembly tolerances for these components. Therefore, conventional battery packs may have limitations in increasing energy density.

[0008] Furthermore, conventional battery packs may also be disadvantageous in terms of assembly. In particular, manufacturing a battery pack involves first modularizing numerous battery cells to form battery modules, and then housing these battery modules in a pack case, which complicates the manufacturing process. Moreover, as disclosed in the aforementioned prior art, the process and structure for forming the cell stack using a stacking frame, bolts, plates, etc., can be extremely complex. [Overview of the project] [Problems that the invention aims to solve]

[0009] The first technical problem that the present invention aims to solve is to provide a battery pack with improved safety by controlling the rise in internal temperature by rapidly removing the heat generated inside.

[0010] The second technical problem that the present invention aims to solve is to provide a method for manufacturing a battery pack that controls the rise in internal temperature by rapidly removing the heat generated inside, thereby improving safety. [Means for solving the problem]

[0011] To achieve the first technical objective described above, the present invention provides a battery pack comprising a plurality of battery cells stacked in the first direction in a vertical coordinate system defined as a first, second, and third direction perpendicular to each other, and a pack case housing the battery cells in its internal space, wherein the pack case comprises a pair of first outer walls extending in the first direction, a pair of second outer walls extending in the second direction and defining the 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 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, wherein a wiring structure electrically connected to the plurality of battery cells is provided at the top of the longitudinal beam, and a heat sink is provided inside the longitudinal beam.

[0012] In some embodiments, the heat sink includes a passage for a cooling fluid extending in the first direction.

[0013] In some embodiments, additional heat sinks may be provided within the bottom of the lower part of the plurality of battery cells. In some embodiments, no heat sink may be provided within the bottom of the lower part of the longitudinal beam.

[0014] In some embodiments, each of the battery cells may include an electrode assembly, a cover surrounding the electrode assembly, and a first cell lead protruding from one side of the cover in the second direction to the top of the longitudinal beam.

[0015] In some embodiments, the first cell lead includes a first portion relatively close to the cover and a second portion relatively further away from the cover, wherein in the first direction, the maximum dimension of the second portion is even greater than the maximum dimension of the first portion, and the second portion may be composed of a plane perpendicular to the third direction.

[0016] In some embodiments, the wiring structure includes a wiring board extending along the upper surface of the longitudinal beam and a busbar coupled to the wiring board, wherein the second portion may be coupled to the busbar by welding in the third direction.

[0017] 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 projecting from the outer wall body toward an adjacent battery cell, and an additional heat sink extending in the first direction may be provided within the mesa portion.

[0018] In some embodiments, the upper surface of the mesa portion may be lower than the upper surface of the outer wall body and at the same height as the upper surface of the vertical beam.

[0019] In some embodiments, the battery pack may further include additional wiring structures on the upper surface of the mesa portion.

[0020] In some embodiments, a heat sink may not be provided in the bottom of the lower part of the mesa section.

[0021] To achieve the second technical objective described above, the present invention provides a method for manufacturing a battery pack that includes the steps of: directly arranging a plurality of battery cells in a pack case in a vertical coordinate system defined as a first direction, a second direction, and a third direction perpendicular to each other; and electrically connecting the cell leads of at least two adjacent battery cells among the plurality of battery cells that protrude in the second direction using a bus bar, wherein the step of electrically connecting the cell leads using a bus bar includes the step of welding each of the cell leads to the bus bar in the third direction. In this case, 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 the 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, wherein a wiring structure electrically connected to the plurality of battery cells is provided at the top of the longitudinal beam, and a heat sink may be provided inside the longitudinal beam.

[0022] In some embodiments, additional heat sinks may be provided within the bottom of the lower part of the plurality of battery cells, while no heat sink may be provided within the bottom of the lower part of the longitudinal beam.

[0023] In some embodiments, the first cell lead includes a first portion relatively close to the cover and a second portion relatively further away from the cover, wherein in the first direction, the maximum dimension of the second portion is even greater than the maximum dimension of the first portion, and the second portion may be composed of a plane perpendicular to the third direction. The wiring structure may include a wiring board extending along the upper surface of the longitudinal beam and the busbar coupled on the wiring board.

[0024] 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 an adjacent battery cell, and an additional heat sink extending in the first direction may be further provided within the mesa portion.

Advantages of the Invention

[0025] The battery pack of the present invention has the effect of controlling the internal temperature rise by quickly removing the heat generated inside, thereby improving safety.

Brief Description of the Drawings

[0026] [Figure 1] It is a separated perspective view showing the main part of a battery pack according to an embodiment of the present invention. [Figure 2] It is a perspective view showing the main part of the lower case of a pack case according to an embodiment of the present invention. [Figure 3] It is a side sectional view showing the main part of a cross section obtained by cutting open the battery pack of FIG. 1 along the line III-III'. [Figure 4] It is a perspective view showing the main part of a battery cell according to an embodiment of the present invention. [Figure 5] It is a partial enlarged view showing a part of the battery cell centered on the cell lead portion of the battery cell according to an embodiment of the present invention. [Figure 6] It is a partial enlarged view of a part of the battery cell centered on the cell lead portion of the battery cell as viewed from the x direction. [Figure 7] It is a partial enlarged view of a part of the battery cell centered on the cell lead portion of the battery cell as viewed from the y direction. [Figure 8] It is a partial enlarged view of a part of the battery cell centered on the cell lead portion of the battery cell as viewed from the z direction. [Figure 9] It is a perspective view showing a pair of adjacent battery cells electrically connected by a bus bar. [Figure 10]Figure 9 shows the second part and a cross-sectional view of the busbar cut along the line X-X'. [Figure 11] This is a side cross-sectional view showing a key part of the cross-section of a battery pack according to another embodiment of the present invention. [Figure 12] This is a flowchart showing a method for manufacturing a battery pack according to one embodiment of the present invention. [Figure 13a] This is a perspective view showing a method for manufacturing a battery pack according to one embodiment of the present invention. [Figure 13b] This is a perspective view showing a method for manufacturing a battery pack according to one embodiment of the present invention. [Modes for carrying out the invention]

[0027] Preferred embodiments of the concept of the present invention will be described in detail below with reference to the accompanying drawings. However, embodiments of the concept of the present invention may be modified into various different forms, and the scope of the concept of the present invention should not be construed as being limited by the embodiments described above. It is preferable that embodiments of the concept of the present invention be construed as being provided to more fully explain the concept of the present invention to a person of average knowledge in the art. The same reference numerals mean the same element throughout. Furthermore, the various elements and areas in the drawings are depicted schematically. Therefore, the concept of the present invention is not limited by the relative sizes or spacings depicted in the accompanying drawings.

[0028] Terms such as "first," "second," etc., may be used to describe a variety of components, but the components are not limited by these terms. The terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the concept of the present invention, the first component may be named the second component, and conversely, the second component may be named the first component.

[0029] The terms used in this application are used solely to describe specific embodiments and are not intended to limit the concepts of the invention. A singular expression includes plural expressions unless the context clearly indicates otherwise. In this application, expressions such as “includes” or “having” are intended to specify the presence of features, quantities, steps, operations, components, parts, or combinations thereof described in the specification, and are understood not to preemptively exclude the presence or possibility of adding one or more other features, quantities, steps, operations, components, parts, or combinations thereof.

[0030] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as those commonly understood by those of ordinary skill in the art to which the concepts of this invention pertain. Furthermore, terms defined in commonly used dictionaries may be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and should not be interpreted in an overly formal sense unless explicitly defined herein.

[0031] Where a particular embodiment can be otherwise realized, a specific sequence of steps may be performed in a different order than that described. For example, two steps described consecutively may be performed substantially simultaneously, or in the reverse order of the description.

[0032] In the accompanying drawings, deformation of the illustrated shapes may be expected, for example, due to manufacturing techniques and / or tolerances. Therefore, embodiments of the present invention should not be construed as being limited to specific shapes of the regions illustrated herein, and may include, for example, changes in shape resulting from the manufacturing process. All terms used herein, "and / or," include each of the components mentioned and all combinations of one or more of them. The term "substrate" as used herein may mean the substrate itself or a laminated structure including a substrate and a predetermined layer or film formed on its surface. The term "surface of the substrate" as used herein may mean the exposed surface of the substrate itself or an outer surface such as a predetermined layer or film formed on the substrate.

[0033] Figure 1 is a separated perspective view showing the main parts of a battery pack 10 according to one embodiment of the present invention. In Figure 1, the battery pack 10 is shown as being defined in a vertical coordinate system defined as a first direction along the x-axis, a second direction along the y-axis, and a third direction along the z-axis, all of which are perpendicular to each other. However, the first, second, and third directions only need to be perpendicular to each other and are not particularly limited.

[0034] Referring to Figure 1, the battery pack 10 includes a plurality of battery cells 100 stacked in a first direction (for example, the x-axis direction) and a pack case 300 that houses the plurality of battery cells 100.

[0035] The pack case 300 has an internal space 330 capable of housing 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.

[0036] Although not explicitly shown in Figure 1, the pack case 300 may be provided with wires that electrically connect the plurality of battery cells 100 to an external electrical load.

[0037] In some embodiments, the lower case 320 may take the form of a box with an open top, and a number of battery cells 100 can be housed in the internal space 330. The upper case 310 may be configured as a lid that covers the open top of the lower case 320. In some embodiments, the upper case 310 may be configured as a box with an open bottom.

[0038] The pack case 300 described above may include plastic or metal materials. In addition, the pack case 300 may employ a variety of exterior material materials for battery packs known at the time of filing of the present invention.

[0039] The battery pack 10 described above may further include a battery management system. The battery management system (BMS) may be installed in the internal space of the pack case 300 and configured to comprehensively control the charging and discharging operations and data transmission / reception operations of the battery cells 100. The battery management system may be provided on a pack-by-pack basis rather than on a module-by-module basis. More specifically, the battery management system may be configured to control the charging and discharging state, power state, and performance state of the battery cells 100 via the pack voltage and pack current.

[0040] The battery pack 10 may further include a battery disconnect unit. The battery disconnect unit (BDU) may be configured to control the electrical coupling of battery cells in order to manage the power capacity and function of the battery pack 10. For this purpose, the battery disconnect unit may include a power relay, a current sensor, a fuse, and the like. The battery disconnect unit may also be provided on a pack-by-pack basis rather than on a module basis, and a variety of disconnect units known at the time of filing of the present invention may be employed.

[0041] In addition, the battery pack 10 may further include various battery pack components known at the time of filing of the present invention. For example, the battery pack 10 according to one embodiment of the present invention may further include an MSD (manual service disconnector) that allows an operator to manually disconnect the service plug and shut off the power supply.

[0042] Figure 2 is a perspective view showing the main part of the lower case 320 of the pack case 300 according to one embodiment of the present invention.

[0043] Referring to Figure 2, the lower case 320 includes a pair of first outer walls 321 extending in the first direction (e.g., the x-axis direction). The lower case 320 also includes a pair of second outer walls 322 extending in the second direction (e.g., the y-axis direction) and, together with the pair of first outer walls 321, define the internal space 330 of the pack case 300. In some embodiments, the first outer walls 321 and the second outer walls 322 may be integral.

[0044] The lower case 320 further includes a longitudinal beam 323 extending parallel to the first outer walls 321 between the pair of first outer walls 321. The longitudinal beam 323 extends in the first direction (e.g., the x-axis direction) and may be in contact with the pair of second outer walls 322. In some embodiments, the longitudinal beam 323 may be integral with the second outer walls 322.

[0045] In some embodiments, the longitudinal beam 323 may have a mesa structure. In some embodiments, the upper surface of the longitudinal beam 323 may be lower than the upper surface of the second outer wall 322. In some embodiments, the side walls of the longitudinal beam 323 may extend diagonally downward with respect to its upper surface. In other embodiments, the side walls of the longitudinal beam 323 may extend perpendicularly with respect to its upper surface. In some embodiments, the side walls of the longitudinal beam 323 may be configured to correspond to the edge shape of an adjacent battery cell 100.

[0046] The vertical beam 323, together with adjacent first outer walls 321, can define an internal space 330 in which a battery cell 100 (see Figure 1) can be accommodated.

[0047] 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, two adjacent longitudinal beams 323 may define an internal space 330 in which a battery cell 100 (see Figure 1) can be accommodated.

[0048] Figure 3 is a side cross-sectional view showing the main part of the cross-section obtained by cutting the battery pack 10 in Figure 1 along the line III-III'.

[0049] Referring to Figures 2 and 3, each of the pair of first outer walls 321 may include an outer wall body 3211 extending in the first direction (for example, the x-axis direction) and a mesa portion 3212 projecting from the outer wall body 3211 toward a battery cell 100 adjacent to the outer wall body 3211.

[0050] The mesa portion 3212 extends in the first direction (for example, the x-axis direction) and may be in contact with the pair of second outer walls 322. In some embodiments, the mesa portion 3212 may be integral with the outer wall body 3211 and / or the second outer wall 322.

[0051] The upper surface of the mesa portion 3212 may be lower than the upper surface of the second outer wall 322. In some embodiments, the upper surface of the mesa portion 3212 may be coplanar with the upper 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.

[0052] In some embodiments, the sidewalls of the mesa portion 3212 may extend diagonally downward with respect to its upper surface. In other embodiments, the sidewalls of the mesa portion 3212 may extend perpendicularly with respect to its upper surface. In some embodiments, the sidewalls of the mesa portion 3212 may be configured to correspond to the edge shape of the adjacent battery cell 100.

[0053] 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 to each other. In some embodiments, the wiring structure 350 may include a wiring board 352 extending along the longitudinal beam 323 in the first direction (e.g., the x-axis direction). The wiring board 352 may include an insulating layer and any conductive lines formed on the insulating layer.

[0054] In some embodiments, the wiring structure 350 may further include busbars 200 on the wiring board 352.

[0055] The busbar 200 described above can be any conductor that electrically connects two battery cells 100 adjacent to each other in the first direction (for example, the x-axis direction). This will be explained in more detail later.

[0056] Within the longitudinal beam 323, a heat sink 3251 may be provided that penetrates the longitudinal beam 323 in the first direction (e.g., the x-axis direction). The heat sink 3251 may be, for example, a passage for a cooling fluid extending in the first direction (e.g., the x-axis direction). The cooling fluid may be a liquid, a gas, or a mixture thereof. For example, the cooling fluid may be, but is not limited to, water, air, alcohol, nitrogen, etc.

[0057] As shown in Figure 3, the cell leads 110 of the battery cell 100 are coupled to the busbar 200 at the top of the vertical beam 323, and a large amount of heat is generated where the cell leads 110 and the busbar 200 are coupled during the operation of the battery pack 10. Therefore, the heat sink 3251 that penetrates the inside of the vertical beam 323 can quickly remove the large amount of heat generated, thereby controlling the temperature rise of the battery pack 10 and improving the safety of the battery pack 10.

[0058] The heat sink 3251 may be connected to a cooling fluid reservoir provided outside the pack case 300 to communicate with it fluidly. In some embodiments, the cooling fluid reservoir may be configured to cool the fluid stored inside it.

[0059] In some embodiments, a wiring structure 350 may also be provided on the upper surface of the mesa portion 3212 of the first outer wall 321. The wiring structure 350 on the mesa portion 3212 may also include a wiring board 352 and busbars 200.

[0060] Within the mesa portion 3212, a heat sink 3252 may be provided that penetrates the mesa portion 3212 in the first direction (e.g., the x-axis direction). The heat sink 3252 may be, for example, a passage for a cooling fluid extending in the first direction (e.g., the x-axis direction). The cooling fluid may be a liquid, a gas, or a mixture thereof. For example, the cooling fluid may be, but is not limited to, water, air, alcohol, nitrogen, etc.

[0061] In some embodiments, the cell leads 110 of the battery cell 100 are coupled to the busbar 200 at the top of the mesa portion 3212, and a large amount of heat is generated where the cell leads 110 and the busbar 200 are coupled during the operation of the battery pack 10. Therefore, the heat sink 3252 that penetrates the inside of the mesa portion 3212 can quickly remove the large amount of heat generated, thereby controlling the temperature rise of the battery pack 10 and improving the safety of the battery pack 10.

[0062] The heat sink 3252 may be connected to a cooling fluid reservoir provided outside the pack case 300 to communicate with it. In some embodiments, the cooling fluid reservoir may be configured to cool the fluid stored inside it.

[0063] The lower case 320 further includes a bottom 326. The bottom 326 is provided below the pair of first outer walls 321, the pair of second outer walls 322, and the longitudinal beam 323. In some embodiments, the bottom 326 may be integrally formed with one or more of the pair of first outer walls 321, the pair of second outer walls 322, and the longitudinal beam 323.

[0064] In some embodiments, an additional heat sink 3253 may be provided within the bottom portion 326 of the battery cell 100. The additional heat sink 3253 may be, for example, a passage for a cooling fluid extending in the first direction (e.g., the x-axis direction). The cooling fluid may be a liquid, a gas, or a mixture thereof. For example, the cooling fluid may be, but is not limited to, water, air, alcohol, nitrogen, etc.

[0065] The additional heatsink 3253 can quickly remove the heat generated during the 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.

[0066] In some embodiments, a heat sink may not be provided in the bottom 326 of the lower part of the vertical beam 323. In some embodiments, a heat sink may not be provided in the bottom 326 of the lower part of the mesa portion 3212.

[0067] Figure 4 is a perspective view showing the main parts of a battery cell 100 according to one embodiment of the present invention.

[0068] Referring to Figure 4, the battery cell 100 includes an electrode assembly 101, a cover 105 surrounding the electrode assembly 101, and cell leads 110 protruding from one side of the cover 105 in the second direction (for example, the y-direction).

[0069] 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.

[0070] In some embodiments, the battery cell 100 has a thin plate-like body and may preferably consist of a pouch cell structure. The pouch cell may consist of an electrode assembly 101 formed by alternately stacking a positive electrode, a separator, and a negative electrode, with an electrode tab drawn out from at least one side and connected to the cell lead 110. The positive and negative electrodes may be manufactured by coating at least one surface of a current collector with a slurry of electrode active material, binder resin, conductive material, and other additives. As the electrode active material, in the case of the positive electrode, a conventional positive electrode active material such as a lithium-containing transition metal oxide may be used, and in the case of the negative electrode, a conventional negative electrode active material such as lithium metal, carbon material, and metal compounds or mixtures thereof, in which lithium ions can be intercalated and released, may be used. Furthermore, as the separator, a conventional porous polymer film used in lithium secondary batteries may be used.

[0071] A standard lithium secondary battery electrolyte can be used as the electrolyte housed in the cover 105 together with the electrode assembly 101. The cover 105 is made of a sheet material and has a storage compartment for housing the electrode assembly 101. Preferably, the cover 105 is formed by joining a first case and a second case, both formed by processing the sheet material into a predetermined shape. The sheet material forming the cover 105 has a multilayer structure in which an outermost resin layer made of an insulating material such as polyethylene terephthalate (PET) or nylon, a metal layer made of aluminum that maintains mechanical strength and prevents the penetration of moisture and oxygen, and an inner resin layer made of a polyolefin-based material that has heat adhesion and acts as a sealing material are laminated together.

[0072] The sheet material forming the cover 105 may have a predetermined adhesive resin layer interposed between the internal resin layer and the metal layer, and between the external resin layer and the metal layer, as needed. The adhesive resin layer is for smooth adhesion between dissimilar materials and is formed in single or multilayer form. The material is usually a polyolefin resin, or a polyurethane resin may be used for smooth processing, and mixtures thereof can also be used.

[0073] The battery cell 100 described above has two main surfaces S1 and S2 perpendicular to the first direction (for example, the x-direction), as shown in Figure 4. 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 in Figure 4 and are parallel to each other.

[0074] Figure 5 is a partially enlarged view showing a portion of the battery cell 100, centering on the cell lead 110 portion of the battery cell 100 according to one embodiment of the present invention.

[0075] Referring to Figure 5, the cell lead 110 protrudes from one side of the cover 105 in the second direction (for example, the y-axis direction) and includes a first portion 111 and a second portion 112. The first portion 111 may be located relatively closer to the cover 105 than the second portion 112. The second portion 112 may be the leading edge of the cell lead 110 in the second direction.

[0076] The first portion 111 and the second portion 112 can be electrically connected to each other. In some embodiments, the first portion 111 and the second portion 112 can be in direct contact with each other, but the present invention is not limited thereto. In some embodiments, the first portion 111 and the second portion 112 can be integrated.

[0077] In some embodiments, the first portion 111 may have the form of a flat plate with a plane that is generally perpendicular to the first direction (e.g., the x-axis direction) as its main plane. In some embodiments, the second portion 112 may be composed of a plane perpendicular to the third direction (e.g., the z-axis direction). Here, the fact that the second portion 112 is composed of a plane perpendicular to the third direction means that the upper and lower surfaces of the second portion 112 are perpendicular to the third direction but do not contain through holes within 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 but do not contain through holes within 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 but may contain through holes within the upper and lower surfaces.

[0078] Figure 6 is a magnified view of a portion of the battery cell 100, centered on the cell lead 110 portion, as seen from the x-direction.

[0079] Referring to Figure 6, the first portion 111 of the cell lead 110 has a first upper surface 111a and a first lower surface 111b. The second portion 112 of the cell lead 110 has a second upper surface 112a and a second lower surface 112b. Here, "upper surface" and "lower surface" are relative concepts, and the part located relatively above can be defined as the "upper surface" and the part located relatively below as the "lower surface," or one of the two can be defined as the "upper surface" and the other as the "lower surface."

[0080] A center line CL may be defined for the first portion 111 described above. The center line CL is a straight line in a second direction (e.g., the y-axis direction) that bisects the first portion 111 in a third direction (e.g., the z-axis direction).

[0081] In the third direction described above, the center line CL may be located between the second upper surface 112a and the second lower surface 112b of the second portion 112.

[0082] In the third direction described above, the first portion 111 has a first dimension H1, and the second portion 112 has a second dimension H2 which 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 may have a range of about 0.5% to about 50%, about 1% to about 48%, about 1.5% to about 45%, about 2% 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%, about 8.5% to about 10%, or any two of these values.

[0083] If the second dimension H2 is too small compared to the first dimension H1, the mechanical strength of the second part 112 will be insufficient and it 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 increase unnecessarily.

[0084] Figure 7 is a magnified view of a portion of the battery cell 100, centered on the cell lead 110 portion, as seen from the y-direction.

[0085] Referring to Figure 7, in the first direction (for example, the x-axis direction), the first portion 111 of the cell lead 110 has a first maximum dimension d1, and the second portion 112 of the cell lead 110 has a second maximum dimension d2. The second maximum dimension d2 is even larger than the first maximum dimension d1. For example, the second maximum dimension d2 may be about 2 to 20 times the first maximum dimension d1. In some embodiments, the second maximum dimension d2 may be approximately 2 to 20 times, 2.5 to 19.5 times, 3 to 19 times, 3.5 to 18.5 times, 4 to 18 times, 4.5 to 17.5 times, 5 to 17 times, 5.5 to 16.5 times, 6 to 16 times, 6.5 to 15.5 times, 7 to 15 times, 7.5 to 14.5 times, 8 to 14 times, 8.5 to 13.5 times, 9 to 13 times, 9.5 to 12.5 times, 10 to 12 times, 10.5 to 11.5 times, or a range between any two of these values.

[0086] If the second maximum dimension d2 is too small compared to the first maximum dimension d1, welding the bus bar and the second part 112, as described later, may not be easy. 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 (e.g., the x-axis direction) may increase excessively, and the energy density may decrease.

[0087] In some embodiments, the second maximum dimension d2 of the second portion 112 in a first direction (e.g., the x-axis direction) may be greater than the cell thickness d3 defined between the first main surface S1 and the second main surface S2 of the battery cell 100. In other embodiments, the second maximum dimension d2 of the second portion 112 in a first direction (e.g., the x-axis direction) may be less than the cell thickness d3 defined between the first main surface S1 and the second main surface S2 of the battery cell 100.

[0088] Figure 8 is a magnified view of a portion of the battery cell 100, centered on the cell lead 110 portion, as seen from the z direction.

[0089] Referring to Figure 8, the projection of the second portion 112 onto a plane perpendicular to the third direction (e.g., the z-axis direction) (e.g., the xy-plane) may have a circular shape. In some embodiments, the projection of the second portion 112 onto the xy-plane may have shapes other than a circle, such as an ellipse, polygon (e.g., quadrilateral, pentagon, hexagon, etc.), or any other arbitrary shape. However, having a circular shape may be advantageous in terms of the versatility of welding methods that can be used for subsequent welding with busbars, structural stability, and ease of handling.

[0090] In some embodiments, when the projection is circular, the second portion 112 may have the form of a cylinder or a frustocone. When the projection is polygonal, the second portion 112 may have the form of a polygonal prism or a frustocone.

[0091] The area of ​​the projection of the second part 112 may be about 2 to 20 times the area of ​​the projection of the first part 111. In some embodiments, the area of ​​the projection of the second part 112 may be about 2 to 20 times, about 2.5 to 19 times, about 3 to 18 times, about 3.5 to 17 times, about 4 to 16 times, about 4.5 to 15 times, about 5 to 14 times, about 5.5 to 13 times, about 6 to 12 times, about 6.5 to 11 times, about 7 to 10 times, about 7.5 to 9 times, or in a range between any two of these numbers.

[0092] If the projection area of ​​the second part 112 is too small compared to the projection area of ​​the first part 111, welding the busbar and the second part 112, as described later, may not be easy. If the projection area of ​​the second part 112 is too large compared to the projection area of ​​the first part 111, the weight of the battery cell 100 may increase unnecessarily.

[0093] Since the second portion 112 of the cell lead 110 of the battery cell 100 has a planar shape perpendicular to the third direction (for example, the z-axis direction), it is possible to electrically interconnect the battery cell 100 after it has been coupled to the pack case 300. Therefore, the battery pack according to the embodiment of the present invention has a simple number of parts, can be manufactured inexpensively, has excellent productivity, and has little concern about product failure.

[0094] Figure 9 is a perspective view showing a pair of adjacent battery cells 100_1 and 100_2 electrically connected by a busbar 200.

[0095] Referring to Figure 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.

[0096] 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 can be electrically connected by a busbar 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 can be electrically connected by a busbar 200.

[0097] 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 busbar 200, may have the same polarity or may have different polarities.

[0098] The busbar 200 may be positioned to extend in a first direction (e.g., the x-axis direction) and may be configured to contact the lower surfaces of the second portion 112_1 of the first battery cell 100_1 and the second portion 112_2 of the second battery cell 100_2, respectively. In some embodiments, the busbar 200 may have the form of a strip extending in the first direction. In this case, the flat surface of the busbar 200 may face the second portion 112_1 of the first battery cell 100_1 and the second portion 112_2 of the second battery cell 100_2 in a third direction (e.g., the z-axis direction).

[0099] The busbar 200 may be provided on a wiring board 352 located on the upper part of the longitudinal beam 323, as described with reference to Figures 2 and 3. In some embodiments, the busbar 200 may be provided on a wiring board 352 located on the upper part of the mesa 3212, as described with reference to Figures 2 and 3.

[0100] 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 vertical 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 may be electrically connected to the busbar 200 at the top of the vertical beam 323.

[0101] Figure 10 is a cross-sectional view showing the second part 112_1, 112_2 and busbar 200 of Figure 9, incised along the line X-X'.

[0102] Referring to Figure 10, the busbar 200 may have a recess R in the third direction (e.g., the z-axis direction) in the portion that overlaps with the second portions 112_1 and 112_2. In some embodiments, the recess R may be formed as a result of welding the busbar 200 and the second portions 112_1 and 112_2 in the third direction. However, since the recess R is a result of partial melting and solidification of the contact area between the busbar 200 and the second portions 112_1 and 112_2 due to welding, it may appear as a trace of melting and solidification in some cases.

[0103] In Figure 10, the recess R is shown to be formed continuously with the flat surface of the busbar 200, but in some cases, a slight bulge may be formed around the recess R.

[0104] In some embodiments, the welding method may prevent the recess R from being clearly identified as an interface.

[0105] Figure 11 is a side cross-sectional view showing the main part of the cross-section of a battery pack 10 according to another embodiment of the present invention.

[0106] Referring to Figure 11, in some embodiments, an additional heat sink may be provided within the bottom 326 of the lower part of the vertical beam 323. In some embodiments, an additional heat sink may also be provided within the bottom 326 of the lower part of the mesa portion 3212. By providing these additional heat sinks, the heat generated at the point where the cell lead and the busbar 200 are coupled can be removed more quickly.

[0107] Figure 12 is a flowchart showing a method for manufacturing a battery pack 10 according to one embodiment of the present invention. Figures 13a and 13b are perspective views showing a method for manufacturing a battery pack 10 according to one embodiment of the present invention.

[0108] Referring to Figures 12 and 13a, multiple battery cells 100 can be directly placed inside the pack case 300 (S10). Here, directly placing the multiple battery cells 100 inside the pack case 300 means placing the multiple battery cells 100 inside the pack case 300 without configuring them as modules.

[0109] In some embodiments, the plurality of battery cells 100 may be placed individually within the pack case 300. In other embodiments, the plurality of battery cells 100 may be stacked in groups of two or more before being placed within the pack case 300.

[0110] The method of arranging the battery cells 100 inside the pack case 300 is not particularly limited, and they can be arranged inside the pack case 300 by any known method. The configuration of the pack case 300 has been explained with reference to Figures 2 and 3, so a detailed explanation is omitted here. Also, the specific configuration of each battery cell 100 has been explained with reference to Figures 4 to 10, so a detailed explanation is omitted here.

[0111] Referring to Figures 12 and 13b, cell leads 110_1 and 110_2 protruding in a second direction (e.g., the y-axis direction) of two adjacent battery cells 100 can be electrically connected to the busbar 200 (S20). The cell leads 110_1 and 110_2 can be connected to the busbar 200 by welding in a third direction (e.g., the z-axis direction).

[0112] In some embodiments, the busbar 200 may be positioned within the pack case 300 before the plurality of battery cells 100 are placed within the pack case 300. In some embodiments, the busbar 200 may be positioned on the cell leads 110_1, 110_2 after the plurality of battery cells 100 have been placed within the pack case 300. The busbar 200 can then be welded to the cell leads 110_1, 110_2. Any known welding method may be used and is not particularly limited.

[0113] Since the second portion 112 of the cell lead 110 of the battery cell 100 has a planar shape perpendicular to the third direction (for example, the z-axis direction), it is possible to electrically interconnect the battery cell 100 after it has been coupled to the pack case 300. Therefore, the battery pack according to the embodiment of the present invention has a simple number of parts, can be manufactured inexpensively, has excellent productivity, and has little concern about product failure.

[0114] As described above, embodiments of the present invention have been described in detail, but a person with ordinary skill in the art to which the present invention pertains can modify and implement the present invention in various ways without departing from the spirit and scope of the invention as defined in the appended claims. Accordingly, future modifications of embodiments of the present invention will not depart from the art of the present invention. [Explanation of Symbols]

[0115] 10 Battery Packs 100 battery cells 100_1 First battery cell 100_2 Second battery cell 101 Electrode assembly 105 Cover 110 Cell Lead 110_1 Cell Lead 110_2 Cell Lead 111 Part 1 111_1 Part 1 111_2 Part 1 111a 1st top surface 111b 1st bottom surface 112 Part 2 112_1 2nd part 112_2 2nd part 112a 2nd top surface 112b 2nd bottom surface 200 bus bar 300 pack case 310 Top Case 320 Lower Case 321 1st outer wall 322 Second outer wall 323 Vertical beam 326 Bottom 330 Interior space 350 Wiring structure 352 Wiring board 3211 Exterior wall main body 3212 Mesa 3251 Heatsink 3252 Heatsink 3253 Heatsink CL center line d1 First maximum dimension d2 Second maximum dimension H1 First dimension H2 Second dimension R recess S1 1st main surface S2 2nd main surface

Claims

1. In a vertical coordinate system defined as a first direction, a second direction, and a third direction that are perpendicular to each other, A plurality of battery cells stacked in the first direction, The device includes a pack case that houses the battery cells in its internal space, The aforementioned pack case is A pair of first outer walls extending in the first direction, A pair of second outer walls extending in the second direction and defining the internal space of the pack case together with the pair of first outer walls, A longitudinal beam extending parallel to the first outer wall between the pair of first outer walls, The first outer wall, the second outer wall, and the bottom portion provided at the lower part of the longitudinal beam, The upper part of the vertical beam is provided with a wiring structure that is electrically connected to the plurality of battery cells. A battery pack is provided inside the aforementioned vertical beam, with a heat sink.

2. The battery pack according to claim 1, wherein the heat sink includes a passage for a cooling fluid extending in the first direction.

3. The battery pack according to claim 1 or 2, further comprising additional heat sinks in the bottom portion of the lower part of the plurality of battery cells.

4. The battery pack according to claim 3, wherein a heat sink is not provided in the bottom of the lower part of the vertical beam.

5. The battery pack according to claim 1 or 2, wherein 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 in the second direction to the top of the longitudinal beam.

6. The first cell lead includes a first portion that is relatively close to the cover and a second portion that is relatively further away from the cover. The battery pack according to claim 5, wherein in the first direction, the maximum dimension of the second portion is even larger than the maximum dimension of the first portion, and the second portion is composed of a plane perpendicular to the third direction.

7. The aforementioned wiring structure is A wiring board extending along the upper surface of the vertical beam, The circuit board includes a busbar coupled to the circuit board, The battery pack according to claim 6, wherein the second portion is joined to the busbar by welding in the third direction.

8. Each of the pair of first outer walls is The exterior wall body extending in the first direction, It includes a mesa portion that protrudes from the outer wall body toward an adjacent battery cell, The battery pack according to claim 1 or 2, further comprising an additional heat sink extending in the first direction within the mesa portion.

9. The battery pack according to claim 8, wherein the upper surface of the mesa portion is lower than the upper surface of the outer wall body and is at the same height as the upper surface of the vertical beam.

10. The battery pack according to claim 8, further comprising an additional wiring structure on the upper surface of the mesa portion.

11. The battery pack according to claim 8, wherein no heat sink is provided in the bottom of the lower part of the mesa portion.

12. In a vertical coordinate system defined as a first direction, a second direction, and a third direction that are perpendicular to each other, The steps include: placing multiple battery cells directly inside the pack case, The step includes electrically connecting the cell leads of at least two adjacent battery cells among the plurality of battery cells that protrude in the second direction using a busbar, The step of electrically connecting the cell leads using a busbar includes the step of welding each of the cell leads to the busbar in the third direction, The aforementioned pack case is A pair of first outer walls extending in the first direction, A pair of second outer walls extending in the second direction and defining the internal space of the pack case together with the pair of first outer walls, A longitudinal beam extending parallel to the first outer wall between the pair of first outer walls, The first outer wall, the second outer wall, and the bottom portion provided at the lower part of the longitudinal beam, The upper part of the vertical beam is provided with a wiring structure that is electrically connected to the plurality of battery cells. A method for manufacturing a battery pack, wherein a heat sink is provided inside the longitudinal beam.

13. A method for manufacturing a battery pack according to claim 12, wherein additional heat sinks are further provided in the bottom of the lower part of the plurality of battery cells, and no heat sinks are provided in the bottom of the lower part of the longitudinal beam.

14. The cell lead includes a first portion that is relatively close to the cover of the battery cell and a second portion that is relatively further away from the cover. In the first direction, the maximum dimension of the second portion is even greater than the maximum dimension of the first portion, and the second portion is composed of a plane perpendicular to the third direction. The aforementioned wiring structure is A wiring board extending along the upper surface of the vertical beam, A method for manufacturing a battery pack according to claim 12 or 13, comprising: the bus bar coupled to the wiring board.

15. Each of the pair of first outer walls is The exterior wall body extending in the first direction, It includes a mesa portion that protrudes from the outer wall body toward an adjacent battery cell, A method for manufacturing a battery pack according to claim 14, further comprising an additional heat sink extending in the first direction within the mesa portion.

Images