Battery pack and method for manufacturing same

Abstract

Provided is a battery pack including: a plurality of battery cells stacked in a first direction in a vertical coordinate system defined by the first direction, a second direction, and a third direction perpendicular to each other; and a pack case configured to accommodate a plurality of battery cells in an internal space, in which each of at least one pair of adjacent battery cells among the plurality of battery cells includes an electrode assembly, a cover surrounding the electrode assembly, and a battery cell lead protruding in a second direction from one side of the cover, the battery cell lead includes a first portion relatively close to the cover and a second portion relatively away from the cover, and in the first direction, a maximum size of the second portion is larger than a maximum size of the first portion, and the second portion includes a plane perpendicular to the third direction.

Description

Technical Field

[0001] The present disclosure relates to a battery pack and a method of manufacturing the same, and more particularly, to a battery pack and a method of manufacturing the same which can be manufactured at a lower cost, have high productivity, and are less likely to malfunction due to a small number of components thereof.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0167135, filed on December 2, 2022, and Korean Patent Application No. 10-2023-0038211, filed on March 23, 2023, the entire contents of the foregoing Korean patent applications being incorporated herein by reference. Background Art

[0003] With the technological progress and growing demand for various types of mobile devices, electric vehicles, energy storage systems (ESS), etc., the attention and demand for secondary batteries as an energy source are increasing rapidly. In the past, nickel-cadmium batteries or nickel-metal hydride batteries were often used as secondary batteries. However, recently, lithium secondary batteries have been frequently used because, compared with nickel-based secondary batteries, lithium secondary batteries hardly suffer from the memory effect, and thus can be freely charged and discharged and have a very low self-discharge rate and high energy density.

[0004] Generally, in such a lithium secondary battery, a lithium-based oxide and a carbon material are used as a positive electrode active material and a negative electrode active material, respectively. The lithium secondary battery includes: an electrode assembly in which a positive electrode plate coated with a positive electrode active material and a negative electrode plate coated with a negative electrode active material are provided, and a separator is interposed between the positive electrode plate and the negative electrode plate; and a battery case for sealing and accommodating the electrode assembly together with an electrolyte.

[0005] Recently, battery packs have been widely used to drive medium and large-sized devices (e.g., electric vehicles and energy storage systems) or store energy for them. In a conventional battery pack, one or more battery modules and a control unit for controlling charging and discharging of the battery pack, e.g., a battery management system (BMS), are included in a battery pack case. Here, one or more battery modules are each configured to include a plurality of battery cells inside a module case. That is, a conventional battery pack is formed by accommodating a plurality of battery cells (secondary batteries) in a module case to form respective battery modules, and accommodating at least one such battery module in a battery pack case.

[0006] Specifically, a pouch-type battery has advantages in various aspects. For example, a pouch-type battery is lightweight and has a small dead space when pouch-type batteries are stacked. However, it is vulnerable to external impacts and has low assemblability. Therefore, generally, a battery pack is manufactured by first modularizing a plurality of battery cells and accommodating the plurality of battery cells inside a battery pack housing. As a representative example, a conventional battery pack is formed by accommodating a plurality of pouch-type battery cells in a module housing to form a battery module and accommodating at least one such battery module in a battery pack housing.

[0007] However, such a conventional battery pack may be disadvantageous in terms of energy density. Generally, when a plurality of battery cells are modularized by accommodating them in a module housing, due to various components such as the module housing or a battery stack frame, the volume of the battery pack may increase unnecessarily or the space occupied by the battery cells may decrease. In addition, the space for accommodating the battery cells may be reduced to ensure assembly tolerances for such components and the space occupied by components such as the module housing or a battery stack frame. Therefore, in the case of a conventional battery pack, there may be limitations in increasing the energy density.

[0008] In addition, a conventional battery pack may be disadvantageous in terms of assemblability. In particular, to manufacture a battery pack, a battery module is configured by modularizing a plurality of battery cells and then accommodated in a battery pack housing, so the manufacturing process of the battery pack becomes complicated. Moreover, as disclosed in the above related technical literature, the process of forming a battery cell stack using a battery stack frame, bolts, plates, etc. and the structure of the battery cell stack may be very complicated. Summary of the Invention

[0009] Technical Problem

[0010] A first technical aspect of the present disclosure aims to provide a battery pack that can be manufactured at low cost, has high productivity, and is less likely to fail due to a small number of its components.

[0011] A second technical aspect of the present disclosure aims to provide a method for manufacturing a battery pack that can be manufactured at low cost, has high productivity, and is less likely to fail due to a small number of its components.

[0012] A third technical aspect of the present disclosure aims to provide a battery cell that can be used in a battery pack that can be manufactured at low cost, has high productivity, and is less likely to fail due to a small number of its components.

[0013] Technical Solution

[0014] A first aspect of the present disclosure provides a battery pack, including: a plurality of battery cells, in a vertical coordinate system defined by a first direction, a second direction, and a third direction perpendicular to each other, the plurality of battery cells being stacked in the first direction; and a battery pack housing configured to accommodate the plurality of battery cells in an internal space, wherein each of at least a pair of adjacent battery cells among the plurality of battery cells includes an electrode assembly, a lid surrounding the electrode assembly, and a battery cell lead protruding in the second direction from one side of the lid, the battery cell lead including a first portion relatively close to the lid and a second portion relatively far from the lid, and in the first direction, the maximum dimension of the second portion is larger than the maximum dimension of the first portion, and the second portion includes a plane perpendicular to the third direction.

[0015] In some embodiments, the corresponding second portions of a pair of adjacent battery cells may be electrically connected to each other through a bus bar.

[0016] In some embodiments, the bus bar may be electrically connected to the second portion by welding in the third direction.

[0017] In some embodiments, in the third direction, the dimension of the second portion may be about 0.5% to about 50% of the dimension of the first portion.

[0018] In some embodiments, in the third direction, the center of the first portion may be located between the upper surface and the lower surface of the second portion.

[0019] In some embodiments, the upper surface of the second portion may be substantially in the same plane as the upper surface of the first portion. In some other embodiments, the lower surface of the second portion may be substantially in the same plane as the lower surface of the first portion.

[0020] In some embodiments, in the first direction, the maximum dimension of the second portion may be about 2 times to about 20 times the maximum dimension of the first portion.

[0021] In some embodiments, in a projection onto a plane perpendicular to the third direction, the projected area of the second portion may be about 2 times to about 20 times the projected area of the first portion.

[0022] A second aspect of the present disclosure provides a method for manufacturing a battery pack, the method including: in a vertical coordinate system defined by a first direction, a second direction, and a third direction perpendicular to each other, directly disposing a plurality of battery cells in a battery pack housing; and electrically connecting battery cell leads protruding in the second direction from at least two adjacent battery cells among the plurality of battery cells using a bus bar. In this case, electrically connecting the battery cell leads using a bus bar may include connecting each battery cell lead to the bus bar by welding in the third direction.

[0023] In some embodiments, the battery cell lead may include a first portion relatively close to the cover and a second portion relatively far from the cover, and in a first direction, the maximum dimension of the second portion may be larger than the maximum dimension of the first portion, and the second portion may include a plane perpendicular to a third direction.

[0024] In some embodiments, in the third direction, the dimension of the second portion may be about 0.5% to about 50% of the dimension of the first portion.

[0025] In some embodiments, the second portion may not be provided with a through hole.

[0026] In some embodiments, in the first direction, the maximum dimension of the second portion may be about 2 times to about 20 times the maximum dimension of the first portion.

[0027] A third aspect of the present disclosure provides a battery cell defined in a vertical coordinate system defined by a first direction, a second direction, and a third direction perpendicular to each other, and the battery cell includes two main surfaces perpendicular to the first direction. The battery cell includes an electrode assembly, a cover surrounding the electrode assembly, and a battery cell lead protruding from one side of the cover in the second direction. Wherein, the battery cell lead includes a first portion relatively close to the cover and a second portion relatively far from the cover. In the first direction, the maximum dimension of the second portion is larger than the maximum dimension of the first portion, and the second portion includes a plane perpendicular to the third direction, and in a projection onto a plane perpendicular to the third direction, the projected area of the second portion is about 2 times to about 20 times the projected area of the first portion.

[0028] Beneficial effects

[0029] The battery pack according to the embodiments of the present disclosure can be manufactured at low cost due to the small number of its components, has high productivity and is less prone to failure. Description of the drawings

[0030] Figure 1 is an exploded perspective view of the main body of the battery pack according to the embodiments of the present disclosure.

[0031] Figure 2 is a perspective view of the main body of the battery cell according to the embodiments of the present disclosure.

[0032] Figure 3 is a partial enlarged view of a portion of the battery cell including the battery cell lead of the battery cell according to the embodiments of the present disclosure.

[0033] Figure 4 is a partial enlarged view of a portion of the battery cell including the battery cell lead of the battery cell when viewed in the x-axis direction.

[0034] Figure 5 is a partial enlarged view of a portion of a battery cell including the battery cell lead of the battery cell when viewed in the y-axis direction.

[0035] Figure 6 is a partial enlarged view of a portion of a battery cell including the battery cell lead of the battery cell when viewed in the z-axis direction.

[0036] Figure 7a is a partial enlarged view of a portion of a battery cell including the battery cell lead of the battery cell according to another embodiment of the present disclosure.

[0037] Figure 7b is a partial enlarged view of a portion of a battery cell including the battery cell lead of the battery cell according to still another embodiment of the present disclosure.

[0038] Figure 8 is a perspective view of a pair of adjacent battery cells electrically connected to each other through a bus bar.

[0039] Figure 9 is Figure 8 a cross-sectional view of a second portion taken along line IX-IX' and the bus bar.

[0040] Figure 10 is a flowchart of a method for manufacturing a battery pack according to an embodiment of the present disclosure.

[0041] Figure 11a and Figure 11b is a perspective view showing a method for manufacturing a battery pack according to an embodiment of the present disclosure. Detailed Description of the Embodiments

[0042] Hereinafter, embodiments of the concept of the present disclosure will be described in detail with reference to the accompanying drawings. However, the embodiments of the concept of the present disclosure can be implemented in various different forms, and thus the scope of the present disclosure should not be construed as being limited by the embodiments described below. It should be understood that the embodiments of the concept of the present disclosure are provided to more completely describe the concept of the present disclosure to those of ordinary skill in the art. Throughout the specification, the same reference numerals denote the same elements. In addition, in the drawings, each element and region are schematically shown. Therefore, the concept of the present disclosure is not limited by the relative sizes of the elements shown in the drawings or the intervals between the elements.

[0043] For example, terms such as first and second can be used to describe each component, but the components are not limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present disclosure, the first component can be referred to as the second component, and similarly, the second component can be referred to as the first component.

[0044] The terms used in this application are only for describing specific embodiments and are not intended to limit the concept of the present disclosure. As used herein, unless the context clearly indicates otherwise, singular expressions are also intended to include plural forms. It should be understood that when the terms "comprising" and / or "including" are used herein, the presence of the described features, quantities, steps, operations, elements, components, or combinations thereof is specified, without excluding the presence or addition of one or more other features, quantities, steps, operations, elements, components, or combinations thereof.

[0045] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this disclosure pertains. Additionally, terms that are commonly used and defined in a dictionary should be interpreted as having a meaning consistent with the context of the relevant art, and should not be interpreted in an overly formal sense unless explicitly defined herein.

[0046] When embodiments can be implemented in different ways, certain operations can be performed in an order different from that described below. For example, two operations described consecutively can be performed substantially simultaneously or in an order opposite to that described below.

[0047] It can be expected that, for example, the shape of the components shown in the drawings can vary according to manufacturing techniques and / or tolerances. Therefore, the embodiments of the present disclosure should not be construed as being limited by the specific shapes of the respective regions shown in this specification, but should be understood to cover, for example, variations in the shapes of the respective regions caused during the manufacturing process. As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items. The term "substrate" as used herein should be understood to represent a substrate or a stacked structure including the substrate and layers, films, etc. formed on the surface of the substrate. Additionally, the expression "surface of the substrate" as used herein should be understood to represent the exposed surface of the substrate or the outer surface of a layer or film formed on the substrate.

[0048] Figure 1 is an exploded perspective view of the main body of the battery pack 10 according to an embodiment of the present disclosure. Figure 1 It is shown that the battery pack 10 is defined in a vertical coordinate system, which is defined by a first direction along the x-axis, a second direction along the y-axis, and a third direction along the z-axis that are perpendicular to each other. However, the first direction, the second direction, and the third direction are not particularly limited as long as they are perpendicular to each other.

[0049] Referring to Figure 1 , the battery pack 10 includes a plurality of battery cells 100 stacked in a first direction (e.g., the x-axis direction) and a battery pack housing 300 that houses the plurality of battery cells 100.

[0050] The battery pack housing 300 includes an internal space 330 for accommodating a plurality of battery cells 100. In some embodiments, the battery pack housing 300 may include an upper housing 310 and a lower housing 320 that define the internal space 330.

[0051] Although not explicitly shown in Figure 1 , wires may be embedded in the battery pack housing 300 to electrically connect the plurality of battery cells 100 to an external electrical load.

[0052] In some embodiments, the lower housing 320 may have a box shape with an open upper end, and a plurality of battery cells may be accommodated in the internal space 330. The upper housing 310 may be in the form of a lid to cover the open upper end of the lower housing 320. In this case, the upper housing 310 may be in the form of a box with an open lower end.

[0053] The battery pack housing 300 may include a plastic material or a metal material. Additionally, one of various external materials of battery packs known at the time of filing this disclosure may be used as the material of the battery pack housing 300.

[0054] As Figure 1 shown, the battery pack 10 may further include a battery management system (BMS) 400. The BMS 400 may be installed in the internal space 330 of the battery pack housing 300 and configured to control all operations of the battery cells 100, such as charge / discharge operations, data transmission / reception operations, etc. The BMS 400 may be provided in the unit of the battery pack rather than in the unit of the battery module. More specifically, the BMS 400 may be configured to control the charge / discharge state, power state, performance state, etc. of the battery cells 100 based on the battery pack voltage and the battery pack current.

[0055] As Figure 1 shown, the battery pack 10 may further include a battery disconnect unit (BDU) 500. The BDU 500 may be configured to control the electrical connection between the battery cells to manage the power capacity and functions of the battery pack 10. For this purpose, the BDU 500 may include: power relays, current sensors, fuses, etc. Similarly, the BDU 500 is a component provided in the unit of the battery pack rather than in the unit of the battery module, and various types of disconnect units known at the time of filing this disclosure may be used as the BDU 500.

[0056] The battery pack 10 may further include various components of battery packs known at the time of filing this disclosure. For example, according to an embodiment of the present disclosure, the battery pack 10 may further include a manual service disconnect (MSD) to cut off power by a worker manually separating a service plug.

[0057] Figure 2It is a perspective view of the main body of the battery cell 100 according to an embodiment of the present disclosure.

[0058] Referring Figure 2 , the battery cell 100 includes an electrode assembly 101, a lid 105 surrounding the electrode assembly 101, and a battery cell lead 110 protruding from one side of the lid 105 in a second direction (e.g., the y-axis direction).

[0059] In some embodiments, the battery cell 100 may be a pouch-type battery cell, but the present disclosure is not limited thereto. In some embodiments, the battery cell 100 may be a prismatic battery cell.

[0060] In some embodiments, the battery cell 100 includes a thin plate-shaped body and preferably may have the structure of a pouch-type battery cell. The pouch-type battery cell may have a structure in which a positive electrode, a separator, and a negative electrode are alternately stacked to form the electrode assembly 101, and electrode tabs are pulled out from at least one side of the electrode assembly 101 and connected to the battery cell lead 110. The positive electrode and the negative electrode can be prepared by coating at least one surface of a current collector with a slurry of, for example, an electrode active material, an adhesive resin, a conductive agent, or other additives. As the electrode active material, in the case of the positive electrode, a conventional positive electrode active material containing a lithium-containing transition metal oxide can be used, and in the case of the negative electrode, a conventional negative electrode active material that absorbs and releases lithium ions, such as lithium metal, a carbon material, a metal compound, or a mixture thereof, can be used. A conventional porous polymer film for a lithium secondary battery can be employed as the separator.

[0061] A conventional electrolyte for a lithium secondary battery can be employed as the electrolyte accommodated in the lid 105 together with the electrode assembly 101. The lid 105 is formed of a sheet material and includes a receiving portion for accommodating the electrode assembly 101. Preferably, the lid 105 is formed by combining a first housing and a second housing formed by processing the sheet material into a specific shape. The sheet material of the lid 105 has a multilayer structure in which an outermost resin layer formed of an insulating material such as polyethylene terephthalate (PET) or nylon, a metal layer formed of aluminum to maintain mechanical strength and prevent the penetration of moisture and oxygen, and an inner resin layer formed of a polyolefin-based material having thermo-bonding properties and thus serving as a sealing material are stacked.

[0062] In the sheet material of the lid 105, if necessary, an adhesive resin can be inserted between the inner resin layer and the metal layer and between the outermost resin layer and the metal layer. The adhesive resin layer is formed as a single layer or multiple layers for smooth adhesion between different types of materials, and as the material of the adhesive resin layer, a polyolefin-based resin can generally be used, a polyurethane resin can be used for smooth processing, or a mixture thereof can be used.

[0063] AsFigure 2 As shown, the battery cell 100 includes two main surfaces S1 and S2 perpendicular to the first direction (e.g., the x-axis direction). That is, the battery cell 100 may include Figure 2 a first main surface S1 and a second main surface S2 that extend along the yz plane and are parallel to each other.

[0064] Figure 3 is a partial enlarged view of a portion of the battery cell lead 110 including the battery cell 100 of the battery cell 100 according to an embodiment of the present disclosure.

[0065] Referring to Figure 3 , the battery cell lead 110 protrudes from one side of the cover 105 in the second direction (e.g., the y-axis direction) and includes a first portion 111 and a second portion 112. The first portion 111 may be closer to the cover 105 than the second portion 112. The second portion 112 may be the foremost end portion of the battery cell lead 110 in the second direction.

[0066] The first portion 111 and the second portion 112 may be electrically connected to each other. In some embodiments, the first portion 111 and the second portion 112 may be in direct contact with each other, but the present disclosure is not limited thereto. In some embodiments, the first portion 111 and the second portion 112 may be integrally formed.

[0067] In some embodiments, the first portion 111 may have a flat plate shape with a plane substantially perpendicular to the first direction (e.g., the x-axis direction) as the main surface. In some embodiments, the second portion 112 may be configured as a plane perpendicular to the third direction (e.g., the z-axis direction). Here, configuring the second portion 112 as a plane perpendicular to the third direction should be understood to mean that the upper and lower surfaces of the second portion 112 are perpendicular to the third direction and no through holes are provided. In some embodiments, the upper and lower surfaces of the second portion 112 may be perpendicular to the third direction and no through holes may be provided. In some embodiments, the upper and lower surfaces of the second portion 112 may be perpendicular to the third direction and through holes may be provided.

[0068] Figure 4 is a partial enlarged view of a portion of the battery cell 100 including the battery cell lead 110 of the battery cell when viewed in the x-axis direction.

[0069] Referring to Figure 4, the first part 111 of the battery cell lead 110 includes a first upper surface 111a and a first lower surface 111b. The second part 112 of the battery cell lead 110 includes a second upper surface 112a and a second lower surface 112b. Here, the "upper surface" and the "lower surface" are relative concepts. Therefore, the surface at a relatively high position and the surface at a relatively low position can be defined as the "upper surface" and the "lower surface" respectively, or one surface can be defined as the "upper surface", and the other surface can be defined as the "lower surface".

[0070] The center line CL can be defined based on the first part 111. The center line CL is a straight line in the second direction (e.g., the y-axis direction) that divides the first part 111 into two halves in the third direction (e.g., the z-axis direction).

[0071] In the third direction, the center line CL can be located between the second upper surface 112a and the second lower surface 112b of the second part 112.

[0072] 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. For example, the second dimension H2 can be about 0.5% to about 50% of the first dimension H1. In some embodiments, the second dimension H2 can be 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% or about 8.5% to about 10% or can be within the range between two of these values.

[0073] When the second dimension H2 is very small compared to the first dimension H1, the mechanical strength of the second part 112 may be insufficient, making it prone to damage. When the second dimension H2 is very large compared to the first dimension H1, the weight of the battery cell 100 may increase unnecessarily.

[0074] Figure 5 is a partial enlarged view of the part of the battery cell 100 including the battery cell lead 110 of the battery cell 100 when observed in the y-axis direction.

[0075] Refer to Figure 5, in a first direction (e.g., the x-axis direction), a first portion 111 of the cell lead 110 has a first maximum dimension d1, and a second portion 112 of the cell lead 110 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 can be about 2 times to about 20 times the first maximum dimension d1. In some embodiments, the second maximum dimension d2 can be 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 or about 10.5 times to about 11.5 times the first maximum dimension d1, or can be within a range between two of these values.

[0076] When the second maximum dimension d2 is very small compared to the first maximum dimension d1, it may not be easy to weld the bus bar, which will be described below, to the second portion 112. When the second maximum dimension d2 is very large compared to the first maximum dimension d1, the thickness of the cell 100 in the first direction (e.g., the x-axis direction) may increase excessively, resulting in a decrease in energy density.

[0077] In some embodiments, the second maximum dimension d2 of the second portion 112 in the first direction (e.g., the x-axis direction) can be larger than the cell thickness d3 defined between the first main surface S1 and the second main surface S2 of the cell 100. In some embodiments, the second maximum dimension d2 of the second portion 112 in the first direction (e.g., the x-axis direction) can be smaller than the cell thickness d3 defined between the first main surface S1 and the second main surface S2 of the cell 100.

[0078] Figure 6 is a partial enlarged view of the portion of the cell 100 including the cell lead 110 of the cell when viewed in the z-axis direction.

[0079] Refer to Figure 6, the projection of the second portion 112 on a plane (e.g., the xy plane) perpendicular to the third direction (e.g., the z-axis direction) can be circular. In some embodiments, the projection of the second portion 112 on the xy plane can be elliptical, polygonal (e.g., quadrilateral, pentagonal, or hexagonal), or any other shape, as well as circular. However, considering the diversity of welding methods subsequently used to weld the second portion 112 to the bus bar, structural stability, ease of operation, etc., the projection can preferably be circular.

[0080] In some embodiments, when the projection is circular, the second portion 112 can be cylindrical or conical. When the projection is polygonal, the second portion 112 can be prismatic or pyramidal.

[0081] The projected area of the second portion 112 can be about 2 times to about 20 times the projected area of the first portion 111. In some embodiments, the projected area of the second portion 112 can be about 2 times to about 20 times, about 2.5 times to about 19 times, about 3 times 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, or about 7.5 times to about 9 times the projected area of the first portion 111, or can be within the range between two of these values.

[0082] When the projected area of the second portion 112 is very small compared to the projected area of the first portion 111, it may not be easy to weld the second portion 112 to the bus bar described below. When the projected area of the second portion 112 is very large compared to the projected area of the first portion 111, the weight of the battery cell 100 may increase unnecessarily.

[0083] The second portions 112 of the battery cell leads 110 of the battery cell 100 each have a planar shape perpendicular to the third direction (e.g., the z-axis direction), so that after the battery cells 100 are combined with the battery pack housing 300, the battery cells 100 can be electrically connected to each other. Therefore, the battery pack according to an embodiment of the present disclosure can be manufactured at low cost due to the small number of its components, has high productivity, and is less likely to fail.

[0084] Figure 7a is a partial enlarged view of a portion of the battery cell lead 110 including the battery cell 100 of the battery cell 100 according to another embodiment of the present disclosure.

[0085] Referring to Figure 7a, the second part 112 can be configured such that its second upper surface 112a lies in a plane substantially the same as the first upper surface 111a of the first part 111.

[0086] Figure 7b is a partial enlarged view of a portion of a battery cell lead 110 including the battery cell 100 of the battery cell 100 according to another embodiment of the present disclosure.

[0087] Referring to Figure 7b , the second part 112 can be configured such that its second lower surface 112b is substantially in the same plane as the first lower surface 111b of the first part 111.

[0088] By configuring the second part 112 as Figure 7a or Figure 7b shown, when the second part 112 is later welded to the bus bar, an error margin can be ensured for the positioning of the bus bar.

[0089] Figure 8 is a perspective view of a pair of adjacent battery cells 100_1 and 100_2 electrically connected to each other through a bus bar 200.

[0090] Referring to Figure 8 , the battery 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 battery cell lead 110_2 of the second battery cell 100_2 includes a first part 111_2 and a second part 112_2.

[0091] The battery cell lead 110_1 of the first battery cell 100_1 and the battery cell lead 110_2 of the second battery cell 100_2 can be electrically connected to each other through the 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 can be electrically connected to each other through the bus bar 200.

[0092] The battery cell lead 110_1 of the first battery cell 100_1 and the battery cell lead 110_2 of the second battery cell 100_2 electrically connected to each other through the bus bar 200 can have the same polarity or different polarities.

[0093] The bus bar 200 can be arranged to extend in a first direction (e.g., the x-axis direction) and configured to contact the lower surfaces of the second portions 112_1 of the first battery cell 100_1 and the second portions 112_2 of the second battery cell 100_2. In some embodiments, the bus bar 200 can be in the form of a strip extending in the first direction. In this case, the flat surface of the bus bar 200 can face the second portions 112_1 of the first battery cell 100_1 and the second portions 112_2 of the second battery cell 100_2 in a third direction (e.g., the z-axis direction).

[0094] Figure 9 Is Figure 8 A cross-sectional view of the second portions 112_1 and 112_2 taken along line IX-IX’ and the bus bar 200.

[0095] Referring to Figure 9 , the portion of the bus bar 200 overlapping with the second portions 112_1 and 112_2 can have a recess R that is concave in the third direction (e.g., the z-axis direction). In some embodiments, the recess R can be produced as a result of welding the bus bar 200 to the second portions 112_1 and 112_2 in the third direction. However, the recess R is produced as a result of melting and solidifying at the interface between the bus bar 200 and the second portions 112_1 and 112_2, and thus may appear as traces of melting and solidifying in some cases.

[0096] Figure 9 Shows that the recess R is continuously formed in the flat surface of the bus bar 200, but in some cases, a slightly raised portion can be formed around the recess R.

[0097] In some embodiments, depending on the welding method, the recess R may not be recognized as a clear interface.

[0098] Figure 10 Is a flowchart of a method for manufacturing the battery pack 10 according to an embodiment of the present disclosure. Figure 11a And Figure 11b Is a perspective view showing a method for manufacturing the battery pack 10 according to an embodiment of the present disclosure.

[0099] Referring to Figure 10 And Figure 11a , a plurality of battery cells 100 can be directly arranged in the battery pack housing 300 (S10). Here, arranging a plurality of battery cells 100 directly in the battery pack housing 300 should be understood as arranging a plurality of battery cells 100 in the battery pack housing 300 without modularizing the plurality of battery cells 100.

[0100] In some embodiments, a plurality of battery cells 100 may be individually disposed one by one in the battery pack housing 300. In some other embodiments, two or more of the plurality of battery cells 100 may be stacked and then disposed in the battery pack housing 300.

[0101] The method of disposing the battery cell 100 in the battery pack housing 300 is not particularly limited, and the battery cell 100 may be disposed in the battery pack housing 300 by any known method. The configurations of the respective battery cells 100 have been described in detail above with reference to Figures 1 to 7b and thus a detailed description thereof is omitted herein.

[0102] With reference to Figure 10 and Figure 11b , the battery cell leads 110_1 and 110_2 protruding from two adjacent battery cells 100 in the second direction (e.g., the y-axis direction) may be electrically connected to the bus bar 200 (S20). The battery cell leads 110_1 and 110_2 may be connected to the bus bar 200 by welding in the third direction (e.g., the z-axis direction).

[0103] In some embodiments, the bus bar 200 may be disposed in the battery pack housing 300 before the plurality of battery cells 100 are disposed in the battery pack housing 300. In some embodiments, after the plurality of battery cells 100 are disposed in the battery pack housing 300, the bus bar 200 may be disposed on the battery cell leads 110_1 and 110_2. Thereafter, the bus bar 200 may be welded to the battery cell leads 110_1 and 110_2. The welding method may be any known method and is not particularly limited.

[0104] The second portions 112_1 and 112_2 of the battery cell leads 110_1 and 110_2 of the battery cell 100 each have a planar shape perpendicular to the third direction (e.g., the z-axis direction), and thus, after the battery cells 100 are combined with the battery pack housing 300, the battery cells 100 may be electrically connected to each other. Therefore, the battery pack according to an embodiment of the present disclosure can be manufactured at low cost due to the small number of its components, has high productivity, and is less likely to malfunction.

[0105] Although the embodiments of the present disclosure have been described in detail above, those of ordinary skill in the art in the field of the present disclosure can implement the present disclosure in many different forms without departing from the spirit and scope of the present disclosure defined in the appended claims. Therefore, it should be understood that all modifications in the embodiments of the present disclosure fall within the scope of the present disclosure.

Claims

1. A battery pack, comprising: A plurality of battery cells, in a vertical coordinate system defined by a first direction, a second direction, and a third direction perpendicular to each other, the plurality of battery cells being stacked in the first direction; And A battery pack housing configured to accommodate the plurality of battery cells in an internal space, Wherein, each of at least a pair of adjacent battery cells among the plurality of battery cells includes an electrode assembly, a cover surrounding the electrode assembly, and a battery cell lead protruding in the second direction from one side of the cover, The battery cell lead includes a first portion relatively close to the cover and a second portion relatively far from the cover, and The maximum dimension of the second portion in the first direction is larger than the maximum dimension of the first portion in the first direction, and the second portion includes a plane perpendicular to the third direction.

2. The battery pack according to claim 1, wherein, The corresponding second portions of the pair of adjacent battery cells are electrically connected to each other through a bus bar.

3. The battery pack according to claim 2, wherein The bus bar is electrically connected to the second portion by welding in the third direction.

4. The battery pack according to claim 2, wherein, In the third direction, the dimension of the second portion is about 0.5% to about 50% of the dimension of the first portion.

5. The battery pack according to claim 4, wherein, In the third direction, the center of the first portion is located between the upper surface and the lower surface of the second portion.

6. The battery pack according to claim 2, wherein, The upper surface of the second portion and the upper surface of the first portion are generally in the same plane.

7. The battery pack according to claim 2, wherein, The lower surface of the second portion and the lower surface of the first portion are generally in the same plane.

8. The battery pack according to claim 2, wherein, The maximum dimension of the second portion in the first direction is about 2 times to about 20 times the maximum dimension of the first portion in the first direction.

9. The battery pack according to claim 1, wherein, In the projection onto a plane perpendicular to the third direction, the projected area of the second portion is about 2 times to about 20 times the projected area of the first portion.

10. A method for manufacturing a battery pack, comprising: In a vertical coordinate system defined by a first direction, a second direction, and a third direction perpendicular to each other, directly disposing a plurality of battery cells in a battery pack housing; And Using a bus bar to electrically connect battery cell leads protruding in the second direction from at least two adjacent battery cells among the plurality of battery cells, Wherein, using the bus bar to electrically connect the battery cell leads includes connecting each battery cell lead to the bus bar by welding in the third direction.

11. The method according to claim 10, wherein, The battery cell lead includes a first portion relatively close to the cover and a second portion relatively far from the cover, and The maximum dimension of the second portion in the first direction is larger than the maximum dimension of the first portion in the first direction, and the second portion includes a plane perpendicular to the third direction.

12. The method according to claim 11, wherein, In the third direction, the dimension of the second portion is about 0.5% to about 50% of the dimension of the first portion.

13. The method according to claim 11, wherein, The second portion does not include a through hole.

14. The method according to claim 10, wherein The second portion includes a through hole.

15. A battery cell is defined in a perpendicular coordinate system defined by a first direction, a second direction, and a third direction perpendicular to each other, and the battery cell includes two main surfaces perpendicular to the first direction. The battery cell includes an electrode assembly, a cover surrounding the electrode assembly, and a battery cell lead protruding from one side of the cover in the second direction. Among them, The battery cell lead includes a first portion relatively close to the cover and a second portion relatively far from the cover. In the first direction, the maximum dimension of the second portion is larger than the maximum dimension of the first portion, and the second portion includes a plane perpendicular to the third direction, and In a projection onto a plane perpendicular to the third direction, the projected area of the second portion is about 2 to about 20 times the projected area of the first portion.

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