Battery module and battery pack including the same

Abstract

The present invention relates to a battery module and a battery pack including the battery module. According to one embodiment of the present invention, the battery module includes: a battery cell stack, which is stacked with a plurality of battery cells; a module frame, which surrounds the battery cell stack; a bus bar frame, which covers the exposed front and rear surfaces of the battery cell stack; and an end plate, which covers the bus bar frame, wherein the module frame includes a lower frame covering the bottom and both sides of the battery cell stack and an upper plate covering the top of the battery cell stack, and one or more assembly guides are arranged on the corners of the lower frame coupled to the upper plate.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2020-0052255 filed on April 29, 2020, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a battery module and a battery pack including the same, and more particularly, to a battery module with improved assemblability and a battery pack including the same. Background Art

[0004] Secondary batteries with high application characteristics and electrical characteristics (such as high energy density) are widely used in electric vehicles, hybrid vehicles, power storage devices driven by electric drive sources, and portable devices according to their products. These secondary batteries have attracted attention as new energy sources that improve environmental friendliness and energy efficiency because they do not produce any byproducts of energy use and their main advantage is that they can significantly reduce the use of fossil fuels.

[0005] In small mobile devices, each device uses one, two, or three battery cells, while medium or large devices such as cars require high power / large capacity. Therefore, medium and large battery modules are used in which a plurality of battery cells are electrically connected.

[0006] Since it is preferred to manufacture a medium or large battery module to have the smallest possible size and weight, square batteries and pouch-type batteries with high integration and small weight-to-capacity ratio are mainly used as battery cells of the medium and large battery modules. Meanwhile, in order to protect the cell stack from external impact, heat or vibration, the battery module may include a module frame that accommodates the battery cell stack in an internal space having a front opening and a rear opening.

[0007] Figure 1 is a perspective view showing a battery module according to a conventional module frame. Figure 2 is shown along Figure 1 A view of a cross section taken in the xz plane.

[0008] refer to Figure 1 and Figure 2, the battery module may include: a module frame 10, the front and rear surfaces of which are open to cover a battery cell stack 12 formed by stacking a plurality of battery cells 11; and an end plate 20, which covers the front and rear surfaces of the module frame 10. The module frame 10 may include a U-shaped frame 10a and an upper plate 10b covering an open portion of the U-shaped frame 10a. The U-shaped frame 10a may include: a bottom 10a1, which covers the lower surface of the battery cell stack 12; and two side portions 10a2, which have a structure protruding upward from both sides of the bottom 10a1. The end plate 20 may include: a front plate 20a, which covers one side of the module frame 10; and a rear plate 20b, which covers the other side of the module frame 10.

[0009] In order to form such a battery module, welding may be performed to join the U-shaped frame 10a of the module frame 10 with the upper plate 10b in a state where the battery cell stack 12 is installed in the module frame 10. At this time, assembly failure may occur during the assembly process of placing the upper plate 10b on the U-shaped frame 10a. In particular, when the welding part WP is formed between the upper plate 10b and the side of the U-shaped frame 10a, a guide for assembly alignment is not provided, which may cause defects.

[0010] Therefore, a technology that can solve the problem of the prior art is needed. Summary of the invention

[0011] Technical issues

[0012] A problem to be solved by the present invention is to provide a battery module having improved assemblability and a battery pack including the battery module.

[0013] The objects to be solved by the embodiments of the present invention are not limited to the above-mentioned objects, and can be variously extended within the scope of the technical concept included in the present invention.

[0014] Technical Solution

[0015] A battery module according to an embodiment of the present invention includes: a battery cell stack in which a plurality of battery cells are stacked; a module frame that surrounds the battery cell stack; a bus bar frame that covers the front surface / rear surface of the battery cell stack exposed from the module frame; and an end plate that covers the bus bar frame, wherein the module frame includes a lower frame covering the lower portion and both sides of the battery cell stack and an upper plate covering the upper portion of the battery cell stack, and at least one assembly guide is formed at a corner of the lower frame to which the upper plate is joined.

[0016] The lower frame may include a bottom supporting a lower portion of the battery cell stack and two side portions extending upward from both ends of the bottom, and an assembly guide portion may be formed at a corner portion of an upper end of the side portion.

[0017] The fitting guide portion may include a support portion in a protrusion shape protruding in one direction and recessed portions formed on both sides of the support portion.

[0018] The recessed portion may have a relief shape in which an upper end corner of a side portion of the lower frame is recessed in a direction toward a bottom of the lower frame.

[0019] A groove portion, into which the support portion of the fitting guide portion may be fitted, is formed on the upper plate.

[0020] The groove portion may have a structure in which two corresponding corners of the upper plate are recessed in directions opposite to each other.

[0021] Avoidance portions may be formed on both ends of the groove portion.

[0022] A battery pack according to another embodiment of the present invention includes the above-mentioned battery module.

[0023] Beneficial Effects

[0024] According to the embodiment, by forming a protruding type assembly guide structure in the module frame, it is possible to prevent misalignment when assembling the module frame. Through this assembly improvement, it is possible to prevent welding defects during welding of the module frame. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a perspective view of a battery module having a conventional module frame.

[0026] Figure 2 is along Figure 1 Cross-sectional view taken along the xz plane.

[0027] Figure 3 is an exploded perspective view showing a battery module according to an embodiment of the present invention.

[0028] Figure 4 It is shown Figure 3 A perspective view of a lower frame included in a battery module.

[0029] Figure 5 is a partial perspective view showing an assembly portion of an upper plate and a lower frame in a battery module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the present invention are shown. As those skilled in the art will appreciate, the described embodiments can be modified in various different ways, all without departing from the spirit or scope of the present invention.

[0031] Parts irrelevant to the description will be omitted to clearly describe the present invention, and the same reference numerals denote the same elements throughout the specification.

[0032] In addition, in the drawings, the size and thickness of each element are arbitrarily shown for the convenience of description, and the present invention is not necessarily limited to the size and thickness shown. In the drawings, the thickness of layers, films, panels, regions, etc. are exaggerated for clarity. In the drawings, the thickness of some layers and regions is exaggerated for the convenience of description and easy understanding.

[0033] In addition, it should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element, or there can be an intermediate element. Conversely, when an element is referred to as being "directly on" another element, there are no intermediate elements. In addition, the term "on" refers to being disposed above or below a reference portion, and does not necessarily refer to being disposed on the upper side of the reference portion in the opposite direction of gravity.

[0034] In addition, unless explicitly described otherwise, terms and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

[0035] Furthermore, in the specification, the wording "in a plan view" means observing an object portion from an upper side, and the wording "in a cross-sectional view" means observing a section taken by vertically cutting the object portion from a side.

[0036] Figure 3 is an exploded perspective view showing a battery module according to an embodiment of the present invention.

[0037] refer to Figure 3 , a battery module according to an embodiment of the present invention includes: a battery cell stack 100, in which a plurality of battery cells 110 are stacked; a module frame 200, which accommodates the battery cell stack 100; a bus bar frame 400, which is formed on the front surface / rear surface of the battery cell stack 100; and an end plate 600, which covers the outside of the bus bar frame 400 based on the battery cell stack 100.

[0038] The battery cell 110 according to the present embodiment is a secondary battery and may be configured as a pouch-type secondary battery. The battery cell 110 may be configured in plurality, and the plurality of battery cells 110 may be stacked and electrically connected to each other to form a battery cell stack 100. The plurality of battery cells 110 may include an electrode assembly, a cell housing, and an electrode lead protruding from the electrode assembly, respectively.

[0039] The busbar frame 400 may be equipped with a busbar 411 and a connector 500. The connector 500 may sense voltage and temperature from a busbar or a thermistor mounted on the busbar frame 400 and transmit it to a BMS (Battery Management System). In the busbar frame 400 formed on the front surface / rear surface of the battery cell stack 100, a first connector 510 may be formed on the busbar frame 400 located at the front side of the battery cell stack 100, and a second connector 520 may be formed on the busbar frame 400 located at the rear surface of the battery cell stack 100.

[0040] Conventionally, a connector is formed on only one bus bar frame portion of two bus bar frames formed on the front surface / rear surface of the battery cell stack 100, and the bus bar frame portion on which the connector is not formed transmits voltage and temperature sensing information to a connector located on the opposite side of the reference of the battery pack through a flexible flat cable. At this time, since the flexible flat cable is placed on the upper side of the battery cell stack, a process of assembling the flexible flat cable and a process of checking whether there is any problem with the connection made by the flexible flat cable are separately required.

[0041] According to an embodiment of the present invention, a first connector 510 and a second connector 520 are respectively formed on one side of each bus bar frame 400 formed on the front surface / rear surface of the battery cell stack 100, so that the sensed voltage and temperature can be transmitted to the BMS in two directions through the connector formed on each bus bar frame 400 without the need to separately assemble a flexible flat cable. As a result, the manufacturing cost of the battery module can be reduced and the battery module structure can be simplified. In addition, the assembly process of the flexible flat cable and the process of checking the connection defects are removed, thereby simplifying the battery module manufacturing process.

[0042] The battery cell stack 100 is disposed in the module frame 200. According to the present embodiment, the module frame 200 may include a lower frame 210 covering a lower surface and both sides of the battery cell stack 100 and an upper plate 220 covering an upper surface of the battery cell stack 100.

[0043] In a state where the bus bar frame 400 is mounted on the front / rear surface of the battery cell stack 100, the battery cell stack 100 may be set to the lower frame 210. Thereafter, the upper plate 220 may be assembled to cover a portion of the battery cell stack 100. At this time, by fixing the upper plate 220 and the lower frame 210, the battery pack 100 may be stably set within the module frame 200.

[0044] The lower frame 210 of the module frame 200 accommodating the battery cell stack 100 may be a U-shaped frame. The U-shaped frame 210 may include a bottom 210a and two side portions 210b extending upward from both ends of the bottom 210a. The bottom 210a may cover the lower surface of the battery cell stack 100 (in the direction opposite to the z-axis), and the side portions 210b may cover both sides of the battery cell stack 100 (in the x-axis direction and in the direction opposite to the x-axis direction).

[0045] The upper plate 220 may be formed as a single plate-like structure surrounding the upper surface (z-axis direction) except for the lower surface and the two sides covered by the U-shaped frame 210. The upper plate 220 and the U-shaped frame 210 may form a structure that covers the battery cell stack 100 from top to bottom, left to right, and contacts each other at corresponding corners by being joined by welding or the like. The battery cell stack 100 may be physically protected by the upper plate 220 and the U-shaped frame 210. To this end, the upper plate 220 and the U-shaped frame 210 may include a metal material having a predetermined strength.

[0046] As previously referenced Figure 1 and Figure 2 As described above, in a state where the battery cell stack 100 is installed inside the module frame 200, welding can be performed to join the U-shaped frame 210 with the upper plate 220 of the module frame 200. At this time, in order to form a welded portion, the U-shaped frame 210 and the upper plate 220 need to be fixed so that the side portion 210b of the U-shaped frame 210 and the joining surface of the upper plate 220 are located at positions corresponding to each other. However, fixing the U-shaped frame 210 and the upper plate 220 in close correspondence with each other is limited, and there is a problem that welding cannot be performed smoothly.

[0047] In addition, laser welding may be performed for welding, and the laser itself or weld spatters that penetrate during welding may cause damage to internal components including battery cells. At this time, if an assembly defect occurs during the assembly process in which the upper plate 220 is placed on the U-shaped frame 210, the welding line is also misaligned, in which case a large amount of weld spatter flows into the battery module where the battery cell is located, thereby causing problems.

[0048] In order to reduce this problem, the battery module according to the present embodiment includes a lower frame having a protruding type assembly guide structure, thereby improving the assembly of the lower frame and the upper plate, thereby preventing welding defects. Figure 4 and Figure 5 Describe this in detail.

[0049] Figure 4 It is shown Figure 3 A perspective view of a lower frame included in a battery module. Figure 5 is a partial perspective view showing an assembly portion of an upper plate and a lower frame in a battery module according to an embodiment of the present invention.

[0050] refer to Figure 4 , the upper corner of the side 210b of the U-shaped frame 210 according to the present embodiment may form an assembly guide 210G. The assembly guide 210G may be formed as at least one on the upper corner of the side 210b of the U-shaped frame 210. A plurality of assembly guides 210G may be formed to be spaced apart from each other while having a predetermined interval therebetween.

[0051] The assembly guide portion 210G according to the present embodiment may include a protrusion-shaped support portion 210P protruding in the z-axis direction and recessed portions 210D formed on both sides of the support portion 210P. The recessed portion 210D may have an avoidance shape in which the upper corner of the side portion 210b of the U-shaped frame 210 is recessed in the opposite direction of the z-axis.

[0052] refer to Figure 5 According to the present embodiment, a groove portion 220D corresponding to the assembly guide portion 210G formed on the U-shaped frame 210 may be formed on the upper plate 220. The groove portion 220D may have a structure in which two corners of the upper plate 220 are recessed in directions facing each other so that the assembly guide portion 210G of the U-shaped frame 210 may be assembled with the upper plate 220. In this case, avoidance portions 220P may be formed at both ends of the groove portion 220D. The avoidance portions 220P minimize the gap of the groove portion 220D so that the support portion 210P of the assembly guide portion 210G may be accurately coupled to the groove portion 220D.

[0053] According to the present embodiment, by fixing the positions in the x-axis direction and the y-axis direction, not only the assemblability but also the durability of the battery module can be improved.

[0054] like Figure 3 As shown, similar to the battery cell stack 100 according to the embodiment of the present invention, when the number of stacked battery cells 110 is greater than Figure 2In the case of a large-area module with a large number of battery cells 11 in the battery cell stack 12 shown, the horizontal length of the battery module becomes longer. In a large-area module, since the horizontal length of the battery module increases, the load at the center is large and the possibility of bending deformation increases. Here, the horizontal length may refer to the length in the direction in which the battery cells are stacked. Due to the bending deformation, the coupling structure of the U-shaped frame 210 and the upper plate 220 may be deformed depending on the battery module usage conditions, but according to the present embodiment, by fixing the U-shaped frame 210 and the upper plate 220 in a solid position in both the x-axis direction and the y-axis direction, the coupling retention force between the U-shaped frame 210 and the upper plate 220 can be improved.

[0055] Reference again Figure 3 , the battery module according to the present embodiment may further include an end plate 600 covering the front surface / rear surface of the battery cell stack 100. The battery cell stack 100 disposed inside may be physically protected by the above-mentioned module frame 200. The end plate 600 may be located at the front (opposite direction of the y-axis) and the rear (y-axis direction) of the battery cell stack 100. The end plate 600 is formed to cover the battery cell stack 100, and may physically protect the battery cell stack 100 and other electronic devices from external impacts.

[0056] Meanwhile, although not specifically shown, the bus bar frame 400 on which the bus bars 411 are mounted and an insulation cover for electrical insulation, etc. may be located between the battery cell stack 100 and the end plate 600 .

[0057] On the other hand, one or more battery modules according to an embodiment of the present invention may be packaged in a battery pack case to form a battery pack. A battery pack may be formed by installing at least one battery module together with various control and protection systems such as a battery management system (BMS) and a cooling system.

[0058] The battery module and the battery pack including the battery module described above can be applied to various devices. The device can be applied to vehicles such as electric bicycles, electric vehicles, and hybrid vehicles, but is not limited thereto, and can be applied to various devices that can use secondary batteries.

[0059] While the invention has been described in conjunction with what are presently considered to be practical embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0060] [Description of Reference Numerals]

[0061] 200: Module Framework

[0062] 210: Lower frame

[0063] 210G: Assembly guide

[0064] 210P: Support part

[0065] 210D: Depression

[0066] 220: On the board

[0067] 220D: Groove

[0068] 220P: Avoidance

Claims

1. A battery module, comprising: a battery cell stack in which a plurality of battery cells are stacked; a module frame surrounding the battery cell stack; a bus bar frame covering a front surface and a rear surface of the battery cell stack exposed from the module frame; as well as an end plate covering the busbar frame, The module frame includes a lower frame covering the lower part and both sides of the battery cell stack and an upper plate covering the upper part of the battery cell stack, and At least one assembly guide is formed at a corner of the lower frame to which the upper plate is joined, The assembly guide portion includes a protrusion-shaped support portion protruding in one direction and recessed portions formed on both sides of the support portion. wherein a groove portion is formed on the upper plate, and the support portion of the assembly guide portion is assembled into the groove portion, The assembly guide can prevent welding defects caused by welding spatter flowing into the battery module during the module frame welding process.

2. The battery module according to claim 1, wherein: The lower frame includes: a bottom portion supporting the lower portion of the battery cell stack; and two side portions extending upward from both ends of the bottom portion, and The fitting guide portion is formed at a corner portion of an upper end of the side portion.

3. The battery module according to claim 1, wherein: The recessed portion has a relief shape in which an upper end corner portion of a side portion of the lower frame is recessed in a direction toward a bottom portion of the lower frame.

4. The battery module according to claim 1, wherein: The groove portion has a structure in which two corresponding corners of the upper plate are recessed in directions opposite to each other.

5. The battery module according to claim 4, wherein: Avoidance portions are formed on both ends of the groove portion. 6 . A battery pack comprising the battery module according to claim 1 .

Images