Battery pack

Abstract

The present invention discloses a battery pack. The battery pack comprises a plurality of battery cells and a bus bar electrically connected to the plurality of battery cells. The bus bar comprises a single layer and a multilayer portion, each comprising a different number of stackings along the thickness direction. The single layer comprises a first material layer, and the multilayer portion comprises a first material layer continuously connected from the first material layer of the single layer and a second material layer formed on at least one surface among the surface and back surface of the first material layer. According to the battery pack of the present invention, it may include a bus bar with an improved structure that can ensure the durability of the bus bar while forming a robust bond between the same metals as the counterpart connection target.

Description

Technology Field

[0001] The present invention relates to a battery pack. Background Technology

[0002] Generally, unlike primary batteries which cannot be recharged, secondary batteries are capable of both charging and discharging. Secondary batteries are used as energy sources for mobile devices, electric vehicles, hybrid vehicles, electric bicycles, and uninterruptible power supplies. Depending on the type of external device to which they are applied, they may be used in the form of a single battery cell or as a battery pack consisting of multiple connected cells bundled into a single unit.

[0003] While small mobile devices such as mobile phones can operate for a set period of time with the output and capacity of a single battery, battery packs are preferred for applications requiring long-term or high-power operation, such as electric and hybrid vehicles with high power consumption, due to output and capacity limitations; battery packs can increase output voltage or output current depending on the number of built-in battery cells.

[0004] In such a battery pack, a protection circuit module may be provided to collect state information of the battery cells, such as voltage and temperature, and to control the charging and discharging operations of the battery cells, for the purpose of detecting abnormal operation of the battery cells and taking protection operations. The problem to be solved

[0005] One embodiment of the present invention may include a bus bar with an improved structure that can ensure the durability of the bus bar while forming a strong bond between the same metals as the counterpart connection target. means of solving the problem

[0006] In order to solve the above problems and other problems, the battery pack of the present invention is,

[0007] It includes a plurality of battery cells and a bus bar electrically connected to the plurality of battery cells, and

[0008] The above bus bar comprises a single layer and a multilayer portion having a different number of layers along the thickness direction, wherein the single layer comprises a first material layer, and the multilayer portion may comprise a first material layer continuously connected from the first material layer of the single layer and a second material layer formed on at least one surface among the surface and back surface of the first material layer.

[0009] For example, the above bus bar has at least one of the single layer and the multi layer,

[0010] i) a first connection position connected to the electrode of the battery cell, and

[0011] ii) a second connection position connected to a circuit board disposed on the electrode of the battery cell, and

[0012] iii) It may be positioned to correspond to at least one of the third connection locations connected to a connection member extending to a position outside the battery cell.

[0013] For example, the above single layer may be placed at a first connection position, and the above multilayer may be placed at a second and third connection position of the bus bar.

[0014] For example, a first connection portion facing the electrode of a battery cell at the first connection position includes a first connection surface facing the electrode of the battery cell and a first back surface opposite to the electrode of the battery cell.

[0015] The first connection surface and the first back surface may be formed as the first material layer.

[0016] For example, the first connection surface is formed entirely of a first material layer, and

[0017] The above-mentioned first surface may be partially formed as a first material layer.

[0018] For example, the central region corresponding to the first connection position among the first surfaces is formed of a first material layer, and

[0019] Among the first surfaces above, the border area surrounding the central area can be formed as a second material layer.

[0020] For example, the central region above is provided as the surface of the single layer, and

[0021] The above border area can be provided as the surface of the multilayer section.

[0022] For example, a second connection portion facing the circuit board at the second connection position includes a second connection surface facing the circuit board and a second back surface opposite to the circuit board, and

[0023] The above second connection surface is formed of a second material layer, and

[0024] The above second surface can be formed as a first material layer.

[0025] For example, the second connection surface and the second back surface may be provided as opposite surfaces of the multilayer portion.

[0026] For example, a third connection portion facing the connecting member at the third connection position includes a third connection surface facing the connecting member and a third rear surface opposite to the connecting member, and

[0027] The above third connection surface is formed of the above second material layer, and

[0028] The above third surface can be formed as the above first material layer.

[0029] For example, the third connection surface is formed entirely of a second material layer, and

[0030] The above third surface can be formed entirely of the first material layer.

[0031] For example, the third connection surface and the third back surface may be provided as opposite surfaces of the multilayer portion.

[0032] For example, the first connection position and the second connection position may be formed on the main body of the bus bar, and the third connection position may be formed on the end of a measuring terminal that protrudes from the main body of the bus bar to face the circuit board.

[0033] For example, the above-mentioned measuring terminal may be formed as a multilayer portion including a second material layer formed on a first material layer.

[0034] For example, the above bus bar is,

[0035] A first bus bar comprising a main body formed at a first connection position and a measuring terminal formed at a second connection position, and

[0036] It may include a second bus bar comprising a main body formed at the first and third connection positions and a measuring terminal formed at the second connection position.

[0037] For example, the first bus bar may include first connection portions on both sides connected to the electrodes of different battery cells and a connection portion between the first connection portions on both sides.

[0038] For example, the above connection includes a surface facing the battery cell and a back surface opposite to the battery cell, and

[0039] The surface of the above-mentioned connection part is formed of the above-mentioned first material layer, and

[0040] The back surface of the above-mentioned connection part may be formed as a second material layer.

[0041] For example, the second bus bar may include a first connection part connected to an electrode of a first battery cell forming one end of an electrical connection of a plurality of battery cells, and a third connection part connected to a connecting member.

[0042] For example, the first material layer extends continuously from a single layer to a multilayer, and the thickness of the first material layer included in the single layer may be formed to be thinner than the thickness of the first material layer included in the multilayer.

[0043] For example, the first material layer comprises aluminum, and

[0044] The above second material layer may include copper. Effects of the invention

[0045] The battery pack of the present invention may include a bus bar with an improved structure that ensures the durability of the bus bar while forming a robust bond between the same metals with the counterpart connection target. Accordingly, according to the present invention, the resistance between different battery cells electrically connected by the bus bar and the resistance of the input / output lines of a plurality of electrically connected battery cells are reduced, thereby improving the output of the entire battery pack. Furthermore, by reducing the resistance of the transmission line of the state information received through the bus bar, distortion or deformation of the state information is prevented, thereby allowing for accurate determination of the state of the battery cells and suppressing delamination between different material layers in the bus bar which includes stacking of different material layers. Brief explanation of the drawing

[0046] FIG. 1 shows an exploded perspective view of a battery pack according to one embodiment of the present invention. Figure 2 shows a diagram illustrating the connection structure of the first bus bar illustrated in Figure 1. Figure 3a shows a cross-sectional view taken along line IIIa-IIIa of Figure 2. Figure 3b shows a cross-sectional view taken along the line IIIb-IIIb of Figure 2. Figure 4 shows a diagram illustrating the connection structure of the second bus bar illustrated in Figure 1. Figure 5a shows a cross-sectional view taken along the Va-Va line of Figure 4. Figure 5b shows a cross-sectional view taken along the line Vb-Vb of Figure 4. FIG. 6 shows a cross-sectional view according to a modified embodiment of the first bus bar shown in FIG. 3a. Specific details for implementing the invention

[0047] Hereinafter, a battery pack according to a preferred embodiment of the present invention will be described with reference to the attached drawings.

[0048] FIG. 1 shows an exploded perspective view of a battery pack according to an embodiment of the present invention. FIG. 2 shows a diagram showing the connection structure of the first bus bar shown in FIG. 1. FIG. 3a shows a cross-sectional view taken along the line IIIa-IIIa of FIG. 2. FIG. 3b shows a cross-sectional view taken along the line IIIb-IIIb of FIG. 2. FIG. 4 shows a diagram showing the connection structure of the second bus bar shown in FIG. 1. FIG. 5a shows a cross-sectional view taken along the line Va-Va of FIG. 4. FIG. 5b shows a cross-sectional view taken along the line Vb-Vb of FIG. 4. FIG. 6 shows a cross-sectional view according to a modified embodiment of the first bus bar shown in FIG. 3a.

[0049] Referring to the drawings, in one embodiment of the present invention, the battery pack may include a plurality of battery cells (10) arranged along a first direction (Z1). Although not illustrated in the drawings, in one embodiment of the present invention, the battery cell (10) may include an electrode assembly and a case surrounding the electrode assembly, and may include an electrode (15) electrically connected to the electrode assembly and drawn out onto the case. In one embodiment of the present invention, the electrode assembly may include first and second electrode plates alternately stacked and a separator interposed between the first and second electrode plates, and the first and second electrode plates alternately stacked with the separator may be wound into a roll shape or formed into a stack shape in which the first and second electrode plates are alternately stacked with the separator. The first and second electrode plates of the above electrode assembly can be electrically connected to the first and second electrodes (15a, 15b) formed on the case of the battery cell (10), and the charging and discharging of the electrode assembly can be performed through the first and second electrodes (15a, 15b) formed on the case of the battery cell (10).

[0050] A battery pack according to one embodiment of the present invention may include a plurality of battery cells (10) arranged along a first direction (Z1), and the plurality of battery cells (10) arranged along the first direction (Z1) may be electrically connected to each other through a bus bar (30). In one embodiment of the present invention, the battery pack may include a row of battery cells (10) arranged along the first direction (Z1), and in various embodiments of the present invention, the battery pack may have a row of battery cells (10) arranged along the first direction (Z1) arranged in at least two rows along a second direction (Z2) that intersects the first direction (Z1).

[0051] The above plurality of battery cells (10) may be electrically connected to each other through a bus bar (30). For example, the bus bar (30) may form a parallel connection by connecting the same electrodes (15) of different battery cells (10) to each other, or form a series connection by connecting the different electrodes (15) of different battery cells (10). In one embodiment of the present invention, battery cells (10) adjacent to each other along a first direction (Z1) may form a parallel connection by connecting the same electrodes (15) to each other, or battery cells (10) adjacent to each other along a first direction (Z1) may form a series connection by connecting the different electrodes (15) to each other. For example, in one embodiment of the present invention, the plurality of battery cells (10) may form a parallel connection by connecting the same electrodes (15) to each other along a first direction (Z1) such that the battery cells (10) adjacent to each other are arranged with the same orientation on the left and right sides along a second direction (Z2) that intersects the first direction (Z1). Alternatively, the plurality of battery cells (10) may be connected to each other along different electrodes (15) such that the battery cells (10) adjacent to each other along the first direction (Z1) are arranged with the left and right sides reversed along a second direction (Z2) that intersects the first direction (Z1). In various embodiments of the present invention, the plurality of battery cells (10) arranged along the first direction (Z1) may be connected in a parallel connection, a series connection, or a mixed series-parallel connection, and the number of battery cells (10) forming the battery pack, the number of parallel connections, and the number of series connections may be determined according to the required capacity and output of a set device that uses the battery pack as a power source.

[0052] In accordance with the present specification, the first direction (Z1) may refer to the front-to-back direction in which a plurality of battery cells (10) are arranged, and the second direction (Z2) may refer to a direction intersecting the first direction (Z1), for example, a left-to-right direction in which the first and second electrodes (15a, 15b) are arranged. Additionally, the third direction (Z3) may refer to a direction intersecting the first and second directions (Z1, Z2), for example, a height direction intersecting the surface in which a plurality of battery cells (10) are arranged.

[0053] In one embodiment of the present invention, the bus bar (30) may be positioned above the battery cell (10) along a third direction (Z3). In various embodiments of the present invention, a bus bar holder (20) may be positioned on the battery cell (10), and a plurality of bus bars (30) may be positioned on the bus bar holder (20) so that the positions of the bus bars (30) can be aligned in a correct position. For example, the bus bar holder (20) may be interposed between the battery cell (10) and the bus bar (30) along the third direction (Z3) to electrically insulate them from each other.

[0054] The above bus bar (30) may include a first bus bar (31) that mediates an electrical connection between different battery cells (10) and a second bus bar (32) that mediates an electrical connection between a plurality of battery cells (10) arranged along a first direction (Z1) and a connecting member (80). That is, throughout this specification, the term bus bar (30) does not limit itself to the first bus bar (31) that mediates an electrical connection between different battery cells (10), but comprehensively refers to a configuration that is electrically connected to a battery cell (10) to form a charging and discharging path for the battery cell (10). That is, in one embodiment of the present invention, the term bus bar (30) comprehensively refers to a configuration that is electrically connected to a battery cell (10) for electrical conduction with the battery cell (10). More specifically, among the bus bars (30), the first bus bar (31) may refer to a bus bar (30) that electrically connects different battery cells (10), and among the bus bars (30), the second bus bar (32) may refer to a bus bar (30) that is electrically connected to the first and second battery cells (11, 12) forming both ends of the electrical connection of the battery cells (10) arranged along the first direction (Z1), and is electrically connected to the first and second battery cells (11, 12) to form a charging and discharging path between the first and second battery cells (11, 12) and the connecting member (80).Throughout the present specification, the connecting member (80) refers to a member that extends to a location outside the battery cell (10) and is connected to a battery management unit (not shown, BMS, Battery Management System) or to another battery pack, and may refer to a member that connects the first and second battery cells (11, 12) and the battery management unit (not shown) or connects the first and second battery cells (11, 12) and another battery pack.

[0055] The bus bar holder (20) may include a bus bar area where a bus bar (30) is placed and a substrate area where a circuit board (50) electrically connected to the bus bar (30) is placed. For example, the bus bar holder (20) may include a bus bar area on both sides where a bus bar (30) is placed along the second direction (Z2) and a substrate area where a circuit board (50) is placed between the bus bar areas on both sides. The bus bar area is an area where a bus bar (30) connected to the first and second electrodes (15a, 15b) of a battery cell (10) placed at both sides along the second direction (Z2) is assembled, and may be formed in the edge areas on both sides along the second direction (Z2) within the bus bar holder (20). The above substrate area is a region in which a circuit board (50) connected to a bus bar (30) is placed, positioned at a central location along the second direction (Z2), and can be formed in the central region along the second direction (Z2) among the bus bar holders (20). For example, the above substrate area can be formed in the central region between the bus bar areas formed at the edge regions on both sides along the second direction (Z2).

[0056] In one embodiment of the present invention, the fact that the bus bar (30) and the circuit board (50) are electrically connected to each other may mean that state information of the battery cell (10) is obtained through the bus bar (30) which is electrically and thermally connected to the battery cell (10). For example, in one embodiment of the present invention, the circuit board (50) may collect state information such as temperature, current, and voltage of each battery cell (10) from at least some of the battery cells (10) among a plurality of battery cells (10) arranged along a first direction (Z1), and the battery pack may further include a battery management unit (not shown, BMS, Battery Management System) that receives state information collected from the battery cells (10) and controls the charging and discharging operation of the battery cell (10) based thereon.

[0057] In one embodiment of the present invention, the electrical connection between the bus bar (30) and the circuit board (50) may be made in such a way that a measurement terminal (30b) formed on the bus bar (30) is directly connected to the circuit board (50). For example, rather than the bus bar (30) and the circuit board (50) being connected through a separate connecting member (not shown) between them, the electrical connection between the bus bar (30) and the circuit board (50) may be made in such a way that a measurement terminal (30b), formed integrally with the bus bar (30) as part of the bus bar (30), is directly connected to the circuit board (50). In one embodiment of the present invention, both the first bus bar (31) and the second bus bar (32) may include a measurement terminal (30b) connected to the circuit board (50), and, for example, may be directly connected to the circuit board (50) through a fastening member (not shown) that is inserted through a measurement hole formed in the measurement terminal (30b). For example, the fastening member (not shown) can be fastened to a coupling hole (not shown) of the bus bar holder (20) by penetrating the measurement terminal (30b) and the circuit board (50) which are arranged to overlap each other on the bus bar holder (20), and the measurement terminal (30b) and the circuit board (50) can be electrically connected to each other by applying pressure contact to each other through the fastening member (not shown), so that the measurement terminal (30b) and the circuit board (50), for example, the pad (55) of the circuit board (50) can be electrically connected to each other. For example, the contact resistance between the measurement terminal (30b) and the pad (55) of the circuit board (50) can cause a measurement error regarding the state information of the battery cell (10) received through the measurement terminal (30b), and for example, can cause deformation or distortion of the state information of the battery cell (10) received through the measurement terminal (30b). In one embodiment of the present invention, for the purpose of reducing contact resistance between the measurement terminal (30b) and the circuit board (50), contact between the same metals can be formed between the measurement terminal (30b) and the circuit board (50).As described below, the bus bar (30) may include a first material layer (M1) formed over the entire bus bar (30) to form the framework of the bus bar (30), and a second material layer (M2) formed over a part of the bus bar (30) on the first material layer (M1). A second material layer (M2) formed of the same metal as the pad (55) of the circuit board (50) may be formed at the measurement terminal (30b) of the bus bar (30).

[0058] Hereinafter, the structure of a bus bar (30) applicable in one embodiment of the present invention will be described. The bus bar (30) described below forms a charging and discharging path for a battery cell (10) and may include a first bus bar (31) that forms a charging and discharging path between different battery cells (10), and a second bus bar (32) that forms a charging and discharging path between a first and second battery cell (11, 12) and a connecting member (80) that forms both ends of the electrical connection of the battery cell (10).

[0059] The bus bar (30) may include a first material layer (M1) forming the frame of the bus bar (30) and a second material layer (M2) formed on the first material layer (M1). The first material layer (M1) may be formed over the entire bus bar (30) to form the frame of the bus bar (30), and the second material layer (M2) may be formed on the first material layer (M1), but rather than being formed entirely on the first material layer (M1), it may be formed partially in a selected area of ​​the first material layer (M1). In one embodiment of the present invention, the bus bar (30) may include a first material layer (M1) and a second material layer (M2) formed on the first material layer (M1). Depending on the formation of the first and second material layers (M1, M2), the bus bar may include a single layer formed by the first material layer (M1) and a multilayer section including the first and second material layers (M1, M2) stacked relative to each other. As described below, the bus bar (30) may include a single layer including only the first material layer (M1) and a multilayer section including the stacking of the first and second material layers (M1, M2) depending on the position.

[0060] Hereinafter, the first to third connection positions (P1, P2, P3) of the bus bar (30) in one embodiment of the present invention will be described. The first to third connection positions (P1, P2, P3) of the bus bar (30) may refer to connection positions with the electrode (15) of the battery cell (10), the circuit board (50), and the connecting member (80) that are electrically connected to the bus bar (30). In other words, the bus bar (30) may be connected to the electrode (15) of the battery cell (10) through the first connection position (P1), connected to the circuit board (50) through the second connection position (P2), and electrically connected to the connecting member (80) through the third connection position (P3). Throughout this specification, the connecting member (80) may refer to a member extending to a location away from the battery cell (10), and may mean a member that electrically connects a plurality of battery cells (10) forming a battery pack with an external load (or external charger) or a plurality of battery cells (10) forming a battery pack with another battery pack. In one embodiment of the present invention, the connecting member (80) may extend from an area where a plurality of battery cells (10) are arranged, that is, from a first battery cell (11) to a location away from the battery cell (10).

[0061] The bus bar (30) of the present invention may include a single layer and a multilayer section comprising a different number of layers along the thickness direction, and may include a single layer section comprising a first material layer (M1) and a multilayer section comprising a second material layer (M2) formed on the first material layer (M1) and continuously extending from the first material layer (M1) of the single layer section. The above bus bar (30) can connect different battery cells (10) or connect between a battery cell (10) or between a circuit board (50) or between a first and second battery cell (11, 12) and a connecting member (80) forming both ends of the electrical connection of the battery cell (10), while forming first to third connection positions (P1, P2, P3) with different components surrounding the bus bar (30). Accordingly, each bus bar (30) may include at least two connection positions among the different first to third connection positions (P1, P2, P3). For example, a first bus bar (31) connecting different battery cells (10) may include different first connection positions (P1) connected to electrodes (15) of different battery cells (10), and a second bus bar (32) connecting the first and second battery cells (11, 12) and a connecting member (80) may each include a first connection position (P1) connected to the electrode (15) of the first battery cell (11) or the electrode (15) of the second battery cell (12), and a third connection position (P3) connected to the connecting member (80). At this time, the first bus bar (31) may include a main body (30a) including the first connection positions (P1) on both sides, and the second bus bar (32) may include a main body (30a) including the first connection position (P1) on one side and the third connection position (P3) on the other side.And, at least one of the first bus bar (31) and the second bus bar (32) may include a measuring terminal (30b) connected to the main body (30a), and the first bus bar (31) and / or the second bus bar (32) having the measuring terminal (30b) formed therein may further include a second connecting position (P2) in addition to the first and third connecting positions (P1, P3) as described above. In other words, in one embodiment of the present invention, the first bus bar (31) may include a main body (30a) including a first connection position (P1) on both sides and a measuring terminal (30b) extending from the main body (30a) and including a second connection position (P2), and the second bus bar (32) may include a main body (30a) including a first connection position (P1) on one side and a third connection position (P3) on the other side, and a measuring terminal (30b) extending from the main body (30a) and including a second connection position (P2).

[0062] That is, in one embodiment of the present invention, the first to third connection positions (P1, P2, P3) may each mean a position that forms a connection with a surrounding configuration connected to the bus bar (30) at a different location of the bus bar (30), and in one embodiment of the present invention, the first and second bus bars (31, 32) may each include two or more different connection positions, such as a first bus bar (31) including a first connection position (P1) on both sides and a second bus bar (32) including a first connection position (P1) on one side and a third connection position (P3) on the other side. For example, the first bus bar (31) may include two different connection positions, such as a first connection position (P1) on one side and another first connection position (P1) on the other side. As such, in one embodiment of the present invention, the first and second bus bars (31, 32) may include two different connection positions and additionally include a second connection position (P2) with the circuit board (50). For example, in one embodiment of the present invention, the first bus bar (31) may include three different connection positions in total, including two different first connection positions (P1) and a second connection position (P2), and the second bus bar (32) may include three different connection positions in total, including one first connection position (P1), a third connection position (P3), and a second connection position (P2). That is, in one embodiment of the present invention, each of the first and second bus bars (31, 32) may include two different connection positions, and at least one of the first and second bus bars (31, 32) may include three connection positions.

[0063] As described below, the first material layer (M1) or the second material layer (M2) can form opposite surfaces or reverse sides of the bus bar (30) at any of the first to third connection positions (P1, P2, P3), and can form a bond between the same metals with the battery cell (10), circuit board (50), and connection member (80) that are to be connected to the bus bar (30). In the following description, the first material layer (M1) or the second material layer (M2) forming the surface or back surface of the bus bar (30) at any of the first to third connection positions (P1, P2, P3) may mean that when the connection target of the bus bar (30) forms a connection toward the surface or back surface of the bus bar (30) where the first material layer (M1) or the second material layer (M2) is formed at the corresponding connection position, the first material layer (M1) or the second material layer (M2) forming the surface or back surface of the bus bar (30) and the connection target of the bus bar (30) face each other as metals of the same type, that is, the bus bar (30) and the connection target of the bus bar (30) face each other as the first material layer (M1) or the second material layer (M2) of the same type face each other, thereby forming a connection between metals of the same type. In accordance with the present specification, the fact that the first material layer (M1) forms the surface or back surface of the bus bar (30) may mean that the surface or back surface of the single layer portion including the first material layer (M1) is exposed to the outside of the bus bar (30), thereby forming a bond between the electrode (15) of the battery cell (10) formed by the first material layer (M1) and the same metal. For example, in one embodiment of the present invention, the first material layer (M1) and the electrode (15) of the battery cell (10) may be formed of the same aluminum material.

[0064] Additionally, according to the present specification, the second material layer (M2) forming the surface or back surface of the bus bar (30) may mean that the surface or back surface of the multilayer portion including the second material layer (M2) is exposed to the outside of the bus bar (30), thereby forming a bond between the same metal and the circuit board (50) or connecting member (80) formed by the second material layer (M2). For example, in one embodiment of the present invention, the second material layer (M2), the pad (55) of the circuit board (50), and the connecting member (80) may be formed of the same copper material.

[0065] When describing below the configuration of the first material layer (M1) or the second material layer (M2) that forms the surface or back side (connection surface or back side) of the bus bar (30) formed at any one of the first to third connection positions (P1, P2, P3), the statement that the first material layer (M1) forms the surface or back side of the bus bar (30) at the corresponding connection position may mean that the first material layer (M1) is exposed from the second material layer (M2) so that the first material layer (M1) forms the surface or back side of the bus bar (30). At this time, the bus bar (30) may be formed as a single layer portion that includes a first material layer (M1) at the corresponding connection location, but where a second material layer (M2) is not stacked on the first material layer (M1), and the first material layer (M1) on the surface or back side of the single layer portion of the bus bar (30) may be exposed to the outside of the bus bar (30).

[0066] When describing below the configuration of the first material layer (M1) or the second material layer (M2) that forms the surface or back side (connection surface or back side) of the bus bar (30) formed at any one of the first to third connection positions (P1, P2, P3) and the corresponding connection position, the statement that the second material layer (M2) forms the surface or back side of the bus bar (30) at the corresponding connection position may mean that the second material layer (M2) is exposed to the outside of the bus bar (30) and that the second material layer (M2) forms the surface or back side of the bus bar (30). At this time, the bus bar (30) may be formed as a multilayer portion including a first material layer (M1) and a second material layer (M2) stacked on the first material layer (M1) at the corresponding connection location, and the second material layer (M2) on the surface or back side of the multilayer portion of the bus bar (30) may be exposed to the outside of the bus bar (30).

[0067] In one embodiment of the present invention, the bus bar (30) of the first connection position (P1) may have a first connection portion (C1) comprising a first connection surface (surface of the first connection portion C1) facing the electrode (15) of the battery cell (10) to be connected at the first connection position (P1) and a first back surface (back surface of the first connection portion C1) opposite to the electrode (15) of the battery cell (10). Similarly, the bus bar (30) of the second connection position (P2) may have a second connection portion (C2) comprising a second connection surface (surface of the second connection portion C2) facing the circuit board (50) to be connected at the second connection position (P2) and a second back surface (back surface of the second connection portion C2) opposite to the circuit board (50). Similarly, the bus bar (30) of the third connection position (P3) may have a third connection part (C3) comprising a third connection surface (surface of the third connection part C3) facing the connection member (80) to be connected at the third connection position (P3) and a third back surface (back surface of the third connection part C3) opposite to the connection member (80).

[0068] Hereinafter, we will describe the configuration of each first to third connection surface (surface of the first to third connection portions C1, C2, C3) and the opposite first to third back surface (back surface of the first to third connection portions C1, C2, C3) forming the surface and back surface of the first to third connection portions (C1, C2, C3) of the first to third connection positions (P1, P2, P3), that is, the first material layer (M1) or the second material layer (M2) forming each first to third connection surface (surface of the first to third connection portions C1, C2, C3) and the opposite first to third back surface (back surface of the first to third connection portions C1, C2, C3). In the following description, the term "bus bar" (30) may exclusively refer to one of the first bus bar (31) that electrically connects different battery cells (10) and the second bus bar (32) that electrically connects the first and second battery cells (11, 12) forming the ends of the electrical connection of the battery cells (10) and the connecting member (80), or it may comprehensively refer to both the first and second bus bars (31, 32). For example, in relation to the first connection position (P1), the term "bus bar" (30) may refer to the first bus bar (31); in relation to the second connection position (P2), the term "bus bar" (30) may comprehensively refer to both the first and second bus bars (31, 32); and in relation to the third connection position (P3), the term "bus bar" (30) may refer to the second bus bar (32).

[0069] The above bus bar (30) may include a first connection part (C1) comprising a first connection surface (surface of the first connection part C1) facing the electrode (15) of the battery cell (10) at a first connection position (P1) and a first back surface (back surface of the first connection part C1) opposite to the first connection surface (surface of the first connection part C1). The first connection surface (surface of the first connection part C1) and the first back surface (back surface of the first connection part C1) may correspond to the surface of the first connection part (C1) exposed to the outside and may correspond to opposite surfaces of the first connection part (C1). As described below, the fact that the first connection surface (surface of the first connection part C1) is formed as a first material layer (M1) may mean that the first material layer (M1) is exposed through the first connection surface (surface of the first connection part C1) forming the surface of the first connection part (C1), and the fact that the first back surface (back surface of the first connection part C1) is formed as a first material layer (M1) may mean that the first material layer (M1) is exposed through the first back surface (back surface of the first connection part C1) forming the back surface of the first connection part (C1).

[0070] The first connection surface (surface of the first connection part C1) may be formed of a metal of the same type as the electrode (15) of the battery cell (10) to form a bond between the same type of metal with the electrode (15) of the battery cell (10). For example, the first connection surface (surface of the first connection part C1) may be formed entirely of a first material layer (M1). A first back surface (back surface of the first connection part C1) opposite to the first connection surface (surface of the first connection part C1) may be partially formed of the first material layer (M1). In one embodiment of the present invention, the first back surface (back surface of the first connection part C1) may include a central region formed of the first material layer (M1) and a border region formed of a second material layer (M2) different from the first material layer (M1), and the border region may be formed in a closed loop shape surrounding the central region. In accordance with the present specification, the center of the first back surface (the back surface of the first connection part C1) may mean the position where the first connection location (P1) is projected onto the first back surface (the back surface of the first connection part C1), and the central area of ​​the first back surface (the back surface of the first connection part C1) may mean a circular area centered on the first connection location (P1). In one embodiment of the present invention, the central area of ​​the first back surface (the back surface of the first connection part C1) may be provided as the surface of a single-layer part and formed as the first material layer (M1) of the single-layer part, and the edge area of ​​the first back surface (the back surface of the first connection part C1) may be provided as the surface of a multi-layer part and formed as the second material layer (M2) of the multi-layer part.

[0071] In one embodiment of the present invention, at least the first connection surface (surface of the first connection part C1) and the first back surface (back surface of the first connection part C1) centered on the first connection position (P1) are both formed of the first material layer (M1), thereby enabling the formation of a bond between the same metals with the electrode (15) of the battery cell (10) formed of the same type of first material layer (M1). For example, the first material layer (M1) and the electrode (15) of the battery cell (10) may include the same type of aluminum material.

[0072] That is, the central region of the first connection surface (surface of the first connection part C1) and the first back surface (back surface of the first connection part C1) centered on the first connection position (P1) can be provided as opposite surfaces of a single layer portion including the first material layer (M1), and accordingly, the first connection surface (surface of the first connection part C1) and the first back surface (back surface of the first connection part C1) can be formed of the first material layer (M1).

[0073] In one embodiment of the present invention, the connection between the bus bar (30) and the electrode (15) of the battery cell (10) can be made by thermal joining, such as welding. More specifically, in the connection between the bus bar (30) and the electrode (15) of the battery cell (10), welding energy can be introduced from the first back surface (the back surface of the first connection part C1) of the bus bar (30), and as the welding energy is introduced, the space between the first connection surface (the surface of the first connection part C1) and the electrode (15) of the battery cell (10) melts, and a welding area can be formed between the first connection surface (the surface of the first connection part C1) and the electrode (15) of the battery cell (10). Here, the fact that welding energy is supplied from the first back side (the back side of the first connection part C1) may mean, for example, that laser welding is performed while laser irradiation is performed from the first back side (the back side of the first connection part C1), or that welding current can be supplied from the first back side (the back side of the first connection part C1) through a welding rod in contact with the first back side (the back side of the first connection part C1), and thus, a welded joint can be formed between the electrode (15) of the battery cell (10) and the first connection surface (the surface of the first connection part C1) opposite to the first back side (the back side of the first connection part C1) by the welding energy supplied from the first back side (the back side of the first connection part C1). In one embodiment of the present invention, by forming the first back surface (back surface of the first connection part C1) into which welding energy is applied and the first connection surface (surface of the first connection part C1) that forms a connection with the electrode (15) of the battery cell (10) with the same first material layer (M1), a strong connection strength can be obtained through the connection between the electrode (15) of the battery cell (10) and the same metal.For example, if a second material layer (M2) different from the first material layer (M1) is formed on the first back side (the back side of the first connection part C1) where welding energy is applied, the second material layer (M2) and the first material layer (M1), which can be at least partially melted by the application of welding energy, are mixed, and an interfacial bond with weak bonding strength can be formed at the interface of these materials. That is, in one embodiment of the present invention, by forming the first connection surface (the surface of the first connection part C1) and the first back side (the central region of the back side of the first connection part C1) of the first connection part (C1) as the first material layer (M1) along the bonding depth, it is possible to prevent the formation of a bonding part in which different first and second material layers (M1, M2) are mixed by welding with a relatively deep bonding depth. As described below, unlike the first connection part (C1) which has a relatively deep connection depth, in the second connection part (C2) which has a relatively shallow connection depth, even if different first and second material layers (M1, M2) are mixed along the connection depth, it is possible to prevent the formation of a connection part in which different first and second material layers (M1, M2) are mixed by mechanical fastening or soldering with a relatively shallow connection depth. Therefore, even if the second connection surface (surface of the second connection part C2) and the second back surface (back surface of the second connection part C2) of the second connection part (C2) are formed with different first and second material layers (M1, M2) along the connection depth, a connection part in which different first and second material layers (M1, M2) are mixed by mechanical fastening or soldering with a relatively shallow connection depth can be prevented.

[0074] In one embodiment of the present invention, the first connection surface (surface of the first connection part C1) facing the electrode (15) of the battery cell (10) is formed entirely of the first material layer (M1), thereby enabling the formation of a bond between the same metals with the electrode (15) of the battery cell (10) through the first connection surface (surface of the first connection part C1). In this way, unlike the first connection surface (surface of the first connection part C1) facing the electrode (15) of the battery cell (10), the first back surface (back surface of the first connection part C1) opposite to the first connection surface (surface of the first connection part C1) is not formed entirely as the first material layer (M1), and the first material layer (M1) and the second material layer (M2) are formed in different central and edge regions. By forming the second material layer (M2) in the edge region, the second material layer (M2) of the first connection position (P1, second material layer M2 of the first back surface) and the second material layer (M2) of the second connection position (P2, second material layer M2 of the second connection surface) are formed to extend integrally through the second material layer (M2) formed in the edge region, thereby improving the peel strength between the first and second material layers (M1, M2) and preventing the second material layer (M2) of the bus bar (30) from peeling off from the first material layer (M1).

[0075] In this way, in one embodiment of the present invention, regarding the first connection position (P1) between the bus bar (30) and the electrode (15) of the battery cell (10), the first connection surface (surface of the first connection part C1) of the bus bar (30) facing the electrode (15) of the battery cell (10) is formed entirely of a first material layer (M1), and the first back surface (back surface of the first connection part C1) opposite to the first connection surface (surface of the first connection part C1) is formed of first and second material layers (M1, M2), thereby improving the bonding strength between the electrode (15) of the battery cell (10) and the bus bar (30), and at the same time, improving the peel strength between the first and second material layers (M1, M2) of the bus bar (30).

[0076] In one embodiment of the present invention, the bus bar (30) may include a second connection part (C2) comprising a second connection surface (surface of the second connection part C2) facing the circuit board (50) at a second connection position (P2) and a second back surface (back surface of the second connection part C2) opposite to the second connection surface (surface of the second connection part C2). The second connection part (C2) may form a part of a measurement terminal (30b) protruding from the main body (30a) of the bus bar (30) for coupling with the circuit board (50), for example, may form an end of the measurement terminal (30b) facing the circuit board (50). The second connection surface (surface of the second connection part C2) and the second back surface (back surface of the second connection part C2) may correspond to opposite surfaces of the second connection part (C2) exposed to the outside. As described below, the fact that the second connection surface (surface of the second connection part C2) is formed as a second material layer (M2) may mean that the second material layer (M2) is exposed through the second connection surface (surface of the second connection part C2) forming the surface of the second connection part (C2), and the fact that the second back surface (back surface of the second connection part C2) is formed as a first material layer (M1) may mean that the first material layer (M1) is exposed through the second back surface (back surface of the second connection part C2) forming the back surface of the second connection part (C2). In one embodiment of the present invention, the measuring terminal (30b) including the second connection part (C2) may be formed as a multilayer part including first and second material layers (M1, M2) stacked with respect to each other, and the second material layer (M2) and the first material layer (M1) may be exposed to the second connection surface (surface of the second connection part C2) and the second back surface (back surface of the second connection part C2), respectively, corresponding to the surface and back surface of the multilayer part.

[0077] In one embodiment of the present invention, the second connection surface (the surface of the second connection part C2) and the second back surface (the back surface of the second connection part C2) may each be formed with different second material layers (M2) and first material layers (M1). For example, in one embodiment of the present invention, the measurement terminal (30b) including the second connection part (C2) may protrude from the main body (30a) of the bus bar (30) with a relatively narrow width, and the measurement terminal (30b) protruding with a relatively narrow width may be formed as a multilayer part including the first and second material layers (M1, M2) overall, thereby improving the peel strength of the first and second material layers (M1, M2). That is, the measurement terminal (30b) can be formed as a multilayer portion including the first and second material layers (M1, M2) in total, including a second connection portion (C2) formed at its end, and by forming the measurement terminal (30b) that protrudes with a relatively narrow width from the main body (30a) of the bus bar (30) and has a limited contact area between the first and second material layers (M1, M2) in total as a multilayer portion including the first and second material layers (M1, M2), the peel strength between the first and second material layers (M1, M2) can be improved, and furthermore, the peel strength between the first and second material layers (M1, M2) can be further improved by forming the second material layer (M2) of the second connection position (P2, second material layer M2 of the second connection surface) and the second material layer (M2) of the first connection position (P1, second material layer M2 of the first back surface) continuously with each other.

[0078] The connection between the second connection portion (C2) of the bus bar (30) and the circuit board (50) can be achieved through mechanical fastening or thermal bonding, such as soldering, between the second connection portion (C2) of the bus bar (30) and the pad (55) of the circuit board (50). That is, in one embodiment of the present invention, the connection between the first connection portion (C1) of the bus bar (30) and the electrode (15) of the battery cell (10) at the first connection position (P1) can be achieved through thermal bonding, such as welding, which has a relatively deep connection depth, and the connection between the second connection portion (C2) of the bus bar (30) and the circuit board (50) at the second connection position (P2) can be achieved through mechanical fastening or thermal bonding, such as soldering, which has a relatively shallow connection depth. Through the present specification, the fact that the mechanical connection between the second connection part (C2) of the bus bar (30) and the circuit board (50) has a shallow connection depth may mean, for example, that the second connection part (C2) of the bus bar (30) and the pad (55) of the circuit board (50) do not form a connection in an integrated form by melting and fusing to the extent that they are indistinguishable from each other, or that even if the second connection part (C2) of the bus bar (30) and the pad (55) of the circuit board (50) form a connection in an integrated form by melting and fusing to the extent that they are indistinguishable from each other due to the mechanical connection force between the second connection part (C2) of the bus bar (30) and the pad (55) of the circuit board (50), the depth of the connection is shallow.

[0079] In various embodiments of the present invention, in addition to mechanical fastening, thermal bonding such as soldering may be applied between the second connection portion (C2) of the bus bar (50) and the circuit board (50). In this case, when soldering the second connection portion (C2), which has a relatively shallower bonding depth than the welding of the first connection portion (C1), that is, close to surface bonding, even if the first and second material layers (M1, M2) are mixed, a bonding portion in which the first and second material layers (M1, M2) are mixed may not be formed, and accordingly, defects in the bonding may not be caused. For example, in one embodiment of the present invention, at a first connection position (P1) with a relatively deep connection depth, the first connection surface (surface of the first connection part C1) and the first back surface (central area of ​​the first back surface), which respectively form the surface and back surface of the first connection part (C1), may be formed of the same first material layer (M1), and at a second connection position (P2) with a relatively shallow connection depth, the second connection surface (surface of the second connection part C2) and the second back surface (back surface of the second connection part C2), which respectively form the surface and back surface of the second connection part (C2), may be formed of different second material layers (M2) and first material layers (M1).

[0080] In one embodiment of the present invention, the second connection position (P2) may be formed on both the first and second bus bars (31, 32), and the second connection portion (C2) forming the connection with the circuit board (50) may be formed as a multilayer portion including the first and second material layers (M1, M2). In one embodiment of the present invention, the measurement terminal (30b) of the first bus bar (31) and the measurement terminal (30b) of the second bus bar (32) may both be formed as multilayer portions and may extend from the main body (30a) of the first bus bar (31) and the main body (30a) of the second bus bar (32), respectively, toward the third connection position (P3) facing the circuit board (50). In a specific embodiment of the present invention, the measurement terminal (30b) of the first bus bar (31) may be extended with a relatively narrow width from the main body (30a) of the first bus bar (31), and the measurement terminal (30b) of the second bus bar (32) may be extended with a relatively wide width from the main body (30a) of the second bus bar (32), but the structure of the measurement terminals (30b) of the first and second bus bars (31, 32) may all be formed as a multilayer section including a stack of the first and second material layers (M1, M2).

[0081] In one embodiment of the present invention, the bus bar (30) may include a third connection portion (C3) comprising a third connection surface (surface of the third connection portion C3) facing the connection member (80) at a third connection position (P3) and a third back surface (back surface of the third connection portion C3) opposite to the third connection surface (surface of the third connection portion C3). In one embodiment of the present invention, the connection member (80) may extend to a position away from the battery cell (10) to form a charging and discharging path connected to a plurality of battery cells (10) forming a battery pack. For example, the connection member (80) may connect between a first and second battery cell (11, 12) forming both ends of the electrical connection of the plurality of battery cells (10) and a battery management unit (not shown), or connect between the first and second battery cells (11, 12) and another battery pack. Here, the first and second battery cells (11, 12) may correspond to the battery cell having the highest potential (10, highest potential battery cell 10) and the battery cell having the lowest potential (10, lowest potential battery cell 10) among a plurality of battery cells (10) connected in series, and may correspond to the battery cell (10) having a relatively high potential and the battery cell (10) having a relatively low potential among a plurality of battery cells (10) connected in parallel. In one embodiment of the present invention, the third connection position (P3) may include a connection position between a bus bar (30) connected to the first battery cell (11) and a connection member (80), and a connection position between a bus bar (30) connected to the second battery cell (12) and a connection member (80), and the structure of the bus bar (30) at these third connection positions (P3) may be substantially the same.Hereinafter, the third connection position (P3) between the bus bar (30) connected to the first battery cell (11) and the connecting member (80) will be described in detail. Since the third connection position (P3) between the bus bar (30) connected to the second battery cell (12) and the connecting member (80) is substantially the same as the third connection position (P3) between the bus bar (30) connected to the first battery cell (11) and the connecting member (80) described below, a redundant description will be omitted.

[0082] The third connection surface (the surface of the third connection part C3) may be formed entirely of a second material layer (M2), and the third back surface (the back surface of the third connection part C3) may be formed entirely of a first material layer (M1). For example, the third connection part (C3) may be formed as a multilayer part including first and second material layers (M1, M2). At this time, the third connection surface (the surface of the third connection part C3) and the third back surface (the back surface of the third connection part C3), corresponding to the surface and back surface of the third connection part (C3), may be formed of the second material layer (M2) and the first material layer (M1), respectively.

[0083] The third connection surface (surface of the third connection part C3) is formed entirely of the second material layer (M2), thereby enabling the formation of a bond between the same metals with the connecting member (80) formed of the same type of second material layer (M2). For example, in one embodiment of the present invention, the second material layer (M2) and the connecting member (80) may include the same type of copper material. For example, the bond between the bus bar (30) and the connecting member (80) may be formed through thermal bonding such as welding. In the bond between the bus bar (30) and the connecting member (80), welding energy may be introduced from the surface of the connecting member (80), and as the welding energy is introduced, the area between the back surface of the connecting member (80) and the third connection surface (surface of the third connection part C3) melts, and a weld area may be formed between the back surface of the connecting member (80) and the third connection surface (surface of the third connection part C3). Here, the fact that welding energy is supplied from the surface of the connecting member (80) may mean, for example, that laser welding is performed by laser irradiation from the surface of the connecting member (80) or that welding current is input from the surface of the connecting member (80) through a welding rod in contact with the surface of the connecting member (80), and that a welded joint can be formed by melting the back surface of the connecting member (80) opposite to the surface of the connecting member (80) and the third connecting surface (the surface of the third connecting part C3) by the welding energy supplied from the surface of the connecting member (80). In one embodiment of the present invention, the third connecting surface (the surface of the third connecting part C3) that contacts the connecting member (80) into which welding energy is supplied may be formed with a second material layer (M2) of the same type as the connecting member (80), while the third back surface (the back surface of the third connecting part C3) that does not contact the connecting member (80) may be formed with a first material layer (M1) different from the connecting member (80).In one embodiment of the present invention, the connection between the bus bar (30) and the electrode (15) of the battery cell (10) at the first connection position (P1) or the connection between the bus bar (30) and the connecting member (80) at the third connection position (P3) may both be formed by welding with a relatively deep connection depth, but the first connection surface (surface of the first connection part C1) and the first back surface (back surface of the first connection part C1) corresponding to the first connection position (P1) may both be formed with a first material layer (M1) of the same type as the electrode (15) of the battery cell (10), while the third connection surface (surface of the third connection part C3) corresponding to the third connection position (P3) may be formed with a second material layer (M2) of the same type as the connecting member (80), and the third back surface (back surface of the third connection part C3) corresponding to the third connection position (P3) may be formed with a first material layer (M1) different from the connecting member (80).In this way, regarding the first connection position (P1) and the third connection position (P3) where a connection is formed through welding with a relatively deep connection depth, the structure of the first connection surface (surface of the first connection part C1) and the first back surface (back surface of the first connection part C1) at the first connection position (P1), and the structure of the third connection surface (surface of the third connection part C3) and the third back surface (back surface of the third connection part C3) at the third connection position (P3) are formed with different structures from each other. This is because, along the direction of welding energy input, welding energy is input to the first back surface (back surface of the first connection part C1) of the bus bar (30) ahead of the first connection surface (surface of the first connection part C1), whereas welding energy is input to the third back surface (back surface of the third connection part C3) of the bus bar (30) behind the third connection surface (surface of the third connection part C3) along the direction of welding energy input. Therefore, the first connection surface (first connection part) where welding is actually performed The first back surface (central area of ​​the first back surface) into which welding energy is applied prior to the surface of C1) is formed with the first material layer (M1) in accordance with the first connection surface (surface of the first connection part C1) formed with the first material layer (M1), but the third back surface (back surface of the third connection part C3) into which welding energy is applied following the third connection surface (surface of the third connection part C3) where welding is actually performed can be formed with the first material layer (M1), unlike the third connection surface (surface of the third connection part C3) formed with the second material layer (M2).In one embodiment of the present invention, the direction of welding energy input may be such that, when the electrode (15) or connecting member (80) of each battery cell 10) that is connected to the bus bar (30) at the first connection position (P1) and the third connection position (P3) overlap each other, welding energy may be input from the upper surface of the member formed relatively higher. For example, at the first connection position (P1), welding energy may be input from the first back surface (back surface of the first connection part C1) of the bus bar (30) formed on the electrode (15) of the battery cell (10), and at the third connection position (P3), welding energy may be input from the surface of the connecting member (80) placed on the third connection surface (surface of the third connection part C3) of the bus bar (30). After the battery pack is formed, the connecting member (80) is placed on the bus bar (30) formed in the battery pack, and since a connection can be made between the bus bar (30) and the connecting member (80), welding energy can be supplied from the surface of the connecting member (80) placed on the bus bar (30).

[0084] In one embodiment of the present invention, the third connection surface (the surface of the third connection part C3) may be formed entirely of a second material layer (M2), and the third back surface (the back surface of the third connection part C3) may be formed entirely of a first material layer (M1). At the third connection position (P3), the third back surface (the back surface of the third connection part C3) is formed entirely of a first material layer (M1), but alternatively, at the first connection position (P1), the first back surface (the back surface of the first connection part C1) may be formed in a form in which the first material layer (M1) and the second material layer (M2) are partially mixed with each other (the central region and the edge region of the first back surface). In other words, at the first connection position (P1), a part (central region) of the first back surface (back surface of the first connection part C1) can be formed as a first material layer (M1), and another part (edge ​​region) of the first back surface (back surface of the first connection part C1) can be formed as a second material layer (M2), so that the second material layer (M2) of the first connection position (P1, second material layer M2 of the first back surface) and the second material layer (M2) of the second connection position (P2, second material layer M2 of the second connection surface) are continuously connected to each other, thereby improving the peel strength of the second material layer (M2) formed on the first material layer (M1).

[0085] Unlike the first connection position (P1) above, the third back surface (the back surface of the third connection part C3) at the third connection position (P3) can be formed entirely of the first material layer (M1). In this way, even if the third back surface (the back surface of the third connection part C3) is formed entirely of the first material layer (M1), the second material layer (M2) of the second connection position (P2, the second material layer M2 of the second connection surface) and the second material layer (M2) of the third connection position (P3, the second material layer M2 of the third connection surface) are connected continuously to each other, thereby improving the peel strength between the first and second material layers (M1, M2) and improving the peel strength of the second material layer (M2) formed on the first material layer (M1). For example, at the first connection position (P1), the first connection surface (the surface of the first connection part C1) does not include the second material layer (M2), but the first back surface (the back surface of the first connection part C1) includes the second material layer (M2), so the second material layer (M2) of the first connection position (P1) and the second connection position (P2) can be formed in a form that is continuously connected to each other, and at the third connection position (P3), the third back surface (the back surface of the third connection part C3) does not include the second material layer (M2), but the third connection surface (the surface of the third connection part C3) includes the second material layer (M2), so the second material layer (M2) of the third connection position (P3) and the second connection position (P2) can be formed in a form that is continuously connected to each other. In this way, the second material layer (M2) of the different first to third connection positions (P1, P2, P3) is connected continuously to one another, thereby preventing the second material layer (M2) formed at the second connection position (P2), that is, the measurement terminal (30b) protruding from the main body (30a) of the bus bar (30), from peeling off.

[0086] In other words, in one embodiment of the present invention, the second bus bar (32) including the third connection position (P3) may include a main body (30a) of a bus bar (30) including a first part including the first connection position (P1) and another part including the third connection position (P3), and a measuring terminal (30b) including the second connection position (P2). At this time, the measuring terminal (30b) of the second bus bar (32) may protrude from the other side of the main body (30a) that includes the third connection position (P3). At this time, the other side of the main body (30a) of the second bus bar (32) that is connected to the connecting member (80) at the third connection position (P3) and the measuring terminal (30b) that protrudes from the other side of the main body (30a) and is connected to the circuit board (50) at the second connection position (P2) are formed as a multilayer portion including a stacking of the first and second material layers (M1, M2), and may include the second material layer (M2) on the surface and the first material layer (M1) on the back surface. Furthermore, the second material layer (M2) formed at the second and third connection positions (P3) may be continuously extended from each other.

[0087] The first and second bus bars (31, 32) may be formed with generally similar shapes, and for example, the first and second bus bars (31, 32) may each include a surface and a back surface formed from one of the first and second material layers (M1, M2) according to the first to third connection positions (P1, P2, P3) with different connection targets. However, at the first connection position (P1) of the first and second bus bars (31, 32) connected to the electrode (15) of the battery cell (10), the first back surface (back surface of the first connection part C1) formed at the first connection position (P1) of the first bus bar (31) includes a central area formed of the first material layer (M1) and a border area formed of the second material layer (M2), but the first back surface (back surface of the first connection part C1) formed at the first connection position (P1) of the second bus bar (32) may be formed entirely of the first material layer (M1). In one embodiment of the present invention, considering the peel strength of the first and second material layers (M1, M2), the formation of the first and second material layers (M1, M2) at the first back surface (back surface of the first connection part C1) of the first and second bus bars (31, 32) may be differentiated. That is, on the first back side of the first bus bar (31) (the back side of the first connection part C1), a continuous second material layer (M2) up to the second connection position (P2) can be formed through the second material layer (M2) formed on the edge area, and even if the second material layer (M2) is not formed on the first back side of the second bus bar (32) (the back side of the first connection part C1), a continuous second material layer (M2) up to the second connection position (P2) can be formed through the second material layer (M2) formed on the third connection surface (the surface of the third connection part C3). Therefore, unlike on the first back side of the first bus bar (31) (the back side of the first connection part C1), the second material layer (M2) may not be formed on the first back side of the second bus bar (32) (the back side of the first connection part C1).

[0088] In one embodiment of the present invention, the first and second bus bars (31, 32) may be formed with generally similar shapes. For example, the first and second bus bars (31, 32) may both include a first connection position (P1) connected to the electrode (15) of the battery and a second connection position (P2) connected to the circuit board (50). In one embodiment of the present invention, the first bus bar (31) may include a first connection position (P1) connected to the electrode (15) of the battery cell (10) on both sides, and the second bus bar (32) may include a first connection position (P1) connected to the electrode (15) of the battery cell (10) on one side, and a third connection position (P3) connected to the connecting member (80) on the other side. In one embodiment of the present invention, the first bus bar (31) may further include a first connection part (C1) formed at a first connection position (P1) on both sides and a connecting part (35) formed between the first connection parts (C1) on both sides. The connecting part (35) connects the first connection parts (C1) on both sides that are connected to the electrodes (15) of different battery cells (10), and, for example, may include a shape bent in the opposite direction of the battery cell (10) to align the positions of the first connection parts (C1) on both sides. For example, in one embodiment of the present invention, position alignment of the first bus bar (31) can be provided through the connection portion (35) of the first bus bar (31), for example, through alignment between the connection portion (35) of the first bus bar (31) and the bus bar holder (20), and position alignment between the first connection portion (C1) formed on both sides of the first bus bar (31) and the electrode (15) of the battery cell (10) can be provided. In one embodiment of the present invention, the first connection portion (C1) formed on both sides of the first bus bar (31) and the connection portion (35) formed between the first connection portion (C1) can form the main body (30a) of the first bus bar (31).Additionally, the first bus bar (31) may further include a measuring terminal (30b) that protrudes from the main body (30a) and extends to a second connection position (P2).

[0089] In one embodiment of the present invention, the connection portion (35) may be formed as a multilayer portion of the first bus bar (31) together with the edge area of ​​the first connection portion (C1). That is, the connection portion (35) may include a stack of first and second material layers (M1, M2), and, for example, may include a surface facing the battery cell (10) and a back surface opposite to the battery cell (10), and the surface of the connection portion (35) may be formed with the first material layer (M1), and the back surface of the connection portion (35) may be formed with the second material layer (M2).

[0090] As such, the first and second bus bars (31, 32) may have generally similar structures, but may include measuring terminals (30b) of different structures at a second connection position (P2) that protrudes from the main body (30a) of the first and second bus bars (31, 32) and is connected to the circuit board (50). For example, the measuring terminal (30b) of the first bus bar (31) may be formed with a relatively narrow width and may include a plurality of bent shapes along the third direction (Z3) corresponding to the height direction. Unlike the measuring terminal (30b) of the first bus bar (31), the measuring terminal (30b) of the second bus bar (32) may be formed with a relatively wide width and may include a simply bent shape that is simply bent once along the third direction (Z3) corresponding to the height direction. In this way, by forming the measurement terminals (30b) of the first and second bus bars (31, 32) that form a connection with the circuit board (50) at the second connection position (P2) in different shapes, particularly by forming the measurement terminal (30b) of the first bus bar (31) with a relatively narrow width and forming a plurality of bent shapes along the third direction (Z3) corresponding to the height direction, the circuit board (50) can be elastically supported through the measurement terminal (30b) of the first bus bar (31). For example, the circuit board (50) can be elastically supported from the bus bar holder (20) through a plurality of measurement terminals (30b) of the first bus bar (31) arranged along the long side of the circuit board (50). For example, in order to elastically support the circuit board (50), the measurement terminal (30b) of the first bus bar (31) is formed with a relatively thin width, and at the same time, a plurality of bent shapes are formed on the measurement terminal (30b), so that the measurement terminal (30b) of the first bus bar (31) can support the circuit board (50) and elastically support the circuit board (50).That is, the circuit board (50) can be elastically supported in a state lifted from the bus bar holder (20) through the measurement terminal (30b) of the first bus bar (31).

[0091] The measurement terminal (30b) of the second bus bar (32) can support the circuit board (50) at both ends along the longitudinal direction of the circuit board (50), but the circuit board (50) that receives sufficient support through the measurement terminal (30b) of the first bus bar (31) may receive relatively weak support through the measurement terminal (30b) of the second bus bar (32). Accordingly, the measurement terminal (30b) of the second bus bar (32) may be formed with a relatively wider width than the measurement terminal (30b) of the first bus bar (31), and even if it includes a bent shape for elastic support, there may be a difference in the number of bends. For example, the measurement terminals (30b) of the first and second bus bars (31, 32) can both support the circuit board (50), but the measurement terminal (30b) of the first bus bar (31) can support the circuit board (50) relatively elastically, and the measurement terminal (30b) of the second bus bar (32) can support the circuit board (50) relatively rigidly.

[0092] In one embodiment of the present invention, the bus bar (30) may include a first material layer (M1) formed over the entire bus bar (30) to form the skeleton of the bus bar (30), and a second material layer (M2) formed in a selective area on the first material layer (M1). The bus bar (30) may include a single-layer portion including the first material layer (M1) and a multi-layer portion including the first and second material layers (M1, M2) stacked relative to each other, and the single-layer portion and the multi-layer portion may be continuously connected relative to each other through the first material layer (M1) which extends continuously relative to each other. The first material layer (M1) may provide a common support base for the single-layer portion and the multi-layer portion. In one embodiment of the present invention, the single-layer portion of the bus bar (30) may be formed in the central area of ​​the first connection portion (C1), and the multi-layer portion of the bus bar (30) may be formed in the edge area of ​​the first connection portion (C1).

[0093] Hereinafter, with reference to FIG. 5b and FIG. 6, the step structure of the first material layer (M) will be described. In one embodiment of the present invention, the bus bar (30) may include a single layer portion formed by the first material layer (M1) and a multilayer portion including a stack of the first and second material layers (M1, M2). The first material layer (M1) of the single layer portion and the first material layer (M1) of the multilayer portion may be continuously connected to each other and formed into a stepped structure in which a step (d) is formed from each other along the thickness direction.

[0094] In the formation of a bus bar (30) according to one embodiment of the present invention, a connection between first and second material layers (M1, M2) stacked relative to each other is formed through a rolling process, and a bus bar (30) including a single layer portion at a first connection position (P1) and a multilayer portion at a second and third connection position (P3) can be formed by selectively removing a portion of the second material layer (M2) among the first and second material layers (M1, M2) stacked relative to each other. At this time, mechanical removal such as grinding or cutting, or chemical removal such as etching, may be applied to remove the second material layer (M2) from the first and second material layers (M1, M2) stacked relative to each other. And, along with the removal of the second material layer (M2), a portion of the first material layer (M1) is also removed, and a step (d) of the first material layer (M1) having different thicknesses along the thickness direction can be formed. That is, the first material layer (M1) is formed continuously relative to each other in the single-layer and multi-layer sections of the bus bar (30), but the first thickness, which is relatively thin in the single-layer section, and the second thickness, which is relatively thick in the multi-layer section, can be formed with different thicknesses relative to each other. In other words, the first thickness in the central region of the first connection section (C1) formed in the single-layer section of the bus bar (30) can be formed thinner than the second thickness in the edge region of the first connection section (C1) formed in the multi-layer section of the bus bar (30). In another embodiment of the present invention, the thickness of the first material layer (M1) may be formed equally in the single-layer section and the multi-layer section.

[0095] In one embodiment of the present invention, a single layer of the bus bar (30) may be formed in the central region of the first connection part (C1), and a multilayer of the bus bar (30) may be formed in the edge region of the first connection part (C1) and in the second and third connection parts (C2, C3). In one embodiment of the present invention, the first material layer (M1) of the single-layer portion is formed with a relatively thin first thickness, and the first material layer (M1) of the multi-layer portion is formed with a relatively thick second thickness. This may mean that a step (d) in the thickness direction is formed in the first material layer (M1) that extends continuously along the edge region of the first connection portion (C1) formed as a multi-layer portion and the central region of the first connection portion (C1) formed as a single-layer portion, and also that a step (d) in the thickness direction is formed in the first material layer (M1) that extends continuously along the third connection portion (C3) formed as a multi-layer portion and the first connection portion (C1) formed as a single-layer portion.

[0096] The present invention has been described with reference to the embodiments illustrated in the drawings, but this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true technical scope of protection of the present invention should be determined by the technical spirit of the appended claims. Explanation of the symbols

[0097] P1: First connection location P2: Second connection location P3: Third connection location C1: First connection part C2: Second connection part C3: Third connection part M1: First material layer M2: Second material layer 10: Battery cell 15: Electrode of the battery cell 20: Bus bar holder 30: Bus bar 31: 1st Bus Bar 32: 2nd Bus Bar 30a: Bus bar body 30b: Measurement terminal 35: Connection part 50: Circuit board 80: Connecting member

Claims

Claim 1 A battery pack comprising a plurality of battery cells and a bus bar electrically connected to the plurality of battery cells, wherein the bus bar comprises a single layer and a multilayer portion having a different number of stacks along the thickness direction, wherein the single layer comprises a first material layer, and the multilayer portion comprises a first material layer continuously connected from the first material layer of the single layer and a second material layer formed on at least one surface among the surface and back surface of the first material layer, wherein the single layer is disposed at a first connection position to form an electrical connection with an electrode of a battery cell, and the multilayer portion is disposed at at least one connection position among ii) a second connection position to form an electrical connection with a circuit board disposed on an electrode of a battery cell, or iii) a third connection position to form an electrical connection with a connection member extending to a position away from the battery cell. Claim 2 delete Claim 3 A battery pack according to claim 1, characterized in that the single layer is positioned at a first connection position, and the multi layer is positioned at a second connection position and a third connection position of the bus bar. Claim 4 A battery pack according to claim 1, wherein a first connection portion facing an electrode of a battery cell at the first connection position includes a first connection surface facing an electrode of the battery cell and a first back surface opposite to an electrode of the battery cell, and the first connection surface and the first back surface are formed of the first material layer. Claim 5 A battery pack according to claim 4, characterized in that the first connection surface is formed entirely of a first material layer, and the first back surface is partially formed of a first material layer. Claim 6 A battery pack according to claim 5, wherein the central region corresponding to the first connection position among the first surfaces is formed of a first material layer, and the border region surrounding the central region among the first surfaces is formed of a second material layer. Claim 7 A battery pack according to claim 6, characterized in that the central region is provided as the surface of a single layer and the rim region is provided as the surface of a multilayer. Claim 8 A battery pack according to claim 1, wherein the second connection portion facing the circuit board at the second connection position includes a second connection surface facing the circuit board and a second back surface opposite to the circuit board, wherein the second connection surface is formed of a second material layer and the second back surface is formed of a first material layer. Claim 9 A battery pack according to claim 8, characterized in that the second connection surface and the second back surface are provided as opposite surfaces of the multilayer portion. Claim 10 A battery pack according to claim 1, wherein the third connection portion facing the connecting member at the third connection position includes a third connection surface facing the connecting member and a third rear surface opposite to the connecting member, wherein the third connection surface is formed of the second material layer and the third rear surface is formed of the first material layer. Claim 11 A battery pack according to claim 10, characterized in that the third connection surface is formed entirely of a second material layer, and the third back surface is formed entirely of a first material layer. Claim 12 A battery pack according to claim 11, characterized in that the third connection surface and the third rear surface are provided as opposite surfaces of the multilayer portion. Claim 13 A battery pack according to claim 1, wherein the first connection position and the second connection position are formed on the main body of the bus bar, and the third connection position is formed on the end of a measurement terminal protruding from the main body of the bus bar to face the circuit board. Claim 14 A battery pack according to claim 13, wherein the measurement terminal is formed as a multilayer portion including a second material layer formed on a first material layer. Claim 15 A battery pack according to claim 1, wherein the bus bar comprises a first bus bar including a main body formed at a first connection position and a measuring terminal formed at a second connection position, and a second bus bar including a main body formed at a first and third connection position and a measuring terminal formed at a second connection position. Claim 16 A battery pack according to claim 15, wherein the first bus bar comprises a first connection portion on both sides connected to the electrodes of different battery cells and a connection portion between the first connection portions on both sides. Claim 17 A battery pack according to claim 16, wherein the connection portion comprises a surface facing the battery cell and a rear surface opposite to the battery cell, wherein the surface of the connection portion is formed of the first material layer and the rear surface of the connection portion is formed of the second material layer. Claim 18 A battery pack according to claim 15, wherein the second bus bar comprises a first connection part connected to an electrode of a first battery cell forming one end of an electrical connection of a plurality of battery cells, and a third connection part connected to a connecting member. Claim 19 A battery pack according to claim 1, wherein the first material layer extends continuously from a single layer to a multilayer, and the thickness of the first material layer included in the single layer is formed to be thinner than the thickness of the first material layer included in the multilayer. Claim 20 A battery pack according to claim 1, characterized in that the first material layer comprises aluminum and the second material layer comprises copper.

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