Battery pack

Abstract

Battery pack, including: a plurality of cylindrical battery cells (10) with battery terminals at opposite ends thereof, wherein the battery cells are arranged side by side in a pack configuration, such that a concave valley region is formed between pairs of adjacent battery cells; a printed circuit board (50) provided along a side surface of the pack configuration to control charging and discharging operations of the battery cells (10); a connecting element (120) arranged to connect selected of the battery terminals together; a connecting tab (150) with a first section (151) extending from the connecting element, a second section (152) in the concave valley region between one of the pairs of adjacent battery cells, and a curved section (153) joining the first and second sections, the connecting tab further comprising a connection arrangement (154, 155) extending from the second section (152) to the printed circuit board (50) to connect the connecting element (120) to the printed circuit board (50), and wherein the connection arrangement (154, 155) comprises the following: a connecting section (155); and a line section (154) which extends diagonally from the second section (152) to the connecting section (155).

Description

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

[0002] Generally, a secondary battery is rechargeable and dischargeable, unlike a primary battery, which is non-rechargeable. A secondary battery is used as a power source in mobile devices, electric vehicles, hybrid vehicles, electric bicycles, and uninterruptible power supplies. It can be used in the form of a single battery or a battery pack in which multiple batteries are electrically connected as a single unit, depending on the type of external device to which the secondary battery is applied.

[0003] A small mobile device, such as a mobile phone, can be powered by the output and capacity of a single battery, but electric vehicles or hybrid vehicles consume a relatively large amount of electrical energy to operate at high electrical power output for long periods of time, and therefore use a battery pack containing multiple batteries. In addition, the output voltage or current can increase according to the number of batteries included in a module.

[0004] According to one aspect of one or more embodiments, a battery pack is suitable for a compact type device by reducing the space occupied by a connecting tab that provides electrical connection between a battery cell and a circuit board.

[0005] According to another aspect of one or more embodiments, a battery pack to which a low-resistance design is applied has a signal transmission path with a reduced length.

[0006] According to another aspect of one or more embodiments, a battery pack includes improved support strength at a connection tab that provides electrical connection between a battery cell and a circuit board.

[0007] Additional aspects will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the presented embodiments.

[0008] According to one or more embodiments, a battery pack includes: at least two battery cells; a circuit board for controlling charging and discharging operations of the battery cells; and a connecting tab electrically connected to the battery cells, extending to the circuit board, including a bent portion proximate the battery cells, and located within a battery location defined by the battery cells.

[0009] The connecting tab may extend from a connecting element that electrically connects adjacent battery cells of the at least two battery cells, and the battery location may be a location that includes a plurality of battery cell regions connected by the connecting element.

[0010] The connecting tab may include: a first portion extending in a first direction from a connecting element that electrically connects adjacent battery cells of the at least two battery cells; and a second portion extending in a length direction of the battery cells over the bent portion, wherein the length direction of the battery cells is different from the first direction.

[0011] The first section of the connecting tab may extend over a valley area between the adjacent battery cells.

[0012] The second section of the connecting tab may be located within a valley area between the adjacent battery cells.

[0013] The connecting element can connect the adjacent battery cells in parallel in the first direction and connect the adjacent battery cells in series in a second direction different from the first direction.

[0014] The connecting tab may further include: a connecting portion connected to the circuit board; and a lead portion extending between the second portion and the connecting portion.

[0015] The connecting tab may include a metal plate formed as a one-piece body.

[0016] The connecting tab may include a metal plate formed integrally with the connecting element.

[0017] The connecting section can be connected directly to the circuit board.

[0018] The circuit board may include a connection hole into which the connection section is inserted.

[0019] The line section may extend diagonally at an oblique angle of inclination to simultaneously follow the first direction and a second direction different from the first direction.

[0020] The circuit board can be located above the battery cells in the first direction.

[0021] The connecting member may include: a first welding portion and a second welding portion relative to the battery cells; and a cutting portion extending between the first welding portion and the second welding portion.

[0022] The battery pack may further include a cell holder configured to receive the battery cells, wherein an inner surface of the cell holder may surround the battery cells, and the circuit board is disposed over an outer surface of the cell holder.

[0023] According to the invention, a battery pack is also provided comprising a plurality of battery cells with battery terminals at opposite ends, wherein the battery cells are arranged side by side in a pack configuration such that a valley is formed between pairs of adjacent battery cells, wherein a circuit board is provided along a side surface of the pack configuration to control charging and discharging operations of the battery cells, wherein a connecting element is arranged at one end of the pack configuration to interconnect selected ones of the battery terminals, wherein a connecting tab has a first portion extending from the connecting element, a second portion in the valley between one of the pairs of adjacent battery cells, and a bent portion joining the first and second portions together, wherein the connecting tab further comprises a connecting arrangement,which extends from the second portion to the circuit board to connect the connecting element to the circuit board.,

[0024] The connecting assembly may include a third portion extending from the second portion to the circuit board and a fourth portion connecting the third portion to the circuit board. The third portion may be arranged to extend diagonally between the second and fourth portions, allowing deflection of the third portion and thus providing some resilient support to the circuit board.

[0025] The batteries can be cylindrical or nearly cylindrical as long as a valley is formed between them when placed side by side.

[0026] The connecting element may be a flat plate. The first portion of the connecting tab may extend in the same plane as that of the flat plate and be bent at a right angle to form the second portion.

[0027] Because the connecting tab extends into the valley between adjacent battery cells, it is protected to a certain extent from damage by the surrounding battery cells.

[0028] These and / or other aspects will become apparent and more easily understood from the following description of one or more embodiments in conjunction with the accompanying drawings, in which: Fig. 1 is a perspective view of a battery pack according to an embodiment, and Fig. 2 is an exploded perspective view of the battery pack of Fig. 1 is; Fig. 3 is a perspective view of a portion of the battery pack of Fig. 1 is; Fig. 4 a perspective view of a connecting tab of the battery pack of Fig. 1; and Fig. 5 a side view of the battery pack of Fig. 1, and Fig. 6 a side view of a portion of the battery pack of Fig. 1 is.

[0029] Referring to the drawings, a battery pack according to one embodiment may include a plurality of battery cells 10, a cell holder 100 for holding the battery cells 10, and a circuit board 50 for controlling charging / discharging operations of the battery cells 10.

[0030] In one embodiment, the battery cell 10 may have different electrodes at opposite ends thereof in a length direction and be formed as a cylinder. A concave valley region "g" may be formed between adjacent battery cells 10, the outer peripheral surfaces of which may be in contact with each other.

[0031] The elongated battery cells 10 can be arranged side by side in a battery pack.

[0032] The plurality of battery cells 10 may include two or more battery cells 10. The plurality of battery cells 10 may be electrically connected to each other in a series manner, a parallel manner, or a combined parallel-serial manner. The plurality of battery cells 10 may be electrically connected to each other via a connecting element 120. For example, the plurality of battery cells 10 may be connected in parallel by the connecting element 120, which electrically connects the same polarities of the adjacent battery cells 10, or may be connected in series by the connecting element 120, which electrically connects opposite polarities of the adjacent battery cells 10.

[0033] For example, an interconnecting element 120 may electrically connect four battery cells 10 together, and the interconnecting element 120 may connect the adjacent battery cells 10 in parallel in a first direction (e.g., a Z1 direction) while connecting the adjacent battery cells 10 in series in a second direction (e.g., a Z2 direction). In one embodiment, the interconnecting element 120 may connect the same polarities of the battery cells 10 that constitute a pair in the first direction (e.g., the Z1 direction) to connect the corresponding battery cells 10 in parallel, and may connect opposite polarities of the battery cells 10 that constitute a pair in the second direction (e.g., the Z2 direction) to connect the corresponding battery cells 10 in series.

[0034] By connecting the battery cells 10 in parallel in the first direction (e.g., the Z1 direction) and connecting the battery cells 10 in series in the second direction (e.g., the Z2 direction), a combined connection of the parallel-serial connections can be obtained. Accordingly, an output capacity of the battery pack can be increased or optimized to be high capacity and high output. In one embodiment, the battery cells 10 can be connected in parallel in the first direction (e.g., the Z1 direction) and can be connected in series in the second direction (e.g., the Z2 direction) by using a connecting element 120, and thus the number of connecting elements 120 for connecting the adjacent battery cells 10 can be reduced.

[0035] The battery cells 10 can be accommodated in the cell holder 100. The cell holder 100 can provide a receiving space having a shape that matches or corresponds to that of the battery cells 10. For example, the cell holder 100 can include a plurality of cylindrical receiving spaces arranged in the first and second directions (e.g., the Z1 and Z2 directions). The cell holder 100 has an inner surface 102 facing the battery cells 10 to surround the battery cells 10 and an outer surface 101 to support the circuit board 50.

[0036] The cell holder 100 can have any of various shapes, provided that the receiving space for the battery cells 10 is provided. For example, the cell holder 100 can be formed as a single body or can be formed by combining different elements. In one embodiment, for example, two different elements arranged between the battery cells 10 and the circuit board 50 can be coupled together to form the cell holder 100. Here, the outer surface 101 of the cell holder 100 can represent a support surface that supports the circuit board 50.

[0037] The battery pack may further include the circuit board 50 for controlling charging / discharging operations of the battery cells 10. The circuit board 50 receives status information of the battery cells 10 and can control the charging / discharging operations of the battery cells 10 based on the status information. For example, the circuit board 50 can receive status information such as a temperature and a voltage of each battery cell 10 and can detect incorrect operations such as overcharging, overdischarging, and overheating based on the status information to take protective measures such as suspending the charging / discharging operations of the battery cell 10. The circuit board 50 can be arranged on the outer surface 101 of the cell holder 100. The circuit board 50 can receive the status information from the battery cells 10 and can be connected to the battery cells 10 via a connection tab 150.

[0038] The connecting tab 150 may include a first portion 151 extending upward toward the outer surface 101 of the cell holder 100 from the connecting element 120, and a second portion 152 disposed on the outer surface 101 of the cell holder 100, and may further include a bent portion 153 connecting the first and second portions 151 and 152. The first portion 151 may extend from the connecting element 120 in the first direction (e.g., the Z1 direction). For example, the first portion 151 may extend from the connecting element 120 over the valley region "g" between the adjacent battery cells 10.

[0039] In one embodiment, the battery cell 10 may have a cylindrical shape and is the concave valley region "g" between the adjacent battery cells 10. Here, the first portion 151 may extend over the valley region "g" between the adjacent battery cells 10 to reduce a spatial height occupied by the connecting tab 150.

[0040] The second portion 152 may extend from the first portion 151 in a direction different from the first direction 151, for example, in a length direction of the battery cell 10, via the bent portion 153. When the first portion 151 extends beyond the valley region "g" between the adjacent battery cells 10, the second portion 152 may be located within the valley region "g." As described above, since the second portion 152 is located within the valley region "g" between the adjacent battery cells 10, fluctuation of the connecting tab 150 with respect to external vibrations or shocks can be prevented or substantially prevented, and the connecting tab 150 can be protected.

[0041] The bent portion 153 of the connecting tab 150 can be arranged within a battery location S. Here, the battery location S can denote an area occupied by a group of battery cells 10 that are electrically connected to one another. For example, the battery location S can denote a square area in the first and second directions (e.g., the Z1 and Z2 directions) that includes an area of ​​the battery cells 10 that are electrically connected to one another via the connecting element 120. Here, for example, the connecting element 120 could electrically connect four different battery cells 10 in a 2 x 2 arrangement. In another embodiment, the battery location S can denote a rectangular area in the first and second directions Z1 and Z2 that includes an area of ​​the battery cells 10 that are electrically connected to one another via the connecting element 120.Here, for example, the interconnection element 120 could electrically connect 6 different battery cells 10 in a 3 x 2 arrangement. In another embodiment, the battery location S may denote a parallelogram including a region of the battery cells 10 that are electrically connected to one another via the interconnection element 120. Here, for example, the interconnection element 120 could electrically connect battery cell stacks in a stacked manner in a 2 x 2 arrangement. In another embodiment, the battery location S may denote a trapezoid including a region of the battery cells 10 that are electrically connected to one another via the interconnection element 120. Here, for example, the interconnection element 120 could electrically connect a battery cell stack in a stacked manner with 2 upper battery cells and 3 lower battery cells.

[0042] When the bent portion 153 of the connecting tab 150 is disposed within the battery location S, the first portion 151 may extend in front of the bent portion 153 over the valley region "g" between the adjacent battery cells 10, and the second portion 152 may be located behind the bent portion 153 within the valley region "g" between the adjacent battery cells 10. This will be described in more detail later.

[0043] In one embodiment, the connecting tab 150 may be directly connected to the circuit board 50. Here, the fact that the connecting tab 150 is directly connected to the circuit board 50 means that no additional connecting element, e.g., a flexible wire, is arranged between the connecting tab 150 and the circuit board 50 to facilitate the electrical connection.

[0044] In one embodiment, the connecting tab 150 may further include a connecting portion 155 that is directly connected to the circuit board 50. The connecting portion 155 may be inserted into a connection hole 50' of the circuit board 50 and may be attached to a connection pad (not shown) around the connection hole 50' by soldering.

[0045] The connection tab 150 may further include a conductive portion 154 extending between the connection portion 155 and the second portion 152. The conductive portion 154 may extend from the second portion 152 to the connection hole 50' of the circuit board 50. A direction in which the conductive portion 154 extends may be any of various directions depending on a configuration of the circuit board 50, such as according to a location of the connection hole 50' of the circuit board 50. In one embodiment, the conductive portion 154 may extend to the connection hole 50' along a lateral direction of the circuit board 50.

[0046] In one embodiment, the lead portion 154 may extend along the second direction (e.g., the Z2 direction) to the connection hole 50' of the circuit board 50 disposed above the battery cells 10. That is, the lead portion 154 may extend along a lateral direction of the circuit board 50 and simultaneously extend upward toward the circuit board 50 to have a diagonal line shape with an inclination angle.

[0047] For example, in one embodiment, the circuit board 50 may be formed having a rectangular shape including a pair of long side portions extending in the second direction (e.g., the Z2 direction) along a direction in which the battery cells 10 are arranged, and a pair of short side portions between the pair of longer side portions. Here, the lead portion 154 may extend at an oblique inclination angle that follows the direction of the long side portion (e.g., the second direction) and the upward direction (e.g., the first direction).

[0048] The battery cell 10 may be electrically connected to adjacent battery cells 10 via the interconnection element 120. In one embodiment, for example, the interconnection element 120 may electrically connect four battery cells 10 to each other, and the interconnection element 120 may connect the adjacent battery cells 10 in parallel in the first direction (e.g., a Z1 direction) while connecting the adjacent battery cells 10 in series in the second direction (e.g., a Z2 direction). In one embodiment, the interconnection element 120 may connect the same polarities of the battery cells 10 that constitute a pair in the first direction (e.g., the Z1 direction) to connect the corresponding battery cells 10 in parallel, and may connect opposite polarities of the battery cells 10 that constitute a pair in the second direction (e.g., the Z2 direction) to connect the corresponding battery cells 10 in series.

[0049] By connecting the battery cells 10 in parallel in the first direction (e.g., the Z1 direction) and connecting the battery cells 10 in series in the second direction (e.g., the Z2 direction), a combined connection of the parallel-serial connections can be obtained. Accordingly, an output capacity of the battery pack can be increased or optimized to be high capacity and high output. In one embodiment, the battery cells 10 can be connected in parallel in the first direction (e.g., the Z1 direction) and can be connected in series in the second direction (e.g., the Z2 direction) by using a connecting element 120, and thus the number of connecting elements 120 for connecting the adjacent battery cells 10 can be reduced.

[0050] In one embodiment, the first portion 151 of the connecting tab 150 may extend in the first direction (e.g., the Z1 direction), which is the parallel connection direction. The first portion 151 of the connecting tab 150 may extend in one of the parallel connection direction and the serial connection direction, excluding the other. This means that according to one embodiment, since the first portion 151 of the connecting tab 150 extends in the first direction (e.g., the Z1 direction), which is the parallel connection direction, the first portion 151 does not extend in the second direction (e.g., the Z2 direction), which is the serial connection direction.

[0051] Since the connecting element 120 performs the serial connection and the parallel connection simultaneously, the output capacity of the battery pack can be increased or optimized at high output and high capacity. In addition, the serial connection and the parallel connection can be performed simultaneously by using one connecting element 120 to reduce the number of connecting elements 120. As described above, the mutually exclusive parallel connection direction and the serial connection direction can be defined with respect to one connecting element 120, and thus the extension direction of the first portion 151 of the connecting tab 150 can be set as an exclusive direction of the parallel connection direction and the serial connection direction.

[0052] The lead portion 154 of the connecting tab 150 may extend in a diagonal direction that simultaneously follows the first direction (e.g., the Z1 direction), which is the parallel connection direction, and the second direction (e.g., the Z2 direction), which is the serial connection direction. The lead portion 154 of the connecting tab 150 extends to the connection hole 50' of the circuit board 50. Since, as described above, the parallel connection direction and the serial connection direction are defined exclusively with respect to a connecting element 120, the extension direction of the lead portion 154 of the connecting tab 150 may be set as the diagonal direction that is between or oblique to each of the parallel connection direction and the serial connection direction.

[0053] The circuit board 50 can form a circuit section for controlling the charging / discharging operations of the battery cells 10. The circuit board 50 can receive status information of the battery cell 10, such as a voltage or a temperature of the battery cell 10, through the connecting tab 150. In addition, the circuit board 50 can control the charging / discharging operations of the battery cell 10 based on the status information of the battery cell 10. The connecting tab 150 is electrically and thermally connected to the battery cell 10 to share the voltage or temperature information of the battery cell 10, and thus the circuit board 50 can receive the status information of the battery cell 10 through the connecting tab 150.

[0054] The circuit board 50 includes the connection hole 50' for connecting to the connection tab 150. Although not shown in the drawings, a connection pad (not shown) may be provided around the connection hole 50', and the status information transmitted through the connection tab 150 may be transmitted to a requesting part of the circuit board 50. In one embodiment, the connection portion 155 of the connection tab 150 may be directly inserted into the connection hole 50' of the circuit board 50. Also, in one embodiment, the connection portion 155 of the connection tab 150 and the connection pad (not shown) may be attached to each other via soldering.

[0055] The circuit board 50 may be supported by the connecting tab 150. In one embodiment, for example, the circuit board 50 is attached to the outer surface 101 of the cell holder 100 and may be supported by the connecting tab 150 extending over the outer surface 101 of the cell holder 100. For example, a plurality of connecting tabs 150 may extend over the outer surface 101 of the cell holder 100, and the circuit board 50 may be firmly positioned on the outer surface 101 of the cell holder 100 via the connecting tabs 150, which are firmly inserted into mutually different connection holes 50'. Here, shocks or vibrations applied to the circuit board 50 can be reduced by elastic support of the connecting tabs 150, and the circuit board 50 can be elastically supported by the lead portion 154 extending diagonally in each of the connecting tabs 150.

[0056] In one embodiment, the interconnecting elements 120 may be arranged in alternating patterns at front and rear portions of the battery pack. For example, in one embodiment, one of the interconnecting elements 120 arranged at a front portion of the battery pack connects third and fourth battery cells 10 to each other in the second direction (e.g., the Z2 direction), and one of the interconnecting elements 120 arranged at a rear portion of the battery pack may not connect the third and fourth battery cells 10, but may connect the second and third battery cells 10 to each other. Thus, the plurality of battery cells 10 may be connected in series by arranging the interconnecting elements 120 alternating at the front and rear portions of the battery pack.

[0057] In one embodiment, the battery cells 10 in a first row and a second row are connected in parallel along the first direction (e.g., the Z1 direction), which is the parallel connection direction, and adjacent battery cells 10 along the second direction (e.g., the Z2 direction) may be connected in series because the connecting tabs 120 are arranged alternately with each other along the second direction (e.g., the Z2 direction), which is the serial connection direction.

[0058] The connecting tab 150 may extend from the connecting element 120 and, in one embodiment, may be formed integrally with the connecting element 120. For example, the connecting tab 150 may include a metal plate formed integrally with the connecting element 120. The connecting tab 150 may transmit voltage information of the battery cell 120 to the circuit board 50. For example, the circuit board 50 may perform an equalization operation based on the voltage information of the battery cell 10 transmitted through the connecting tab 150. The connecting tab 150 may have a narrow or minimal width, provided that the voltage information of the battery cell 10 can be transmitted and such that the width of the connecting tab 150 cannot break due to Joule heat. For example, in one embodiment, the connecting tab 150 may have a width of 2 mm.

[0059] The connecting tab 150 may include the first portion 151 extending from the connecting element 120 to the outer surface 101 of the cell holder 100 in the first direction (e.g., the Z1 direction), and the second portion 152 extending from the first portion 151 to be disposed on the outer surface 101 of the cell holder 100. Additionally, the connecting tab 150 may include the bent portion 153, which changes the direction between the first and second portions 151 and 152.

[0060] The bent portion 153 denotes a bent portion of the connecting tab 150. For example, when the connecting tab 150 has a plurality of bent portions, the bent portion 153 may correspond to a bent portion closest to the battery cell 10. As described later, the bent portion 153 may be located in the battery location S.

[0061] With reference to Fig. 5 and Fig. 6, the bent portion 153 of the connecting tab 150 may be disposed within the battery location S. Here, the battery location S may denote an area occupied by a group of battery cells 10 that are electrically connected to each other. In one embodiment, the battery location S may correspond to a square location that includes locations from the plurality of battery cells 10 that are connected by one of the connecting elements 120 in the first and second directions (e.g., the Z1 and Z2 directions).

[0062] In one embodiment, the bent portion 153 of the connecting tab 150 disposed inside the battery site S denotes that the bent portion 153 of the connecting tab 150 is disposed inside the battery site S without protruding from the battery site S, and as a result, the battery pack of a compact type can be manufactured.

[0063] Alternatively, the first, second and bent portions 151, 152, 153 of the connecting tab (150) lie within the area or envelope S defined by imaginary planes lying along and touching the outermost side surfaces of the adjacent battery cells, such as in Fig. 5, so that the first, second, and bent sections do not extend outside the shell and are protected to a certain extent by the surrounding battery cells. The battery pack can also be made more compact by using the space between the battery cells to connect to the circuit board.

[0064] The connecting tab 150 protrudes upward from the connecting element 120 in the first direction (e.g., the Z1 direction) to extend over the outer surface 101 of the cell holder 100. Here, the connecting tab 150 may protrude upward toward the outer surface 101 up to the bent portion 153 (corresponding to the first portion 151) and may extend parallel to the outer surface 101 of the cell holder 100 past the bent portion 153 (corresponding to the second portion 152). The bent portion 153 of the connecting tab 150 can provide criteria regarding a spatial height occupied by the connecting tab 150, and if the bent portion 153 were located outside the battery location S, the spatial height occupied by the connecting tab 150 would be increased and then a dead space would be increased and not suitable for the compact structure.

[0065] The bent portion 153 of the connecting tab 150 may be disposed within the battery site S. In one embodiment, the connecting tab 150 (particularly, the first portion 151 of the connecting tab 150) may extend beyond the valley region "g" between the adjacent battery cells 10, and the bent portion 153 of the connecting tab 150 may be provided at a height that is the same as or lower than that of a peak point PE of the surface (e.g., the cylindrical surface) of the battery cell. That is, since the connecting tab 150 (particularly, the first portion 151 of the connecting tab 150) extends beyond the valley region "g" of the adjacent battery cells 10, the bent portion 153 of the connecting tab 150 may be formed at a low height where the bent portion 153 does not protrude beyond the peak point PE of the surface (e.g., the cylindrical surface) of the battery cell 10.

[0066] The bent portion 153 of the connecting tab 150, which is arranged within the battery location S, denotes that the first portion 151 of the connecting tab 150 is relatively short, thus a signal transmission path of the connecting tab 150 is reduced to provide a low-resistance design, and thus the status information of the battery cell 10 can be transmitted with high accuracy.

[0067] When the first portion 151 of the connecting tab 150 extends across the valley region "g" between the adjacent battery cells 10, the second portion 152 of the connecting tab 150 can be disposed behind the bent portion 153 within the valley region "g" between the adjacent battery cells 10. When the connecting tab 150 is disposed in the valley region "g" between the adjacent cells 10, the connecting tab 150 can be firmly positioned. This means that the connecting tab 150 does not interfere with other components in the valley region "g" and can be firmly supported even when subjected to external shocks or vibrations.

[0068] With reference to Fig.6, in one embodiment, the connecting member 120 may be coupled to the battery cells 10 via welding. For example, the connecting member 120 may include first and second welding portions P1 and P2 corresponding to each battery cell 10, and a cut portion C extending between the first and second welding portions P1 and P2. Although not shown in the drawings, the connecting member 120 and the battery cell 10 may be welded together by a welding current applied by two welding electrodes (not shown) with different polarities, and then the first and second welding portions P1 and P2, which are different from each other, may be formed in the connecting member 120. Here, the cut portion C may be formed between the first and second welding portions P1 and P2. The cut portion C may prevent or substantially prevent leakage current, e.g., from occurring.the welding current applied to the first and second welding portions P1 and P2 flows along the surface of the connecting member 120, not along bonded surfaces between the connecting member 120 and the battery cell 10. The cutting portion C increases a path connection between the first and second welding portions P1 and P2 to prevent or substantially prevent the first and second welding portions P1 and P2 from being directly bonded to each other via the surface of the connecting member 120.

[0069] According to one or more embodiments, the space occupied by the connecting tab, which provides electrical connection between the battery cells and the circuit board, can be reduced to form a compact battery pack structure. Additionally, the signal transmission path through the connecting tab is reduced to provide the low-resistance structure. The space occupied by the connecting tab can be reduced by utilizing the valley area between adjacent battery cells. At the same time, the connecting tab is arranged in the valley area so as not to interfere with other components, and the connecting tab can be firmly supported even when external shocks or vibrations are applied to the battery pack.

[0070] It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered available to other similar features or aspects in other embodiments.

[0071] Although one or more embodiments have been described with reference to the drawings, it will be understood by one of ordinary skill in the art that various changes in form and details may be made therein without departing from the scope of the invention as defined by the following claims.

Claims

[1] Battery pack comprising: a plurality of cylindrical battery cells (10) having battery terminals at opposite ends thereof, the battery cells arranged side by side in a pack configuration such that a concave valley region is formed between pairs of adjacent battery cells; a circuit board (50) provided along a side surface of the pack configuration to control charging and discharging operations of the battery cells (10); a connecting element (120) arranged to interconnect selected ones of the battery terminals; a connecting tab (150) having a first portion (151) extending from the connecting element, a second portion (152) in the concave valley region between one of the pairs of adjacent battery cells, and a bent portion (153) joining the first and second portions, the connecting tab further comprising a connecting arrangement (154, 155) extending from the second portion (152) to the circuit board (50) to connect the connecting element (120) to the circuit board (50), and wherein the connecting arrangement (154, 155) comprises: a connecting section (155); and a line section (154) extending diagonally from the second section (152) to the connecting section (155). [2] The battery pack according to claim 1, wherein the first portion (151) extends in a first direction from the connecting member (120); and the second portion (152) extends in a length direction of the battery cells over the bent portion, the length direction of the battery cells being different from the first direction. [3] The battery pack of claim 2, wherein the first portion of the connecting tab extends over the concave valley region between the adjacent battery cells. [4] The battery pack according to claim 2 or 3, wherein the connecting member (120) connects the adjacent battery cells in parallel in the first direction and connects the adjacent battery cells in series in a second direction different from the first direction. [5] The battery pack according to claim 1, wherein the connecting portion is directly connected to the circuit board. [6] The battery pack according to claim 5, wherein the circuit board includes a connection hole (50') into which the connection portion is inserted. [7] The battery pack of claim 1, wherein the circuit board is located above the battery cells in the first direction. [8] Battery pack according to one of the preceding claims, wherein the connecting element (120) comprises: a first welding section and a second welding section with respect to the battery cells; and a cutting section extending between the first welding section and the second welding section. [9] A battery pack according to any one of the preceding claims, further comprising a cell holder (100) configured to receive the battery cells, wherein an inner surface of the cell holder surrounds the battery cells and the circuit board is disposed over an outer surface of the cell holder.

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