Battery assembly
Patent Information
- Application Number
- KR1020250015706
- Authority / Receiving Office
- KR · KR
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-02-07
- Publication Date
- 2026-08-14
Smart Images
Figure P1020250015706_ABST
Abstract
Description
Technology Field
[0001] The present disclosure relates to a battery assembly. Background Technology
[0002] The operating principle of a lithium-ion battery is an electrochemical oxidation-reduction reaction. In other words, it is a principle in which electricity is generated through the movement of lithium ions, and charging occurs through the reverse process. In the case of a lithium-ion battery, the phenomenon in which lithium ions from the anode move to the cathode through the electrolyte and separator is called discharge. The reverse process of this phenomenon is called charging.
[0003] However, due to recent fires and explosions involving lithium-ion batteries, social concerns regarding battery safety are rising. One of the major development challenges for lithium-ion batteries recently is to eliminate the instability associated with battery use, such as fires and / or explosions caused by thermal propagation and thermal runaway in battery cells.
[0004] Therefore, there is a need for measures to secure space for heat dissipation of the battery itself and for the effective exhaust of gases generated inside the battery. The problem to be solved
[0005] According to one aspect of the present disclosure, the problem is to improve the stability of a battery assembly.
[0006] According to another aspect of the present disclosure, the problem is to delay thermal runaway generated inside a battery assembly.
[0007] According to another aspect of the present disclosure, the problem is to improve the lifespan of a battery assembly.
[0008] According to another aspect of the present disclosure, the problem is to improve the space utilization of a battery assembly.
[0009] Meanwhile, the battery assembly according to the present disclosure can be widely applied in green technology fields such as electric vehicles, battery charging stations, energy storage systems (ESS), and other photovoltaic and wind power generation that utilize battery cells. In addition, the battery assembly according to the present disclosure can be used in eco-friendly mobility, including electric vehicles and hybrid vehicles, to prevent climate change by suppressing air pollution and greenhouse fluid emissions. means of solving the problem
[0010] A battery assembly according to the present disclosure may include: a receiving case forming a receiving space inside; a plurality of battery cells arranged along a predetermined stacking direction in the receiving space, each cell case and an electrode assembly arranged in the cell case, and a lead tab portion electrically connected to the electrode assembly and protruding to the outside of the cell case; wherein the plurality of battery cells includes a first group of battery cells arranged with the lead tab portion protruding to one side of the cell case and a second group of battery cells arranged with the lead tab portion protruding to the other side of the cell case, which are alternately arranged along the stacking direction; a first exhaust passage formed between the receiving case and the receiving space facing the lead tab portion of the first group of battery cells; and a second exhaust passage formed between the receiving case and the receiving space facing the lead tab portion of the second group of battery cells.
[0011] A battery assembly according to the present disclosure may further include cooling plates disposed respectively on one side of the first group of battery cells, between the first group of battery cells and the second group of battery cells, and on the other side of the second group of battery cells.
[0012] A battery assembly according to the present disclosure may further include a first bus bar connecting a cooling plate disposed on one side of a first group of battery cells and a lead tab portion of the first group of battery cells, and a second bus bar connecting a cooling plate disposed between the first group of battery cells and a second group of battery cells and a lead tab portion of the second group of battery cells.
[0013] In one embodiment, the cooling plate disposed on one side of the first bus bar and the first group of battery cells, and the cooling plate disposed between the second bus bar and the first group of battery cells and the second group of battery cells can each be welded together.
[0014] In one embodiment, an insulating member may be attached to each of the first busbar and the second busbar.
[0015] In one embodiment, the insulating member may include any one of mica, glass fiber, and ceramic fiber, or a combination thereof.
[0016] In one embodiment, the first group of battery cells may form a first vent hole to allow gas generated inside the first group of battery cells to be discharged.
[0017] In one embodiment, a first insulating sheet may be attached to the surface of the cell case of the first group of battery cells in which the first vent hole is formed.
[0018] In one embodiment, the first insulating sheet may have a slit formed at a position corresponding to the first vent hole so that gas discharged from the first vent hole is discharged to the outside.
[0019] In one embodiment, the battery cell of the second group may form a second vent hole so that gas generated inside the battery cell of the second group is discharged.
[0020] In one embodiment, a second insulating sheet may be attached to the surface of the cell case of the second group of battery cells having a second vent hole formed therein.
[0021] In one embodiment, the second insulation sheet may have a slit formed at a position corresponding to the second vent hole so that gas discharged from the second vent hole is discharged to the outside.
[0022] In one embodiment, each of the first group of battery cells and the second group of battery cells includes a plurality of battery cells, and may further include a plate-shaped first protective member disposed between the plurality of battery cells included in the first group of battery cells; and a plate-shaped second protective member disposed between the plurality of battery cells included in the second group of battery cells. Effects of the invention
[0023] According to one embodiment of the present disclosure, the stability of the battery assembly can be improved.
[0024] According to another embodiment of the present disclosure, thermal runaway generated inside a battery assembly can be delayed.
[0025] According to another embodiment of the present disclosure, the life of the battery assembly can be improved.
[0026] According to another embodiment of the present disclosure, the space utilization of the battery assembly can be improved. Brief explanation of the drawing
[0027] FIG. 1a is an exploded view of a battery assembly according to the present disclosure. FIG. 1b illustrates a battery assembly according to the present disclosure. FIG. 1c illustrates a battery assembly according to the present disclosure. FIG. 1d illustrates the exhaust path of a battery assembly according to the present disclosure. FIG. 2a illustrates a battery assembly according to the present disclosure. FIG. 2b illustrates a battery assembly according to the present disclosure. FIG. 3 illustrates a battery assembly according to the present disclosure as viewed from one direction. FIG. 4 illustrates a battery assembly according to the present disclosure. FIGS. 5A, FIGS. 5B, FIGS. 6, and FIGS. 7 illustrate a battery assembly according to the present disclosure as viewed from one direction. FIG. 8 illustrates a battery assembly according to the present disclosure. FIG. 9 illustrates a first cooling channel and a cooling plate according to the present disclosure. FIG. 10 illustrates a second cooling channel and a cooling plate according to the present disclosure. Specific details for implementing the invention
[0028] Specific terms used in this specification are for convenience of explanation only and are not intended to limit the exemplified embodiments.
[0029] For example, expressions such as "identical" and "to be identical" indicate not only a strictly identical state, but also a state where tolerances or differences exist in the degree to which the same function is obtained.
[0030] For example, expressions indicating relative or absolute arrangements such as “in a certain direction,” “along a certain direction,” “parallel,” “perpendicular,” “to the center,” “concentric,” or “coaxial” not only strictly indicate such arrangements, but also indicate a state of relative displacement with a tolerance or an angle or distance such that the same function is obtained.
[0031] The use of terms such as 'first, second, third' preceding the components mentioned below is intended solely to avoid confusion regarding the components being referred to, and is unrelated to the order, importance, or master-subordinate relationship between the components. For example, an invention including only the second component without the first component can be implemented.
[0032] Singular expressions used in this specification may include plural expressions unless the context clearly indicates otherwise.
[0033] Preferred embodiments of the present disclosure are described in detail below with reference to the attached drawings. The configuration of the device or the control method described below are intended only to explain the embodiments of the present disclosure and are not intended to limit the scope of the rights of the present disclosure, and reference numerals used identically throughout the specification indicate identical components.
[0034] FIG. 1a is an exploded view of a battery assembly according to the present disclosure. FIG. 1b illustrates a battery assembly according to the present disclosure.
[0035] More specifically, FIG. 1a shows an exploded view of the battery assembly (100) shown in FIG. 1b.
[0036] Referring to FIG. 1a, a battery assembly (100) according to the present disclosure may include a plurality of battery cells (200). A battery assembly (100) according to the present disclosure may represent a battery module including a plurality of battery cells (200).
[0037] Each of the plurality of battery cells (200) according to the present disclosure may be a secondary battery capable of repeatedly performing charging and discharging. In one embodiment, each of the plurality of battery cells (200) may be a secondary battery of various types, such as a lithium-ion battery, a vanadium-ion battery, an all-solid-state battery, a metal-air battery, a sodium-ion battery, or an aluminum-ion battery.
[0038] Each of the plurality of battery cells (200) can be stacked and arranged in a predetermined first direction (X-axis direction) and second direction (Y-axis direction). Each of the plurality of battery cells (200) can represent a prismatic battery cell.
[0039] A battery assembly (100) according to the present disclosure may include a receiving case comprising an upper case (104a) disposed above a plurality of battery cells (200) and a lower case (104b) disposed below a plurality of battery cells (200). The upper case (104a) and the lower case (104b) may serve to form an exhaust path for discharging gas or heat discharged from inside the plurality of battery cells (200) through a vent hole formed in each of the plurality of battery cells (200). Each of the plurality of battery cells (200) according to the present disclosure may include a vent hole (610, 630 in FIG. 6) for discharging heat or gas inside the plurality of battery cells (200). The upper case (104a) and the lower case (104b) may serve to prevent gas or heat from propagating to adjacent battery cells among the plurality of battery cells (200) when gas or heat is discharged. Additionally, the upper case (104a) and the lower case (104b) may serve to fix the position of a plurality of battery cells (200) inside the battery assembly (100) or to protect the plurality of battery cells (200) from impact. According to one embodiment, the upper case (104a) and the lower case (104b) may be formed of a metal, ceramic, or polymer material. For example, the metal may include steel, but the type of metal may not be limited thereto.
[0040] The receiving case according to the present disclosure may further include a side case (101). The side case (101) may be combined with an upper case (104a) and a lower case (104b).
[0041] In one embodiment, the upper case (104a) and the lower case (104b) may be spaced apart in the height direction. The height direction may represent a third direction (Z-axis direction). The first direction (X-axis direction), the second direction (Y-axis direction), and the third direction (Z-axis direction) may represent directions perpendicular to each other.
[0042] The upper case (104a), lower case (104b), and side case (101) can be combined with each other to form a receiving space for a plurality of battery cells (100). A plurality of battery cells (200) can be received in the receiving space.
[0043] In one embodiment, each of the plurality of battery cells (200) may include a cell case including an electrode assembly and a lead tab portion (202a, 202b in FIG. 2A) electrically connected to the electrode assembly and protruding to one side of the cell case. That is, each of the plurality of battery cells (200) may include a unidirectional battery cell in which the lead tab portion (202a, 202b) protrudes to one side. In one embodiment, the plurality of battery cells (200) may include a first group of battery cells (501 in FIG. 2A) in which the lead tab portion (202a, 202b) is arranged to face the upper case (104a) and a second group of battery cells (502 in FIG. 2A) in which the lead tab portion (202a, 202b) is arranged to face the lower case (104b). At this time, the first group of battery cells (501) and the second group of battery cells (502) may be arranged alternately along the first direction (X-axis direction). In one embodiment, the first group of battery cells (501) may form a vent hole (610) in a direction facing the upper case (103a). For example, the second group of battery cells (502) may form a vent hole (630) in a direction facing the lower case (103b).
[0044] The vent hole (610) of the first group of battery cells (501) according to the present disclosure may be formed in a direction facing the lower case (103b). That is, the vent hole (610) may be formed on the surface of the cell case where the lead tab portion included in each of the first group of battery cells (501) is not formed.
[0045] The vent hole (630) of the second group of battery cells (502) according to the present disclosure may be formed in a direction facing the upper case (103a). That is, the vent hole (630) may be formed on the surface of the cell case where the lead tab portion included in each of the second group of battery cells (502) is not formed.
[0046] In one embodiment, each of the first group of battery cells (501) and the second group of battery cells (502) may include a plurality of battery cells in which a predetermined number of battery cells are arranged in each of the first direction (X-axis direction) and the second direction (Y-axis direction). For example, the predetermined number may be set to two, but the number may not be limited thereto. For example, the predetermined number included in the first group of battery cells (501) and the predetermined number included in the second group of battery cells (502) may be set differently from each other.
[0047] A battery assembly (100) according to the present disclosure may further include an insulating sheet (320) attached to a plurality of battery cells (200). The insulating sheet (320) can prevent heat transfer between the plurality of battery cells (200) and the outside and / or heat transfer between adjacent battery cells among the plurality of battery cells (200). For example, the material of the insulating sheet (320) may be formed from any one or a combination of mica, flame retardant materials (FR), fire extinguishing agents, and ceramic wool. However, this is merely an example, and the insulating sheet (320) of the present disclosure may not be limited to the material of the example above as long as it is a material capable of preventing heat transfer.
[0048] An insulating sheet (320) can be attached to the cell case of each of the plurality of battery cells (200). Specifically, the insulating sheet (320) can be attached to the surface where the lead tab portion (202a, 202b) is positioned among the surfaces forming the cell case. The insulating sheet (320) can be attached to the surface where the vent hole is formed among the surfaces forming the cell case of each of the plurality of battery cells (200). For example, the insulating sheet (320) can be attached to the surface of the cell case of the first group of battery cells (501) facing the upper case (104a). The insulating sheet (320) can be attached to the surface of the cell case of the second group of battery cells (502) facing the lower case (104b).
[0049] The insulation sheet (320) may have a slit (320a) formed therein to allow gas or heat emitted from a plurality of battery cells (200) to be discharged to the outside. The slit (320a) may be formed at a location corresponding to the location where the vent hole is formed.
[0050] The battery assembly (100) according to the present disclosure may further include a bus bar (310) to connect the lead tab portions of adjacent battery cells among a plurality of battery cells (200) to each other.
[0051] A battery assembly (100) according to the present disclosure may further include an insulating member (105) disposed on a busbar (310). The insulating member (105) may include an insulating tape. The material of the insulating member (105) may include any one or a combination of mica, flame retardant materials (FR), fire extinguishing agents, glass fibers, and ceramic fibers. However, this is merely an example, and the insulating member (105) of the present disclosure may not be limited to the material of the example above as long as it is a material capable of insulating the busbar (310). The insulating member (105) may serve to insulate the busbar (310) and prevent short circuits. The insulating member (105) may serve to prevent heat transfer between a plurality of battery cells (200).
[0052] A battery assembly (100) according to the present disclosure may further include a cooling plate (110) disposed between a first group of battery cells (501) and a second group of battery cells (502). The cooling plate (110) may be stacked and arranged along a first direction (X-axis direction).
[0053] The cooling plate (110) may be formed of a metal material so that at least some of its area is insulated. The cooling plate (110) may also be formed of a non-metal material including plastic.
[0054] The battery assembly (100) according to the present disclosure may further include a first cooling channel (250a in FIG. 2a) and a second cooling channel (250b in FIG. 2a). Either of the first cooling channel (250a) and the second cooling channel (250b) may be a channel through which a cooling medium (cooling water) flowing into a cooling plate (110) flows, and the other may be a channel through which a cooling medium flowing out of the cooling plate (110) flows.
[0055] The battery assembly (100) according to the present disclosure may further include a support plate (102). The support plate (102) may be referred to as a hose guide. The support plate (102) may be coupled to a side case (101). The support plate (102) may protect a first cooling channel (250a) and a second cooling channel (250b).
[0056] The battery assembly (100) according to the present disclosure may further include a Cell Monitoring Unit (CMU) (not shown). The CMU may measure state information including at least one of the voltage, current, or temperature of a plurality of battery cells (200) and transmit the state information to an external device.
[0057] The battery assembly (100) according to the present disclosure may further include an exhaust passage through which gas or heat output from the vent hole (610, 630 in FIG. 6) is discharged.
[0058] The battery assembly (100) according to the present disclosure may further include a first exhaust passage through which heat or gas discharged from a vent hole (610) of a first group of battery cells (501 in FIG. 2a) is discharged. The first exhaust passage may be formed between an upper case (104a) facing a lead tab portion of a first group of battery cells (501) and a receiving space for a plurality of battery cells (200).
[0059] The battery assembly (100) according to the present disclosure may further include a second exhaust passage through which heat or gas discharged from the vent hole (630) of a second group of battery cells (501 in FIG. 2a) is discharged. The second exhaust passage may be formed between a lower case (104b) facing the lead tab portion of the second group of battery cells (501) and a receiving space for a plurality of battery cells (200).
[0060] According to one embodiment, the upper case (104a) and the lower case (104b) may further include a recess that is recessed along a third direction (Z-axis direction). For example, the upper case (103a) may form a recess that is recessed in a direction away from the receiving space along the third direction (Z-axis direction). For example, the lower case (104b) may form a recess that is recessed in a direction away from the receiving space along a direction symmetric to the third direction (Z-axis direction) (-Z-axis direction).
[0061] That is, the first exhaust passage may be formed in a recess formed by being sunken in a direction away from the receiving space of a plurality of battery cells (200) in the upper case (104a). The second exhaust passage may be formed in a recess formed by being sunken in a direction away from the receiving space of a plurality of battery cells (200) in the lower case (104b).
[0062] In one embodiment, heat or gas generated in the first group of battery cells (501) can be discharged through the vent hole (610) to the slit (320a) formed in the insulation sheet (320). In one embodiment, the heat or gas discharged through the slit (320a) can be discharged to the outside of the battery assembly (100) through the first exhaust path.
[0063] In one embodiment, heat or gas generated in the second group of battery cells (502) can be discharged through the vent hole (630) to the slit (320a) formed in the insulation sheet (320). In one embodiment, the heat or gas discharged through the slit can be discharged to the outside of the battery assembly (100) through the second exhaust path.
[0064] The battery assembly (100) according to the present disclosure may separate the exhaust passages in the vertical direction along the height direction (third direction) of the battery assembly (100) by arranging the first exhaust passage in the direction toward the upper case (104a) and the second exhaust passage in the direction toward the lower case (104b). Through this, the battery assembly (100) has the effect of ensuring the stability of the battery cell (200).
[0065] A battery assembly (100) according to the present disclosure can directly cool the surfaces of a plurality of battery cells (200) in contact with the cooling plate (110) by placing a cooling plate (110) between a first group of battery cells (501) and a second group of battery cells (502).
[0066] The battery assembly (100) according to the present disclosure may not connect the first group of battery cells (501) and the second group of battery cells (502) through a separate connecting member, thereby increasing the space utilization of the battery assembly (100). The battery assembly (100) according to the present disclosure may connect the lead tab portions (202a, 202b) of the first group of battery cells (501) and the lead tab portions (202a, 202b) of the second group of battery cells (502) to each other through a cooling plate (110) disposed between the first group of battery cells (501) and the second group of battery cells (502). That is, the battery assembly (100) according to the present disclosure can increase the space utilization of the battery assembly (100) while serving to cool between the first group of battery cells (501) and the second group of battery cells (502) through the cooling plate (110).
[0067] FIG. 1c illustrates a battery assembly according to the present disclosure.
[0068] Referring to FIG. 1c, a battery assembly (180) according to the present disclosure may represent a battery pack that accommodates at least one battery assembly (100) representing a battery module (e.g., the battery assembly (100) of FIG. 1a and FIG. 1b).
[0069] A battery assembly (180) according to the present disclosure may include a receiving body (213) and a receiving cover (103) forming a receiving space for receiving a battery module (e.g., a battery assembly (100) of FIG. 1a and FIG. 1b).
[0070] In one embodiment, the receiving body (213) may form members (211, 212) that partition the receiving space. The members (211, 212) may include a first member (211) formed along a first direction (X direction) and a second member (212) formed along a second direction (Y direction).
[0071] In one embodiment, the receiving body (213) may be connected to the receiving cover (103). According to one embodiment, the receiving body (213) may be connected to the receiving cover (103) by using an adhesive member. Alternatively, in one embodiment, the receiving body (213) and the receiving cover (103) may be connected to each other by combining a hole formed in one and an insertion part formed in the other. For example, the receiving cover (103) may form a hole, and the receiving body (213) may form an insertion part that can penetrate the hole formed in the receiving cover (103). For example, the receiving body (213) may form a hole, and the receiving cover (103) may form an insertion part that can penetrate the hole formed in the receiving body (213).
[0072] FIG. 1d illustrates the exhaust path of a battery assembly according to the present disclosure.
[0073] More specifically, referring to FIG. 1d, this is a drawing showing a battery assembly (100) placed in a receiving space formed in a receiving body (213).
[0074] In one embodiment, the receiving cover (103) can serve to protect a battery assembly (100) including a plurality of battery cells (200) from impact.
[0075] In one embodiment, the receiving body (213) may have an outlet formed therein so that heat or gas generated in each of the battery assemblies (100) can be discharged to the outside (130).
[0076] According to one embodiment, heat or gas discharged through a first exhaust passage formed in a recess formed in a direction away from the receiving space of a plurality of battery cells (200) in the upper case (104a) can be discharged to the outside of the battery assembly (180) through an exhaust port.
[0077] According to one embodiment, heat or gas discharged through a second exhaust passage formed in a recess formed in a direction away from the receiving space of a plurality of battery cells (200) in the lower case (104b) can be discharged to the outside of the battery assembly (180) through an exhaust port.
[0078] Since each battery assembly (100) is spatially separated from an adjacent battery assembly through a first member (211) and a second member (212), heat or gas generated in the battery assembly (100) may not be transferred to the adjacent battery assembly.
[0079] FIG. 2a illustrates a battery assembly according to the present disclosure.
[0080] Specifically, for convenience of explanation, FIG. 2a is illustrated with some components of the battery assembly (100) of FIG. 1a omitted.
[0081] According to one embodiment, a plurality of battery cells (200) may be stacked along a second direction (Y-axis direction) among a predetermined first direction (X-axis direction) and a direction perpendicular to the first direction.
[0082] Each of the plurality of battery cells (200) may include a cell case including an electrode assembly and a lead tab portion (202a, 202b) electrically connected to the electrode assembly and protruding to one side of the cell case.
[0083] The first lead tab portion (202a) may represent a lead tab portion of a first polarity, and the second lead tab portion (202b) may represent a lead tab portion of a second polarity different from the first polarity. For example, the first polarity may be a positive polarity and the second polarity may be a negative polarity. Alternatively, the first polarity may be a negative polarity and the second polarity may be a positive polarity. A plurality of battery cells (200) may include a first group of battery cells (501) arranged such that the lead tab portions (202a, 202b) face the upper case (103a), and a second group of battery cells (502) arranged such that the lead tab portions (202a, 202b) face the lower case (103b). Each of the first group of battery cells (501) may be arranged so that a vent hole faces the upper case (104a), and each of the second group of battery cells (502) may be arranged so that a vent hole faces the lower case (104b). In one embodiment, a slit (320a) corresponding to the vent hole formed in each of the first group of battery cells (501) may be formed on the insulating sheet (320).
[0084] The first group of battery cells (501) and the second group of battery cells (502) can be alternately arranged along a preset first direction (X-axis direction) in a space for receiving a plurality of battery cells (200).
[0085] In one embodiment, each of the first group of battery cells (501) and the second group of battery cells (502) may include a predetermined number of multiple battery cells. The first group of battery cells (501) may include a predetermined number of battery cells arranged in each of the first direction (X-axis direction) and the second direction (Y-axis direction). The second group of battery cells (502) may include a predetermined number of battery cells arranged in each of the first direction (X-axis direction) and the second direction (Y-axis direction). For example, the predetermined number may be set to two, but the predetermined number may not be limited thereto.
[0086] A plate-shaped protective member (220) may be disposed between a plurality of battery cells included in the first group of battery cells (501). A plate-shaped protective member (220) may be disposed between a plurality of battery cells included in the second group of battery cells (502).
[0087] The protective member (220) can block heat propagation between a plurality of battery cells (200). The protective member (220) may be formed from a material having heat resistance and thermal insulation properties. For example, the protective member (220) may include at least some of the following materials: mica, mica sheet, silicate, lapite, alumina, ceramic wool (or super wool), and aerogel. However, the material of the protective member (220) of the present disclosure is not limited thereto, and may be formed from various materials as long as it can maintain its shape in a thermal runaway situation between a plurality of battery cells (200) and prevent delaying thermal runaway.
[0088] The cooling plates (110) can be stacked and arranged along a predetermined first direction (X-axis direction). The cooling plates (110) can be extended and formed along a second direction (Y-direction).
[0089] In one embodiment, the cooling plate (110) may be disposed on one side of the first group of battery cells (501). The cooling plate (110) may be in contact with one side of the first group of battery cells (501) to cool one side of the first group of battery cells (501).
[0090] In one embodiment, the cooling plate (110) may be placed between a first group of battery cells (501) (e.g., the other side of the first group of battery cells (501)) and a second group of battery cells (502) (e.g., one side of the second group of battery cells (502). The cooling plate (110) may be in contact with the first group of battery cells (501) and the second group of battery cells (502) to cool the first group of battery cells (501) and the second group of battery cells (502).
[0091] In one embodiment, the cooling plate (110) may be placed on the other side of the second group of battery cells (502). The cooling plate (110) may be in contact with the other side of the second group of battery cells (502) to cool the other side of the second group of battery cells (502).
[0092] The battery assembly (100) according to the present disclosure may further include a first cooling channel (250a) and a second cooling channel (250b). A cooling medium (cooling water) may flow through the first cooling channel (250a) and the second cooling channel (250b).
[0093] The first cooling channel (250a) and the second cooling channel (250b) may be connected to one end of the cooling plate (110). The cooling plate (110) may include an open area that can be opened and closed. The cooling plate (110) may allow a cooling medium to flow into or out of the cooling plate (110) through the open area. The cooling plate (110) may close the open area to prevent the cooling medium from flowing out.
[0094] The first cooling channel (250a) and the second cooling channel (250b) can be formed by extending along a preset first direction (X-axis direction).
[0095] The first cooling channel (250a) can move the cooling medium along a predetermined first direction (X-axis direction). The first cooling channel (250a) can introduce the cooling medium moving along the predetermined first direction (X-axis direction) into a cooling plate (110) formed to extend in a second direction (Y-axis direction). At this time, the open area of the cooling plate (110) may be in an open state.
[0096] The cooling medium, whose temperature has risen by cooling a plurality of battery cells (200) through the cooling plate (110), can flow out to the second cooling channel (250b) through the open area of the cooling plate (110). The second cooling channel (250b) can move the cooling medium along a predetermined first direction (X-axis direction).
[0097] In one embodiment, the battery assembly (100) according to the present disclosure may include a first terminal portion (211) and a second terminal portion (212). The first terminal portion (211) and the second terminal portion (212) may represent terminals that can be electrically connected between the battery assembly (100) and an external device. Either one of the first terminal portion (211) and the second terminal portion (212) may represent a positive terminal and the other may represent a negative terminal. The positive terminal may be referred to as HV (high voltage) positive, and the negative terminal may be referred to as HV (high voltage) negative.
[0098] In one embodiment, a Cell Monitoring Unit (CMU) (not shown) may be disposed between the first terminal section (211) and the second terminal section (212). In one embodiment, the location where the Cell Monitoring Unit (CMU) (not shown) is disposed may not be limited to between the first terminal section (211) and the second terminal section (212). The CMU may measure state information including at least one of the voltage, current, or temperature of a plurality of battery cells (200) and transmit the state information to an external device.
[0099] FIG. 2b illustrates a battery assembly according to the present disclosure.
[0100] More specifically, FIG. 2b is a drawing illustrating an embodiment in which the first group of battery cells (501) of FIG. 2a and the second group of battery cells (502) of FIG. 2a each may include one battery cell instead of including two battery cells in each of the first direction (X-axis direction) and the second direction (Y-axis direction). For example, the first group of battery cells (501) may include a plurality of battery cells in which a predetermined number of battery cells are arranged along each of the first direction (X-axis direction) and the second direction (Y-axis direction). The second group of battery cells (502) may include a plurality of battery cells in which a predetermined number of battery cells are arranged along each of the first direction (X-axis direction) and the second direction (Y-axis direction). However, this is just an example, and the preset number of multiple battery cells included in each of the first group of battery cells (501) and the second group of battery cells (502) of FIG. 2a is not limited to this and can be implemented in various numbers.
[0101] In one embodiment, the description of FIG. 2a may be applied in the same way to FIG. 2b.
[0102] FIG. 3 illustrates a battery assembly according to the present disclosure as viewed from one direction.
[0103] More specifically, FIG. 3 illustrates the battery assembly (100) of FIG. 1a as viewed from the third axis direction (Z-axis direction), and for convenience of explanation, some of the components of the battery assembly (100) have been omitted.
[0104] An insulating sheet (320) can be attached to each cell case of a plurality of battery cells (200).
[0105] For example, an insulating sheet (320) may be attached to the surface of the cell case where a vent hole (610 in FIG. 6) is formed in the first group of battery cells (501). An insulating sheet (320) may not be attached to the surface of the cell case where a vent hole is not formed in the first group of battery cells (501).
[0106] For example, an insulating sheet (320) may be attached to the surface of the cell case where a vent hole is formed in the second group of battery cells (502). An insulating sheet (320) may not be attached to the surface of the cell case where a vent hole (630 in FIG. 6) is not formed in the second group of battery cells (502).
[0107] The insulating sheet (320) attached to the first group of battery cells (501) may form a slit (320a) to allow gas or heat emitted from the first group of battery cells (501) to be discharged to the outside. For example, the shape of the slit may not be limited to the shape shown in FIG. 3 as long as gas or heat can be discharged to the outside.
[0108] The insulating sheet (320) attached to the second group of battery cells (502) can form a slit (320a) to allow gas or heat emitted from the second group of battery cells (502) to be discharged to the outside.
[0109] A slit (320a) can be formed at a position corresponding to the vent hole (610, 630).
[0110] FIG. 4 illustrates a battery assembly according to the present disclosure.
[0111] More specifically, FIG. 4 is illustrated with the omission of a part of the configuration (e.g., insulating member (105)) of the battery assembly (100) of FIG. 1a according to the present disclosure.
[0112] Referring to FIGS. 3 and 4, in one embodiment, a first group of battery cells (501) may include a first battery cell (201), a second battery cell (202) stacked in a first direction (X-axis direction) relative to the first battery cell (201) and positioned adjacent to the first battery cell (201), a third battery cell (203) stacked in a second direction (Y-axis direction) relative to the first battery cell (201) and positioned adjacent to the first battery cell (201), and a fourth battery cell (204) stacked in a first direction (X-axis direction) relative to the third battery cell (203) and positioned adjacent to the third battery cell (203).
[0113] In one embodiment, the first lead tab portion (202a) of the first polarity of the first battery cell (201) and the first lead tab portion (202a) of the first polarity of the second battery cell (202) can be connected to each other through a bus bar (310). That is, adjacent first lead tab portions (202a) of the same first polarity can be connected in parallel through a bus bar (310).
[0114] In one embodiment, the second lead tab portion (202b) of the second polarity of the third battery cell (203) and the second lead tab portion (202b) of the second polarity of the fourth battery cell (204) can be connected to each other through a bus bar (310). That is, adjacent second lead tab portions (202b) of the same second polarity can be connected in parallel through a bus bar (310).
[0115] In one embodiment, the second lead tab portion (202b) of the second polarity of the first battery cell (201) and the first lead tab portion (202a) of the first polarity of the third battery cell (203) can be connected to each other through a bus bar (310). In one embodiment, the second lead tab portion (202b) of the second polarity of the second battery cell (202) and the first lead tab portion (202a) of the first polarity of the fourth battery cell (204) can be connected to each other through a bus bar (310). In one embodiment, the second lead tab portion (202b) of the second polarity of the first battery cell (201) and the second lead tab portion (202b) of the second polarity of the second battery cell (202) can be connected to each other through a bus bar (310). In one embodiment, the second lead tab portion (202b) of the second polarity of the second battery cell (202) and the first lead tab portion (202a) of the first polarity of the fourth battery cell (204) can be connected to each other through a bus bar (310).
[0116] In one embodiment, a bus bar (310) connected to the first lead tab portion (202a) of the first battery cell (201) and the first lead tab portion (202a) of the second battery cell (202) may be connected to a cooling plate (110) disposed on one side of the first group of battery cells (501). At this time, the bus bar (310) may be welded to the cooling plate (110) disposed on one side of the first group of battery cells (501).
[0117] In one embodiment, a bus bar (310) connected to the second lead tab portion (202b) of the third battery cell (203) and the second lead tab portion (202b) of the fourth battery cell (204) may be connected to a cooling plate (110) disposed between the first group of battery cells (501) and the second group of battery cells (502). At this time, the bus bar (310) may be welded to the cooling plate (110) disposed between the first group of battery cells (501) and the second group of battery cells (502).
[0118] In one embodiment, the battery cell (502) of the second group may include a fifth battery cell (205), a sixth battery cell (206) stacked in a first direction (X-axis direction) relative to the fifth battery cell (205) and positioned adjacent to the fifth battery cell (205), a seventh battery cell (207) stacked in a second direction (Y-axis direction) relative to the fifth battery cell (205) and positioned adjacent to the fifth battery cell (205), and an eighth battery cell (208) stacked in a first direction (X-axis direction) relative to the seventh battery cell (207) and positioned adjacent to the seventh battery cell (207).
[0119] In one embodiment, the first lead tab portion (202a) of the first polarity of the fifth battery cell (205) and the first lead tab portion (202a) of the first polarity of the sixth battery cell (206) can be connected to each other through a bus bar (310).
[0120] In one embodiment, the second lead tab portion (202b) of the second polarity of the seventh battery cell (207) and the second lead tab portion (202b) of the second polarity of the eighth battery cell (208) can be connected to each other through a bus bar (310).
[0121] In one embodiment, the second lead tab portion (202b) of the second polarity of the fifth battery cell (205) and the first lead tab portion (202a) of the first polarity of the seventh battery cell (207) can be connected to each other through a bus bar (310). In one embodiment, the second lead tab portion (202b) of the second polarity of the sixth battery cell (206) and the first lead tab portion (202a) of the first polarity of the eighth battery cell (208) can be connected to each other through a bus bar (310). In one embodiment, the second lead tab portion (202b) of the second polarity of the fifth battery cell (205) and the second lead tab portion (202b) of the second polarity of the sixth battery cell (206) can be connected to each other through a bus bar (310). In one embodiment, the second lead tab portion (202b) of the second polarity of the seventh battery cell (207) and the first lead tab portion (202a) of the first polarity of the eighth battery cell (208) can be connected to each other through a bus bar (310). In one embodiment, the bus bar (310) connected to the first lead tab portion (202a) of the fifth battery cell (205) and the first lead tab portion (202a) of the sixth battery cell (20) can be connected to a cooling plate (110) between the first group of battery cells (501) and the second group of battery cells (502). At this time, the bus bar (310) can be welded to the cooling plate (110) placed between the first group of battery cells (501) and the second group of battery cells (502).
[0122] In one embodiment, a bus bar (310) connected to the second lead tab portion (202b) of the seventh battery cell (207) and the second lead tab portion (202b) of the eighth battery cell (208) may be connected to a cooling plate (110) disposed on the other side of the second group of battery cells (502). At this time, the bus bar (310) may be welded to the cooling plate (110) disposed on the other side of the second group of battery cells (502).
[0123] FIG. 5a illustrates a battery assembly according to the present disclosure as viewed from one direction.
[0124] More specifically, FIG. 5a shows a portion of the battery assembly (100) illustrated in FIG. 4 as viewed from the Y-axis direction.
[0125] A plurality of battery cells (200) may include a first group of battery cells (501) arranged such that the lead tab portions (202a, 202b) face the upper case (104a) and a second group of battery cells (502) arranged such that the lead tab portions (202a, 202b) face the lower case (104b). The first group of battery cells (501) and the second group of battery cells (502) may be arranged alternately in a receiving space.
[0126] A protective member (220) may be disposed between a plurality of battery cells included in the first group of battery cells (501) and between a plurality of battery cells included in the second group of battery cells (502).
[0127] The lead tab portions of adjacent battery cells among the first group of battery cells (501) can be connected to each other through a bus bar (310). For example, the lead tab portions (202b) having the same polarity of adjacent battery cells among the first group of battery cells (501) can be connected to each other through a bus bar (310). The bus bar (310) can be welded to each of the lead tab portions (202b).
[0128] The lead tab portions of adjacent battery cells (502) in the second group can be connected to each other through a bus bar (310). For example, the lead tab portions (202b) having the same polarity of adjacent battery cells (502) in the second group can be connected to each other through a bus bar (310). The bus bar (310) can be welded to each of the lead tab portions (202b).
[0129] The cooling plate (110) can be connected to the bus bar (310). For example, the cooling plate (110) can be welded to the bus bar (310) (510).
[0130] The cooling plates (110) may be provided in multiple numbers. For example, the cooling plates (110) provided in multiple numbers may include a first cooling plate (110a), a second cooling plate (110b), and a third cooling plate (110c).
[0131] One end of the first cooling plate (110a) may be connected via a bus bar (310) to a lead tab portion (202b) having the same polarity as an adjacent battery cell among the first group of battery cells (501). The other end of the first cooling plate (110a) may not be connected to a lead tab portion of a second group of battery cells (502) adjacent to the first group of battery cells (501). For example, one end of the first cooling plate (110a) may be connected via a bus bar (310) to the lead tab portion (202b) of each of the third battery cell (203) and the fourth battery cell (204). The other end of the first cooling plate (110a) may not be connected to the lead tab portion (202b) of each of the seventh battery cell (207) and the eighth battery cell (208) included in the second group of battery cells (502).
[0132] One end of the second cooling plate (110b) may be connected via a bus bar (310) to a lead tab portion (202b) having the same polarity as an adjacent battery cell among the second group of battery cells (502). For example, one end of the second cooling plate (110b) may be connected via a bus bar (310) to the lead tab portion (202b) of each of the seventh battery cell (207) and the eighth battery cell (208). The other end of the second cooling plate (110b) may not be connected to a lead tab portion of a first group of battery cells (501) adjacent to the second group of battery cells (502).
[0133] FIG. 5b illustrates a battery assembly according to the present disclosure as viewed from one direction.
[0134] More specifically, FIG. 5b illustrates a portion of the battery assembly (100) shown in FIG. 4 as viewed from the -Y-axis direction. The -Y-axis may represent an axis symmetric to the origin of the Y-axis.
[0135] The cooling plates (110) may be provided in multiple numbers. For example, the cooling plates (110) provided in multiple numbers may include a first cooling plate (110a), a second cooling plate (110b), and a third cooling plate (110c).
[0136] One end of the first cooling plate (110a) may be connected via a bus bar (310) to a lead tab portion (202a) having the same polarity as an adjacent battery cell among the first group of battery cells (501). The other end of the first cooling plate (110a) may not be connected to a lead tab portion of a second group of battery cells (502) adjacent to the first group of battery cells (501). For example, one end of the first cooling plate (110a) may be connected via a bus bar (310) to the lead tab portion (202a) of each of the first battery cell (201) and the second battery cell (202). The other end of the first cooling plate (110a) may not be connected to the lead tab portion (202a) of each of the fifth battery cell (205) and the sixth battery cell (206) included in the second group of battery cells (502).
[0137] One end of the second cooling plate (110b) may be connected via a bus bar (310) to a lead tab portion (202a) having the same polarity as an adjacent battery cell among the second group of battery cells (502). For example, one end of the second cooling plate (110b) may be connected via a bus bar (310) to the lead tab portion (202a) of each of the fifth battery cell (205) and the sixth battery cell (206). The other end of the second cooling plate (110b) may not be connected to a lead tab portion of a first group of battery cells (501) adjacent to the second group of battery cells (502).
[0138] FIG. 6 illustrates a battery assembly according to the present disclosure as viewed from one direction.
[0139] More specifically, FIG. 6 shows a portion of the XY plane cut by the cross-section of B-B' shown in FIG. 4.
[0140] Each of the plurality of battery cells included in the first group of battery cells (501) may include a vent hole (610). The first group of battery cells (501) may have an insulating sheet (320) with a slit (320a) formed therein attached. The slit (320a) may be formed at a position corresponding to the vent hole (610).
[0141] Gas or heat (620) discharged from the vent hole (610) of the first group of battery cells (501) can be discharged through the vent hole (610) and the slit (320a) to the first exhaust passage. The first exhaust passage may be formed in the space between the receiving space of the plurality of battery cells (200) and the upper case (103a). Alternatively, the first exhaust passage may represent the space between the receiving space of the plurality of battery cells (200) and the upper case (103a). The first exhaust passage may be connected to the outside of the plurality of battery cells (200).
[0142] Each of the plurality of battery cells included in the second group of battery cells (502) may include a vent hole (630). The second group of battery cells (502) may have an insulating sheet (320) with a slit (320a) formed therein attached. Gas or heat (640) discharged from the vent hole (630) may be discharged to a second exhaust passage through the vent hole (630) and the slit (320a). The second exhaust passage may be formed in the space between the receiving space of the plurality of battery cells (200) and the lower case (103b). Alternatively, the second exhaust passage may represent the space between the receiving space of the plurality of battery cells (200) and the lower case (103b). The second exhaust passage may be connected to the outside of the plurality of battery cells (200).
[0143] FIG. 7 illustrates a battery assembly according to the present disclosure as viewed from one direction.
[0144] More specifically, FIG. 7 shows a portion of the XY plane cut by the cross-section of C-C' shown in FIG. 4.
[0145] A bus bar (310) may be connected to each of the lead tab portions (202a, 202b) of the first group of battery cells (501). The second lead tab portion (202b) of the second battery cell (202) included in the first group of battery cells (501) and the first lead tab portion (202a) of the fourth battery cell (204) may be connected to each other through the bus bar (310).
[0146] The first group of battery cells (501) can allow gas or heat (700) discharged from the vent hole (610) to be discharged into the first exhaust path through the vent hole (610) and the slit (320a).
[0147] The first exhaust passage may be formed in the space between the receiving space of a plurality of battery cells (200) and the upper case (103a). The first exhaust passage may be formed by being recessed in the upper case (103a) in a direction away from the receiving space. Alternatively, the first exhaust passage may represent the space between the receiving space of a plurality of battery cells (200) and the upper case (103a).
[0148] A bus bar (310) may be connected to each of the lead tab portions (202a, 202b) of the battery cell (502) of the second group. Although not illustrated, the second exhaust passage may be formed in the space between the receiving space of the plurality of battery cells (200) and the lower case (103b). The second exhaust passage may be formed by being recessed in the lower case (103b) in a direction away from the receiving space. Alternatively, the second exhaust passage may represent the space between the receiving space of the plurality of battery cells (200) and the lower case (103b).
[0149] FIG. 8 illustrates a battery assembly according to the present disclosure.
[0150] Specifically, for convenience of explanation, FIG. 8 is illustrated with some components of the battery assembly (100) of FIG. 1a omitted.
[0151] A battery assembly (100) according to the present disclosure may include a first cooling channel (250a) and a second cooling channel (250b) connected to a cooling plate (110).
[0152] The cooling plate (110) may be formed in a plate shape. The cooling plate (110) may include fastening members (810a, 810b) formed extending from a second direction (Y-axis direction).
[0153] The first cooling channel (250a) may include an insertion hole so that a fastening member (810a) can be inserted. The fastening member (810a) may have a protruding shape so that it can be inserted into the insertion hole.
[0154] The second cooling channel (250b) may include an insertion hole so that a fastening member (810b) can be inserted. The fastening member (810b) may have a protruding shape so that it can be inserted into the insertion hole.
[0155] The first cooling channel (250a) and the second cooling channel (250b) may be channels through which a cooling medium (cooling water) flows.
[0156] The first cooling channel (250a) may represent a channel through which a cooling medium flows to be introduced into the cooling plate (110) to cool a plurality of battery cells (200). The second cooling channel (250b) may represent a channel through which a cooling medium, whose temperature has increased after cooling a plurality of battery cells (200) discharged from the cooling plate (110), flows. The first cooling channel (250a) may be connected to a supply pipe (inlet) that supplies the cooling medium. The second cooling channel (250b) may be connected to a discharge pipe (outlet) that discharges the cooling medium.
[0157] Alternatively, the second cooling channel (250b) may represent a channel through which a cooling medium flows to be introduced into the cooling plate (110) to cool a plurality of battery cells (200). The first cooling channel (250a) may represent a channel through which a cooling medium, whose temperature has increased after cooling a plurality of battery cells (200) discharged from the cooling plate (110), flows. Alternatively, the first cooling channel (250a) may be connected to an outlet that discharges the cooling medium. The second cooling channel (250b) may be connected to an inlet that supplies the cooling medium.
[0158] For convenience of explanation, the first cooling channel (250a) is described as a channel through which a cooling medium to be introduced into the cooling plate (110) flows, and the second cooling channel (250b) is described as a channel through which a cooling medium to be introduced from the cooling plate (110) flows.
[0159] FIG. 9 illustrates a first cooling channel and a cooling plate according to the present disclosure.
[0160] More specifically, FIG. 9 shows an XY plane obtained by cutting the battery assembly (100) shown in FIG. 8 along D-D'.
[0161] In one embodiment, the cooling plate (110) may be connected to the first cooling channel (250a). In one embodiment, the cooling plate (110) may be connected to the first cooling channel (250a) through an O-ring (900).
[0162] A cooling medium (cooling water) (910) may flow through the first cooling channel (250a). The cooling plate (110) may include an open area (940) that can be opened and closed. The cooling plate (110) may allow the cooling medium (910) to flow (920) into the cooling plate (110) through the open area (940).
[0163] The cooling plate (110) can close the open area (940) when a cooling medium (910) is introduced (920) into the cooling plate (110) and a specified amount of cooling medium is introduced.
[0164] The cooling plate (110) can cool the battery cell (200) in contact with the cooling plate (110) through the cooling medium (910) introduced into the cooling plate (110).
[0165] FIG. 10 illustrates a second cooling channel and a cooling plate according to the present disclosure.
[0166] More specifically, FIG. 10 shows an XY plane cut along E-E' of the battery assembly (100) shown in FIG. 8.
[0167] In one embodiment, the cooling plate (110) may be connected to the second cooling channel (250b). In one embodiment, the cooling plate (110) may be connected to the second cooling channel (250b) through an O-ring.
[0168] A cooling medium (cooling water) (1010) whose temperature has increased after cooling a plurality of battery cells may flow through the second cooling channel (250b). The cooling plate (110) may include an open area (1040) that can be opened and closed. The cooling plate (110) may allow the cooling medium (1010) whose temperature has increased to flow out (1020) from the cooling plate (110) to the second cooling channel (250b) through the open area (1040).
[0169] The present disclosure may be modified and implemented in various forms, and its scope of rights is not limited to the embodiments described above. Accordingly, if a modified embodiment includes the components of the claims of the present disclosure, it should be considered to fall within the scope of the present disclosure. Explanation of the symbols
[0170] 100: Battery assembly 104a: Upper case 104b: Lower case 105: Insulating member 110: Cooling plate 220: Protection absence 200: Battery cell 250a: 1st cooling channel 250b: Second cooling channel 310: Busbar 320: Insulation sheet 610, 630: Vent Hall
Claims
Claim 1 A battery assembly comprising: a receiving case forming a receiving space inside; a plurality of battery cells arranged along a predetermined stacking direction in the receiving space, each cell case, and an electrode assembly arranged in the cell case, and a lead tab portion electrically connected to the electrode assembly and protruding outward from the cell case; wherein the plurality of battery cells is alternately arranged along the stacking direction, the first group of battery cells in which the lead tab portion protrudes to one side of the cell case and the second group of battery cells in which the lead tab portion protrudes to the other side of the cell case; a first exhaust passage formed between the receiving case and the receiving space facing the lead tab portion of the first group of battery cells; and a second exhaust passage formed between the receiving case and the receiving space facing the lead tab portion of the second group of battery cells. Claim 2 A battery assembly according to claim 1, further comprising cooling plates disposed respectively on one side of the first group of battery cells, between the first group of battery cells and the second group of battery cells, and on the other side of the second group of battery cells. Claim 3 A battery assembly according to claim 2, further comprising: a first busbar connecting the cooling plate disposed on one side of the first group of battery cells and the lead tab portion of the first group of battery cells; and a second busbar connecting the cooling plate disposed between the first group of battery cells and the second group of battery cells and the lead tab portion of the second group of battery cells. Claim 4 In paragraph 3, the cooling plate disposed on one side of the first busbar and the first group of battery cells, and the cooling plate disposed between the second busbar and the first group of battery cells and the second group of battery cells are each welded to form a battery assembly. Claim 5 A battery assembly having an insulating member attached to each of the first busbar and the second busbar in paragraph 3. Claim 6 In claim 5, the insulating member comprises a battery assembly comprising any one of mica, glass fiber, and ceramic fiber, or a combination thereof. Claim 7 In claim 1, the battery cell of the first group is a battery assembly that forms a first vent hole to allow gas generated inside the battery cell of the first group to be discharged. Claim 8 A battery assembly according to claim 7, wherein a first insulating sheet is attached to the surface of the cell case of the first group of battery cells having the first vent hole formed therein. Claim 9 In claim 8, the first insulating sheet is a battery assembly having a slit formed at a position corresponding to the first vent hole so that gas discharged from the first vent hole is discharged to the outside. Claim 10 In claim 1, the battery cell of the second group is a battery assembly that forms a second vent hole to allow gas generated inside the battery cell of the second group to be discharged. Claim 11 A battery assembly according to claim 10, wherein a second insulating sheet is attached to the surface of the cell case of the second group of battery cells having the second vent hole formed therein. Claim 12 In claim 11, the second insulating sheet is a battery assembly having a slit formed at a position corresponding to the second vent hole so that gas discharged from the second vent hole is discharged to the outside. Claim 13 A battery assembly according to claim 1, wherein each of the first group of battery cells and the second group of battery cells comprises a plurality of battery cells, and further comprises a plate-shaped first protective member disposed between the plurality of battery cells included in the first group of battery cells; and a plate-shaped second protective member disposed between the plurality of battery cells included in the second group of battery cells.