Battery module, and electrode lead welding method of battery cells included in battery module

Abstract

A battery module according to the present invention comprises: a cell stack composed of a plurality of battery cells, each having an electrode lead; a cover frame having a slit through which the electrode lead passes, and covering a front part or a rear part of the cell stack; and a lead bonding part, which is provided on the outside of the cover frame, is formed by overlapping the electrode leads of the battery cells, and has at least one overlapped portion that is welded, wherein the cover frame provides pressing force from the rear to the front of the lead bonding part so as to bring the electrode leads overlapping the lead bonding part into close contact with each other.

Description

A method for welding electrode leads of a battery module and battery cells included in the battery module

[0001] The present invention relates to a battery, and more particularly, to a battery module in which electrode leads of battery cells are welded without a bus bar, and a method for welding electrode leads of the battery cells.

[0002] This application claims priority to Korean Patent Application No. 10-2024-0096923, filed on July 23, 2024, and all contents disclosed in the specification and drawings of the said application are incorporated herein by reference.

[0003] A semi-permanent battery that converts electrical energy into chemical energy and can be repeatedly charged and discharged is called a secondary battery, distinguishing it from a primary battery that cannot be reused after a single use.

[0004] Secondary batteries include lithium secondary batteries, nickel-cadmium (Ni-Cd) batteries, lead-acid batteries, nickel-metal hydride (Ni-MH) batteries, zinc-air batteries, and alkaline manganese batteries. Of these, lead-acid batteries and lithium secondary batteries are the most actively commercialized secondary batteries.

[0005] In particular, lithium secondary batteries have recently been actively utilized as batteries for electric vehicles due to their advantages, including high energy storage density, lightweight and miniaturized designs, excellent safety, low discharge rates, and long lifespan. Lithium secondary batteries are generally classified into cylindrical, prismatic, and pouch types depending on their manufacturing form, and their applications extend beyond electric vehicle batteries to include ESS batteries and other electrical devices.

[0006] Currently, a single lithium secondary battery (cell) cannot produce sufficient power to power an electric vehicle. To utilize secondary batteries as an energy source for electric vehicles, multiple lithium-ion battery cells must be connected in series and / or parallel to form a battery module. Typically, these battery modules are connected in series and functionally maintained by a battery management system (BMS), a cooling system, a battery disconnection unit (BDU), electrical wiring cables, and other components, forming a battery pack.

[0007] Meanwhile, as illustrated in Fig. 1, when a battery module is configured with a pouch-type secondary battery, the electrode leads (1a, 1b) of the pouch-type secondary battery are laser welded to a bus bar (3). Here, the bus bar (3) refers to a conductor formed of a metal material such as copper and generally manufactured in a bar or square shape.

[0008] Pouch-type secondary batteries form a cell stack in which a wide surface is erected and stacked in one direction, and a busbar frame (2) can be arranged at the front and / or rear of the cell stack. The busbar frame (2) is made of an electrically insulating material, has a slit through which electrode leads (1a, 1b) can pass, and is provided so that a plurality of busbars (3) can be mounted on the outer surface. That is, the busbars (3) can be mounted on the outer surface of the busbar frame (2), and a plurality of electrode leads (1a, 1b) are welded to each busbar, so that secondary batteries can be connected in series and / or in parallel.

[0009] In addition, voltage information of the secondary batteries in the battery module is transmitted to the BMS through a sensing member (4) connected to each bus bar (3), and the BMS monitors the status of each secondary battery based on this and controls charging and discharging of the secondary batteries.

[0010] As the sensing member (4), a harness wire, an FFC (Flat Flexible Cable), or an FPCB (Flexible Printed Circuit Board) is used. Conventionally, one side of a sensing plate (5) is pressed to the end of the sensing member (4), and the other side of the sensing plate (5) is welded to a bus bar (3). However, the battery module manufacturing method of connecting the electrode leads (1a, 1b) and the sensing plate (5) via the bus bars (3) has the disadvantage of increasing the manufacturing cost and weight.

[0011] The present invention was created to solve the above-described problem, and its first purpose is to provide a battery module in which battery cells are electrically connected by welding electrode leads of battery cells without using a bus bar.

[0012] In addition, the present invention aims to provide an electrode lead welding method capable of welding electrode leads in close contact without a bus bar.

[0013] The technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention described below.

[0014] According to one aspect of the present invention, a battery module may be provided, comprising: a cell stack comprising a plurality of battery cells, each having an electrode lead; a cover frame having a slit through which the electrode leads pass and covering a front or rear portion of the cell stack; and a lead joint provided on an outer side of the cover frame and formed by overlapping the electrode leads of the battery cells and at least a portion of the overlapping is welded, wherein the cover frame includes a lead support unit that provides a pressing force from a rear surface of the lead joint toward a front surface to bring the electrode leads overlapping the lead joint into close contact.

[0015] The above lead support unit may include an elastic member that is coupled to the plate surface of the cover frame and elastically presses the lead joint.

[0016] The elastic member may include a support block that contacts the back surface of the lead joint; and a spring having one end connected to the plate surface of the cover frame and the other end connected to the support block.

[0017] The support block may include a spring connecting portion connected to the spring; a first lead supporting portion extending from one side of the spring connecting portion toward the lead joint; and a second lead supporting portion spaced apart from the first lead supporting portion and extending from the other side of the spring connecting portion toward the lead joint.

[0018] The above spring connection portion may be configured to be spaced apart from the lead connection portion by a predetermined distance.

[0019] The cover frame includes a first guide plate and a second guide plate that are spaced apart from each other and arranged side by side and protrude from a surface of the cover frame, and the elastic member can be arranged in a space between the first guide plate and the second guide plate.

[0020] The elastic member may include a support block that contacts the back surface of the lead joint; and a spring having one end connected to the plate surface of the cover frame and the other end connected to the support block, wherein the support block may be configured to have a width corresponding to the gap between the first guide plate and the second guide plate.

[0021] The above cover frame may be provided with the slit on at least one of the left and right sides of the lead support unit.

[0022] According to another aspect of the present invention, there is provided an electrode lead welding method for joining electrode leads between battery cells, the method comprising: preparing a cover frame including a slit through which an electrode lead can pass and an elastic member capable of elastically pressing the electrode lead; inserting two or more of the electrode leads into the slit and pulling them out from the rear to the front of the cover frame; compressing the elastic member; forming a lead joint by bending two or more of the electrode leads passing through the slit so as to overlap each other, and positioning the lead joint in front of the compressed elastic member; releasing the compression of the elastic member so that a back surface of the lead joint is pressed and pressing a front surface of the lead joint with a welding jig so that a front surface of the lead joint is pressed; and performing welding on the lead joint through a through hole provided in the welding jig.

[0023] The elastic member may include a support block that contacts the back surface of the lead joint; and a spring having one end connected to the plate surface of the cover frame and the other end connected to the support block.

[0024] The above support block is formed convexly with respect to the back surface of the lead joint and has a pocket space on the inside, and a spring compression jig is inserted into the pocket space and the support block is pushed with the spring compression jig to compress the spring in the direction of the plate surface of the cover frame.

[0025] The cover frame includes a first protrusion and a second protrusion that protrude from the plate surface of the cover frame and are spaced apart from each other, and the elastic member can be disposed in a space between the first protrusion and the second protrusion.

[0026] The elastic member may include a support block that contacts the back surface of the lead joint; and a spring having one end connected to the plate surface of the cover frame and the other end connected to the support block, wherein the support block may be configured to have a width corresponding to the gap between the first protrusion and the second protrusion.

[0027] The slit may be provided on at least one of the left and right sides of the elastic member based on the elastic member.

[0028] According to another aspect of the present invention, a battery pack including the above-described battery module can be provided.

[0029] According to the present invention, a battery module can be provided in which battery cells are electrically connected by welding electrode leads of battery cells without using a bus bar.

[0030] In addition, an electrode lead welding method capable of welding electrode leads in close contact without a bus bar can be provided.

[0031] The effects of the present invention are not limited to the effects described above, and effects not mentioned can be clearly understood by a person having ordinary skill in the art to which the present invention pertains from this specification and the attached drawings.

[0032] FIG. 1 is a drawing showing a part of a battery module according to the prior art, showing a bus bar and electrode leads welded to the bus bar.

[0033] Fig. 2 is a cross-sectional view of a portion of a battery module according to the prior art.

[0034] FIG. 3 is a drawing showing the main configuration of a battery module according to one embodiment of the present invention.

[0035] FIG. 4 is a drawing showing the connection structure of a cover frame and electrode leads in a battery module according to one embodiment of the present invention.

[0036] FIG. 5 is a drawing illustrating a cover frame according to one embodiment of the present invention.

[0037] FIG. 6 is a drawing showing the main configuration of a lead support portion of a cover frame according to one embodiment of the present invention.

[0038] Figures 7 to 9 are process diagrams illustrating an electrode lead welding process according to one embodiment of the present invention.

[0039] Fig. 10 is a perspective view corresponding to Fig. 9, showing a lead joint pressurized by a welding jig and an elastic member.

[0040] Figures 11 and 12 are drawings corresponding to Figures 8 and 9, and are process drawings illustrating the welding process of six electrode leads.

[0041] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, it should be noted that the terms and words used in this specification and claims should not be interpreted as limited to their conventional or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

[0042] Since the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art, the shapes and sizes of components in the drawings may be exaggerated, omitted, or schematically illustrated for clearer explanation. Accordingly, the sizes and proportions of each component do not fully reflect the actual sizes or proportions.

[0043] FIG. 3 is a drawing showing the main configuration of a battery module according to one embodiment of the present invention, FIG. 4 is a drawing showing the connection structure of a cover frame and electrode leads in a battery module according to one embodiment of the present invention, and FIG. 5 is a drawing showing a cover frame according to one embodiment of the present invention.

[0044] Referring to FIGS. 3 to 5, a battery module according to one embodiment of the present invention includes a cell stack (100), a cover frame (200), and a voltage sensing unit (300).

[0045] The above cell stack (100) is an assembly composed of battery cells (110). The battery cells (110) are each erected in the vertical direction (±Z) and stacked in the left-right direction (±X) to form the cell stack (100).

[0046] Buffer pads or cooling fins may be further added between the battery cells (110). The buffer pads or cooling fins may function to absorb shock or efficiently release heat from each battery cell (110) to the outside. Pouch-type battery cells (110) may be employed as the battery cells (110).

[0047] The above pouch-type battery cell (110) is not illustrated in detail, but may be composed of an electrode assembly, an electrolyte, and a pouch outer material for sealing and storing them. The electrode assembly has a stack structure in which a positive electrode plate / separator / negative electrode plate / separator are repeatedly laminated, and the positive electrode plate and the negative electrode plate are provided with electrode tabs, and at least one electrode tab is connected to an electrode lead (111). The electrode lead (111) extends from the inside to the outside of the pouch outer material and functions as an electrode terminal of the battery cell (110). Here, the electrode lead (111) collectively refers to the positive electrode lead (111a) and the negative electrode lead (111b). The pouch outer material may be configured to include a metal thin film, such as an aluminum thin film, in order to protect internal components such as the electrode assembly and the electrolyte, and to improve electrochemical properties of the electrode assembly and the electrolyte and heat dissipation properties. The above aluminum thin film may be interposed between an insulating layer formed of an insulating material and an internal adhesive layer to ensure electrical insulation.

[0048] In the battery module according to the present invention, the electrode leads (111) of adjacent battery cells (110) are overlapped with each other in a predetermined pattern so that the battery cells (110) can be connected in series or in series and parallel.

[0049] For example, in the cell stack (100), one battery cell (110) is referred to as the Nth battery cell (110), followed by N+1, N+2... battery cells (110) in that order, and it is assumed that the adjacent battery cells (110) are arranged such that the positive leads (111a) and the negative leads (111b) face opposite directions. The positive lead (111a) of the Nth battery cell (110) and the negative lead (111b) of the N+1 cell are covered on the front side of the cell stack (100). In addition, the positive lead (111a) of the N+1 battery cell (110) and the negative lead (111b) of the N+2 battery cell (110) are covered on the rear side of the cell stack (100). By covering the electrode leads (111) of the battery cells (110) in this pattern and joining the electrode leads (111) using the electrode lead welding method described later, the battery cells (110) can be connected in series.

[0050] As another example, two to three consecutive battery cells (110) are grouped together, and the same group is arranged with the polarities facing the same direction, and the different groups are arranged with the polarities facing opposite directions. Then, by joining the electrode leads (111) in a pattern in which the positive leads (111a) of one group and the negative leads (111b) of another group are overlapped and then welded together, the battery cells (110) can be connected in series and in parallel.

[0051] In particular, a battery module according to one embodiment of the present invention is configured to electrically connect battery cells (110) by welding electrode leads (111) without a bus bar (see FIGS. 1 and 2), which is a metal conductor according to the prior art, using the electrode lead (111) welding method described below.

[0052] That is, unlike the conventional method, the battery module according to one embodiment of the present invention has a first welding portion (W1) where the electrode leads (111) of the battery cells (110) to be connected are overlapped and directly welded, and the overlapped electrode leads (111) are joined to each other. There may be one or more first welding portions. In other words, the battery module includes a lead joining portion (120) where the electrode leads (111) of the battery cells (110) are overlapped in a predetermined pattern and at least a portion of the overlapped electrode leads are welded. As the welding method performed at this time, for example, any one of laser welding, ultrasonic welding, and resistance welding may be adopted.

[0053] A cover frame (200) according to one embodiment of the present invention can be placed on the front and rear sides of the cell stack (100) as a means for supporting the cell stack (100).

[0054] The cover frame (200) has slits (220) formed at predetermined intervals along the stacking direction (±X) of the battery cells (110). The electrode leads (111) of the battery cells (110) can be extended to the outside of the cover frame (200) through the slits (220). A portion of the electrode leads (111) that have passed through the slits (220) can be bent to face the plate surface of the cover frame (200). At this time, at least a portion of two or more electrode leads (111) to be electrically connected is overlapped on the outside of the cover frame (200) to form a lead joint (120). The electrode leads (111) forming the lead joint (120) can be configured to not be separated from each other by being joined by an electrode lead (111) welding method described later.

[0055] The above cover frame (200) may include a plurality of lead support units (210) provided at predetermined intervals along the stacking direction (±X) of the battery cells (110), as shown in FIG. 5. The lead support unit (210) is a component that supports the lead joint (120) during the welding process.

[0056] The lead support unit (210) may be configured to provide a pressing force from the rear surface of the lead joint (120) toward the front surface so that a gap does not occur between the electrode leads (111) of the lead joint (120). For example, the lead support unit (210) may include an elastic member that is coupled to the plate surface of the cover frame (200) and elastically presses the lead joint (120).

[0057] The above elastic member may include a support block (211) and a spring (212), as shown in FIG. 6.

[0058] The above support block (211) may be configured to be in contact with the back surface of the lead joint (120). For example, the support block (211) may be provided to have a length corresponding to the width of the electrode lead (111) so as to stably support the lead joint (120).

[0059] In addition, the support block (211) may include a spring connection portion (211a) connected to a spring (212), a first lead support portion (211b) extending from one side of the spring connection portion (211a) toward the lead joint portion (120), and a second lead support portion (211c) spaced apart from the first lead support portion (211b) and extending from the other side of the spring connection portion (211a) toward the lead joint portion (120).

[0060] The first lead support portion (211b) and the second lead support portion (211c) may be configured to have surfaces that face each other and make direct contact with the lead joint portion (120). The first lead support portion (211b) and the second lead support portion (211c) may be configured to support the back surface of the lead joint portion (120) while pressing the lead joint portion (120) by the elastic force of the spring (212). In addition, the spring connection portion (211a) may be configured to be spaced apart from the lead joint portion (120) by a predetermined distance.

[0061] The support block (211) of this embodiment is manufactured in an approximately 'U' shape, and a pocket space (S) can be formed between the support block (211) and the lead joint (120). As will be described later, by providing the pocket space (S), the support block (211) can be prevented from being joined together with the electrode leads (111).

[0062] The spring (212) may be a coil spring (212) employed as a means for providing a pressing force to the lead joint (120). The spring (212) may be replaced with a plate spring instead of the coil spring (212). The spring (212) may be configured such that one end is connected to the plate of the cover frame (200) and the other end is connected to the support block (211). A plurality of the springs (212) may be provided along the longitudinal direction (Z direction) of the support block (211).

[0063] Referring again to FIGS. 5 and 6, the cover frame (200) includes a first guide plate (230) and a second guide plate (240) that are spaced apart from each other and arranged side by side and protrude from the surface of the cover frame (200). The elastic member described above may be arranged in the space between the first guide plate (230) and the second guide plate (240).

[0064] The first guide plate (230) and the second guide plate (240) may serve to guide the movement of the elastic member so that, when the elastic member is compressed or extended, the elastic member moves left and right without being twisted by the first guide plate (230) and the second guide plate (240). The first guide plate (230) and the second guide plate (240) may be configured so that the gap therebetween corresponds to the width of the support block (211).

[0065] The first guide plate (230) and the second guide plate (240) are configured to protrude further than the support block (211) at least when the spring (212) is fully compressed. In addition, the first guide plate (230) and the second guide plate (240) are configured to have the same protruding length relative to the plate surface of the cover frame (200).

[0066] The first guide plate (230) and the second guide plate (240) can serve to support one side and the other side of the lead joint (120) together with the first lead support portion (211b) and the second lead support portion (211c) of the support block (211).

[0067] In the cover frame (200), the slit (220) may be provided on at least one of the left and right sides of the lead support unit (210), i.e., the elastic member. For example, in the present embodiment, the slit (220) may be provided on the left side of the first guide plate (230) or the right side of the second guide plate (240) that protects and guides the elastic member. The electrode leads (111) each pass through the adjacent slits (220) and are bent toward the first guide plate (230) or the second guide plate (240) to form a lead joint (120) at the front of the elastic member.

[0068] Meanwhile, the voltage sensing unit (300) refers to a component that senses the node voltage of electrically connected battery cells (110) and transmits voltage information of each battery cell (110) to a BMS (not shown, Battery Management System). The BMS can monitor the status of the battery cells (110) through the voltage sensing unit (300) and control the charging and discharging of the battery cells (110).

[0069] The voltage sensing unit (300) may include a signal transmission member (310) and a sensing plate (320) (see FIG. 3). The voltage sensing unit (300) may be implemented as a film cable, such as, for example, a flexible printed circuit board (FPCB) or a flat flexible cable (FFC).

[0070] The above FPCB can be manufactured by placing a copper-clad laminate on a base film, laminating a dry film, and forming conductor lines at regular intervals through exposure, development, and etching processes, and then bonding a coverlay film. In addition, the FFC can be manufactured by arranging conductor lines at regular intervals on a base film and laminating a coverlay thereon.

[0071] This voltage sensing unit (300) in the form of a film cable has excellent conductive performance of the conductor wires and the insulation between the conductor wires is perfectly secured with a single insulating film, so that a large amount of signal processing is possible with a minimum volume.

[0072] In the present embodiment, the signal transmission member (310) of the voltage sensing unit (300) may be configured to extend in the longitudinal direction (±Y direction) of the cell stack (100) from the upper portion of the cell stack (100). Sensing plates (320) connected to lead overlapping portions may be provided at both ends of the voltage sensing unit (300). In addition, a connector may be provided at one side of the voltage sensing unit (300). The connector may be connected to a BMS by a cable connector (not shown).

[0073] Each of the sensing plates (320) can be connected one-to-one to a predetermined lead joint (120) (see FIG. 4). At this time, the sensing plate (320) can be directly welded to the lead joint (120). That is, the battery module according to the present embodiment has a first welding portion (W1) where the positive lead (111a) and the negative lead (111b) are welded, and a second welding portion (W2) where the sensing plate (320) and the lead joint (120) are welded. That is, the battery module according to one embodiment of the present invention has a structure in which there is no bus bar, and between the electrode leads (111) and between the electrode leads (111) and the sensing plate (320) are welded.

[0074] Hereinafter, with reference to FIGS. 7 to 10, a welding method of an electrode lead (111) according to the present invention will be described.

[0075] The electrode lead (111) welding method according to the present invention can be used to manufacture a battery module in which electrode leads (111) are welded together without a bus bar, as described above.

[0076] The above electrode lead (111) welding method comprises the steps of: preparing a cover frame (200) including a slit (220) through which the electrode lead (111) can pass and an elastic member capable of elastically pressing the electrode lead (111); inserting two or more of the electrode leads (111) into the slit (220) and pulling them out from the rear to the front of the cover frame (200); compressing the elastic member; forming a lead joint (120) by bending two or more of the electrode leads (111) that have passed through the slit (220) so as to overlap each other, and positioning the lead joint (120) in front of the compressed elastic member; The method may include a step of releasing the compression of the elastic member so that the back surface of the lead joint (120) is pressed, and pressing the front surface of the lead joint (120) with a welding jig (20) so that the front surface of the lead joint (120) is pressed; and a step of performing welding on the lead joint (120) through a hole (21) provided in the welding jig (20).

[0077] More specifically, when two battery cells (110) are to be connected in series, for example, the electrode leads (111) are welded using the electrode lead (111) welding method according to the present embodiment as follows.

[0078] First, the cover frame (200) described above is prepared, and the positive lead (111a) of one battery cell (110) and the negative lead (111b) of the other battery cell (110) are pulled out from the rear to the front of the cover frame (200) through the corresponding slits (220).

[0079] Next, as shown in Fig. 8, the spring (212) is compressed to push the support block (211) into the space between the first guide plate (230) and the second guide plate (240). At this time, a spring (212) compression jig (30) may be used. The spring (212) compression jig (30) is provided in a rod shape and can be inserted into the pocket space (S) of the support block (211). The spring (212) compression jig (30) is moved toward the plate surface of the cover frame (200) to compress the spring (212). Here, the pocket space (S) refers to an empty space surrounded by the first lead support portion (211b), the second lead support portion (211c), and the spring connection portion (211a) as described above.

[0080] Then, the positive lead (111a) and the negative lead (111b) are bent so that they overlap each other to form a lead joint (120). At this time, the back surface of the lead joint (120) is made to make even contact with the ends of the first guide plate and the second guide plate.

[0081] Next, as shown in Fig. 9, the welding jig (20) is pressed against the front surface of the lead joint (120), and the spring (212) compression jig (30) is separated from the support block (211) to release the compressed state of the spring (212). Then, the back surface of the lead joint (120) is pressed by the first lead support (211b) and the second lead support (211c) of the support block (211), and the front surface of the lead joint (120) can be pressed by the welding jig (20). In this case, the positive lead (111a) and the negative lead (111b) are pressed against each other, and no gap occurs between them. In this way, while the positive lead (111a) and the negative lead (111b) are in close contact, a laser is irradiated to the lead joint portion (120) using, for example, a laser welder (40) to laser weld the positive lead (111a) and the negative lead (111b). At this time, the laser is irradiated to the center of the lead joint portion (120). Since there is a pocket space (S) of the support block (211) behind the center of the lead joint portion (120), even if the positive lead (111a) and the negative lead (111b) are melted, the heat is not directly transferred to the support block (211). This can prevent the support block (211) and the electrode lead (111) from being integrally joined.

[0082] The above welding jig (20), as illustrated in FIG. 10, may be provided in a roughly box shape and may have a through hole (21) formed therethrough. A plurality of the through holes (21) may be provided. The plurality of through holes (21) may be partitioned by a partition wall. The through hole (21) may serve as a passage for introducing a welding means such as a laser beam, an ultrasonic horn, a welding rod, etc., and may prevent sputtering or the like that may be generated during welding from flying away. The welding jig (20) may include a lower surface that can come into direct contact with the lead joint (120). In addition, the welding jig (20) may be provided in a size corresponding to the lead joint (120) so as to pressurize the lead joint (120) as a whole.

[0083] FIG. 11 and FIG. 12 are drawings corresponding to FIG. 8 and FIG. 9, and are process drawings illustrating the welding process of six electrode leads (111).

[0084] By using the electrode lead (111) welding method according to the present invention, the electrode leads (111) of three or more battery cells (110) can be welded and electrically connected.

[0085] For example, as shown in Fig. 11, the positive leads (111a) of three battery cells (110) are pulled out to the front of the cover frame (200) through the same slit (220) and covered. Then, the negative leads (111b) of the other three battery cells (110) are pulled out to the front of the cover frame (200) through another slit (220) and covered.

[0086] Next, as described above, the first guide plate (230) and the second guide plate (240) are pushed into the space between them, and the three positive leads (111a) and the three negative leads (111b) are bent so as to overlap each other to form a lead joint (120).

[0087] Next, the back surface of the lead joint (120) is pressed with an elastic member, and the front surface of the lead joint (120) is pressed with a welding jig (20) to perform laser welding while the six electrode leads (111) are in close contact. Then, the six battery cells (110) form a parallel and series-connected structure (3P2S).

[0088] Meanwhile, the battery pack according to the present invention may include one or more battery modules according to the present invention. Furthermore, in addition to the battery modules, the battery pack according to the present invention may further include a pack case for storing the battery modules, and various devices for controlling the charging and discharging of each battery module, such as a master BMS, a current sensor, and a fuse.

[0089] The battery module according to the present invention can be applied to automobiles such as electric vehicles or hybrid vehicles. That is, the automobiles can include the battery module according to the present invention.

[0090] As described above, although the present invention has been described by limited embodiments and drawings, the present invention is not limited thereto, and various modifications and variations are possible by a person having ordinary skill in the art to which the present invention pertains within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below.

[0091] When terms indicating directions such as up, down, left, right, front, and back are used in this specification, these terms indicate relative positions and are only for convenience of explanation, and it is obvious to those skilled in the art that these terms may vary depending on the position of the target object or the position of the observer.

Claims

1. A cell stack comprising a plurality of battery cells, each having an electrode lead; A cover frame having a slit through which the electrode lead passes and covering the front or rear portion of the cell stack; and It includes a lead joint provided on the outside of the cover frame and formed by covering the electrode leads of the battery cells and welding at least a portion of the covering, The above cover frame, A battery module characterized by including a lead support unit that provides a pressing force from the back side of the lead joint toward the front side to adhere the electrode leads covered at the lead joint.

2. In paragraph 1, The above lead support unit is, A battery module characterized by including an elastic member that is bonded to the plate surface of the cover frame and elastically presses the lead joint.

3. In paragraph 2, The above elastic member is, A support block in contact with the back surface of the above lead joint; and A battery module characterized in that it includes a spring, one end of which is connected to the plate surface of the cover frame and the other end of which is connected to the support block.

4. In paragraph 3, The above support block is, A spring connecting portion connected to the above spring; A first lead support extending from one side of the spring connection toward the lead joint; and A battery module characterized by comprising a second lead support portion spaced apart from the first lead support portion and extending from the other side of the spring connection portion toward the lead joint portion.

5. In paragraph 4, A battery module characterized in that the spring connecting portion is configured to be spaced apart from the lead connecting portion by a predetermined distance.

6. In paragraph 2, The above cover frame, It includes a first guide plate and a second guide plate spaced apart from each other and arranged side by side and protruding from the surface of the cover frame, The above elastic member A battery module characterized in that it is arranged in the space between the first guide plate and the second guide plate.

7. In paragraph 6, The elastic member includes a support block in contact with the back surface of the lead joint; and a spring having one end connected to the plate surface of the cover frame and the other end connected to the support block. A battery module, characterized in that the support block has a width corresponding to the gap between the first guide plate and the second guide plate.

8. In paragraph 1, The above cover frame, A battery module characterized in that the slit is provided on at least one of the left and right sides of the lead support unit.

9. An electrode lead welding method for joining electrode leads between battery cells, A step of preparing a cover frame including a slit through which an electrode lead can pass and an elastic member capable of elastically pressing the electrode lead; A step of inserting two or more of the above electrode leads into the above slit and pulling them out from the rear to the front of the cover frame; A step of compressing the above elastic member; A step of forming a lead joint by bending two or more of the electrode leads passing through the slit so as to overlap each other, and positioning the lead joint in front of the compressed elastic member; A step of releasing the compression of the elastic member so that the back surface of the lead joint is pressed and pressing the front surface of the lead joint with a welding jig so that the front surface of the lead joint is pressed; and An electrode lead welding method characterized by including a step of performing welding on the lead joint through a through hole provided in the welding jig.

10. In paragraph 9, The above elastic member is, An electrode lead welding method characterized by comprising: a support block in contact with the back surface of the lead joint; and a spring having one end connected to the plate surface of the cover frame and the other end connected to the support block.

11. In paragraph 10, The above support block is, The back surface of the above lead joint is formed convexly and has a pocket space on the inside, An electrode lead welding method characterized in that a spring compression jig is inserted into the pocket space and the support block is pushed with the spring compression jig to compress the spring toward the plate surface of the cover frame.

12. In paragraph 9, The above cover frame, It includes a first protrusion and a second protrusion that protrude from the plate surface of the cover frame and are spaced apart from each other, The above elastic member is, An electrode lead welding method characterized in that it is arranged in a space between the first protrusion and the second protrusion.

13. In paragraph 12, The elastic member includes a support block in contact with the back surface of the lead joint; and a spring having one end connected to the plate surface of the cover frame and the other end connected to the support block. An electrode lead welding method, characterized in that the support block has a width corresponding to the gap between the first protrusion and the second protrusion.

14. In paragraph 9, An electrode lead welding method characterized in that the slit is provided on at least one of the left and right sides of the elastic member based on the elastic member.

15. A battery pack comprising a battery module according to any one of claims 1 to 8.

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