Battery module

Abstract

Provided is a battery module that makes it possible to prevent or suppress concentration of stress on a tab connection portion between adjacent battery cells. In this battery module (110), a plurality of battery cells (1) in which the stacking-direction thickness changes due to charging and discharging are stacked. In the adjacent battery cells (1), in which tab leads (31, 32) are connected to each other, a tab connection portion that connects the tab leads (31, 32) is connected at a position that is displaced toward one side, and the tab lead (31) on the side where the stacking-direction distance is long due to the displacement has a flexible curved portion (40) that is curved so as to protrude outward in a direction orthogonal to the stacking direction of the battery cells (1).

Description

Battery module

[0001] The present invention relates to a battery module in which a plurality of battery cells whose thickness changes with charge and discharge are stacked, and in particular to a tab lead connection structure suitable for lithium deposition-type all-solid-state batteries.

[0002] The battery cells that make up this type of battery module include a laminated electrode assembly and a pair of exterior housings that sandwich the laminated electrode assembly from both sides in the thickness direction. The laminated electrode assembly is composed of multiple flat-shaped unit cells, each of which has a positive electrode, an electrolyte, and a negative electrode stacked in the thickness direction. The battery cells have positive and negative electrode tab leads. These tab leads are pulled out to the sides of the battery cells from the joint that joins the pair of exterior housings (see, for example, Patent Document 1).

[0003] Special Publication No. 2012-525664

[0004] However, this type of battery cell changes in thickness with charging and discharging, and the distance between the tab leads of adjacent battery cells also changes accordingly, which can result in excessive stress being generated in the tab leads of adjacent battery cells and in the tab connections connecting the tab leads to each other.

[0005] In contrast, in the technology described in Patent Document 1, the tab leads 130 of adjacent battery cells 1000 are symmetrical and connected at their centers, as shown in Fig. 9. Therefore, stress is applied in the peeling direction of the tab connection portion 140 in response to expansion and contraction in the cell stacking direction, and displacement due to expansion and contraction of the battery cells 1000 during charge and discharge is concentrated on the central tab connection portion 140, which may cause damage to the tab connection portion 140 due to repeated stress caused by charge and discharge. Therefore, there is still room for further study to find a tab lead connection structure suitable for all-solid-state batteries.

[0006] The present invention has been made in response to these problems, and has as its object to provide a battery module that can prevent or suppress stress concentration at the tab connections between adjacent battery cells.

[0007] In order to solve the above-described problems, a battery module according to one aspect of the present invention provides a battery module comprising: a laminated electrode body formed by stacking, in the thickness direction, a plurality of flat-shaped unit cells, each of which has a positive electrode, an electrolyte, and a negative electrode stacked thereon; a pair of exterior bodies that sandwich and enclose the laminated electrode body from both sides in the thickness direction; and tab leads drawn out laterally from a joint between the pair of exterior bodies, the battery module comprising a plurality of battery cells stacked in the stacking direction; and adjacent battery cells, between which the tab leads are connected, have tab connection portions connecting the tab leads of adjacent battery cells connected at a position biased toward one of the battery cells with respect to the abutment surfaces of the exterior bodies of the adjacent battery cells, and further, the tab lead on the side that is farther apart in the stacking direction due to the bias has a flexible curved portion that curves convexly outward in a direction perpendicular to the stacking direction of the battery cells.

[0008] According to the present invention, it is possible to prevent or suppress stress concentration at the tab connection portions between adjacent battery cells.

[0009] 1 is a schematic explanatory diagram of an all-solid-state battery that is one embodiment of a battery module according to one aspect of the present invention; FIG. 2 is an explanatory diagram of one embodiment of a battery cell that constitutes a battery module according to one aspect of the present invention, and the diagram shows a schematic cross-sectional view along the thickness direction of a cell that constitutes a laminated electrode body; FIG. 3 is an explanatory diagram of tab connections and tab leads between adjacent battery cells in a battery module according to one aspect of the present invention; FIG. 4 is a diagram (a) and (b) illustrating a state in which the tab connections and tab leads of FIG. 3 absorb displacement due to expansion and contraction of the battery cells during charge and discharge; FIG. 5 is a schematic diagram illustrating a state in which a flexible curved portion of the tab lead effectively absorbs displacement due to expansion and contraction of the cells during charge and discharge; FIG. 6 is an explanatory diagram (a), (b), and (c) illustrating modified tab connections and tab leads between adjacent battery cells in a battery module according to one aspect of the present invention; FIG. 7 is an explanatory diagram (a) and (b) illustrating modified tab connections and tab leads between adjacent battery cells in a battery module according to one aspect of the present invention; FIG. 8 is an explanatory diagram of modified tab connections and tab leads between adjacent battery cells in a battery module according to one aspect of the present invention; FIG. 10 is a schematic diagram illustrating an example of tab leads and tab connections between adjacent battery cells in a conventional battery module.

[0010] An all-solid-state battery according to one embodiment of the present invention will be described below with reference to the drawings as appropriate. The all-solid-state battery according to this embodiment is a secondary battery capable of being charged and discharged multiple times. It should be noted that the drawings are schematic. Therefore, it should be noted that the relationship between thickness and planar dimensions, ratios, etc., differ from the actual ones, and the drawings also include portions where the relationship between dimensions and ratios differ. Furthermore, the embodiments shown below exemplify devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention does not limit the materials, shapes, structures, arrangements, etc. of component parts to the following embodiments.

[0011] [Battery Module (All-Solid-State Battery)] As shown in Fig. 1 , the all-solid-state battery 100 of this embodiment includes a battery module 110 formed by stacking a plurality of battery cells 1. The battery module 110 is provided in a housing (not shown). One end of the battery module 110 is fixed to a base plate 104 in the stacking direction of the battery cells 1, and the other end is fixed to a movable plate 105. The base plate 104 and the movable plate 105 are interconnected by a plurality of guide rods 103 extending in the stacking direction of the battery cells 1. The stacked plurality of battery cells 1 are stacked between the base plate 104 and the movable plate 105, and are held in a pressurized state by elastic restraining bands or the like.

[0012] In the all-solid-state battery 100 of this embodiment, for example, four guide rods 103 are provided spaced apart around the periphery of the battery module 110 and support the movable plate 105 so that it can slide in the stacking direction of the battery cells 1. The base plate 104 is provided with a first connection terminal 101 that is electrically connected to an external device (not shown), and the movable plate 105 is provided with a second connection terminal 102 that is electrically connected to the external device. In the all-solid-state battery 100 of this embodiment, the base plate 104 is fixed to the housing, while the movable plate 105 has a sliding structure that follows the guide rods 103, and when the battery cells 1 expand and contract, the movable plate 105 can slide along the guide rods 103 in response to the expansion and contraction of the battery cells 1.

[0013] In the battery module 110 of this embodiment, the positive and negative electrode tab leads 31, 32 of each battery cell 1 are arranged to extend laterally from the center of one side and the other opposite side. In this embodiment, as will be described in detail later, the tab leads 31, 32 of adjacent battery cells 1 are connected to each other by welding or the like via flexible curved portions 40.

[0014] Furthermore, the positive electrode tab lead 31 and the negative electrode tab lead 32 located at both ends of the stacked battery cells 1 are disposed opposite the first connection terminal 101 and the second connection terminal 102, respectively, and are electrically connected to the first connection terminal 101 and the second connection terminal 102 via the flexible curved portion 40. In this way, in the battery module 110 of this embodiment, the positive electrode and negative electrode tab leads 31, 32 of adjacent battery cells 1 are connected to each other via the flexible curved portion 40, so that the entire plurality of battery cells 1, 1 are electrically connected in series.

[0015] [Battery Cell] Next, the structure of the battery cell 1 will be described with reference to Figure 2. The battery cell 1 of this embodiment is formed to have a substantially rectangular shape in a plan view. Note that the electrode structure of the battery cell 1 shown in the figure is a so-called non-bipolar type (internal parallel connection type), but it may also be a bipolar type (internal series connection type). Furthermore, the shape of the battery cell 1 is not limited to a rectangular shape, and may be a circular or elliptical shape, for example.

[0016] As shown in the figure, the battery cell 1 of this embodiment has a laminated electrode assembly 10 as a power generating element, which is made up of a positive electrode current collector 11, a positive electrode layer 13, a solid electrolyte layer 14, a negative electrode layer 15, and a negative electrode current collector 12 stacked one on top of the other. The laminated electrode assembly 10 is covered by a laminate film 20 including a pair of exterior bodies 21, 22 that sandwich and encase the laminated electrode assembly 10 from both sides in the thickness direction. The laminate film 20 has a metal foil layer and a resin layer. The laminate film 20 of this embodiment is integrally formed by sandwiching the metal foil layer between front and back resin layers.

[0017] The positive electrode current collector 11 and the negative electrode current collector 12 are formed in the shape of a rectangular thin plate from a metal material such as aluminum, nickel, iron, stainless steel, titanium, or copper. The positive electrode current collector 11 and the negative electrode current collector 12 each have a flexible lead electrode 11p, 12p extending laterally from one side forming the outer edge. Positive and negative electrode tab leads 31, 32 are attached to the tips of the lead electrodes 11p, 12p, respectively, as terminals.

[0018] The positive electrode layer 13 is disposed on both main surfaces of the positive electrode current collector 11 (at the end, only on the main surface of the positive electrode current collector 11 facing the negative electrode current collector 12). The positive electrode layer 13 is configured to contain, as a positive electrode active material, a substance that utilizes an oxidation-reduction reaction to release lithium ions during charging and to absorb lithium ions during discharging. Examples of materials for the positive electrode active material include lithium-transition metal composite oxides such as LiMn2O4, LiCoO2, LiNiO2, and Li(Ni-Mn-Co)O2, as well as lithium-transition metal phosphate compounds and lithium-transition metal sulfate compounds, such as those in which part of the transition metal in these oxides is substituted with other elements.

[0019] The solid electrolyte layer 14 contains a solid electrolyte as a main component and is a layer interposed between the positive electrode layer 13 and the negative electrode layer 15. Examples of solid electrolyte materials include sulfide solid electrolytes and oxide solid electrolytes, with sulfide solid electrolytes being preferred. Suitable sulfide solid electrolytes include LPS-based materials (e.g., argyrodite (LiPSCl)) and LGPS-based materials (e.g., LiGePSS).

[0020] The anode layer 15 is disposed on both main surfaces of the anode current collector 12 (only on the surface of the anode current collector 12 facing the cathode current collector 11 at the end). The anode layer 15 is configured to contain at least lithium metal or a substance that forms an alloy with lithium as anode active material. "Containing lithium metal as the anode active material in the anode layer 15" includes cases where lithium metal foil or lithium metal particles are disposed on the main surface of the anode current collector 12, and cases where lithium metal is deposited on the main surface of the anode current collector 12 using a cathode that includes a cathode active material such as a lithium-transition metal composite oxide, a lithium-transition metal phosphate compound, or a lithium-transition metal sulfate compound. "Containing a substance that forms an alloy with lithium as an active material in the anode layer 15" means that the anode layer 15 contains at least one substance selected from the group consisting of In, Al, Si, and Sn.

[0021] In this embodiment, as shown in Fig. 2 , the positive and negative electrode tab leads 31, 32 of each battery cell 1 are provided on the center line in the thickness direction of the battery cell 1, protruding laterally from one side and the other opposite side along the center line. The joint 23 of the exterior body 20 is sealed without gaps with an insulating sealant 50. Note that, as shown in Fig. 2 , in the following description, when there is no need to distinguish between the positive and negative electrode tab leads 31, 32, they will simply be referred to as tab leads 30.

[0022] [Tab Lead Connection Structure] Here, in the all-solid-state battery 100 of this embodiment, the negative electrode active material contains at least lithium metal or a material that forms an alloy with lithium, so that the stacked multiple battery cells 1, 1... expand and contract in the stacking direction as lithium ions are absorbed and released during charge and discharge. In contrast, in the all-solid-state battery 100 (battery module 110) of this embodiment, as shown in Figures 1 and 3 , the tab leads 31, 32 of the adjacent positive and negative electrodes of adjacent battery cells 1, 1 are connected to each other via flexible curved portions 40.

[0023] More specifically, in the all-solid-state battery 100 (battery module 110) of this embodiment, as shown in an enlarged view of a main part in FIG. 3 , among the plurality of stacked battery cells 1, adjacent battery cells 1, 1 in which positive and negative electrode tab leads 31, 32 are connected to each other are connected such that the tab connection portions 41, 42 between the adjacent battery cells 1, 1 are biased toward one of the battery cells 1, 1 (the side of the negative electrode tab lead 32 in the example shown in the same figure) with respect to the abutment surfaces 20m of the exterior bodies 20 of the adjacent battery cells 1, 1.

[0024] Furthermore, the tab connections 41, 42 of the tab leads 31, 32 are provided such that the mutual abutment surfaces 40m of the tab connections 41, 42 face the stacking direction of the battery cells 1 relative to the abutment surface 20m of the exterior body 20 (in the example shown in the figure, the direction parallel to the stacking direction). In the all-solid-state battery 100 (battery module 110) of this embodiment, the tab lead on the side with the longer distance in the stacking direction due to the bias (in the example shown in the figure, the positive electrode tab lead 31) is integrally formed as a flexible structure having a flexible curved portion 40 so as to connect to the extraction electrode of the laminated electrode body 10 inside the battery cell 1. Furthermore, the flexible curved portion 40 of this embodiment electrically connects the positive and negative electrode tab leads 31, 32 to each other while being curved convexly outward in a direction perpendicular to the stacking direction of the multiple battery cells 1. The tab leads 30 can be made of the same material and are a single flexible structure for the positive and negative electrodes. However, the tab leads 30 may be made of different materials for the positive and negative electrodes.

[0025] [Operational Effects] Next, the operational effects of the battery module 110 of this embodiment will be described. However, in a lithium deposition-type all-solid-state battery like the battery module 110 of this embodiment, when absorbing thickness changes of the battery cells 1 due to charge and discharge, there is a risk that a load greater than expected will be applied to the tab leads 31, 32 between adjacent battery cells 1, 1 and to the mutual tab connections 41, 42. For example, as in the conventional example shown in Figure 9, if adjacent battery cells 1000 are connected at their centers, stress may be concentrated on the tab connection 140.

[0026] In contrast, in the battery module 110 of this embodiment, as described above, the tab connection portions 41, 42 of the tab leads 31, 32 are biased to one side in the stacking direction with respect to the abutment surface 20m, and the tab lead 30 on the side opposite the tab connection portions 41, 42 is provided with a flexible curved portion 40 that curves convexly outward in a direction perpendicular to the stacking direction of the battery cells 1. As a result, with the battery module 110 of this embodiment, as shown in Figure 4, the tab connection portions 41, 42 are intentionally biased to one side with respect to the center in the stacking direction (the position of the abutment surface 20m of the exterior body 20), making them "asymmetrical," and the flexible curved portion 40 provided on the longer tab lead 30 can smoothly accommodate deformation during expansion and contraction.

[0027] That is, in the battery module 110 of this embodiment, the flexible bending portions 40 of the tab leads 31, 32 are asymmetrically curved so that the longer side in the stacking direction is convex outward in a direction perpendicular to the cell expansion direction. As a result, when transitioning from FIG. 4( a) to FIG. 4( b), the flexible bending portions 40 can effectively absorb the displacements (T, H) of the cells due to expansion and contraction during charging and discharging by expanding and contracting the curved shape of the flexible bending portions 40 in response to the displacement T in the stacking direction and the displacement H in the direction perpendicular to the stacking direction. Therefore, the battery module 110 of this embodiment reduces stress concentration on the tab connection portions 41, 42 and effectively absorbs the displacements due to expansion and contraction of the cells during charging and discharging. This reduces the stress applied to the tab leads 31, 32 and the tab connection portions 41, 42, effectively preventing or suppressing damage to the tab leads 31, 32 and the tab connection portions 41, 42 [Invention 1].

[0028] Furthermore, in the battery module 110 of this embodiment, as shown in FIG. 3 , the joint surfaces 40m of the tab connection portions 41, 42 face each other in the direction along the stacking direction of the battery cells 1, which is more suitable for mitigating stress acting on the tab leads 31, 32 and the tab connection portions 41, 42 in the cell expansion direction [Invention 2].

[0029] 3 , the tab lead 31 having the flexible bending portion 40 of the tab leads 31, 32 has a laminated structure in which multiple thin plates are stacked, so that stress caused by expansion and contraction during charge and discharge can be distributed to the laminated plates of the flexible bending portion 40. This further reduces stress applied to the tab leads 31, 32 and the tab connection portions 41, 42, which is more suitable for preventing breakage of the tab leads 31, 32 and the tab connection portions 41, 42. Furthermore, forming the flexible bending portion 40 into a laminated body increases the surface area, thereby further improving heat dissipation in the tab leads 31, 32 and the tab connection portions 41, 42 [Invention 3].

[0030] In other words, as shown in Figure 5, if the flexible bending section 40 has a curved structure (for example, radius r) made of a single plate (Figure 5(a)), when a stretching force P acts on the free end side and a displacement ω occurs, the bending rigidity increases as the cube of the plate thickness h. In contrast, as shown in Figure 5(b), by thinning the plate thickness to 1 / n, the bending rigidity can be reduced to 1 / n^3. Therefore, as shown in Figure 5(c) with an image of coil springs arranged in parallel, by making the flexible bending section 40 a laminate, flexibility can be increased even if the overall thickness is the same.

[0031] To ensure the same conductivity, electrical resistance, and heat resistance as a member with a plate thickness h as shown in Figure 1(a), the plate thickness must be the same as the plate thickness h shown in Figure 1(a). Therefore, in this embodiment, as shown in Figure 1(c), the flexible bending portion 40 is constructed by stacking n thin plates each having a thickness of (1 / n). When n thin plates, each having the thickness of a single plate divided by n, are stacked, the spring constant of the bending member is 1 / n^2, and the greater the number of divided plates, the greater the flexibility. Furthermore, by forming the flexible bending portion 40 as a laminate with an outwardly convex arc shape (e.g., radius r), it is possible to separate it from the battery cell 1 and increase the surface area of ​​the tab lead 30, thereby further improving the heat dissipation of the tab lead 30.

[0032] Furthermore, in the battery module 110 of this embodiment, in relation to the exterior body 20, as shown in Figure 3, the convex side of the flexible curved portion 40 protrudes laterally beyond the outer edge of the joint 23 of the exterior body 20 on the surface of the battery cell 1, which is advantageous in terms of spacing the flexible curved portion 40 away from the battery cell 1 and further improving heat dissipation [Invention 4].

[0033] As described above, the battery module 110 (all-solid-state battery 100) of this embodiment can prevent or suppress stress concentration on the tab connections 41, 42 between adjacent battery cells 1, 2. The battery module according to the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, in the battery module 110 of this embodiment, the flexible curved portion 40 may be provided with multiple curved portions that are convex outward. Furthermore, the flexible curved portion 40 may have a bellows shape with multiple curved portions connected together. With such a structure, the surface area of ​​the flexible curved portion 40 is increased, thereby further improving heat dissipation.

[0034] 6A and 6B show modified examples in which the positive and negative tab leads 31 and 32 in the battery module 110 of this embodiment can be made of the same material (e.g., aluminum alloy) (FIG. 6A). Also, for example, the positive and negative tab leads 31 and 32 in the battery module 110 of this embodiment can be made of different materials. For example, the positive and negative tab leads 31 and 32 can be made of aluminum alloy and copper alloy, respectively (FIG. 6B). Alternatively, the positive and negative tab leads 31 and 32 can be made of copper alloy and aluminum alloy, respectively (FIG. 6C). Furthermore, for example, in the battery module 110 of this embodiment, the positive electrode tab lead 31 and the negative electrode tab lead 32 are made of the same material as the current collectors 11, 12 inside the cell, which improves the bonding strength with the current collecting foil portion and is suitable for preventing or suppressing damage to the bonding portion when the battery cell 1 expands and contracts [Invention 5].

[0035] As shown in another modification in FIG. 7 , in the battery module 110 of this embodiment, the positive electrode tab lead 31 and the negative electrode tab lead 32 can have different lengths (i.e., lengths in the stacking direction, protrusion lengths in a direction intersecting the stacking direction, or a combination thereof). The degree of bias can also be increased or decreased. For example, the example in FIG. 7( a) shows an example in which the protrusion length (degree of convexity) of the flexible curved portion 40 in the direction intersecting the stacking direction is reduced. Also, FIG. 7( b) shows an example in which the protrusion length of the negative electrode tab lead 32 in the direction intersecting the stacking direction is increased, the degree of bias is reduced, and the length of the flexible curved portion 40 is shortened, so that the connection position of the tab connection portions 41, 42 is closer to the center in the stacking direction. This configuration increases the space available for forming the flexible bending portion 40 on the tab lead 30, making it easier to arrange the flexible bending portion 40 and tab connection portions 41, 42 regardless of the placement of the battery cell 1 or peripheral components. It also contributes to adjusting and reducing the spring constant of the tab lead 30, improving the stress reduction and breakage prevention effects of the tab lead 30 and tab connection portions 41, 42 even when the amount of expansion and contraction of the battery cell 1 increases [Invention 6].

[0036] 8 shows another modified example, in the battery module 110 of this embodiment, the tab connections 41, 42 that connect the positive electrode tab lead 31 and the negative electrode tab lead 32 to each other can be electrically connected by a connection means 43 such as crimping, laser welding, ultrasonic welding, or pressure contact. This configuration is suitable for electrically connecting adjacent battery cells 1 [Invention 7].

[0037] Furthermore, for example, in the battery module 100 of this embodiment, it is preferable to arrange the tab connections 41, 42 between the positive and negative tab leads 31, 32 on the battery cell 1 side using a material with a high melting point (materials can be selected as appropriate, such as aluminum alloy, stainless steel, or copper alloy). In other words, if a method of joining materials at high temperature is used as the connection means 43, focusing on the direction intersecting the stacking direction in FIG. 8 , for example, the inside of the cell can be protected by using a material with a higher melting point for the tab lead 32 on the battery cell 1 side than for the tab lead 31 on the opposite side from the battery cell 1 side. Therefore, this configuration is suitable for preventing or suppressing damage to the battery cell 1 when the tab connections 41, 42 are joined [Invention 8].

[0038] Furthermore, for example, in the battery module 100 of this embodiment, an example has been shown in which the flexible curved portion 40 is provided on the positive electrode side tab lead 31, but this is not limiting, and the flexible curved portion 40 can also be provided on the negative electrode side tab lead 32 by reversing the biasing side [Invention 9].

[0039] REFERENCE SIGNS LIST 1 Battery cell 10 Laminated electrode body 11 Positive electrode current collector 11p, 12p Lead electrode 12 Negative electrode current collector 13 Positive electrode layer 14 Solid electrolyte layer 15 Negative electrode layer 20 Laminate film (entire exterior body) 21, 22 Exterior body 23 Joint portion 30 Tab lead 31 Positive electrode side tab lead 32 Negative electrode side tab lead 40 Flexible curved portion 41, 42 Tab connection portion 50 Sealing material 100 All-solid-state battery 101 First connection terminal 102 Second connection terminal 103 Guide rod 104 Base plate 105 Movable plate 110 Battery module

Claims

1. A battery module comprising: a laminated electrode body formed by stacking a plurality of flat-shaped unit cells, each made by stacking a positive electrode, an electrolyte, and a negative electrode, in the thickness direction; a pair of exterior bodies that sandwich and encase the laminated electrode body from both sides in the thickness direction; and tab leads drawn out laterally from the joints between the pair of exterior bodies, the thickness of the laminated electrode body in the stacking direction changing with charging and discharging; and a plurality of the battery cells stacked in the stacking direction; wherein, of the plurality of stacked battery cells, adjacent battery cells, whose tab leads are connected to each other, have tab connection parts that connect the tab leads of adjacent battery cells connected at a position that is biased toward one of the battery cells with respect to the abutment surfaces of the exterior bodies of the adjacent battery cells; and further, the tab lead on the side that is farther apart in the stacking direction due to the bias has a flexible curved part that curves convexly outward in a direction perpendicular to the stacking direction of the battery cells.

2. The battery module according to claim 1, wherein the joining surfaces of the tab connections that connect the tab leads to one another face each other in a direction that follows the stacking direction of the battery cells.

3. The battery module according to claim 1, wherein the tab lead on the side having the flexible curved portion has a laminated structure in which a plurality of thin plates are superimposed.

4. The battery module according to claim 1, wherein the convex side of the flexible curved portion protrudes laterally beyond the outer edge of the joint of the exterior body.

5. The battery module according to claim 1, wherein the tab leads between the adjacent battery cells are made of different materials for the positive and negative tab leads.

6. The battery module according to claim 1, wherein the tab leads between the adjacent battery cells have different lengths for the positive and negative tab leads.

7. The battery module according to claim 1, wherein the tab connections that connect the tab leads of the adjacent battery cells are electrically connected to each other by caulking, laser welding, ultrasonic welding, or pressure contact.

8. The battery module according to claim 2, wherein the tab connection portion connecting the tab leads of the adjacent battery cells is made of a material with a higher melting point than the other tab lead, and the material is disposed on the battery cell side.

9. The battery module according to claim 1, wherein the tab lead having the flexible curved portion is a positive electrode tab lead.

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