Stacked battery

Abstract

To provide a stacked battery in which a current collecting tab and a terminal of each of a plurality of electrode bodies are properly bonded.SOLUTION: A stacked battery includes a plurality of electrode bodies 10A and 10B and a connection terminal 30. The electrode bodies 10A and 10B are formed in a plate shape and are laminated with the thickness direction as the stacking direction. The connection terminal electrically connects a first electrode body 10A and a second electrode body 10B laminated adjacent to each other. Each of the electrode bodies 10A and 10B includes a pair of current collecting tabs extending outward along the plate surface. One current collecting tab 11A in the first electrode body 10A and one current collecting tab 12B in the second electrode body 10B are joined to the connection terminal 30 from opposite directions in the stacking direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a stacked battery in which a plurality of electrode assemblies are stacked. [Background technology]

[0002] Batteries such as lithium-ion secondary batteries are widely used as portable power sources for personal computers, mobile terminals, and the like, or as power sources for driving vehicles such as EVs (electric vehicles), HVs (hybrid vehicles), and PHVs (plug-in hybrid vehicles). The battery includes an electrode body as a power generating element. The electrode body may be provided with a pair of current collecting tabs (a positive electrode current collecting tab and a negative electrode current collecting tab). Terminals are joined to the current collecting tabs. For example, in the electrode body of the battery disclosed in Patent Document 1, the pair of current collecting tabs extend in the same direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-24783 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a stacked battery in which multiple electrode bodies are stacked, it is necessary to electrically connect the multiple electrode bodies by joining the current collecting tabs of each of the multiple electrode bodies to a terminal. In conventional stacked batteries, unnecessary force is applied between the multiple current collecting tabs and the terminal, which can cause problems such as disengagement of the joints and damage to the foil that constitutes the electrode body. In addition, it is difficult to reduce the volume of the joints between the multiple current collecting tabs and the terminal, which can result in a decrease in the energy density of the stacked battery.

[0005] A typical object of the present invention is to provide a stacked battery in which the current collecting tabs and terminals of each of a plurality of electrode assemblies are appropriately joined. [Means for solving the problem]

[0006] In order to achieve this object, one embodiment of a stacked battery disclosed herein comprises a plurality of electrode bodies formed in a plate shape and stacked with the thickness direction as the stacking direction, and a connection terminal that electrically connects a first electrode body and a second electrode body that are stacked adjacent to each other, each of the first electrode body and the second electrode body having a pair of current collecting tabs extending outward along the plate surface, and one of the current collecting tabs in the first electrode body and one of the current collecting tabs in the second electrode body are joined to the connection terminal from opposite directions in the stacking direction.

[0007] The two current collecting tabs extending from each of the two stacked electrode bodies are offset in the stacking direction. Therefore, when the two current collecting tabs are joined to the connection terminal from the same direction in the stacking direction, it is necessary to join one current collecting tab in a state where it is bent more significantly than the other current collecting tab. Therefore, unnecessary force is easily applied to the joint portion, and it is difficult to reduce the volume of the joint portion. In contrast, in the stacked battery according to the present disclosure, the connection terminal is located between the two current collecting tabs. Therefore, when the connection terminal is viewed from a direction that intersects both the stacking direction of the multiple electrode bodies and the direction in which the current collecting tabs extend, the joint shape of each current collecting tab to the connection terminal is likely to be symmetrical. Therefore, unnecessary force is unlikely to be applied to the joint portion, and it is easy to reduce the volume of the joint portion.

[0008] In one advantageous aspect of the stacked battery disclosed herein, a pair of current collecting tabs extend from the electrode body in different directions. In this case, it is easier to increase the width of each current collecting tab to reduce resistance compared to when the pair of current collecting tabs extend in the same direction. In addition, it is easier to ensure a working space when joining the current collecting tabs to the connection terminals.

[0009] In one effective embodiment of the stacked battery disclosed herein, the electrode body has a rectangular plate shape, and a pair of current collecting tabs are provided on each of a pair of opposing side surfaces among the four side surfaces surrounding a pair of wide surfaces of the electrode body. In this case, alignment is easier when stacking a plurality of electrode bodies, compared to when the electrode body has a circular shape, etc. In addition, since the shape of the electrode body having a pair of current collecting tabs is close to rotational symmetry, the electrode body can be easily handled during manufacturing.

[0010] In one effective aspect of the stacked battery disclosed herein, when the longitudinal direction of the side surface on which the current collecting tabs are provided (i.e., the direction intersecting both the stacking direction of the multiple electrode bodies and the extending direction of the current collecting tabs) is taken as the width direction of the electrode bodies, the positions of a pair of current collecting tabs in the width direction are different from each other. In this case, by stacking two identical electrode bodies with one of them turned upside down, the positive electrode current collecting tab and the negative electrode current collecting tab are joined to the connection terminal on one side, and the positions of the positive electrode current collecting tab and the negative electrode current collecting tab on the opposite side are different in the width direction. Thus, the first electrode body and the second electrode body, which are the same electrode body, are appropriately connected in series.

[0011] In one advantageous aspect of the stacked battery disclosed herein, the material of the connection terminal is the same as the material of at least one of the pair of current collecting tabs, in which case at least one of the pair of current collecting tabs is joined to the connection terminal with higher strength.

[0012] In one effective aspect of the laminated battery disclosed herein, the connection terminal is a joining member formed by joining one material of a pair of current collecting tabs to the other material. In this case, each of the pair of current collecting tabs is joined to the connection terminal with high strength. The specific aspect of the connection terminal, which is the joining member, can be appropriately selected. For example, a clad material formed by joining metals of different materials by stretching them under pressure may be used as the connection terminal. Also, a joining member formed by joining metals of different materials by ultrasonic joining, resistance welding, laser welding, fastening, or the like may be used as the connection terminal. In this case, the joining of the multiple metals may be performed in advance before the current collecting tabs are joined to the connection terminal. Also, the multiple metals may be joined after the current collecting tabs are joined to each metal. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a plan view of the stacked battery 1 with the exterior body 5 and holder 40 omitted. [Diagram 2] 2 is an exploded perspective view of a first electrode body 10A, a second electrode body 10B, an insulating member 7, and a connection terminal 30. FIG. [Diagram 3] 1. FIG. 1 is a view of the joint portion between the current collecting tabs 11A, 12B and the connection terminal 30 as viewed from the width direction (from below in FIG. 1). [Figure 4] 1. FIG. 1 is a view of the joint portion between the current collecting tabs 11A, 12B and the connection terminal 30 as viewed from the extension direction (the right side in FIG. 1). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, one of the typical embodiments of the present disclosure will be described in detail with reference to the drawings. Matters other than those specifically mentioned in this specification and necessary for implementation can be understood as design matters of a person skilled in the art based on the prior art in the field. The present invention can be implemented based on the contents disclosed in this specification and the technical common sense in the field. In the following drawings, members and parts that perform the same function are described with the same reference numerals. In addition, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect the actual dimensional relationships.

[0015] In this specification, the term "battery" refers to a general storage device capable of extracting electric energy, and is a concept that includes primary batteries and secondary batteries. "Secondary battery" refers to a general storage device that can be repeatedly charged and discharged, and includes so-called storage batteries (i.e., chemical batteries) such as lithium ion secondary batteries, nickel metal hydride batteries, and nickel cadmium batteries, as well as capacitors (i.e., physical batteries) such as electric double layer capacitors.

[0016] The configuration of the stacked battery 1 of this embodiment will be described with reference to Figures 1 and 2. The depth direction of the paper in Figures 1 and 2 is the stacking direction of the electrode body 10 (i.e., the thickness direction of the electrode body 10). The up-down direction of the paper in Figure 1 is the width direction of the stacked battery 1 and the electrode body 10. The left-right direction of the paper in Figure 1 is the extension direction of the stacked battery 1 and the electrode body 10.

[0017] The stacked battery 1 of this embodiment includes an exterior body 5, a plurality of electrode assemblies 10 (a first electrode body 10A and a second electrode body 10B), external terminals 21, 22 (a positive electrode external terminal 21 and a negative electrode external terminal 22), a connection terminal 30, and a holder 40. In Fig. 1, the exterior body 5 is indicated by a dotted line covering the periphery of the electrode assemblies 10, etc. Also, in Fig. 1, the holder 40 is indicated by a dotted line covering a joint portion including the connection terminal 30.

[0018] The exterior body 5 accommodates the electrode body 10 and the like inside. As an example, a laminate film having appropriate flexibility is used for the exterior body 5 of this embodiment. However, it is also possible to change the material of the exterior body 5. For example, an exterior body made of metal or resin having appropriate rigidity may be used.

[0019] The electrode body 10 is a power generating element in the stacked battery 1. The stacked battery 1 is preferably a secondary battery having a high energy density among various batteries. The stacked battery 1 of this embodiment is a lithium ion battery, which is an example of a particularly suitable secondary battery. However, the stacked battery 1 may be a secondary battery other than a lithium ion battery (e.g., a nickel-metal hydride battery). The stacked battery 1 of this embodiment is an all-solid-state battery in which the electrolytic solution is replaced with a solid electrolyte. However, the stacked battery 1 does not have to be an all-solid-state battery, and the electrolytic solution may be accommodated inside the exterior body 5.

[0020] In the electrode body 10 of this embodiment, a positive electrode collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode collector layer are laminated in this order. Any collector layer can be used as the positive electrode collector layer and the negative electrode collector layer. For example, collector layers of various metals such as silver, copper, gold, aluminum, nickel, iron, stainless steel, or titanium can be used. The positive electrode active material layer includes a positive electrode active material, and optionally a conductive assistant, a binder, and solid electrolyte particles. Examples of the positive electrode active material include at least one transition metal selected from manganese, cobalt, nickel, and titanium, and a metal oxide containing lithium (for example, lithium cobalt oxide, lithium nickel oxide, and lithium nickel cobalt manganese oxide, etc.). For the solid electrolyte layer, a material that can be used as a solid electrolyte for an all-solid-state battery can be used. For example, sulfide-based amorphous solid electrolyte particles such as 8Li2O 67Li2S 25P2S5, Li2S, P2S5, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, or LiI-Li2S-B2S3, oxide-based amorphous solid electrolyte particles such as Li2O-B2O3-P2O5, or Li2O-SiO2, or Li 1.3 Al 0.3Ti 0.7 (PO4)3 or Li 1+x+y A x Ti 2-x Si y P 3-y O 12 (A is Al or Ga, 0 ≦ x ≦ 0.4, 0 < y ≦ 0.6), etc., crystalline oxides can be used. The negative electrode active material layer includes a negative electrode active material, and optionally a conductive assistant, a binder, and solid electrolyte particles. The negative electrode active material is not particularly limited as long as it can occlude and release metal ions such as lithium ions.

[0021] As shown in FIG. 2, the outer shape of the electrode body 10 is formed in a plate shape. Specifically, the shape of the electrode body 10 of the present embodiment is a rectangular plate shape with the width direction as the short side direction, and has a pair of wide surfaces 15 and four side surfaces 16A and 16B surrounding the periphery of the wide surface. In the laminated battery 1, a plurality of electrode bodies 10 are laminated in the thickness direction. Specifically, the plurality of electrode bodies 10 are laminated in a state where the wide surfaces 15 of two adjacent electrode bodies 10 are aligned. As an example, in the laminated battery 1 of the present embodiment, two electrode bodies 10 (the first electrode body 10A and the second electrode body 10B) are laminated. However, the number of electrode bodies 10 to be laminated may be three or more. Further, in the present embodiment, the same electrode body 10 is laminated and mounted on the laminated battery 1. Therefore, compared with the case where different electrode bodies are separately manufactured and laminated, the manufacturing process of the laminated battery 1 is simplified.

[0022] Note that in the present embodiment, an insulating member 7 (see FIG. 2) for preventing short circuit is disposed between two adjacent electrode bodies 10 (in the present embodiment, between the first electrode body 10A and the second electrode body 10B). However, when an insulating layer is provided in advance on the surface of the electrode body 10, etc., it is also possible to omit the insulating member 7.

[0023] 2, each of the multiple electrode bodies 10 includes a pair (two) of current collecting tabs. The pair of current collecting tabs extends outward along the plate surface of the electrode body 10. In detail, the first electrode body 10A includes a positive electrode current collecting tab 11A and a negative electrode current collecting tab 12A. The second electrode body 10B includes a positive electrode current collecting tab 11B and a negative electrode current collecting tab 12B.

[0024] In this embodiment, the pair of current collecting tabs extend from the electrode body 10 in different directions. If the pair of current collecting tabs extend from the electrode body 10 in the same direction (for example, in parallel) the pair of current collecting tabs must be installed on the same edge (same side surface 16) of the plate-shaped electrode body 10. In this case, in order to prevent two current collecting tabs provided on the same electrode body 10 from being electrically connected, it is necessary to limit the width of each current collecting tab. In contrast, by extending the pair of current collecting tabs from the electrode body 10 in different directions, it becomes easy to increase the width of each current collecting tab and reduce the resistance. In addition, since the positions of each current collecting tab are spaced apart, it is easy to secure space when performing a joining operation, etc., which will be described later.

[0025] More specifically, the pair of current collecting tabs are provided on each of a pair of opposing side surfaces among the four side surfaces (each of the four side surfaces 16A of the first electrode body 10A and each of the four side surfaces 16B of the second electrode body 10B) surrounding the pair of wide surfaces 15A, 15B of the electrode body 10. In other words, the pair of current collecting tabs extend in directions diametrically opposite to each other. Therefore, the shape of the electrode body 10 including the pair of current collecting tabs is close to rotationally symmetric. Therefore, the electrode body 10 can be easily handled when manufacturing the stacked battery 1.

[0026] The longitudinal direction of the side surface on which the current collecting tab is provided (i.e., the direction intersecting both the stacking direction of the multiple electrode bodies and the extension direction of the current collecting tab) is defined as the width direction. In this case, the positions of the pair of current collecting tabs in the width direction are different from each other. For example, in the state shown in FIG. 2, the positive electrode current collecting tab 11A of the first electrode body 10A is located below the center of the width direction of the side surface of the first electrode body 10A on the paper, whereas the negative electrode current collecting tab 12A is located above the center of the width direction of the side surface of the first electrode body 10A on the paper. As a result, the first electrode body 10A and the second electrode body 10B are appropriately connected in series, which will be described in detail later.

[0027] The connection terminal 30 electrically connects the first electrode body 10A and the second electrode body 10B that are stacked adjacent to each other. As an example, in the stacked battery 1 of this embodiment, the first electrode body 10A and the second electrode body 10B are connected in series. In detail, in this embodiment, the positive electrode current collector tab 11A of the first electrode body 10A and the negative electrode current collector tab 12B of the second electrode body 10B are electrically connected by the connection terminal 30, so that the first electrode body 10A and the second electrode body 10B are connected in series. However, the joining structure of the connection terminal 30 and the current collector tabs exemplified in this embodiment (details will be described later) may be used when connecting the first electrode body 10A and the second electrode body 10B in parallel. In other words, the technology exemplified in this embodiment can also be applied to the case where two positive electrode current collector tabs 11A, 11B are connected to a connection terminal, and the case where two negative electrode current collector tabs 12A, 12B are connected to a connection terminal.

[0028] The external terminals 21, 22 electrically connect the stacked battery 1 to the outside. As an example, in this embodiment, the positive electrode external terminal 21 is joined to the positive electrode current collector tab 11B of the second electrode body 10B, and the negative electrode external terminal 22 is joined to the negative electrode current collector tab 12A of the first electrode body 10A, among the first electrode body 10A and the second electrode body 10B connected in series. As shown in FIG. 1, the exterior body 5 accommodates the electrode body 10 and the like inside with the external terminals 21, 22 protruding outward. In this embodiment, the electrode body 10 and the like are sealed inside the exterior body 5 with tab seals 25 for sealing gaps provided between the external terminals 21, 22 and the exterior body 5.

[0029] The holder 40 (see FIG. 1) ensures insulation by covering the pair of joined current collecting tabs 11A, 12B and the connection terminal 30. The holder 40 may be formed of, for example, a material (such as resin) having insulation properties and appropriate rigidity.

[0030] The joining structure of the connection terminal 30 and the current collecting tabs 11A, 12B in this embodiment will be described in detail below. Fig. 3 is a view of the joining portion between the current collecting tabs 11A, 12B and the connection terminal 30 as viewed from the width direction (lower side in Fig. 1). Fig. 4 is a view of the joining portion between the current collecting tabs 11A, 12B and the connection terminal 30 as viewed from the extension direction (right side in Fig. 1).

[0031] 3 and 4, in the stacked battery 1 of this embodiment, one current collecting tab of the first electrode body 10A (positive electrode current collecting tab 11A in this embodiment) and one current collecting tab of the second electrode body 10B (negative electrode current collecting tab 12B in this embodiment) are joined to the connection terminal 30 from opposite directions in the stacking direction. That is, in the example shown in FIGS. 3 and 4, the positive electrode current collecting tab 11A is joined to the connection terminal 30 from above in the figure, whereas the negative electrode current collecting tab 12B is joined to the connection terminal 30 from below in the figure. Note that, for example, at least one of ultrasonic welding, resistance welding, laser welding, etc. can be used as a method for joining the current collecting tabs 11A, 12B to the connection terminal 30.

[0032] As shown in FIG. 3, the two current collecting tabs 11A, 12B extending from each of the two stacked electrode bodies 10A, 10B are shifted in the stacking direction. Therefore, when the two current collecting tabs 11A, 12B are joined to the connection terminal 30 from the same direction in the stacking direction, it is necessary to join one of the current collecting tabs in a state where it is bent more significantly than the other current collecting tab. In this case, unnecessary force is likely to be applied to the joint portion, and it is also difficult to reduce the volume of the joint portion. In contrast, in the stacked battery 1 of this embodiment, the connection terminal 30 is located between the two current collecting tabs 11A, 12B. Therefore, as shown in FIG. 3, when the connection terminal 30 is viewed from the width direction, the joint shape of each of the current collecting tabs 11A, 12B to the connection terminal 30 tends to be symmetrical (vertically symmetrical in FIG. 3). Therefore, unnecessary force is unlikely to be applied to the joint portion, and it is easy to reduce the volume of the joint portion. Furthermore, in this embodiment, the structure of the holder 40 (see FIG. 1) attached to the joint portion is also simplified.

[0033] In this embodiment, the material of the positive electrode current collector tabs 11A, 11B is different from the material of the negative electrode current collector tabs 12A, 12B. Here, if the material of the current collector tabs is different from the material of the connection terminal, the bonding strength may be reduced. However, the connection terminal 30 of this embodiment is a bonding member in which one material of the two current collector tabs 11A, 12B is bonded to the other material. In detail, the connection terminal 30 of this embodiment is a clad material in which a metal 31A made of the same material as the positive electrode current collector tabs 11A, 11B and a metal 31B made of the same material as the negative electrode current collector tabs 12A, 12B are bonded by stretching them under pressure. Therefore, the positive electrode current collector tab 11A is bonded to the metal 31A, and the negative electrode current collector tab 12B is bonded to the metal 31B, so that both of the two current collector tabs 11A, 12B are bonded to the connection terminal 30 with high strength.

[0034] As shown in Fig. 2, in the electrode body 10 (each of the first electrode body 10A and the second electrode body 10B) of this embodiment, the positions of a pair of current collector tabs in the width direction are different from each other. Therefore, by stacking two identical electrode bodies 10 with one side turned upside down, the positive electrode current collector tab 11A and the negative electrode current collector tab 12B are joined to the connection terminal 30 on one side (the right side in Fig. 2), and the positions of the positive electrode current collector tab 11B and the negative electrode current collector tab 12A on the opposite side (the left side in Fig. 2) in the width direction are different. Therefore, the first electrode body 10A and the second electrode body 10B, which are the same electrode body 10, are appropriately connected in series.

[0035] The technology disclosed in the above embodiment is merely an example. Therefore, the technology exemplified in the above embodiment can be modified. For example, in the stacked battery 1 of the above embodiment, two electrode bodies 10 are stacked. However, the technology exemplified in the present disclosure can also be applied to a stacked battery in which three or more electrode bodies are stacked. In this case, the technology exemplified in the present disclosure may be adopted when electrically connecting at least one of two or more sets of electrode bodies adjacent to each other.

[0036] The connection terminal 30 in the above embodiment is a joining member in which one material of the two current collector tabs 11A, 12B is joined to the other material. However, the configuration of the connection terminal can be changed. For example, the material of the connection terminal may be the same as the material of one of the positive current collector tabs 11A, 11B and the negative current collector tabs 12A, 12B. In this case, one of the positive current collector tabs 11A, 11B and the negative current collector tabs 12A, 12B is joined to the connection terminal with high strength, and the configuration of the connection terminal is simplified. In addition, when the material of the positive current collector tabs 11A, 11B and the material of the negative current collector tabs 12A, 12B are the same, the material of the connection terminal may be the same as the material of the positive current collector tabs 11A, 11B and the negative current collector tabs 12A, 12B. In this case, both of the two current collector tabs are joined to the connection terminal with high strength. [Explanation of symbols]

[0037] 1. Stacked battery 10A,10B electrode body 11A, 11B Positive electrode current collecting tab 12A, 12B Negative electrode current collecting tab 15A, 15B Wide surface 16A,16B side 30 Connection terminal

Claims

1. A plurality of electrode bodies formed in a plate shape and stacked with a thickness direction as a stacking direction, the first electrode body and the second electrode body being stacked adjacent to each other; a connection terminal that electrically connects the first electrode body and the second electrode body to each other; an exterior body that houses all of the electrode assemblies therein; Equipped with each of the first electrode body and the second electrode body includes a positive electrode current collecting tab and a negative electrode current collecting tab extending outside the electrode body along a plate surface inside the one exterior body, the positive electrode current collecting tab and the negative electrode current collecting tab extending in mutually different directions from the electrode body; the electrode body has a rectangular plate shape, the positive electrode current collecting tab and the negative electrode current collecting tab are provided separately on each of a pair of mutually opposing side surfaces among four side surfaces surrounding a pair of wide surfaces of the electrode body, When a longitudinal direction of the side surface on which the positive electrode current collecting tab and the negative electrode current collecting tab are provided is defined as a width direction of the electrode body, the positions of the positive electrode current collecting tab and the negative electrode current collecting tab in the width direction are different from each other, a positive electrode current collecting tab of the first electrode body and a negative electrode current collecting tab of the second electrode body are joined to the connection terminals from opposite directions in the stacking direction inside the single outer casing.

2. 2. The stacked battery according to claim 1, wherein the material of the connection terminal is the same as the material of at least one of the positive electrode current collector tab and the negative electrode current collector tab.

3. 2. The stacked battery according to claim 1, wherein the connection terminal is a joining member formed by joining one material of the positive electrode current collector tab and the negative electrode current collector tab to the other material.

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