JP7144489B2 - storage module - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to an electric storage module, a welding method, and a method for manufacturing an electric storage module using the same.

Patent Document 1 describes end plates arranged on both end surfaces of a battery laminate in which secondary battery cells and separators are alternately laminated, a fastening member for fastening the end plates together, and an intermediate portion of the laminate. A structure is disclosed that includes an intermediate bracket that

WO2017/017913

As the capacity of power storage devices such as secondary batteries increases, the number of cells tends to increase, and modules tend to elongate in the direction in which the cells are arranged. As a result, when the storage cell is displaced, there is a portion where the force acting on the busbar joint becomes large. Even under such circumstances, it is necessary to prevent damage to the busbar joints.

On the other hand, excessive enlargement and excessive design of the busbar joints lead to an increase in the size and manufacturing cost of the power storage module as a whole.

An object of the present disclosure is to provide a power storage module capable of preventing breakage of busbar joints while suppressing excessive upsizing and excessive design, a welding method, and a method of manufacturing a power storage module using the same. be.

A power storage module according to the present disclosure includes a plurality of power storage cells stacked along an arrangement direction and constrained along the arrangement direction, and a plurality of bus bars electrically connecting the plurality of power storage cells.

In one aspect, the plurality of bus bars are respectively provided at first positions and second positions where different loads act when the plurality of storage cells are displaced along a direction intersecting the arrangement direction. a first bus bar and a second bus bar, wherein the plurality of storage cells includes first terminals and second terminals respectively joined to the first bus bar and the second bus bar by welding; The welding strength between the first bus bar and the first terminal and the welding strength between the second bus bar and the second terminal differ from each other corresponding to the difference in .

In another aspect, the bus bar further includes a fixing portion for fixing some of the plurality of power storage cells, and the plurality of bus bars are arranged at first positions and first positions at different distances from the fixing portion along the arrangement direction. a first bus bar and a second bus bar respectively provided at two positions; the plurality of power storage cells including a first terminal and a second terminal respectively joined to the first bus bar and the second bus bar by welding; The welding strength between the busbar and the first terminal and the welding strength between the second busbar and the second terminal are different from each other.

A welding method according to the present disclosure is a welding method for welding a plurality of electrode terminals of a plurality of storage cells stacked along the arrangement direction and a plurality of bus bars, wherein the plurality of electrode terminals are arranged along the arrangement direction. The plurality of busbars includes a first terminal and a second terminal respectively arranged at a first position and a second position at different positions, and the plurality of busbars are joined by welding to the first terminal and the second terminal, respectively. and a second bus bar, and the welding method includes welding the first bus bar and the first terminal using a first method, and welding the second bus bar using a second method different from the first method and welding the second terminal.

A method for manufacturing an energy storage module according to the present disclosure includes a step of stacking a plurality of energy storage cells including a plurality of electrode terminals along an arrangement direction, a step of arranging a plurality of bus bars on the plurality of electrode terminals, and welding the plurality of electrode terminals and the plurality of bus bars using the method.

According to the present disclosure, it is possible to provide a power storage module capable of preventing breakage of busbar joints while suppressing excessive upsizing and excessive design, a welding method, and a method of manufacturing a power storage module using the same. can.

It is a figure which shows the basic composition of an assembled battery. FIG. 2 is a diagram showing a battery cell in the assembled battery shown in FIG. 1; FIG. 2 is a diagram showing the arrangement of busbars in the assembled battery shown in FIG. 1; It is a figure which shows an example of a bus-bar shape. FIG. 10 is a diagram showing another example of busbar shape; FIG. 9 is a diagram showing still another example of busbar shape; FIG. 9 is a diagram showing still another example of busbar shape;

Embodiments of the present disclosure will be described below. In the embodiments described below, when referring to the number, amount, etc., the scope of the present disclosure is not necessarily limited to the number, amount, etc., unless otherwise specified. Also, in the following embodiments, each component is not necessarily essential for the present disclosure unless otherwise specified.

FIG. 1 is a diagram showing the basic configuration of an assembled battery 1. As shown in FIG. FIG. 2 is a diagram showing a battery cell 100 in the assembled battery 1. As shown in FIG.

As shown in FIGS. 1 and 2 , an assembled battery 1 as an example of a “storage module” includes battery cells 100 and binding members 200 . A plurality of battery cells 100 are provided so as to line up in the direction of arrow DR1 (arrangement direction). Battery cell 100 includes an electrode terminal 110 . A separator (not shown) is interposed between the plurality of battery cells 100 .

As an example, the battery cell 100 is a lithium ion battery, but the battery cell 100 may be another battery such as a nickel metal hydride battery. Further, in the present disclosure, the "storage module" is not limited to the assembled battery 1, and instead of the battery cells 100, for example, a capacitor may be used as the "storage cell".

The restraining member 200 includes end plates 210 and fastening members 220 . The end plates 210 are arranged at both ends of the assembled battery 1 in the arrow DR1 direction (arrangement direction). The end plate 210 is fixed to a base such as a case that houses the assembled battery 1 . The fastening member 220 connects the two end plates 210 positioned at both ends of the assembled battery 1 in the arrangement direction and constrains the two end plates 210 .

A plurality of battery cells 100 sandwiched between the two end plates 210 are pressed by the end plates 210 and constrained between the two end plates 210 .

As shown in FIG. 2, the battery cell 100 is formed in a flat rectangular parallelepiped shape. Electrode terminal 110 includes a positive terminal 111 and a negative terminal 112 . The electrode terminal 110 is formed on the housing case 120 . The accommodation case 120 accommodates an electrode assembly and an electrolytic solution (not shown).

FIG. 3 is a diagram showing the arrangement of busbars in the assembled battery 1. As shown in FIG. The example shown in FIG. 3 connects a plurality of battery cells 100 in series. That is, in the example of FIG. 3 , the positive terminal 111 and the negative terminal 112 of adjacent battery cells 100 are electrically connected by bus bars 310 , 320 , 330 .

As used herein, the term "bus bar" means a member that electrically connects electrode terminals of two or more battery cells. Although the example of FIG. 3 shows a structure in which the battery cells 100 are connected in series, the scope of the present disclosure is not limited to this, and includes a structure in which the battery cells 100 are connected in parallel.

Electrode terminal 110 and busbars 310, 320, 330 are typically joined by welding. Electrode terminal 110 is made of copper, for example. The busbars 310, 320, 330 may be made of aluminum (aluminum busbar), or have higher rigidity than the aluminum busbar and have a clad layer made of copper on the surface of the aluminum member (clad busbar). may be When the electrode terminal 110 is made of copper, dissimilar materials are joined (welded) when an aluminum bus bar is used, and similar materials are joined (welded) when a clad bus bar is used.

The battery cells 100 positioned at both ends of the assembled battery 1 in the direction of the arrow DR1 (arrangement direction) are directly fixed by end plates 210 as "restraining portions". When an external load acts on the battery module including the assembled battery 1, the load acting on the bus bar 310 (first bus bar) connecting the electrode terminals 110 of the two adjacent battery cells 100 in the relevant portion, and the bus bar 310 and the electrode terminal 110 The load acting on the junction with is relatively large.

On the other hand, the battery cell 100 located in the central portion of the assembled battery 1 in the direction of the arrow DR1 (arrangement direction) is located away from the end plate 210 as the "restraining portion". When an external load acts on the battery module including the assembled battery 1, the load acting on the bus bar 320 (second bus bar) connecting the electrode terminals 110 of the two adjacent battery cells 100 in the relevant portion, and the bus bar 320 and the electrode terminal 110 The load acting on the junction with is relatively small.

With the demand for higher output of battery modules, the number of battery cells 100 constituting the assembled battery 1 has increased, and the assembled battery 1 tends to become longer along the direction in which the battery cells 100 are arranged (the direction of the arrow DR1). . As a result, the difference in load acting on bus bar 310 (first bus bar) and bus bar 320 (second bus bar) when an external load acts tends to increase.

As described above, when an external load acts on assembled battery 1 , the load acting on bus bar 310 and the load acting on the junction between bus bar 310 and electrode terminal 110 are large. Therefore, bus bar 310 can be prevented from being damaged by making bus bar 310 into a shape that can easily absorb deformation, or bus bar 310 can be prevented from being damaged by increasing the rigidity of bus bar 310 so that bus bar 310 can withstand a large load. Prevention is required. Similarly, it is required to increase the welding strength at the junction between bus bar 310 and electrode terminal 110 so that the junction can withstand a large load.

On the other hand, the load acting on bus bar 320 and the load acting on the junction between bus bar 320 and electrode terminal 110 are small. Therefore, when bus bar 320 is formed with the same specifications as bus bar 310, bus bar 320 becomes larger than necessary. Further, if the joints between the busbar 320 and the electrode terminals 110 are formed with the same specifications as the joints between the busbars 310 and the electrode terminals 110, the welded joints are formed with excessively high welding strength, resulting in undesirable results. Increases required manufacturing costs.

In this way, if the busbars 310, 320, and 330 are uniformly the same under conditions where the load conditions differ along the array direction of the battery cells 100 (the direction of the arrow DR1), the size of the busbars increases even at unnecessary locations. At the same time, there may be a portion of the welded portion that is excessively designed to have an unnecessarily high weld strength.

On the other hand, in the present embodiment, as a first solution, the shapes of the busbars are made different from each other according to the load state when the external load is applied.

More specifically, busbar 310 (first busbar) and busbar 320 (second busbar), which are located at different distances from end plate 210, have different shapes. In other words, the busbars 310 (first busbar) and the busbars 320 (second busbar), which are subjected to different loads when the battery cells 100 are displaced from each other and the assembled battery 1 is deformed, have different shapes. do.

For example, bus bar 310 near end plate 210 serving as a “restraining portion” has a shape that easily absorbs deformation, thereby reducing stress when an external load acts. On the other hand, bus bar 320, which is far from end plate 210, does not have an excessively large stress when an external load is applied, even if it has a shape that is relatively difficult to absorb deformation.

Further, bus bar 310 near end plate 210 may be configured to have relatively high rigidity to prevent breakage when an external load acts. At this time, bus bar 320 far from end plate 210 is configured to have a simpler structure than bus bar 310 so as to prevent over-design.

Differentiating the shapes of busbars 310 and 320 includes differentiating the plane shapes of the busbars viewed from the direction of arrow DR2, differentiating the shape of the side surfaces of the busbars viewed from the direction of arrow DR3, and varying the shapes of both of them. . Making the busbar plane shapes different as seen from the direction of arrow DR2 simply involves making the widths of busbars 310 and 320 different, and making the busbar side shapes different as seen from the direction of arrow DR3 simply makes the thicknesses of busbars 310 and 320 different. different.

Further, in the present embodiment, as a second solution different from the above first solution, the welding strength of bus bar 310 and electrode terminal 110 and the welding strength of bus bar 320 and electrode terminal 110 are adjusted according to the load state when an external load is applied. The welding strengths of the terminals 110 are made different from each other.

More specifically, bus bar 310 (first bus bar) and bus bar 320 (second bus bar) having different distances from end plate 210 have different welding strengths at joints with electrode terminals 110 of battery cell 100. . In other words, the busbars 310 (first busbars) and busbars 320 are subjected to different loads when the battery cells 100 are displaced along the direction intersecting the arrangement direction (the direction of the arrow DR1) and the assembled battery 1 is deformed. (Second bus bar), the welding strength of the junction between the battery cell 100 and the electrode terminal 110 is made different from each other.

For example, bus bar 310 near end plate 210 as a “restraining portion” is welded to electrode terminal 110 with a high welding strength so that it can withstand a relatively high external load. On the other hand, for bus bar 320 far from end plate 210, even if the welding strength with electrode terminal 110 is not particularly increased, the load acting on the welded portion will not become excessively large when an external load acts. Therefore, bus bar 320 is configured to have a simpler welded structure than bus bar 310 so as to prevent over-design.

The first solution (differentiating the shape of the busbars) and the second solution (differentiating the welding strength to the electrode terminals) described above can be applied independently to the assembled battery 1. However, a combination of the first solution and the second solution may be applied to the assembled battery 1 .

In addition, as shown in FIG. 3 , a bus bar 330 (third bus bar) is provided between the bus bar 310 and the bus bar 320 . Bus bar 330 has intermediate characteristics between bus bar 310 and bus bar 320 in terms of its shape and welding strength with electrode terminal 110 . Thus, in the example of FIG. 3, the shape of the busbar and the characteristics of the joint change in three stages. You may change the characteristics to However, in the case of four or more stages, the number of parts increases and the welding process becomes complicated, which may increase the manufacturing cost. Therefore, it is preferable to use two or three stages.

Busbars that can be used for the first and second solutions described above will now be described with reference to FIGS.

FIG. 4 shows a busbar 310A as an example of the busbar 310. As shown in FIG. FIG. 5 shows a busbar 320A as an example of the busbar 320. As shown in FIG.

Bus bar 310A includes welded portion 311A with electrode terminal 110, projecting portion 312A, and connection portion 313A connecting welded portion 311A and projecting portion 312A. Bus bar 320A includes welded portion 321A with electrode terminal 110 and intermediate portion 322A positioned between two welded portions 321A.

Projecting portion 312A projects from welding portion 311A in a direction orthogonal to DR1 direction (arrangement direction) when viewed from arrow DR2 direction (the direction in which bus bar 310A and electrode terminal 110 overlap), that is, along arrow DR3 direction. It is formed. The protruding portion 312A may protrude outward in the width direction of the assembled battery 1 (battery cell 100), or may protrude inward in the width direction of the assembled battery 1 (battery cell 100).

As shown in FIG. 4, the busbar 310A has a substantially U-shaped shape. As a result, compared with the rectangular bus bar 320A, the effective length is longer and the deformation can be easily absorbed. Therefore, stress when an external load acts is reduced, and damage to bus bar 310A to which a relatively large load acts is prevented.

In this specification, the term “effective length” means the length of the busbar extending along the extending direction of the busbar between two joints between the busbar and the storage cell.

FIG. 6 shows a busbar 310B as another example of busbar 310. As shown in FIG. Bus bar 310B includes welded portion 311B with electrode terminal 110, projecting portion 312B, and connection portion 313B connecting welded portion 311B and projecting portion 312B.

Projection portion 312B extends from welding portion 311B along the direction perpendicular to the direction DR1 (arrangement direction) when viewed from the direction of arrow DR3 (the direction perpendicular to the direction in which busbar 310B and electrode terminal 110 overlap), that is, along the direction of arrow DR2. formed to protrude.

Similarly to the bus bar 310A shown in FIG. 4, the bus bar 310B shown in FIG. 6 also has a substantially U-shaped shape. Easy to absorb. Therefore, stress when an external load acts is reduced, and damage to bus bar 310B to which a relatively large load acts is prevented.

As an example, the effective length of busbar 310 , which receives a relatively large load when an external load acts, is preferably about 1 to 10 times the effective length of busbar 320 .

As an example, the thickness of bus bar 310 is preferably about 0.5 to 5 times the thickness of bus bar 320 . If the strength (tensile strength) of busbar 310 is high, the rigidity of busbar 310 may be lower than the rigidity of busbar 320 . In some cases, about 0.5 times is sufficient.

As an example, the strength (tensile strength) of busbar 310 is preferably about 0.5 to 20 times the strength of busbar 320 . If the rigidity of busbar 310 is high, the strength of busbar 310 may be lower than the strength of busbar 320 in some cases. In some cases, it is enough.

FIG. 7 shows a busbar 310C as still another example of busbar 310. As shown in FIG. Bus bar 310C includes a welded portion 311C with electrode terminal 110 and an intermediate portion 312C positioned between two welded portions 311C.

As shown in FIG. 7, the busbar 310C is formed in a rectangular shape and has the same shape as the busbar 320A shown in FIG. However, the welded portion 311C of the busbar 310C is formed to have a higher weld strength than the welded portion 321A of the busbar 320A.

Specifically, the welded portion 311C is formed to have a pattern (width, length, depth, area, and number of welds) different from that of the welded portion 321A.

For example, the width, length, and depth of the weld at the weld 311C are preferably about 1 to 5 times the width, length, and depth of the weld at the weld 321A. It is preferable that the area of the welded portion at 321A is about 1 to 10 times the area of the welded portion at the welded portion 321A. As a result, it is preferable that the weld strength of the welded portion 311C is about 1 to 10 times the weld strength of the welded portion 321A.

In addition, the welding strength may be varied between the welded portion 311C and the welded portion 321A by selectively using the same material joining and the dissimilar material joining. That is, the same material (copper-copper) joint has higher welding strength than the dissimilar material (copper-aluminum) joint.

Also, the welding strength may be varied by using different welding methods for the welded portion 311C and the welded portion 321A. For example, the weld strength of a weld formed by laser welding is higher than the weld strength of a weld formed by resistance welding. Furthermore, the welding strength may be varied by varying the welding power or speed. For example, even if the output is the same, the welding strength can be increased by slowing down the welding speed.

Although the embodiments of the present disclosure have been described above, the embodiments disclosed this time should be considered as examples in all respects and not restrictive. The scope of the present disclosure is indicated by the claims, and is intended to include all changes within the meaning and range of equivalents to the claims.

1 Assembled Battery 100 Battery Cell 110 Electrode Terminal 111 Positive Electrode Terminal 112 Negative Electrode Terminal 120 Housing Case 210 End Plate 220 Fastening Member 310, 310A, 310B, 310C, 320, 320A, 330 Bus Bar 311A, 311B , 311C, 321A welding portion, 312A, 312B projecting portion, 312C, 322A intermediate portion, 313A, 313B connecting portion.

Claims (4)

a plurality of storage cells stacked along an arrangement direction and restrained along the arrangement direction;
A plurality of bus bars electrically connecting the plurality of storage cells,
The plurality of bus bars are provided at first positions and second positions where different loads act when the plurality of storage cells are displaced along a direction intersecting the arrangement direction. and a second busbar,
the plurality of storage cells include first terminals and second terminals that are respectively joined to the first bus bar and the second bus bar by welding;
The weld strength of the first bus bar and the first terminal differs from the weld strength of the second bus bar and the second terminal in accordance with the difference in the load between the first position and the second position. , storage module. a welded portion between the first bus bar and the first terminal has a first pattern;
2. The power storage module according to claim 1 , wherein a welded portion between said second bus bar and said second terminal has a second pattern different from said first pattern. 3. The electricity storage module according to claim 2, wherein said first pattern and said second pattern differ from each other in at least one of a group consisting of width, length, depth and number of welded portions. The welded portion between the first bus bar and the first terminal is made of the same material,
The power storage module according to any one of claims 1 to 3, wherein a welded portion between said second bus bar and said second terminal is made of a different material.

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