JP6928546B2 - battery - Google Patents

Description

The present invention relates to a battery, and more particularly to a connection structure between an external terminal and an outermost cell in the battery.

Patent Document 1 discloses that a current collector plate bent in an S shape is used for connection between an external terminal and an outermost cell. Patent Document 2 describes that a porous heat insulating material is arranged between the outermost cell and the case.

Japanese Unexamined Patent Publication No. 2007-299648 Japanese Unexamined Patent Publication No. 2010-531535

When a current collector plate is used for the connection between the external terminal and the outermost cell, the current collector plate on the surface of the outermost cell and the side wall of the case may come into contact with each other at a place other than around the external terminal. Since the current collector plate is a conductor, it easily conducts heat. Therefore, the side wall of the case may act as a strong heat sink for the outermost cell. In this case, a temperature difference occurs between the outermost cell and the inner cell.

An object of the present invention is to provide a connection structure between an external terminal and an outermost cell suitable for reducing the temperature difference between such cells. Such a connection structure includes technical matters concerning the three-dimensional structure of the outermost current collector plate itself.

The battery according to one aspect of the present invention is (a) a case having a side wall with a hole, an external terminal passed through the hole, a group of electrode plates in which positive electrode plates and negative electrode plates are alternately laminated, and an outermost collection. An outermost cell having an electric plate and an inner cell facing the side wall with the outermost cell in between and electrically connected to the outermost cell in series. Be prepared. (B) The outermost current collector plate is formed by an external connection portion joined to the external terminal inside the case with the hole as a boundary, and an end face of any group of the positive electrode plate and the negative electrode plate. It is located between the internal connection portion that is joined to the end face facing the side wall with the outermost current collector plate in between, and the external connection portion and the internal connection portion, and toward the side wall. It has a protruding portion and a protruding portion. (C) Where the protruding portion is supported by the side wall, the external connecting portion floats from the side wall, and the internal connecting portion floats from the side wall, whereby the pole The board group is separated from the side wall.

The external terminal may have a flange arranged on the outside of the case with the hole as a boundary. The case may have a seal ring provided around the hole. The case may be sealed by bringing the flange into close contact with the seal ring due to the stress of the outermost current collector plate.

The outermost current collector plate may have a basic current collector plate and a structural plate. The basic current collector plate may form the internal connection portion and may be joined to the end face of the electrode plate group. The structural plate has the external connection portion, the protrusion portion, and the arm portion, and may be thicker than the basic current collector plate. The arm portion may be attached to the basic current collector plate.

The outermost cell may be opposite in positive and negative to the basic current collector plate, and may further include an internal current collector plate thinner than the structural plate. The internal current collector plate is joined to an upper connection portion that is not joined to the electrode plate group but is electrically connected to other adjacent cells, and to the end face of the electrode plate group whose positive and negative directions are opposite to those of the end face. It may have a lower connection portion to be formed. The lower connection may be further electrically connected to the other cell.

The structural plate is bent in an S shape between the internal connecting portion and the protruding portion, and the structural plate is bent in an S shape in the opposite direction between the protruding portion and the external connecting portion. A protrusion may be formed. The structural plate may not have a constriction that changes the cross-sectional area of the structural plate within the range from the S-shape to the S-shape in the opposite direction.

The structural plate may have legs further outside the external connection portion. The structural plate may be further bent in the opposite S shape between the leg portion and the external connection portion. The external connection portion may be floated from the side wall by supporting the external connection portion between the leg portion and the protrusion portion.

The battery group according to one aspect of the present invention is a battery group obtained by arranging the above batteries in parallel. The side wall of each battery is arranged on the outer edge of the battery group. The battery pack according to one aspect of the present invention includes the above battery group.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a connection structure between an external terminal and an outermost cell suitable for reducing a temperature difference between cells.

Schematic diagram of the cross section of the battery Enlarged sectional view of the connection structure. Sectional view of the joint. Sectional drawing of the cell in IV-IV cross section. The front view and the side view of the structural board of an Example. Sectional drawing of connection structure of comparative example. The front view and the side view of the structural board of the comparative example. The schematic diagram of the heat transfer of an Example. Graph of temperature and SOC (State Of Charge) of an Example. The schematic diagram of the heat transfer of the comparative example. Graph of temperature and SOC of comparative example.

FIG. 1 schematically shows a cross section of the battery 30. For convenience of explanation, the X-axis is taken in the lateral direction corresponding to the longitudinal direction of the battery 30, the Y-axis is taken in the vertical direction, and the Z-axis is taken in the depth direction. This coordinate axis is also used in the following figures.

The battery 30 shown in FIG. 1 includes a case 50, a columnar external terminal 57, outermost cells 20a and 20z, and an inner cell 80b-80e. The inner cells 80b-80e are located between the outermost cells 20a and 20z. These cells are lined up and electrically connected in series. The battery 30 is a module formed by connecting a plurality of cells to each other.

As shown in FIG. 1, the case 50 is an electric tank provided with a side wall 55. As shown in FIG. 4, which will be described later, a side wall including the side wall 55 surrounds these cells. The case 50 is provided with a partition wall 51. In FIG. 1, only the portion of the partition wall 51 extending from the bottom surface of the case 50 is shown, but this is for convenience of explanation. In this embodiment, the partition wall 51 extends to the upper surface of the case 50. The partition wall 51 isolates each cell individually. Further, each cell is individually sealed by the case 50 and the partition wall 51. The coupling between the cells is performed through a hole penetrating the partition wall 51.

In FIG. 1, the cell including the outermost cell 20a may be a secondary battery in a chemical sense. Suitable types of secondary batteries include nickel-metal hydride batteries, lithium-ion batteries and lead-acid batteries.

As shown in FIG. 1, a plurality of batteries 30 may be arranged in parallel on a three-dimensional arrangement to obtain a battery group 40. At this time, the side walls 55 of each battery 30 can be arranged so as to be aligned with each other. As a result, the batteries 30 may be electrically connected in parallel. A battery pack may be manufactured by adding a member such as a control unit, a cooling system, or an open / close switch to the battery group 40.

Although the same hatching is used between the outermost cells 20a and 20z and the inner cells 80b-80e in FIG. 1, it does not indicate that these members are integral members. The cell positions I to III shown in the figure will be described later.

In FIG. 2, the connection structure between the external terminal and the outermost cell is drawn centering on the outermost cell 20a. The symbol (X) indicating the Z axis indicates the direction from the front to the back of the paper. The battery 30 has a characteristic connection structure between the external terminal and the outermost cell. Such a connection structure may be used for the outermost cell 20z shown in FIG.

As shown in FIG. 2, in the outermost cell 20a, the outermost current collector plate 21 is electrically connected to the electrode plate group 70a. Specifically, the internal connection portion 24 of the outermost current collector plate 21 is joined to the end surface 77 of the electrode plate group 70a. The electrode plate group 70a further has an end face 78 on the opposite side of the end face 77. The lower connecting portion 74a of the internal current collector plate 71a is joined to the end face 78. These joints can be performed, for example, by welding.

FIG. 2 shows the internal current collector plates 71a and 71b bent in an S shape. These internal current collector plates have lower connecting portions 74a and 74b. The outermost cell 20a and the inner cell 80b are formed by joining these connecting portions to the end faces of the side portions of the electrode plate group 70a and the electrode plate group 70b. The joining may be performed by welding. These internal current collector plates have upper connecting portions 72a and 72b, respectively. The upper connecting portions 72a and 72b do not come into contact with the electrode plate group.

As shown in FIG. 2, bent portions 75a and 75b are provided between these upper connecting portions and the lower connecting portions. At these bent portions, each internal current collector plate is bent in an S shape. Due to the bending, the upper connecting portions 72a and 72b move away from the electrode plate group and approach the adjacent cells. By joining these upper connecting portions to each other, the outermost cell 20a and the inner cell 80b are electrically connected. The joining may be performed by welding. In FIG. 2, only the portion of the partition wall 51 extending from the bottom surface of the case 50 is shown. As described above, the partition wall 51 extends to the upper surface of the case 50 in the present embodiment. The same is true in FIG.

As shown in FIG. 2, the outermost cell 20a is arranged between the side wall 55 and the inner cell 80b. The inner cell 80b faces the side wall 55 with the outermost cell 20a in between. The side wall 55 is provided with a hole 56. The outermost current collector plate 21 is joined to the external terminal 57 inside the case 50 with the hole 56 as a boundary.

As shown in FIG. 2, the outermost current collector plate 21 has an external connection portion 22 as a superstructure. The external connection portion 22 is not joined to the electrode plate group 70a. The external connection portion 22 faces the external terminal 57. The external terminal 57 electrically connects the inside and outside of the case 50. The external terminal 57 is also called a pole pillar. The external terminal 57 passes through the hole 56. The external connection portion 22 and the external terminal 57 are joined to each other.

As shown in FIG. 2, in the outermost current collector plate 21, there are a bent portion 25a and a bent portion 25b between the external connecting portion 22 and the internal connecting portion 24. The bent portion 25a and the bent portion 25b are bent in opposite directions to each other. Based on the appearance of the figure, the bent portion 25a is bent in an inverted S shape, and the bent portion 25b is bent in an S shape. The S-shaped and inverted S-shaped expressions are relative and expedient. Looking at the figure from the back side, the S-shape and the inverted S-shape are interchanged. In the bent portion 25a, the outermost current collector plate 21 is bent so that the external connecting portion 22 approaches the electrode plate group 70a.

As shown in FIG. 2, a protruding portion 23 is formed between the external connecting portion 22 and the internal connecting portion 24. Specifically, there is a protruding portion 23 between the bent portion 25a and the bent portion 25b. Alternatively, the protruding portion 23 is formed by the bent portion 25a and the bent portion 25b. In the bent portion 25b, the outermost current collector plate 21 is bent so that the protruding portion 23 is away from the electrode plate group 70a. The protruding portion 23 projects toward the side wall 55.

As shown in FIG. 2, the external terminal 57 has a flange 58. The flange 58 may be integrally formed with the external terminal 57. The flange 58 is arranged on the outside of the case 50 with the hole 56 as a boundary. The hole 56 is closed with a flange 58. The case 50 may be sealed by providing a gasket between the flange 58 and the side wall 55. It is preferable to seal the case 50 based on a force that drags the external terminal 57 generated in the outermost current collector plate 21 into the inside of the case 50, that is, so-called stress.

As shown in FIG. 2, the protruding portion 23 is in contact with the side wall 55. Therefore, the protrusion 23 is supported by the side wall 55. Since the protruding portion 23 serves as a fulcrum, the external connecting portion 22 floats from the peripheral portion of the hole 56. The periphery of the hole 56 may be flat.

As shown in FIG. 2, the outermost current collector plate 21 may further include a leg portion 28 and a bent portion 25c. The legs 28 are located further outside the external connection 22. In the figure, the leg portion 28 is located further above the external connection portion 22. The external terminal 57 is located between the protrusion 23 and the leg 28 in the case 50. The bent portion 25c is curved in an S shape opposite to that of the bent portion 25a.

As shown in FIG. 2, the leg portion 28 and the protruding portion 23 support the external connecting portion 22, and the external connecting portion 22 is floated from the peripheral portion of the hole 56. Floating the external connection portion 22 in this way is effective in obtaining the stress as described below.

FIG. 3 is a cross-sectional view showing a joint portion provided on the upper part of the outermost current collector plate 21. A so-called leaf spring type structure is formed by the projecting portion 23, the bent portion 25a, the external connecting portion 22, the bent portion 25c, and the leg portion 28. The leg portion 28 and the protruding portion 23 are in contact with the inner surface of the side wall 55. The leaf spring type structure may be formed only by the protruding portion 23, the bent portion 25a, and the external connecting portion 22.

In FIG. 3, when the outermost current collector plate 21 is pushed in the direction of the hole 56, stress is generated in the leaf spring type structure of the outermost current collector plate 21. The figure also shows the place where the outermost current collector plate 21 is plastically deformed. The stress of the outermost current collector plate 21 is a force that tries to return the external connection portion 22 to the original position as much as possible. The stress acts strongly to drag the external terminal 57 inside the case 50 as indicated by the arrow pointing to the right. Therefore, the adhesion between the flange 58 and the case 50 can be strengthened.

In FIG. 3, a force that pulls the outermost current collector plate 21 toward the side wall 55 acts as a reaction to the force that pulls the external terminal 57. To counter this, the outermost current collector plate 21 supports itself by the protrusions 23 and the legs 28. As a result, the protrusion 23 and the leg 28 push the side wall 55. A force as indicated by the arrow pointing to the left is applied to the side wall 55.

When joining the external connection portion 22 and the external terminal 57 in FIG. 3, they may be joined by spot welding from the side of the external connection portion 22 on the joint surface 59. At this time, it is preferable to push the floating external connection portion 22 toward the external terminal 57 in advance as shown in the figure. By welding while pushing the external connection portion 22, stress acting on the external terminal 57 can be generated after joining. The magnitude of the stress generated by adjusting the length from the flange 58 to the joint surface 59 at the external terminal 57 to be appropriately shorter may be adjusted. Although the leaf spring type structure has been described above as being plastically deformed, the leaf spring type structure may be elastically deformed to exert a spring force as stress.

Return to FIG. The upper part of the case 50 may be a lid separate from the side wall 55 and the like. After joining the external connection portion 22 and the external terminal 57, the case 50 may be completed by attaching a lid over the upper end of the side wall including the side wall 55.

As shown in FIG. 2, the internal connection portion 24 is not in contact with the side wall 55. Since the protruding portion 23 serves as a fulcrum, the internal connecting portion 24 also floats from the side wall 55. As a result, the electrode plate group 70a can be separated from the side wall 55. The portion of the side wall 55 facing the internal connection portion 24 may be flat. A space 35 is formed between the internal connection portion 24 and the side wall 55. The space 35 becomes an air layer filled with air. The electrolytic solution may enter the space 35. Air may be replaced with a gas other than air. The function of the space 35 will be described in the examples.

FIG. 4 shows a cross section of the battery 30 in the cross section IV-IV shown in FIG. The symbol (dot) indicating the Y-axis indicates the direction from the back to the front of the paper. The outermost cell 20a has an electrode plate group 70a, an outermost current collector plate 21, and an internal current collector plate 71a. In the figure, the outermost current collector plate 21 is drawn as being composed of two bodies, a basic current collector plate 31 and a structural plate 32. This detail will be described in Examples.

As shown in FIG. 4, the electrode plate group 70a is a stack of a plurality of flat electrode plates. Here, the positive electrode plates 61 and the negative electrode plates 62 are alternately laminated. A separator 65 is arranged between the positive electrode plate 61 and the negative electrode plate 62. The outer surface of the electrode plate group 70a is a negative electrode plate 62. These negative electrode plates 62 are covered with a separator 65.

As shown in FIG. 4, the outermost current collector plate 21 is joined to the end face of any group of the positive electrode plate 61 and the negative electrode plate 62. In the figure, the outermost current collector plate 21 is joined to the end face 77 of the group of positive electrode plates 61. The positive electrode plate 61 has a lead portion 63. The end face 77 is located on the side of the lead portion 63 in the positive electrode plate 61.

As shown in FIG. 4, the internal current collector plate 71a is joined to the end surface 78 on the side opposite to the end surface 77. As shown in the figure, the end face 78 is the end face of the group of the negative electrode plates 62. The negative electrode plate 62 has a lead portion 64. The end face 78 is located on the side of the lead portion 64 in the negative electrode plate 62.

As shown in FIG. 4, the case 50 is rectangular in cross section. In the rectangle, the X-axis direction is the longitudinal direction. The side wall 55 particularly refers to the side wall facing the end face 77. The case 50 has a side wall 54a in the + Z direction and a side wall 54b in the −Z direction. The side wall 55 is located between the side walls 54a and 54b. The side wall 55 corresponds to the short side of the rectangle, and the side walls 54a and 54b correspond to the long side of the rectangle. These side walls 54a and 54b face the outer surface of the electrode plate group 70a parallel to the positive electrode plate 61 and the negative electrode plate 62.

In FIG. 4, the side walls 54a and 54b and the electrode plate group 70a are separated from each other. This is for convenience in the illustration, and in practice these intervals may be small. By reducing the spacing, the side walls 54a and 54b may efficiently function as heat sinks for each cell including the outermost cell 20a.

In order to make the case 50, the side wall 55 and the side wall including the side walls 54a and 54b may be integrally molded. The cell is surrounded on all sides by these side walls and the above-mentioned partition walls. The case 50 is made of an insulator. The insulator may be a resin.

Although the same hatching is used between the positive electrode plates 61 in FIG. 4, it does not indicate that these members are integral members. The same applies to each negative electrode plate 62. Further, the hatching of the separator 65 is omitted.

<1. Battery Configuration of Examples>

The front view of the outermost current collector plate 21 according to the embodiment is shown on the left side of FIG. The left side view of the outermost current collector plate 21 is shown on the right side of FIG. Internal current collector plates 71a and 71b are also shown. The other components of the battery are represented by alternate long and short dash lines. The outermost current collector plate 21 may be separated into two bodies as shown in FIG.

As shown in FIG. 5, the outermost current collector plate 21 has a basic current collector plate 31 and a structural plate 32. The structural plate 32 is a conductor. The basic current collector plate 31 is a part that constitutes the internal connection portion 24. The basic current collector plate 31 is joined to the end face 77. The structural plate 32 is attached to the basic current collector plate 31. The structural plate 32 and the foundation current collector plate 31 may be joined by welding. Conduction is performed between the structural plate 32 and the electrode plate group 70a via the basic current collector plate 31.

As shown in FIG. 5, the structural plate 32 has an external connecting portion 22, a protruding portion 23, and bent portions 25a and 25b. The structural plate 32 has a function as an external connecting portion 22 and a protruding portion 23. The structural plate 32 further includes a leg portion 28 and a bent portion 25c.

As shown in FIG. 5, the structural plate 32 includes an arm portion 27. A basic current collector plate 31 is attached to the arm portion 27. The arm portion 27 and the foundation current collector plate 31 may be joined by welding. The arm portion 27 is a part constituting the internal connection portion 24. The arm portion 27 and the basic current collector plate 31 function as an internal connection portion 24. The bent portion 25b creates a step between the surface of the arm portion 27 and the inner surface of the side wall 55.

As shown in FIG. 5, the lower end of the arm portion 27 and the lower end of the basic current collector plate 31 do not have to be aligned in height. The lower end of the arm portion 27 may be higher than the lower end of the basic current collector plate 31. Thereby, three-dimensional interference between the hole 48 for the insert nut and the arm portion 27 may be avoided. The hole 48 may be provided at the lower end of the side wall 55. The holes 48 help secure the battery to a given external structural material. On the other hand, the lower end of the basic current collector plate 31 may be aligned with the lower end of the lower connection portion 74a of the internal current collector plate 71a.

As shown in FIG. 5, the structural plate 32 is thicker than the basic current collector plate 31. The structural plate 32 has less deflection than the basic current collector plate 31. Therefore, the structural plate 32 is more useful for fixing the position of the cell 20a in the case 50. The structural plate 32 serves to provide a space 35 between the cell 20a and the side wall 55.

As shown in FIG. 5, the protruding portion 23, the bent portion 25a, and the bent portion 25b are all thicker than the basic current collector plate 31. Therefore, when the current flows in the order of the electrode plate group 70a, the basic current collector plate 31, the structural plate 32, and the external terminal 57, the electric resistance in the section is relatively small. For example, the electric resistance can be reduced as compared with the case where only the current collector plate having the same thickness as the basic current collector plate 31 is used as the outermost current collector plate without using the structural plate.

<2. Manufacture of structural boards>

Since the structural plate 32 is thick as shown in FIG. 5, the material processing method for manufacturing the structural plate 32 may be devised. As an example, the structural plate 32 may be created as follows. A bent portion 25a is located between the external connecting portion 22 and the protruding portion 23. Therefore, a flat plate (1.2 mm thick) having a predetermined width and length is bent into an S shape to form a bent portion 25a.

As shown in FIG. 5, a bent portion 25b is located between the internal connecting portion 24 or the arm portion 27 and the protruding portion 23. Therefore, the flat plate bent as described above is further bent into an S shape to form the bent portion 25b. As a result, the space 35 may be formed as an air layer (thickness of 0.6 mm).

As shown in FIG. 5, a bent portion 25c is located between the leg portion 28 and the external connecting portion 22. Therefore, the flat plate bent as described above is further bent into an S shape to form the bent portion 25c. The order of these bends does not matter. These bends may be performed all at once with a mold or the like.

By the above steps, the protruding portion 23 is formed as shown in FIG. It is preferable that the cross-sectional area of the structural plate 32 does not change in the range from the S-shape of the bent portion 25b to the S-shape in the opposite direction of the bent portion 25a. However, there may be some stretching of the material due to bending.

<3. Battery configuration of comparative example>

The battery 90 of the present comparative example shown in FIG. 6 is different from the battery of the embodiment in the following points. The battery 90 has a connection structure between the external terminal and the outermost cell. In the outermost cell 80a, the outermost current collector plate 91 is connected to the electrode plate group 70a. The internal connection portion 94 of the outermost current collector plate 91 is joined to the side surface of the electrode plate group 70a. The outermost current collector plate 91 includes an external connection portion 92 as a superstructure. The external connection portion 92 is joined to the external terminal 57.

As shown in FIG. 6, there is a bent portion 95 between the external connecting portion 92 and the internal connecting portion 94. It is the same as in the embodiment that the stress of the bent portion 95 can be used to strengthen the adhesion between the flange 58 and the case 50. The outermost current collector plate 91 is also bent in an S shape at the bent portion 95. The outermost current collector plate 91 is bent so that the external connection portion 92 approaches the electrode plate group 70a.

In FIG. 6, the stress generated by the outermost current collector plate 91 works strongly so as to drag the flange 58 inside the case 50, which is the same as that of the embodiment. On the other hand, unlike the embodiment, the internal connection portion 94 is attached to the inner surface of the case 50 so as to support the bent portion 95. Therefore, the internal connection portion 94 acts as a powerful heat sink for the electrode plate group 70a.

The front view of the outermost current collector plate 91 according to the comparative example is shown on the left side of FIG. 7. The left side view of the outermost current collector plate 91 is shown on the right side of FIG. 7. The outermost current collector plate 91 has a structure composed of two bodies, a basic current collector plate 31 and a structural plate 97. The basic current collector plate 31 is joined to the end face 77. The structural plate 97 is attached to the basic current collector plate 31.

As shown in FIG. 7, the structural plate 97 includes an extending portion 93. A basic current collector plate 31 is attached to the extending portion 93. The extending portion 93 is a part constituting the internal connecting portion 94. The structural plate 97 is thicker than the basic current collector plate 31.

As shown in FIG. 7, the extending portion 93 extends straight downward from the bent portion 95. Therefore, the extending portion 93 is in surface contact with the side wall 55. There is no space between the end face 77 and the side wall 55. The structural plate 97 is thicker than the above-mentioned structural plate 32 (FIG. 5) in accordance with the fact that no space is provided.

In FIG. 7, the structural plate 97 is created as follows. A bent portion 95 is located between the external connecting portion 22 and the extending portion 93. A slightly thick flat plate (1.8 mm thick) is bent into an S shape to form a bent portion 95. A bent portion 96 is located between the leg portion 98 and the external connecting portion 92. Therefore, the flat plate bent as described above is further bent into an S shape to form the bent portion 96.

As shown in FIG. 7, notches 99a-99d are provided in advance on the side portions of the flat plate in order to facilitate bending at the bent portions 95 and 96. The notches 99a and 99b are located on both sides of the bent portion 95 when the structural plate 97 is viewed from the side wall 55 side. The cutouts 99c and 99d are located on both sides of the bent portion 96.

<4. Electrical resistance in the connection structure between the external terminal and the outermost cell>

Since the bent portion 95 is provided with a notch as shown in FIG. 7, the cross section of the bent portion 95 is smaller than the cross section of the other portion. Therefore, when a current flows from the electrode plate group 70a toward the external terminal 57, the electric resistance is large. This indicates that the current is concentrated in the constricted portion sandwiched between the notches 99a and 99b.

Return to FIG. In the structural plate 32 according to the embodiment, it is preferable that the bent portions 25a and 25b are not provided with notches. It is preferable that there is no constriction that changes the cross-sectional area of the structural plate 32 in the range from the S-shape of the bent portion 25b to the S-shape in the opposite direction of the bent portion 25a. Since the structural plate 32 is thinner than the structural plate 97, it is relatively easy to bend. Therefore, the notch is not essential. A notch may be provided in the bent portion 25c.

As shown in FIG. 5, in the embodiment, the cross-sectional area of the structural plate 32 does not change in the range from the S-shape of the bent portion 25b to the S-shape of the bent portion 25a in the opposite direction. The electrical resistance of the structural plate 32 is preferably smaller than that of the structural plate 97. In this way, the electrical resistance in the connection structure between the external terminal and the outermost cell can be reduced. The generation of Joule heat is suppressed by reducing the electrical resistance in the range from the S-shape of the bent portion 25b to the S-shape in the opposite direction of the bent portion 25a.

In FIG. 5, reducing the electrical resistance in the connection structure between the external terminal and the outermost cell has a positive effect on the sealing of the battery. A seal ring 49 used as a gasket is provided around the hole 56. The battery is sealed by the close contact between the flange 58 and the seal ring 49. The Joule heat generated between the external terminal and the outermost cell is transferred to the seal ring 49 and wears the seal ring 49. However, in this embodiment, the Joule heat is suppressed, so that the seal ring 49 is not easily worn.

<5. Electrical resistance between cells>

In FIG. 5, the electric resistance between the outermost cell 20a and the inner cell 80b may be further reduced in accordance with the reduction of the electric resistance in the structural plate 32. The positive and negative directions of the internal current collector plate 71a are opposite to those of the basic current collector plate 31. The internal current collector plate 71a may be thinner than the structural plate 32. As described above, in the internal current collector plate 71a, the upper connecting portion 72a is not joined to the electrode plate group 70a. The upper connecting portion 72a is joined to the inner cell 80b. The upper connecting portion 72a is joined to the upper connecting portion 72b.

As shown in FIG. 5, the lower connecting portion 74a is joined to the end face 78. The end face 78 is opposite to the end face 77 in the positive and negative directions. The lower connecting portion 74a is further joined to the internal cell 80b via the conductive portion 73. The lower connecting portion 74a is joined to the lower connecting portion 74b via the conductive portion 73. The joining may be performed by welding.

As shown in FIG. 5, the internal current collector plate 71a is electrically connected not only between the upper connecting portions 72a and 72b but also between the lower connecting portions 74a and 74b. Therefore, the electrical resistance between the outermost cell 20a and the inner cell 80b can be reduced. The electrical resistance between the internal cells can be reduced by the same method.

As described above, the electric resistance can be reduced not only between the outer terminal and the outermost cell but also between the outermost cell and the inner cell and between the inner cell and the inner cell. The output of each cell may be increased accordingly. Since the electrical resistance of each part is small, local heat generation in the battery can be suppressed even if the cell output is large.

<6. Temperature variation for each cell and cell charge capacity>

FIG. 8 shows a schematic diagram of heat transfer in the battery according to the embodiment. The heat generated in the outermost cell is transferred to the basic current collector plate 31 and further to the arm 27 by heat conduction through the route 41. In the figure, the positive electrode plate 61 is shown on behalf of each member in the outermost cell. The heat of the arm 27 is transferred to the side wall 55 of the case through the route 42. However, the space 35 interferes with heat conduction. Therefore, the temperature rise on the side wall 55 is relatively small. Further, the heat radiated from the side wall 55 is relatively small. Part of the heat of the arm 27 is transferred back to the outermost cell by heat conduction through the route 44. As a result, the temperature of the outermost cell is kept relatively high.

FIG. 9 shows a graph of the temperature and SOC for each cell position in the battery according to the embodiment. The cell positions I to III shown in FIG. 9 are based on the description in FIG. As shown in FIG. 1, the outermost cell 20a is arranged at the cell position I. Cell position II is adjacent to cell position I. An internal cell 80b is arranged at the cell position II. Cell position III is adjacent to cell position II. An internal cell 80c is arranged at the cell position III.

As shown in FIG. 9, the cell temperature at cell positions I to III is uniform. Therefore, the SOC at cell positions I to III, the so-called charge capacity, is constant. Therefore, there is little variation in the charging capacity of each cell in the battery. With the battery of the embodiment, charge / discharge control is relatively easy.

FIG. 10 shows a schematic diagram of heat transfer in the battery according to the comparative example. The heat generated in the outermost cell is transferred to the basic current collector plate 31, the extending portion 93, and the side wall 55 by heat conduction through the route 46. This is because the members are in contact with each other on the surface. In the figure, the positive electrode plate 61 is shown on behalf of the outermost cell. The heat radiated from the side wall 55 is relatively large. Therefore, the side wall 55 efficiently functions as a heat sink for the outermost cell.

FIG. 11 shows a graph of the temperature and SOC for each cell position in the battery according to the comparative example. There is no difference from FIG. 1 in the cell arrangement order. The cell temperature at cell position I is lower than the cell temperature at cell position II and cell position III. Therefore, the SOC at cell position I is higher than the SOC at cell position II and cell position III. Therefore, the charge capacity of each cell varies in the battery. It is relatively difficult to control charging and discharging with the battery of the comparative example.

<7. Application to battery group>

Return to FIG. The side wall 55 of each battery 30 is arranged flush with the outer edge of the battery group 40. The above-mentioned problem that the outermost cell facing the side wall 55 is easily cooled in each battery 30 remains. Therefore, it is preferable to use the connection structure between the external terminal and the outermost cell of the present embodiment also in the battery group or the battery pack.

20a outermost cell, 20z outermost cell, 21 outermost current collector plate, 22 external connection part, 23 protrusion, 24 internal connection part, 25ac flexion part, 27 arm part, 28 leg part, 30 battery, 31 foundation Current collector plate, 32 structural plate, 35 space, 40 battery group, 41 route, 42 route, 44 route, 46 route, 48 hole, 49 seal ring, 50 case, 51 partition wall, 54ab side wall, 55 side wall, 56 hole , 57 External terminal, 58 flange, 59 joint surface, 61 positive electrode plate, 62 negative electrode plate, 63 lead part, 64 lead part, 65 separator, 70ab electrode plate group, 71ab internal current collector plate, 72ab upper part Connection part, 73 Conduction part, 74ab Lower connection part, 75ab Bend part, 77 End face, 78 End face, 80a Outer cell, 80b-80e Inner cell, 90 Battery, 91 Outer current collector plate, 92 External connection Part, 93 Extension part, 94 Internal connection part, 95 Bend part, 96 Bend part, 97 Structural plate, 98 Leg part, 99a-99d notch, I-III cell position

Claims (8)

(A) A case having a side wall with a hole and
With the external terminal passed through the hole,
A group of electrode plates in which positive electrode plates and negative electrode plates are alternately laminated , and an outermost cell having an outermost current collector plate for connecting to the external terminal.
An internal cell facing the side wall with the outermost cell in between, which is electrically connected in series with the outermost cell.
With
(B) The outermost current collector plate is
An external connection portion that is joined to the external terminal inside the case with the hole as a boundary,
An internal connection portion that is an end face of any group of the positive electrode plate and the negative electrode plate and is joined to the end face facing the side wall with the outermost current collector plate in between.
A protrusion located between the external connection portion and the internal connection portion and protruding toward the side wall, and a protrusion.
Have,
(C) Where the protrusion is supported by the side wall
The external connection portion floats from the side wall, and the internal connection portion floats from the side wall, so that the electrode plate group is separated from the side wall.
battery. The external terminal has a flange arranged on the outside of the case with the hole as a boundary.
The case has a seal ring provided around the hole.
The case is sealed by bringing the flange into close contact with the seal ring due to the stress of the outermost current collector plate.
The battery according to claim 1. The outermost current collector plate has a basic current collector plate and a structural plate.
The basic current collector plate constitutes the internal connection portion and is joined to the end face of the electrode plate group.
The structural plate has the external connection portion, the protrusion portion and the arm portion, and is thicker than the basic current collector plate.
The arm is attached to the basic current collector plate,
The battery according to claim 2. The outermost cell is opposite in positive and negative to the basic current collector plate, and further includes an internal current collector plate thinner than the structural plate.
Although the internal current collector plate is not joined to the electrode plate group, it has an upper connection portion that is electrically connected to other adjacent cells.
It has a lower connecting portion that joins to the end face of a group of electrode plates whose positive and negative directions are opposite to those of the end face.
The lower connection is further electrically connected to the other cell.
The battery according to claim 3. The structural plate is bent in an S shape between the internal connecting portion and the protruding portion, and the structural plate is bent in an S shape in the opposite direction between the protruding portion and the external connecting portion. A protrusion is formed,
The structural plate does not have a constriction that changes the cross-sectional area of the structural plate within the range from the S-shape to the reverse S-shape.
The battery according to claim 3 or 4. The structural plate has legs further outside the external connection.
Between the legs and the external connection, the structural plate is further bent into the opposite S-shape.
The external connection portion is lifted from the side wall by supporting the external connection portion between the leg portion and the protrusion portion.
The battery according to claim 5. A group of batteries obtained by arranging the batteries according to any one of claims 1 to 6 in parallel.
The side wall of each battery is arranged on the outer edge of the battery group.
Battery group. A battery pack comprising the battery group according to claim 7.

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