JP7672437B2 - Electricity storage device and method for manufacturing the same. - Google Patents

Description

This disclosure relates to an electricity storage device and a method for manufacturing an electricity storage device.

Conventionally, there is known an electric storage device that includes an electrode body having a pair of opposing wide surfaces, a case that houses the electrode body, and a terminal that is electrically connected to the electrode body. In recent years, as electric storage devices have become more widespread, there is a demand for even higher output. In this regard, for example, Patent Document 1 and Patent Document 2 disclose technology related to a heat sink (heat dissipation member) for dissipating heat generated from the electrode body (laminated body or electrode assembly).

JP 2010-287487 A JP 2016-31851 A

However, when joining the heat dissipation member and the case as described in Patent Document 2, if the case (container) used in the above-mentioned conventional technologies (Patent Documents 1 and 2) is used, the opening is narrow, which causes problems such as interference with the welding jig and scattering of spatter. Therefore, there is room for improvement in the above technology.

The technology disclosed herein has been developed in light of the above circumstances, and its purpose is to provide an electricity storage device and a method for manufacturing an electricity storage device.

The power storage device disclosed herein is an electrode body having a positive electrode and a negative electrode, the electrode body having a pair of opposing wide surfaces, a hexahedral case housing a plurality of the electrode bodies, the case having a wide rectangular first surface and an opening facing the first surface, a pair of opposing second surfaces extending from the periphery of the first surface toward the opening, and a pair of opposing third surfaces extending from the outer edge of the first surface toward the opening, a wide rectangular sealing plate that seals the opening and faces the first surface, and a heat dissipation member housed in the case, wherein the heat dissipation member includes a heat dissipation plate arranged in contact with the wide surface of the electrode body, and a first side wall extending from one end of the heat dissipation plate along the inner surface of the case toward the opening, and a metal joint that joins the first side wall to the second surface and/or the third surface of the case.

According to this configuration, the heat dissipation member has a first side wall, which increases the contact area between the case and the heat dissipation member, and the heat of the heat dissipation member can be conducted to the case. And, by having a metal joint that joins the first side wall to the second surface and/or the third surface of the case, the heat of the heat dissipation member can be conducted to the case more suitably. Furthermore, since the above-mentioned case body has a wide rectangular opening, the above-mentioned heat dissipation member can be easily arranged (housed) inside the case body. Also, when forming the metal joint, the irradiation distance of the laser light can be shortened. This makes it possible to suppress the scattering of spatter when forming the metal joint. Therefore, according to the electricity storage device disclosed herein, it is possible to improve the heat dissipation efficiency of the electricity storage device while suitably suppressing the intrusion of foreign matter inside the case body.

FIG. 1 is a perspective view that illustrates a schematic diagram of an electricity storage device according to a first embodiment. FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. FIG. 3 is a schematic vertical cross-sectional view taken along line III-III in FIG. FIG. 4 is a schematic diagram of the electrode body according to the first embodiment. FIG. 5 is a perspective view showing the heat dissipation member according to the first embodiment. FIG. 6 is a perspective view showing a rear surface of the heat dissipation member according to the first embodiment. FIG. 7 is a schematic diagram illustrating the arrangement of the heat dissipation member in the case body according to the first embodiment. FIG. 8 is a view of the electricity storage device according to the second embodiment, which corresponds to FIG. FIG. 9 is a perspective view showing a heat dissipation member according to the second embodiment. FIG. 10 is a flow diagram showing a method for manufacturing an electricity storage device according to one embodiment. FIG. 11 is a perspective view showing a heat dissipation member according to a modified example.

Below, the embodiments of the technology disclosed herein are described with reference to the drawings. Matters not mentioned in this specification but necessary for implementing the technology disclosed herein can be understood as design matters for a person skilled in the art based on the conventional technology in the field. The technology disclosed herein can be implemented based on the contents disclosed in this specification and the technical common sense in the field. In the following drawings, the same reference numerals are used to describe members and parts that perform the same function. The dimensional relationships (length, width, thickness, etc.) in each figure do not reflect the actual dimensional relationships. In this specification, the numerical range expressed as "A to B" includes A and B, and also includes the meanings of "preferably larger than A" and "preferably smaller than B."

In this specification, the term "energy storage device" refers to a device that can be charged and discharged. Energy storage devices include batteries generally referred to as lithium ion batteries and lithium secondary batteries, as well as lithium polymer batteries and lithium ion capacitors. A secondary battery generally refers to a battery that can be repeatedly charged and discharged by the movement of charge carriers between the positive and negative electrodes. Here, a lithium ion secondary battery is given as an example of one form of energy storage device.

First Embodiment
FIG. 1 is a perspective view showing a schematic diagram of an electric storage device 100 according to a first embodiment. FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. 3. FIG. 3 is a schematic vertical cross-sectional view taken along line III-III in FIG. 1. In FIG. 2, the electrode body 20 is shown in an outline view of the cross section inside the case 10. In FIG. 3, for convenience of explanation, the number of negative electrode tabs 24t is shown as 11, but this is not limited thereto. In the following explanation, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom (gravity direction). In addition, the symbol X in the drawings indicates the short side direction (also referred to as the thickness direction) of the electric storage device 100, the symbol Y indicates the long side direction of the electric storage device 100, and the symbol Z indicates the vertical direction (also referred to as the height direction). However, these are merely directions for convenience of explanation, and do not limit the installation form of the electric storage device 100 in any way.

As shown in Figures 1 and 2, the electricity storage device 100 includes a case 10, an electrode body 20, a positive electrode terminal 30, and a negative electrode terminal 40. Although not shown, the electricity storage device 100 further includes an electrolyte. The electricity storage device 100 is preferably a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery.

The case 10 is, for example, a hexahedral member that houses the electrode body 20. As shown in Figs. 1 and 2, the case 10 includes a case body 12 and a sealing plate 14. The case 10 is typically made of a metal such as aluminum, an aluminum alloy, or stainless steel (SUS).

The case body 12 is, for example, the main body of the case 10 that houses the electrode body 20 therein. As shown in FIG. 1 and FIG. 2, the case body 12 has an opening 12h, a first surface 12a, a pair of opposing second surfaces 12b, 12c, and a pair of opposing third surfaces 12d, 12e. In this embodiment, the first surface 12a is a wide rectangular shape and faces the opening 12h. The pair of second surfaces 12b, 12c extend from a pair of opposing peripheries of the first surface 12a (here, the long sides of the first surface 12a), and the second surfaces 12b, 12c face each other. As shown in FIG. 1 and FIG. 2, the lower second surface 12c constitutes the bottom surface of the electricity storage device 100. The upper second surface 12b is the upper surface facing this bottom surface, and is the mounting surface for the positive electrode terminal 30 and the negative electrode terminal 40 here. The pair of third surfaces 12d, 12e extend from a pair of opposing peripheries of the first surface 12a (here, the short sides of the first surface 12a), and the third surfaces 12d, 12e face each other. The shape and size of the case body 12 can be changed as appropriate, for example, according to the size and number of the electrode bodies 20 housed in the case body 12. In this specification, the term "rectangular" includes a shape in which linear long and short sides are joined to each other via a curve, a shape in which at least one of the long and short sides is not linear but is curved, uneven, or bent to be composed of multiple straight lines or curves, and the like.

The opening 12h is, for example, a portion where the sealing plate 14 is attached. Here, the opening 12h is formed by being surrounded by the upper edges of the pair of second surfaces 12b, 12c and the upper edges of the pair of third surfaces 12d, 12e, and has a wide rectangular shape. The sealing plate 14 is fitted into the opening 12h of the case body 12, and the periphery of the sealing plate 14 is welded, whereby the case body 12 and the sealing plate 14 are integrated, and the case 10 is hermetically sealed.

2, the second surface 12b is provided with a discharge valve 15, a liquid injection hole 16, and through holes 18 and 19. The discharge valve 15 is, for example, a thin-walled portion. Here, the discharge valve 15 is configured to break when the pressure inside the case 10 reaches a predetermined value or more, thereby discharging the gas inside the case 10 to the outside. The liquid injection hole 16 is a through hole for injecting the electrolyte into the inside of the case 10 after the sealing plate 14 is assembled to the case body 12. Here, the liquid injection hole 16 is sealed by a sealing member 16a after the electrolyte is injected. The through hole 18 is a portion where the positive electrode terminal 30 is attached (inserted). The through hole 19 is a portion where the negative electrode terminal 40 is attached (inserted). The second surface 12c is an example of the "second surface without a through hole" disclosed herein.

The sealing plate 14 is a flat plate-like member that seals the opening 12h. Therefore, the shape of the sealing plate 14 should correspond to the shape of the opening 12h. Here, the sealing plate 14 is a wide rectangle. Here, when the sealing plate 14 is attached to the opening 12h, the sealing plate 14 faces the first surface 12a.

As the electrolyte, any electrolyte that has been publicly known and is used can be used without any particular limitation. As an example, a non-aqueous electrolyte in which a supporting salt (electrolyte salt) is dissolved in a non-aqueous solvent (organic solvent) is preferably used. As an example of the non-aqueous solvent, a carbonate-based solvent such as ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, etc. can be mentioned. As an example of the supporting salt, a fluorine-containing lithium salt such as _LiPF6 can be mentioned. The electrolyte may contain an additive as necessary.

The positive electrode terminal 30 is a member electrically connected to the positive electrode 22 of the electrode body 20. As shown in FIG. 2, the positive electrode terminal 30 is inserted into the through hole 18 and exposed to the outside of the case body 12. Here, the positive electrode terminal 30 has a positive electrode first conductive member 31 and a positive electrode second conductive member 32. In this embodiment, the positive electrode first conductive member 31 has a shaft portion 31a and a base portion 31b. The shaft portion 31a is, for example, cylindrical, and is a portion that is inserted into the through hole 18 and the through hole of the positive electrode second conductive member 32. The base portion 31b is, for example, flat, and is a portion that is disposed along the outer surface (here, the second surface 12b) of the case body 12. The positive electrode second conductive member 32 is, for example, flat, and is a portion that is connected to the bus bar when constructing a stack. In this embodiment, the positive electrode second conductive member 32 is rectangular. The positive electrode first conductive member 31 and the positive electrode second conductive member 32 are connected to each other on the outside of the case 10. The positive electrode first conductive member 31 is made of, for example, aluminum or an aluminum alloy. The positive electrode second conductive member 32 is made of, for example, aluminum, an aluminum alloy, copper, a copper alloy, or the like. The positive electrode terminal 30 is an example of the "terminal" disclosed herein.

The negative electrode terminal 40 is a member electrically connected to the negative electrode 24 of the electrode body 20. As shown in FIG. 2, the negative electrode terminal 40 is inserted into the through hole 19 and exposed to the outside of the case body 12. Here, the negative electrode terminal 40 has a negative electrode first conductive member 41 and a negative electrode second conductive member 42. The negative electrode first conductive member 41 is made of, for example, copper or a copper alloy. The negative electrode terminal 40 may have, for example, the same configuration as the positive electrode terminal 30. For this reason, a description of the configuration of the negative electrode terminal 40 is omitted here. The negative electrode terminal 40 is an example of a "terminal" disclosed herein.

The positive electrode collector 50 is, for example, a member that electrically connects the positive electrode tab 22t and the positive electrode terminal 30. The positive electrode collector 50 is a plate-shaped conductive member. As shown in FIG. 2, the positive electrode collector 50 extends along the inner surface of the case body 12 (here, the inside of the second surface 12b) in the long side direction of the second surface 12b. The positive electrode tab 22t (here, the positive electrode tab group) is connected to one end (the right end in FIG. 2) of the positive electrode collector 50. In addition, the other end (the left end in FIG. 2) of the positive electrode collector 50 has a through hole 50h. The lower end of the shaft portion 31a of the positive electrode terminal 30 is inserted into the through hole 50h of the positive electrode collector 50 and crimped. The positive electrode collector 50 is, for example, made of aluminum or an aluminum alloy.

The negative electrode collector 60 is a member that electrically connects the negative electrode tab 24t and the negative electrode terminal 40. The negative electrode collector 60 is, for example, a plate-shaped conductive member. As shown in FIG. 2, the negative electrode collector 60 extends along the inner surface of the case body 12 (here, the inside of the second surface 12b) in the long side direction of the second surface 12b. The negative electrode tab 24t (here, a group of negative electrode tabs) is connected to one end (the left end in FIG. 2) of the negative electrode collector 60. In addition, the other end (the right end in FIG. 2) of the negative electrode collector 60 has a through hole 60h. The lower end of the negative electrode terminal 40 is inserted into the through hole 60h of the negative electrode collector 60 and crimped. The negative electrode collector 60 is, for example, made of copper or a copper alloy.

Various insulating members are used in the electric storage device 100. For example, as shown in FIG. 2, an external insulating member 91 is disposed between the positive electrode second conductive member 32 of the positive electrode terminal 30 and the second surface 12b, and between the negative electrode second conductive member 42 of the negative electrode terminal 40 and the second surface 12b, on the outside of the case 10. Also, a gasket 92 is disposed between the positive electrode first conductive member 31 and the second surface 12b, and between the negative electrode first conductive member 41 and the second surface 12b, on the outside of the case 10. Also, an internal insulating member 93 is disposed between the positive electrode collector 50 and the second surface 12b, and between the negative electrode collector 60 and the second surface 12b, on the inside of the case 10. The gasket 92 insulates the case body 12 from the positive electrode terminal 30 and the negative electrode terminal 40, and has the function of sealing (closing) the through holes 18 and 19.

The external insulating member 91, the gasket 92, and the internal insulating member 93 may be made of a material with excellent chemical resistance and weather resistance. The gasket 92 and the internal insulating member 93 may be made of an electrically insulating and elastically deformable resin material, such as a fluorinated resin such as perfluoroalkoxy fluorine resin (PFA), polyphenylene sulfide resin (PPS), or aliphatic polyamide. The gasket 92 and the internal insulating member 93 may be integrated, for example, by insert molding.

The electrode body 20 is a power generating element of the power storage device 100 having a positive electrode 22 and a negative electrode 24. FIG. 4 is a schematic diagram of the electrode body 20 according to the first embodiment. As shown in FIG. 4, the electrode body 20 is a wound electrode body in which a long sheet-like positive electrode 22 and a long sheet-like negative electrode 24 are wound in the sheet longitudinal direction LD with a separator 23 interposed therebetween. The electrode body 20 can be produced, for example, by winding the positive electrode 22, the negative electrode 24, and the separator 23 to form a cylindrical body and press-molding the cylindrical body. The electrode body 20 has a flat shape and has a pair of wide surfaces 20a (see FIGS. 2 and 3). The number of electrode bodies 20 arranged inside one case body 12 is not particularly limited as long as it is plural. As shown in FIG. 3, four electrode bodies 20 are arranged inside the case body 12 here.

2 and 3, the electrode body 20 is housed in the case body 12 so that the wide surface 20a of the electrode body 20 faces the first surface 12a. In this embodiment, the winding axis WL of the electrode body 20 is substantially parallel to the first surface 12a, the third surfaces 12d and 12e, and the sealing plate 14, and is substantially perpendicular to the second surfaces 12b and 12c. The wide surface 20a of the electrode body 20 faces the first surface 12a and the sealing plate 14. One end surface of the electrode body 20 faces the second surface 12b, and the other end surface faces the second surface 12c. Here, the end surface of the electrode body 20 is a laminated surface of the positive electrode 22, the negative electrode 24, and the separator 23, and is an open surface. The electrode body 20 may be housed inside the case 10 in a state where it is covered with an electrode body holder (not shown) made of an insulating resin sheet.

As shown in FIG. 4, the positive electrode 22 has a long strip-shaped positive electrode current collector foil 22c (e.g., aluminum foil) and a positive electrode active material layer 22a fixed to at least one surface of the positive electrode current collector foil 22c. Although not particularly limited, a protective layer 22p may be provided on one side edge portion in the winding axis direction WD of the positive electrode 22 as necessary. Note that, as the constituent materials of the positive electrode active material layer 22a and the protective layer 22p, those used in this type of electricity storage device (in this embodiment, a lithium ion secondary battery) may be used without any particular restrictions.

A plurality of positive electrode tabs 22t are provided at one end (upper end in FIG. 4) of the positive electrode collector foil 22c in the winding axis direction WD. The plurality of positive electrode tabs 22t protrude toward one end (upper end in FIG. 5) of the winding axis direction WD. The plurality of positive electrode tabs 22t are provided at intervals (intermittently) along the longitudinal direction LD of the positive electrode 22. The positive electrode tabs 22t are part of the positive electrode collector foil 22c, and are a portion of the positive electrode collector foil 22c where the positive electrode active material layer 22a is not formed (active material layer unformed portion). In the embodiment shown in FIG. 4, a protective layer 22p is provided on the base end side of the positive electrode tab 22t. In this embodiment, the plurality of positive electrode tabs 22t protrude in the winding axis direction WD beyond the separator 23. The shape and size of the positive electrode tabs 22t can be appropriately adjusted depending on the formation position, etc., taking into account the state of being connected to the positive electrode terminal 30, for example. The positive electrode tabs 22t are stacked at one end of the winding axis direction WD (the upper end in FIG. 4) to form a positive electrode tab group. Therefore, the height of each positive electrode tab 22t (the length in the winding axis direction WD) and the width of each positive electrode tab 22t (the length in the longitudinal direction LD) do not have to be the same.

As shown in FIG. 4, the negative electrode 24 has a long strip-shaped negative electrode current collector foil 24c (e.g., copper foil) and a negative electrode active material layer 24a fixed to at least one surface of the negative electrode current collector foil 24c. Note that the material constituting the negative electrode active material layer 24a may be any material used in this type of power storage device (in this embodiment, a lithium ion secondary battery) without any particular restrictions.

A plurality of negative electrode tabs 24t are provided at one end (upper end in FIG. 4) of the negative electrode collector foil 24c in the winding axis direction WD. The plurality of negative electrode tabs 24t protrude toward one end (upper end in FIG. 4) of the winding axis direction WD. The plurality of negative electrode tabs 24t are provided at intervals (intermittently) along the longitudinal direction LD of the negative electrode 24. The negative electrode tabs 24t are part of the negative electrode collector foil 24c, and are portions of the negative electrode collector foil 24c where the negative electrode active material layer 24a is not formed (active material layer unformed portion). In this embodiment, the plurality of negative electrode tabs 24t protrude in the winding axis direction WD beyond the separator 23. The shape and size of the negative electrode tabs 24t can be appropriately adjusted depending on the formation position, etc., taking into account the state of connection to the negative electrode terminal 40, for example. For example, multiple negative electrode tabs 24t are stacked at one end of the winding axis direction WD (the upper end in FIG. 4) to form a negative electrode tab group. Therefore, the height of each negative electrode tab 24t (the length in the winding axis direction WD) and the width of each negative electrode tab 24t (the length in the longitudinal direction LD) do not have to be the same.

Here, the power storage device 100 has a so-called top tab structure in which the positive electrode tab 22t and the negative electrode tab 24t are located above the electrode body 20. However, the power storage device 100 may have a so-called side tab structure in which the positive electrode tab 22t and the negative electrode tab 24t are provided on the left and right sides of the electrode body 20.

The separator 23 is a member that insulates the positive electrode active material layer 22a of the positive electrode 22 from the negative electrode active material layer 24a of the negative electrode 24. In this embodiment, the separator 23 constitutes the outer surface of the electrode body 20. As the separator 23, for example, a porous sheet made of a resin such as a polyolefin resin such as polyethylene (PE) or polypropylene (PP) is used.

As shown in FIG. 4, in the electrode body 20, the bottom end P3 of the separator 23 is the lowest, followed by the bottom end P2 of the negative electrode 24, and the bottom end P1 of the positive electrode 22 is the highest. The widths of the sheets (in FIG. 4, the length in the winding axis direction WD, excluding the positive electrode tab 22t and the negative electrode tab 24t) are largest in the order of the separator 23, the negative electrode 24, and the positive electrode 22.

The electric storage device 100 disclosed herein is characterized by having a heat dissipation member 70 and a metal joint 80. FIG. 5 is a perspective view showing the heat dissipation member 70 according to the first embodiment. FIG. 6 is a perspective view showing the back surface of the heat dissipation member 70 according to the first embodiment. FIG. 7 is a schematic diagram illustrating the arrangement of the heat dissipation member 70 according to the first embodiment in the case body 12. For ease of explanation, the electrode body 20 is not illustrated in FIG. 7. The heat dissipation member 70 here has a heat dissipation plate 72 and a first side wall 74. The heat dissipation plate 72 and the first side wall 74 may be formed by integral molding, or may be formed by welding or the like.

The heat sink 72 is a member that dissipates heat generated by the electrode body 20. The heat sink 72 has an area that overlaps with the wide surface 20a of the electrode body 20 in the stacking direction. The heat sink 72 is arranged in contact with the wide surface 20a of the electrode body 20. Here, as shown in FIG. 3, the surface of the heat sink 72 that faces the sealing plate 14 contacts one of the wide surfaces 20a of the electrode body 20 that is arranged second from the front. On the other hand, the surface of the heat sink 72 that faces the first surface 12a contacts one of the wide surfaces 20a of the electrode body 20 that is arranged third from the front. This contact allows the heat generated in the electrode body 20 to be conducted to the heat dissipation member 70 through the heat sink 72. Here, the separator 23 that constitutes the outer surface of the electrode body 20 abuts against the heat sink 72.

In some preferred embodiments, the surface of the heat sink 72 has ribs 85. As shown in FIG. 5 and FIG. 6, here, the ribs 85 are arranged in a comb-like shape on the front and back surfaces of the heat sink 72. Here, the ribs 85 have a plurality of protrusions 86 and a plurality of recesses 87. The plurality of protrusions 86 and the plurality of recesses 87 are arranged at intervals from each other. With this configuration, the outside air can be brought into contact with the wide surface 20a of the electrode body 20 through the recesses 87, so that the heat dissipation efficiency can be further improved. The ribs 85 may be on one side of the heat sink 72 or on both sides. Here, as shown in FIG. 5, the ribs 85 are arranged on the surface of the heat sink 72 facing the opening. And, as shown in FIG. 6, the ribs 85 are also arranged on the surface of the heat sink 72 facing the first surface 12a. This makes it possible to more suitably improve the heat dissipation efficiency of the electrode body 20. However, the ribs 85 are not essential, and the heat sink 72 may be flat with no irregularities on its surface.

The first side wall 74 is a member that conducts heat from the heat dissipation member 70 to the case body 12. The first side wall 74 extends from one end of the heat dissipation plate 72 along the inner surface of the case 10 toward the opening 12h. Here, the heat dissipation member 70 has a first side wall 74 (74c, 74d, 74e). As shown in FIG. 3, the first side wall 74c extends toward the opening 12h while contacting the inner surface of the second surface 12c. Although not shown, the first side wall 74d extends toward the opening 12h while contacting the inner surface of the third surface 12d, and the first side wall 74e extends toward the opening 12h while contacting the inner surface of the third surface 12e. By such contact, the heat of the heat dissipation member 70 can be conducted through the first side wall 74 to the second surface 12c, the third surface 12d, and the third surface 12e. As in the heat dissipation member 70 in the first embodiment, it is preferable that the first side wall 74 is disposed along the third surface 12d, 12e and the second surface 12c (i.e., the surface that does not have the through holes 18, 19). This allows a larger contact area between the first side wall 74 and the case 10 to be secured, so that the heat of the heat dissipation member 70 can be more suitably conducted to the case 10. However, it is sufficient that the heat dissipation member 70 has the first side wall 74 that extends along (is in contact with) at least one of the second surface 12c, the third surface 12d, and 12e. Even in such a case, the effect of the present disclosure can be achieved.

Here, the first side wall 74 is flat. However, this is not limited thereto, and for example, if the inner surface of the case body 12 has irregularities or the like, the shape of the first side wall 74 may be changed to match the shape of the inner surface of the case body 12. This allows the first side wall 74 and the inner surface of the case body 12 to be in contact with each other in an optimal manner, and allows the heat of the heat dissipation member 70 to be conducted to the case body 12 in an optimal manner. Because the case body 12 has a wide rectangular opening 12h, the heat dissipation member 70 can be disposed inside the case body 12 even if the first side wall 74 is not flat.

The material of the heat dissipation member 70 may be a metal with high thermal conductivity, such as aluminum or stainless steel (SUS). In particular, it is preferable that the material is the same as that of the case body 12, from the viewpoint of favorably configuring the metal joint 80 described below. Furthermore, the dimensions of the heat dissipation member 70 need only be such that the heat dissipation member 70 can be accommodated inside the case body 12 and the first side wall can be in contact with the inner surface of the case body 12.

As shown in FIG. 3, here, the heat dissipation member 70 is disposed in the center of the case 10 when viewed in the thickness direction of the power storage device 100. In other words, when viewed in the thickness direction of the power storage device 1, the number of electrode bodies 20 (here, two) disposed in front of the heat dissipation plate 72 is the same as the number of electrode bodies 20 (here, two) disposed behind the heat dissipation plate 72. This allows the heat generated from the electrode bodies 20 to be dissipated more evenly. However, this is not limited thereto, and the heat dissipation member 70 may be disposed such that both surfaces (i.e., the front and back surfaces) of the heat dissipation plate 72 are in contact with the wide surface 20a of the electrode body 20 (in other words, the heat dissipation plate 72 is disposed between the multiple electrode bodies 20).

3 and 7, the electric storage device 100 has a metal joint 80. The metal joint 80 is a joint between the first side wall 74 of the heat dissipation member 70 and the case 10. As shown in FIG. 3, the metal joint 80 is formed so as to penetrate the first side wall 74 in the wall thickness direction of the first side wall 74 (here, downward direction) and reach the case 10 (case body 12). The metal joint 80 is formed continuously or intermittently. As shown in FIG. 7, the metal joint 80 is formed intermittently here, and joins the first side wall 74c and the second surface 12c, the first side wall 74d and the third surface 12d, and the first side wall 74e and the third surface 12e, respectively. The electric storage device 100 according to this embodiment has the metal joint 80, so that the heat of the heat dissipation member 70 can be more efficiently conducted to the case 10 through the first side wall 74. This can improve the heat dissipation efficiency of the power storage device 100. The metal joint 80 can be formed, for example, by welding (e.g., laser welding, electron beam welding, resistance welding, etc.), with laser welding being preferably used.

When the heat dissipation member 70 has multiple first side walls 74, it is preferable to form a metal joint 80 on all of the first side walls 74. This allows the heat of the heat dissipation member 70 to be conducted to the case 10 more efficiently through the first side walls 74. However, this is not limited, and it is sufficient that the metal joint 80 is formed on at least one of the first side walls 74. In this case as well, the heat dissipation effect of the electricity storage device 100 can be improved.

As described above, the case body 12 of the present disclosure has a wide rectangular opening 12h, unlike the case used in the conventional technology (see Patent Documents 1 and 2). Therefore, the heat dissipation member 70 as described above can be easily arranged (housed) inside the case body 12. In addition, by having the opening 12h as described above, the irradiation distance of the laser light (the shortest distance from the laser head to the metal joint 80) can be shortened when the metal joint 80 is formed. This makes it possible to suppress the scattering of spatter when the metal joint 80 is formed. In addition, even if spatter occurs, it is easy to collect the spatter. Therefore, according to the electricity storage device 100 disclosed here, it is possible to improve the heat dissipation efficiency of the electricity storage device 100 while suitably suppressing the intrusion of foreign matter inside the case body 12.

Second Embodiment
Fig. 8 is a view of an electricity storage device 200 according to the second embodiment, corresponding to Fig. 3. Fig. 9 is a perspective view showing a heat dissipation member 270 according to the second embodiment. As shown in Fig. 8, the electricity storage device 200 disclosed herein may be similar to the electricity storage device 100 according to the first embodiment described above, except that the heat dissipation member 270 is provided instead of the heat dissipation member 70.

9, the heat dissipation member 270 includes a heat dissipation plate 272 instead of the heat dissipation plate 72, a first side wall 274 (274c, 274d, 274e) instead of the first side wall 74 (74c, 74d, 74e), and a second side wall 276 (276c, 276d, 276e). The material of the heat dissipation member 270 and its location within the case 10 may be the same as those of the heat dissipation member 70 of the first embodiment. The configuration of the heat dissipation plate 272 and the first side wall 274 may be the same as those of the heat dissipation member 70 of the first embodiment, so a detailed description will be omitted.

The second side wall 276 is a member that extends from one end of the heat sink 272 along the inner surface of the case 10 toward the first surface 12a (here, toward the rear). As shown in FIG. 8, the second side wall 276c extends toward the first surface 12a while contacting the inner surface of the second surface 12c. Similarly, the second side wall 276d extends toward the first surface 12a while contacting the inner surface of the third surface 12d, and the second side wall 276e extends toward the first surface 12a while contacting the inner surface of the third surface 12e, respectively, although not shown in the figures. By providing the second side wall 276, the ground contact area between the heat sink 270 and the case 10 can be made wider. Therefore, the heat of the heat sink 270 can be more suitably conducted to the case 10. As shown in FIG. 8, the second side wall 276 does not have a metal joint 80 formed thereon, while the first side wall 274 (here, the first side wall 274c) has a metal joint 80 formed thereon.

8 and 9, here, the heat dissipation member 270 is line-symmetrical in the thickness direction (X direction) of the heat dissipation plate 272. More specifically, the first side wall 274 (274c, 274d, 274e) and the second side wall 276 (276c, 276d, 276e) of the heat dissipation member 270 are arranged to be line-symmetrical with the heat dissipation plate 272 as the axis of symmetry. This makes it unnecessary to distinguish between the front and rear of the heat dissipation member 270 during the manufacture of the power storage device 200. This makes it possible to provide the power storage device 200 more efficiently. Note that "line symmetry" in the technology disclosed herein also includes cases where the line is substantially symmetrical, for example, with an error within the range of dimensional tolerances.

<Method of Manufacturing Electricity Storage Device 100>
As another aspect of the technology disclosed herein, a method for manufacturing the power storage device 100 is provided. The method for manufacturing the power storage device 100 is characterized by performing an electrode assembly housing step, a heat dissipation member arrangement step, and a heat dissipation member welding step using the case 10 and the heat dissipation member 70 as described above. The manufacturing method disclosed herein may further include other steps at any stage, and the other manufacturing processes may be similar to conventional ones. Fig. 10 is a flow diagram showing a method for manufacturing the power storage device 100 according to one embodiment. In this embodiment, the electricity storage device 100 can be manufactured by preparing the case 10 (case body 12 and sealing plate 14) as described above, a plurality of electrode bodies 20 (four electrode bodies 20 in this embodiment), a heat dissipation member 70, an electrolyte, a positive electrode terminal 30, and a negative electrode terminal 40, and by a manufacturing method that typically includes, in this order, an electrode body accommodating process S10, a heat dissipation member arranging process S20, a heat dissipation member welding process S30, a sputter recovery process S40, a tab joining process S50, a sealing plate sealing process S60, and a liquid injection process S70.

(Electrode body accommodation step S10)
In the electrode body accommodation step S10, the electrode body 20 is accommodated in the case body 12. At this time, the electrode body 20 is accommodated in the case body 12 so that the wide surface 20a of the electrode body 20 faces the first surface 12a. In the manufacturing method of the electric storage device 100 disclosed herein, the electrode body accommodation step S10 can be performed in a plurality of steps. In this embodiment, the electrode body accommodation step is performed for two of the four electrode bodies 20. Thereafter, the electrode body accommodation step is performed for the remaining two electrode bodies 20 through the heat dissipation member arrangement step S20, the heat dissipation member welding step S30, the sputter recovery step S40, and the tab joining step S50. In addition, it is preferable to attach the positive electrode terminal 30, the negative electrode terminal 40, the positive electrode current collector 50, the negative electrode current collector 60, and various insulating members to the second surface 12b of the case body 12 prior to the electrode body accommodation step S10.

(Heat dissipation member arrangement step S20)
In the heat dissipation member arrangement step S20, the heat dissipation member 70 is arranged inside the case body 12. At this time, the heat dissipation member 70 is arranged so that the heat dissipation plate 72 contacts the wide surface 20a of any one of the electrode bodies 20 housed in the case body 12, the first side wall 74 contacts the inner surfaces of the second surface 12c and/or the third surfaces 12d, 12e, and the end of the first side wall 74 faces the opening 12h (see FIG. 7).

In some preferred embodiments, in the heat dissipation member placement step S20, a heat dissipation member 270 can be used instead of the heat dissipation member 70. The heat dissipation member 270 is line-symmetrical in the thickness direction of the heat dissipation plate 272. Therefore, when the heat dissipation member 270 is used, as described above, it is not necessary to distinguish between the front and rear of the heat dissipation member 270. Therefore, the heat dissipation member placement step S20 can be easily performed.

(Heat dissipation member welding process S30)
In the heat dissipation member welding step S30, the first side wall 74 of the heat dissipation member 70 is welded to the inner surfaces of the second surface 12c and/or the third surfaces 12d, 12e of the case body 12. The heat dissipation member welding step S30 is performed after the heat dissipation member arrangement step S20. For example, in the heat dissipation member welding step S30, a laser is irradiated onto the first side wall 74 in a state in which the first side wall 74 of the heat dissipation member 70 (more specifically, the outer surface of the first side wall 74) is in contact with the inner surface of the case body 12. This forms the metal joint 80 as described above.

In the heat dissipation member welding process S30, it is preferable to form the metal joint 80 while pressing the first side wall 74 against the inner surface of the case 10. In detail, the first side wall 74 is pressed against the wall portion of the first side wall 74 where the metal joint 80 is to be formed, so that the first side wall 74 and the case body 12 (second surface 12c, third surface 12d, third surface 12e) that contacts the first side wall 74 are in close contact with each other. While maintaining this state, the first side wall 74 is irradiated with a laser to form the metal joint 80. As a result, the first side wall 74 and the case body 12 are joined by the metal joint 80 in a state of being in close contact with each other. Therefore, the heat of the heat dissipation member 70 can be more suitably conducted to the case 10. That is, the provision of the electric storage device 100 with improved heat dissipation efficiency is realized. Note that there are no particular limitations on the means for pressing the first side wall 74 and the jig used for the pressing operation, as long as they do not interfere with welding.

(Sputter recovery step S40)
In some preferred embodiments, a sputter recovery step S40 can be performed. In the sputter recovery step S40, a conventionally known method, such as a suction mechanism, can be adopted. The case body 12 used in this embodiment has a wide rectangular opening 12h. This allows the sputter inside the case 10 to be preferably recovered, and the electricity storage device 100 can be manufactured with more preferably reduced foreign matter contamination.

(Tab joining process S50)
In the tab joining step S50, the positive electrode tabs 22t and the positive electrode collector 50, and the negative electrode tabs 24t and the negative electrode collector 60 are electrically joined. As a result, the electrode body 20 is electrically connected to the positive electrode terminal 30 and the negative electrode terminal 40 through the positive electrode collector 50 and the negative electrode collector 60. The joining means used in the tab joining step S50 may be a conventionally known means, and for example, laser welding or the like may be adopted. In this embodiment, after the tab joining step S50, the electrode body accommodation step S10 is performed for the electrode body 20 to be disposed on the opening 12h side (front side) of the heat sink 72 in the thickness direction (X direction) of the case main body 12.

(Sealing plate sealing step S60)
In the sealing plate sealing step S60, the opening 12h of the case body 12 is sealed with the sealing plate 14. More specifically, the sealing plate 14 is fitted into the opening 12h of the case body 12, and the sealing plate 14 is joined to the edge of the opening 12h of the case body 12 to seal the opening 12h. In the sealing plate sealing step S60, the case body 12 and the sealing plate 14 are preferably welded together. The welding of the case body 12 and the sealing plate 14 can be performed by, for example, laser welding or the like.

(Pouring step S70)
In the liquid injection step S70, the electrolyte is injected into the case 10 through the liquid injection hole 16. Thereafter, the liquid injection hole 16 is closed with a sealing member 16a to hermetically seal the case 10. In this manner, the electricity storage device 100 can be manufactured.

The power storage device 100 can be used for various purposes, but is suitable for use in applications where a large capacity is required, typically as a power source (driving power source) for motors mounted on various vehicles, such as passenger cars and trucks. The type of vehicle is not particularly limited, but examples include plug-in hybrid vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

Although several embodiments of the technology disclosed herein have been described above, the above embodiments are merely examples. The technology disclosed herein can be implemented in various other forms. The technology disclosed herein can be implemented based on the contents disclosed in this specification and the technical common sense in the relevant field. The technology described in the claims includes various modifications and variations of the above-exemplified embodiments. For example, it is possible to replace part of the above-mentioned embodiments with other modified forms, and it is also possible to add other modified forms to the above-mentioned embodiments. Furthermore, if a technical feature is not described as essential, it can also be deleted as appropriate.

<Modification>
For example, in the heat dissipation member 270 according to the second embodiment, the first side wall 274 (274c, 274d, 274e) and the second side wall 276 (276c, 276d, 276e) of the heat dissipation member 270 are arranged to be linearly symmetrical with the heat dissipation plate 272 as the axis of symmetry. However, this is not limited to this. FIG. 11 is a perspective view showing a heat dissipation member 370 according to a modified example. The heat dissipation member 370 includes a heat dissipation plate 372 instead of the heat dissipation plate 272, a first side wall 374 instead of the first side wall 274, and a second side wall 376 instead of the second side wall 276. As shown in FIG. 11, the configurations of the heat dissipation plate 372 and the first side wall 374 are similar to those of the heat dissipation member 270, but the second side wall 376 of the heat dissipation member 370 has a second side wall 376c extending from one side of the heat dissipation member 370. In other words, the second side wall 376 of the heat dissipation member 370 does not have a side wall corresponding to the second side walls 276d, 276e of the heat dissipation member 270. Therefore, the heat dissipation member 370 as described above is not line-symmetric in the thickness direction (X direction) of the heat dissipation plate 372. Even in such a case, the heat dissipation effect of the electricity storage device 100 can be improved.

As described above, specific aspects of the technology disclosed herein include those described in the following sections.
Item 1: An electric storage device comprising: an electrode body having a positive electrode and a negative electrode, the electrode body having a pair of opposing wide surfaces; a hexahedral case housing a plurality of the electrode bodies, the case having a wide rectangular first surface and an opening opposing the first surface, a pair of opposing second surfaces extending from a periphery of the first surface toward the opening, and a pair of opposing third surfaces extending from an outer edge of the first surface toward the opening; and a wide rectangular sealing plate that seals the opening and faces the first surface; and a heat dissipation member housed in the case, wherein the heat dissipation member comprises a heat dissipation plate arranged in contact with the wide surface of the electrode body, and a first side wall extending from one end of the heat dissipation plate along an inner surface of the case toward the opening, and the heat dissipation member has a metal joint that joins the first side wall to the second surface and/or the third surface of the case.
Item 2: The energy storage device according to item 1, further comprising a terminal electrically connected to the electrode body and a through hole through which the terminal is inserted in only one of the second surfaces, and the first side wall is arranged along the inner surface of the third surface and the second surface that does not have the through hole.
Item 3: The power storage device according to item 1 or 2, wherein the heat dissipation member further has a second side wall extending from one end of the heat dissipation plate along the inner surface of the case toward the first surface.
Item 4: The electricity storage device according to any one of Items 1 to 3, wherein a surface of the heat sink has ribs.
Item 5: The electricity storage device according to item 3 or 4, wherein the heat dissipation member is line-symmetric in a thickness direction of the heat dissipation plate.
Clause 6: A heat dissipation member comprising: an electrode body having a positive electrode and a negative electrode, the electrode body having a pair of opposing wide surfaces; a hexahedral case housing a plurality of the electrode bodies, the case having a wide rectangular first surface and an opening opposing the first surface, a pair of opposing second surfaces extending from a periphery of the first surface toward the opening, and a pair of opposing third surfaces extending from a periphery of the first surface toward the opening; and a wide rectangular sealing plate sealing the opening and opposing the first surface; a heat dissipation plate; and a first side wall extending from one end of the heat dissipation plate along an inner surface toward the opening. a heat dissipation member arranging step of arranging the heat dissipation member so that the wide surface of the electrode body is in contact with the first surface and the heat dissipation plate is in contact with the wide surface of any one of the electrode bodies and the first side wall is in contact with an inner surface of the second surface and/or the third surface and an end of the first side wall faces the opening; and a heat dissipation member welding step of welding the first side wall to the inner surface of the second surface and/or the third surface after the heat dissipation member arranging step.
Item 7: The method for producing an electricity storage device according to item 6, further comprising a sputter recovery step of recovering sputters after the heat dissipation member welding step.
Item 8: The method for manufacturing an electricity storage device according to item 6 or 7, wherein the heat dissipation member welding step is performed while pressing the first side wall against an inner surface of the case.
Item 9: The method for manufacturing an electricity storage device according to any one of Items 6 to 8, wherein the electricity storage device further has a terminal electrically connected to the electrode body and a through hole through which the terminal is inserted in only one of the second surfaces, and in the heat dissipation member arrangement process, the first side wall is arranged along the inner surface of the third surface and the second surface that does not have the through hole, and in the heat dissipation member welding process, welding is performed on all surfaces of the first side wall.
Item 10: The method for manufacturing an electricity storage device according to any one of Items 6 to 9, wherein the heat dissipation member is line-symmetric when viewed in a thickness direction of the heat dissipation plate.

10 Case 12 Case body 12a First surface 12b, 12c Second surface 12d, 12e Third surface 12h Opening 14 Sealing plate 18, 19 Through hole 20 Electrode body 22 Positive electrode 22t Positive electrode tab 23 Separator 24 Negative electrode 24t Negative electrode tab 30 Positive electrode terminal 40 Negative electrode terminal 70, 270, 370 Heat dissipation member 72, 272, 372 Heat dissipation plate 74, 274, 374 First side wall 76, 276, 376 Second side wall 80 Metal joint 85 Rib 86 Convex portion 87 Concave portion 92 Gasket 93 Internal insulating member 100, 200 Electric storage device

Claims (10)

An electrode body including a positive electrode and a negative electrode, the electrode body having a pair of opposing wide surfaces;
a hexahedral case housing a plurality of the electrode bodies, the case having a case body having a wide rectangular first surface and an opening facing the first surface, a pair of facing second surfaces extending from a periphery of the first surface toward the opening, and a pair of facing third surfaces extending from an outer edge of the first surface toward the opening; and a wide rectangular sealing plate that seals the opening and faces the first surface;
A heat dissipation member housed in the case;
A power storage device comprising:
Here, the wide surface of the electrode body faces the first surface of the case,
The heat dissipation member is
a heat sink disposed in contact with the broad surface of the electrode body;
a first side wall extending from one end of the heat sink along an inner surface of the case toward the opening,
a metal joint portion that joins the first side wall to the second surface and/or the third surface of the case;
Energy storage device. A terminal electrically connected to the electrode body;
a through hole through which the terminal is inserted in only one of the second surfaces,
the first side wall is disposed along the third surface and an inner surface of the second surface not having the through hole;
The power storage device according to claim 1 . the heat dissipation member further includes a second side wall extending from one end of the heat dissipation plate along an inner surface of the case toward the first surface.
The electricity storage device according to claim 1 or 2. The heat sink has ribs on its surface.
The electricity storage device according to claim 1 or 2. The heat dissipation member is line-symmetrical in the thickness direction of the heat dissipation plate.
The electricity storage device according to claim 3 . An electrode body including a positive electrode and a negative electrode, the electrode body having a pair of opposing wide surfaces;
a hexahedral case housing a plurality of the electrode bodies, the case having a case body having a wide rectangular first surface and an opening facing the first surface, a pair of facing second surfaces extending from a periphery of the first surface toward the opening, and a pair of facing third surfaces extending from a periphery of the first surface toward the opening; and a wide rectangular sealing plate that seals the opening and faces the first surface;
a heat dissipation member including a heat dissipation plate and a first side wall extending from one end of the heat dissipation plate along an inner surface toward the opening;
A method for manufacturing an electricity storage device comprising:
an electrode body accommodating step of accommodating the electrode body in the case main body such that the wide surface and the first surface of the electrode body face each other;
a heat dissipation member arrangement process for arranging the heat dissipation member such that the heat dissipation plate is in contact with the wide surface of any one of the electrode bodies, the first side wall is in contact with an inner surface of the second surface and/or the third surface, and an end of the first side wall faces the opening;
a heat dissipation member welding step of welding the first side wall to an inner surface of the second surface and/or the third surface after the heat dissipation member arrangement step;
A method for manufacturing an electricity storage device comprising the steps of: The method further includes a sputter recovery step of recovering sputters after the heat dissipation member welding step.
The method for producing the electricity storage device according to claim 6 . The heat dissipation member welding step is performed while pressing the first side wall against the inner surface of the case.
A method for producing the electricity storage device according to claim 6 or 7. The power storage device includes a terminal electrically connected to the electrode body;
a through hole through which the terminal is inserted in only one of the second surfaces,
In the heat dissipation member arranging step, the first side wall is arranged along the third surface and an inner surface of the second surface not having the through hole,
In the heat dissipation member welding step, welding is performed on all surfaces of the first side wall.
A method for producing the electricity storage device according to claim 6 or 7. The heat dissipation member is line-symmetrical when viewed in the thickness direction of the heat dissipation plate.
A method for producing the electricity storage device according to claim 6 or 7.

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