Power storage device and power storage module

Abstract

To provide a new power storage device with excellent cooling efficiency at a central part.SOLUTION: A power storage device 100 includes: a battery case having a long side wall; and a cooling medium flow path 70 that is integrally or additionally provided on the long side wall of the battery case. When a flow path 70 is divided into three equal parts in a long side direction Y of the long side wall and divided into a pair of end parts Ae and a central part Am, an inlet IF of the flow path 70 is provided at least at the central part Am, an outlet OF of the flow path 70 is provided at each of the pair of end parts Ae, and a central part flow path 70m that flows in from the inlet IF at the central part Am to the end part Ae is longer than an end part flow path 70e that flows in from the side of the central part Am at the end part Ae to the outlet OF.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a power storage device and a power storage module.

Background Art

[0002] Conventionally, in power sources for vehicle driving and the like, in order to increase the capacity and output, a power storage module formed by electrically connecting a plurality of power storage devices has been widely used. Generally, when the power storage device generates heat and becomes excessively hot during charging and discharging, or when there is a temperature variation in the power storage devices within the power storage module, the inherent power storage performance may not be exhibited. As related prior art documents, Patent Documents 1 to 3 can be cited.

[0003] For example, Japanese Patent Application Laid-Open No. 2011-192642 discloses a power storage module including a plurality of power storage devices arranged along a predetermined arrangement direction, and a cooling member disposed between side walls of adjacent power storage devices in the arrangement direction and having a flow path through which a cooling medium can flow. Japanese Patent Application Laid-Open No. 2011-192642 describes that the power storage device can be efficiently cooled by the cooling member, and the variation in the performance of the power storage device can be suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in recent large-sized power storage devices, the length of the long side of the side wall has become longer, and the central portion in the long side direction has become particularly difficult to cool. Therefore, there is a problem that heat tends to accumulate in the central portion in the long side direction, and temperature unevenness tends to occur in the long side direction. Therefore, according to the study by the present inventor, there is still room for improvement in the above technology.

[0006] The present invention has been made in view of the above circumstances, and its main object is to provide a new power storage device excellent in cooling efficiency of the central portion.

Means for Solving the Problems

[0007] According to the present invention, there is provided a power storage device including a battery case having a substantially rectangular bottom wall having a long side and a short side, a pair of long side walls extending from the long side of the bottom wall and facing each other, a flow path of a cooling medium provided integrally or detachably on the long side wall of the battery case, and an electrode body housed in the battery case. When the flow path is divided into three equal parts in the long side direction of the long side wall and divided into a pair of end portions and a central portion, the inlet of the flow path is provided at least in the central portion, the outlets of the flow path are provided at the pair of end portions respectively, and the central portion flow path flowing in from the inlet in the central portion and reaching the end portion is longer than the end portion flow path flowing in from the central portion side at the end portion and reaching the outlet.

[0008] According to the present invention, by disposing the inlet of the cooling medium at the central portion in the long side direction and disposing the outlets of the cooling medium at the pair of end portions respectively, the central portion can be preferentially cooled. Further, by lengthening the flow path at the central portion in the long side direction and allowing the cooling medium to stay relatively longer than at the end portions, the central portion where heat tends to accumulate can be effectively cooled. With the above effects combined, the cooling efficiency of the central portion can be improved. As a result, temperature unevenness in the long side direction can be reduced.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

[0010] Hereinafter, preferred embodiments of the technology disclosed herein will be described with reference to the drawings as appropriate. Matters other than those specifically mentioned in this specification and necessary for the implementation of the present invention (for example, general configurations and manufacturing processes of power storage devices that do not characterize the present invention) can be grasped as design matters of those skilled in the art based on the prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common general knowledge in the relevant field. In the following drawings, members and parts having the same function are denoted by the same reference numerals, and redundant descriptions may be omitted or simplified. In this specification, the notation "A to B" indicating a range includes the meaning of "greater than A" and "less than B" in addition to the meaning of "A or more and B or less".

[0011] [Power Storage Module] FIG. 1 is a perspective view schematically showing a power storage module 500 according to an embodiment. The power storage module 500 includes, here, a plurality of power storage devices 100 and a restraint mechanism 300. The power storage module 500 does not have a cooling member as described in Japanese Patent Application Laid-Open No. 2011-192642 here. However, as also described in the modifications described later, the power storage module 500 may further include other members such as a cooling member.

[0012] In the following description, reference numerals L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, upper, and lower, respectively, and reference numerals X, Y, and Z in the drawings represent the short-side direction (thickness direction), the long-side direction orthogonal to the short-side direction, and the up-down direction orthogonal to the short-side direction and the long-side direction of the power storage device 100, respectively. The short-side direction X is also the arrangement direction of the power storage devices 100. The up-down direction is preferably the vertical direction. However, these are merely directions for convenience of explanation and do not limit the installation form of the power storage module 500 in any way.

[0013] The restraint mechanism 300 is a member that restrains a plurality of power storage devices 100. The restraint mechanism 300 is configured to apply a specified restraint load to a plurality of power storage devices 100 from the arrangement direction X. Here, the restraint mechanism 300 includes a pair of end plates 310, a pair of side plates 320, and a plurality of screws 330. The end plates 310 and the side plates 320 are preferably made of metal respectively. However, it may have a portion made of resin in part.

[0014] The pair of end plates 310 are arranged at both ends of the power storage module 500 in the arrangement direction X. The pair of end plates 310 sandwich a plurality of power storage devices 100 in the arrangement direction X. The pair of side plates 320 bridge the pair of end plates 310. The pair of side plates 320 are fixed to the end plates 310 by a plurality of screws 330 such that the restraint load is, for example, about 3 to 15 kN, preferably about 5 to 10 kN. Thereby, a restraint load is applied to a plurality of power storage devices 100 from the arrangement direction X, and the power storage module 500 is integrally held. However, the configuration of the restraint mechanism is not limited to this. The restraint mechanism 300 may include, for example, a plurality of restraint bands, binding bars, etc. instead of the side plates 320 and the plurality of screws 330.

[0015] The power storage device 100 is a device capable of repeated charging and discharging. In this specification, the "power storage device" is a concept that includes so-called secondary batteries such as lithium-ion secondary batteries and nickel-metal hydride batteries, and capacitors such as lithium-ion capacitors and electric double-layer capacitors. As shown in FIG. 1, a plurality of power storage devices 100 are arranged here between a pair of end plates 310 along the arrangement direction X (in other words, the thickness direction X of the power storage device 100). Note that the shape, size, number, arrangement, etc. of the plurality of power storage devices 100 are not limited to the embodiments disclosed in FIG. 1 and can be changed as appropriate.

[0016] Although not shown here, when the power storage module 500 is used, a plurality of power storage devices 100 are electrically connected to each other by a conductive member such as a bus bar. The connection method is not particularly limited, and may be, for example, series, parallel, or multi-series multi-parallel. In some embodiments, a plurality of power storage devices 100 are connected in series. In the case of series connection, deterioration of the performance of some of the power storage devices 100 is likely to lead to deterioration of the performance of the entire power storage module 500. Therefore, it is particularly effective to apply the technology disclosed herein.

[0017] FIG. 2 is a perspective view schematically showing the power storage device 100. As can be seen from FIGS. 1 and 2, the plurality of power storage devices 100 are all flat rectangular shapes and are of the same shape here. The plurality of power storage devices 100 are arranged in the arrangement direction X such that the long side walls 12b of the battery case 10 described later face each other. The power storage devices 100 adjacent to each other in the arrangement direction X have their long side walls 12b in contact (in direct contact) here. However, for example, as also described in the modified example described later, when another member such as a cooling member is interposed between the power storage devices 100 adjacent to each other in the arrangement direction X, it may be in contact with the other member.

[0018] FIG. 3 is a schematic longitudinal sectional view taken along line III-III of FIG. 2. As shown in FIG. 3, the power storage device 100 includes a battery case 10, an electrode body 20, a positive electrode terminal 30, a negative electrode terminal 40, and a flow path 70 (see FIG. 2). The power storage device 100 further includes a non-aqueous electrolyte (not shown) here. The power storage device 100 is configured such that the electrode body 20 and the non-aqueous electrolyte are accommodated in the battery case 10 to which the positive electrode terminal 30 and the negative electrode terminal 40 are attached and in which the flow path 70 is integrally or additionally provided. The power storage device 100 is a non-aqueous electrolyte secondary battery here, for example, a lithium ion secondary battery.

[0019] The electrode body 20 may be the same as the conventional one and is not particularly limited. Here, the electrode body 20 is a wound electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are laminated via a strip-shaped separator and wound around a winding axis. The electrode body 20 has a flat outer shape. Here, the electrode body 20 is disposed inside the battery case 10 in a direction in which the winding axis is substantially parallel to the long side direction Y. However, in other embodiments, the electrode body 20 may be disposed inside the battery case 10 in a direction in which the winding axis is substantially parallel to the vertical direction Z. Further, the electrode body 20 may be a laminated electrode body in which a plurality of square (typically rectangular) positive electrodes and a plurality of square (typically rectangular) negative electrodes are stacked in an insulated state.

[0020] Although not shown, the electrode body 20 may be accommodated inside the battery case 10 in a state covered with a resin insulating sheet (electrode body holder). Also, the number of electrode bodies 20 disposed inside one battery case 10 may be one or two or more (plural). A positive electrode tab group 23 is attached to the positive electrode of the electrode body 20 and is electrically connected to the positive electrode terminal 30 via a positive electrode current collector 50. A negative electrode tab group 25 is attached to the negative electrode of the electrode body 20 and is electrically connected to the negative electrode terminal 40 via a negative electrode current collector 60.

[0021] The non-aqueous electrolyte may be the same as the conventional one and is not particularly limited. The non-aqueous electrolyte typically contains a non-aqueous solvent and a supporting salt (electrolyte salt, such as a Li salt or a Na salt). The non-aqueous electrolyte is typically liquid, but may also be gel-like. In other embodiments, the power storage device 100 may be provided with a solid electrolyte instead of the non-aqueous electrolyte. In that case, the separator can also be omitted.

[0022] The battery case 10 is a housing that houses the electrode body 20 and the non-aqueous electrolyte. As shown in FIG. 2, the battery case 10 here has an outer shape that is flat, bottomed, and substantially rectangular parallelepiped (rectangular). The material of the battery case 10 may be the same as the conventional one and is not particularly limited. The battery case 10 is preferably made of metal, and more preferably made of, for example, an iron alloy such as iron or stainless steel, aluminum, or an aluminum alloy. Among them, from the viewpoint of improving safety, a metal with a melting point of 1000 ° C or higher, and further 1200 ° C or higher is preferable, and in particular, an iron alloy, for example, stainless steel containing chromium and / or nickel is preferable. Note that the iron or iron alloy may be nickel-plated.

[0023] As shown in FIG. 3, the battery case 10 includes a case body 12 having an opening 12h and a sealing plate (lid body) 14 that seals the opening 12h. As shown in FIG. 2, the case body 12 includes a bottom wall 12a, a pair of long side walls 12b, and a pair of short side walls 12c. The bottom wall 12a is here substantially rectangular with a long side and a short side. The bottom wall 12a faces the sealing plate (lid body) 14. The bottom wall 12a is flat. In the present specification, the term "substantially rectangular" includes not only a perfect rectangular shape (rectangular shape), but also, for example, a shape in which the corners connecting the long side and the short side of the rectangular shape are R-shaped, or a shape having a notch at the corner.

[0024] The pair of short side walls 12c extend from the short sides of the bottom wall 12a. The pair of short side walls 12c are arranged facing each other and connect the bottom wall 12a and the sealing plate 14. The short side walls 12c are flat plates. The pair of long side walls 12b extend from the long sides of the bottom wall 12a. The pair of long side walls 12b are arranged facing each other and connect the bottom wall 12a and the sealing plate 14. The long side walls 12b are flat plates.

[0025] The long side walls 12b are preferably made of metal as described above. For example, it is more preferably made of an iron alloy such as iron, stainless steel, aluminum, an aluminum alloy, etc. Among them, an iron alloy is preferable, and stainless steel containing chromium and / or nickel is more preferable. Generally, iron or an iron alloy has a lower thermal conductivity than conventionally widely used aluminum and is difficult to use for the long side walls 12b. However, according to the technology disclosed herein, such a material with a low thermal conductivity can also be suitably used.

[0026] Here, the long side walls 12b are substantially rectangular having a long side (the side in the long side direction Y in FIG. 2) and a short side (the side in the vertical direction Z in FIG. 2). The length of the long side walls 12b in the long side direction Y is preferably 150 mm or more, more preferably 200 mm or more, and even more preferably 250 mm or more. Generally, the longer the length of the long side walls 12b in the long side direction Y, the more likely heat is to accumulate near the center in the long side direction Y (for example, the central part Am in FIG. 4), and temperature unevenness is likely to occur. Therefore, applying the technology disclosed herein is particularly effective. The length of the long side walls 12b in the long side direction Y may be, for example, 1000 mm or less, 500 mm or less. Thereby, the effects of the technology disclosed herein can be exerted at a high level. The long side walls 12b are preferably horizontally long. That is, it is preferable that the length in the long side direction Y is longer than the length in the vertical direction Z. The length of the long side walls 12b in the vertical direction Z is preferably 100 mm or more.

[0027] In plan view, the area of the long side walls 12b is larger than the area of the short side walls 12c. Although not particularly limited, in the case of a high-capacity type power storage device 100 used for in-vehicle use, etc., the area of the long side walls 12b is generally 10000 mm2 Preferably, it is as above, 15000 mm 2 Above is preferable, 20000 mm 2 More preferably, it is above, 25000 mm 2 Even more preferably, it is above, 30000 mm 2 Particularly preferably, it is above. When the area of the long side wall 12b is large in this way, it is particularly effective to apply the technology disclosed herein. Also, from the viewpoint of exhibiting the effects of the technology disclosed herein at a high level, the area of the long side wall 12b is generally 150000 mm 2 Below, 100000 mm 2 Below is preferable.

[0028] The long side wall 12b has a uniform thickness here. Although not particularly limited, the thickness of the long side wall 12b is preferably generally 0.1 to 2 mm, more preferably 0.2 to 1 mm, and even more preferably 0.4 to 0.8 mm, from viewpoints such as mechanical strength, rigidity, durability, etc. The thickness of the long side wall 12b may be the same as the thickness of the short side wall 12c, or may be thicker than the thickness of the short side wall 12c, for example, by the amount where the flow path 70 (groove portion) described later is formed.

[0029] As shown in FIG. 3, the sealing plate 14 is attached to the case body 12 so as to close the opening 12h of the case body 12. The sealing plate 14 faces the bottom wall 12a of the case body 12. The sealing plate 14 is substantially rectangular in plan view. The battery case 10 is integrated by joining (preferably by welding) the sealing plate 14 to the periphery of the opening 12h of the case body 12. The battery case 10 is hermetically sealed.

[0030] The sealing plate 14 is provided with a discharge valve 17 and two terminal lead-out holes 18, 19. The discharge valve 17 is configured to break when the pressure inside the battery case 10 reaches a predetermined value or more and discharge the gas inside the battery case 10 to the outside. The terminal lead-out holes 18, 19 penetrate the sealing plate 14 in the vertical direction Z.

[0031] The positive terminal 30 is electrically connected to the positive tab group 23 of the electrode body 20 via the positive current collector 50 inside the battery case 10. The positive terminal 30 extends from the inside to the outside of the sealing plate 14 through the terminal lead-out hole 18. The positive terminal 30 is disposed at one end (the left end in FIGS. 2 and 3) in the long side direction Y of the sealing plate 14. Here, the positive terminal 30 is caulked to the peripheral portion surrounding the terminal lead-out hole 18 of the sealing plate 14 by caulking. The positive terminal 30 is fixed to the sealing plate 14.

[0032] The negative terminal 40 is electrically connected to the negative tab group 25 of the electrode body 20 via the negative current collector 60 inside the battery case 10. The negative terminal 40 extends from the inside to the outside of the sealing plate 14 through the terminal lead-out hole 19. The negative terminal 40 is disposed at the other end (the right end in FIGS. 2 and 3) in the long side direction Y of the sealing plate 14. Here, the negative terminal 40 is caulked to the peripheral portion surrounding the terminal lead-out hole 19 of the sealing plate 14 by caulking. The negative terminal 40 is fixed to the sealing plate 14.

[0033] The flow path 70 is a flow path for a cooling medium provided integrally or additionally on the long side wall 12b of the battery case 10. The cooling medium is, for example, air (wind). As shown in FIG. 2, the flow path 70 is a groove portion (recess) provided in the long side wall 12b here and is provided integrally with the long side wall 12b. Although not shown, the flow path 70 is provided on a pair of long side walls 12b here, respectively. The depth of the groove portion may vary depending on the thickness of the long side wall 12b and the heat generation property of the power storage device 100, and thus is not particularly limited, but can be set to approximately 1 mm to 50 mm, for example, about 1 to 20 mm. However, as also described in the modification example to be described later, the flow path 70 only needs to be arranged so as to contact the long side wall 12b, and may be provided, for example, in a cooling member 80 separate from the battery case 10.

[0034] FIG. 4 is a side view schematically showing a flow path 70 provided in the long side wall. In the present embodiment, as shown in FIG. 4, when the flow path 70 is divided into three equal parts in the long side direction Y of the long side wall 12b and divided into a pair of end portions Ae and a central portion Am, the inlet IF of the flow path 70 is provided at least in the central portion Am, and the outlet OF of the flow path 70 is provided in each of the pair of end portions Ae. By providing the inlet IF in the central portion Am and bringing the cooling medium (for example, air) AF flowing in from the inlet IF into contact with the central portion Am first, the central portion Am can be preferentially cooled.

[0035] The inlet IF is provided here below in the vertical direction Z (on the side of the bottom wall 12a). Since the cooling medium AF flowing through the flow path 70 is typically heated by the heat of the power storage device 100 and rises, providing the inlet IF vertically downward makes it easier to smoothly circulate a large amount of the cooling medium AF. The number of inlets IF is one here. This makes it easier to adjust the residence time of the cooling medium AF in the central portion Am. However, as described in a modification example to be described later, the number of inlets IF may be plural. The inlet IF is provided only in the central portion Am here and not in the end portion Ae. This can more effectively cool the central portion Am. However, as described in a modification example to be described later, in addition to the central portion Am, the inlet IF may also be provided in the end portion Ae.

[0036] The outlets OF are provided here on the sides in the long side direction Y (on the side of the pair of short side walls 12c), respectively. For each end portion Ae, the number of outlets OF is preferably plural. This makes it easier to shorten the residence time of the cooling medium AF in the end portion Ae. Note that the flow path 70 in FIG. 4 is merely an example, and the number, arrangement, width, shape, etc. of the inlets IF and outlets OF are not limited to the aspects disclosed in FIG. 4 and can be appropriately changed.

[0037] The flow path 70 has a central flow path 70m that flows in from the inlet IF at the central part Am and reaches the end part Ae, and a pair of end flow paths 70e that flow in from the central part Am side at the end part Ae and reach the outlet OF. It is preferable that the pair of end flow paths 70e have line symmetry with respect to the center line in the long side direction Y. In the technology disclosed herein, the length Lm (not shown) of the central flow path 70m is longer than the length Le (not shown) of the end flow path 70e. That is, Le < Lm. By making the flow path longer at the central part Am and retaining the cooling medium AF for a longer time than at the end part Ae, the central part Am where heat tends to accumulate can be effectively cooled. Thereby, the cooling efficiency of the central part Am can be enhanced. In addition, since the cooling medium AF that has absorbed the heat of the central part Am in the central flow path 70m flows into the end flow path 70e, the temperature unevenness in the long side direction Y can be reduced.

[0038] In addition, in the present embodiment, at the central part Am, the length of the route reaching one end part Ae and the length of the route reaching the other end part Ae are different. In this case, the average length of the two routes is defined as the "length Lm of the central flow path 70m". Also, in the present embodiment, at one end part Ae, the flow path that has flowed in from the central part Am side branches, and there are a plurality of routes reaching the outlet OF. In this case, the average length of all the routes is defined as the "length Le of the end flow path 70e". The length Le of the end flow path 70e is substantially the same as the length in the long side direction Y at the end part Ae here.

[0039] The length Lm of the central flow path 70m is preferably 2 times or more, more preferably 3 times or more, still more preferably 4 times or more, and particularly preferably 5 times or more the length Le of the end flow path 70e. Thereby, the residence time of the cooling medium AF at the central part Am can be lengthened, and the effects of the technology disclosed herein can be exerted at a higher level. The length Lm of the central flow path 70m may be 100 times or less, 50 times or less the length Le of the end flow path 70e.

[0040] The central flow path 70m has a labyrinth structure here. The labyrinth structure includes at least one bent shape (or curved shape) and is a flow path (snake path) that meanders within the central flow path 70m. Thereby, the residence time of the cooling medium AF in the central part Am is lengthened, and the effects of the technology disclosed herein can be exerted at a higher level. The central flow path 70m communicates with the end flow path 70e, specifically the inflow part e1 described later, on the end Ae side (left and right in FIG. 4).

[0041] The end flow path 70e has, here, from the upstream side, one inflow part e1, one manifold part e2, and a plurality of straight parts e3. The inflow part e1 communicates with the downstream end of the central flow path 70m and is the part where the cooling medium AF flows in from the central flow path 70m. The inflow part e1 extends along the long side direction Y. The inflow part e1 extends linearly over the entire length. The manifold part e2 communicates with the downstream end of the inflow part e1 and is the part where the cooling medium AF flows in from the inflow part e1. The straight part e3 communicates with the downstream end of the manifold part e2 and is the part where the cooling medium AF flows in from the manifold part e2.

[0042] The manifold part e2 is interposed between the central flow path 70m and the plurality of straight parts e3, specifically, between the inflow part e1 and the plurality of straight parts e3. The manifold part e2 is a space where the cooling medium stays and is a part for uniformly distributing the cooling medium AF flowing in from the inflow part e1 to the plurality of straight parts e3. By having the manifold part e2, the cooling medium AF can be distributed in a well-balanced manner in the vertical direction Z, and temperature unevenness in the vertical direction Z can be reduced. The manifold part e2 is semi-circular here. However, the shape of the manifold part e2 is not particularly limited and may be, for example, rectangular or trapezoidal.

[0043] The straight part e3 extends along the long side direction Y and constitutes a flow path leading to the outlet OF. The straight part e3 extends linearly over the entire length. The straight part e3 extends on the shortest route from the manifold part e2 to the outlet OF. By having the straight part e3, it becomes easier to shorten the residence time of the cooling medium AF at the end Ae.

[0044] Note that the flow path 70 (here, the groove portion) can be formed in the long side wall 12b by a conventionally known processing method, such as press working, die casting, forging, casting, photolithography, laser processing, or the like.

[0045] In the power storage module 500 as described above, as shown by the arrow in FIG. 4, the cooling medium (for example, air) AF flows into the flow path 70 from the inlet IF provided below the central portion Am. The cooling medium AF that has flowed into the flow path 70 flows through the flow path 70 to cool the power storage device 100 and is discharged from the outlet OF provided on the side of the end portion Ae. According to the air-cooled cooling system that uses air as the cooling medium AF, the power storage device 100 can be cooled at low cost.

[0046] The power storage module 500 can be used for various applications. Since it has excellent cooling efficiency even for a large-sized power storage device 100, it can be suitably used, for example, as a power source (driving power source) for a motor mounted on a vehicle such as a passenger car or a truck. The type of the vehicle is not particularly limited, and examples include a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), and a battery electric vehicle (BEV).

[0047] As described above, the preferred embodiments of the present invention have been described, but the above embodiments are merely examples. The present invention can be implemented in various other forms. The present invention can be implemented based on the content disclosed in this specification and the common general knowledge in the art. The technology described in the claims includes various modifications and changes of the above-exemplified embodiments. For example, it is possible to replace a part of the above-described embodiments with other modified examples, and it is also possible to add other modified examples to the above-described embodiments. Also, if the technical feature is not described as essential, it can be appropriately deleted.

[0048] For example, in the embodiment of FIG. 4 described above, the number of inlets IF of the flow path 70 was one, and no inlet IF was provided at the end portion Ae. Further, the central flow path 70m had a labyrinth structure. However, it is not limited to this. FIG. 5 is a diagram corresponding to FIG. 4 according to the first modification. As shown in FIG. 5, the flow path 170 may have a plurality of inlets IF. The inlets IF may be provided at the central portion Am and the end portion Ae, respectively. In this case, it is preferable that the number of inlets IF provided at the central portion Am is larger than the number of inlets IF provided at the end portion Ae. In the present embodiment, the number of inlets IF and the number of outlets OF are the same.

[0049] Further, in the flow path 170, the central flow path 170m includes a first flow path m1, a second flow path m2, a third flow path m3, a first connecting flow path mc1, and a second connecting flow path mc2. The first flow path m1 has a first straight portion that extends linearly along the vertical direction Z (a direction intersecting the long side direction Y) from the first inlet IF, a bent portion that bends toward the end flow path 70e side at the upper end of the first straight portion, and a second straight portion that extends linearly toward the end 10e side along the long side direction Y from the bent portion. The second flow path m2 and the third flow path m3 each have, similarly to the first flow path m1, a first straight portion that extends linearly along the vertical direction Z from the second to third inlets IF, a bent portion, and a second straight portion that extends linearly toward the end 10e side along the long side direction Y from the bent portion.

[0050] The first connecting flow path mc1 is bridged between the first flow path m1 and the second flow path m2 adjacent to each other in the long side direction Y so as to form a ladder shape, and communicates the first flow path m1 and the second flow path m2 with each other. Similarly, the second connecting flow path mc2 is bridged between the second flow path m2 and the third flow path m3 adjacent to each other in the long side direction Y so as to form a ladder shape, and communicates the second flow path m2 and the third flow path m3 with each other. Therefore, for example, the cooling medium AF flowing into the second flow path m2 from the second inlet IF is diverted to the first flow path m1 and the third flow path m3 by the first connecting flow path mc1 and the second connecting flow path mc2. Thereby, the residence time of the cooling medium AF at the central portion Am can be increased.

[0051] For example, in the embodiment of FIG. 2 described above, the positive electrode terminal 30 and the negative electrode terminal 40 were attached to a single sealing plate 14 (the same surface of the battery case 10). However, it is not limited to this. FIG. 6 is a diagram corresponding to FIG. 2 according to the second modification. As shown in FIG. 6, in the second modification, the power storage device 200 includes a battery case 110. The battery case 110 includes, here, a rectangular tube-shaped case body 112 having a pair of openings at both ends in the long side direction Y, and two sealing plates 114 that close the pair of openings of the case body 112. The case body 112 is formed, for example, by bending a single metal plate into a tubular shape and joining (for example, welding) the seams. Here, the welding joint 112d is located on the upper surface of the case body 112. The battery case 110 is integrated by joining the sealing plates 114 to the peripheries of the pair of openings of the case body 112, respectively.

[0052] Similar to the embodiment of FIG. 2, the case body 112 has a pair of long side walls 112b having, for example, a flow path 70 (groove portion) as shown in FIG. 4. The positive electrode terminal 130 and the negative electrode terminal 140 are respectively fixed to two sealing plates 114 (opposing surfaces of the battery case 110) here. Specifically, the positive electrode terminal 30 is attached to the sealing plate 114 disposed on one side in the long side direction Y. The negative electrode terminal 40 is attached to the sealing plate 114 disposed on the other side in the long side direction Y. The technology disclosed herein can also be preferably applied to such a power storage device 200.

[0053] For example, in the embodiment of FIG. 1 described above, the power storage module 500 did not have a cooling member. Also, the flow path 70 was a groove portion (recess) integrally provided on the long side wall 12b of the battery case 10. However, it is not limited to this. FIG. 7 is a diagram corresponding to FIG. 1 according to the third modification. As shown in FIG. 7, the power storage module 500a according to the third modification includes a plurality of power storage devices 100a, a cooling member 400, and a restraint mechanism 300. The cooling member 400 is disposed between the plurality of power storage devices 100a in the arrangement direction X. That is, in the arrangement direction X, the power storage devices 100a and the cooling member 400 are arranged alternately. In this case, the flow path 70 may be provided in the cooling member 400. Specifically, the flow path 70 may be provided on the surface of the cooling member 400 that faces the long side wall 12b of the battery case 10. In other words, the flow path 70 may be provided in an attached manner to the long side wall 12b of the battery case 10. The long side wall 12b of the battery case 10 may not be provided with the flow path 70.

[0054] In some embodiments, the cooling member 400 is preferably made of a metal with high thermal conductivity. For example, it is more preferably made of an iron alloy such as iron or stainless steel, aluminum, an aluminum alloy, etc. Among them, an iron alloy is preferred, and stainless steel containing chromium and / or nickel is more preferred. Also, in some other embodiments, the cooling member 400 is preferably made of resin, and more preferably made of, for example, polypropylene (PP), polyphenylene sulfide (PPS), etc. The length of the cooling member 400 in the long side direction Y is preferably substantially the same as that of the long side wall 12b of the battery case 10. The length of the cooling member 400 in the vertical direction Z is preferably substantially the same as that of the long side wall 12b of the battery case 10.

[0055] As described above, specific aspects of the technology disclosed herein include those described in the following items. Item 1: A power storage device comprising: a battery case having a substantially rectangular bottom wall with a long side and a short side, and a pair of long side walls extending from the long side of the bottom wall and facing each other; a flow path for a cooling medium provided integrally or attached to the long side walls of the battery case; and an electrode body housed in the battery case. When the flow path is divided into three equal parts in the long side direction of the long side wall and divided into a pair of end portions and a central portion, the inlet of the flow path is provided at least in the central portion, the outlets of the flow path are provided at the pair of end portions respectively, and the central flow path flowing in from the inlet in the central portion and reaching the end portion is longer than the end flow path flowing in from the central portion side at the end portion and reaching the outlet. Item 2: The power storage device according to Item 1, wherein the length of the central flow path is 2 times or more the length of the end flow path. Item 3: The power storage device according to Item 1 or Item 2, wherein the length in the long side direction of the long side wall is 150 mm or more. Item 4: The power storage device according to any one of Items 1 to 3, wherein the central flow path has a labyrinth structure. Item 5: The power storage device according to any one of Items 1 to 4, wherein the end flow path extends along the long side and has a straight portion reaching the outlet. Item 6: The power storage device according to Item 5, wherein the end flow path has a manifold portion which is a space where the cooling medium stays between the central flow path and the straight portion. Item 7: The power storage device according to any one of Items 1 to 3, wherein the central flow path has a first flow path and a second flow path extending along a direction intersecting the long side, and a connecting flow path connecting the first flow path and the second flow path. Item 8: The power storage device according to any one of Items 1 to 7, wherein the flow path is a groove provided on the long side wall of the battery case. Item 9: A power storage module in which a plurality of the power storage devices according to any one of Items 1 to 7 are combined such that the long side walls face each other. Item 10: The power storage module according to Item 9, further comprising a cooling member disposed between the long side walls of adjacent power storage devices, and the flow path is provided in the cooling member.

Explanation of Reference Numerals

[0056] 10, 110 Battery case 12, 112 Case body 12b, 112b Long side wall 14, 114 Sealing plate 20 Electrode body 70, 170 Flow path 100, 100a, 200 Energy storage device 300 Restraint mechanism 400 Cooling member 500, 500a Energy storage module

Claims

1. A battery case having a substantially rectangular bottom wall with a long side and a short side, and a pair of long side walls extending from the long side of the bottom wall and facing each other; A cooling medium flow path provided integrally or attached to the long side wall of the battery case; An electrode body housed in the battery case; Comprising: When the flow path is divided into three equal parts in the long side direction of the long side wall and divided into a pair of end portions and a central portion, The inlet of the flow path is provided at least in the central portion, The outlets of the flow path are respectively provided at the pair of end portions, The central flow path that flows in from the inlet in the central portion and reaches the end portion is longer than the end flow path that flows in from the central portion side at the end portion and reaches the outlet; A power storage device.

2. The length of the central flow path is 2 times or more the length of the end flow path, The power storage device according to Claim 1.

3. The length in the long side direction of the long side wall is 150 mm or more, The power storage device according to Claim 1 or 2.

4. The central flow path has a labyrinth structure, The power storage device according to Claim 1 or 2.

5. The end flow path extends along the long side and has a straight portion leading to the outlet, The power storage device according to Claim 4.

6. The end flow path has a manifold portion which is a space where the cooling medium stays between the central flow path and the straight portion, The power storage device according to Claim 5.

7. The central flow path: A first flow path and a second flow path extending along a direction intersecting the long side; A connecting flow path connecting the first flow path and the second flow path; Having: The power storage device according to Claim 1 or 2.

8. The flow path is a groove provided on the long side wall of the battery case, The power storage device according to Claim 1 or 2.

9. A power storage module in which a plurality of the power storage devices according to Claim 1 or 2 are combined so that the long side walls face each other.

10. Further comprising a cooling member disposed between the long side walls of adjacent power storage devices, The flow path is provided in the cooling member, The power storage module according to Claim 9.

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