JP2020119808A - Power storage device - Google Patents

Abstract

To provide a power storage device capable of suppressing unevenness in the temperature distribution of an electrode body when charging/discharging is performed.SOLUTION: A power storage device according to the present disclosure includes a housing case 2, an electrode body 3 including an electrode 30 and housed in the housing case 2, an electrolyte accommodated in the housing case 2 and stored in the bottom portion 40 of the housing case 2, an external terminal 8 provided on the outer surface of the housing case 2 and connected to the electrode 30, and an insulating heat transfer member 6 connecting the external terminal 8 and the bottom portion 40 of the housing case 2.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a power storage device.

The power storage device includes a housing case, an electrode body and an electrolytic solution, a positive electrode terminal and a negative electrode terminal. The electrode body and the electrolytic solution are housed in a housing case. A positive electrode and a negative electrode are formed on the electrode body. The electrolytic solution is stored at the bottom of the housing case (Patent Documents 2 to 4).

The positive electrode terminal and the negative electrode terminal are provided on the outer surface of the housing case. The positive electrode terminal is connected to the positive electrode of the electrode body, and the negative electrode terminal is connected to the negative electrode of the electrode body.

The power storage device configured as described above generates heat during charging and discharging. Therefore, in the power storage device described in Japanese Patent Application Laid-Open No. 2002-319388, the radiation performance of the power storage device is improved by providing a radiation fin on the positive electrode terminal and the negative electrode terminal.

JP-A-2002-319388 JP 2012-160338A JP 2012-059361A International Publication No. 2015/186333

In recent years, the amount of current charged and discharged in the power storage device has been increased, and the amount of current flowing through the positive electrode terminal and the negative electrode terminal has increased. Along with this, a large amount of heat is generated at the positive electrode terminal and the negative electrode terminal, and the amount of heat radiation from the heat radiation fins provided at the positive electrode terminal and the negative electrode terminal cannot sufficiently cool the positive electrode terminal and the negative electrode terminal.

When the temperature of the positive electrode terminal or the negative electrode terminal rises, the temperature of the electrode body arranged in the housing case also rises. At this time, the temperature of the portion of the electrode body close to the positive electrode terminal or the negative electrode terminal is likely to be higher than that of the portion away from the positive electrode terminal or the negative electrode terminal.

As described above, when the temperature distribution in the electrode body is uneven, a portion of the electrode body in which the deterioration locally progresses easily occurs.

The present disclosure has been made in view of the above problems, and an object thereof is to provide a power storage device capable of suppressing unevenness in the temperature distribution of the electrode body.

An electricity storage device according to the present disclosure includes a housing case, an electrode body that is housed in the housing case, includes an electrode, an electrolyte solution that is housed in the housing case, and is stored at the bottom of the housing case, and a housing case. An external terminal that is provided on the outer surface of the housing and that is connected to the electrode; and an insulating heat transfer member that connects the external terminal and the bottom of the housing case.

According to the power storage device of the present disclosure, it is possible to suppress unevenness in the temperature distribution of the electrode body.

FIG. 3 is a cross-sectional view showing power storage device 1 according to the present embodiment. FIG. 3 is a side view showing power storage device 1, and is a side view when viewed from side wall 27 side. FIG. 3 is a plan view showing power storage device 1. FIG. 3 is a cross-sectional view showing power storage device 100 with heat transfer members 6 and 7 removed from power storage device 1. FIG. 6 is a cross-sectional view showing a power storage device 1D according to a second embodiment. FIG. 3 is a cross-sectional view showing a connection position of heat transfer members 6 and 7 in power storage device 1. 6 is a graph showing temperature changes in regions R12, R15, and R18 when the connection position of the other ends of the heat transfer members 6 and 7 is set to level A (connection positions A1 and A2) and the current value is set to 100A. FIG. 6 is a cross-sectional view showing power storage device 1 when the connection position of the other ends of heat transfer members 6 and 7 is set to level D (connection positions D1 and D2) and the current value is set to 100A. It is a graph which shows the temperature change in area|region R12, R15, R18, when the connection position of the other end of the heat transfer members 6 and 7 is set to level D (connection position D1, D2), and a current value is set to 100A. FIG. 7 is a cross-sectional view showing a connection position of heat transfer members 71 and 72 in power storage device 1D.

The power storage device according to the present embodiment will be described with reference to FIGS. 1 to 10. Among the configurations shown in FIGS. 1 to 10, the same or substantially the same configurations are designated by the same reference numerals, and the duplicated description will be omitted. Note that, in the structure shown in the embodiment, a structure corresponding to a structure described in a claim may be described in parentheses together with a structure in the claim.

FIG. 1 is a cross-sectional view showing power storage device 1 according to the present embodiment. The power storage device 1 includes a housing case 2, an electrode body 3, an electrolytic solution 4, connection units 5A and 5B, heat transfer members 6 and 7, a positive electrode terminal 8, a negative electrode terminal 9, and insulating members 10 and 11. And spacers 12 and 13 and an insulating sheet 14.

The housing case 2 includes a case body 15 and a lid 16. The case body 15 and the lid 16 are made of, for example, aluminum or aluminum alloy. The case body 15 is formed so as to open upward, and the lid 16 is provided so as to close the opening of the case body 15. The case body 15 is formed in a flat shape and is thin in the thickness direction TD of the power storage device 1.

The case body 15 includes a bottom plate 25 and a peripheral wall 26. The peripheral wall 26 is formed in an annular shape so as to extend upward from the outer peripheral edge portion of the bottom plate 25. The upper side of the peripheral wall 26 extends in a ring shape, and the opening of the case body 15 is formed by the upper side of the ring.

The peripheral wall 26 includes a pair of side walls 27 and 28 and a pair of main walls (not shown). Side wall 27 and side wall 28 are arranged in width direction W of power storage device 1, and a pair of main walls (not shown) are arranged in thickness direction TD.

The positive electrode terminal 8 and the negative electrode terminal 9 are provided on the upper surface side of the lid 16. The positive electrode terminal 8 is made of, for example, aluminum or an aluminum alloy. The positive electrode terminal 8 and the negative electrode terminal 9 are arranged at intervals in the width direction W.

An insulating member 10 is arranged between the positive electrode terminal 8 and the lid 16, and the insulating member 10 insulates between the positive electrode terminal 8 and the lid 16. Similarly, an insulating member 11 is arranged between the negative electrode terminal 9 and the lid 16, and the insulating member 11 insulates between the negative electrode terminal 9 and the lid 16.

The electrode body 3 includes a plurality of positive electrode sheets 20, a plurality of separators 21, and a plurality of negative electrode sheets 22, and the separators 21 are arranged between the positive electrode sheets 20 and the negative electrode sheets 22. The electrode body 3 is a so-called laminated electrode body, but may be a so-called wound electrode body.

The positive electrode sheet 20 includes a plate-shaped current collector and a positive electrode mixture layer formed on the current collector. The collector of the positive electrode sheet 20 is made of aluminum or the like.

The positive electrode mixture layer is formed on at least one of the front and back surfaces of the current collector, and the positive electrode mixture layer contains a positive electrode active material, a conductive material, a binder, and the like. The positive electrode active material may include, for example, at least one selected from the group consisting of lithium cobalt oxide, lithium nickel oxide, lithium manganate, lithium nickel cobalt aluminate, lithium nickel cobalt manganese oxide, and lithium iron phosphate. ..

The current collector of the positive electrode sheet 20 has an uncoated portion where the positive electrode mixture layer is not formed. The separator 21 is a porous film such as a nonwoven fabric.

The negative electrode sheet 22 includes a plate-shaped current collector and a negative electrode mixture layer formed on the current collector. The collector of the negative electrode sheet 22 is, for example, copper. The negative electrode mixture layer contains a negative electrode active material, a binder, and the like. The negative electrode active material is, for example, graphite.

The current collector of the negative electrode sheet 22 has an uncoated portion where the negative electrode mixture layer is not formed.

Here, the electrode body 3 includes a positive electrode 30 and a negative electrode 31. The positive electrode 30 is formed on one end side of the electrode body 3 in the width direction W, and the negative electrode 31 is formed on the other end side in the width direction W. The positive electrode 30 is formed by stacking the uncoated portions of the plurality of positive electrode sheets 20. The negative electrode 31 is formed by stacking uncoated portions of a plurality of negative electrode sheets 22.

The connection units 5A and 5B are housed in the housing case 2. The connection unit 5A electrically connects the positive electrode 30 of the electrode body 3 and the positive electrode terminal 8. The connection unit 5B electrically connects the negative electrode 31 of the electrode body 3 and the negative electrode terminal 9.

The connection units 5A and 5B include current collector plates 35A and 35B and conductive members 36A and 36B. The current collector plate 35A is welded to the positive electrode 30, and the current collector plate 35B is welded to the negative electrode 31. The conductive member 36A electrically connects the current collector plate 35A and the positive electrode terminal 8. The conductive member 36B electrically connects the collector plate 35B and the negative electrode 31.

The current collector plate 35A includes an upper piece 37A and a welding piece 38A extending downward from the upper piece 37A. The welding piece 38A is welded to the positive electrode 30 and is formed so as to extend in the vertical direction. The upper piece 37A is located above the electrode body 3.

The spacer 12 is arranged between the upper piece 37A and the lid 16, and the conductive member 36A ensures insulation between the upper piece 37A and the lid 16.

The conductive member 36A is formed so as to extend upward from the upper surface of the upper piece 37A. The conductive member 36A passes through the through hole formed in the lid 16 and is connected to the positive electrode terminal 8.

The insulating member 10 and the spacer 12 are inserted into the through hole formed in the lid 16, and the insulating member 10 and the spacer 12 ensure the insulating properties of the conductive member 36A and the lid 16.

The collector plate 35B is configured similarly to the collector plate 35A, and the collector plate 35B includes an upper piece 37B and a welding piece 38B. The spacer 13 insulates between the upper piece 37B and the lid 16, and the spacer 13 and the insulating member 11 insulate between the conductive member 36B and the lid 16.

The electrolytic solution 4 contains a supporting salt and a solvent. The supporting salt is, for example, LiPF ₆ . The same size includes EC, D1MC, and EMC. In addition, "EC" shows ethylene carbonate. "D1MC" indicates dimethyl carbonate. "EMC" indicates ethyl methyl carbonate.

Therefore, in the example shown in FIG. 1, the bottom portion 40 of the housing case 2 is a portion of the housing case 2 located below the liquid surface 41 of the electrolytic solution 4.

The heat transfer members 6 and 7 are made of a material having an insulating property and a high heat transfer property. For example, the heat transfer members 6 and 7 are made of ceramics such as alumina and silicon carbide. The heat transfer members 6 and 7 have a thermal conductivity of 20 W/m·k or more and a volume resistivity of 10 ⁶ Ω·cm.

The heat transfer member 6 is formed so as to connect the positive electrode terminal 8 and the bottom portion 40. In the example shown in FIG. 1, it is connected to the bottom plate 25 of the housing case 2.

The heat transfer member 6 includes a connection piece 45, a connection piece 46, a fixing member 47, and engaging claws 48 and 49. The connection piece 45 is formed in a plate shape, and one end of the connection piece 45 is connected to the positive electrode terminal 8. The engaging claw 48 is formed on the lower surface of the connecting piece 45 on one end side of the connecting piece 45, and is fitted in the engaging groove formed on the upper surface of the positive electrode terminal 8.

The connection piece 45 passes above the lid 16 and is then bent toward the side wall 27. The connecting piece 45 is formed so as to extend downward from the side wall 27 with a space therebetween. The other end of the connection piece 45 is located substantially at the center of the housing case 2 in the height direction.

One end of the connection piece 46 is connected to the lower end side of the connection piece 45 by the fixing member 47. Specifically, one end side of the connection piece 46 is located closer to the side wall 27 side than the other end side of the connection piece 45, and one end side of the connection piece 46 contacts the surface of the other end side of the connection piece 45. ing.

The connection piece 46 extends downward from the side wall 27 with a space therebetween, and is then bent toward the bottom plate 25 side. The connecting piece 46 is formed so as to extend in contact with the lower surface of the bottom plate 25, and the other end of the connecting piece 46 is located on the lower surface of the bottom plate 25. The engagement claw 49 is formed on the upper surface of the connection piece 46 on the other end side of the connection piece 46. The engaging claw 49 is engaged with an engaging groove formed in the bottom plate 25.

FIG. 2 is a side view showing power storage device 1, and is a side view when viewed from side wall 27 side.
The other end (lower end) of the connection piece 45 is provided so as to overlap the connection piece 46. The connecting piece 45 is formed with a slit 50 extending in the vertical direction on the lower end side of the connecting piece 45.

Similarly, the connection piece 46 is formed with a screw hole on one end side of the connection piece 46. The slit 50 and the screw hole are arranged so as to overlap each other in the width direction W.

The fixing member 47 is, for example, a screw. The fixing member 47 includes a head portion and a shaft portion. The head portion of the fixing member 47 is arranged on the connection piece 45, and the shaft portion of the fixing member 47 is screwed into the screw hole.

Thereby, the connection piece 45 and the connection piece 46 are fixed so as to contact each other, and the connection piece 45 and the connection piece 46 are also thermally connected.

Here, the housing case 2 may be deformed in the vertical direction due to a temperature change. At this time, the connection piece 45 and the connection piece 46 relatively move in the vertical direction away from each other. At this time, the shaft portion of the fixing member 47 can relatively move within the slit 50. In this way, the heat transfer member 6 is formed so as to allow the housing case 2 to be deformed in the vertical direction.

In FIG. 1, the heat transfer member 7 is formed similarly to the heat transfer member 6. The heat transfer member 7 is formed so as to connect the negative electrode terminal 9 and the bottom portion 40 of the housing case 2. The heat transfer member 7 includes a connection piece 55, a connection piece 56, and a fixing member 57. The fixing member 57 connects the lower end side of the connection piece 55 and the upper end side of the connection piece 56. The heat transfer member 7 is also formed so as to allow the accommodation case 2 to be vertically deformed.

The insulating sheet 14 is formed in a bag shape, and is formed so as to open upward. The insulating sheet 14 includes the side portion 32, the side portion 33, and the bottom portion 34.

The side portion 32 of the insulating sheet 14 is arranged between the side wall 27 of the housing case 2 and the electrode body 3 and the connection unit 5A. Similarly, the side portion 33 of the insulating sheet 14 is arranged between the side wall 28 of the housing case 2 and the electrode body 3 and the connection unit 5B. The bottom portion 34 of the insulating sheet 14 is arranged between the electrode body 3 and the bottom plate 25 of the housing case 2.

This suppresses the electrode body 3 and the connection units 5A and 5B from directly contacting the housing case 2.

FIG. 3 is a plan view showing power storage device 1. The positive electrode terminal 8 is formed in a plate shape. A bus bar 60 is connected to the positive electrode terminal 8. Bus bar 60 electrically connects power storage device 1 to a negative electrode terminal of another power storage device 1A adjacent to power storage device 1.

The connection position where the bus bar 60 is connected to the positive electrode terminal 8 is separated from the connection position where the heat transfer member 6 is connected to the positive electrode terminal 8.

Thereby, for example, vibration applied to bus bar 60 can be suppressed from being transmitted to heat transfer member 6.

The negative electrode terminal 9 is formed in a plate shape, and the bus bar 61 is connected to the negative electrode terminal 9. Bus bar 61 connects negative electrode terminal 9 and a positive electrode terminal of a power storage device adjacent to power storage device 1 on the opposite side to power storage device 1A. The connection position where the bus bar 61 is connected to the negative electrode terminal 9 and the connection position where the heat transfer member 7 is connected to the negative electrode terminal 9 are separated from each other.

In the power storage device 1 configured as described above, when charging/discharging is performed, current flows in and out of the electrode body 3 through the positive electrode terminal 8 and the negative electrode terminal 9.

That is, the current is concentrated on the positive electrode terminal 8 and the negative electrode terminal 9, and the positive electrode terminal 8 and the negative electrode terminal 9 generate heat.

Here, a case where the heat transfer members 6 and 7 are not provided will be described. FIG. 4 is a cross-sectional view showing power storage device 100 with heat transfer members 6 and 7 removed from power storage device 1.

As shown in FIG. 4, when the heat transfer members 6 and 7 are not provided, the heat of the positive electrode terminal 8 and the negative electrode terminal 9 is transferred to the electrode body 3 through the connection units 5A and 5B.

Further, the heat of the heat transfer members 6 and 7 is transferred to the lid 16. The heat transferred to the lid 16 is transferred to the side walls 27 and 28.

Here, in the portion of the housing case 2 located above the liquid surface 41, the heat transferred to the side walls 27, 28 is transferred to the electrode body 3 via radiant heat and air.

On the other hand, in the portion of the housing case 2 located below the liquid level 41, the heat from the positive electrode terminal 8 and the negative electrode terminal 9 is cooled by the electrolytic solution 4. Therefore, below the liquid level 41, the heat from the positive electrode terminal 8 and the negative electrode terminal 9 is difficult to be transferred to the electrode body 3.

As a result, in the power storage device in which the heat transfer members 6 and 7 are not provided, the temperature distribution in the electrode body 3 tends to be uneven when the battery is charged and discharged. Here, in the portion of the electrode body 3 where the temperature is high, the deterioration is likely to proceed, and there is a possibility that the deterioration locally progresses in the electrode body 3.

As shown in FIG. 4, it is assumed that the electrode body 3 is divided into regions R1 to R9. The region R1 is located directly below the positive electrode terminal 8, and the region R3 is located directly below the negative electrode terminal 9.

Then, in the power storage device 100, when charging and discharging are repeated with a constant current, the temperatures of the regions R1 and R3 become substantially the same temperature, and the temperatures of the regions R1 and R3 become the highest among the regions R1 to R9.

The region R2 has the second highest temperature after the regions R1 and R3. The region R5 is the next highest after the region R2, and the regions R4 and R6 are the second highest after the region R5. Then, the region R8 becomes the highest next to the regions R4 and R6, and the regions R7 and R9 become the lowest. As described above, in the power storage device 100, it can be seen that the temperature distribution of the electrode body 3 has unevenness.

On the other hand, in FIG. 1, in power storage device 1 according to the present embodiment, positive electrode terminal 8 is connected to heat transfer member 6, and negative electrode terminal 9 is connected to heat transfer member 7. Therefore, the heat of the positive electrode terminal 8 and the negative electrode terminal 9 is also transferred to the heat transfer member 6.

Since the heat transfer member 6 is connected to the bottom 40 of the housing case 2, at least a part of the heat of the positive electrode terminal 8 is transferred to the bottom 40. Similarly, since the heat transfer member 7 is also connected to the bottom portion 40, at least part of the heat of the negative electrode terminal 9 is transferred to the bottom portion 40. When the heat is transferred to the bottom portion 40, it is cooled by the electrolytic solution 4. This can prevent the temperatures of the positive electrode terminal 8 and the negative electrode terminal 9 from rising.

Since at least a part of the heat generated in the positive electrode terminal 8 and the negative electrode terminal 9 is cooled in the bottom portion 40, the heat from the positive electrode terminal 8 and the negative electrode terminal 9 passes through the connection units 5A, 5B and the side walls 27, 28, and the electrodes The amount of heat transferred to the body 3 can be reduced.

Accordingly, in power storage device 1 according to the present embodiment, even if the positive electrode terminal 8 and the negative electrode terminal 9 generate heat due to charge and discharge, it is possible to suppress unevenness in the temperature distribution in electrode body 3. ..

(Embodiment 2)
A power storage device 1D according to the second embodiment will be described with reference to FIG. FIG. 5 is a cross-sectional view showing power storage device 1D according to the second embodiment.

The power storage device 1D includes a housing case 2, an electrode body 3, an electrolytic solution 4, connection units 70A and 70B, heat transfer members 71 and 72, a positive electrode terminal 8, a negative electrode terminal 9, and insulating members 10 and 11. And spacers 12 and 13.

The connection unit 70A includes a current collector plate 73A and a conductive member 74A. The current collecting plate 73A includes a welding piece 75A and an upper piece 76A. The upper piece 76A is arranged on the lower surface side of the spacer 12. The welding piece 75A extends downward from the end side of the upper piece 76A on the negative electrode terminal 9 side, and is welded to the positive electrode 30 of the electrode body 3.

The conductive member 74A is connected to the positive electrode terminal 8 and extends downward, and a screw portion 77A is formed on the lower end side of the conductive member 74A.

The conductive member 74A is inserted into the through hole formed in the upper piece 76A of the current collector plate 73A, and the lower end portion of the conductive member 74A projects below the upper piece 76A.

The heat transfer member 71 includes an upper piece 80 and a connection piece 81. The upper piece 80 is arranged on the lower surface of the upper piece 76A of the current collector 73A.

A screw hole is formed on the upper surface of the upper piece 80 of the heat transfer member 71, and a screw portion 77A formed on the lower end of the conductive member 74A is screwed into the screw hole. As a result, the spacer 12 and the upper piece 76A of the connection unit 70A are fixed between the connection piece 81 and the lid 16.

The connection piece 81 of the heat transfer member 71 is connected to the lower surface of the upper piece 80. Specifically, the connecting piece 81 is connected to a portion of the lower surface of the upper piece 80 located on the side wall 27 side.

The connecting piece 81 is formed so as to pass between the side portion 32 of the insulating sheet 14 and the side wall 27 of the housing case 2 and extend downward. The lower end of the connecting piece 81 is in contact with the side wall 27 of the housing case 2.

The connection piece 81 is made of a material that is elastically deformable and has a high electric resistance, such as alumina. The lower end portion of the connection piece 81 is in pressure contact with the side wall 27 by the elastic force of the connection piece 81.

Here, the contact position P1 of the connection piece 81 and the side wall 27 is located below the liquid surface 41 of the electrolytic solution 4, and the contact position P1 is located at the bottom portion 40.

The heat transfer member 72 is formed similarly to the heat transfer member 71, and the connection unit 70B is configured similarly to the connection unit 70A.

The connection unit 70B includes a current collector plate 73B and a conductive member 74B. The current collector plate 73B includes a welding piece 75B and an upper piece 76B. The upper piece 76B is arranged on the lower surface side of the spacer 13. The welding piece 75B extends downward from the edge of the upper piece 76B on the positive electrode terminal 8 side and is welded to the negative electrode 31 of the electrode body 3. The conductive member 74B is connected to the negative electrode terminal 9 and extends downward, and a screw portion 77B is formed on the lower end side of the conductive member 74B.

The conductive member 74B is inserted into a through hole formed in the upper piece 76B of the current collector plate 73B, and the lower end portion of the conductive member 74B projects below the upper piece 76B.

The heat transfer member 72 includes an upper piece 82 and a connecting piece 83. The upper piece 82 is arranged on the lower surface of the upper piece 76B of the current collector 73B. A screw hole is formed on the upper surface of the upper piece 82 of the heat transfer member 72, and a screw portion 77B formed at the lower end of the conductive member 74B is screwed into the screw hole.

The connection piece 83 of the heat transfer member 72 is connected to a portion of the lower surface of the upper piece 82 located on the side wall 28 side. The connecting piece 83 is formed so as to pass between the side portion 33 of the insulating sheet 14 and the side wall 28 of the housing case 2 and extend downward. The lower end of the connecting piece 83 is also in pressure contact with the side wall 28 by the elastic force of the connecting piece 83.

The contact position P2 of the connection piece 83 and the side wall 28 is located below the liquid level 41 of the electrolytic solution 4, and the contact position P2 is located at the bottom portion 40.

Also in the power storage device 1D configured in this manner, at least part of the heat of the positive electrode terminal 8 and the negative electrode terminal 9 is transferred to the bottom portion 40 and cooled by the electrolytic solution 4.

Accordingly, also in power storage device 1A, it is possible to suppress a part of the temperature of electrode body 3 from rising, and it is possible to suppress unevenness in the temperature distribution of electrode body 3.
(Example 1)
With reference to FIG. 1 and FIG. 6 and the like, the results of various studies on the connection positions between the heat transfer members 6 and 7 and the housing case 2 in the power storage device 1 according to the first embodiment will be described.

In FIG. 1, the positive electrode terminal 8 and the negative electrode terminal 9 are not electrically connected to the housing case 2, and the power storage device 1 is a so-called prismatic secondary battery. The housing case 2 is made of No. 3000 aluminum. The heat transfer member 7 and the positive electrode terminal 8 are made of alumina ceramics.

FIG. 6 is a cross-sectional view showing connection positions of heat transfer members 6 and 7 in power storage device 1. The heat transfer member 6 and the heat transfer member 7 are not shown in FIG. One end of the heat transfer member 6 is connected to the positive electrode terminal 8, and the connection position of the other end of the heat transfer member 6 is variously changed. Similarly, one end of the heat transfer member 7 is connected to the negative electrode terminal 9, and the connection position of the other end of the heat transfer member 7 is variously changed.

In FIG. 6, connection positions A1, B1, C1, D1, and E1 indicate connection positions of the other end of the heat transfer member 6. The connection positions A2, B2, C2, D2, E2 indicate the connection positions of the other end of the heat transfer member 7. The connection position A1 and the connection position A2 have the same height in the height direction. Similarly, the heights of the connection positions B1, C1, D1, and E1 in the height direction are the same as the heights of the connection positions B2, C2, D2, and E2 in the height direction.

Here, “h1” shown in FIG. 6 represents the height of the liquid surface of the electrolytic solution 4, and “h2” represents the height of the upper side of the electrode body 3. “H3” indicates the height position of the upper surface of the lid 16. The connection positions A1 and A2 are located on the lower surface of the bottom plate 25 of the housing case 2.

The connection positions B1 and B2 are located on the outer surfaces of the side walls 27 and 28, and the height of the connection positions B1 and B2 is not more than the height h1.

The connection positions C1 and C2 are located on the outer surfaces of the side walls 27 and 28, and the heights of the connection positions C1 and C2 are higher than the height h1 and not higher than the height h2.

The connection positions D1 and D2 are located on the outer surfaces of the side walls 27 and 28, and the heights of the connection positions D1 and D2 are higher than h2 and lower than h3. The connection positions E1 and E2 are located on the upper surface of the lid 16.

In "Level" of Table 1, "A" shows the case where each end of the heat transfer members 6 and 7 is connected to the connection positions A1 and A2. Similarly, “B” indicates the case where the connection positions B1 and B2 are connected, and “C” indicates the case where the connection positions C1 and C2 are connected. Further, "D" indicates a case where the connection positions D1 and D2 are connected, and "E" indicates a case where the connection positions E1 and E2 are connected.

Then, in an environment of 25° C., charging/discharging was repeatedly performed with the current value kept constant. Further, the current value was divided into three types, and specifically, the current value was set to 50 A, 70 A, and 100 A. Then, it was examined whether temperature unevenness was suppressed in the electrode body 3.

Regarding whether or not the temperature distribution of the electrode body 3 is uneven, as shown in FIG. 6, the electrode body 3 is divided into regions R11 to R19, and charging/discharging is repeated, so that each region R11 to Perform until the temperature of R19 stabilizes. Then, when the difference between the maximum value and the minimum value of the temperature of each of the regions R11 to R19 is ±1° C. or less, “◯” is given, and when the difference is larger than ±1° C., “x” is given.

As shown in Table 1, when the current value is 50 A, the temperature distribution of the electrode body 3 may be uniform regardless of the connection positions of the heat transfer members 6 and 7 of the levels A to E. Do you get it.

It was found that when the current value is 70 A, the temperature distribution of the electrode body 3 does not have unevenness at the connection positions of the heat transfer members 6 and 7 at the levels A, B, and C.

It was found that when the current value was 100 A and the connection positions of the heat transfer members 6 and 7 were levels A and B, there was no unevenness in the temperature distribution of the electrode body 3.

That is, assuming that the height of the connection position of the heat transfer members 6 and 7 is h, when the following formula (1) is satisfied, the effect of the heat transfer members 6 and 7 is large, and the temperature unevenness of the electrode body 3 may occur. It can be effectively suppressed.

0<h≦h1 (1)
When the following expression (2) is satisfied, the effect of the heat transfer members 6 and 7 is recognized to some extent, and the temperature unevenness generated in the electrode body 3 can be suppressed to some extent.

h1<h≦h2 (2)
When the following expression (3) is satisfied, the effect of the heat transfer members 6 and 7 is small, and the temperature unevenness is likely to occur in the electrode body 3.

h2<h≦h3 (3)
That is, it is understood that it is preferable to connect the other ends of the heat transfer members 6 and 7 to the bottom portion 40 of the housing case 2 located at the height h1 or less of the liquid surface 41.

FIG. 7 is a graph showing temperature changes in regions R12, R15, and R18 when the connection position of the other ends of the heat transfer members 6 and 7 is set to level A (connection positions A1 and A2) and the current value is set to 100A. is there. The configuration of power storage device 1 shown in FIG. 1 is a configuration when the connection position of the other ends of heat transfer members 6, 7 is set to level A (connection positions A1, A2).

FIG. 8 is a cross-sectional view showing power storage device 1 when the connection position of the other ends of heat transfer members 6 and 7 is set to level D (connection positions D1 and D2) and the current value is set to 100A.

FIG. 9 is a graph showing temperature changes in regions R12, R15, and R18 when the connection position of the other ends of the heat transfer members 6 and 7 is set to level D (connection positions D1 and D2) and the current value is set to 100A. is there.

7 and 9, “L1” indicates the temperature of the positive electrode terminal 8, and “L2” indicates the temperature of the region R12. “L3” indicates the temperature of the region R15, and “L4” indicates the temperature of the region R18.

As is clear from FIGS. 7 and 9, when the connection position of the other ends of the heat transfer members 6, 7 is set to level A (connection positions A1, A2), the heat transfer members 6, 7 are It can be seen that the temperature unevenness is smaller than when the connection position at the other end is set to level D (connection positions D1 and D2).
(Example 2)
The results of examining the connection positions of the heat transfer members 71 and 72 in the power storage device 1D according to the second embodiment will be described with reference to FIGS. 5 and 10.

In FIG. 5, the positive electrode terminal 8 and the negative electrode terminal 9 are not electrically connected to the housing case 2, and the power storage device 1 is a so-called prismatic secondary battery. The housing case 2 is made of No. 3000 aluminum. The heat transfer members 71 and 72 are made of alumina ceramics.

FIG. 10 is a cross-sectional view showing a connection position of heat transfer members 71 and 72 in power storage device 1D. Specifically, one end of the heat transfer member 71 is connected to the positive electrode terminal 8, and the connection position of the other end of the heat transfer member 71 is variously changed. Similarly, one end of the heat transfer member 72 is connected to the negative electrode terminal 9, and the connection position of the other end of the heat transfer member 72 is variously changed. Note that the heat transfer members 71 and 72 are not shown in FIG.

In FIG. 10, connection positions F1, G1, H1 indicate connection positions of the other end of the heat transfer member 71. The connection positions F2, G2, H2 indicate the connection positions of the other end of the heat transfer member 72.

The height positions of the connection position F1 and the connection position F2 match, and the height positions of the connection position G1 and the connection position G2 match. Similarly, the connection position H1 and the connection position H2 have the same height position.

“H1” indicates the height of the liquid surface of the bottom plate 25, and “h2” indicates the height of the upper side of the electrode body 3. “H3” indicates the height position of the upper surface of the lid 16.

The connection positions F1 and F2 are located on the inner surfaces of the side walls 27 and 28, and the height of the connection positions F1 and F2 is h1 or less.

The connection positions G1 and G2 are located on the inner surfaces of the side walls 27 and 28, and the heights of the connection positions G1 and G2 are higher than h1 and not more than h2.

The connection positions H1 and H2 are located on the inner surfaces of the side walls 27 and 28, and the heights of the connection positions H1 and H2 are higher than h2.

In the "level" of Table 2, "F" shows the case where each end of the heat transfer members 71 and 72 is connected to the connection positions F1 and F2. "G" connects the ends of the heat transfer members 71, 72 to the connection positions G1, G2, and "H" connects the ends of the heat transfer members 71, 72 to the connection positions H1, H2. Indicates.

Then, in an environment of 25° C., charging/discharging was repeatedly performed with the current value kept constant. Further, the current value was divided into three types, and specifically, the current value was set to 50 A, 70 A, and 100 A. Then, it was examined whether temperature unevenness was suppressed in the electrode body 3.

As to whether or not the temperature distribution of the electrode body 3 is uneven, as shown in FIG. 10, the electrode body 3 is divided into regions R21 to R29, and charging/discharging is repeated, whereby each region R21 to Perform until the temperature of R29 stabilizes. Then, when the difference between the maximum value and the minimum value of the temperature of each of the regions R21 to R29 is ±1° C. or less, it is “◯”, and when the difference is larger than ±1° C., it is “x”.

As shown in Table 2, when the current value is 50 A, the temperature distribution of the electrode body 3 may be uniform regardless of the connection positions of the heat transfer members 71 and 72 at any of the levels F to H. Do you get it.

It was found that when the current value is 70 A, the temperature distribution of the electrode body 3 does not have unevenness at the connection positions of the heat transfer members 71 and 72 at the levels F and G.

It has been found that when the current value is 100 A, the temperature distribution of the electrode body 3 does not have unevenness at the connection positions of the heat transfer members 71 and 72 at the levels F and G.

That is, when the height of the connection position of the heat transfer members 71 and 72 is H, when the following formula (1) is satisfied, the effect of the heat transfer members 71 and 72 is great, and the temperature unevenness of the electrode body 3 is generated. It can be effectively suppressed.

0<H≦h1 (1)
When the following expression (2) is satisfied, the effect of the heat transfer members 71 and 72 is recognized to some extent, and the temperature unevenness occurring in the electrode body 3 can be suppressed to some extent.

h1<H≦h2 (2)
When the following expression (3) is satisfied, the effect of the heat transfer members 71 and 72 is small, and the temperature unevenness is likely to occur in the electrode body 3.

h2<H≦h3 (3)
That is, it is understood that the other ends of the heat transfer members 71 and 72 are preferably connected to the bottom portion 40 of the housing case 2 located at the height h1 or less of the liquid surface 41.

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

1, 1A, 1D, 100 Storage device, 2 Housing case, 3 Electrode body, 4 Electrolyte solution, 5A, 5B, 70A, 70B Connection unit, 6, 7, 71, 72 Heat transfer member, 8 Positive electrode terminal, 9 Negative electrode terminal 10, 11 Insulating member, 12, 13 Spacer, 14 Insulating sheet, 15 Case body, 16 Lid, 20 Positive electrode sheet, 21 Separator, 22 Negative electrode sheet, 25 Bottom plate, 26 peripheral wall, 27, 28 Side wall, 30 Positive electrode, 31 Negative electrode , 32, 33 side part, 34, 40 bottom part, 35A, 35B, 73A, 73AB, 73B current collector plate, 36A, 36B, 74A, 74B conductive member, 37A, 37B, 76A, 76B, 80, 82 upper piece, 38A, 38B, 75A, 75B Welding piece, 41 Liquid level, 45, 46, 55, 56, 81, 83 Connecting piece, 47, 57 Fixing member, 48, 49 Engaging claw, 50 Slit, 51 Screw hole, 60, 61 bus bar, 77A, 77B screw part, 2002, 2012 JP, A, B, C, D, E, F, G, H level, A1, A2, B1, B2, C1, C2, D1, D2, E1, E2, F1, F2, G1, G2, H1, H2 connection position, P1, P2 contact position, R1, R2, R3, R4, R5, R6, R7, R8, R9, R11, R12, R15, R18, R19, R21, R29 regions, TD thickness direction, W width direction.

Claims (1)

A storage case,
An electrode body that is housed in the housing case and includes an electrode,
While being stored in the storage case, an electrolyte solution stored in the bottom of the storage case,
An external terminal provided on the outer surface of the housing case and connected to the electrode,
An insulating heat transfer member that connects the external terminal and the bottom portion of the housing case,
A power storage device comprising: