JP2019185927A - Power storage device - Google Patents

Abstract

To provide a power storage device which can uniformize electrode temperature.SOLUTION: A power storage device 10 comprises a power storage module 12 on which a plurality of bipolar electrodes 32 are stacked in one direction via a separator 40, the bipolar electrode 32 including a positive electrode layer 36 on one face of an electrode plate 34 and a negative electrode layer 38 on the other face of the electrode plate 34. The power storage device 10 comprises a conducting body 14 which is laminated in one direction against the power storage module 12 and in contact with the power storage module 12. The conducting body 14 includes a first region R1 positioned on one side in a cross direction intersecting in one direction, and a second region R2 positioned on the other side of the cross direction. The conducting body 14 includes a through-hole 14a which extends in the cross direction and through which a coolant F circulates from the first region R1 side to the second region R2 side, and heat transfer property is lower in the first region R1 than in the second region R2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power storage device.

  As a conventional power storage device, for example, a technique described in Patent Document 1 is known. The power storage device described in Patent Literature 1 includes a plurality of power storage modules in which a plurality of battery elements having sheet-like electrodes are stacked, and a conductor provided between the power storage modules. The conductor has a heat dissipation structure that can dissipate heat generated in the power storage module, and functions as a heat dissipation member.

JP 2009-117105 A

  By the way, as a heat dissipation structure for a conductor, for example, a through hole through which a refrigerant can flow is provided inside the conductor, and the power storage module may be radiated by circulating the refrigerant. However, when the refrigerant is circulated in the through hole in this way, the downstream region is less likely to be cooled than the upstream region, and a temperature difference is generated between the upstream region and the downstream region. As a result, variations in resistance values due to temperature differences occur and current tends to flow only in part of the electrodes, so that the bipolar electrodes are likely to deteriorate.

  An object of the present invention is to provide a power storage device that can achieve uniform temperature of electrodes.

  In a power storage device according to one aspect of the present invention, a plurality of bipolar electrodes in which a positive electrode layer is provided on one surface of an electrode plate and a negative electrode layer is provided on the other surface of the electrode plate are stacked in one direction through a separator. An electrical storage device including the electrical storage module, the electrical storage device including an electrical conductor stacked in one direction with respect to the electrical storage module and disposed in contact with the electrical storage module, wherein the electrical conductor intersects in one direction A first region located on one side of the direction and a second region located on the other side in the cross direction, the conductor extending in the cross direction, from the first region side to the second region side A through-hole through which the refrigerant flows is provided, and the heat transfer in the first region is lower than the heat transfer in the second region.

  In this power storage device, the heat conductivity in the first region of the conductor is lower than the heat conductivity in the second region of the conductor. Thereby, when the refrigerant is circulated in the through hole, the heat exchange between the conductor and the refrigerant in the first region is suppressed compared to the heat exchange between the conductor and the refrigerant in the second region. Therefore, by circulating the refrigerant from the first region side toward the second region side, the temperature rise of the refrigerant in the first region is suppressed, and the refrigerant in a state where sufficient cooling capacity is also maintained in the second region. It can be distributed. As a result, variation in the cooling capacity between the first region and the second region is suppressed, so that the temperature of the bipolar electrode can be made uniform.

  The first region may be provided with a heat exchange suppression unit that suppresses heat exchange between the conductor and the refrigerant. According to this configuration, the heat conductivity in the first region can be adjusted by adjusting the material, shape, and the like of the heat exchange suppression unit.

  The heat exchange suppression part may be formed along the inner wall of the through hole. According to this configuration, while ensuring conductivity between the conductor and the power storage module, heat exchange between the conductor and the refrigerant in the first region can be suppressed, and the temperature of the bipolar electrode can be made uniform. .

  According to the present invention, a power storage device capable of making the temperature of the electrodes uniform is provided.

It is a schematic sectional drawing which shows the electrical storage apparatus which concerns on one Embodiment. It is a schematic sectional drawing which shows the electrical storage module contained in the electrical storage apparatus of FIG. It is a figure which shows roughly the conductor and electrical storage module seen from the lamination direction. It is a fragmentary sectional view which shows roughly the conductor seen from the crossing direction. It is a figure which shows the temperature distribution of a bipolar electrode in case the whole conductor has the substantially the same heat conductivity.

  Hereinafter, various embodiments will be described in detail with reference to the drawings. In addition, in each drawing, the same code | symbol is attached | subjected to the same or an equivalent part, and the overlapping description is abbreviate | omitted. 1 to 4 show an XYZ orthogonal coordinate system.

  The power storage device 10 shown in FIG. 1 is used as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage module 12 is, for example, a bipolar battery. In the following description, a nickel metal hydride secondary battery is illustrated as such a power storage module 12.

  The plurality of power storage modules 12 are stacked via a conductor 14 such as a metal plate to form an array 11. When viewed from the stacking direction (Z direction), the power storage module 12 and the conductor 14 have, for example, a rectangular shape. When viewed from the stacking direction, the conductor 14 is smaller than the power storage module 12, but may be the same as or larger than the power storage module 12. In other words, the conductor 14 is disposed in a region where the power storage module 12 is disposed when viewed from the stacking direction. The conductor 14 is electrically connected to the adjacent power storage module 12. Thereby, the some electrical storage module 12 is connected in series in the lamination direction.

  The conductors 14 are also arranged outside the power storage modules 12 positioned at both ends in the stacking direction of the power storage modules 12. That is, the conductors 14 are also arranged at both ends of the array body 11 in the stacking direction. In the stacking direction, a positive electrode terminal 24 is connected to the conductor 14 located at one end, and a negative electrode terminal 26 is connected to the conductor 14 located at the other end. The positive electrode terminal 24 and the negative electrode terminal 26 may be integrated with the conductor 14 to be connected. The positive electrode terminal 24 and the negative electrode terminal 26 extend in a direction (X direction) intersecting the stacking direction. The positive and negative terminals 24 and 26 can charge and discharge the power storage device 10.

  The power storage device 10 may include a restraining member 15 that restrains the alternately stacked power storage modules 12 and conductors 14 in the stacking direction. The restraining member 15 includes a pair of restraining plates 16 and 17 and a connecting member (bolt 18 and nut 20) for joining the restraining plates 16 and 17 together. For example, an insulating film 22 such as a resin film is disposed between the restraining plates 16 and 17 and the conductor 14. Each restraint plate 16 and 17 is comprised, for example with metals, such as iron.

  When viewed from the stacking direction, each of the restraining plates 16 and 17 and the insulating film 22 has, for example, a rectangular shape. The insulating film 22 is larger than the conductor 14, and the restraining plates 16 and 17 are larger than the power storage module 12. When viewed from the stacking direction, an insertion hole 16 a through which the shaft portion of the bolt 18 is inserted is provided at a position on the outer side of the power storage module 12 at the edge of the restraint plate 16. Similarly, when viewed from the stacking direction, an insertion hole 17 a through which the shaft portion of the bolt 18 is inserted is provided at the edge of the restraint plate 17 at a position outside the power storage module 12. When each restraint plate 16, 17 has a rectangular shape when viewed from the stacking direction, the insertion hole 16 a and the insertion hole 17 a are located at the corners of the restraint plates 16, 17.

  One constraining plate 16 is abutted against the conductor 14 connected to the negative electrode terminal 26 via the insulating film 22, and the other constraining plate 17 applies the insulating film 22 to the conductor 14 connected to the positive electrode terminal 24. Has been hit through. For example, the bolt 18 is passed through the insertion hole 16a and the insertion hole 17a from one restraint plate 16 side to the other restraint plate 17 side, and a nut 20 is provided at the tip of the bolt 18 protruding from the other restraint plate 17. Are screwed together. Accordingly, the insulating film 22, the conductor 14, and the power storage module 12 are sandwiched and unitized, and a restraining load is applied in the stacking direction.

  As shown in FIG. 2, the power storage module 12 includes a stacked body 30 in which a plurality of bipolar electrodes 32 are stacked in one direction (stacking direction). When viewed from the stacking direction of the bipolar electrode 32, the stacked body 30 has, for example, a rectangular shape. A separator 40 may be disposed between the adjacent bipolar electrodes 32. The bipolar electrode 32 includes an electrode plate 34, a positive electrode layer 36 provided on one surface of the electrode plate 34, and a negative electrode layer 38 provided on the other surface of the electrode plate 34. In the stacked body 30, the positive electrode layer 36 of one bipolar electrode 32 faces the negative electrode layer 38 of one bipolar electrode 32 adjacent in the stacking direction across the separator 40, and the negative electrode layer 38 of one bipolar electrode 32 is It faces the positive electrode layer 36 of the other bipolar electrode 32 adjacent in the stacking direction with the separator 40 interposed therebetween.

  In the stacking direction, an electrode plate 34 (negative electrode termination electrode) having a negative electrode layer 38 disposed on the inner surface is disposed at one end of the multilayer body 30, and a positive electrode layer 36 is disposed on the inner surface at the other end of the multilayer body 30. Is disposed on the electrode plate 34 (positive terminal electrode). The negative electrode layer 38 of the negative electrode side termination electrode is opposed to the positive electrode layer 36 of the uppermost bipolar electrode 32 with the separator 40 interposed therebetween. The positive electrode layer 36 of the positive electrode termination electrode faces the negative electrode layer 38 of the lowermost bipolar electrode 32 with the separator 40 interposed therebetween. The electrode plates 34 of these termination electrodes are connected to the adjacent conductors 14 (see FIG. 1).

  The power storage module 12 includes a frame body 50 that holds the edge portion 34 a of the electrode plate 34 on the side surface 30 a of the stacked body 30 that extends in the stacking direction of the bipolar electrodes 32. The frame body 50 is configured to surround the side surface 30 a of the stacked body 30. The frame 50 has, for example, a rectangular shape when viewed from the stacking direction of the bipolar electrodes 32. The frame 50 includes a first resin portion 52 that holds the edge portion 34a of the electrode plate 34, and a second resin portion 54 that is provided around the first resin portion 52 when viewed from the stacking direction.

  The first resin portion 52 constituting the inner wall of the frame 50 is provided from one surface (surface on which the positive electrode layer 36 is formed) of the electrode plate 34 of each bipolar electrode 32 to the end surface of the electrode plate 34 at the edge 34a. Yes. When viewed from the lamination direction of the bipolar electrodes 32, each first resin portion 52 is provided over the entire circumference of the edge portion 34 a of the electrode plate 34 of each bipolar electrode 32. Adjacent first resin portions 52 are welded to each other on the surface extending outside the other surface (surface on which the negative electrode layer 38 is formed) of the electrode plate 34 of each bipolar electrode 32. As a result, the edge portion 34 a of the electrode plate 34 of each bipolar electrode 32 is buried and held in the first resin portion 52. Similarly to the edge portion 34 a of the electrode plate 34 of each bipolar electrode 32, the edge portions 34 a of the electrode plates 34 disposed at both ends of the laminated body 30 are also held in a state of being buried in the first resin portion 52. Thus, an internal space V that is airtightly partitioned by the electrode plates 34 and 34 and the first resin portion 52 is formed between the electrode plates 34 and 34 adjacent in the stacking direction. In the internal space V, for example, an electrolytic solution (not shown) made of an alkaline solution such as an aqueous potassium hydroxide solution is accommodated.

  The second resin portion 54 constituting the outer wall of the frame body 50 is a cylindrical portion that extends over the entire length of the multilayer body 30 in the lamination direction of the bipolar electrode 32. The second resin portion 54 covers the outer surface of the first resin portion 52 extending in the stacking direction of the bipolar electrode 32. The second resin portion 54 is welded to the outer surface of the first resin portion 52 on the inner surface that extends in the stacking direction of the bipolar electrode 32.

  The electrode plate 34 is a rectangular metal foil made of nickel, for example. The edge 34 a of the electrode plate 34 is an uncoated region where the positive electrode active material and the negative electrode active material are not coated, and the uncoated region constitutes the first resin portion 52 constituting the inner wall of the frame 50. It is an area that is buried and held in the area. Examples of the positive electrode active material constituting the positive electrode layer 36 include nickel hydroxide. Examples of the negative electrode active material constituting the negative electrode layer 38 include a hydrogen storage alloy. The formation region of the negative electrode layer 38 on the other surface of the electrode plate 34 is slightly larger than the formation region of the positive electrode layer 36 on one surface of the electrode plate 34. The electrode plate 34 may be formed from a conductive resin.

  The separator 40 is formed in a sheet shape, for example. Examples of the material for forming the separator 40 include porous films made of polyolefin resins such as polyethylene (PE) and polypropylene (PP), woven fabrics and nonwoven fabrics made of polypropylene, polyethylene terephthalate (PET), methylcellulose and the like. It is. Moreover, the separator 40 may be reinforced with a vinylidene fluoride resin compound.

  The frame 50 (the first resin portion 52 and the second resin portion 54) is formed in a rectangular cylindrical shape by, for example, injection molding using an insulating resin. Examples of the resin material constituting the frame 50 include polypropylene (PP), polyphenylene sulfide (PPS), and modified polyphenylene ether (modified PPE).

  Next, the conductor 14 will be described in detail with reference to FIGS. 1, 3, and 4. As shown in FIGS. 1, 3, and 4, the conductor 14 is disposed between the power storage modules 12 and 12 adjacent to each other, or between the power storage module 12 and the insulating film 22. That is, the conductor 14 is laminated in one direction with respect to the power storage module 12. The conductors 14 disposed between the adjacent power storage modules 12 and 12 are in contact with the respective power storage modules 12 at both end surfaces in the stacking direction. The conductor 14 disposed between the power storage module 12 and the insulating film 22 is in contact with the power storage module 12 at one end face in the stacking direction.

  The conductor 14 also functions as a heat radiating plate for releasing heat generated in the power storage module 12. Specifically, the conductor 14 has higher thermal conductivity than the contact surface 12 a of the power storage module 12 that contacts the conductor 14. The conductor 14 has a first region R1 located on one side in the intersecting direction (Y direction) intersecting the stacking direction, and a second region R2 located on the other side in the intersecting direction. In addition, a plurality of through holes 14 a extending in the intersecting direction (Y direction) are provided inside the conductor 14. The through hole 14a communicates from one end surface facing each other in the intersecting direction to the other end surface. The through holes 14a are arranged in a direction (X direction) intersecting the stacking direction and the intersecting direction. A coolant F such as air flows through the through hole 14a from the first region R1 side toward the second region R2 side. Thus, by circulating the refrigerant F through the through hole 14a, the heat generated in the power storage module 12 can be effectively released to the outside. The power storage device 10 may be provided with a device that actively circulates (circulates) air through the through hole 14a.

  The dimensions of the conductor 14, the material of the conductor 14, the dimensions of the through holes 14a, the number of the through holes 14a, and the like can be adjusted as appropriate so that the temperature of the power storage device 10 does not exceed 50 ° C, for example. Examples of the material of the conductor 14 include aluminum. In the present embodiment, the through hole 14a viewed from the crossing direction has a rectangular shape. In addition, the shape of the through-hole 14a seen from the crossing direction is not limited to a rectangular shape, For example, a circular shape etc. can be changed suitably.

  The dimension L of the first region R1 in the intersecting direction can be, for example, about 5% to 50% of the dimension of the conductor 14 in the intersecting direction. In the present embodiment, the dimension L of the first region R1 in the intersecting direction is 50% of the dimension of the conductor 14 in the intersecting direction. In the direction crossing the stacking direction and the crossing direction (X direction), the first region R1 is provided over the entire conductor 14. The second region R2 is a region other than the first region R1 in the conductor 14.

  The first region R1 is provided with a heat exchange suppression unit 19 that suppresses heat exchange between the conductor 14 and the refrigerant flowing in the through hole 14a. The heat exchange suppression unit 19 is made of a material having lower thermal conductivity than the conductor 14. Thereby, the heat conductivity in 1st area | region R1 is lower than the heat conductivity in 2nd area | region R2. As shown in FIG. 4, the heat exchange suppressing portion 19 is formed on the entire inner wall of the through hole 14a along the inner wall of the through hole 14a in the first region R1. In the crossing direction, the heat exchange suppression unit 19 is formed over the entire first region R1. The thickness T of the heat exchange suppression unit 19 can be set to, for example, 0.05 mm to 1 mm. The thickness T of the heat exchange suppressing part 19 in the first region R1 is substantially uniform. In addition, the thickness T of the heat exchange suppression part 19 is not specifically limited, It can change suitably in the range in which sufficient quantity of the refrigerant | coolant F can distribute | circulate through the through-hole 14a. As a material constituting the heat exchange suppression unit 19, for example, a resin such as polypropylene (PP), epoxy, polytetrafluoroethylene (PTFE), paint, or the like can be used.

  Here, a method of forming the heat exchange suppression unit 19 in the first region R1 of the conductor 14 will be described. First, the conductor 14 having the through hole 14a is prepared. The conductor 14 can be manufactured by a known method such as extrusion. Next, the resin material that becomes the heat exchange suppression unit 19 is melted in a liquid state, and the first region R1 of the conductor 14 is immersed in the liquid resin material. At this time, the conductor 14 is immersed in the resin material in a state where the outer peripheral surface of the conductor 14 is protected by masking or the like. Thereafter, the liquid resin material is cured by heating or the like to remove the masking. Thereby, the heat exchange suppression part 19 along the inner wall of the through-hole 14a is formed in 1st area | region R1.

  As described above, in power storage device 10, heat conductivity in first region R <b> 1 of conductor 14 is lower than heat conductivity in second region R <b> 2 of conductor 14. In a general power storage device, since the entire conductor has substantially the same heat transfer property, the temperature of the refrigerant rises due to heat exchange between the conductor and the refrigerant on the upstream side, and sufficient cooling capacity is also provided on the downstream side. It is difficult to circulate the refrigerant in a state where it is maintained. Therefore, the downstream area is less likely to be cooled than the upstream area, and as shown in FIG. 5, a temperature difference occurs between the upstream area and the downstream area. As a result, variations in resistance values due to temperature differences occur and current tends to flow only in part of the bipolar electrode, so that the bipolar electrode is likely to deteriorate.

  On the other hand, in the power storage device 10, when the refrigerant F is circulated in the through hole 14a, the heat exchange between the conductor 14 and the refrigerant F in the first region R1 is performed in the second region R2. It is suppressed compared with heat exchange. Therefore, by causing the refrigerant F to flow from the first region R1 side toward the second region R2 side, the temperature rise of the refrigerant F in the first region R1 is suppressed, and sufficient cooling capacity is also provided to the second region R2. The maintained refrigerant F can be circulated. As a result, variation in the cooling capacity between the first region R1 and the second region R2 is suppressed, so that the temperature of the bipolar electrode 32 can be made uniform.

  The first region R1 is provided with a heat exchange suppression unit 19 that suppresses heat exchange between the conductor 14 and the refrigerant F. Thereby, the heat conductivity in 1st area | region R1 can be adjusted by adjusting the material, shape, etc. of the heat exchange suppression part 19. FIG.

  Moreover, the heat exchange suppression part 19 is formed along the inner wall of the through-hole 14a. Thereby, while ensuring the conductivity between the conductor 14 and the power storage module 12, heat exchange between the conductor 14 and the refrigerant F in the first region R1 is suppressed, and the temperature of the bipolar electrode 32 is made uniform. be able to.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to said embodiment, A various change can be made. For example, in the above embodiment, the example in which the thickness T of the heat exchange suppression unit 19 is substantially uniform has been described. However, the thickness T of the heat exchange suppression unit 19 may not be uniform. For example, the thickness T of the heat exchange suppression unit 19 may be gradually reduced from the first region R1 side toward the second region R2 side. Moreover, the thickness T of the heat exchange suppression unit 19 may be gradually reduced from the first region R1 side toward the second region R2 side.

  In the above-described embodiment, the example in which the heat exchange suppression unit 19 is formed along the inner wall of the through hole 14a has been described. However, when the heat exchange suppression unit 19 is made of a conductive material, You may form the heat exchange suppression part 19 in the both end surfaces of the conductor 14 in the lamination direction.

  Further, in the above embodiment, the example in which the heat transfer suppression unit 19 reduces the heat transfer property in the first region R1 has been described. However, the heat treatment or shot blasting is performed on the conductor 14 without using the heat exchange suppression unit 19. The heat transfer in the first region R1 may be reduced by performing processing or the like.

  In the above embodiment, the example in which the heat transfer in the first region R1 is reduced has been described. However, by improving the heat transfer in the second region R2, the heat transfer in the first region R1 is improved in the second region R2. It is good also as a state lower than heat conductivity. For example, by providing fine irregularities on the inner wall surface of the through hole 14a in the second region R2 (by roughening the inner wall surface of the through hole 14a), the contact area between the conductor 14 and the refrigerant F is increased. The heat transfer property in the second region R2 can be improved.

  In the above-described embodiment, the example in which air is circulated as the refrigerant F through the through hole 14a of the conductor 14 has been described. However, liquid refrigerant F may be circulated instead of air. Examples of the liquid refrigerant F include insulating oil. In this case, the heat dissipation in the conductor 14 can be further improved. The liquid refrigerant F is an insulating material. Thereby, even if it is a case where the refrigerant | coolant F leaks from the through-hole 14a, the short circuit by the refrigerant | coolant F can be prevented, for example.

Moreover, although said electrical storage apparatus 10 demonstrated the example which is a nickel hydride secondary battery in said embodiment, the electrical storage apparatus 10 may be a lithium ion secondary battery. In this case, the positive electrode active material is, for example, a composite oxide, metallic lithium, sulfur or the like. Examples of the negative electrode active material include graphite, highly oriented graphite, carbon such as mesocarbon microbeads, hard carbon, and soft carbon, alkali metals such as lithium and sodium, metal compounds, SiO _x (0.5 ≦ x ≦ 1.5 ) And the like, and boron-added carbon.

  DESCRIPTION OF SYMBOLS 10 ... Power storage device, 12 ... Power storage module, 14 ... Conductor, 14a ... Through-hole, 19 ... Heat exchange suppression part, 30 ... Laminated body, 32 ... Bipolar electrode, 34 ... Electrode plate, 36 ... Positive electrode layer, 38 ... Negative electrode Layer, 40 ... Separator, F ... Refrigerant, R1 ... First region, R2 ... Second region.

Claims (3)

A power storage device comprising a power storage module in which a plurality of bipolar electrodes each having a positive electrode layer provided on one surface of an electrode plate and a negative electrode layer provided on the other surface of the electrode plate are stacked in one direction with a separator interposed therebetween. And
A conductor disposed in a state of being stacked in the one direction with respect to the power storage module and in contact with the power storage module,
The conductor has a first region located on one side of the intersecting direction intersecting the one direction, and a second region located on the other side of the intersecting direction,
The conductor is provided with a through-hole extending in the intersecting direction and through which the refrigerant flows from the first region side toward the second region side,
The power storage device in which heat conductivity in the first region is lower than heat conductivity in the second region.   The power storage device according to claim 1, wherein a heat exchange suppression unit that suppresses heat exchange between the conductor and the refrigerant is provided in the first region.   The power storage device according to claim 2, wherein the heat exchange suppression unit is formed along an inner wall of the through hole.