JP2019125564A - Power storage module - Google Patents

Abstract

To provide a power storage module capable of restraining occurrence of problems due to concentration of load on a part of a collector held by a frame body.SOLUTION: A power storage module includes multiple bipolar electrodes. Each of the multiple bipolar electrodes includes a collector having a plate shape extending in a direction intersecting the lamination direction, and having an outer peripheral edge part covered and held by a frame body placed around the bipolar electrode in the intersection direction, and a positive electrode layer provided on the first face of the collector, and located farther inside than the outer peripheral edge part in the intersection direction, and a negative electrode layer provided on the second face of the collector, and located farther inside than the outer peripheral edge part in the intersection direction. The collector is provided with the outer peripheral edge part, and an exposure part located between a region of the first face where the positive electrode layer is provided and a region of the second face where the negative electrode layer is provided, the exposure part is located between the frame body and the negative electrode layer in the intersection direction, and has a long portion longer than the interval of the frame body and the negative electrode layer in the intersection direction.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a storage module.

  As a power storage device, a power storage module having a stacked body in which bipolar electrodes are stacked is known. In Patent Document 1 below, a laminate is formed by laminating a bipolar electrode including a current collector, a positive electrode layer provided on one surface of the current collector, and a negative electrode layer provided on the other surface of the current collector. A storage module having a body is disclosed.

JP, 2008-78109, A

  The current collector of the bipolar electrode as described above may be deformed due to an external force applied at the time of manufacture of the power storage module, and internal pressure fluctuation at the time of charge and discharge of the power storage module. In order to suppress the deformation of the current collector, for example, the edge of the current collector of each bipolar electrode may be held by a frame.

  However, when the current collector is held by the frame, any of the positive electrode layer and the negative electrode layer is provided in the current collector due to the external force and the internal pressure fluctuation, and either the positive electrode layer or the negative electrode layer. Also, the load (stress) tends to be concentrated at the boundary with the portion not provided.

  Further, due to the external force and the internal pressure fluctuation, the load tends to be concentrated on the boundary between the edge portion held by the frame in the current collector and the portion not held by the frame. The concentration of the load may cause breakage or the like of the current collector and / or the frame, which may cause problems such as an increase in electric resistance, a short circuit in the battery, and a leak of the electrolyte.

  An object of one aspect of the present invention is to provide a power storage module capable of suppressing occurrence of a failure due to concentration of load on a part of a current collector held by a frame.

  An electricity storage module according to one aspect of the present invention is an electricity storage module including a plurality of bipolar electrodes, and each of the plurality of bipolar electrodes has a plate shape extending in a crossing direction intersecting the stacking direction of the plurality of bipolar electrodes. A current collector having a pair of plate surfaces extending in the cross direction and an outer peripheral edge covered and held by a frame disposed around the bipolar electrode in the cross direction; A positive electrode layer provided on the first surface which is one of the plate surfaces, which is located inside the outer peripheral edge in the cross direction, and the other of the pair of plate surfaces of the current collector And a negative electrode layer provided on a second surface and positioned inside the outer peripheral edge in the cross direction, and the current collector includes the outer peripheral edge in the cross direction and the positive electrode of the first surface The area where the layer is provided and the area where the negative electrode layer of the second surface is provided And the exposed portion is located between the frame and the negative electrode layer in the cross direction and has an elongated portion longer than the distance between the frame and the negative electrode layer in the cross direction. .

  According to this storage module, the exposed portion of the current collector is positioned between the frame and the negative electrode layer in the cross direction, and has an elongated portion longer than the distance between the frame and the negative electrode layer along the cross direction. . For this reason, when pressure is applied to the current collector at the time of charge and discharge of the storage module, bending is easily generated in the long portion. Thus, for example, in the current collector, a region on the first surface where the positive electrode layer is provided and a region on the second surface where the negative electrode layer is provided, the boundary between the exposed portion of the current collector, and the frame in the current collector The load concentrated on the boundary between the outer peripheral edge covered and held and the exposed portion of the current collector is well dispersed by the elongated portion. Therefore, it is possible to suppress the occurrence of a failure due to the concentration of the load on a part of the current collector held by the frame.

  The long portion may be provided with a curved portion exhibiting a curved shape that protrudes along the stacking direction. In this case, when pressure is applied to the current collector at the time of charge and discharge of the storage module, the curved portion of the long portion is easily compressed in the cross direction, thereby applying a load on the current collector. Can be well dispersed.

  The maximum protrusion amount of the curved portion may be smaller than the distance between the adjacent current collectors in the stacking direction. In this case, it is possible to prevent the curved portion from being in contact with the adjacent current collector and causing a short circuit.

  The storage module further includes a separator provided between adjacent bipolar electrodes along the stacking direction, and in the cross direction, the outer peripheral edge of the separator is positioned between the maximum projecting point of the curved portion and the frame You may In this case, the separator is positioned between the adjacent current collector and the curved portion in the stacking direction. Therefore, a short circuit between the current collectors is well prevented by the separator.

  The curved portion may have a curved shape that protrudes from the negative electrode layer toward the positive electrode layer. In a bipolar electrode, the negative electrode layer tends to expand more easily than the positive electrode layer. For this reason, since a load is easily applied to the current collector from the negative electrode layer side, the load can be efficiently dispersed by the curved portion having a curved shape protruding toward the positive electrode layer side.

  The bending portion has a first bending portion and a second bending portion positioned outside the first bending portion in the intersecting direction, and the protruding direction of the first bending portion and the protruding direction of the second bending portion And may be different from each other. In this case, since the load applied to each bending portion can be reduced, breakage of the bending portion can be suppressed.

  The curved portion may have a wavy shape when viewed from the stacking direction. In this case, concentration of load on a part of the bending portion can be suppressed.

  The current collector may have a rectangular shape as viewed in the stacking direction, and the long portion may be provided on the current collector along the four sides of the current collector as viewed in the stacking direction. In this case, the load can be distributed over the entire long portion.

  ADVANTAGE OF THE INVENTION According to this invention, the electrical storage module which can suppress generation | occurrence | production of the malfunction by concentration of the load to a part of current collector hold | maintained by a frame can be provided.

FIG. 1 is a schematic cross-sectional view showing a power storage device provided with a power storage module according to the embodiment. FIG. 2 is a schematic cross-sectional view showing an electricity storage module constituting the electricity storage device of FIG. 3 (a) is a schematic plan view of the storage module, and FIG. 3 (b) is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. 3 (a). FIG. 4 is an enlarged sectional view of an essential part of the storage module. FIGS. 5 (a) and 5 (b) are enlarged cross-sectional views of relevant parts of a battery module according to a comparative example. FIG. 6A is an enlarged sectional view of an essential part showing a storage module of a first modification of the embodiment, and FIG. 6B is an enlarged cross section of the storage module of a second modification of the embodiment It is a figure, and Drawing 6 (c) is an important section expanded sectional view showing an electricity storage module of the 3rd modification of an embodiment. FIG. 7 is a schematic plan view showing a storage module of a fourth modification of the embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. In the description of the drawings, the same or equivalent elements will be denoted by the same reference symbols, without redundant description. The dimensional ratios in the drawings do not necessarily match those in the description.

  An embodiment of a power storage device will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing a power storage device provided with a power storage module according to the embodiment. Power storage device 10 shown in FIG. 1 is used, for example, as a battery of various vehicles such as a forklift, a hybrid car, and an electric car. The storage device 10 includes a plurality of (three in the present embodiment) storage modules 12, but may include a single storage module 12. The storage module 12 is a bipolar battery. The storage module 12 is a secondary battery such as, for example, a nickel hydrogen secondary battery or a lithium ion secondary battery. The secondary battery may be an all solid state battery. The storage module 12 may be an electric double layer capacitor. The following description exemplifies a nickel-hydrogen secondary battery.

  The plurality of storage modules 12 are stacked via a conductive plate 14 such as a metal plate, for example. As viewed from the stacking direction (Z direction) of the plurality of storage modules 12, the storage module 12 and the conductive plate 14 have, for example, a rectangular shape. Details of each storage module 12 will be described later. The conductive plates 14 are also disposed outside the storage modules 12 positioned at both ends in the stacking direction of the plurality of storage modules 12. Conductive plate 14 is electrically connected to adjacent power storage module 12. Thereby, the plurality of power storage modules 12 are connected in series in the stacking direction. In the stacking direction, the positive electrode terminal 24 is connected to the conductive plate 14 located at one end, and the negative electrode terminal 26 is connected to the conductive plate 14 located at the other end. The positive electrode terminal 24 may be integral with the conductive plate 14 to be connected. The negative electrode terminal 26 may be integral with the conductive plate 14 to be connected. The positive electrode terminal 24 and the negative electrode terminal 26 extend in a direction intersecting with the stacking direction of the plurality of storage modules 12 (in the present embodiment, the X direction shown in FIG. 1). The charge and discharge of the power storage device 10 can be performed by the positive electrode terminal 24 and the negative electrode terminal 26. Hereinafter, the direction in which the storage modules are stacked is simply referred to as the “stacking direction”. In the present embodiment, “viewing in the stacking direction” corresponds to planar view.

  Conductive plate 14 can also function as a heat sink for releasing the heat generated in storage module 12. By passing a refrigerant such as air or gas through the plurality of air gaps 14 a provided inside the conductive plate 14, the heat from the storage module 12 can be efficiently released to the outside. Each void 14a extends, for example, in a direction intersecting the stacking direction (in the present embodiment, in the Y direction shown in FIG. 1). When viewed in the stacking direction, conductive plate 14 is smaller than storage module 12, but may be the same as or larger than storage module 12.

  The storage device 10 may include a restraint member 16 for restraining the storage modules 12 and the conductive plates 14 stacked alternately in the stacking direction. The constraining member 16 includes a pair of constraining plates 16A and 16B and a connecting member (bolt 18 and nut 20) that interconnects the constraining plates 16A and 16B. An insulating film 22 such as a resin film, for example, is disposed between the restraint plates 16A and 16B and the conductive plate 14. Each restraint plate 16A, 16B is made of, for example, a metal such as iron. When viewed from the stacking direction, each of the restraint plates 16A, 16B and the insulating film 22 has, for example, a rectangular shape. The insulating film 22 is larger than the conductive plate 14, and the restraint plates 16 </ b> A and 16 </ b> B are larger than the storage module 12. As viewed in the stacking direction, an insertion hole 16A1 for inserting the shaft of the bolt 18 is provided at a position outside the storage module 12 at the edge of the restraint plate 16A. Similarly, as viewed in the stacking direction, an insertion hole 16B1 for inserting the shaft of the bolt 18 is provided at a position outside the storage module 12 at the edge of the restraint plate 16B. When the restraint plates 16A and 16B have a rectangular shape when viewed from the stacking direction, the insertion holes 16A1 and the insertion holes 16B1 are located at the corners of the restraint plates 16A and 16B.

  One restraint plate 16A is abutted against the conductive plate 14 connected to the negative electrode terminal 26 via the insulating film 22, and the other restraint plate 16B is attached to the conductive plate 14 connected to the positive electrode terminal 24. It is hit through. The bolt 18 is passed through the insertion hole 16A1 and the insertion hole 16B1 from, for example, one restraint plate 16A to the other restraint plate 16B. A nut 20 is screwed into the tip of a bolt 18 projecting from the other restraint plate 16B. Thus, the insulating film 22, the conductive plate 14, and the storage module 12 are sandwiched to form a unit, and a restraint load is applied in the stacking direction.

  With reference to FIG. 2, a power storage module constituting the power storage device will be described. FIG. 2 is a schematic cross-sectional view showing an electricity storage module constituting the electricity storage device of FIG. The storage module 12 shown in FIG. 2 includes a stack 30 including a plurality of bipolar electrodes 32 stacked along the stacking direction. As viewed from the stacking direction, the stacked body 30 has, for example, a rectangular shape. A separator 40 can be disposed between the adjacent bipolar electrodes 32 along the stacking direction. That is, the stacked body 30 has a plurality of bipolar electrodes 32 and a plurality of separators 40.

  The storage module 12 includes a cylindrical resin portion 50 that extends in the stacking direction and accommodates the stacked body 30. The resin portion 50 is a member configured to surround the stacked body 30. The resin portion 50 has, for example, a rectangular frame shape when viewed from the stacking direction of the bipolar electrode 32. That is, the resin portion 50 has, for example, a rectangular cylindrical shape. As a resin material which constitutes resin part 50, polypropylene (PP), polyphenylene sulfide (PPS), or modified polyphenylene ether (modified PPE) etc. are mentioned, for example. The resin portion 50 is formed by, for example, injection molding.

  The resin portion 50 has a plurality of first seal portions 52 held in contact with the stacked body 30 and a crossing direction crossing in the stacking direction (X direction and Y direction, hereinafter referred to as “horizontal direction”) And a second seal portion 54 provided outside the first seal portion 52. The second seal portion 54 is provided in a state of being sealed with the first seal portion 52. That is, when viewed from the stacking direction, the first seal portion 52 is provided around the stack 30 to hold the plurality of bipolar electrodes 32, and the cylindrical second seal portion 54 is around the first seal portion 52. Provided in

  The first seal portion 52 constituting the inner wall of the resin portion 50 is provided to hold the corresponding bipolar electrode 32, and a frame covering the entire periphery of the corresponding bipolar electrode 32 (that is, the stacked body 30) It is a body. The first seal portion 52 is disposed around the corresponding bipolar electrode 32 in the horizontal direction. In the stacking direction, the thickness of the first seal portion 52 is larger than the sum of the thickness of the bipolar electrode 32 and the thickness of the separator 40. The first seal portion 52 is formed, for example, by liquid- and gas-tight welding to the bipolar electrode 32. Moreover, 1st seal | sticker part 52 comrades adjacent in a lamination direction are liquid-tightly and airtightly welded. Thus, an internal space partitioned in a fluid-tight and air-tight manner by the bipolar electrodes 32, 32 and the first seal portion 52 is formed between the bipolar electrodes 32 adjacent in the stacking direction. In the internal space, an electrolytic solution (not shown) made of an alkaline solution such as, for example, an aqueous solution of potassium hydroxide, an aqueous solution of lithium hydroxide, or a mixture thereof is accommodated. In addition, when calling it the "volume of internal space", the volume containing the space | gap of the separator 40 is meant.

  The second seal portion 54 constituting the outer wall of the resin portion 50 covers the outer peripheral surface 52 a of the first seal portion 52 extending in the stacking direction. The inner peripheral surface of the second seal portion 54 is welded, for example, to the outer peripheral surface 52a of the first seal portion 52, and seals the outer peripheral surface 52a. That is, the second seal portion 54 is joined to the outer peripheral surface 52 a of the first seal portion 52. The welding surface (joining surface) of the second seal portion 54 with respect to the first seal portion 52 exhibits, for example, four rectangular planes.

  Next, the bipolar electrode 32 will be described in detail with reference to FIGS. 3 (a) and 3 (b) and FIG. 4 in addition to FIG. 3 (a) is a schematic plan view of the storage module, and FIG. 3 (b) is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. 3 (a). FIG. 4 is an enlarged sectional view of an essential part of the storage module. As shown in FIGS. 2 and 4, each of the plurality of bipolar electrodes 32 includes a current collector 34, a positive electrode layer 36, and a negative electrode layer 38. The current collector 34 has a pair of plate surfaces intersecting in the stacking direction. The positive electrode layer 36 is provided on the first surface 34 a that is one of the pair of plate surfaces of the current collector 34, and the second plate surface that is the other of the pair of plate surfaces of the current collector 34. The negative electrode layer 38 is provided on the surface 34 b. Therefore, the current collector 34 is sandwiched between the positive electrode layer 36 and the negative electrode layer 38 along the stacking direction.

  The current collector 34 is a flexible conductor exhibiting a horizontally extending plate shape intersecting the stacking direction. The current collector 34 is, for example, a nickel foil, a plated steel plate, or a plated stainless steel plate. As a steel plate, the cold-rolled steel plate (SPCC etc.) prescribed | regulated, for example by JISG 3141: 2005 is mentioned. As a stainless steel plate, SUS304 etc. which are prescribed by JIS G 4305: 2015 are mentioned, for example. The thickness of the current collector 34 is, for example, 0.1 μm or more and 1000 μm or less. As a positive electrode active material which comprises the positive electrode layer 36, nickel hydroxide is mentioned, for example. As a negative electrode active material which comprises the negative electrode layer 38, a hydrogen storage alloy is mentioned, for example. Immediately after the bipolar electrode 32 is manufactured, the region of the positive electrode layer 36 on the first surface 34 a of the current collector 34 may be larger than the region of the negative electrode layer 38 on the second surface 34 b of the current collector 34.

  As shown in FIGS. 3A and 4, the peripheral portion 34 c of the current collector 34 is an uncoated region where the positive electrode layer 36 and the negative electrode layer 38 are not provided. In other words, each of the positive electrode layer 36 and the negative electrode layer 38 is provided so as to be located inside the peripheral portion 34 c of the current collector 34 in the horizontal direction. The outer peripheral edge 61 located on the edge side of the peripheral edge 34 c is covered by the first seal portion 52 of the resin portion 50. Therefore, the outer peripheral edge portion 61 of the current collector 34 is held in a state of being buried in the first seal portion 52. Further, the peripheral portion 34 c is located between the region where the positive electrode layer 36 of the first surface 34 a is provided and the region where the negative electrode layer 38 of the second surface 34 b is provided and the outer peripheral edge 61 in the horizontal direction. An exposed portion 62 is provided. The region of the first surface 34 a where the positive electrode layer 36 is provided corresponds to the region in contact with the positive electrode layer 36 on the first surface 34 a. Similarly, a region of the second surface 34 b where the negative electrode layer 38 is provided corresponds to a region in contact with the negative electrode layer 38 on the second surface 34 b. Along the horizontal direction, the exposed portion 62 may be located between the outer edge portion 61 and a region overlapping the current collector 34 in the stacking direction with respect to both the positive electrode layer 36 and the negative electrode layer 38. . That is, the exposed portion 62 may be located between the coated region of the current collector 34 and the outer peripheral edge portion 61 along the horizontal direction.

  The exposed portion 62 is a portion of the current collector 34 that is exposed from any of the first seal portion 52, the positive electrode layer 36, and the negative electrode layer 38. The exposed portion 62 is located between the first seal portion 52 and the negative electrode layer 38 in the horizontal direction, and has an elongated portion 71 longer than the interval S1 between the first seal portion 52 and the negative electrode layer 38 along the horizontal direction. . Therefore, the length of the elongated portion 71 is larger than the interval S1 along the horizontal direction between the first seal portion 52 and the negative electrode layer 38. In the present embodiment, the distance S1 is a distance along the X direction between the end surface 38a of the negative electrode layer 38 immediately after the manufacture of the storage module 12 and the inner peripheral surface 52b of the first seal portion 52 (see FIG. 4) .

  The long portion 71 is provided with a curved portion 71 a having a curved shape that protrudes along the stacking direction. As shown in FIG. 3A, the curved portion 71a is configured as a groove having a frame shape provided on the current collector 34 so as to surround the negative electrode layer 38 when viewed in the stacking direction. For this reason, the long portions 71 are provided on the current collector 34 along the four sides of the current collector 34 when viewed in the stacking direction, and are provided over the entire exposed portion 62. Therefore, in the present embodiment, the exposed portion 62 and the long portion 71 are substantially the same. In the present embodiment, the curved portion 71a is provided so as to have a square frame shape with rounded corners when viewed in the stacking direction. In addition, as shown in FIG. 3 (b), the curved portion 71a is formed to have a wavy shape when viewed from the stacking direction.

  The curved portion 71 a is, for example, a processed portion formed by performing pressing or the like on a part of the exposed portion 62. In the present embodiment, the curved portion 71 a is curved in a bow shape as viewed from the horizontal direction, and has a substantially arc shape. As described above, since the current collector 34 exhibits flexibility, the curved portion 71 a is configured to be horizontally compressible. For example, when the current collector 34 stretches in accordance with the load from the negative electrode layer 38 or the like, the curved portion 71 a is compressed.

  The curved portion 71 a is curved so as to protrude from the negative electrode layer 38 toward the positive electrode layer 36. This is because the negative electrode layer 38 tends to expand more easily than the positive electrode layer 36 due to charge and discharge of the storage module 12 or the like. Therefore, the pressure applied to the current collector 34 by the expansion of the negative electrode layer 38 can be suitably dispersed by the compression of the curved portion 71 a by the curved portion 71 a having a curved shape projecting toward the positive electrode layer 36 side. . For example, after the storage module performs a large number of charge and discharge reactions, the expansion coefficient of the volume of the negative electrode active material (for example, hydrogen storage alloy) is more than the expansion coefficient of the volume of the positive electrode active material (for example, nickel hydroxide) It may be doubled. The expansion of the negative electrode layer 38 occurs, for example, when the hydrogen storage alloy absorbs hydrogen when the power storage device is charged, and the hydrogen storage alloy is pulverized as the charge and discharge reaction is repeated. In the pulverization of a hydrogen storage alloy, when the hydrogen storage alloy repeats the storage and release of hydrogen, stress caused by the movement of hydrogen is repeatedly applied to the inside of the particles of the hydrogen storage alloy. As a result, dislocations are accumulated in crystal grain boundaries and crystal subgrain boundaries inside the grains to generate and grow vacancies, which are caused by the development of cracks in the alloy.

  The maximum protrusion amount E1 of the curved portion 71a in the stacking direction is smaller than the distance between the adjacent current collectors 34 along the stacking direction. In this case, a short circuit between adjacent current collectors 34 can be prevented. In the present embodiment, the maximum protrusion amount E1 is smaller than the thickness of the positive electrode layer 36. Specifically, the maximum protrusion amount E1 may be thinner than the thickness of the bipolar electrode 32. Since the separators 40 exist between the adjacent bipolar electrodes 32, contact with the adjacent current collectors 21 is inhibited by the separators 40, and a short circuit between the current collectors 21 does not occur. The maximum protrusion amount E1 is preferably, for example, 0.3 times or more and less than 1 time of the thickness of the positive electrode layer 36. When the maximum protrusion amount E1 is 0.3 times or more, the curved portion 71a is well compressed along the horizontal direction, and the pressure is dispersed. When the maximum protrusion amount E1 is less than 1 time, the separator 40 is compressed and bent to cause positional deviation of the separator 40, thereby suppressing occurrence of a short circuit. The maximum protrusion amount E1 corresponds to the distance along the stacking direction from the maximum protrusion point P that protrudes most in the curved portion 71a to the first surface 34a of the current collector 34. The maximum protrusion amount E1 of the curved portion 71a may not necessarily be constant. For example, the maximum amount of protrusion of some curved portions 71a may be larger or smaller than the maximum amount of protrusion of other portions.

  In the horizontal direction, the outer peripheral edge 40 a of the separator 40 is located between the maximum projecting point P of the curved portion 71 a and the first seal portion 52. In other words, the outer peripheral edge 40a of the separator 40 in the horizontal direction is located closer to the first seal portion 52 than the maximum projecting point P of the curved portion 71a. In this case, the separator 40 can prevent contact between the current collector 34 adjacent to the positive electrode layer 36 in the stacking direction and the maximum protruding point P. In the present embodiment, the outer peripheral edge 40 a of the separator 40 is separated from the first seal portion 52, but the outer peripheral edge 40 a may be in contact with the first seal portion 52. In this case, even when the curved portion 71a is compressed and the maximum protruding point P is moved from the position before the compression of the curved portion 71a, the separator 40 can prevent a short circuit between the current collectors 34. The separator 40 is, for example, a sheet-like insulating member having a rectangular shape. Examples of the material for forming the separator 40 include porous films made of polyolefin resins such as polyethylene (PE) and polypropylene (PP), and woven or non-woven fabrics made of polypropylene and the like. The separator 40 may be reinforced with a vinylidene fluoride resin compound or the like.

  In the stacking direction, the current collector 34 in which the positive electrode layer 36 is disposed on the inner side surface (lower surface in the drawing) is disposed at one end (upper side in the drawing) of the laminate 30. The current collector 34 corresponds to a terminal electrode on the positive electrode side. In the stacking direction, at the other end (the lower side in the drawing) of the stacked body 30, the current collector 34 in which the negative electrode layer 38 is disposed on the inner side surface (the upper surface in the drawing) is disposed. The current collector 34 corresponds to the terminal electrode on the negative electrode side. The current collectors 34 of these terminal electrodes are connected to the adjacent conductive plates 14 (see FIG. 1). The stacked body 30 according to the present embodiment is configured by a plurality of stacked bipolar electrodes 32 and each terminal electrode in the stacking direction. The outer peripheral edge portion of the current collector 34 of each terminal electrode disposed at both ends of the laminated body 30 is also held in a state of being buried in the first seal portion 52.

  Below, the effect of the battery module which concerns on this embodiment is demonstrated, referring the comparative example shown by FIG. 5 (a), (b). FIGS. 5 (a) and 5 (b) are enlarged cross-sectional views of relevant parts of a battery module according to a comparative example. FIG. 5A shows a state before the negative electrode layer 38 expands, and FIG. 5B shows a state after the negative electrode layer 38 expands. As shown in FIGS. 5A and 5B, the exposed portion 62 of the bipolar electrode 132 in the comparative example is provided with the elongated portion 71 (more specifically, the curved portion 71a) of the present embodiment. Not.

  As described above, when the bipolar electrode 132 is repeatedly charged and discharged, the negative electrode layer 38 tends to expand as shown in FIG. 5 (b). Here, since the outer peripheral edge portion 61 of the current collector 134 of the bipolar electrode 132 is constrained by the first seal portion 52, the current collector 134 is prevented from extending in response to the expansion of the negative electrode layer 38. There is. For this reason, a load generated due to the expansion of the negative electrode layer 38 is applied to the current collector 134. Due to the configuration of the bipolar electrode 132, this load tends to concentrate on the boundary B1 between the expanded negative electrode layer 38 and the exposed portion 62 and the boundary B2 between the first seal portion 52 and the exposed portion 62. Such concentration of load is likely to occur because the current collector 134 is constrained by the first seal portion 52. Therefore, in the bipolar electrode 132 according to the comparative example, breakage of the current collector 134 at the boundary B1 and / or cracking or breakage of the resin portion 50 (particularly, the first seal portion 52) at the boundary B2 is likely to occur. If such breakage or the like occurs, not only increase in the electrical resistance of the bipolar electrode 132 but also problems such as short circuit in the storage module 12 and leakage of the electrolyte may occur.

  On the other hand, according to the storage module 12 of the present embodiment, the exposed portion 62 of the current collector 34 is located between the first seal portion 52 and the negative electrode layer 38 in the horizontal direction, and extends in the horizontal direction. An elongated portion 71 longer than a space S1 between the first seal portion 52 and the negative electrode layer 38 is provided. Further, the long portion 71 is provided with a curved portion 71 a having a curved shape that protrudes along the stacking direction. Therefore, when pressure is applied to the current collector 34 at the time of charge and discharge of the storage module 12, the curved portion 71a of the elongated portion 71 is easily compressed along the horizontal direction. Thus, for example, in the current collector 34, the boundary B1 between the region of the first surface 34a where the positive electrode layer 36 is provided and the region of the second surface 34b where the negative electrode layer 38 is provided, and the exposed portion 62 of the current collector 34; The load which tends to be concentrated on the boundary B1 between the outer peripheral edge portion 61 covered and held by the first seal portion 52 in the current collector 34 and the exposed portion 62 of the current collector 34 is good by the curved portion 71a. Distributed to Therefore, in the present embodiment, it is possible to suppress the occurrence of a defect due to the load being concentrated on a part of the current collector 34 held by the first seal portion 52.

  In addition, when the resin portion 50 is formed by injection molding, for example, an injection pressure of resin is applied to the current collector 34. Further, after the resin injection is completed, when the resin is cooled and molded, a load caused by the thermal contraction of the resin is applied to the outer peripheral edge portion 61. Such pressure and load are also well dispersed by the curved portion 71a. The pressure and the load are generated when the first seal portion 52 and the second seal portion 54 are respectively molded.

  The curved portions 71 a of the plurality of bipolar electrodes 32 included in the stacked body 30 are curved so as to protrude in the same direction. Thereby, a short circuit between the bipolar electrodes 32 caused by the curved portion 71a is prevented.

  In the above comparative example, in order to suppress the above-mentioned problems, it is conceivable to increase the thickness of the current collector 134 and to increase the breaking strength and the like. However, when the thickness of the current collector 134 is increased, the number of bipolar electrodes 132 accommodated in the storage module having the same external dimensions is reduced, and the battery capacity indicating the energy amount of the charge and discharge characteristics of the storage device is reduced. It will In addition, the weight of the power storage device itself also increases. For this reason, when the power storage device is mounted on a vehicle, the fuel consumption performance of the vehicle is reduced. On the other hand, according to the storage module 12 of the present embodiment, the thickness of the current collector 34 can be reduced by providing the curved portion 71 a in the current collector 34. Therefore, weight saving of the power storage device 10 can also be realized.

  The maximum protrusion amount E1 of the curved portion 71a is smaller than the distance between the adjacent current collectors 34 in the stacking direction. For this reason, it can prevent that the curved part 71a contacts in the adjacent current collector 34, and short-circuits.

  The storage module 12 includes the separator 40 provided between the adjacent bipolar electrodes 32 along the stacking direction, and in the horizontal direction, the outer peripheral edge 40a of the separator 40 is the first protrusion point of the curved portion 71a and the first seal It is located between the part 52. For this reason, the separator 40 is positioned between the curved portion 71a and the current collector 34 adjacent in the stacking direction. Therefore, the short circuit between the current collectors 34 is well prevented by the separator 40.

  The curved portion 71 a has a curved shape that protrudes from the negative electrode layer 38 toward the positive electrode layer 36. In the bipolar electrode 32, the negative electrode layer 38 tends to expand more easily than the positive electrode layer 36. For this reason, since a load is easily applied to the current collector 34 from the negative electrode layer 38 side, the load can be efficiently dispersed by the curved portion 71 a having a curved shape projecting toward the positive electrode layer 36 side.

  The curved portion 71a has a wavy shape when viewed in the stacking direction. For this reason, it can suppress that load concentrates on a part of curved part 71a.

  The current collector 34 has a rectangular shape as viewed in the stacking direction, and the long portion 71 is provided on the current collector 34 along the four sides of the current collector 34 as viewed in the stacking direction. Therefore, the load can be dispersed in the entire long portion 71.

  Next, modifications of the above embodiment will be described with reference to FIGS. FIG. 6 (a) is an enlarged sectional view of a main part showing the storage module of the first modification of the embodiment, and FIG. 6 (b) is a main part showing the storage module of the second modification of the embodiment It is an expanded sectional view, and Drawing 6 (c) is an important section expanded sectional view showing an electricity storage module of the 3rd modification of the above-mentioned embodiment.

  As shown in FIG. 6A, the current collector 34A of the first modified example is not provided with a curved portion. Instead, the current collector 34A is bent at the boundary B1. As a result, the current collector 34A is provided with a linear long portion 71A as viewed from the horizontal direction. The long portion 71A is inclined with respect to the horizontal direction, and is closer to the negative electrode layer 38 as it approaches the outer peripheral edge portion 61 in the stacking direction. An angle θ1 formed by an imaginary line V1 along the stacking direction at the boundary B1 and the long portion 71A is, for example, 65 ° or more and 85 ° or less. When the angle θ1 is 60 ° or more, the length of the elongated portion 71A from the negative electrode layer 38 to the first seal portion 52 is sufficient. By setting the angle θ1 to 85 ° or less, it is possible to prevent the current collector 34A from being easily broken at the boundary B1 and its periphery. In such a first modification, when pressure is applied to the current collector 34A at the time of charge and discharge of the storage module 12, bending is easily generated in the long portion 71A. Thus, the load concentrated on the boundary B1 is well dispersed by the long portion 71A. Therefore, the same operation and effect as the above embodiment can be achieved.

  As shown in FIG. 6B, in the long portion 71B of the current collector 34B of the second modified example, a curved portion 71b having a shape different from that of the curved portion 71a of the above embodiment is provided. The curved portion 71 b has a substantially V-shape as viewed from the horizontal direction, and is bent so as to protrude toward the positive electrode layer 36 side. Therefore, a corner is formed by the maximum projecting point P of the curved portion 71b and the periphery thereof. The angle at the maximum projecting point P of the curved portion 71b may be acute or obtuse. The angle θ2 at the maximum projecting point P of the bending portion 71b is, for example, 45 ° or more and 120 ° or less. When the angle θ2 is 45 ° or more, the load can be favorably dispersed by the curved portion 71 b. By setting the angle θ2 to 120 ° or less, the bending portion 71b is favorably compressed. Also in such a second modified example, the same function and effect as the above embodiment can be obtained. In the present specification, bending is assumed to be a form of bending.

  As shown in FIG. 6C, in the elongated portion 71C of the current collector 34C according to the third modification, two of the elongated members arranged in the direction crossing the stacking direction (the X direction in FIG. 6C). A curved portion is provided. Specifically, in the third modified example, the bending portion provided in the long portion 71C includes the first bending portion 71c and the second bending portion 71d located outside the first bending portion 71c in the horizontal direction. Have. More specifically, the first curved portion 71c is provided on the center side of the current collector 34C (that is, on the side of the negative electrode layer 38) than the second curved portion 71d, and the second curved portion 71d is a first curved portion. It is provided closer to the outer peripheral edge portion 61 of the current collector 34C than the curved portion 71c. Each of the first curved portion 71c and the second curved portion 71d is curved in a bow shape when viewed from the horizontal direction, and has a substantially arc shape. The projecting direction of the first curved portion 71c and the projecting direction of the second curved portion 71d are different from each other. Specifically, the first curved portion 71 c has a curved shape that protrudes from the negative electrode layer 38 toward the positive electrode layer 36. The second curved portion 71 d has a curved shape that protrudes from the positive electrode layer 36 toward the negative electrode layer 38. Also in such a third modification, the same function and effect as those of the above embodiment can be obtained. In addition, since loads applied to the first curved portion 71c and the second curved portion 71d can be reduced, breakage of the first curved portion 71c and the second curved portion 71d can be suppressed.

  In the third modification, the thickness T1 of the connecting portion 71e connecting the first curved portion 71c and the second curved portion 71d in the long portion 71C is the positive electrode layer 36 and the negative electrode layer 38 in the current collector 34C. Is thinner than the thickness T2 of the portion provided with. Specifically, the thickness T1 of the connection portion 71e is 50% or more and 95% or less of the thickness T2. By the thickness T1 of the connection portion 71e being 50% or more of the thickness T2, the connection portion 71e can be prevented from being easily broken. When the thickness T1 of the connection portion 71e is 95% or less of the thickness T2, both the first bending portion 71c and the second bending portion 71d are likely to be curved starting from the connection portion 71e.

  In the third modification, the amounts of projection of the first curved portion 71c and the second curved portion 71d along the stacking direction are the same, but may be different from each other. In this case, the amount of projection of the first curved portion 71c is preferably larger than the amount of projection of the second curved portion 71d. Thus, the load generated with the charge / discharge reaction of the storage module 12 tends to be concentrated on the boundary B1, and the load can be favorably dispersed by the first curved portion 71c close to the boundary B1.

  The storage module according to the present invention is not limited to the above-described embodiment and the above-described modification, and various other modifications are possible. In the above-mentioned embodiment and the above-mentioned modification, although all the exposed parts of a current collection object correspond to a long part, it is not restricted to this. FIG. 7 is a schematic plan view showing a storage module of a fourth modification of the embodiment. As shown in FIG. 7, a curved portion 71 a may be formed in a part of the exposed portion 62 in the current collector 34D. In this case, the length from the negative electrode layer 38 to the first seal portion 52 in the exposed portion 62 where the curved portion 71 a is not formed is the same as the distance S 1 between the negative electrode layer 38 and the first seal portion 52. Also in such a fourth modified example, since it is possible to disperse the load at the portion where the curved portion 71a is formed, the same function and effect as the above embodiment can be obtained.

  The above-mentioned embodiment and the above-mentioned modification may be combined suitably. For example, the second and third modifications may be combined. Thus, the exposed portion may be provided with a plurality of curved portions having a substantially V-shape when viewed from the horizontal direction. Alternatively, both the curved portion having a substantially V-shape when viewed in the horizontal direction and the curved portion having a substantially arc shape in the horizontal direction may be provided in the exposed portion.

  In the embodiment and the first modification, the curved portion protrudes from the negative electrode layer toward the positive electrode layer, but the invention is not limited thereto. The curved portion may protrude from the positive electrode layer toward the negative electrode layer. In this case, in the plurality of bipolar electrodes included in the laminated body, each curved portion is curved so as to protrude toward the negative electrode layer side. In addition, the curved portion viewed from the stacking direction may not have a wavy shape. For example, the curved portion viewed from the stacking direction may have a linear shape or a polygonal shape.

  In the embodiment, the first modified example, and the third modified example, the curved portion is provided in a part of the exposed portion, but the present invention is not limited to this. For example, the curved portion may be provided throughout the exposed portion. Further, the curved portion may be provided not only at the exposed portion but also at the outer peripheral edge portion. That is, the curved portion may be provided on the entire uncoated region of the current collector.

  In the first modification, the long portion 71A is positioned closer to the negative electrode layer 38 as it approaches the outer peripheral edge portion 61 in the stacking direction, but is not limited thereto. For example, the elongated portion 71A may be positioned closer to the positive electrode layer 36 as it approaches the outer peripheral edge portion 61 in the stacking direction. In addition, the long portion 71A may be bent not only at the boundary B1 but also at the boundary B2 (see FIG. 5B).

  In the second modification, one corner is formed by the maximum projecting point P of the curved portion 71 b and the periphery thereof, but the present invention is not limited to this. For example, a plurality of corner portions may be provided by bending the curved portion in a U-shape.

  In the third modification, the first curved portion 71c and the second curved portion 71d are provided in the long portion 71B, but three or more curved portions may be provided. Even in this case, it is preferable that the protruding directions of the adjacent curved portions be different from each other. That is, it is preferable that a substantially bellows shape is exhibited by the plurality of curved portions when viewed from the horizontal direction. Thus, when a load is applied to the current collector, the plurality of curved portions are easily compressed, and the load is well dispersed. In addition, even when the plurality of curved portions are provided in the elongated portion, the curved portion closest to the negative electrode layer preferably protrudes from the negative electrode layer toward the positive electrode layer. Thereby, the pressure applied from the negative electrode layer side can be favorably dispersed by the curved portion. In the third modification, the protruding directions of all the curved portions may be the same.

DESCRIPTION OF SYMBOLS 10 electrical storage apparatus 12 electrical storage module 30 laminated body 32 bipolar electrode 34, 34A-34D collector 34a 1st surface 34b 2nd surface 36 positive electrode layer 38 negative electrode Layer 38a: End face, 40: Separator, 40a: Outer peripheral edge, 50: Resin part, 52: First seal part (frame), 52b: Inner peripheral surface, 54: Second seal part, 61: Outer peripheral part, 62: Exposed part, 71, 71A to 71C: Long part, 71a, 71b: Curved part, 71c: First curved part, 71d: Second curved part, 71e: Connected part, B1, B2: Boundary, E1: Maximum Amount of protrusion, P: maximum protrusion point, S1: interval, V1: virtual line, θ1, θ2: angle.

Claims (8)

A storage module comprising a plurality of bipolar electrodes,
Each of the plurality of bipolar electrodes is
It has a plate shape extending in a cross direction intersecting the stacking direction of the plurality of bipolar electrodes, a pair of plate surfaces extending in the cross direction, and a frame disposed around the bipolar electrode in the cross direction A current collector having an outer peripheral edge covered and held by the
A positive electrode layer provided on a first surface which is one plate surface of the pair of plate surfaces of the current collector, and positioned inside the outer peripheral edge portion in the cross direction;
And a negative electrode layer provided on a second surface which is the other plate surface of the pair of plate surfaces of the current collector and located inside the outer peripheral edge in the cross direction,
The current collector is located in the cross direction between the outer peripheral edge and a region where the positive electrode layer of the first surface is provided and a region where the negative electrode layer of the second surface is provided. An exposed part is provided,
The power storage module, wherein the exposed portion is located between the frame and the negative electrode layer in the cross direction, and has a long portion longer than a distance between the frame and the negative electrode layer along the cross direction.   The storage module according to claim 1, wherein the long portion is provided with a curved portion exhibiting a curved shape protruding along the stacking direction.   The storage module according to claim 2, wherein a maximum protrusion amount of the curved portion is smaller than a distance between the adjacent current collectors in the stacking direction. It further comprises a separator provided between the adjacent bipolar electrodes along the stacking direction,
The power storage module according to claim 2, wherein an outer peripheral edge of the separator is located between a maximum projecting point of the curved portion and the frame in the cross direction.   The storage module according to any one of claims 2 to 4, wherein the curved portion has a curved shape that protrudes from the negative electrode layer toward the positive electrode layer. The curved portion has a first curved portion, and a second curved portion positioned outside the first curved portion in the cross direction,
The storage module according to any one of claims 2 to 4, wherein a protruding direction of the first curved portion and a protruding direction of the second curved portion are different from each other.   The storage module according to any one of claims 2 to 6, wherein the curved portion has a wavy shape when viewed from the stacking direction. The current collector has a rectangular shape as viewed in the stacking direction,
The power storage module according to any one of claims 1 to 7, wherein the elongated portion is provided on the current collector along four sides of the current collector as viewed in the stacking direction.

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