Electricity storage device

Abstract

A power storage device (1) is provided with: a power storage element unit having a plurality of power storage elements arranged side by side in a first direction; and an exterior body that accommodates the power storage element unit. The exterior body has an opening at an end portion in a second direction orthogonal to the first direction. The exterior body has a bottom wall portion facing the opening portion and a side wall portion connected to the bottom wall portion. The side wall portion faces the power storage element unit in the first direction and is inclined in a direction away from the bottom wall portion in a direction away from the power storage element unit. The side wall portion has a first vertical surface, which is a plane perpendicular to the first direction, in at least a portion in the second direction of an inner surface facing the power storage element unit in the first direction.

Description

Technical Field

[0001] The present invention relates to a power storage device having an outer casing. Background Art

[0002] In the past, when a box-shaped outer casing opened in one direction was manufactured using a mold such as a casting mold, an inclination was set on the inner side of the mold in order to easily remove the molded product from the mold. As a result, an inclination (inclination) called a demolding inclination was generated on the side wall portion of the outer casing. For example, Patent Document 1 discloses an electrical storage device having a first outer casing that holds one or more electrical storage elements and a second outer casing into which the first outer casing is inserted. The first outer casing has a first longitudinal wall portion that surrounds the outer periphery of the one or more electrical storage elements, and the second outer casing has a second longitudinal wall portion that surrounds the first longitudinal wall portion of the first outer casing. The outer surface of the first longitudinal wall portion becomes an inclined surface, and the inclined surface is inclined farther away from the second longitudinal wall portion as it approaches the inner side of the insertion direction of the first outer casing, and either the outer surface of the first longitudinal wall portion or the inner surface of the second longitudinal wall portion has a protrusion that abuts against either the other.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-72088 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] In the above-mentioned conventional power storage device, the first wall portion of the first outer casing has a demolding slope (inclined outwards), for example, by providing a protrusion on the outer surface of the first longitudinal wall portion, the protrusion abuts against the second longitudinal wall portion of the second outer casing accommodating the first outer casing, thereby suppressing the shaking of the first outer casing. That is, the problem caused by the inclination of the outer surface of the first longitudinal wall portion can be solved.

[0008] However, as in the first longitudinal wall portion described above, in an outer casing including a side wall portion having a demolding slope, the inner surface of the side wall portion is also inclined, and problems caused by the inclined inner surface may occur. Specifically, for example, in a case where a storage element unit having a plurality of storage elements arranged in a row is accommodated inside the outer casing, the end of the storage element unit pushes the inner surface of the side wall portion due to expansion of one or more storage elements. The inner surface is inclined upward in a direction (outward) away from the storage element unit, and thus, the storage element unit is subjected to an upward force from the inner surface. The upward force may cause the storage element unit to deviate (displace) upward, which may become the main cause of the occurrence of an undesirable situation.

[0009] The present invention was completed by the inventors of the present application after paying new attention to the above-mentioned problems, and an object of the present invention is to provide a power storage device having an exterior body and improved reliability.

[0010] Means used to solve problems

[0011] A power storage device according to one embodiment of the present invention comprises: a power storage element unit having a plurality of power storage elements arranged along a first direction; an outer casing accommodating the power storage element unit and having an opening at an end portion in a second direction orthogonal to the first direction, the outer casing comprising: a bottom wall portion opposing the opening in the second direction; a side wall portion connected to the bottom wall portion, opposing the power storage element unit in the first direction, and inclined in a direction separating from the power storage element unit as it moves away from the bottom wall portion, wherein at least a portion in the second direction of an inner side surface of the side wall portion opposing the power storage element unit in the first direction has a plane perpendicular to the first direction, namely a first vertical plane.

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to provide a power storage device having improved reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a perspective view showing the appearance of the power storage device according to the embodiment.

[0015] Figure 2 It is an exploded perspective view of the power storage device according to the embodiment.

[0016] Figure 3 It is an exploded perspective view of the electric storage device unit according to the embodiment.

[0017] Figure 4 It is a cross-sectional view of an exterior body according to the embodiment.

[0018] Figure 5 It is a partially cutaway perspective cross-sectional view showing the structural relationship between the exterior casing and the electric storage device unit according to the embodiment.

[0019] Figure 6 It is a cross-sectional view showing the structural relationship between the electric storage device unit and the side wall portion of the exterior body according to the embodiment. DETAILED DESCRIPTION

[0020] (1) An electric storage device according to one embodiment of the present invention, wherein an electric storage element unit has a plurality of electric storage elements arranged along a first direction; an outer casing that accommodates the electric storage element unit and has an opening at an end portion in a second direction orthogonal to the first direction, the outer casing having: a bottom wall portion that is opposite to the opening in the second direction; a side wall portion that is connected to the bottom wall portion, is opposite to the electric storage element unit in the first direction, and is inclined in a direction away from the electric storage element unit as it moves away from the bottom wall portion, wherein at least a portion in the second direction of an inner side surface of the side wall portion that is opposite to the electric storage element unit in the first direction has a plane that is perpendicular to the first direction, namely, a first vertical surface.

[0021] In the power storage device of this embodiment, the side wall portion that is opposite to the power storage element unit in the arrangement direction of the power storage elements, i.e., the first direction, is inclined in the direction of separation from the power storage element unit as it moves away from the bottom wall portion. However, a plane (first vertical plane) perpendicular to the first direction is provided on the inner side surface of the side wall portion. Thus, even when the power storage element unit expands in the first direction, the side wall portion can use the first vertical plane to push back with a reaction force in a direction parallel to the first direction. According to the power storage device of this embodiment, both the expansion of the power storage element unit and the displacement of the power storage element unit can be suppressed. As a result, the possibility of adverse conditions caused by the displacement of the power storage element unit can be reduced. In this way, the power storage device of this embodiment is a power storage device with high reliability.

[0022] (2) In the power storage device described in (1) above, the power storage element unit may further include an end spacer between the plurality of power storage elements and the side wall portion, and the end spacer may include a plane perpendicular to the first direction, i.e., a second vertical surface, on at least a portion of the side surface opposite to the side wall portion.

[0023] According to this structure, when the storage element unit expands in the first direction, the side wall portion and the storage element unit are in a state of pushing each other in the first direction with the first vertical surface in contact with the second vertical surface. Therefore, the force applied by the storage element unit to the side wall portion is dispersed by the first vertical surface, so that stable expansion suppression can be performed. In addition, the relatively large friction force generated by the large surfaces contacting each other can more reliably suppress the movement of the storage element unit in the direction of separation from the bottom wall. In this way, the storage device of this method is a storage device with higher reliability.

[0024] (3) In the power storage device described in (1) or (2) above, the opening portion is capable of allowing the power storage element unit to be inserted, and an inclined surface can be provided on the inner surface of the side wall portion at a position connected to the first vertical surface in the second direction, and the inclined surface is inclined in a direction of separation from the power storage element unit as it moves away from the bottom wall portion.

[0025] According to this structure, by providing an inclined surface on a part of the inner surface of the side wall portion, the inclined surface functions as a guide when the storage element unit is inserted into the outer casing. As a result, the storage element unit can be efficiently accommodated in the outer casing. "The opening portion can be inserted into the storage element unit" means that as long as the opening portion is opened so that the storage element unit can be inserted, it is sufficient. Even if a slit, a concave-convex portion, etc. for guiding the storage element unit to the inside of the outer casing is formed in the opening portion, the storage element unit can be inserted into the outer casing.

[0026] (4) In the power storage device described in (3) above, the inclined surface may include a first inclined surface provided at an end of the inner side surface that is farther from the bottom wall portion than the end in the second direction.

[0027] According to this structure, when the operation of inserting the storage element unit into the opening portion begins, the first inclined surface functions as an insertion guide. In addition, when the opening portion is facing upward, at the upper end of the side wall portion, the upper end of the first vertical surface is adjacent to the first inclined surface. Therefore, the position of the first vertical surface in the first direction is a position farther from the outer surface of the side wall portion. As a result, even when the side wall portion is relatively thin, it is possible to ensure that the thickness of the side wall portion at the end of the first vertical surface closest to the bottom wall portion is a thickness that meets requirements such as safety. In this way, the storage device of this method is a storage device with higher reliability.

[0028] (5) In the power storage device described in (3) or (4) above, the inclined surface may include a second inclined surface provided at an end portion closer to the bottom wall portion among both end portions of the inner surface in the second direction.

[0029] According to this structure, by providing the second inclined surface at a position close to the bottom wall portion on the inner side surface of the side wall portion, it is possible to ensure that the wall thickness of the side wall portion at the position of the end of the second direction of the first vertical surface is a thickness that meets the requirements of safety, etc. In this way, the power storage device of this embodiment is a power storage device with higher reliability. In addition, the second inclined surface also serves as an insertion guide when the operation of inserting the power storage element unit into the outer casing is completed.

[0030] Hereinafter, an embodiment of the present invention (including its modified examples) of the power storage device will be described with reference to the accompanying drawings. The embodiments described below all represent general examples or specific examples. The numerical values, shapes, materials, structural members, configuration positions and connection methods of structural members, manufacturing processes, the order of manufacturing processes, etc. shown in the following embodiments are examples and are not intended to limit the present invention. In each figure, dimensions, etc. are not strictly illustrated. In each figure, the same or identical structural members are marked with the same figure marks.

[0031] In the following description and drawings, the opposing direction of the short side of the storage element or the length direction of the cover of the container of the storage element is defined as the Y-axis direction. The arrangement direction of a plurality of storage elements or the opposing direction of the long side of the storage element is defined as the X-axis direction. The arrangement direction or the up-down direction of the main body (external body main body) and the cover of the outer casing of the storage device is defined as the Z-axis direction. These X-axis direction, Y-axis direction and Z-axis direction are directions that intersect each other (orthogonal in this embodiment). Depending on the usage, the case where the Z-axis direction is not the up-down direction is also considered, but for the convenience of explanation below, the Z-axis direction is used as the up-down direction for explanation.

[0032] In the following description, for example, the positive direction of the X-axis indicates the direction of the arrow of the X-axis, and the negative direction of the X-axis indicates the direction opposite to the positive direction of the X-axis. The same is true for the Y-axis direction and the Z-axis direction. When simply referred to as "the X-axis direction", it means two directions or any one direction parallel to the X-axis. The same is true for the terms Y-axis and Z-axis.

[0033] Furthermore, expressions indicating relative directions or postures such as parallel and orthogonal also include situations where the directions or postures are not the directions or postures, strictly speaking. For example, two directions being orthogonal not only means that the two directions are completely orthogonal, but also means that they are substantially orthogonal, i.e., including a difference of, for example, a few percent. In the following description, when "insulated" is expressed, it means "electrical insulation".

[0034] (Implementation Method)

[0035] [1. Overall Description of the Power Storage Device]

[0036] First, a schematic configuration of a power storage device 1 according to the embodiment will be described. Figure 1 It is a perspective view showing the appearance of the power storage device 1 according to the embodiment. Figure 2 It is an exploded perspective view of the power storage device 1 according to the embodiment. Figure 3 This is a perspective exploded view of the power storage element unit 20 of the embodiment. Figure 2 In addition to the components shown in the subsequent drawings, other components such as sensors for measuring temperature and voltage and wires connected to the sensors are also accommodated, but the illustration and description of these components are omitted.

[0037] The power storage device 1 is a device that can be charged with electricity from the outside and can discharge to the outside. The power storage device 1 is, for example, a battery module (battery pack) used for power storage or power supply. Specifically, the power storage device 1 is used as a battery for driving or starting an engine of a mobile body such as a car, a motorcycle, a watercraft, a ship, a power sled, agricultural machinery, construction machinery, or a railway vehicle for an electric railway. As the above-mentioned car, an electric car (EV), a hybrid electric car (HEV), a plug-in hybrid electric car (PHEV) and a fossil fuel (gasoline, light oil, liquefied natural gas, etc.) car can be exemplified. As the railway vehicle for the above-mentioned electric railway, a tram, a monorail, a linear motor car and a hybrid electric car with a diesel engine and an electric motor can be exemplified. The power storage device 1 can also be used as a battery for a fixed installation used in a home or business.

[0038] like Figure 1 and Figure 2 As shown, the power storage device 1 includes an exterior body 10 and a power storage element unit 20 accommodated in the exterior body 10. Above the power storage element unit 20, a bus bar holder 30 for holding a bus bar 60 joined to the power storage element 100 is arranged.

[0039] The outer casing 10 is a box-shaped container (module housing) constituting the frame of the power storage device 1. The outer casing 10 is arranged outside the power storage element unit 20 and the bus bar holder 30, fixes them at a predetermined position, and protects them from impact, etc. In the present embodiment, the outer casing 10 is formed of a metal such as iron, aluminum, or an aluminum alloy. The general shape of the outer casing 10 (each of the outer casing body 12 and the cover body 11) is formed by casting using a mold. As a material for forming the outer casing 10, in addition to metal, resin, etc. can also be used. Examples of the resin include polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyetheretherketone (PEEK), tetrafluoroethylene-perfluoroalkylvinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polyamide (PA) or ABS resin.

[0040] The outer casing 10 has: an opening portion 12a, which is provided at one of the two ends in the Z-axis direction and can accommodate the storage element unit 20 to be inserted; and a bottom wall portion 19, which is provided at a position opposite to the opening portion 12a. Specifically, the outer casing 10 has an outer casing body 12 and a cover body 11, and the opening portion 12a and the bottom wall portion 19 are provided in the outer casing body 12. The outer casing body 12 is a bottomed rectangular cylindrical shell formed with an opening portion 12a, and accommodates the storage element unit 20. The outer casing body 12 has four side wall portions, such as a side wall portion 15 that separates the inside and the outside of the outer casing 10. The storage element unit 20 is surrounded by the four side wall portions of the outer casing body 12 inside the outer casing 10. Among the four side wall portions, a pair of side wall portions 13 are arranged at a position opposite to the storage element unit 20 in the X-axis direction. A first vertical surface 16 (see FIG. 1 ) orthogonal to the X-axis direction is provided on the inner side surface of the side wall portion 13. Figure 2 ). The effect of the first vertical surface 16 will be described later. Figures 4 to 6 The outer casing 10 may include an exhaust pipe or the like for exhausting the gas inside the outer casing 10 to the outside. Figure 1 and Figure 2 Components not shown in the figure.

[0041] The cover 11 is a rectangular member that blocks the opening 12a of the outer body main body 12. The cover 11 is joined to the outer body main body 12 by a plurality of bolts 41, whereby the cover 11 is fixed to the outer body main body 12. Specifically, a through hole 43 through which the bolts 41 pass is provided at the peripheral portion of the cover 11, and a fixing hole portion 42 is provided at the peripheral portion of the opening 12a of the outer body main body 12, that is, the opening peripheral portion 12b. The bolt 41 is screwed into the fixing hole portion 42 of the outer body main body 12 while passing through the through hole 43 of the cover 11. Thus, the cover 11 is joined to the opening peripheral portion 12b of the outer body main body 12.

[0042] The storage element unit 20 includes a plurality of storage elements 100 and a spacer 130 disposed along each of the plurality of storage elements 100. The storage element 100 is a secondary battery (single cell) that can be charged and discharged, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. Figure 3 As shown, the storage element 100 has a flat rectangular (square) container 110 and a pair of (positive and negative) electrode terminals 120 fixed to the container 110. An electrode body, a current collector, an electrolyte, etc., not shown in the figure, are contained inside the container 110. As an electrode body of the storage element 100, a wound electrode body is exemplified in which an electrode body arranged in a layered state with a separator sandwiched between a positive electrode plate and a negative electrode plate is wound. The storage element 100 may have a stacked (stacked) electrode body formed by stacking a plurality of flat plate-shaped electrode plates or a corrugated electrode body in which the electrode plates are folded into a corrugated shape.

[0043] The storage element 100 is not limited to a non-aqueous electrolyte secondary battery, and may be a secondary battery other than a non-aqueous electrolyte secondary battery, or may be a capacitor. The storage element 100 may not be a secondary battery, but a primary battery that can use the stored electrical energy even if the user does not charge it. The storage element 100 may also be a battery using a solid electrolyte. The storage element 100 may also be a bag-type storage element. The shape of the storage element 100 is not limited to the above-mentioned square, and may also be a polygonal prism shape, a cylindrical shape, an elliptical cylindrical shape, a long cylindrical shape, etc.

[0044] In this embodiment, if Figure 3 As shown, the container 110 includes a container body 111 and a cover plate 112 that blocks the opening of the container body 111. The container 110 is a structure in which the electrode body and the like are housed inside the container body 111, and the container body 111 and the cover plate 112 are joined by welding or the like, thereby forming an internally sealed structure. The material of the container 110 (container body 111 and cover plate 112) is not particularly limited, and a metal that can be welded (joined) such as stainless steel, aluminum, aluminum alloy, iron, and electroplated steel plate can be used, and a resin can also be used.

[0045] The container body 111 has a pair of long side surfaces 110a, a pair of short side surfaces 110b, and a bottom surface 110c disposed at a position opposite to the cover plate 112. The positive and negative electrode terminals 120 and the gas discharge valve 105 are disposed on the cover plate 112. The gas discharge valve 105 is a portion that opens when the internal pressure of the container 110 rises excessively, thereby discharging the gas inside the container 110 to the outside. In the storage element unit 20, each of the plurality of storage elements 100 is arranged in a posture with the long side surface 110a facing the arrangement direction (X-axis direction) and the electrode terminal 120 facing the positive direction of the Z-axis. In the present embodiment, the X-axis direction is an example of a first direction, and the Z-axis direction is an example of a second direction orthogonal to the first direction. For example, the outer body 10 is described as having an opening 12a at one of the two ends in the second direction.

[0046] The storage element unit 20 has twelve storage elements 100 configured as described above. In the present embodiment, each of the twelve storage elements 100 is arranged between two upper spacers 130. The storage element unit 20 of the present embodiment has thirteen spacers 130. In the case of distinguishing a pair of spacers 130 located at both ends of the spacers 130 in the X-axis direction from other spacers, they are marked as end spacers 131. In the case of distinguishing a spacer 130 located between two adjacent storage elements 100 from other spacers, they are marked as inter-cell spacers 132.

[0047] In this embodiment, the spacer 130 has a function of insulating the container 110 of the energy storage element 100 from other conductive members adjacent to the energy storage element 100 (including the container 110 of other energy storage elements 100), and also has a function of holding the energy storage element 100 through a plurality of faces extending in mutually intersecting directions. The spacer 130 may also be referred to as a "holder" or "cell holder", etc. The end spacer 131 may also be referred to as an "end holder".

[0048] The spacer 130 is formed of any of the resin materials having electrical insulation properties that can be used as the material of the outer casing 10. The spacer 130 is preferably formed of a resin material having a volume resistivity of 1×10 10 In this embodiment, the end spacer 131 has a second vertical surface 140 at a position opposite to the first vertical surface 16 of the side wall portion 13 of the outer body 10. The effects of the second vertical surface 140 will be described later. Figures 4 to 6 Give a narrative.

[0049] The busbar holder 30 is arranged opposite to the cover plate 112 of the storage element 100, and is a flat rectangular insulating member that holds a plurality of busbars 60. The busbar holder 30 is formed, for example, of any of the resin materials having electrical insulation properties that can be used as the material of the above-mentioned outer casing 10. The busbar 60 arranged in the busbar holder 30 is positioned relative to the electrode terminal 120 that is the object of joining, and in this state, is joined to the electrode terminal 120 by, for example, laser welding. In this embodiment, among the twelve storage elements 100 included in the storage element unit 20, three storage elements 100 arranged in succession are connected in parallel by the busbar 60. Thus, four groups of storage elements 100 connected in parallel are formed. The four groups of storage elements 100 are connected in series by three busbars 60.

[0050] The electrode terminals 120 of the storage elements 100 at the two end groups of the four storage elements 100 connected in series are the positive electrode (total positive terminal) and the negative electrode (total negative terminal) of the storage element unit 20. In the present embodiment, the electrode terminal 120 of the positive electrode of the group (three) of the storage elements 100 at the end in the negative direction of the X axis among the twelve storage elements 100 is the positive electrode (total positive terminal) of the storage element unit 20. The electrode terminal 120 of the negative electrode of the group (three) of the storage elements 100 at the end in the positive direction of the X axis among the twelve storage elements 100 is the negative electrode (total negative terminal) of the storage element unit 20.

[0051] Although not shown in the figure, the side wall portion 15 of the outer casing 10 is provided with an opening through which the ends of the bus bars 60 connected to the positive and negative electrodes of the storage element unit 20 pass. The ends of the two bus bars 60 are exposed to the outside of the outer casing 10 through the opening provided in the side wall portion 15 (see Figure 1 ) and function as a positive external terminal and a negative external terminal of the power storage device 1.

[0052] A control device and electrical equipment such as relays for controlling the charging state of the plurality of storage elements 100 included in the storage element unit 20 may be arranged inside the outer casing 10. In this case, the storage device 1 may have a positive external terminal and a negative external terminal fixed to the cover 11, that is, a positive external terminal and a negative external terminal electrically connected to the storage element unit 20 via the electrical equipment and the bus bar 60.

[0053] The electrical connection method of the twelve storage elements 100 by the bus bar 60 is not limited to the above method, and all twelve storage elements 100 may be connected in series by a plurality of bus bars 60. The number of storage elements 100 included in the storage element unit 20 is not limited to twelve. The number of storage elements 100 included in the storage element unit 20 may be two or more.

[0054] In the thus constructed power storage device 1, the manufacturing process of the outer casing 10 includes a molding process (casting process) using a casting mold, and the outer casing 10 has an inclined side wall portion 13. Specifically, in the outer casing main body 12 which is a box-shaped structure having an opening portion 12a, the side wall portion 13 which is opposite to the power storage element unit 20 in the X-axis direction is inclined outward. As described above, if the power storage element unit 20 expands along the X-axis direction and presses the side wall portion 13, the side wall portion 13 can be changed to a state of applying an upward reaction force to the power storage element unit 20. However, in the outer casing 10 of the present embodiment, the side wall portion 13 has a structure that makes it difficult to generate such a reaction force. Below, with the side wall portion 13 and the structure of its periphery as the center, reference will be made to the following. Figures 4 to 6 The power storage device 1 according to the embodiment will be described.

[0055] [2. Regarding the structure of the side wall and its surroundings]

[0056] Figure 4 1 is a cross-sectional view of the outer casing 10 according to the embodiment. Figure 4 In the figure, the outer body main body 12 of the outer body 10 is shown along Figure 2 In the cross section taken along line IV-IV, the cover body 11 is omitted from illustration. Figure 5 1 is a partially cutaway perspective cross-sectional view showing the structural relationship between the outer casing 10 and the electric storage element unit 20 of the embodiment. Figure 5In the figure, the outer casing 10 containing the electric storage element unit 20 is shown. Figure 2 This is a stereogram of the state cut along the XZ plane along line IV-IV. Figure 6 2 is a cross-sectional view showing the structural relationship between the power storage element unit 20 and the side wall portion 13 of the exterior body 10 according to the embodiment. Figure 6 In the figure, the outer body main body 12 and the end spacer 131 are shown. Figure 4 The cross section at the same position simply illustrates the side surface of the storage element 100 viewed from the negative direction of the Y axis. Only the end spacer 131 at the end of the storage element unit 20 in the positive direction of the X axis and one storage element 100 arranged along the end spacer 131 are illustrated, and the illustration of other spacers 130 and storage elements 100 is omitted.

[0057] In the present embodiment, each of the pair of side wall portions 13 facing each other in the X-axis direction has the same structure as each other (see Figure 4 Hereinafter, the structure of the side wall portion 13 in the positive direction of the X axis and its surroundings of the pair of side wall portions 13 will be described, and the description of the side wall portion 13 in the negative direction of the X axis will be omitted.

[0058] like Figures 4 to 6 As shown, the outer casing body 12 of the outer casing 10 is a shell that accommodates the storage element unit 20. The outer casing body 12 has a pair of side wall portions 13 that are opposite to each other in the arrangement direction (stacking direction) of the storage element 100 in the storage element unit 20, that is, in the X-axis direction. In the present embodiment, the outer casing 10 is formed of a metal such as iron, aluminum or an aluminum alloy. Specifically, the manufacture of the outer casing body 12 includes a casting process, and a plurality of wall portions (including a pair of side wall portions 13) extending from the bottom wall portion 19 in the positive direction of the Z axis have a demolding slope (inclination).

[0059] like Figure 6 As shown, when the bottom wall 19 is arranged in a posture parallel to the XY plane, the angle (inclination angle) between the bottom wall 19 and the side wall 13 is ) is greater than 90°. In this embodiment, the inclination angle The reference surface of the bottom wall portion 19 is the inner bottom surface 19a of the bottom wall portion 19, and the reference surface of the side wall portion 13 is the outer side surface 13b. In the cross section parallel to the XZ plane, the angle (inclination angle) formed by the inner bottom surface 19a of the bottom wall portion 19 and the outer side surface 13b of the side wall portion 13 is ) can be greater than 90°.

[0060] Thus, the side wall portion 13 in the positive direction of the X axis is inclined in a direction away from the power storage element unit 20 (in the positive direction of the X axis) as it moves away from the bottom wall portion 19 (in the positive direction of the Z axis). The side wall portion 13 is inclined outward.

[0061] More specifically, immediately after the outer casing main body 12 is removed from the mold, the inner side surface 13a and the outer side surface 13b (see Figure 6 ) are all inclined surfaces that are inclined outward as a whole. Assume that the entire area of ​​the inner side surface 13a is an inclined surface. In this case, the energy storage element unit 20 expands in the X-axis direction due to the expansion of more than one energy storage element 100. As a result, if the inner side surface 13a of the side wall portion 13 is pressed by the end of the energy storage element unit 20, the reaction force of the side wall portion 13 generates a component in the positive direction of the Z-axis. The reaction force includes a component that lifts the end of the energy storage element unit 20 upward. The greater the expansion of the energy storage element unit 20 in the X-axis direction, the greater the reaction force that lifts the end upward, and the energy storage element unit 20 may be displaced upward. If the end of the energy storage element unit 20 is displaced upward, it is possible that the connection between the energy storage element unit 20 and other components such as the bus bar 60 is damaged.

[0062] In the side wall portion 13 of the present embodiment, a first vertical surface 16 perpendicular to the arrangement direction (X-axis direction) of the storage element 100 in the storage element unit 20 is provided on at least a portion of the inner side surface 13a. Specifically, the first vertical surface 16 is provided at a position of the inner side surface 13a that is opposite to the storage element unit 20 in the X-axis direction. Thus, when the storage element unit 20 expands in the X-axis direction (when the entire length in the X-axis direction is extended), the end of the storage element unit 20 in the X-axis direction presses the first vertical surface 16. The first vertical surface 16 pressed in the X-axis direction by the storage element unit 20 can push the storage element unit 20 back by a reaction force in a direction parallel to the X-axis direction. Thus, the upward displacement of the storage element unit 20 can be suppressed. Such a first vertical surface 16 is formed, for example, by cutting the inner side surface 13a of the side wall portion 13.

[0063] In this embodiment, the inner side surface 13a of the side wall portion 13 is formed substantially parallel to the outer side surface 13b of the side wall portion 13 except for the first vertical surface 16. The reference surface of the side wall portion 13 is Figure 6 The reference plane is the outer side surface 13b, but the reference plane may also be the inner side surface 13a. The inner side surface 13a has an inclination angle θ with respect to the direction perpendicular to the X-axis direction (reference direction) (see Figure 6 ), the inclination angle of the side wall portion 13 The inclination angle of the inner side surface 13a is θ+90°. It is also possible that the inclination angle of the side wall portion 13 relative to the reference direction is θ. Similarly, the inclination angle of the side wall portion 13 is The reference surface of the bottom wall portion 19 is also the same, the inner bottom surface 19a and the outer bottom surface 19b of the bottom wall portion 19 (see Figure 6) are parallel, therefore, the reference plane may not be the inner bottom surface 19a but the outer bottom surface 19b.

[0064] As described above, the power storage device 1 of one embodiment of the present invention includes: the power storage element unit 20, which includes a plurality of power storage elements 100 arranged in a first direction, i.e., the X-axis direction; and the outer casing 10, which accommodates the power storage element unit 20. The outer casing 10 has an opening 12a at an end in the second direction, i.e., the Z-axis direction, which is orthogonal to the X-axis direction. The outer casing 10 includes a bottom wall 19 that faces the opening 12a and a side wall 13 that is connected to the bottom wall 19. The side wall 13 faces the power storage element unit 20 in the X-axis direction, and is inclined in a direction away from the power storage element unit 20 as it moves away from the bottom wall 19. At least a portion of the inner side surface 13a of the side wall 13 that faces the power storage element unit 20 in the X-axis direction in the Z-axis direction includes a first vertical surface 16 that is a plane perpendicular to the X-axis direction.

[0065] Thus, in the energy storage device 1 of the present embodiment, the side wall portion 13 that is opposite to the energy storage element unit 20 in the arrangement direction of the energy storage element 100, that is, in the X-axis direction, is inclined in a direction away from the energy storage element unit 20 as it moves away from the bottom wall portion 19. That is, due to the manufacturing method using a mold such as a casting mold, the inner side surface 13a and the outer side surface 13b of the side wall portion 13 are inclined outward as a whole. However, a plane (first vertical surface 16) perpendicular to the X-axis direction is provided on the inner side surface 13a of the side wall portion 13. Therefore, in the case where the energy storage element unit 20 expands in the X-axis direction and presses the side wall portion 13, as shown in FIG. Figure 6 As shown, the pressing force F1 acts on the first vertical surface 16 along the normal direction of the first vertical surface 16 (the direction parallel to the X-axis direction). As a result, the side wall portion 13 can push back with a reaction force F2 in a direction parallel to the X-axis direction. Thus, the magnitude of the upward (Z-axis positive direction) component included in the reaction force of the side wall portion 13 can be suppressed. The reaction force F2 of the side wall portion 13 acts efficiently on the storage element unit 20 as a force to suppress the expansion of the storage element unit 20 that wants to expand in the X-axis direction. According to the storage device 1 of this embodiment, the expansion of the storage element unit 20 can be suppressed, and the displacement of the storage element unit 20 can be suppressed. As a result, the possibility of a malfunction caused by the displacement of the storage element unit 20 is reduced. The storage device 1 of this embodiment is a highly reliable storage device.

[0066] In more detail, the first vertical surface 16 does not have to be strictly perpendicular to the X-axis direction. The inner side surface 13a of the side wall portion 13 inclined due to the demolding slope has an inclination angle θ relative to the direction perpendicular to the X-axis direction (reference direction) (see Figure 6), the inclination angle of the first vertical plane 16 relative to the reference direction is less than θ. If the inclination angle of the first vertical plane 16 relative to the reference direction is smaller than the inclination angle of the inner side surface 13a, the component of the reaction force of the side wall portion 13 in the positive direction of the Z axis becomes smaller than the case where the first vertical plane 16 does not exist on the inner side surface 13a. The storage element unit 20 is not easy to displace in the positive direction of the Z axis. The inclination angle caused by the demolding slope is usually about 1° to 3°. Therefore, if the inclination angle of the first vertical plane 16 relative to the reference direction is less than θ, it can be essentially expressed as the first vertical plane 16 is parallel to the reference direction, that is, perpendicular to the X-axis direction.

[0067] In this embodiment, the energy storage device unit 20 includes an end spacer 131 between the plurality of energy storage devices 100 and the side wall 13. The end spacer 131 has a second vertical surface 140 which is a plane perpendicular to the X-axis direction on at least a portion of a side surface facing the side wall 13.

[0068] In this embodiment, if Figure 3 , Figure 5 and Figure 6 As shown, the end spacer 131 forms a second vertical surface 140 by the end surface in the X-axis direction of the portion protruding from the spacer body 134 in the X-axis direction. The second vertical surface 140 has a plurality of recessed portions 140a formed by weight reduction processing for weight reduction, etc., and as a result, a grid-like surface is arranged on the end spacer 131 as the second vertical surface 140. In this way, the second vertical surface 140 arranged on the end spacer 131 is arranged to face the first vertical surface 16 in the X-axis direction in a state where the storage element unit 20 is accommodated in the exterior body 10.

[0069] According to this structure, if the storage element unit 20 expands in the X-axis direction, Figure 6 As shown, the side wall portion 13 and the energy storage element unit 20 are in a state of pushing each other in the X-axis direction with the first vertical surface 16 and the second vertical surface 140 in surface contact. Therefore, the force applied by the energy storage element unit 20 to the side wall portion 13 is dispersed by the first vertical surface 16, so that stable expansion suppression can be performed. The relatively large friction force generated by the large surfaces in contact with each other can more reliably suppress the movement of the energy storage element unit 20 in the direction of separation from the bottom wall portion 19.

[0070] In this embodiment, the opening portion 12a allows the storage element unit 20 to be inserted, and on the inner surface 13a of the side wall portion 13, an inclined surface 17 is provided at a position continuous with the first vertical surface 16 in the Z-axis direction, which is inclined in a direction away from the storage element unit 20 as it moves away from the bottom wall portion 19.

[0071] According to this configuration, by providing the inclined surface 17 on a part of the inner surface 13a of the side wall portion 13, the inclined surface 17 functions as a guide when inserting the power storage device unit 20 into the exterior body 10. Thus, the power storage device unit 20 can be efficiently housed in the exterior body 10.

[0072] The inclined surface 17 is formed based on, for example, a draft angle. That is, in the inner side surface 13a of the side wall portion 13, the portion other than the first vertical surface 16 formed by cutting or the like maintains the original draft angle (inclination). Thus, the inclined surface 17 is provided on a portion of the inner side surface 13a.

[0073] In the present embodiment, the inclined surface 17 includes a first inclined surface 17a provided at an end of the inner side surface 13a in the Z-axis direction that is farther from the bottom wall portion 19. In other words, the inclined surface 17 includes a first inclined surface 17a provided at an end of the inner side surface 13a in the Z-axis direction. This end is an end of the inner side surface 13a in the Z-axis direction that is farther from the bottom wall portion 19.

[0074] According to this structure, the first inclined surface 17a functions as an insertion guide when the operation of inserting the storage element unit 20 into the opening 12a begins. Figure 6 As shown, the first inclined surface 17a is formed first, and then the first vertical surface 16 is formed. The position of the first vertical surface 16 in the X-axis direction is far from the outer side surface 13b of the side wall portion 13. Even if the side wall portion 13 is relatively thin, the thickness of the side wall portion 13 at the end of the first vertical surface 16 closest to the bottom wall portion 19 can be ensured to be a thickness that meets the requirements of safety and the like.

[0075] In the present embodiment, the inclined surface 17 includes a second inclined surface 17b provided at an end portion of the inner side surface 13a in the Z-axis direction that is closer to the bottom wall portion 19. That is, the inclined surface 17 includes a second inclined surface 17b provided at an end portion of the inner side surface 13a in the Z-axis direction. This end portion is an end portion of the inner side surface 13a in the Z-axis direction that is closer to the bottom wall portion 19.

[0076] When only the first vertical surface 16 but no second inclined surface 17b exists until the bottom wall 19 is reached, the wall thickness of the side wall 13 at the lower end of the first vertical surface 16 becomes thinner. In view of this, in the present embodiment, the second inclined surface 17b is provided at the end of the inner side surface 13a close to the bottom wall 19. Thus, the wall thickness of the side wall 13 at the lower end of the first vertical surface 16 can be ensured to be a thickness that satisfies safety requirements. The second inclined surface 17b also functions as an insertion guide when the operation of inserting the storage element unit 20 into the outer casing 10 is completed.

[0077] [3. Modifications]

[0078] The power storage device 1 according to the embodiment of the present invention has been described above, but the present invention is not limited to this embodiment. The embodiments disclosed herein are illustrative in all respects and are not restrictive, and the scope of the present invention includes all modifications within the meaning and scope equivalent to the claims.

[0079] The inclined surface 17 may not be provided on the inner side surface 13a of the side wall portion 13. The first vertical surface 16 may not be provided over the entire region of the inner side surface 13a in the Z-axis direction. Even in this case, if the wall thickness of the side wall portion 13 is relatively thick before the first vertical surface 16 is formed, the thickness of the side wall portion 13 at the position of the lower end of the first vertical surface 16 can be ensured to be a thickness that satisfies requirements such as safety.

[0080] In the present embodiment, each of the pair of side wall portions 13 facing each other in the X-axis direction has the same structure, but these side wall portions 13 may have different structures. One of the pair of side wall portions 13 may have the first vertical surface 16, and the other side wall portion 13 may not have the first vertical surface 16. Even in this case, at least the end facing the first vertical surface 16 of the two ends of the storage element unit 20 in the X-axis direction is unlikely to be displaced upward due to the reaction force of the side wall portion 13.

[0081] The portion of the inner side surface 13a of the side wall portion 13 other than the first vertical surface 16 may not be parallel to the outer side surface 13b of the side wall portion 13. In this case, it can be expressed that if the outer side surface 13b is inclined, the side wall portion 13 is inclined. The side wall portion 13 in the positive direction of the X axis (see Figure 6 ), the outer side surface 13b is inclined in the direction of separation from the storage element unit 20 (the positive direction of the X axis) as it moves away from the bottom wall portion 19 (advancing in the positive direction of the Z axis). Therefore, in this case, the side wall portion 13 can be shown to be inclined in the direction of separation from the storage element unit 20 (inclined outward) as it moves away from the bottom wall portion 19.

[0082] The inclination angle of the first inclined surface 17a in the inner side surface 13a of the side wall portion 13 relative to the reference direction may be different from the inclination angle of the second inclined surface 17b relative to the reference direction. By performing cutting processing on the first inclined surface 17a having a demolding slope of about 1° to 3°, the inclination angle of the first inclined surface 17a relative to the reference direction can be changed to an angle greater than 3°. As a result, the insertion of the storage element unit 20 into the outer casing 10 becomes easier.

[0083] The second vertical surface 140 of the end spacer 131 may not have the recessed portion 140a formed by the lightening process. The second vertical surface 140 may be a simple flat surface without projections and recesses.

[0084] The size and shape of the first vertical surface 16 need not be Figure 2 , Figure 4 and Figure 6 The size and shape shown in the figure. The first vertical surface 16 can also be set on the inner side surface 13a of the side wall portion 13 in the entire area of ​​the Y-axis direction. The first vertical surface 16 can also be formed in a stepped shape instead of a single plane. The first vertical surface 16 can also include two planes perpendicular to the X-axis direction, that is, a plane close to the storage element unit 20 and a plane far from the storage element unit 20. In this case, these two planes can also be referred to as "first vertical planes". The side wall portion 13 can also have a plurality of first vertical planes with different positions in the X-axis direction. Even in this case, if a portion that can be in surface contact with both of the two first vertical planes is formed at the end of the storage element unit 20 opposite to the side wall portion 13, the side wall portion 13 can apply a reaction force in a direction substantially parallel to the X-axis to the storage element unit 20. The expansion of the storage element unit 20 can be suppressed, and the displacement of the storage element unit 20 can be suppressed.

[0085] In the present embodiment, the width of the first vertical surface 16 in the Y-axis direction is greater than the width of the second vertical surface 140 of the end spacer 131 in the Y-axis direction that is in direct contact with the first vertical surface 16. Moreover, the width of the first vertical surface 16 in the Z-axis direction is substantially the same as the width of the second vertical surface 140 of the end spacer 131 in the Z-axis direction. Thus, the first vertical surface 16 can be in contact with substantially the entire area of ​​the second vertical surface 140, thereby being able to effectively suppress the expansion of the energy storage element unit 20 in the X-axis direction. However, the width of the first vertical surface 16 in the Z-axis direction may also be smaller than the width of the second vertical surface 140 in the Z-axis direction. Figure 6 In the embodiment, the first inclined surface 17a may be arranged in the region from the upper end of the side wall portion 13 to the position opposite to the second vertical surface 140 in the X-axis direction. A part of the second vertical surface 140 may not be in contact with the first vertical surface 16. However, from the viewpoint of effectively suppressing the expansion of the storage element unit 20, it is preferred that Figure 6 At a position facing the center portion of the container 110 of the energy storage element 100 in the Z-axis direction, the first vertical plane 16 and the second vertical plane 140 are arranged to face each other in the X-axis direction.

[0086] The storage element unit 20 may not include the plurality of spacers 130. When the storage element 100 at the axial end of the storage element unit 20 includes an insulating member covering the outer surface of the container 110, the long side surface 110a of the container 110 (see Figure 3 ) may be in contact with the first vertical surface 16 of the side wall portion 13. When the outer casing 10 is formed of a non-metallic resin such as PP or PE, the long side surface 110a of the container 110 may be in direct contact with the first vertical surface 16 of the side wall portion 13.

[0087] like Figure 3 As shown, each of the plurality of spacers 130 may not have a shape that holds the energy storage element 100 by a plurality of surfaces. Each of the plurality of spacers 130 may be a simple flat plate-shaped member disposed along the long side surface 110 a of the energy storage element 100 .

[0088] The storage element unit 20 may include not only the plurality of storage elements 100 and the plurality of spacers 130, but also the plurality of bus bars 60 and the bus bar holder 30 (see FIG. 1 ) that are joined to the electrode terminals 120 of the plurality of storage elements 100. Figure 2 ) The structure in which the bus bar holder 30 and the plurality of bus bars 60 are added to the electric storage element unit 20 of the embodiment may also be referred to as an "electric storage element unit".

[0089] Any configuration in which the components included in the above-described embodiment and its modified examples are arbitrarily combined is also within the scope of the present invention.

[0090] The present invention can be applied to a power storage device having a power storage element such as a lithium ion secondary battery.

[0091] Description of reference numerals:

[0092] 1 Power storage device

[0093] 10 outer body

[0094] 12 Main body of outer body

[0095] 12a Opening

[0096] 13, 15 side wall

[0097] 13a Inner side

[0098] 13b Outer side

[0099] 16 First vertical plane

[0100] 17 Inclined surface

[0101] 17a First inclined surface

[0102] 17b Second inclined surface

[0103] 19 Bottom wall

[0104] 19a Inner bottom surface

[0105] 19b Outer bottom

[0106] 20 Storage element unit

[0107] 100 Storage Components

[0108] 110 Container

[0109] 110a Long side

[0110] 110b Short side

[0111] 110c bottom

[0112] 130 Spacer

[0113] 131 End spacer

[0114] 140 Second vertical plane

[0115] 140a recess

Claims

1. A power storage device, wherein: have: The power storage element unit comprises a plurality of power storage elements arranged along a first direction; an outer casing that accommodates the electric storage element unit and has an opening at an end portion in a second direction orthogonal to the first direction, The outer casing has: a bottom wall portion, opposite to the opening portion in the second direction; a side wall portion connected to the bottom wall portion, facing the power storage element unit in the first direction, and inclined in a direction away from the power storage element unit as it moves away from the bottom wall portion, At least a portion of the inner side surface of the side wall portion in the second direction that faces the electric storage element unit in the first direction has a first vertical surface that is a plane perpendicular to the first direction.

2. The power storage device according to claim 1, wherein The energy storage element unit further includes an end spacer between the plurality of energy storage elements and the side wall portion. The end spacer has a second vertical surface that is a plane perpendicular to the first direction at at least a portion of a side surface facing the side wall portion.

3. The power storage device according to claim 1 or 2, wherein: The opening is capable of being inserted with the storage element unit. An inclined surface is provided on the inner side surface of the side wall portion at a position connected to the first vertical surface in the second direction, and the inclined surface is inclined in a direction away from the power storage element unit as it moves away from the bottom wall portion.

4. The power storage device according to claim 3, wherein: The inclined surface includes a first inclined surface provided at an end portion of the inner side surface that is farther from the bottom wall portion than the end portions in the second direction.

5. The power storage device according to claim 3, wherein: The inclined surface includes a second inclined surface provided at an end portion closer to the bottom wall portion among both end portions of the inner side surface in the second direction.

Images