Electricity storage device, electricity storage module, and mobile body

Abstract

The present invention is an electricity storage device having an electrode section, an exterior member covering the electrode section, and a terminal section. The exterior member has a housing section that houses the electrode section, and a sealing strip section which is connected to the outer edge of the housing section and in which a first packaging material and a second packaging material are directly or indirectly bonded. The sealing strip section has: a first sealing section in which the first packaging material and the second packaging material are bonded to the electrode section; a second sealing section in which the first packaging material and the second packaging material are directly bonded; and a fastening section that applies bonding force to the first packaging material and the second packaging material. A weak sealing section is formed having a bonding force that is weaker than other portions of the sealing strip section.

Description

Power storage device, power storage module, and moving body

[0001] The present invention relates to a power storage device, a power storage module including the power storage device, and a moving body including the power storage module.

[0002] A conventional power storage device is disclosed in Patent Document 1. In this power storage device, a power storage element is enclosed in an exterior member. The power storage element has a configuration in which a positive electrode plate and a negative electrode plate are arranged to face each other via a separator, and an electrolyte is disposed between the positive electrode plate and the negative electrode plate. The power storage device has a configuration in which the power storage element is housed inside an exterior material formed of a resin film including a metal layer or a barrier layer. By covering the power storage element and the electrolyte with the resin film and sealing the outer edge portion, the power storage element is sealed by the exterior material.

[0003] In addition, a plurality of power storage devices having such a configuration are arranged side by side, and the power storage devices are connected in parallel or in series, and a power storage module housed in a module, a pack, or directly in a moving body is also used.

[0004] Japanese Patent No. 3852110

[0005] In recent years, the power storage capacity of power storage devices has been increasing. Along with the increase in the power storage capacity, the internal pressure acting on the exterior material tends to increase due to gas generation, particularly during rapid charging, of the power storage element. In addition, thermal runaway may occur in battery failures such as internal short circuits. When thermal runaway occurs, the battery temperature rises rapidly, and there is also a possibility of smoke generation and ignition.

[0006] An object of the present invention is to provide a power storage module that repeatedly performs rapid charging, and when the internal pressure and temperature rise and exceed a certain level, releases internal gas to the outside from a predetermined position to suppress smoke generation and ignition.

[0007] An exemplary energy storage device of the present invention comprises: a long electrode portion in which positive electrode plates and negative electrode plates are alternately stacked via an intermediate member; an outer casing member having a first packaging material and a second packaging material that cover the electrode portion from both outer sides in the stacking direction of the electrode portion; and terminal portions electrically connected to the positive electrode plate and the negative electrode plate, respectively. The outer casing member has a housing portion for housing the electrode portion and a sealing band portion connected to at least a part of the outer edge of the housing portion to seal the housing portion by directly or indirectly joining the first packaging material and the second packaging material. The sealing band portion has a fastening portion that applies a fastening force in the stacking direction to the first packaging material and the second packaging material by a fastening member that penetrates and fastens the first packaging material and the second packaging material, and a weak sealing portion in which the joining strength between the first packaging material and the second packaging material is weaker than that of other parts of the sealing band portion.

[0008] According to the present invention, by repeatedly performing rapid charging, the internal pressure and temperature rise, and when they exceed a certain level, the internal gas is released to the outside from a predetermined position, thereby suppressing smoke and fire.

[0009] Figure 1 is a front view of the energy storage device 1. Figure 2 is a cross-sectional view of the energy storage device shown in Figure 1, taken along line II-II. Figure 3 is an enlarged cross-sectional view of the energy storage device shown in Figure 1, taken along line III-III. Figure 4 is a cross-sectional view showing the laminated structure of the resin sheets. Figure 5 is an exploded perspective view of the energy storage device. Figure 6 is a perspective view of the energy storage module. Figure 7 is a cross-sectional view of the energy storage module shown in Figure 6, taken across plane VII. Figure 8 is a side view of the electric vehicle. Figure 9 is a top view of the electric vehicle. Figure 10 is an enlarged view of the weakly sealed portion of the energy storage device of the first modified example. Figure 11 is a front view of the energy storage device of the second modified example. Figure 12 is a front view of the energy storage device of the third modified example. Figure 13 is an enlarged front view of the energy storage device of the fourth modified example. Figure 14 is a cross-sectional view of the energy storage device shown in Figure 13, taken along line XIV-XIV. Figure 15 is a top view of the terminal portion. Figure 16 is an enlarged cross-sectional view of the fastening portion of the energy storage device of the fifth modified example.

[0010] The following describes an energy storage device according to one embodiment of the present invention with reference to the drawings. However, the scope of the present invention is not limited to the following embodiments and can be arbitrarily modified within the scope of the technical concept of the present invention.

[0011] In this specification, the energy storage device 1 is defined as having the vertical direction as the Y direction, the horizontal direction as the X direction, and the thickness direction as the Z direction, based on the state shown in Figures 1 and 2. In the energy storage device 1, the Z direction is the front-to-back direction. Each direction is assigned for convenience to facilitate explanation and does not indicate the direction during actual use.

[0012] <Energy Storage Device 1> Figure 1 is a front view of energy storage device 1. Figure 2 is a cross-sectional view of energy storage device 1 shown in Figure 1, cut along line II-II. Figure 3 is an enlarged cross-sectional view of energy storage device 1 shown in Figure 1, cut along line III-III.

[0013] As shown in Figure 1, in a front view, the energy storage device 1 is rectangular in shape with the X direction as its longitudinal direction. As shown in Figures 1, 2, and 3, the energy storage device 1 includes an outer casing member 10, an energy storage element 20, and a terminal portion 30. The energy storage device 1 has a configuration in which the energy storage element 20 is housed in a housing portion 11 provided in the outer casing member 10, such as a primary battery, secondary battery, or electric double-layer capacitor (including EDLC). Examples of the energy storage device 1 include lithium-ion batteries, lithium-ion polymer batteries, lithium-ion all-solid-state batteries, lithium-ion capacitors, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver-zinc oxide batteries, metal-air batteries, and polyvalent cation batteries.

[0014] <Energy Storage Element 20> As shown in Figure 2, in the energy storage device 1, the energy storage element 20 is housed in the housing section 11 together with the electrolyte. The energy storage element 20 has a positive electrode plate 21, a negative electrode plate 22, and a separator 23. In the energy storage element 20, the positive electrode plate 21 and the negative electrode plate 22 are formed by arranging them opposite each other with an insulating separator 23 in between. In the energy storage device 1, the energy storage element 20 is formed by stacking multiple layers of sheet-like positive electrode plate 21, separator 23, negative electrode plate 22, and separator 23 in the Z direction. In the energy storage device 1, the positive electrode plate 21 and the negative electrode plate 22 are housed in the housing section 11 together with the electrolyte in such a way that the direction in which they are stacked is the Z direction of the energy storage device 1.

[0015] In this embodiment, a liquid electrolyte is used as the electrolyte, and it is filled inside the containment section 11. A solid electrolyte or a gel-like electrolyte may also be used as the electrolyte. The separator 23 is an example of an intermediate member placed between the positive electrode plate 21 and the negative electrode plate 22. When a solid electrolyte is used as the electrolyte, the solid electrolyte is the intermediate member, and there is no separator.

[0016] <Terminal section 30> The terminal section 30 has a positive terminal 31 and a negative terminal 32. The positive terminal 31 is connected to the positive plate 21, and the negative terminal 32 is connected to the negative plate 22. The positive terminal 31 and the negative terminal 32 are electrically conductive. As shown in Figures 1 and 2, the positive terminal 31 and the negative terminal 32 pass through the first sealing portion 121 of the sealing band 12 and protrude to the outside of the exterior member 10. In the energy storage device 1, the positive terminal 31 and the negative terminal 32 are input / output terminals for charging and discharging the energy storage element 20. In a front view, in the energy storage device 1, the positive terminal 31 and the negative terminal 32 protrude outward from both ends in the X direction.

[0017] <Exterior Member 10> The first packaging material 141 and the second packaging material 142 of the exterior member 10 are composed of a resin sheet 40 having at least one insulating layer. Figure 4 is a cross-sectional view showing the laminated structure of the resin sheet 40. As shown in Figure 4, the resin sheet 40 is formed by sequentially laminating at least a base layer 41, a barrier layer 42, and a heat-adhesive resin layer 43. The thickness of the resin sheet 40 is preferably 50 μm or more considering the strength of the exterior member 10, and preferably 400 μm or less considering the weight reduction of the energy storage device 1. The thicker the barrier layer 42, the higher the strength and thermal conductivity. Therefore, if strength and thermal conductivity of the exterior member 10 are required even if the weight of the energy storage device 1 increases, the thickness of the resin sheet 40 may be 1 mm to 2 mm or more.

[0018] The base layer 41 is insulating and is formed from a resin film such as nylon, polyester, or polyethylene terephthalate. The thickness of the base layer 41 is, for example, 10 μm to 75 μm. To improve heat resistance, it is more desirable to form the base layer 41 from a uniaxially oriented film or a biaxially oriented film. The thicker the base layer 41, the less favorable the thermal conductivity in the Z direction becomes. For example, if sufficient thermal conductivity can be ensured by the barrier layer 42, the thickness of the base layer 41 may be about 50 μm.

[0019] Furthermore, to improve pinhole resistance, insulation, etc., multiple resin films of different materials may be laminated to form the base layer 41. In this case, the multiple resin films are bonded together with a polyurethane-based, acrylic-based, silicone-based adhesive or an acid-modified resin. In this embodiment, the resin sheet 40 is formed by laminating polyethylene terephthalate (thickness 12 μm) and nylon (thickness 15 μm) with an adhesive (thickness 4 μm).

[0020] The barrier layer 42 prevents the intrusion of water vapor, oxygen, light, etc. As the barrier layer 42, for example, metal foil such as aluminum, aluminum alloy, stainless steel, titanium, iron, or high-strength steel can be used. The thickness of the barrier layer 42 is formed to be, for example, 10 μm or more and 500 μm or less. The base layer 41 and the barrier layer 42 are bonded together with an adhesive such as polyurethane, acrylic, or silicone, or an acid-modified resin (not shown). In the resin sheet 40 of this embodiment, the barrier layer 42 is formed of aluminum foil with a thickness of 40 μm.

[0021] The heat-adhesive resin layer 43 can be any resin that has heat-adhesive properties, and is formed from, for example, a heat-adhesive resin such as polypropylene, acid-modified polypropylene, low-density polyethylene, or linear low-density polyethylene. Multiple layers of resins of different materials may be laminated to form the heat-adhesive resin layer 43. The thickness of the heat-adhesive resin layer 43 is formed to be, for example, 10 μm or more and 100 μm or less. The heat-adhesive resin layer 43 is formed by extrusion onto the barrier layer 42. The film forming the heat-adhesive resin layer 43 may be bonded to the barrier layer 42 via an adhesive. Depending on the size of the energy storage element 20 housed in the housing 11, and the weight of the energy storage element 20 and the electrolyte, the thickness of the heat-adhesive resin layer 43 may be 100 μm or more and 500 μm or less.

[0022] In the resin sheet 40 of this embodiment, the heat-adhesive resin layer 43 is formed by sequentially extruding acid-modified polypropylene (thickness 40 μm) and polypropylene (thickness 40 μm) onto the barrier layer 42. In the second sealing portion 122 of the sealing band portion 12, the heat-adhesive resin layer 43 of the first packaging material 141 and the heat-adhesive resin layer 43 of the second packaging material 142 are brought into contact with each other and bonded by heat sealing through heating and pressurization.

[0023] Figure 5 is an exploded perspective view of the energy storage device 1. The exterior member 10 is formed integrally from a first packaging material 141 and a second packaging material 142 in a continuous manner in the Y direction. The first packaging material 141 has a housing portion 11 and a flange portion 15. The first packaging material 141 and the second packaging material 142 are made of resin sheets. The first packaging material 141 is formed, for example, by cold forming to create a housing portion 11 recessed to a predetermined depth relative to the flange portion 15. The housing portion 11 has a substantially rectangular opening 11a on one side to house the energy storage element 20. The flange portion 15 is formed to protrude outward from one of the short and long sides of the opening 11a. The second packaging material 142 is formed in the shape of a rectangular sheet. A sealing band portion 12 is formed by, for example, heat bonding the second packaging material 142 to the flange portion 15. The second packaging material 142 also forms a lid portion 16 that covers the opening 11a.

[0024] <Sealing Band 12> Next, the details of the sealing band 12 will be described. The sealing band 12 has two first sealing parts 121, a second sealing part 122, and a fastening part 123. In a front view, the sealing band 12 is strip-shaped and configured to connect to one of the long sides and both of the short sides of the housing part 11. In the sealing band 12, the first packaging material 141 and the second packaging material 142 are in close contact. Here, close contact means that gases released from the electrolyte sealed in the housing part 11, and gases generated by rapid charging, etc., do not leak to the outside, and that contact is made while blocking water vapor from the outside.

[0025] In the sealing band portion 12, the first sealing portion 121 is the portion that overlaps with the positive terminal 31 or the negative terminal 32 in the front and back directions. The second sealing portion 122 is the portion of the sealing band portion 12 other than the first sealing portion 121.

[0026] In other words, in a front view, the portion of the sealing band 12 that connects to both short sides of the housing 11 and overlaps with the positive terminal 31 or negative terminal 32 in the front and rear directions is the first sealing portion 121. The entire portion of the sealing band 12 that connects to one of the long sides of the housing 11, and the portion of the short side other than the first sealing portion 121, constitutes the second sealing portion 122.

[0027] In the first sealing portion 121, the positive terminal 31 and negative terminal 32 of the terminal portion 30 are sandwiched between the flange portion 15 and the lid portion 16 via a heat-adhesive tab film 50. In this state, the flange portion 15 and the lid portion 16 are heated and pressurized. As a result, the first packaging material 141 and the second packaging material 142 are indirectly melted and bonded together. Consequently, the sealing performance around the first sealing portion 121 is improved.

[0028] As a result, in the first sealing portion 121, the first packaging material 141 and the second packaging material 142 are in close contact with the positive terminal 31 and the negative terminal 32 of the terminal portion 30.

[0029] Furthermore, in the second sealing section 122, the heat-adhesive resin layers 43 of the first packaging material 141 and the second packaging material 142 are in direct contact. In this state, the first packaging material 141 and the second packaging material 142 are heat-bonded by heating and pressurizing them. In other words, in the second sealing section 122, the first packaging material 141 and the second packaging material 142 are directly melted and bonded together.

[0030] In addition, the portion of the second sealing portion 122 adjacent to the long side of the housing portion 11 may be referred to as the long side portion 1221, and the portion adjacent to the short side of the housing portion 11 may be referred to as the short side portion 1222.

[0031] Furthermore, in the sealing band portion 12, the fastening portion 123 is formed in the second sealing portion 122. The fastening portion 123 is formed by sewing the first packaging material 141 and the second packaging material 142 together with a wire 124 having a higher heat resistance temperature than the resin sheet 40. The wire 124 is an example of a fastening member. Examples of the wire 124 include fine stainless steel wire, fine tungsten wire, and fine aramid fiber wire. However, it is not limited to these, and a wide range of wires with a higher heat resistance temperature than the resin sheet 40, or flame-retardant wires, can be used as the wire 124. The fastening portion 123 is not formed in the weak sealing portion 13, which will be described later. Also, as shown in Figure 1, the fastening portion 123 sews the first packaging material 141 and the second packaging material 142 together, including the tab film 50, but it is not limited to this. For example, the tab film 50 may not be fastened at the fastening portion 123.

[0032] When the energy storage device 1 is repeatedly charged and discharged, especially when rapidly charged, the electrolyte contained in the storage section 11 becomes hot, which accelerates decomposition and generates gas. Due to the generation of gas, the pressure inside the storage section 11 increases, and a force acts on the sealing band 12 that separates the first packaging material 141 and the second packaging material 142. The force that separates the first packaging material 141 and the second packaging material 142 is a force corresponding to the amount and speed of gas generation, or the expansion and contraction force due to the charging and discharging of the battery itself. Due to the shape characteristics of the sealing band 12, the force that separates the first packaging material 141 and the second packaging material 142 tends to concentrate in the center of the X direction of the portion adjacent to the long side of the storage section 11. Because the fastening portion 123 is formed, the fastening force of the fastening portion 123 counteracts the force that separates the first packaging material 141 and the second packaging material 142 on the second sealing portion 122, making separation less likely to occur.

[0033] Furthermore, as shown in Figures 1, 2, and 3, the width of the sealing band portion 12 from the inside to the outside of the first sealing portion 121 is defined as width W1, and the width of the sealing portion 122 from the inside to the outside is defined as width W2. In this case, width W1 is greater than width W2. That is, the width W1 of the first sealing portion 121 is wider than the width W2 of the second sealing portion 122. As a result, the fastening strength of the first sealing portion 121 is higher than that of the second sealing portion 122. Therefore, even if a force that causes separation of the first packaging material 141 and the second packaging material 142 is applied to the first sealing portion 121, separation is less likely to occur at the first sealing portion 121. Note that even if the width W1 is narrow and the fastening strength is weak, an auxiliary mechanism can be provided on the outside.

[0034] As described above, in the exterior member 10 of the energy storage device 1, the first sealing portion 121 increases the width W1 to expand the area that is heat-bonded, thereby increasing the fastening strength and suppressing the peeling of the first packaging material 141 and the second packaging material 142. In addition, the second sealing portion 122 resists the force of the fastening portion 123 that would cause the first packaging material 141 and the second packaging material 142 to peel apart, thereby suppressing the peeling of the first packaging material 141 and the second packaging material 142.

[0035] Due to the shape characteristics of the sealing band portion 12, the force that separates the first packaging material 141 and the second packaging material 142 tends to concentrate in the center of the portion adjacent to the long side of the housing portion 11 in the X direction. In other words, the force that separates the first packaging material 141 and the second packaging material 142 is concentrated in the center of the long side portion 1221 of the second sealing portion 122.

[0036] In the energy storage device 1, a weak sealing portion 13 is formed in the central part of the long side portion 1221 in the X direction of the second sealing portion 122. As shown in Figure 1, a fastening portion 123 is not formed in the weak sealing portion 13. The bonding force in the weak sealing portion 13 with this configuration is smaller than the bonding force in the other parts of the first sealing portion 121 and the second sealing portion 122.

[0037] When the internal pressure of the housing section 11 of the energy storage device 1 rises, the weakly sealed section 13 in the sealing band 12 separates the first packaging material 141 and the second packaging material 142 before the other parts. In other words, the weakly sealed section 13 is opened at a lower internal pressure than the other parts. As a result, a leak section is formed in the weakly sealed section 13 to release gas from inside the housing section 11. The formation of the leak section allows the gas and electrolyte generated inside the housing section 11 to be discharged to the outside. In other words, in the energy storage device 1, when the internal pressure of the housing section 11 reaches a certain pressure due to the gas generated by repeated rapid charging, the gas can be discharged to the outside. Furthermore, by providing a weakly sealed section 13 with a lower sealing force than the other parts, the gas can be discharged from a predetermined position.

[0038] In the energy storage device 1, smoke and fire occur when three conditions coincide: (1) gas generation due to accelerated decomposition of the electrolyte as it becomes hot, (2) spark generation between the positive electrode plate 21 and the negative electrode plate 22, and (3) oxygen generation from the positive electrode plate 21. In other words, smoke and fire can be suppressed by preventing the three conditions from coinciding. Therefore, in the energy storage device 1 of this embodiment, when the internal pressure and temperature of the storage section 11 exceed a certain level, the weakly sealed section 13 is opened before the three conditions described above coincide, and the gas inside the storage section 11 is discharged to the outside. This suppresses smoke and fire from the energy storage device 1.

[0039] Furthermore, when the gas inside the housing section 11 of the exterior member 10 is discharged, the electrolyte is also discharged along with the gas. When the electrolyte is discharged, the chemical reaction between the positive electrode plate 21 and the negative electrode plate 22 is suppressed, the voltage between the positive electrode plate 21 and the negative electrode plate 22 decreases, and sparks between the positive electrode plate 21 and the negative electrode plate 22 are suppressed. From this, it can be seen that by discharging the gas accumulated inside the housing section 11 at an early stage, smoke and fire of the energy storage device 1 can be suppressed.

[0040] As described above, the force that separates the first packaging material 141 and the second packaging material 142 is concentrated in the central part of the long side portion 1221 of the housing portion 11 of the second sealing portion 122, so a weak sealing portion 13 is formed in the central part of the long side portion 1221. On the other hand, depending on the shape and mounting state of the energy storage device 1, the force may be concentrated in other locations. In such a configuration, a weak sealing portion 13 may be provided in a part of the long side portion 1221 of the second sealing portion 122 other than the central part. In this case, the weak sealing portion 13 in the central part of the long side portion 1221 may be eliminated and a weak sealing portion 13 may be formed in another location, or the weak sealing portion 13 in the central part may be left and a weak sealing portion 13 may be added to a new part.

[0041] Furthermore, in the energy storage module 100 described later, the gas discharge location may be predetermined. In such cases, the weakly sealing portion 13 may be formed at a location that allows gas to be discharged to the required gas discharge location of the second sealing portion 122.

[0042] By configuring the device in this way, repeated rapid charging in the energy storage device 1 causes the electrolyte to decompose and generate gas. When the internal pressure rises to a certain value, the gas can be released to the outside before the three conditions for ignition described above coincide, thus suppressing smoke and fire.

[0043] As the exterior member 10 of the power storage device 1 described above, a so-called single cup type container in which a storage portion 11 recessed in the first packaging material 141 is formed is adopted, but it is not limited thereto. For example, the exterior member 10 may be a double cup type container configured to form recesses in both the first packaging material 141 and the second packaging material 142 and abut the openings. Further, it may be a four-sided seal type container in which a lid portion 16 made of the second packaging material 142 is sealed to a flange portion 15 that extends outward from the four sides of the opening portion 11a of the storage portion 11. Furthermore, the first packaging material 141 and the second packaging material 142 may be formed from separate sheets respectively.

[0044] In the power storage device 1 of the present embodiment, one of the long sides of the rectangular shape in plan view is the folded-back portion of the first packaging material 141 and the second packaging material 142, the positive electrode terminal 31 is arranged on one short side, and the negative electrode terminal 32 is arranged on the other short side, and a weak seal portion 13 is formed in the seal band portion 12 provided on the long side. However, it is not limited to this configuration. For example, a configuration in which the positive electrode terminal 31 and the negative electrode terminal 32 are arranged on one short side may be adopted. Further, for example, a weak seal portion 13 having the same configuration as the weak seal portion 13 may be formed in the seal band portion 12 provided on at least one of the short sides. At this time, the weak seal portion 13 formed in the seal band portion 12 provided on the long side may be formed or may be omitted.

[0045] Further, at least one of the positive electrode terminal 31 and the negative electrode terminal 32 may be arranged on the long side opposite to the folded-back portion of the first packaging material 141 and the second packaging material 142, or both may be arranged. At this time, at least one weak seal portion 13 may be formed in the seal band portion 12 provided on at least one of the short sides, or at least one weak seal portion 13 may be formed in the seal band portion 12 provided on the long side.

[0046] Also, when the power storage device is of the four-side seal type, the positive electrode terminal 31 may be arranged in the sealing strip portion 12 provided on the short side, or may be arranged in the sealing strip portion 12 provided on the long side. Also, the negative electrode terminal 32 may be arranged in the sealing strip portion 12 provided on the short side, or may be arranged in the sealing strip portion 12 provided on the long side. In this case, at least one weak sealing portion 13 may be formed in the sealing strip portion 12 provided on at least one of the long sides, and at least one weak sealing portion 13 may be formed in the sealing strip portion 12 provided on at least one of the short sides.

[0047] <Power storage module 100> The details of the power storage module 100 will be described below with reference to the drawings. FIG. 6 is a perspective view of the power storage module 100. FIG. 7 is a cross-sectional view taken along the VII plane of the power storage module 100 shown in FIG. 6. The power storage module 100 is configured by housing a plurality of power storage devices 1 in a case 200. In the power storage module 100 shown in FIG. 6, for ease of understanding, a part of the body portion 201 is not shown.

[0048] As shown in FIG. 6, in the power storage module 100, ten power storage devices 1 are arranged inside the case 200, but the actual number of arranged devices is not limited to ten. The number and connection method of the power storage devices 1 arranged in the power storage module 100 may be changed according to the required capacitance, output voltage, etc. When the power storage devices 1 are connected in parallel, the positive electrode terminals 31 and the negative electrode terminals 32 of adjacent power storage devices 1 are arranged adjacent to each other. Also, when the power storage devices are connected in series, the positive electrode terminal 31 and the negative electrode terminal 32 of adjacent power storage devices 1 are arranged in the case 200 adjacent to each other. Note that the power storage device 1 has a configuration in which the long side portions 1221 of the second sealing portions 122 of the sealing strip portions 12 are gathered with the long side portions 1221 arranged downward (see FIG. 7).

[0049] The case 200 has a body portion 201 and a closing portion 202. The body portion 201 is formed in a cylindrical shape with both ends in the axial direction open. The closing portion 202 closes both ends in the axial direction of the body portion 201. By attaching the closing portion 202 to the body portion 201, the case 200 is sealed so that moisture from the outside does not penetrate.

[0050] The case 200 is formed from an insulator such as resin. In addition, metals such as aluminum alloy or stainless steel may be used to increase the strength of the case 200. In this case, the inner surface that comes into contact with the energy storage device 1 and the parts that the electrode terminals may come into contact with are insulated.

[0051] Furthermore, the positive terminal 31 and negative terminal 32 of each energy storage device 1 are connected to a busbar (not shown). Lead terminals (not shown) are connected to the busbar, and these lead terminals are brought out to the outside of the case 200. The lead terminals are external connection terminals that are connected to external equipment such as charging devices and loads.

[0052] The case 200 may also be equipped with an auxiliary mechanism (not shown) to increase the fastening strength of the first sealing portion 121, or a retaining member (not shown) to suppress the movement of the energy storage device 1 inside the case 200.

[0053] As shown in Figure 7, the bottom plate portion 203 of the case 200 has a plurality of slits 204 formed therein. The number of slits 204 is the same as the number of energy storage devices 1. When the energy storage devices 1 are attached to the case 200, the long side portion 1221 of the second sealing portion 122 of the sealing band portion 12 of the energy storage device 1 is inserted into the slits 204.

[0054] The slit 204 penetrates the bottom plate portion 203 in the thickness direction. Therefore, in the energy storage device 1, when the internal pressure of the housing portion 11 rises, the weak seal portion 13 opens, and gas is discharged from the weak seal portion 13, the gas can be discharged to the outside of the case 200. By configuring the case 200 to discharge flammable gas to the outside in this way, smoke and fire from the energy storage device inside the case 200 can be suppressed.

[0055] <Electric Vehicle 300> Figure 8 is a side view of the electric vehicle 300. Figure 9 is a top view of the electric vehicle 300. The electric vehicle 300 is equipped with a drive motor 302 as a power source to drive the wheels 301. A power storage pack 400 is installed under the floor of the vehicle body (mobile body) of the electric vehicle 300 as a power source to supply power to the drive motor 302.

[0056] The energy storage pack 400 has a configuration in which multiple energy storage modules 100 are arranged in a row on an exterior component such as a frame (not shown). By connecting the energy storage modules 100 arranged on the exterior component such as the frame in series and in parallel, the energy storage pack 400 can obtain the required energy storage capacity and output the required output voltage.

[0057] As shown in Figure 9, in the energy storage pack 400, the energy storage modules 100 are arranged such that the Y direction is the height direction (gravity direction) of the electric vehicle 300, the Z direction is the front-to-back direction of the electric vehicle 300, and the X direction is the left-to-right direction of the electric vehicle 300. In other words, in the energy storage pack 400, energy storage modules 100 with the Y direction as the height direction are arranged in the X and Z directions.

[0058] The energy storage module 100 is positioned so that the slit 204 opens to the outside from the underside of the electric vehicle 300. This arrangement allows the gas discharged from the weakly sealed portion 13 of the energy storage device 1 to be discharged to the outside of the electric vehicle 300. This suppresses smoke and fire from the electric vehicle 300. The slit 204 does not need to be directly exposed to the outside, as long as the gas discharged from the slit 204 can be discharged to the outside of the electric vehicle 300.

[0059] Furthermore, if the electric vehicle 300 is a low-profile sedan or compact car, the energy storage pack 400 is configured as a single-stage energy storage module 100 in the height direction. If the electric vehicle 300 is a tall SUV or minivan, the energy storage module 100 is configured as a multi-stage energy storage module in the height direction of the vehicle. In this way, it is possible to provide an energy storage pack 400 with an output voltage and energy storage capacity appropriate to the weight and size of the vehicle.

[0060] Alternatively, the electric vehicle 300 may be positioned such that the X-direction, which intersects the Z-direction in which the energy storage devices 1 in the energy storage module 100 are arranged, is the direction of travel. In this way, even when the energy storage module 100 is positioned on the electric vehicle 300, the same effects as described above can be obtained.

[0061] Alternatively, the energy storage devices 1 may be directly arranged in a row under the floor (chassis) of the electric vehicle 300 to form an energy storage unit with the same output voltage and storage capacity as the energy storage pack 400. By doing so, the exterior components such as the frame of the energy storage pack 400 can be omitted, thus enabling weight reduction. When the underfloor (chassis) of the electric vehicle 300 is configured in this way, the case 200 can also be omitted, further enabling weight reduction.

[0062] Furthermore, the portion that releases gas to the outside (in this case, the slit 204) is not limited to the bottom of the electric vehicle 300, but may be determined according to the placement of the energy storage module 100 in the electric vehicle 300.

[0063] In addition to BEVs (Battery Electric Vehicles) and PHEVs (Plug-in Hybrid Electric Vehicles), other examples of mobile vehicles equipped with the aforementioned energy storage pack 400 include HEVs (Hybrid Electric Vehicles) and 48V power supply micro-hybrid vehicles.

[0064] Furthermore, the aforementioned energy storage module or energy storage pack may be mounted on other mobile devices. Examples of mobile devices that can be equipped with the energy storage module or energy storage pack include bipedal robots, trains, airplanes, helicopters, drones, flying cars, agricultural machinery, construction machinery, etc. If the required output voltage and energy storage capacity are sufficient, the energy storage module 100 may be used as a standalone unit.

[0065] Furthermore, the energy storage module or energy storage pack may be used for purposes other than as a power source for mobile devices. For example, it may be used as a fixed power source for an Energy Storage System, a Battery Energy Storage System, or an Uninterruptible Power Supply.

[0066] <First Modification> As shown in Figure 10, fastening portions 123 may also be formed in the weakly sealed portion 131. In this case, if the fastening portion 123 in the second sealed portion 122 is formed with a pitch P1, then the fastening portion 123 in the weakly sealed portion 131 is formed with a pitch P2. Pitch P2 is larger than pitch P1. With this configuration, the bonding force between the first packaging material 141 and the second packaging material 142 in the weakly sealed portion 131 is lower than in other parts of the second sealed portion 122. With this configuration, the weakly sealed portion 131 is easily peeled off, and the weakly sealed portion 131 is opened by the increase in internal pressure of the containment portion 11, allowing the internal gas to be discharged before smoke or fire occurs.

[0067] <Second Modification> As shown in Figure 11, the weak sealing portion 132 may also be formed in the first sealing portion 121. In this case, the width W3 of the weak sealing portion 132 extending outward from the housing portion 11 is formed to be narrower than the width W1 of the first sealing portion 121. By forming it in this way, the weak sealing portion 132 will detach when the pressure inside the housing portion 11 exceeds a certain pressure. The gas inside the housing portion 11 will be discharged to the outside from the detached weak sealing portion 132. However, there is a possibility that the gas may ignite due to sparks generated at the electrodes. For this reason, when forming the weak sealing portion 132 in the first sealing portion 121, it is preferable to form it in the first sealing portion 121 where the negative electrode terminal 32 is located. A gas absorption portion made of a gas-absorbing material may be placed outside the weak sealing portion 131. In this case, the weak sealing portion 13 may be omitted.

[0068] <Third Modification> The third modification of the energy storage device 1A will be described with reference to the drawings. Figure 12 is a front view of the third modification of the energy storage device 1A. In the energy storage device 1A shown in Figure 12, the shape of the outer casing member 10A, the energy storage element 20A, and the positive terminal 31A and negative terminal 32A of the terminal portion 30A differ from those of the outer casing member 10, the energy storage element 20, and the positive terminal 31 and negative terminal 32 of the terminal portion 30. Other than these differences, the energy storage device 1A has the same configuration as the energy storage device 1. Therefore, parts of the energy storage device 1A that are substantially the same as those of the energy storage device 1 are given the same reference numerals, and detailed descriptions of these same parts are omitted.

[0069] As shown in Figure 12, in a front view, the housing portion 11 of the exterior member 10A of the energy storage device 1A is rectangular in shape with the Y direction as the longitudinal direction. Two first sealing portions 121 are formed at both ends in the X direction of the portion of the sealing band 12A that connects to one end of the housing portion 11 in the Y direction. A positive terminal 31A is placed on one of the two first sealing portions 121A, and a negative terminal 32A is placed on the other. The portion of the sealing band 12A other than the first sealing portions 121A is the second sealing portion 122A.

[0070] In the energy storage device 1A, the width of the first sealing portion 121A extending from the housing portion 11 to the outside is greater than the width of the other parts of the sealing band portion 12. Therefore, in the first sealing portion 121A, the adhesive strength between the positive terminal 31A or the negative terminal 32A and the first packaging material 141 and the second packaging material 142 is increased. In addition, a weak sealing portion 133 is formed in a part of the second sealing portion 122A. And, a fastening portion 123 is formed in the part of the second sealing portion 122A other than the weak sealing portion 133.

[0071] As a result, when the energy storage device 1A repeatedly charges and discharges and the pressure inside the storage section 11 increases, the first packaging material 141 and the second packaging material 142 are separated at the weak sealing section 133 before smoke or fire occurs, and the gas inside is released.

[0072] Furthermore, in the modified energy storage device 1A, one of the shorter sides of the rectangular shape in plan view is the folded portion between the first packaging material 141 and the second packaging material 142, a positive terminal 31A and a negative terminal 32A are arranged on one of the shorter sides, and a weak sealing portion 13 is formed on the sealing band portion 12 provided on one of the longer sides. However, the configuration is not limited to this. For example, at least one of the positive terminal 31A and the negative terminal 32A may be arranged on the longer side, or both may be arranged. In this case, the positive terminal 31A may be arranged on one of the longer sides and the negative terminal 32A may be arranged on the other longer side, or both the positive terminal 32A and the negative terminal 32A may be arranged on one of the longer sides.

[0073] In this case, at least one weak sealing portion 133 may be formed on the sealing band portion 12 provided on one long side, or at least one may be formed on each of the sealing band portions 12 provided on both long sides. Alternatively, at least one weak sealing portion 133 may be formed on the sealing band portion 12 provided on the short side, and at least one weak sealing portion 133 may be formed on one long side. Furthermore, at least one weak sealing portion 133 may be formed on the sealing band portion 12 provided on the short side, and at least one weak sealing portion 133 may be formed on each of the long sides.

[0074] <Fourth Modification> Another example of the energy storage device will be described with reference to the drawings. Figure 13 is an enlarged front view of the energy storage device 1B of the fourth modification. Figure 14 is a cross-sectional view of the energy storage device 1B shown in Figure 13, taken along the line XIV-XIV. Figure 13 shows an enlarged view of the vicinity where the positive terminal 31B of the terminal portion 30B of the energy storage device 1B is located. In the energy storage device 1B, the shape of the positive terminal 31B of the outer casing member 10B is different from that of the positive terminal 31, and the configuration of the fastening portion 125 of the sealing band portion 12B is different from that of the fastening portion 123 of the sealing band portion 12. In all other respects, the energy storage device 1B has the same configuration as the energy storage device 1. The same reference numerals are used for the same parts of the energy storage device 1B as for the energy storage device 1, and detailed descriptions of the same parts are omitted. The negative terminal, which is not shown, has a similar configuration.

[0075] As shown in Figures 13 and 14, in the energy storage device 1B, the positive electrode terminal 31B has a plurality of through holes 311 that penetrate in the Z direction. The through holes 311 are arranged in the Y direction. In the first sealing portion 121B of the energy storage device 1B, the wire 124 of the fastening portion 125 penetrates the first packaging material 141, the through holes 311, and the second packaging material 142. To explain further, the wire 124 is inserted through the through holes 311, and in the first sealing portion 121B, the first packaging material 141 and the second packaging material 142 are sewn to the positive electrode terminal 31B to form the fastening portion 125.

[0076] This configuration suppresses the separation of the first packaging material 141 and the second packaging material 142 in the first sealing portion 121. In the energy storage device 1B, the fastening portion 125 is formed along the entire length of the sealing band portion 12B. This configuration allows the entire fastening portion 125 to be formed from a single wire, making it difficult to form weaker parts than other parts of the fastening portion 125. This increases the fastening force provided by the fastening portion 125. The fastening portion 125 may also be partially discontinuous. For example, the fastening portion 125 may be formed by dividing it into portions located at both ends in the X direction of the sealing band portion 12B and a portion located at one end in the Y direction.

[0077] As shown in Figure 15, the portion where the fastening portion 125 of the positive terminal 31B is formed may be a mesh-like mesh portion 312. With this configuration, the fastening portion 125 can be formed on the first sealing portion 121B using a sewing machine or the like. This makes it easy to form the fastening portion 125 on the first sealing portion 121B. The ratio of the opening area of ​​the mesh portion 312 is preferably such that the positive terminal 31B has a certain level of rigidity while being easy to sew with the wire 124. The negative terminal may have a similar configuration.

[0078] <Fifth Modification> Further examples of the energy storage device will be described with reference to the drawings. Figure 16 is an enlarged cross-sectional view of the fastening portion 126 of the fifth modification of the energy storage device 1C. The configuration of the fastening portion 126 in the energy storage device 1C differs from that of the fastening portion 123 of the energy storage device 1. In all other respects, the energy storage device 1C has the same configuration as the energy storage device 1. The same reference numerals are used for the same parts of the energy storage device 1C as in the energy storage device 1, and detailed descriptions of the same parts are omitted.

[0079] As shown in Figure 16, the fastening portion 126 of the energy storage device 1C uses staples 127. The first packaging material 141 and the second packaging material 142 are fastened together along the entire length of the second sealing portion 122. Note that the staples 127 are just one example of fastening members. By constructing the fastening portion 126 using staples 127 in this way, it is easier to manufacture compared to a fastening portion constructed by sewing together wires. The material of the staples can be metal or a material equivalent to that of the wire 124.

[0080] It should be noted that the present invention is not limited to the configuration described above, and various modifications are possible. Configurations obtained by appropriately combining the technical means disclosed for each different configuration are also included within the technical scope of the present invention.

[0081] <Summary> The energy storage module of the present invention has the following configuration.

[0082] (1) An energy storage device comprising: an elongated electrode portion in which positive electrode plates and negative electrode plates are alternately stacked via an intermediate member; an outer casing member having a first packaging material and a second packaging material that cover the electrode portion from both outer sides in the stacking direction of the electrode portion; and terminal portions electrically connected to the positive electrode plate and the negative electrode plate, wherein the outer casing member has a housing portion for housing the electrode portion; and a sealing band portion connected to at least a part of the outer edge of the housing portion to directly or indirectly join the first packaging material and the second packaging material to seal the housing portion; the sealing band portion having a fastening portion that applies a fastening force in the stacking direction to the first packaging material and the second packaging material by a fastening member that fastens through the first packaging material and the second packaging material; and a weak sealing portion in which the bonding strength between the first packaging material and the second packaging material is weaker than that of other parts of the sealing band portion.

[0083] (2) The fastening portion is formed in a portion other than the weak sealing portion, as described in (1).

[0084] (3) The energy storage device according to (1) or (2), wherein the sealing band portion comprises a first sealing portion to which the first packaging material and the second packaging material are adhered to the electrode portion, and a second sealing portion which is a portion different from the first sealing portion to which the first packaging material and the second packaging material are directly adhered.

[0085] (4) The energy storage device according to (3), wherein the weak sealing portion is formed in the longitudinal center of the portion of the electrode portion of the second sealing portion that is along the longitudinal direction.

[0086] (5) The portion of the terminal portion to which the first sealing portion is bonded has a plurality of through holes that penetrate in the stacking direction, and the fastening portion is formed when the fastening member penetrates the through holes, as described in (3) or (4).

[0087] (6) The fastening member is a wire with a higher heat resistance temperature than the outer layer member. The energy storage device according to any one of (1) to (5).

[0088] (7) The fastening member is a staple. The energy storage device according to any one of (1) to (6).

[0089] (8) A power storage module comprising a plurality of power storage devices according to any one of (1) to (7), and a housing case capable of housing the power storage devices arranged in the stacking direction, wherein at least a portion of the weak sealing portion of the sealing band is exposed to the outside of the housing case.

[0090] (9) A mobile body having an energy storage module as described in (8), a drive motor powered by the energy storage device assembly, and a main body on which the energy storage device assembly and the drive motor are arranged, wherein at least the portion of the second sealing portion on which the weak sealing portion is formed communicates with the outside from the lower part of the main body.

[0091] According to the present invention, it can be widely used in mobile bodies equipped with electric devices.

[0092] 100 Energy storage module 200 Case 201 Body 202 Closure 203 Bottom plate 204 Slit 300 Electric vehicle 301 Wheel 302 Drive motor 311 Through hole 312 Mesh part 400 Energy storage pack 1, 1A, 1B, 1C Energy storage device 10, 10A, 10B Exterior member 11 Housing part 11a Opening 12, 12A, 12B Sealing band part 121, 121A, 121B First sealing part 122, 122A Second sealing part 123 Fastening part 1221 Long side part 1222 Short side part 124 Wire 125 Fastening part 126 Fastening part 127 Staple pin 13 Weak sealing part 131 Weak sealing part 132 Weak sealing portion 133 Weak sealing portion 141 First packaging material 142 Second packaging material 15 Flange portion 16 Lid portion 20, 20A Energy storage element 21 Positive electrode plate 22 Negative electrode plate 23 Separator 30, 30A, 30B Terminal portion 31, 31A, 31B Positive electrode terminal 32, 32A, 32A Positive electrode terminal 40 Resin sheet 41 Base material layer 42 Barrier layer 43 Heat-adhesive resin layer 50 Tab film

Claims

1. An energy storage device comprising: a long electrode portion in which positive electrode plates and negative electrode plates are alternately stacked via an intermediate member; an outer casing member having a first packaging material and a second packaging material that cover the electrode portion from both outer sides in the stacking direction of the electrode portion; and terminal portions electrically connected to the positive electrode plate and the negative electrode plate, respectively, wherein the outer casing member has a housing portion for housing the electrode portion; and a sealing band portion connected to at least a part of the outer edge of the housing portion to directly or indirectly join the first packaging material and the second packaging material to seal the housing portion; the sealing band portion has a fastening portion that applies a fastening force in the stacking direction to the first packaging material and the second packaging material by a fastening member that penetrates and fastens the first packaging material and the second packaging material; and a weak sealing portion in which the bonding strength between the first packaging material and the second packaging material is weaker than that of other parts of the sealing band portion.

2. The energy storage device according to claim 1, wherein the fastening portion is formed in a portion other than the weak sealing portion.

3. The energy storage device according to claim 1 or 2, wherein the sealing band portion comprises a first sealing portion to which the first packaging material and the second packaging material are adhered to the electrode portion, and a second sealing portion which is a portion different from the first sealing portion to which the first packaging material and the second packaging material are directly adhered.

4. The energy storage device according to claim 3, wherein the weak sealing portion is formed in the portion of the second sealing portion that is aligned with the longitudinal direction of the electrode portion.

5. The portion of the terminal portion to which the first sealing portion is bonded has a plurality of through holes penetrating in the stacking direction, and the fastening portion is formed when the fastening member penetrates the through holes, as described in claim 3 or claim 4.

6. The energy storage device according to any one of claims 1 to 5, wherein the fastening member is made of wire with a higher heat resistance temperature than the exterior member.

7. The energy storage device according to any one of claims 1 to 6, wherein the fastening member is a staple.

8. A power storage module comprising a plurality of power storage devices according to any one of claims 1 to 7, and a housing case capable of housing the power storage devices arranged in the stacking direction, wherein at least a portion of the weak sealing portion of the sealing band is exposed to the outside of the housing case.

9. A mobile body driven by the drive motor, comprising: a power storage module according to claim 8; a drive motor powered by the power storage module; and a main body on which the power storage module and the drive motor are arranged, wherein at least the portion where the weakly sealed portion is formed communicates with the outside from the lower part of the main body.

Images