Energy storage element

Abstract

This power storage element is provided with: a power generator which is provided with a negative electrode and a positive electrode that comprises an electrode conductor; a first container which contains the power generator; a connection terminal which is electrically connected to an exposed part of the electrode conductor, the exposed part being exposed from the first container; and a first protective member which protects the connection part of the exposed part and the connection terminal. With respect to this power storage element, at least the connection part and a part of the first container are covered by a cover member over a region from the connection part to the part of the first container.

Description

[Technical Field]

[0001] The present disclosure relates to an energy storage element. [Background technology]

[0002] Patent Document 1 discloses an example of a non-electrolyte secondary battery that undergoes repeated charge and discharge cycles. The non-electrolyte secondary battery includes an internal power generator that is composed of a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, and a separator interposed between the positive and negative electrodes. Tab leads are joined to the positive and negative electrodes, respectively. The internal power generator is housed in a film-like exterior body in a sealed state together with a non-aqueous electrolyte solution. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-232666 Summary of the Invention

[0004] An energy storage element according to one embodiment of the present disclosure comprises a power generating body having a positive electrode and a negative electrode with electrode conductors, a first housing that houses the power generating body, a connection terminal electrically connected to an exposed portion of the electrode conductor exposed from the first housing, and a first protective member that protects the connection portion between the exposed portion and the connection terminal, and at least the connection portion and a portion of the first housing are covered by a covering member from the connection portion to a portion of the first housing. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a perspective view showing the appearance of an energy storage element according to the present disclosure. [Figure 2] FIG. 1 is a perspective view showing the appearance of a unit cell according to the present disclosure. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4]FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] 3 is a cross-sectional view showing the specific structures of a positive electrode active material layer and a negative electrode active material layer. FIG. [Figure 6] 2 is a plan view of a first protective member and its periphery in an energy storage device according to the present disclosure. FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6. [Figure 8] FIG. 10 is a plan view showing an energy storage element of a comparative example. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 8. [Figure 10] 10A and 10B are cross-sectional views showing examples of stresses occurring in exposed portions in an energy storage element of a comparative example. [Figure 11] 10A and 10B are cross-sectional views showing examples of stresses occurring in exposed portions in an energy storage element according to the present disclosure. [Figure 12] 1 is a flowchart illustrating an example of a manufacturing process for an energy storage element according to the present disclosure. [Figure 13] 10 is a cross-sectional view showing the configuration of a main part of an energy storage device according to a second embodiment. FIG. [Figure 14] 10 is a plan view showing the configuration of a main part of an energy storage device according to a third embodiment. FIG. [Figure 15] 10 is a plan view showing the configuration of a main part of an energy storage device according to a fourth embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0006] [Embodiment 1] An embodiment of the present disclosure will be described in detail below.

[0007] <Configuration of Energy Storage Element 1> FIG. 1 is a perspective view showing the appearance of an energy storage device 1. The energy storage device 1 is an element that can be charged or discharged by being electrically connected to an external terminal. For example, at least one energy storage device 1 may be mounted in an energy storage device for use in a home, a base station, an automobile, a robot such as a drone, or a medical device. The energy storage device 1 may include a unit cell 10, connection terminals 21 and 22, and a second housing 50. The configuration of the unit cell 10 will be described later.

[0008] The second housing 50 may house the unit cells 10. The second housing 50 may be formed of, for example, an aluminum pouch film or a laminate film having a metal foil layer such as stainless steel or nickel. The aluminum pouch film is a film on which aluminum is vapor-deposited. The film material may be, for example, polypropylene, polyethylene, nylon, or polyethylene terephthalate. The thickness of the second housing 50 may be 50 μm or more and 300 μm or less, for example, 200 μm.

[0009] When the second housing 50 is an aluminum pouch film, the second housing 50 may have a configuration in which two aluminum pouch films are located on both sides in the stacking direction (Z-axis direction) of the unit cell 10. Furthermore, when the second housing 50 is an aluminum pouch film, the second housing 50 may have a configuration in which one aluminum pouch film is folded in half and the unit cell 10 is located inside it.

[0010] The connection terminals 21 and 22 may be terminals to be connected to external terminals in order to extract power from or supply power to the energy storage element 1. The connection terminals 21 and 22 may protrude from the inside to the outside of the second housing 50. The connection terminals 21 and 22 may be made of, for example, copper, aluminum, or nickel. The connection terminals 21 and 22 may have a thickness of 50 μm or more and 500 μm or less, for example, 200 μm. The connection terminals 21 and 22 may also be subjected to a surface treatment to improve adhesion to the adhesive member 40, which will be described later.

[0011] 2 is a perspective view showing the appearance of the unit cell 10. As shown in FIG. 2, the unit cell 10 may include a power generating body 14 and a first housing 15. The power generating body 14 may include a positive electrode 11 and a negative electrode 12.

[0012] The first housing 15 may house the power generator 14. The first housings 15 may be bonded to one another by an adhesive layer (not shown). The material of the first housings 15 may be, for example, PET (polyethylene terephthalate) or nylon. The thickness of the base material may be, for example, 10 μm or more and 40 μm or less, for example, 25 μm. The material of the adhesive layer may be, for example, polypropylene or polyethylene.

[0013] The positive electrode 11 may have an exposed portion 11e exposed from the first housing 15. The negative electrode 12 may have an exposed portion 12e exposed from the first housing 15. The connection terminals 21 and 22 may be electrically connected to the exposed portions 11e and 12e, respectively, by, for example, ultrasonic welding, laser welding, or resistance welding. The positive electrode 11, the negative electrode 12, and the exposed portions 11e and 12e will be described in detail below.

[0014] The energy storage device 1 may have a configuration in which a unit cell 10, in which the positive electrode 11 and the negative electrode 12 are housed in a first housing 15, is further housed in a second housing 50. With this configuration, the power generation body 14 is housed doubly, thereby improving the safety of the energy storage device 1. The second housing 50 may also be housed in a further housing. However, the energy storage device 1 only needs to include the positive electrode 11 and the negative electrode 12, and only needs to be housed in at least one housing.

[0015] In the first embodiment, the energy storage device 1 includes a plurality of unit cells 10, for example, ten layers. However, the energy storage device 1 according to the present disclosure may include a plurality of layers of unit cells 10 other than ten layers, or may include only one layer. When the energy storage device 1 includes a plurality of unit cells 10, the unit cells 10 may be stacked. When the energy storage device 1 shown in FIG. 1 is viewed from above, the portion excluding the connection terminals 21 and 22 may be substantially rectangular or may have a different shape. When the unit cell 10 shown in FIG. 2 is viewed from above, the portion excluding the exposed portions 11e and 12e may be substantially rectangular or may have a different shape.

[0016] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 1. For simplicity, the second container 50 is omitted from FIGS. 3 and 4. Also, FIGS. 3 and 4 mainly show the positional relationship of each component. Therefore, the thickness relationships of each component are not necessarily the same as those in FIGS. 3 and 4. FIGS. 7 and 9, which will be described later, also mainly show the positional relationship of each component, and the thickness relationships of each component are not necessarily the same as those in FIGS. 7 and 9.

[0017] As shown in FIGS. 3 and 4, the energy storage device 1 may further include a first protective member 30. The material of the first protective member 30 may be, for example, polyolefin or polyimide. The first protective member 30 may be adhered to the exposed portions 11e and 12e by an adhesive layer (not shown). The material of the adhesive layer of the first protective member 30 may be any material that is not easily dissolved in the electrolyte solution. The material of the adhesive layer may be, for example, an acrylic adhesive.

[0018] The thickness of first protective member 30 may be equal to or greater than the sum of the thickness of first housing 15 and the thickness of electrode conductors 11a and 12a. For example, if first housing 15 is 25 μm thick, electrode conductor 11a is 10 μm thick, and electrode conductor 12a is 10 μm thick, the thickness of first protective member 30 may be 50 μm or greater. From the viewpoint of productivity, the thickness of first protective member 30 may be 100 μm or less.

[0019] 3 and 4, the positive electrode 11 may have an electrode conductor 11a and a positive electrode active material layer 11b, and the negative electrode 12 may have an electrode conductor 12a and a negative electrode active material layer 12b.

[0020] The electrode conductor 11a may be, for example, an aluminum foil. The thickness of the electrode conductor 11a may be 5 μm or more and 25 μm or less, for example, 10 μm. The electrode conductor 12a may be, for example, a copper foil. The thickness of the electrode conductor 12a may be 5 μm or more and 25 μm or less, for example, 10 μm.

[0021] FIG. 5 is a cross-sectional view showing the specific structures of the positive electrode active material layer 11b and the negative electrode active material layer 12b. As shown in FIG. 5, the positive electrode active material layer 11b may be a layer of a positive electrode material that is a mixture of a positive electrode active material 11c and a conductive additive 11d. The negative electrode active material layer 12b may be a layer of a negative electrode material that is a mixture of a negative electrode active material 12c and a conductive additive 12d. The positive electrode active material 11c may be, for example, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or lithium manganese oxide. The negative electrode active material 12c may be, for example, graphite or lithium titanate. The conductive additives 11d and 12d may be, for example, carbon black or acetylene black. However, the positive electrode active material 11c, the negative electrode active material 12c, and the conductive additives 11d and 12d are not limited to these.

[0022] The positive electrode material and the negative electrode material may have a clay-like property, in which a positive electrode active material 11c and a negative electrode active material 12c are mixed in an electrolyte containing conductive additives 11d and 12d, respectively. The positive electrode 11 may be an electrode in which the positive electrode material is coated on an electrode conductor 11a. The negative electrode 12 may be an electrode in which the negative electrode material is coated on an electrode conductor 12a.

[0023] The power generating unit 14 may further include a separator 13. The positive electrode 11, the negative electrode 12, and the separator 13 may be positioned such that the positive electrode active material layer 11b and the negative electrode active material layer 12b are in contact with the separator 13. That is, the unit cell 10 may have a structure in which the positive electrode 11 and the negative electrode 12 are stacked with the separator 13 interposed therebetween. The separator 13 may function as an insulating member that insulates the positive electrode 11 and the negative electrode 12. The separator 13 may be made of, for example, a nonwoven fabric or a porous material.

[0024] When a porous material is used as separator 13, specifically, a porous film made of a thermoplastic resin having a melting point of about 80° C. to 140° C. may be used. As the thermoplastic resin, for example, a polyolefin polymer such as polypropylene or polyethylene, or polyethylene terephthalate may be used.

[0025] The positive electrode material and the negative electrode material do not have to have clay-like properties. In this case, the positive electrode active material 11c and the negative electrode active material 12c do not need to be mixed with an electrolyte. In this case, the unit cell 10 may be filled with an electrolyte, and the electrolyte may be impregnated into the separator 13 and held therein.

[0026] However, when using positive and negative electrode materials with clay-like properties, a binder is not required between the positive and negative electrodes and the separator. Furthermore, an electrolyte is mixed into the positive and negative electrode materials before forming the positive and negative electrodes. This improves the performance of the positive and negative electrodes. By mixing the electrolyte into the positive and negative electrode materials, the number of steps required for forming the positive and negative electrodes can be reduced compared to when using positive and negative electrode materials that do not contain an electrolyte. Furthermore, the step of injecting the electrolyte can be eliminated from the manufacturing process of the energy storage device. Furthermore, compared to when using positive and negative electrode materials that do not contain an electrolyte, the positive and negative electrode materials can be applied thicker to the electrode conductors. Therefore, to realize an energy storage device with a predetermined energy storage capacity, fewer separators can be used than when using positive and negative electrode materials that do not contain clay-like properties. This reduces component costs and increases energy density.

[0027] Fig. 6 is a plan view of the first protective member 30 and its periphery of the energy storage device 1. As shown in Fig. 6, the exposed portion 11e may be a protruding portion that protrudes from the electrode conductor 11a when the electrode conductor 11a is viewed in plan. Furthermore, the exposed portion 12e may be a protruding portion that protrudes from the electrode conductor 12a when the electrode conductor 12a is viewed in plan. When the exposed portions 11e and 12e are protruding portions, the exposed portion 11e may be referred to as a first protruding portion, and the exposed portion 12e may be referred to as a second protruding portion.

[0028] The exposed portions 11e and 12e do not have to be protruding portions on the electrode conductors 11a and 12a, respectively. For example, a portion of the first housing 15 and a corresponding portion of a component other than the electrode conductor 11a may be cut out, so that the corresponding portion of the electrode conductor 11a functions as the exposed portion 11e. Alternatively, for example, a portion of the first housing 15 and a corresponding portion of a component other than the electrode conductor 12a may be cut out, so that the corresponding portion of the electrode conductor 12a functions as the exposed portion 12e.

[0029] Connecting portions 11f and 12f are located on exposed portions 11e and 12e. Connecting portion 11f is the portion where connecting terminal 21 and exposed portion 11e are connected and may be referred to as a first connecting portion. Connecting portion 12f is the portion where connecting terminal 22 and exposed portion 12e are connected and may be referred to as a second connecting portion.

[0030] The connecting portion 11f may be located at the center of the exposed portion 11e in the width direction of the exposed portion 11e when the connecting portion 11f is viewed in a plane. Furthermore, the connecting portion 12f may be located at the center of the exposed portion 12e in the width direction of the exposed portion 12e when the connecting portion 12f is viewed in a plane. The width direction of the exposed portion 11e is a direction perpendicular to the direction from the first housing 15 toward the connecting portion 11f when the exposed portion 11e is viewed in a plane. In each drawing, the X-axis direction corresponds to the width direction of the exposed portion 11e. Furthermore, the width direction of the exposed portion 12e is also the same as the width direction of the exposed portion 11e. However, the width direction of the exposed portion 11e may be any direction that can be considered perpendicular to the direction from the first housing 15 toward the connecting portion 11f when the exposed portion 11e is viewed in a plane, and does not have to be strictly perpendicular.

[0031] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6. For simplicity, in FIG. 2, the electrode conductors 11a are shown as being substantially parallel to one another. However, in an actual energy storage element 1, the electrode conductors 11a may approach one another as they are spaced further away from the first housing. As shown in FIG. 7, at the connection portion 11f, the exposed portions 11e exposed from the first housing 15 of each of the unit cells 10 may be electrically connected to one another. At the connection portion 12f, the exposed portions 12e exposed from the first housing 15 of each of the unit cells 10 may be electrically connected to one another. Specifically, the exposed portions 11e and the exposed portions 12e may be connected to one another by, for example, ultrasonic welding, laser welding, or resistance welding.

[0032] The first protective member 30 may protect the connection portions 11f and 12f. There is a risk that the surfaces of the connection portions 11f and 12f may be deformed during welding. If the deformed surfaces of the connection portions 11f and 12f come into contact with the second housing 50, there is a risk that the second housing 50 may be damaged. Furthermore, for example, if the second housing 50 is made of an aluminum pouch film, there is a risk that the film may be damaged and the connection portions 11f and 12f may come into contact with the aluminum inside, causing a short circuit. The first protective member 30 reduces the risk that the connection portions 11f and 12f may come into contact with the second housing 50, causing the above-mentioned damage and short circuit.

[0033] In the energy storage device 1, at least the connection portion 11f and a portion of the first housing 15 may be covered by a covering member from the connection portion 11f to a portion of the first housing 15. Also, at least the connection portion 12f and a portion of the first housing 15 may be covered by a covering member from the connection portion 12f to a portion of the first housing 15. In the first embodiment, the first protective member 30 may function as a covering member that covers at least the connection portion 11f and a portion of the first housing 15 from the connection portion 11f to a portion of the first housing 15. Also, the first protective member 30 may function as a covering member that covers at least the connection portion 12f and a portion of the first housing 15 from the connection portion 12f to a portion of the first housing 15.

[0034] 6 and 7, the first protective member 30 may cover not only the connecting portions 11f and 12f but also the end portion of the first housing 15. In the direction from the connecting portions 11f and 12f toward the first housing 15, the width d1 (see FIGS. 3 and 4) of the first housing 15 covered by the first protective member 30 may be, for example, not less than 0.5 mm and not more than 5 mm.

[0035] As a result, the region of exposed portion 11e from connecting portion 11f to first housing 15 may be covered by first protective member 30. Also, the region of exposed portion 12e from connecting portion 12f to first housing 15 may be covered by first protective member 30. In FIGS. 6 and 7, first housing 15 is spaced apart from connecting portions 11f and 12f. However, in the energy storage device 1, first housing 15 may be in contact with connecting portions 11f and 12f.

[0036] <Exposed portion 11e in energy storage element 9 of comparative example> FIG. 8 is a plan view showing an energy storage device 9 of a comparative example. FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 8. As shown in FIGS. 8 and 9, the energy storage device 9 differs from the energy storage device 1 in that the first housing 15 is not covered with the first protective member 30. Therefore, the exposed portion 11e of the energy storage device 9 has an area that is not covered with the first protective member 30. In the energy storage device 9, a damaged portion 11x, which is a portion where damage has occurred in the exposed portion 11e, may occur around such an area. When the length of the area not covered with the first protective member 30 is relatively short (for example, approximately 0.1 mm to 1 mm), the damaged portion 11x may occur.

[0037] Fig. 10 is a cross-sectional view showing an example of stress occurring in exposed portion 11e of energy storage element 9. In Fig. 10, the case where stress occurs substantially parallel to the planar direction of exposed portion 11e is indicated by reference numeral 1001. Furthermore, the case where stress occurs substantially perpendicular to the planar direction of exposed portion 11e is indicated by reference numeral 1002.

[0038] As indicated by reference numeral 1001 in Fig. 10, stress F1 may occur in the exposed portion 11e of the energy storage element 9 in a compressive direction substantially parallel to the planar direction of the exposed portion 11e. The stress F1 is concentrated in an area not covered by the first protective member 30. Therefore, there is a risk that the stress F1 may cause a damaged portion 11x in the exposed portion 11e. In the example indicated by reference numeral 1001 in Fig. 10, the damaged portion 11x is, for example, a portion where the exposed portion 11e is broken, occurring in the above-mentioned area of ​​the exposed portion 11e in a direction substantially perpendicular to the stress F1.

[0039] 10, in the energy storage element 9, stress F2 may also be generated in the exposed portion 11e where the damaged portion 11x has occurred, the stress F2 being substantially perpendicular to the planar direction of the exposed portion 11e. If stress F2 is generated on either the first housing body 15 or the first protective member 30, there is a risk of fracture occurring in the damaged portion 11x.

[0040] <Exposed portion 11e of energy storage element 1> FIG. 11 is a cross-sectional view showing an example of stress occurring at the exposed portion 11e of the energy storage device 1. As described above, in the energy storage device 1, as shown in FIG. 11, at least the connecting portion 11f and a portion of the first housing 15 are covered by the first protective member 30 from the connecting portion 11f to a portion of the first housing 15. Therefore, even if stress F1 occurs in a compressive direction substantially parallel to the planar direction of the exposed portion 11e, the concentration of the stress F1 at a specific location is reduced. This makes it less likely that a damaged portion like the damaged portion 11x that occurs in the energy storage device 9 will occur. Furthermore, in the exposed portion 12e, stress concentration at a specific location is reduced, making it less likely that a damaged portion will occur. In particular, when the first protective member 30 is used as a covering member, the size of the first protective member 30 can be changed so that the first protective member 30 covers the end of the first housing 15. This makes it possible to reduce the likelihood of a damaged portion occurring using a simple technique.

[0041] In particular, in the case where exposed portions 11e and 12e are protrusions as in the energy storage device 1, if a gap exists between the first housing 15 and the first protective member 30, the exposed portions 11e and 12e corresponding to the gap are likely to be damaged or broken. However, because the connecting portion 11f and a portion of the first housing 15 are covered by the first protective member 30, the exposed portions 11e and 12e are less likely to be damaged.

[0042] <Other Configurations of Energy Storage Element 1> 6, in the energy storage device 1, the exposed portion 11e and the exposed portion 12e may protrude in the same direction from the first housing 15. The first protective member 30 may be positioned across the exposed portion 11e and the exposed portion 12e. This allows the first protective member 30 to cover a larger area of ​​the first housing 15 than when the first protective member 30 is not positioned across the exposed portion 11e and the exposed portion 12e. This therefore allows for improved adhesion between the first protective member 30 and the first housing 15.

[0043] As shown in FIG. 6 , the energy storage device 1 may further include an adhesive member 40. The adhesive member 40 bonds the connection terminals 21 and 22 to the second housing 50 located above and below the connection terminals 21 and 22 to determine the positions of the connection terminals 21 and 22 relative to the second housing 50. The adhesive member 40 may be, for example, an adhesive film. The material of the adhesive member 40 may be, for example, polypropylene, ionomer, or ethylene vinyl acetate. The thickness of the adhesive member 40 may be, for example, 100 μm per side. "Per side" refers to the thickness of the adhesive member 40 that bonds the connection terminals 21 and 22 to one of the second housings 50 located above and below the connection terminals 21 and 22.

[0044] As shown in FIG. 6 , the adhesive member 40 may be spaced apart from the first protective member 30. Alternatively, the adhesive member 40 may be in contact with the first protective member 30. Positioning the adhesive member 40 and the first protective member 30 in this manner reduces the likelihood that the first protective member 30 will be affected by the expansion or contraction of the second housing 50 or the like due to heat, via the adhesive member 40. This reduces the likelihood that the electrode conductor 11a or the electrode conductor 12a will be damaged or broken due to such influence. For example, the distance between the adhesive member 40 and the first protective member 30 may be 0 mm or more and 0.5 mm or less.

[0045] However, in the energy storage device 1, the adhesive member 40 may overlap with the first protective member 30. When the adhesive member 40 overlaps with the first protective member 30, the width of the area where the adhesive member 40 overlaps with the first protective member 30 may be, for example, 0.5 mm or less.

[0046] As described above, the connection portion 11f may electrically connect multiple exposed portions 11e to each other. Furthermore, the connection portion 12f may electrically connect multiple exposed portions 12e to each other. Generally, the greater the number of exposed portions 11e connected by the connection portion 11f and the number of exposed portions 12e connected by the connection portion 12f, the greater the stress likely to be generated in the exposed portions 11e and 12e. In other words, the greater the risk of damage and breakage of the exposed portions 11e and 12e. However, in the energy storage device 1, the connection portion 11f and a portion of the first housing 15 are covered by the first protective member 30. Therefore, even in a structure in which multiple exposed portions 11e are connected by the connection portion 11f and multiple exposed portions 12e are connected by the connection portion 12f, the risk of damage and breakage of the exposed portions 11e and 12e is reduced.

[0047] As described above, the thickness of the first protective member 30 may be equal to or greater than the sum of the thickness of the first housing 15 and the thickness of the electrode conductors 11a and 12a. Having such a thickness for the first protective member 30 reduces bending of the exposed portions 11e and 12e due to stress generated in the exposed portions 11e and 12e. This further reduces the possibility of damage and breakage occurring in the exposed portions 11e and 12e.

[0048] As shown in Fig. 3, the connection terminal 21 may be connected to an exposed portion 11ea, which is one of the outermost exposed portions 11e among the multiple stacked exposed portions 11e. Also, as shown in Fig. 4, the connection terminal 22 may be connected to an exposed portion 12ea, which is one of the outermost exposed portions 12e among the multiple stacked exposed portions 12e. That is, the connection terminal 21 may be connected to one of the outermost electrode conductors 11a and 12a among the multiple stacked electrode conductors 11a and 12a.

[0049] 3 and 4, connection terminal 21 is connected to exposed portion 11ea located on the lower side in the Z direction, and connection terminal 22 is connected to exposed portion 12ea located on the upper side in the Z direction. However, the connection positions of connection terminals 21 and 22 are not limited to being different positions in the Z direction, and they may be connected to exposed portions 11ea and 12ea located on the same side (for example, the lower side in the Z direction).

[0050] One of the outermost exposed portions 11e and 12e is referred to as exposed portion 11ea and 12ea, respectively. The other of the outermost exposed portions 11e and 12e, opposite exposed portions 11ea and 12ea, is referred to as exposed portion 11eb and 12eb, respectively. When connection terminals 21 and 22 are connected to exposed portions 11ea and 12ea, the bending of exposed portions 11eb and 12eb is greatest. Therefore, damage and breakage are likely to occur in exposed portions 11eb and 12eb. However, by providing first protective member 30 to energy storage element 1, even when connection terminal 21 is connected to exposed portions 11ea and 12ea as described above, the occurrence of damage and breakage in exposed portions 11eb and 12eb can be reduced.

[0051] However, connection terminal 21 may be connected to exposed portion 11e other than exposed portion 11ea. Also, connection terminal 22 may be connected to exposed portion 12e other than exposed portion 12ea. In this case, the bending of exposed portions 11e and 12e is smaller than when connection terminals 21 and 22 are connected to exposed portions 11ea and 12ea, respectively.

[0052] <Manufacturing process of energy storage element 1> Fig. 12 is a flowchart showing an example of a manufacturing process for the energy storage device 1. It is assumed that the individual unit cells 10 have already been manufactured at the start of the flowchart shown in Fig. 12. It is also assumed that the second housing body 50 is made of two aluminum pouch films.

[0053] In the manufacturing process of the energy storage device 1, first, a plurality of unit cells 10 are stacked (S1). Next, connection terminals 21 and 22 are welded to the electrode conductors 11a and 12a of the stacked unit cells 10 (S2). Specifically, the exposed portions 11e of the plurality of electrode conductors 11a are welded together, and the connection terminal 21 is welded to the outermost exposed portion 11ea. Furthermore, the exposed portions 12e of the plurality of electrode conductors 12a are welded together, and the connection terminal 22 is welded to the outermost exposed portion 12ea.

[0054] Connection terminal 21 is welded to electrode conductor 11a, and connection terminal 22 is welded to electrode conductor 12a, thereby forming connection portions 11f and 12f. First protective member 30 is attached to connection portions 11f and 12f (S3). Furthermore, unit cells 10 are welded to each other at their outer peripheries (S4). Unit cells 10 may be welded to each other at their outer peripheries by ultrasonic welding, heat welding, or adhesive tape, for example.

[0055] Next, an aluminum pouch film, which is the material of the second housing body 50, is temporarily heat-sealed to the unit cells 10 whose peripheries have been welded (S5). The temporary heat-sealing is for determining the position of the aluminum pouch film relative to the unit cells 10. The temporary heat-sealing may be low-strength welding that allows it to be peeled off from the unit cells 10 as needed. After determining the position of the aluminum pouch film, three of the four sides of the approximately rectangular aluminum pouch film are welded (S6).

[0056] With the three sides of the aluminum pouch film welded, the aluminum pouch film is cut into a desired shape (S7). The interior of the aluminum pouch film is then vacuum-sealed (S8). During vacuum sealing, the last side of the aluminum pouch film is welded to form the second housing body 50, thereby manufacturing the energy storage device 1. The above-described steps may be reversed as necessary. For example, step S4 may be performed before step S2, or step S8 may be performed before step S7.

[0057] As described above, the energy storage device 1 according to the present disclosure can reduce the occurrence of damage and breakage in the exposed portions 11e and 12e. By reducing the occurrence of damage and breakage in the exposed portions 11e and 12e as described above, it is possible to save energy and resources that would otherwise be wasted in manufacturing an energy storage device in which such damage and breakage occurs. This can contribute to the achievement of the Sustainable Development Goals (SDGs).

[0058] [Embodiment 2] Fig. 13 is a cross-sectional view showing the configuration of a main part of an energy storage device 2 according to embodiment 2. The energy storage device 2 may have the same configuration as the energy storage device 1 with respect to components not shown in Fig. 13. As shown in Fig. 13, in the energy storage device 2, the first protective member 30 only needs to cover the connection portions 11f and 12f, and does not need to cover the first housing 15. The energy storage device 2 may further include a second protective member 35.

[0059] The second protective member 35 may be positioned so as to straddle the first housing 15 and the first protective member 30. The material and thickness of the second protective member 35 may be the same as the material and thickness of the first protective member 30 described above.

[0060] In the energy storage device 2, the covering member that protects the connection portions 11f and 12f and a portion of the first housing 15 may include a first protective member 30 and a second protective member 35 that is different from the first protective member 30. In this case, at least the connection portion 11f and a portion of the first housing 15 are covered by the first protective member 30 and the second protective member 35 from the connection portion 11f to a portion of the first housing 15. This reduces the concentration of stress generated in the exposed portions 11e and 12e at a specific location. This reduces damage and breakage of the electrode conductors 11a and 12a. In this case, the second protective member 35 may or may not cover the connection portions 11f and 12f.

[0061] [Embodiment 3] FIG. 14 is a plan view showing the configuration of a main part of an energy storage device 3 according to embodiment 3. The energy storage device 3 may have the same configuration as the energy storage device 1 with respect to components not shown in FIG. 14. As shown in FIG. 14, the energy storage device 3 may include a first covering member 31 and a second covering member 32 instead of the first protective member 30. The first covering member 31 is required to cover at least the connection portion 11f. The second covering member 32 is required to cover at least the connection portion 12f. Furthermore, each of the first covering member 31 and the second covering member 32 is required to further cover a portion of the first housing 15. By providing separate covering members such as the first covering member 31 and the second covering member 32, the possibility that stress generated in one of the electrode conductors 11a and 12a will affect the other can be reduced.

[0062] 14, the exposed portions 11e and 12e protrude in the same direction from the first housing 15. However, in the energy storage device 3, the exposed portions 11e and 12e may protrude in different directions, for example, opposite directions, from the first housing 15. In the energy storage device 3, even when the exposed portions 11e and 12e protrude in different directions from the first housing 15, the connecting portions 11f and 12f can be covered by the first covering member 31 and the second covering member 32, which are separate members. Furthermore, even when the exposed portions 11e and 12e do not protrude from the first housing 15, the exposed portions 11e and 12e may be located on different sides of the first housing 15, for example, on opposite sides. In other words, the energy storage device 3 provides an improved degree of freedom in the positions of the exposed portions 11e and 12e relative to the first housing 15.

[0063] [Embodiment 4] FIG. 15 is a plan view showing the configuration of the main part of the power storage element 4 according to Embodiment 4. The power storage element 4 may have the same configuration as that of the power storage element 1 for the configuration not shown in FIG. 15. As shown in FIG. 15, in the power storage element 4, the connection portion 11f may be located offset from the central portion of the exposed portion 11e in the width direction of the exposed portion 11e. As described above, the width direction of the exposed portion 11e is a direction substantially perpendicular to the direction from the first container 15 toward the connection portion 11f when the exposed portion 11e is viewed in plan. In each drawing, the X-axis direction corresponds to the width direction of the exposed portion 11e.

[0064] In the width direction of the exposed portion 11e, let the distance from the first end 11ec, which is one end of the exposed portion 11e, to the connection portion 11f be d21. Also, in the width direction of the exposed portion 11e, let the distance from the second end 11ed, which is the end on the opposite side of the first end 11ec of the exposed portion 11e, to the connection portion 11f be d22. "The connection portion 11f is located offset from the central portion of the exposed portion 11e" means that d21 and d22 are different from each other.

[0065] When the connection portion 11f is located offset from the central portion of the exposed portion 11e, damage and breakage are likely to occur at the end of the exposed portion 11e on the side far from the connection portion 11f. In FIG. 15, d21 < d22. In this case, compared with the first end 11ec, a large stress is likely to occur at the second end 11ed. However, since the first protective member 30 functions as a covering member, the occurrence of damage and breakage is reduced not only at the first end 11ec but also at the second end 11ed.

[0066] Further, the exposed portion 11e may have a mark 11g indicating information unique to the power storage element 4. The mark 11g is, for example, a two-dimensional code, but may also be a one-dimensional code (barcode). The mark 11g may be formed, for example, by irradiating the exposed portion 11e with a laser. Also, the unique information may be information indicating, for example, the manufacturing location, manufacturing time, or lot number. By having the mark 11g on the exposed portion 11e, the traceability of the power storage element 1 becomes possible.

[0067] 15, the exposed portion 11e has a mark 11g between the connecting portion 11f and the second end 11ed. Therefore, the size of the mark 11g can be made larger than when the mark 11g is provided between the connecting portion 11f and the first end 11ec. However, the exposed portion 11e may also have the mark 11g between the connecting portion 11f and the first end 11ec. Furthermore, the exposed portion 11e may have the mark 11g even when the connecting portion 11f is located in the center of the exposed portion 11e.

[0068] In addition, in energy storage element 4, exposed portion 12e may have mark 11g in addition to exposed portion 11e. In addition, in energy storage element 4, exposed portion 11e may not have mark 11g, and only exposed portion 12e may have mark 11g.

[0069] [Additional Notes] The invention according to the present disclosure has been described above based on the drawings and examples. However, the invention according to the present disclosure is not limited to the above-described embodiments. In other words, the invention according to the present disclosure can be modified in various ways within the scope of the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that a person skilled in the art can easily make various modifications or corrections based on the present disclosure. It should also be noted that these modifications or corrections are included in the scope of the present disclosure. [Explanation of symbols]

[0070] 1. Energy storage element 10 unit cells 11 Positive electrode 11a Electrode conductor 11e Exposed part (protruding part, first protruding part) 11f Connection (first connection) 12 Negative electrode 12a Electrode conductor 12e Exposed part (protruding part, second protruding part) 12f Connection (second connection) 14 Power generation body 15 First Containment Unit 21, 22 Connection terminals 30 First protective member (covering member) 31 First covering member 32 Second covering member 35 Second protective member (covering member) 50 Second Containment Unit

Claims

1. a power generator including a positive electrode and a negative electrode having electrode conductors; a first housing that houses the power generator; a connection terminal electrically connected to an exposed portion of the electrode conductor exposed from the first housing; a first protective member that protects a connection portion between the exposed portion and the connection terminal, a covering member covering at least the connection portion and a portion of the first housing from the connection portion to a portion of the first housing; When the exposed portion is viewed in a plane, if the width direction of the exposed portion is defined as a direction perpendicular to the direction from the first housing to the connection portion, the connection portion is positioned offset from the center of the exposed portion in the width direction of the exposed portion.

2. The energy storage device according to claim 1 , wherein the covering member is the first protective member.

3. The energy storage element according to claim 1 , wherein the covering member includes the first protective member and a second protective member different from the first protective member.

4. The energy storage element according to claim 1 , wherein the thickness of the covering member is equal to or greater than the sum of the thickness of the first container and the thickness of the electrode conductor.

5. In each of the positive electrode and the negative electrode, The electrode conductors are laminated in multiple layers, the connection terminal is connected to one of the two outermost electrode conductors in the stacked electrode conductors; The energy storage element according to claim 1 .

6. The energy storage element according to claim 1 , wherein the exposed portion is a protruding portion that protrudes from the electrode conductor when the electrode conductor is viewed in plan view.

7. the protrusion on the positive electrode is a first protrusion, When the protrusion on the negative electrode is a second protrusion, the first protrusion and the second protrusion protrude in the same direction from the first housing; The covering member is located across the first protruding portion and the second protruding portion. The energy storage element according to claim 6.

8. the connection portion of the positive electrode is a first connection portion, When the connection portion of the negative electrode is a second connection portion, The covering member includes a first covering member covering at least the first connection portion and a second covering member covering at least the second connection portion. The energy storage element according to claim 1 .

9. The exposed portion has a mark indicating information specific to the energy storage element. The energy storage element according to claim 1 .

10. a second housing that houses the first housing; an adhesive member that adheres the second housing and the connection terminal, The first protective member and the adhesive member are in contact with each other or spaced apart from each other. The energy storage element according to claim 1 .

11. a plurality of unit cells each including the power generating body and the first housing; In the connection portion, the exposed portions of the plurality of unit cells that are exposed from the first housing are electrically connected to each other. The energy storage element according to claim 1 .

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