Method for manufacturing battery, and battery

Abstract

To provide a method for manufacturing batteries, capable of suppressing occurrence of deformation or damage when an electrolyte is injected through a liquid injection port of a battery, and a battery.SOLUTION: A battery in which a plurality of electrodes are stacked includes a liquid injection port 31 for injecting an electrolyte to the electrode, and a liquid injection frame formed so as to surround the liquid injection port. A step T is formed on an end face of the liquid injection frame in a stacking direction of the electrodes. A method for manufacturing batteries includes a liquid injection step of supplying an electrolyte through a liquid injection frame that is formed so as to surround a liquid injection port for injecting the electrolyte to an electrode. A step is formed on an end face of the liquid injection frame in a stacking direction of a plurality of the electrodes. In the liquid injection step, a first jig 40 is disposed while pressing so as to cover an opening of the liquid injection frame, a second jig 41 is disposed to the step, and the electrolyte is supplied into the liquid injection port while generating opposing force by the first jig and the second jig against the liquid injection frame.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a battery and a battery.

Background Art

[0002] Patent Document 1 discloses that an injection port is provided at the end of a bipolar battery by injection molding.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When injecting the electrolytic solution from the injection port, it is necessary to press the injection frame formed so as to surround the injection port. However, if too much force is applied to the injection frame, there is a risk of damage or deformation to the injection frame.

[0005] Therefore, an object of the present disclosure is to provide a method for manufacturing a battery that can suppress deformation and breakage when injecting an electrolytic solution from an injection port of the battery. Also, a battery for that purpose is provided.

Means for Solving the Problems

[0006] Although details will be described later, as a result of intensive studies, the inventor has found that in order to ensure the sealing property of the electrolytic solution during injection of the electrolytic solution, when injecting, the injection frame is pressed from a direction intersecting the stacking direction of the battery. Since buckling and deformation are a concern, by adding a restraining force to the injection frame also from the stacking direction of the battery, the force due to pressing is canceled. However, it has been found that if the restraining force becomes large, damage or deformation will occur to the injection frame. In response to this, the inventor has embodied a means capable of reducing the pressing force even when the restraining force is reduced.

[0007] The present application discloses a method for manufacturing a battery in which a plurality of electrodes are stacked, the method having an electrolyte injection step of supplying an electrolyte through an electrolyte injection frame formed so as to surround an electrolyte injection port for injecting the electrolyte into the electrodes. Among the electrolyte injection frames, a step is formed on an end surface in the stacking direction of the plurality of electrodes. In the electrolyte injection step, a first jig is arranged by pressing so as to cover the opening of the electrolyte injection frame, and a second jig is arranged on the step, and the electrolyte is supplied to the electrolyte injection port while generating opposing forces on the electrolyte injection frame by the first jig and the second jig.

[0008] The present application discloses a battery in which a plurality of electrodes are stacked, the battery having an electrolyte injection port for injecting an electrolyte into the electrodes and an electrolyte injection frame formed so as to surround the electrolyte injection port. Among the electrolyte injection frames, a step is formed on an end surface in the stacking direction of the plurality of electrodes.

[0009] The height difference of the above step can be 0.5 mm or more.

Advantages of the Invention

[0010] According to the present disclosure, since opposing forces act between the second jig arranged on the step and the first jig pressing the opening of the electrolyte injection frame, the pressing force for obtaining the sealing property by the first jig can be reduced, and the occurrence of deformation and breakage of the electrolyte injection frame can be suppressed while ensuring the sealing property.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0012] 1. Structure of Battery First, the structure of a secondary battery 10 according to one example of the present disclosure will be described with reference to the drawings. The drawings also show the directions of a three-dimensional orthogonal coordinate system. Here, the xy plane is the horizontal plane, the z-axis direction is the vertical direction, and the larger one in the z-axis direction is upward.

[0013] FIG. 1 is a schematic external perspective view for explaining the structure of the secondary battery 10. In this embodiment, the secondary battery 10 is a bipolar lithium-ion secondary battery. As such, the secondary battery 10 has a plurality of metal conductive plates 11 and power storage modules 12, respectively, and these are alternately stacked and electrically connected to form a series connection. The secondary battery 10 is typically used for batteries such as hybrid vehicles and electric vehicles. In addition, both ends in the stacking direction (the z-axis direction in FIG. 1) of the stacking are conductive plates 11. A positive electrode terminal (not shown) is connected to the conductive plate 11 at one end in the stacking direction, and a negative electrode terminal (not shown) is connected to the conductive plate 11 at the other end in the stacking direction.

[0014] The power storage module 12 is a flat single battery as a whole, has front and back surfaces, and has side surfaces 12a forming a thickness.

[0015] 1.1. Internal Structure of Power Storage Module FIG. 2 shows a cross-sectional view schematically showing the internal structure of one power storage module 12 with attention focused thereon. In this embodiment, the power storage module 12 includes an electrode laminate L formed by stacking a plurality of bipolar electrodes 13, a plurality of sealing bodies 20 provided on each bipolar electrode 13, and a liquid injection portion 30 (see FIG. 1) which is a portion for injecting an electrolytic solution. The plurality of bipolar electrodes 13 are stacked along the thickness direction (the z-axis direction, the thickness direction in the flat plate shape), and the sealing bodies 20 are arranged on each bipolar electrode 13.

[0016] 1.1.1. Electrode laminate [Bipolar electrode] In the following description of each component, there may be descriptions of "upper surface" and "lower surface". However, in FIG. 2, the "upper surface" means the larger side in the z-axis direction, and the "lower surface" means the smaller side in the z-axis direction. This is for convenience of description, but the "upper surface" can be rephrased as the "first surface" and the "lower surface" as the "second surface". The bipolar electrode 13 includes a current collector foil 14, a positive electrode active material layer 15 (first active material layer) provided on the lower surface of the current collector foil 14, and a negative electrode active material layer 16 (second active material layer) provided on the upper surface of the current collector foil 14.

[0017] The current collector foil 14 is a foil-shaped conductive member, and for example, a metal foil is used. It does not have to be a single-layer metal foil, and a clad foil or a laminated foil in which different metal foils are laminated may be used. The type of metal is not particularly limited. For example, a foil in which an aluminum foil and a copper foil are laminated so that the upper surface is an aluminum layer and the lower surface is a copper layer can be mentioned. Other metals include titanium, nickel, stainless steel (such as SUS304, SUS316, SUS301, etc. defined in JIS G 4305:2015), steel (such as cold-rolled steel sheets (SPCC, etc.) defined in JIS G 3141:2005), etc.

[0018] The positive electrode active material layer 15 constitutes the positive electrode of the bipolar electrode 13 and is disposed on the lower surface of the current collector foil 14 via an adhesive layer such as acetylene black in this embodiment. The positive electrode active material layer 15 can contain a positive electrode active material, a conductive assistant, and a binder. Examples of the positive electrode active material include composite oxides, metal lithium, and sulfur. The composition of the composite oxide includes, for example, at least one of iron, manganese, titanium, nickel, cobalt, and aluminum, and lithium. Examples of the composite oxide include olivine-type lithium iron phosphate (LiFePO 4 ), LiCoO 2 , LiNiMnCoO 2 , etc. The binder serves to fasten the active material or the conductive aid to the surface of the current collector foil 14 and maintain the conductive network in the electrode. Examples of the binder include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber; thermoplastic resins such as polypropylene and polyethylene; imide resins such as polyimide and polyamideimide; alkoxysilyl group-containing resins; acrylic resins containing monomer units such as acrylic acid and methacrylic acid; styrene-butadiene rubber (SBR); carboxymethyl cellulose; alginates such as sodium alginate and ammonium alginate; water-soluble cellulose ester cross-linked products; starch-acrylic acid graft polymers; and the like. These binders can be used alone or in combination. Examples of the conductive aid include acetylene black, carbon black, graphite, and the like.

[0019] The negative electrode active material layer 16 constitutes the negative electrode of the bipolar electrode 13 and is disposed on the upper surface of the current collector foil 14 in this embodiment. The negative electrode active material layer 16 can contain a negative electrode active material, a conductive aid, and a binder. The conductive aid and the binder can be considered in the same manner as those in the positive electrode active material layer 15. Examples of the negative electrode active material include carbon such as graphite, artificial graphite, highly oriented graphite, mesocarbon microbeads, hard carbon, and soft carbon; metal compounds; elements that can be alloyed with lithium or compounds of such elements; boron-added carbon; and the like. Examples of the elements that can be alloyed with lithium include silicon and tin.

[0020] [Separator] Here, a separator 17 is disposed between adjacent bipolar electrodes 13. The separator 17 is, for example, a porous sheet or non-woven fabric containing a polymer that absorbs and retains a liquid electrolyte, and in this embodiment, it is disposed between the positive electrode active material layer 15 and the negative electrode active material layer 16 of the electrodes adjacent in the z-axis direction. Examples of the material constituting the separator 17 include polypropylene, polyethylene, polyolefin, polyester, etc. The separator 17 may have a single-layer structure or a multilayer structure. Examples of the electrolyte absorbed and held by the separator 17 include a liquid electrolyte (electrolyte solution) containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. When the separator 17 is impregnated with the electrolyte, as the electrolyte salt, LiClO 4 , LiAsF 6 , LiPF 6 , LiBF 4 , LiCF3SO 3 , LiN(FSO 2 ) 2 , LiN(CF 3 SO 2 ) 2 etc., known lithium salts can be used. Also, as the non-aqueous solvent, known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, ethers, etc. can be used.

[0021] [Sizes of each layer, etc.] The current collector foil 14, the positive electrode active material layer 15, the negative electrode active material layer 16, and the separator 17 are configured to have different sizes in plan view. More specifically, the current collector foil 14 is the largest, followed by the separator 17, then the negative electrode active material layer 16, and the positive electrode active material layer 17 is the smallest. As can be seen from FIG. 2, the current collector foil 14, the positive electrode active material layer 15, the negative electrode active material layer 16, and the separator 17 are arranged with their centers aligned in plan view, and the difference in size is manifested in the degree of edge protrusion (overhang). Therefore, the edge of the current collector foil 14 protrudes the most, and the edges of the separator 17, the negative electrode active material layer 16, and the positive electrode active material layer 15 protrude in this order from the inside.

[0022] To form the positive electrode active material layer 15 and the negative electrode active material layer 16 on the current collector foil 14, conventionally known methods such as a roll coating method, a die coating method, a dip coating method, a doctor blade method, a spray coating method, and a curtain coating method are used, for example. Specifically, an active material, a solvent, and, if necessary, a binder and a conductive aid are mixed to produce a slurry-like composition for forming an active material layer. After applying the composition for forming an active material layer to the upper and lower surfaces of the current collector foil 14, it is dried. The solvent is, for example, N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, or water.

[0023] [Laminated Structure of Electrode Stack] In the electrode stack L, the bipolar electrodes 13 adjacent to each other in the stacking direction (z-axis direction) of the electrodes are stacked so as to overlap with a separator 17 interposed between the positive electrode active material layer 15 of one bipolar electrode 13 and the negative electrode active material layer 16 of the other bipolar electrode 13. Here, the size of the electrode stack L in plan view (size in the xy plane direction) is not particularly limited, but it may be a large electrode stack L such as 1 m × 1 m.

[0024] In addition, the electrode stack L has a positive terminal electrode 18 at its upper end and a negative terminal electrode 19 at its lower end at the stacking direction ends of the stack formed by the bipolar electrodes 13. The positive terminal electrode 18 has the current collector foil 14 and the positive electrode active material layer 15 provided on the lower surface of the current collector foil 14. A separator 17 is interposed between the positive electrode active material layer 15 of the positive terminal electrode 18 and the negative electrode active material 16 of the adjacent bipolar electrode 13. The negative terminal electrode 19 has the current collector foil 14 and the negative electrode active material layer 16 provided on the upper surface of the current collector foil 14. A separator 17 is interposed between the negative electrode active material layer 16 of the negative terminal electrode 19 and the positive electrode active material layer 15 of the adjacent bipolar electrode 13. A conductive plate 11 is laminated on the current collector foil 14 of the positive terminal electrode 18 and the negative terminal electrode 19.

[0025] 1.1.2. Sealing Body The sealing member 20 is a member that seals the bipolar electrode 13 by being disposed at the outer peripheral end of the bipolar electrode 13. Accordingly, the sealing member 20 also seals between the bipolar electrodes 13 adjacent to each other in the stacking direction. In this embodiment, the sealing member 20 includes a first seal member 21, a second seal member 22, and a spacer 23.

[0026] [First Seal Member] The first seal member 21 is a frame-shaped member, and is disposed along the outer peripheral end (outer edge) of the bipolar electrode 13. Specifically, as can be seen from FIG. 2, the first seal member 21 is disposed and joined between the upper surface of the current collector foil 14 and the lower surface of the spacer 23 at the outer peripheral end of the bipolar electrode 13, so that the negative electrode active material layer 16 is disposed within its frame. In this embodiment, a predetermined interval is provided between the inner edge of the first seal member 21 and the negative electrode active material layer 16 to form a space S. On the other hand, the outer edge of the first seal member 21 is configured such that the first seal member 21 protrudes outside the current collector foil 14. In this embodiment, the peripheral edge of the separator 17 is welded and fixed to the first seal member 21.

[0027] The first seal member 21 has electrical insulation properties and can be made of a known resin material having electrolyte resistance, such as acid-modified polyethylene (acid-modified PE), acid-modified polypropylene (acid-modified PP), polyethylene, or polypropylene.

[0028] [Second Seal Member] The second seal member 22 is a frame-shaped member, and is disposed along the outer peripheral end (outer edge) of the bipolar electrode 13. Specifically, as can be seen from FIG. 2, the second seal member 22 is disposed and joined between the lower surface of the current collector foil 14 and the upper surface of the spacer 23 at the outer peripheral end of the bipolar electrode 13, so that the positive electrode active material layer 15 is disposed within its frame. In this embodiment, a predetermined gap is provided between the inner edge of the second sealing member 22 and the positive electrode active material layer 15, forming a space S. On the other hand, the outer edge of the second sealing member 22 is configured such that the second sealing member 22 protrudes outward from the current collector foil 14, and the upper surface of the second sealing member 22 is joined to the lower surface of the first sealing member 21. The material of the second sealing member 22 can be considered in the same way as that of the first sealing member 21.

[0029] [Spacer] The spacer 23 is a frame-shaped member, which is arranged along the outer peripheral end of the bipolar electrode 13. Specifically, as can be seen from FIG. 2, the spacer 23 is arranged between the first sealing member 21 and the second sealing member 22. By joining the adjacent first sealing member 21, spacer 23, and second sealing member, the space S of each cell is sealed. In this embodiment, the inner edge of the spacer 23 is arranged at a distance from the positive electrode active material layer 15 and the negative electrode active material layer 16. The outer edge of the spacer 23 protrudes outside the edge of the current collector foil 14, and its outer edge is joined to the first sealing member 21 and the second sealing member 22 of the adjacent sealing body 20. The material of the spacer 23 can be considered in the same way as that of the first sealing member 21.

[0030] 1.1.3. Liquid injection part The liquid injection part 30 is formed on a part of the side surface 12a of the power storage module 12, and is a part for injecting (liquid injection) the electrolytic solution into the power storage module 12. FIG. 3 shows an exploded perspective view (the sealing material 33 is omitted for clarity) of a part of the side surface 12a of one power storage module 12 in FIG. 1 where the liquid injection part 30 is arranged. FIG. 4 shows a cross-sectional view (the sealing material 33 is not separated) along the A-A line parallel to the z-axis in FIG. 3.

[0031] In this embodiment, the liquid injection part 30 has a liquid injection port 31, a liquid injection frame 32, and a sealing material 33.

[0032] [Liquid injection port] The liquid injection port 31 is an opening formed on the side surface 12a of the power storage module 12 and is formed on the side of the side surface 12a among the holes (not shown) that penetrate the sealing body 20 and communicate the space S with the outside. The liquid injection port 31 (through hole) can be provided one for each bipolar electrode 13, for example. In that case, the number of liquid injection ports 31 corresponding to the number of bipolar electrodes 13 provided is formed. As described above, since the plurality of bipolar electrodes 13 are laminated and the positions in the z-axis direction in FIG. 3 are different, the positions of the plurality of liquid injection ports 31 in the z-axis direction are also changed according to the positions of the bipolar electrodes 13.

[0033] In this embodiment, each liquid injection port 31 (through hole) is a horizontally long slit with a long side extending in the direction around the side surface 12a. This shape is not particularly limited, but since the shape of the space S communicated with by the through hole 31 is small in the lamination direction of the bipolar electrodes 13 (z-axis direction in FIG. 3) and large in the plane direction (xy plane direction in FIG. 3) due to its nature, by making the liquid injection port 31 (through hole) a slit, the injection of the electrolytic solution can be efficiently performed.

[0034] [Liquid injection frame] The liquid injection frame 32 is a frame-shaped member and is arranged on the side surface 12a. The liquid injection frame 32 is arranged so as to surround each liquid injection port 31. Thereby, a recess 32a having an opening surrounded by the liquid injection frame 32 with the thickness of the liquid injection frame 32 (the size in the y-axis direction in FIG. 3) having the side surface 12a having the liquid injection port 31 as the bottom is formed. Further, the surface 32b of the liquid injection frame 32 on the side opposite to the side in contact with the side surface 12a becomes a welding surface with the sealing body 33 and a contact surface with the first jig 40 described later.

[0035] In this embodiment, the liquid injection frame 32 has a rectangular outer frame 32c forming its outer shape, and the inside of the outer frame 32c is partitioned by a partition wall 32d to form each recess 32a. The outer frame 32c is a rectangular frame body along the xz plane and has a shape that extends long in the x-axis direction with respect to the z-axis direction. Also, each recess 32a partitioned by the partition wall 32d is long in the x-axis direction with respect to the z-axis direction.

[0036] The material constituting the liquid injection frame 32 is not particularly limited, but it is preferably made of resin, typically polyethylene. Such a liquid injection frame can be produced by injection molding.

[0037] In this embodiment, a step T is formed in at least a part (the part where the second jig 41 described later contacts) of the end face in the stacking direction (z-axis direction) of the electrodes in the electrode laminate L of the liquid injection frame 32. The degree of the depth of the step T (the height difference, the difference in the z-axis direction) is not particularly limited as long as the pressing force from the first jig 40 can be received by the second jig 41 as described later. However, from the viewpoint of ensuring a certain contact area between the surface T1 (the surface that crosses the smaller surface and the larger surface in the z-axis direction) forming the step T and the second jig 41, it is preferably 0.5 mm or more.

[0038] In this embodiment, as a preferred form, steps T are provided on both end faces of the liquid injection frame 32 in the z-axis direction. However, the step T may be provided on only one of the end faces.

[0039] [Sealing material] The sealing material 33 is a sheet-like sealing material, which is covered on the liquid injection frame 32 so as to cover the recess 32a formed by the liquid injection frame 32 and welded to the surface 32b. Thereby, it is possible to prevent the injected electrolyte from leaking from the secondary battery 10. The sealing material 33 may be formed of a known sheet. For example, an aluminum laminate sheet having a layer structure in which an aluminum foil is covered with resin is typical.

[0040] 2. Manufacturing method of secondary battery The secondary battery 10 can be manufactured, for example, by the manufacturing method S10 as shown in the flow in FIG. 5. As can be seen from FIG. 5, the manufacturing method S10 of the secondary battery includes a liquid injection step S11, a first charging step S12, a high-temperature aging step S13, and a sealing step S14. Details will be described below.

[0041] 2.1. Liquid injection step In the electrolyte injection step S11, an electrolyte is injected into the bipolar electrode 13. A diagram for explanation is shown in FIG. 6. FIG. 6 is a diagram from the same perspective as FIG. 4, and for ease of viewing, the reference numerals omitted can be referred to FIG. 4.

[0042] In the electrolyte injection step S11, with respect to the secondary battery 10 (the sealing material 33 is not welded) before the electrolyte injection, the first jig 40 is arranged so as to block the opening of the recess 32a and press the surface 32b (arrow F1 in FIG. 6). Thereby, after this, the sealing property when the electrolyte is supplied from the liquid supply device is ensured. Therefore, the first jig 40 is preferably made of a material with a small elastic modulus, and more preferably a viscoelastic material such as rubber. Note that the first jig 40 is provided with a flow path 40a through which air during vacuum suction and the electrolyte from the liquid supply device pass.

[0043] In accordance with this, the second jig 41 is arranged on the step T so as to catch on the surface T1 of the step T of the injection frame 32. Thereby, the influence of the pressing force F1 by the first jig 40 on the electrode laminate L can be greatly reduced. The second jig 41 is preferably made of a material with a large elastic modulus (high rigidity) so that deformation hardly occurs due to shear force, and examples thereof include metals such as stainless steel.

[0044] As described above, the sealing property during the injection of the electrolyte can be ensured by the first jig 40. On the other hand, the pressing force F1 by the first jig 40 can also exert a pressing force on the electrode laminate L as can be seen from its direction, and there is concern about the influence (deformation, etc.) on the electrode laminate L. In contrast, by arranging the second jig 41 so as to catch on the surface T1 of the step T of the injection frame 32, a force F2 that resists the pressing force F1 acts on the surface T1. Thereby, the pressing force F1 is reduced and the influence on the electrode laminate L can be reduced. Here, if the second jig 41 is used to apply a restraining force to simply clamp from both sides in the z-axis direction without providing the step T, it is necessary to increase the restraining force in order to resist the pressing force F1 applied by the first jig 40. However, if the restraining force is increased too much, the force for clamping the liquid injection frame 32 becomes too large, and there is a concern about deformation or damage of the liquid injection frame. On the other hand, in the present disclosure, by contacting the surface T1 of the step T with which the second jig 41 comes into contact so as to be caught, a force F2 that resists the pressing force F1 can be obtained regardless of the force in the z-axis direction. Therefore, it is possible to suppress the occurrence of deformation or damage of the liquid injection frame 32.

[0045] As described above, with the first jig 40 and the second jig 41 arranged as described above, a liquid supply device is connected to the side of the first jig 40 opposite to the liquid injection frame 32. Vacuum pumping is performed on the bipolar electrode 13 through the flow path 40a by a vacuum pump via a vacuum suction pipe with the valve arranged in the liquid supply device opened, and the valve is closed to maintain a decompressed state. In that state, the valve of the liquid supply pipe is opened, and the electrolytic solution is sent from the liquid supply pipe through the flow path 40a, the recess 32a, the liquid injection port 31, through the through hole, and into the bipolar electrode 13, and the electrolytic solution is injected into the bipolar electrode 13.

[0046] 2.2. Initial charging process In the initial charging process S12, the first charging is performed. The conditions of the initial charging process are not particularly limited and are as known.

[0047] 2.3. High-temperature aging process Next, the high-temperature aging process S13 is performed. The process of high-temperature aging is as known. For example, the secondary battery 10 is conditioned by a procedure such as leaving it standing at 65°C for 15 hours.

[0048] 2.4. Sealing process In the sealing process S14, the sealing material 33 is placed over the injection frame 32 so as to cover the recess 32a formed by the injection frame 32, and the sealing material 33 is welded to the surface 32b of the injection frame 32. The welding method is not particularly limited, and examples include a method of pressing a heating body and irradiation with a laser.

Explanation of reference numerals

[0049] 10…secondary battery, 11…current collector plate, 12…power storage module, 13…bipolar electrode, 20…sealing body, 30…liquid injection part, 31…liquid injection port, 32…liquid injection frame, 33…sealing material, 40…first jig, 41…second jig, T…step

Claims

1. A method for manufacturing a battery in which a plurality of electrodes are stacked, comprising a liquid injection step of supplying an electrolytic solution through a liquid injection frame formed so as to surround a liquid injection port for injecting the electrolytic solution into the electrode, wherein a step is formed on an end face in the stacking direction of the plurality of electrodes among the liquid injection frames, and in the liquid injection step, a first jig is arranged by pressing so as to cover an opening of the liquid injection frame, a second jig is arranged on the step, and the electrolytic solution is supplied to the liquid injection port while generating a facing force between the first jig and the second jig with respect to the liquid injection frame. A method for manufacturing a battery.

2. A battery in which a plurality of electrodes are stacked, comprising a liquid injection port for injecting an electrolytic solution into the electrode, and a liquid injection frame formed so as to surround the liquid injection port, wherein a step is formed on an end face in the stacking direction of the plurality of electrodes among the liquid injection frames. A battery.

3. The battery according to claim 2, wherein a height difference of the step is 0.5 mm or more.

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