JP2011258439A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery in which a short circuit due to displacement of an electrode from a separator is suppressed.SOLUTION: The secondary battery comprises a lamination type electrode body where positive electrode plates and negative electrode plates are stacked via a separator, the separator being folded zigzag between the positive electrode plates and the negative electrode plates and having protrusions composed of a water-soluble polymer on its surfaces that are folded and face each other. The secondary battery has protrusions on a surface of the separator that faces the electrode plates, the protrusions regulating displacement of the electrode plates and thereby suppressing a short circuit due to displacement of the electrode plates from the separator.

Description

  The present invention relates to a secondary battery, and more particularly, to a secondary battery including an electrode body in which a separator interposed between a positive electrode and a negative electrode is interposed in a zigzag manner.

  Secondary batteries are classified into a stacked type and a wound type depending on the structure of an electrode body having a positive electrode and a negative electrode. In the laminated type, a separator is cut into pieces and formed into a size larger than that of a positive electrode and a negative electrode, and both electrodes are separated using this separator to prevent a short circuit. For this reason, generation | occurrence | production of the dust and increase of the usage-amount were needed by shaping | molding of the separator. Further, in order to prevent a short circuit, it is necessary to make the width of one pole smaller than the other pole (for example, make the width of the positive electrode smaller than that of the negative electrode).

  In addition, since the winding core requires a winding core at the time of molding, the space corresponding to this winding core does not contribute to the generation of electromotive force, and this space becomes a factor that hinders downsizing of the battery (The charge / discharge amount per volume could not be increased).

  In order to solve such a problem, Patent Document 1 discloses a battery in which a separator is bent zigzag so as to sew between electrodes between a positive electrode sheet and a negative electrode sheet.

  However, in this battery (electrode body structure), a short circuit may occur due to a separator misalignment during stacking. Specifically, in a state where there is no deviation between the separator and the electrode during lamination, both surfaces of the electrode are covered with the separator. However, when the separator is displaced, the end of the electrode is not covered by the separator (the surface is exposed). When this exposed surface comes into contact with another electrode (especially an opposing electrode) or a conductive member (such as a case), a short circuit occurs.

JP 2002-329530 A

  The present invention has been made in view of the above circumstances, and in a secondary battery including an electrode body in which a separator interposed between a positive electrode and a negative electrode is folded back in a zigzag manner, the electrode is separated from the separator. It is an object to provide a secondary battery in which a short circuit is suppressed.

  In order to solve the above-mentioned problems, the present inventors have studied the occurrence of the deviation between the separator and the electrode, and as a result, have reached the present invention.

  That is, the secondary battery of the present invention is a secondary battery having a laminated electrode body in which a positive electrode plate and a negative electrode plate are laminated via a separator, and the separator zigzags between the positive electrode plate and the negative electrode plate. The separator is folded, and the separator has protrusions made of a water-soluble polymer on opposing surfaces that are folded and face each other.

  The secondary battery of the present invention is a secondary battery including a separator zigzag-folded between a positive electrode plate and a negative electrode plate, and a protrusion is provided on a surface of the separator facing the electrode plate. And this protrusion part controls the shift | offset | difference of an electrode plate. As a result, a short circuit due to a displacement between the position of the electrode plate and the separator is suppressed.

  Furthermore, since a short circuit can be prevented, the sizes of the positive electrode plate and the negative electrode plate can be made comparable. As a result, the secondary battery of the present invention exhibits the effect of suppressing the coarsening of the physique.

It is the top view which showed the electrode plate used for the nonaqueous electrolyte battery of an Example. It is the side view which showed the electrode plate used for the nonaqueous electrolyte battery of an Example. It is the top view which showed the separator used for the nonaqueous electrolyte battery of an Example. It is the side view which showed the separator used for the nonaqueous electrolyte battery of an Example. It is the figure which showed the positive electrode plate and separator at the time of the assembly | attachment of the nonaqueous electrolyte battery of an Example. It is the figure which showed the positive electrode plate and separator at the time of the assembly | attachment of the nonaqueous electrolyte battery of an Example. It is the figure which showed the state which turned the separator along the positive electrode plate at the time of the assembly | attachment of the nonaqueous electrolyte battery of an Example. It is the figure which showed the state which has arrange | positioned the negative electrode plate at the time of the assembly | attachment of the nonaqueous electrolyte battery of an Example. It is the figure which showed the state which has arrange | positioned the negative electrode plate at the time of the assembly | attachment of the nonaqueous electrolyte battery of an Example. It is the figure which showed the state which laminated | stacked the positive electrode plate and the negative electrode plate at the time of the assembly | attachment of the nonaqueous electrolyte battery of an Example. It is the figure which showed the state which laminated | stacked the positive electrode plate and the negative electrode plate at the time of the assembly | attachment of the nonaqueous electrolyte battery of an Example. It is the figure which showed the separator used for the nonaqueous electrolyte battery of the 1st modification of an Example. It is the figure which showed the separator used for the nonaqueous electrolyte battery of the 2nd modification of an Example.

  The secondary battery of the present invention is a secondary battery having a laminated electrode body in which a positive electrode plate and a negative electrode plate are laminated via a separator.

  The separator is folded back zigzag between the positive electrode plate and the negative electrode plate. In addition, the separator has protrusions made of a water-soluble polymer on opposing surfaces that are folded back and face each other.

  In the secondary battery of the present invention, the separator is folded back zigzag between the positive electrode plate and the negative electrode plate. With such a configuration, the number of cutting parts for molding the separator is reduced, and generation of dust in the separator and increase in the amount of separator used can be suppressed. In the present invention, the state where the separator is folded back zigzag means that the separator is folded back at least once, and the folded-back separator sandwiches the positive electrode plate or the negative electrode plate. In other words, the state in which the separator is folded back in a zigzag pattern may be a state in which the separator is folded back at least once, and is preferably a state in which the separator is folded back multiple times. When a plurality of separators are folded back, the positive electrode plate and the negative electrode plate are alternately sandwiched.

  The secondary battery of the present invention has protrusions made of a water-soluble polymer on opposing surfaces that face each other when the separator is folded back. When the separator is folded, a pair of opposed surfaces formed by folding are opposed to each other. A positive electrode plate or a negative electrode plate (electrode plate) is disposed between the opposing surfaces.

  The secondary battery of the present invention has a protrusion made of a water-soluble polymer on the opposite surface. By having the protrusion, when the electrode plate disposed between the opposing surfaces of the separator is about to be displaced from the separator, the electrode plate comes into contact with the protrusion, and the displacement is restricted. That is, the secondary battery of this invention can suppress the short circuit of an electrode plate by restrict | regulating the shift | offset | difference of the electrode plate arrange | positioned between the separators. Furthermore, the secondary battery of this invention can prevent a short circuit because a separator has a projection part, and can make each size of a positive electrode plate and a negative electrode plate comparable. As a result, the secondary battery of the present invention exhibits the effect of suppressing the coarsening of the physique.

  In the secondary battery of the present invention, the protrusion is formed of a water-soluble polymer, so that it does not dissolve in the secondary battery electrolyte (nonaqueous electrolyte). The type of the water-soluble polymer that forms the protrusion is not particularly limited, and examples thereof include polymers such as styrene butadiene gum (SBR), polytetrafluoroethylene (PTFE), and an acrylic acid polymer.

  Each electrode plate has a current collector plate and an electrode active material layer formed on the surface of the current collector plate, and the protrusion is formed at a position in contact with the end of the electrode active material layer Is preferred. By forming the protrusion at a position where the protrusion contacts the end of the electrode active material layer, the protrusion contacts the end of the electrode active material layer and regulates the displacement of the electrode active material layer. Thereby, the shift | offset | difference of the electrode plate which has an electrode active material layer is controlled.

  The position where the protrusion is formed may be a position where it can be in contact with the end of the electrode active material layer, and is more preferably a position where the end surface of the end of the electrode active material layer is in contact with the side surface of the protrusion. . In addition, when the protrusion is formed at a position where it comes into contact with the end face of the electrode active material, a decrease in the contact area between the electrode active material layer and the separator surface can be suppressed. In addition, stress concentration in the electrode active material layer is eliminated, and damage to the electrode active material layer is suppressed.

  It is preferable that the protrusion is formed at a position where the protrusions provided on the facing surface overlap each other when the separator is folded back. Since the protrusions are provided at positions where the protrusions overlap each other, the protrusions of the separator overlap each other when the separator is folded back, and the displacement of the electrode plate can be further regulated.

  The protrusions may be formed so as to protrude from the surface of the separator so as to regulate the displacement of the electrode plate, and the form (shape) is not particularly limited.

  The protrusion may be in a shape where the electrode plate and the protrusion are in contact with each other at least at one place, and more preferably in a shape where the protrusion is in contact with a plurality of places or in a line shape.

  It is preferable that the protrusion is formed in a linear shape extending along the direction in which the separator extends. When the protrusion is formed in a line extending along the direction in which the separator extends, the protrusion is formed at a position where the line protrusions overlap when the separator is folded back. Furthermore, when the protrusion is linear in the direction in which the separator extends, the protrusion can be accurately and easily formed by applying a water-soluble polymer in the direction in which the separator extends.

  The protrusion height of the protrusion may be formed so as to protrude from the surface of the separator so as to regulate the displacement of the electrode plate, and the protrusion height is not particularly limited.

  The protrusion height of the protrusion from the surface of the separator is 50% of the total thickness of the current collector plate and the electrode active material layer, and the thickness of the electrode active material layer of the electrode facing the electrode with which the protrusion contacts. It is preferable that the value is equal to or less than the total value. The protrusion height of the protrusion from the surface of the separator is 50% of the total thickness of the current collector plate and the electrode active material layer, and the thickness of the electrode active material layer of the electrode facing the electrode with which the protrusion contacts. When the separator is folded back zigzag and the protrusions overlap, the thickness of the folded portion of the separator does not exceed the thickness between the electrode plates. Does not cause a decrease in adhesion. In other words, if the protrusion height of the protrusion exceeds this value, a gap is generated between the separator and the electrode plate due to the thickness of the separator, the stacking thickness increases, and the volume density of the electrode body decreases. .

  The protrusion is preferably formed by applying a water-soluble polymer to the separator when the separator is folded and laminated between the positive electrode plate and the negative electrode plate. By forming the protrusion when the separator is folded back, the protrusion can be formed at the same time as the electrode plates are stacked, and an increase in cost required for manufacturing can be suppressed.

  The secondary battery of the present invention is not limited as long as the separator folded back zigzag has a protrusion, and may be a capacitor. The secondary battery of the present invention is more preferably a non-aqueous electrolyte secondary battery. The type of the non-aqueous electrolyte secondary battery is not limited, but is preferably a lithium ion secondary battery.

  The secondary battery of the present invention is preferably an assembled battery in which a plurality of unit cells are combined.

  The secondary battery of the present invention is preferably a non-aqueous electrolyte battery having a positive electrode and a negative electrode and an electrolyte, and more preferably a lithium ion secondary battery. The positive electrode and the negative electrode may be formed by forming on the surface of the current collector an electrode mixture layer in which an additive selected from active materials, binders, conductive materials, and other materials as necessary is mixed. preferable.

  In the secondary battery of the present invention, the active material for the positive electrode or the negative electrode can be used by mixing with a compound used as an active material in a conventional secondary battery.

An example of such a compound is a lithium-containing transition metal oxide that is a positive electrode active material of a lithium ion secondary battery. The lithium-containing transition metal oxide is a material capable of removing and inserting Li ions (Li ⁺ ), and can include a lithium-metal composite oxide having a layered structure or a spinel structure. Specific examples include metal oxide materials such as Li _1-Z NiO ₂ , Li _1-Z MnO ₂ , Li _1-Z Mn ₂ O ₄ , and Li _1-Z CoO ₂ . Furthermore, examples of Li _1-Z βPO ₄ include LiFePO _4, and examples thereof include compounds containing one or more of them. Z represents a number from 0 to 1. In addition, each metal oxide-based material may be Li, Mg, Al, or a material in which a transition metal such as Co, Ti, Nb, or Cr is added or substituted. Furthermore, these lithium-metal composite oxides may be used alone or in combination.

  The binder is desirably formed of a polymer material, and is desirably a material that is chemically and physically stable in the atmosphere in the secondary battery. Examples of the binder include polyvinylidene fluoride, polytetrafluoroethylene (PTFE), and carboxymethyl cellulose (CMC).

  Examples of the conductive material include ketjen black, acetylene black, carbon black, graphite, carbon nanotube, and amorphous carbon. Further, conductive polymer polyaniline, polypyrrole, polythiophene, polyacetylene, polyacene and the like can be mentioned.

  As a method of forming an electrode mixture layer on the surface of the current collector, an electrode mixture having an active material, a binder, and a conductive material is dispersed or dissolved in an appropriate dispersion medium, and then the surface of the current collector The method of applying and drying can be mentioned.

When the secondary battery of the present invention is a lithium ion secondary battery, a compound that absorbs lithium ions during charging and releases them during discharging can be used as the active material of the negative electrode. The negative electrode active material is not particularly limited in its material configuration, and known materials and configurations can be used. Examples thereof include carbon materials such as lithium metal, graphite or amorphous carbon, alloy materials containing silicon and tin, and oxide materials such as Li ₄ Ti ₅ O ₁₂ and Nb ₂ O ₅ .

  The electrolytic solution is not particularly limited, and an electrolytic solution in which a supporting salt is dissolved in a solvent such as an organic solvent, an ionic liquid that is liquid itself, or a supporting salt that is further dissolved in the ionic liquid. I can give you.

  As an organic solvent, the organic solvent used for the electrolyte solution of a normal lithium ion secondary battery can be mention | raise | lifted. Examples thereof include carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, lactones, oxolane compounds and the like. In particular, it is preferable to use propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, or a mixed solvent thereof. Among these organic solvents, in particular, one or more non-aqueous solvents selected from the group consisting of carbonates and ethers are excellent in the solubility, dielectric constant and viscosity of the supporting salt, and the charge / discharge efficiency of the battery is also high. It is preferable because it is high.

An ionic liquid will not be specifically limited if it is an ionic liquid normally used for the electrolyte solution of a lithium secondary battery. For example, the cation component of the ionic liquid, or N- methyl -N- propyl piperidinium, and dimethyl ethyl methoxy ammonium cations like, and an anionic _{component, BF 4 -, N (SO} 2 CF 3) ₂ etc. can be mentioned.

In the lithium ion secondary battery, the supporting salt used for the electrolytic solution is not particularly limited. For example, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , Examples of the salt compound include LiC (CF ₃ SO ₂ ) ₃ , LiSbF ₆ , LiSCN, LiClO ₄ , LiAlCl ₄ , NaClO ₄ , NaBF ₄ , NaI, and derivatives thereof. Among these, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiN (FSO ₂ ) ₂ , LiN (CF ₃ One or more selected from the group consisting of a derivative of SO ₂ ) (C ₄ F ₉ SO ₂ ), a derivative of LiCF ₃ SO _3, a derivative of LiN (CF ₃ SO ₂ ) _{2 and} a derivative of LiC (CF ₃ SO ₂ ) ₃ It is preferable to use a salt from the viewpoint of electrical characteristics.

  In a lithium ion secondary battery, it is preferable to interpose a separator, which is a member that achieves both electrical insulation and ion conduction, between the positive electrode and the negative electrode. When the supporting electrolyte is liquid, the separator also serves to hold the liquid supporting electrolyte. Examples of the separator include a porous synthetic resin film, particularly a porous film of polyolefin polymer (polyethylene, polypropylene). Furthermore, it is preferable that the separator has a larger size than the positive electrode and the negative electrode for the purpose of ensuring the insulation between the positive electrode and the negative electrode.

  The secondary battery of the present invention is preferably composed of other elements in addition to the above elements.

  Hereinafter, the present invention will be described using examples.

  As an example of the present invention, a non-aqueous electrolyte secondary battery was manufactured.

(Example)
First, a positive electrode active material, a conductive material, a solvent, and a binder were mixed until uniform to prepare a slurry-like positive electrode mixture. And it apply | coated and dried on the surface of the positive electrode electrical power collector which consists of aluminum foil, and the positive electrode plate 1 was manufactured.

  The negative electrode active material was added to the solvent and the binder, and mixed until uniform to prepare a slurry negative electrode mixture. And it apply | coated and dried on the surface of the negative electrode collector which consists of copper foils, and the negative electrode plate 2 was manufactured.

  As shown in FIGS. 1 and 2, the manufactured positive electrode plate 1 and negative electrode plate 2 are provided with uncoated portions 11 and 21 to which no electrode mixture is applied (the active material layers 10 and 20 are not formed on the surface). It has a square shape at one end. As shown in FIG. 1, the uncoated portions 11, 21 of the electrode plates 1, 2 are disposed at one end in the longitudinal direction (long side direction) of the rectangular electrode plates 1, 2. It is formed by the method which does not apply | coat, and the method of scraping off the electrode mixture after drying.

  Next, the manufactured electrode plates 1 and 2 are laminated while interposing the separator 3 in a zigzag state while forming the protrusions 4 on the separator 3.

  The separator 3 is a band-shaped member made of a porous resin, and the band-shaped width is slightly longer than the length of the active material layers 10 and 20 in the longitudinal direction of the electrode plates 1 and 2. And as shown in FIGS. 3-4, the separator 3 has the protrusion part 4 formed of the water-soluble polymer (poly (sodium acrylate)) in the edge part of the width direction. As shown in the cross-sectional view of FIG. 4, the protrusion 4 (40, 41) is formed on the surface 3a of one end 3A in the width direction of the separator 3 and the back surface 3b of the other end 3B. Is done. Moreover, the protrusion part 4 is formed in the cross-sectional square shape.

  The protrusions 4 are formed by continuously passing the strip-shaped separator 3 through a coating device having a head capable of coating a water-soluble polymer solution at a predetermined position to solidify the water-soluble polymer. That is, the protrusion 4 is formed in a linear shape extending in the length direction of the strip-shaped separator 3. The protrusion 4 is formed over the entire length of the strip-shaped separator 3.

  The separator 3 on which the protrusions 4 are formed is laminated in a state of being interposed between the electrode plates 1 and 2.

  In the lamination of the electrode plates 1 and 2 and the separator, first, the positive electrode plate 1 is disposed on the surface 3 a of the separator 3. The state where the positive electrode plate 1 is arranged on the surface 3a of the separator 3 is shown in FIGS. At this time, in a state where the end portion (the end portion of the positive electrode active material layer 10) where the uncoated portion 11 in the longitudinal direction of the positive electrode plate 1 is not in contact with the side surface of the protrusion portion 40 of the surface 3 a of the separator 3. Be placed. In this state, the positive electrode active material layer 10 of the positive electrode plate 1 is in a state of being overlapped with the separator 3 (a state in which the positive electrode active material layer 10 is covered with the separator 3). Further, the uncoated portion 11 of the positive electrode plate 1 protrudes from the other end 3B side of the separator 3 in a state extending in the direction (short direction) perpendicular to the longitudinal direction of the separator 3. Here, the width of the separator 3 is only slightly longer than the length of the positive electrode active material layer 10 in the longitudinal direction, and the separator 3 is formed in a shape that substantially matches the positive electrode active material layer 10. Is in a state of hardly overlapping the uncoated portion 11.

  Then, the separator 3 is folded along the end 1C in the direction perpendicular to the longitudinal direction of the positive electrode plate 1 (the direction of the short side of the square) (folded around the end 1C) (FIG. 7). The folded separator 3 has a surface 3 a that contacts the surface of the positive electrode plate 1. Further, the tips of the protrusions 40 on the surface 3a of the separator 3 that overlap each other come into contact with each other. The separator 3 folded back along the positive electrode plate 1 is positioned on the uppermost surface where the back surface 3b is laminated.

  Next, the negative electrode plate 2 is disposed on the back surface 3 b of the separator 3. The state in which the negative electrode plate 2 is disposed on the back surface 3b of the separator 3 is shown in FIGS. At this time, the end of the negative electrode plate 2 where the uncoated portion 21 in the longitudinal direction is not formed (the end of the negative electrode active material layer 20) is in contact with the side surface of the protrusion 41 on the back surface 3b of the separator 3. Be placed. In this state, the negative electrode active material layer 20 of the negative electrode plate 2 is in a state of being overlapped with the separator 3 (a state in which the negative electrode active material layer 20 is covered with the separator 3). The uncoated portion 21 of the negative electrode plate 2 protrudes from the one end 3 </ b> A side of the separator 3 in a state extending in a direction perpendicular to the longitudinal direction of the separator 3. The protruding direction of the uncoated portion 21 of the negative electrode plate 2 is opposite to the protruding direction of the uncoated portion 11 of the positive electrode plate 1. Here, the width of the separator 3 is only slightly longer than the length of the negative electrode active material layer 20 in the longitudinal direction, and the separator 3 is formed in a shape that substantially matches the negative electrode active material layer 20. Is in a state of hardly overlapping the uncoated portion 21.

  Then, the separator 3 is folded back along the end 2D in the direction perpendicular to the longitudinal direction of the negative electrode plate 2 (in the direction of the short side of the square) (folded around the end 2D) (FIG. 9). The back surface 3 b of the separator 3 that is folded back contacts the surface of the negative electrode plate 2. Further, the tips of the protrusions 41 on the back surface 3b of the separator 3 that overlap each other come into contact with each other. The separator 3 folded back along the negative electrode plate 2 is located on the uppermost surface where the surface 3a is laminated.

  The above-described lamination process of the positive electrode plate 1 and the negative electrode plate is repeated, the electrode plates 1 and 2 are laminated in a predetermined number of laminations, and a laminated electrode body having a separator zigzag folded between the positive electrode plate and the negative electrode plate Was formed (FIGS. 10 and 11).

  The manufactured laminated electrode body was enclosed in a case together with a non-aqueous electrolyte, and the non-aqueous electrolyte secondary battery of this example was manufactured.

  The non-aqueous electrolyte secondary battery of the present embodiment has protrusions 4 on opposing surfaces 3a and 3b facing each other when the separator 3 is folded back. By having the protruding portion 4, the electrode plates 1 and 2 disposed between the opposing surfaces 3 a and 3 b of the separator 3 come into contact with the protruding portion 4 when attempting to shift the separator 3. The deviation is regulated. By restricting the displacement of the electrode plates 1 and 2, short-circuiting of the electrode plates 1 and 2 could be suppressed.

  In the nonaqueous electrolyte secondary battery of this example, the protrusion 4 of the separator 3 can prevent the electrode plates 1 and 2 from being short-circuited, and the respective sizes (sizes) of the positive electrode plate 1 and the negative electrode plate 2 can be set. It can be about the same. As a result, the non-aqueous electrolyte secondary battery of this example was prevented from becoming coarse.

  The non-aqueous electrolyte secondary battery of this example has a configuration in which the separator 3 is folded back in a zigzag manner between the positive electrode plate 1 and the negative electrode plate 2, and the number of cutting points for forming the separator 3 is reduced. Generation | occurrence | production of the dust of the separator 3 and the increase in the usage-amount of the separator 3 can be suppressed.

(First variant)
This form is the same as that of the nonaqueous electrolyte secondary battery of an Example except the form of the projection part 4 of the separator 3 differing.

  In this embodiment, as shown in FIG. 12, the protrusions 4 are formed on the separator 3 at intervals. The protrusion 4 is formed to have the same length as the width of the electrode plates 1 and 2.

(Second variant)
This form is the same as that of the nonaqueous electrolyte secondary battery of an Example except the form of the projection part 4 of the separator 3 differing.

  In this embodiment, as shown in FIG. 13, the protrusions 4 are formed on the separator 3 at intervals. The protrusion 4 is formed so as to contact the electrode plates 1 and 2 at a plurality of locations.

  Also in the first and second modified embodiments, the protrusion 4 can regulate the displacement of the electrode plates 1 and 2, and the same effect as in the example was exhibited.

  Further, in the first and second modified embodiments, it is not necessary to form the protrusion 4 on the folded portion of the separator 3 (particularly on the inner surface side to be folded), and the separator 3 and the electrode plates 1 and 2 are not folded when folded. The end portion will be in close contact, and the displacement can be further regulated.

  In addition, since the protrusion 4 is not formed over the entire length of the separator 3, the amount of water-soluble resin used for forming the protrusion 4 can be reduced.

1: Positive electrode 10: Positive electrode active material layer 11: Uncoated portion 2: Negative electrode 20: Negative electrode active material layer 21: Uncoated portion 3: Separator 4, 40, 41: Projection

Claims (6)

A secondary battery having a laminated electrode body in which a positive electrode plate and a negative electrode plate are laminated via a separator,
The separator is zigzag folded between the positive electrode plate and the negative electrode plate,
The separator has a protrusion made of a water-soluble polymer on opposing surfaces that are folded back and face each other. Each of the electrode plates has a current collector plate and an electrode active material layer formed on the surface of the current collector plate,
2. The secondary battery according to claim 1, wherein the protrusion is formed at a position in contact with an end of the electrode active material layer.   The secondary battery according to claim 1, wherein the protrusion is formed at a position where the protrusions provided on the facing surface overlap each other when the separator is folded.   The secondary battery according to claim 1, wherein the protrusion is formed in a linear shape extending along a direction in which the separator extends.   The protruding height of the protruding portion from the surface of the separator is 50% of the total thickness of the current collector plate and the electrode active material layer, and the height of the electrode facing the electrode with which the protruding portion abuts. The secondary battery according to any one of claims 1 to 4, which is not more than a total value of thickness values of the electrode active material layer.   The protrusion is formed by applying the water-soluble polymer to the separator when the separator is folded and laminated between the positive electrode plate and the negative electrode plate. The secondary battery as described.

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