JP6562726B2 - Rectangular secondary battery and manufacturing method thereof - Google Patents

Description

  The present invention relates to a rectangular secondary battery and a method for manufacturing the same.

  2. Description of the Related Art Conventionally, secondary batteries such as lithium ion secondary batteries and nickel metal hydride batteries are mounted on electrical products such as notebook computers and portable terminals. Further, as a power source for electric vehicles, hybrid vehicles and the like, lithium ion secondary batteries having a higher energy density than other secondary batteries are generally used. As an example of such a secondary battery, a positive and negative electrode sheet in which an electrode active material is held on a long foil-shaped current collector is wound together with a separator to form an electrode body, and the wound electrode body is used as an electrolyte. In addition, a wound-type prismatic secondary battery housed in a prismatic battery case is known (see, for example, Patent Document 1 below).

  In the invention described in Patent Document 1, each layer of a current collector laminated portion in which foil-shaped current collectors are laminated is sufficiently bonded, and the current collecting terminal is hardly peeled from the current collector laminated portion. In order to solve this problem, the following configuration is disclosed. At least one of the current collector laminated parts of the positive and negative current collectors formed at both ends of the wound electrode body is joined to the current collector terminal by ultrasonic welding.

  As another example of a wound-type prismatic secondary battery, a battery that has a problem of reducing the electrical resistance between an electrode body and a current collector is disclosed (for example, see Patent Document 2 below). In the prismatic secondary battery described in Patent Document 2, a welded portion and a pressure contact portion are provided at a lead portion of the electrode body and a connecting portion of the current collector. In the welded portion, the lead portion is welded and connected to the leg portion of the current collector. The press contact part is arranged inside the electrode body relative to the weld part. In the press contact portion, a plurality of uncoated portions constituting the lead portion press the legs of the current collector by, for example, cold press contact.

JP 2010-282846 A JP2015-37041A

  In a square secondary battery, for example, in order to improve capacity and energy density, it may be required to increase the number of windings of the electrode in the winding body or to reduce the height dimension. Such an increase in the number of windings of the wound body and a reduction in the height dimension are factors that increase the thickness of the flat wound body. When the thickness of the wound body is increased, like the prismatic secondary battery described in Patent Document 1, the current collector laminated portion of one electrode is bundled together in the thickness direction and collected by ultrasonic welding. It may be difficult to join the terminal.

  When the thickness of the winding body is increased, the lead part of one pole of the electrode body is divided into two as in the rectangular secondary battery described in Patent Document 2, and the divided part is divided into two parts. Each can be welded together. Thus, when the lead part of the wound body is divided into two parts and bundled and joined at the welded part, the uncoated part is deformed at the inner side in the winding axis direction, that is, the part on the electrode mixture layer side. The amount is relatively large. In addition, the deformation amount of the uncoated portion is relatively small on the outer side in the winding axis direction of the wound body, that is, on the end side in the winding axis direction of the foil exposed portion of the electrode.

  Therefore, in the uncoated part, the stress acting on the inner part in the winding axis direction is larger than the stress acting on the outer part in the winding axis direction, and the inner part in the winding axis direction is cut. It becomes easy. In order to reduce the stress which acts on such an uncoated part, it is possible to reduce the area of a welding part. However, when the area of the welded portion is reduced, not only the electric resistance increases, but also the bonding strength of the lead portion of the electrode body decreases.

  The present invention has been made in view of the above problems, and in the wound body in which the electrode is wound, when the portion where the foil exposed portion of the electrode is laminated is divided into two and joined, the foil exposed portion An object of the present invention is to provide a prismatic secondary battery that can suppress an increase in electrical resistance while preventing cutting.

  In order to achieve the above object, the prismatic secondary battery of the present invention includes a flat wound body in which an electrode is wound around a winding axis, and one end and the other end of the winding body in the winding axis direction. A rectangular secondary battery comprising: a joined portion in which the foil exposed portion of the electrode is bundled in two on both sides of the winding axis in the thickness direction of the winding body, The body has a curved portion in which the electrode is curved and laminated on both sides of the winding axis direction and the height direction perpendicular to the thickness direction, and the joint portion is an inner surface on the winding axis side. In at least one of the outer surfaces opposite to the winding axis, at least one of the curved portion and the end adjacent to the height direction in the winding axis direction end side of the winding body, The electrode layer side of the electrode at the end is disposed so as to be separated from the curved portion in the height direction. That. In other words, the prismatic secondary battery according to the present invention includes a flat wound body in which an electrode is wound around a winding axis, and the electrode laminated at one end and the other end in the winding axis direction of the wound body. A rectangular secondary battery comprising: a foil-exposed portion of the winding body divided into two on both sides of the winding axis in the thickness direction of the winding body; In at least one of the inner surface on the rotation axis side and the outer surface on the opposite side to the winding axis, the dimension in the height direction perpendicular to the winding axis direction and the thickness direction is toward the mixture layer side of the electrode. It is characterized by decreasing gradually.

  According to the prismatic secondary battery of the present invention, in the wound body in which the electrode is wound, when the portion where the foil exposed portion of the electrode is laminated is divided and joined, the foil exposed portion is prevented from being cut. However, an increase in electrical resistance can be suppressed.

1 is an external perspective view of a prismatic secondary battery according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of a lid assembly and a wound body of the rectangular secondary battery shown in FIG. 1. The disassembled perspective view of the winding body shown in FIG. Sectional drawing which shows the state which joined the winding body shown in FIG. 2 to the current collector. The side view of the winding body seen from the arrow V direction shown in FIG. The side view equivalent to FIG. 5 which shows the modification 1 of the square secondary battery shown in FIG. The side view equivalent to FIG. 5 which shows the modification 2 of the square secondary battery shown in FIG. The side view equivalent to FIG. 5 which shows the modification 3 of the square secondary battery shown in FIG. The side view equivalent to FIG. 5 which shows the modification 4 of the square secondary battery shown in FIG. The side view equivalent to FIG. 5 which shows the modification 5 of the square secondary battery shown in FIG. The side view equivalent to FIG. 5 which shows the modification 6 of the square secondary battery shown in FIG. Explanatory drawing of the manufacturing method of the square secondary battery shown in FIG.

[Square secondary battery]
Hereinafter, embodiments of the prismatic secondary battery of the present invention will be described in detail with reference to the drawings. In addition, in order to make an understanding of this invention easy, the reduced scale of each part in drawing may be changed suitably. In the following description, up, down, left, and right are convenient directions for explaining the positional relationship between the members, and do not necessarily correspond to the vertical direction or the horizontal direction.

  FIG. 1 is an external perspective view of a prismatic secondary battery 100 according to an embodiment of the present invention. 2 is an exploded perspective view of the lid assembly and the wound body 30 of the prismatic secondary battery 100 shown in FIG. In the following, the winding axis direction X parallel to the winding axis A that is the winding center axis of the wound body 30 wound with the electrode is the X axis, the thickness direction Y of the flat wound body 30 is the Y axis, Description will be made using an XYZ orthogonal coordinate system in which the height direction Z perpendicular to the winding axis direction X and the thickness direction Y is the Z axis.

  The rectangular secondary battery 100 of the present embodiment is mainly composed of a flat rectangular battery container 10, a pair of external terminals 20 arranged outside the battery container 10, and a flat bag housed inside the battery container 10. A rotating body 30 and a pair of current collecting plates 40 that electrically connect the external terminal 20 and the wound body 30 are provided. Although details will be described later, the prismatic secondary battery 100 of the present embodiment is provided in the foil laminated portions 31d and 32d of the wound body 30 and the shapes of the joint portions 31e and 32e that are joined to the current collector plate 40. It has the characteristics.

  The battery container 10 includes a bottomed rectangular tube-shaped battery can 11 having an opening at the top, and a battery lid 12 that closes the opening of the battery can 11. The battery container 10 can be manufactured by, for example, aluminum or an aluminum alloy, and the battery can 11 can be manufactured by, for example, deep-drawing these materials. The battery can 11 includes a generally rectangular flat bottom wall 11b, a pair of rectangular wide side walls 11a along the longitudinal direction of the bottom wall 11b, and a pair of rectangular narrow side walls 11c along the short direction of the bottom wall 11b. Have.

  The battery lid 12 is a flat plate member having a substantially rectangular planar shape, and is joined to the opening of the battery can 11 by laser welding, for example, so as to close the opening of the battery can 11. Yes. The battery cover 12 is provided with external terminals 20 at both ends in the longitudinal direction along the winding axis direction X, and a gas discharge valve 13 and a liquid injection port 14 at an intermediate portion in the longitudinal direction.

  The gas discharge valve 13 is formed by, for example, pressing the battery lid 12 to make it thin, or joining a thin film member to an opening provided in the battery lid 12 by laser welding or the like. The gas discharge valve 13 is cleaved when the internal pressure of the battery container 10 rises above a predetermined pressure to reduce the internal pressure of the battery container 10. The liquid injection port 14 is provided for injecting the non-aqueous electrolyte into the battery container 10 in which the battery can 11 is closed by the battery lid 12. After the non-aqueous electrolyte is injected, the injection plug 15 is inserted by, for example, laser welding. It is sealed by joining.

  One of the pair of external terminals 20 is a positive external terminal 20A made of, for example, aluminum or an aluminum alloy, and the other is a negative external terminal 20B made of, for example, copper or a copper alloy. Each external terminal 20 is electrically connected to the battery lid 12 via an external insulator 21 arranged outside the battery container 10 and an internal insulator and a gasket (not shown) arranged inside the battery container 10. Is electrically insulated. Each external terminal 20 includes a connection bolt 22, a terminal plate 23, and a connection member 24.

  The terminal plate 23 is a plate-like member disposed on the upper surface of the battery lid 12 with the external insulator 21 interposed therebetween, and extends in the longitudinal direction of the battery lid 12 so that a constriction is formed at the center. The terminal plate 23 has two through holes arranged in the longitudinal direction across the constriction at the center, and the connection bolt 22 is inserted from one through hole upward from below, and the other through hole is inserted. The connection member 24 is inserted through the top from below.

  The connecting member 24 is a columnar member that penetrates the terminal plate 23 and the battery lid 12, and the upper end portion that protrudes from the through hole of the terminal plate 23 is plastically deformed and crimped on the upper surface of the terminal plate 23. 23 is electrically connected. For example, the connection bolt 22 is inserted into a through-hole or notch provided in a bus bar (not shown) that connects the external terminals 20 of the plurality of rectangular secondary batteries 100, and a nut is screwed into the bus bar so that the bus bar is externally connected. The terminal 20 can be fixed and electrically connected.

  One of the pair of current collector plates 40 is a positive electrode current collector plate 40A made of, for example, aluminum or an aluminum alloy, and the other is a negative electrode current collector plate 40B made of, for example, copper or a copper alloy. Each current collecting plate 40 is electrically insulated from the battery lid 12 via an internal insulator and a gasket disposed inside the battery container 10. Each current collecting plate 40 includes a base portion 41 disposed substantially parallel to the battery lid 12 and a pair of connection pieces 42 connected to electrodes constituting the wound body 30.

  The base 41 of the current collector plate 40 is formed in a substantially rectangular flat plate shape having the longitudinal direction of the battery lid 12 as the longitudinal direction and the short direction of the battery lid 12 as the transverse direction, and is inserted through the connection member 24 of the external terminal 20. It has a through hole. The connection piece 42 of the current collector plate 40 is provided at the longitudinal end of the base 41 on the short side of the battery lid 12, is bent downward on both sides in the short direction of the base 41, and is connected to the wide side wall 11 a of the battery can 11. Are formed in a pair of plates that hang down toward the bottom wall 11 b of the battery can 11.

  The portion of the current collector plate 40 joined to the lower winding body 30 of the pair of connection pieces 42 has an outer side in the winding axis direction X so that the interval between the pair of connection pieces 42 gradually increases. The flat wound body 30 is bent toward the outside in the thickness direction Y. That is, the lower part of the pair of connection pieces 42 of the current collector plate 40 has a narrow interval on the central side in the longitudinal direction of the battery lid 12 when viewed from the direction perpendicular to the upper or lower surface of the battery lid 12. The lid 12 is bent so as to form a V-shape having a wide interval on the end side in the longitudinal direction of the lid 12 toward the end side in the longitudinal direction of the battery lid 12. Further, the pair of connection pieces 42 of the current collector plate 40 are provided approximately symmetrically with the winding axis A of the winding body 30.

  The same-polarity external terminal 20 and the current collector plate 40 are electrically connected by a connection member 24 of the external terminal 20. Specifically, the connection member 24 of the external terminal 20 that has passed through the through hole of the battery lid 12 is inserted into the through hole of the base 41 of the current collector plate 40 and penetrates the base 41. The lower end of the connecting member 24 of the external terminal 20 penetrating the base 41 of the current collector plate 40 is caulked by plastic deformation at the lower surface of the base 41 of the current collector 40. Thereby, the external terminal 20 of the same polarity and the current collector plate 40 are electrically connected by the connection member 24 of the external terminal 20.

  The external terminal 20, the current collector plate 40, the external insulator 21, the gasket and the internal insulator are integrally fixed to the battery lid 12 by caulking the upper end and the lower end of the connection member 24 of the external terminal 20, and the battery A lid assembly is formed together with the lid 12. The positive electrode current collector plate 40A and the negative electrode current collector plate 40B each have a foil laminate portion 31d of the positive electrode 31 provided at one end in the winding axis direction X of the winding body 30 via a pair of connection pieces 42, It is joined to the foil laminated portion 32d of the negative electrode 32 provided at the other end.

  FIG. 3 is an exploded perspective view showing a state in which an end portion on the winding end side of the wound body 30 of the rectangular secondary battery 100 shown in FIG. 2 is developed.

  In the prismatic secondary battery 100 of the present embodiment, the wound body 30 includes a shaft core 35 for winding the positive electrode 31, the negative electrode 32, and the separators 33 and 34. The shaft core 35 is a substantially rectangular flat plate-shaped member corresponding to the planar shape of the wound body 30, and the winding axis A is the center line. The shaft core 35 can be made of an insulating material such as PP (polypropylene) resin, PBT (polybutylene terephthalate) resin, PPS (polyphenylene sulfide) resin, PEEK (polyether ether ketone) resin, or the like.

  The wound body 30 is a flat winding obtained by winding a belt-like positive electrode 31 and a negative electrode 32, which are stacked with belt-like separators 33 and 34 interposed therebetween, around a flat shaft core 35 parallel to the winding axis A. It is a rotating electrode group. That is, the wound body 30 is a flat wound body in which the electrode is wound around the winding axis A.

  The separators 33 and 34 insulate the positive electrode 31 and the negative electrode 32, and the separator 34 is wound outside the negative electrode 32 wound around the outermost periphery. The separators 33 and 34 can be made of, for example, a polyolefin-based resin material. Specifically, the separators 33 and 34 are made of a porous resin material containing at least one of a polypropylene resin material and a polyethylene resin.

  The wound body 30 includes a pair of flat portions 30a on both sides of the thickness direction Y in which the positive electrode 31 and the negative electrode 32 are flatly stacked, and the positive electrodes 31 and the negative electrodes 32 on both sides in the height direction Z of the flat portion 30a. It has a pair of semi-cylindrical curved portions 30b that are bent and stacked. The pair of curved portions 30 b are formed on both sides of the winding body 30 in the height direction Z perpendicular to the winding axis direction X and the thickness direction Y. The wound body 30 is inserted into the battery can 11 so that the winding axis A is parallel to the bottom wall 11 b and the wide side wall 11 a of the battery can 11, and the pair of flat portions 30 a are the pair of wide side walls of the battery can 11. The pair of curved portions 30 b are disposed to face the battery lid 12 and the bottom wall 11 b of the battery can 11.

  The positive electrode 31 includes a positive electrode foil 31a that is a positive electrode current collector, and a positive electrode mixture layer 31b formed by applying a positive electrode active material mixture on both surfaces of the positive electrode foil 31a. One side in the width direction of the positive electrode 31 is an uncoated portion where the positive electrode mixture layer 31b is not formed, and is a foil exposed portion 31c where the positive foil 31a is exposed. In the positive electrode 31, the foil exposed portion 31 c is arranged on the opposite side of the winding axis direction X from the foil exposed portion 32 c of the negative electrode 32, and is wound around the axis 35 around the winding axis A. .

  The positive electrode 31 is, for example, a positive electrode active material mixture kneaded by adding a conductive material, a binder and a dispersion solvent to the positive electrode active material, and applied to both surfaces of the positive electrode foil 31a except for one side in the width direction. It can be produced by drying, pressing and cutting. As the positive electrode foil 31a, for example, an aluminum foil having a thickness of about 20 μm can be used. The thickness of the positive electrode mixture layer 31b not including the thickness of the positive electrode foil 31a is, for example, about 90 μm.

As a material of the positive electrode active material mixture, for example, 100 parts by weight of lithium manganate (chemical formula LiMn ₂ O ₄ ) is used as the positive electrode active material, 10 parts by weight of flaky graphite as the conductive material, and 10% by weight as the binder. Part of polyvinylidene fluoride (hereinafter referred to as PVDF) and N-methylpyrrolidone (hereinafter referred to as NMP) can be used as a dispersion solvent. The positive electrode active material is not limited to the above-described lithium manganate. For example, another lithium manganate having a spinel crystal structure, or a lithium manganese composite oxide partially substituted or doped with a metal element may be used. Further, as the positive electrode active material, lithium cobaltate or lithium titanate having a layered crystal structure, and a lithium-metal composite oxide obtained by substituting or doping a part thereof with a metal element may be used.

  The negative electrode 32 includes a negative electrode foil 32a that is a negative electrode current collector, and a negative electrode mixture layer 32b that is formed by applying a negative electrode active material mixture on both surfaces of the negative electrode foil 32a. One side in the width direction of the negative electrode 32 is an uncoated portion where the negative electrode mixture layer 32b is not formed, and is a foil exposed portion 32c where the negative foil 32a is exposed. In the negative electrode 32, the foil exposed portion 32 c is disposed on the opposite side of the winding axis direction X from the foil exposed portion 31 c of the positive electrode 31, and is wound around the axis 35 around the winding axis A. .

  The negative electrode 32 is, for example, applied to a negative electrode active material mixture kneaded by adding a binder and a dispersion solvent to the negative electrode active material on both sides of the negative electrode foil 32a except one side in the width direction, dried, pressed, It can be produced by cutting. As the negative electrode foil 32a, for example, a copper foil with a thickness of about 10 μm can be used. The thickness of the negative electrode mixture layer 32b not including the thickness of the negative electrode foil 32a is, for example, about 70 μm.

As a material for the negative electrode active material mixture, for example, 100 parts by weight of amorphous carbon powder as the negative electrode active material, 10 parts by weight of PVDF as the binder, and NMP as the dispersion solvent can be used. The negative electrode active material is not limited to the above-mentioned amorphous carbon, and natural graphite capable of inserting and removing lithium ions, various artificial graphite materials, carbonaceous materials such as coke, and compounds such as Si and Sn (for example, , SiO, TiSi ₂ or the like), or a composite material thereof. The particle shape of the negative electrode active material is not particularly limited, and a particle shape such as a scale shape, a spherical shape, a fiber shape, or a lump shape can be appropriately selected.

  The binder used for the positive electrode mixture layer 31b and the negative electrode mixture layer 32b is not limited to PVDF. Examples of the binder include polytetrafluoroethylene (PTFE), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, and vinyl fluoride. Polymers such as vinylidene fluoride, propylene fluoride, chloroprene fluoride, and acrylic resins, and mixtures thereof may be used.

  In the winding axis direction X of the wound body 30, the width of the negative electrode mixture layer 32 b of the negative electrode 32 is wider than the width of the positive electrode mixture layer 31 b of the positive electrode 31. A negative electrode 32 is wound around the innermost and outermost circumferences of the wound body 30. Thereby, the positive electrode mixture layer 31b is sandwiched between the negative electrode mixture layer 32b from the innermost periphery to the outermost periphery of the wound body 30.

  The wound body 30 is provided with electrode foil laminated portions 31 d and 32 d for joining the current collector plate 40 to both ends in the winding axis direction X. More specifically, a foil laminated portion 31d of the positive electrode 31 in which the foil exposed portion 31c of the positive electrode 31 is wound and laminated is provided at one end portion in the winding axis direction X of the wound body 30, At the other end in the winding axis direction X, a foil laminated portion 32d of the negative electrode 32 is provided in which the foil exposed portion 32c of the negative electrode 32 is wound and laminated.

  FIG. 4 is a cross-sectional view showing a state where the wound body 30 shown in FIG. 2 is joined to the current collector plate 40. FIG. 5 is a side view of the wound body 30 and the current collector plate 40 as seen from the direction of the arrow V shown in FIG. 4 and 5 show the configuration on the negative electrode side, and the configuration on the positive electrode side having the same configuration as that on the negative electrode side is denoted by parenthesized reference numerals and the illustration is omitted.

  As described above, the rectangular secondary battery 100 according to the present embodiment includes the foil exposed portions 31c and 32c of the positive electrode 31 and the negative electrode 32 that are stacked at one end and the other end of the winding body 30 in the winding axis direction X. That is, it has the foil lamination | stacking parts 31d and 32d. In addition, the rectangular secondary battery 100 includes joint portions 31e and 32e in which the foil laminated portions 31d and 32d are bundled in two on both sides of the winding axis A in the thickness direction Y of the wound body 30.

  The current collector plate 40 has a pair of connection pieces 42 that are joined to the joint portions 31 e and 32 e of the wound body 30. In addition, the prismatic secondary battery 100 of the present embodiment includes a metal plate 50 that is joined to the joints 31e and 32e with the joints 31e and 32e of the winding body 30 sandwiched between the connection pieces 42 of the current collector plate 40. It has. In the metal plate 50, the positive electrode metal plate 50 </ b> A fixed to one end of the shaft core 35 in the winding axis direction X of the wound body 30 is made of, for example, aluminum or an aluminum alloy, and is connected to the other end of the shaft core 35. The fixed negative electrode metal plate 50B is made of, for example, copper or a copper alloy. Hereinafter, when it is not necessary to distinguish the positive electrode metal plate 50 </ b> A and the negative electrode metal plate 50 </ b> B, these will be described as the metal plate 50. The thickness of the metal plate 50 is, for example, thicker than the positive electrode foil 31 a or the negative electrode foil 32 a and thinner than the thickness of the current collector plate 40.

  In the present embodiment, the shaft core 35 is provided with a groove 35a at one end and the other end in the winding axis direction X. The groove 35a has a predetermined depth in the winding axis direction X from the end surface in the winding axis direction X of the shaft core 35, the groove width near the bottom is constant, and a V-shaped inclined surface in the vicinity of the opening. Is formed, and the groove width in the vicinity of the opening is enlarged. In the rectangular secondary battery 100 of the present embodiment, the end of the metal plate 50 is sandwiched and fixed by a groove 35 a provided in the shaft core 35. In addition, the metal plate 50 includes a first portion 51 and a second portion which are expanded so as to divide the foil laminated portion 32d into two on both sides of the winding axis A in the thickness direction Y of the flat wound body 30. A portion 52 is provided.

  The foil laminated portions 31 d and 32 d of the wound body 30 bundled in two are between the pair of connection pieces 42 of the current collector plate 40 and the first portion 51 and the second portion 52 of the metal plate 50. In the sandwiched state, the current collector plate 40 and the metal plate 50 are joined by, for example, ultrasonic pressure welding to form joints 31e and 32e. In the prismatic secondary battery 100 of the present embodiment, the connection piece 42 of the current collector plate 40 is joined to the outer surfaces 31f and 32f opposite to the winding axis A of the joint portions 31e and 32e. The part 51 and the second part 52 are joined to the inner surfaces 31g and 32g on the winding axis A side of the joints 31e and 32e.

  When the metal plate 50 is not fixed to the shaft core 35, the connecting piece 42 of the current collector plate 40 is joined to the inner surfaces 31g and 32g on the winding axis A side of the joint portions 31e and 32e, and the metal plate 50 is attached. You may join to the outer surfaces 31f and 32f on the opposite side to the winding axis | shaft A of the junction parts 31e and 32e. That is, the current collector plate 40 may be bonded to either the inner surfaces 31g, 32g or the outer surfaces 31f, 32f of the bonding portions 31e, 32e.

  Thereby, the winding body 30 is connected to the external terminal 20 provided outside the battery container 10 via the current collector plate 40 connected to the joint portions 31e and 32e. More specifically, in the wound body 30, the positive electrode 31 is electrically connected to the positive external terminal 20A via the positive current collector 40A, and the negative electrode 32 is connected to the negative external terminal via the negative current collector 40B. It is electrically connected to 20B and fixed to the lid assembly via the current collector plate 40.

  Here, as shown in FIG. 3, in the winding axis direction X parallel to the winding axis A of the winding body 30, the width of the separators 33 and 34 is wider than the width of the negative electrode mixture layer 32b. 31 and the foil exposed portions 31c and 32c of the negative electrode 32 protrude outward in the width direction from the end portions in the width direction of the separators 33 and 34, respectively. Therefore, the separators 33 and 34 do not hinder ultrasonic contact between the foil laminated portions 31 d and 32 d of the positive electrode 31 and the negative electrode 32 to the current collector plate 40 and the metal plate 50.

  As shown in FIGS. 3 and 5, in the prismatic secondary battery 100 of the present embodiment, the joint portions 31e and 32e of the wound body 30 have both the curved portions 30b and the height direction Z on the inner surfaces 31g and 32g. The positive electrode 31 and the negative electrode 32 on the side of the mixture layers 31b and 32b of the winding body 30 at the ends in the winding axis direction X at the ends on both sides in the height direction Z adjacent to Is arranged so as to be separated from the curved portion 30b in the height direction Z. In other words, the joining portions 31e and 32e of the wound body 30 have the positive electrode 31 and the negative electrode 32 having a dimension H in the height direction Z perpendicular to the winding axis direction X and the thickness direction Y on the inner surfaces 31g and 32g. The foil exposed portions 31c and 32c are gradually reduced from the end side in the winding axis direction X toward the mixture layers 31b and 32b. In other words, in the joint portions 31e and 32e, the dimension H in the height direction Z gradually decreases from the outer side to the inner side in the winding axis direction X.

  Accordingly, the dimension H in the height direction Z of the joining portions 31e and 32e of the wound body 30 is the end of the foil exposed portions 31c and 32c in the winding axis direction X, that is, the outer end in the winding axis direction X. It is maximum at the edge, and is minimum at the side of the mixture layers 31 b and 32 b of the positive electrode 31 and the negative electrode 32, that is, at the inner edge in the winding axis direction X. Here, the outside in the winding axis direction X means the end portion side of the winding body 30 in the winding axis direction X with reference to an arbitrary position on the winding body 30. Further, the inside of the winding axis direction X means the center side of the winding body 30 in the winding axis direction X with reference to an arbitrary position on the winding body 30.

  In other words, the joining portions 31e and 32e of the winding body 30 have the dimension H in the height direction Z from the end side in the winding axis direction X of the winding body 30 toward the center side on the inner surfaces 31g and 32g. It is gradually decreasing. In addition, the dimension H in the height direction Z of the joint portions 31e and 32e of the wound body 30 is maximized at the edge on the end side in the winding axis direction X of the wound body 30, and the wound body 30 is wound. It is minimized at the center side in the axial direction X, that is, at the edge of the negative electrode 32 on the mixture layer 32b side.

  In addition, as for joining part 31e, 32e of the winding body 30, the dimension H of the height direction Z is the winding axis direction of foil exposure part 31c, 32c in at least one of inner surface 31g, 32g and outer surface 31f, 32f. What is necessary is just to gradually reduce toward the mixture layer 31b, 32b side from the edge part side of X. That is, the dimension H in the height direction Z of the joint portions 31e and 32e is the winding of the foil exposed portions 31c and 32c only on one of the inner surfaces 31g and 32g and the outer surfaces 31f and 32f of the joint portions 31e and 32e. You may reduce gradually from the edge part side of the axial direction X toward the mixture layers 31b and 32b side.

  In this case, the shape of one of the inner surfaces 31g and 32g and the outer surfaces 31f and 32f of the joint portions 31e and 32e may be a rectangle including a square, a rectangle, a parallelogram, a rhombus, and the like. Further, in both the inner surfaces 31g, 32g and the outer surfaces 31f, 32f of the joint portions 31e, 32e, the dimension H in the height direction Z of the joint portions 31e, 32e is the winding axis direction X of the foil exposed portions 31c, 32c. It may be gradually decreased from the end portion side toward the mixture layer 31b, 32b side.

  Further, the upper and lower end edges in the height direction Z of the joint portions 31e and 32e of the wound body 30 are separated from the boundary 30c between the flat surface portion 30a and the curved portion 30b of the wound body 30 inside the wound axis direction X. The distance D1 in the height direction Z is the maximum, and the distance D2 in the height direction Z from the boundary 30c is the minimum outside the winding axis direction X. In other words, the upper and lower edges in the height direction Z of the joint portions 31e and 32e of the wound body 30 have the maximum distance D1 from the boundary 30c on the end side in the winding axis direction X of the wound body 30. The distance D2 from the boundary 30c is minimum on the center side in the winding axis direction X of the wound body 30, that is, on the mixture layer 32b side of the negative electrode 32.

  Moreover, as for the junction parts 31e and 32e of the winding body 30, the area of the inner surfaces 31g and 32g and the area of the outer surfaces 31f and 32f may be equal or different. When the areas of the inner surfaces 31g and 32g of the joint portions 31e and 32e are different from the areas of the outer surfaces 31f and 32f, the areas of the inner surfaces 31g and 32g are preferably smaller than the areas of the outer surfaces 31f and 32f. In the prismatic secondary battery 100 of the present embodiment, the joint portions 31e and 32e are trapezoidal with the inner edge in the winding axis direction X as the upper base and the outer edge in the winding axis direction X as the lower base. It is formed into a shape.

  Further, as shown in FIG. 4, the pair of connection pieces 42 of the current collector plate 40 are spaced in the thickness direction Y of the wound body 30 from the inner side to the outer side in the winding axis direction X of the wound body 30. Is provided in a V-shape that gradually expands. And the joining parts 31e and 32e of the wound body 30 joined to the connection piece 42 are inside the thickness direction Y where the inner edge in the winding axis direction X of the wound body 30 is close to the winding axis A. The outer edge in the winding axis direction X is disposed outside the winding axis A in the thickness direction Y. Here, the inner side in the thickness direction Y means the center side of the winding body 30 in the thickness direction Y, that is, the winding axis A side, with an arbitrary position of the winding body 30 as a reference. Further, the outside in the thickness direction Y means an end portion side in the thickness direction Y of the wound body 30 with reference to an arbitrary position of the wound body 30.

  The lid assembly shown in FIG. 2 is configured by joining the current collector plate 40 and the metal plate 50 to the joint portions 31e and 32e of the wound body 30. The wound body 30 constituting the lid assembly is covered with an insulating protective film 61 except for both ends in the winding axis direction X. Further, both ends of the wound body 30 in the winding axis direction X and the pair of current collector plates 40 are covered with a pair of insulating cases 62. The insulating protective film 61 and the insulating case 62 are made of an insulating resin material such as polypropylene, and insulate the wound body 30 and the current collector plate 40 from the battery can 11. The insulating protective film 61 and the insulating case 62 may be provided integrally.

In the lid assembly, the winding body 30 is inserted from the opening of the battery can 11, and the opening of the battery can 11 is closed by the battery lid 12, and the battery lid 12 is opened by, for example, laser welding. Is joined to the battery can 11 by joining over the entire circumference. Thereafter, a non-aqueous electrolyte is injected into the battery container 10 through the liquid injection port 14 of the battery lid 12, and the liquid injection plug 15 is joined to the liquid injection port 14 by, for example, laser welding to seal the battery container 10. As the nonaqueous electrolytic solution to be injected into the battery container 10, for example, a nonaqueous electrolytic solution in which a lithium salt such as lithium hexafluorophosphate (LiPF ₆ ) is dissolved in a carbonate organic solvent such as ethylene carbonate is used. be able to.

  With the above configuration, the prismatic secondary battery 100 is charged by storing the supplied external generated power in the winding body 30 via the external terminal 20 and the current collector plate 40, and the power stored in the winding body 30. Can be supplied to the external device via the current collector plate 40 and the external terminal 20.

  Hereinafter, the operation of the prismatic secondary battery 100 of the present embodiment will be described.

  As described above, the prismatic secondary battery 100 according to the present embodiment includes the flat wound body 30 in which the positive electrode 31 and the negative electrode 32 are wound around the winding axis A. The wound body 30 has foil laminated portions 31d and 32d in which foil exposed portions 31c and 32c of the positive electrode 31 and the negative electrode 32 are laminated on one end and the other end in the winding axis direction X. The foil laminated portions 31 d and 32 d have joint portions 31 e and 32 e that are bundled in two on both sides of the winding axis A in the thickness direction Y of the wound body 30. In addition, the prismatic secondary battery 100 includes a current collector plate 40 joined to the inner surfaces 31g, 32g on the winding axis A side of the joint portions 31e, 32e or the outer surfaces 31f, 32f on the opposite side to the winding axis A. ing.

  Moreover, in the square secondary battery 100 of this embodiment, in order to divide and bundle the foil laminated portions 31d and 32d of the wound body 30, the state before the expansion shown in FIGS. And it is in the expanded state shown in FIG. Thus, in the state where the foil laminated portions 31d and 32d of the wound body 30 are spread, the deformation amount of the foil exposed portions 31c and 32c of the positive electrode 31 and the negative electrode 32 is the winding axis direction of the wound body 30. There is a tendency that the inside of X is large and the outside of the winding body 30 in the winding axis direction X is small.

  Here, the dimension H in the height direction Z of the joint portions 31e and 32e provided in the foil laminated portions 31d and 32d of the winding body 30 is uniform from the outside to the inside in the winding axis direction X of the winding body 30. Or the case of increasing gradually. In this case, the foil exposed portions 31 c and 32 c of the positive electrode 31 and the negative electrode 32 are fixed over a relatively wide range in the height direction Z inside the winding axis direction X of the winding body 30. Then, when the joining portions 31e and 32e are joined to the current collector plate 40 or when vibration is applied to the prismatic secondary battery 100, the positive electrode 31 and the negative electrode are formed inside the winding axis direction X of the winding body 30. A large stress acts on the foil exposed portions 31c and 32c of the electrode 32, and the foil exposed portions 31c and 32c may be cut. The cutting of the foil exposed portions 31c and 32c may lead to the generation of undesirable foreign matter and an increase in electrical resistance.

  Therefore, in the prismatic secondary battery 100 of the present embodiment, as shown in FIGS. 4 and 5, at least one of the inner surfaces 31g and 32g and the outer surfaces 31f and 32f of the joint portions 31e and 32e, the joint portions 31e and 32e. The dimension H in the height direction Z is gradually reduced from the end side in the winding axis direction X of the foil exposed portions 31c and 32c toward the mixture layers 31b and 32b. In other words, the joining portions 31e and 32e of the wound body 30 are wound around the wound body 30 at the end portions on both sides in the height direction Z adjacent to both the curved portions 30b and the height direction Z on the inner surfaces 31g and 32g. The positive electrode 31 and the negative electrode 32 on the side of the mixture layers 31b and 32b at the ends are arranged so as to be separated from the curved portion 30b in the height direction Z rather than the end in the axial direction X ( (See FIG. 3).

  This reduces the range in the height direction Z in which the foil exposed portions 31c, 32c of the positive electrode 31 and the negative electrode 32 are fixed inside the winding axis direction X of the wound body 30, and the foil exposed portions 31c, The stress acting on 32c can be reduced. Therefore, when the joining portions 31e and 32e of the winding body 30 are joined to the current collector plate 40 or when vibration is applied to the prismatic secondary battery 100, the inside of the winding body 30 in the winding axis direction X, The foil exposed portions 31c and 32c of the positive electrode 31 and the negative electrode 32 can be prevented from being cut.

  In addition, the dimension H in the height direction Z of the joining portions 31e and 32e of the wound body 30 gradually decreases from the end side in the winding axis direction X of the foil exposed portions 31c and 32c toward the mixture layers 31b and 32b. By doing so, it becomes maximum outside the winding axis direction X of the winding body 30 and is minimum inside the winding axis direction X of the winding body 30. Accordingly, the dimension H in the height direction Z of the joining portions 31e and 32e is set to the maximum dimension that can be joined to the connection piece 42 of the current collector plate 40 outside the winding axis direction X of the winding body 30. The area of the joint portions 31e and 32e can be increased.

  More specifically, in the prismatic secondary battery 100 of the present embodiment, the joint portions 31e and 32e are arranged on the inner side of the winding axis direction X, that is, on the joint surface, on at least one of the inner surfaces 31g and 32g and the outer surfaces 31f and 32f. It is formed in a trapezoidal shape with the edge on the agent layer 31b, 32b side as the upper bottom and the outer edge in the winding axis direction X, that is, the edge on the edge side of the foil exposed portions 31c, 32c as the lower bottom. Therefore, the area of the joints 31e and 32e can be made larger than that of the conventional elliptical weld as described in Patent Document 2 described above, and the positive electrode 31 and the negative electrode 32 can be gathered together. It becomes possible to further reduce the electric resistance between the electric plate 40 and the electric plate 40.

  In addition, when the areas of the inner surfaces 31g and 32g and the areas of the outer surfaces 31f and 32f are different, for example, the positioning accuracy of the horn and anvil used for ultrasonic welding is used for the joint portions 31e and 32e of the wound body 30. Can be relaxed and the formation of the joint portions 31e and 32e can be facilitated. In this case, it is preferable that the areas of the inner surfaces 31g and 32g of the joint portions 31e and 32e are smaller than the areas of the outer surfaces 31f and 32f. Accordingly, an anvil is disposed adjacent to the outer surfaces 31f and 32f of the large joint portions 31e and 32e, and a horn is disposed adjacent to the inner surfaces 31g and 32g of the small joint portions 31e and 32e. Sonic welding can be performed.

  In the joining portions 31e and 32e of the wound body 30, the current collector plate 40 is joined to the outer surfaces 31f and 32f, and the metal plate 50 is joined to the inner surfaces 31g and 32g. Thereby, in a state where the joining portions 31e and 32e of the wound body 30 are sandwiched between the current collector plate 40 and the metal plate 50, they can be joined by ultrasonic pressure welding, and the positive electrode 31 and the negative electrode 32 can be joined. It is possible to prevent wrinkles from occurring in the exposed foil portions 31c and 32c.

  As described above, according to the prismatic secondary battery 100 of the present embodiment, the foil exposed portions 31c and 32c of the positive electrode 31 and the negative electrode 32 in the wound body 30 in which the positive electrode 31 and the negative electrode 32 are wound. When the foil laminated portions 31d and 32d laminated with are separated into two and joined to the current collector plate 40, an increase in electrical resistance can be suppressed while preventing the foil exposed portions 31c and 32c from being cut.

  In the above-described embodiment, the joint portions 31e and 32e have a trapezoidal shape at least one of the inner surfaces 31g and 32g and the outer surfaces 31f and 32f, and the dimension in the height direction Z of the metal plate 50 is wound. The prismatic secondary battery 100 that is constant in the axial direction X has been described. However, the prismatic secondary battery 100 is not limited to the case where the shapes of the joint portions 31e and 32e are trapezoidal, and the dimension in the height direction Z of the metal plate 50 may not be constant in the winding axis direction X. The metal plate 50 may not be provided. Hereinafter, Modifications 1 to 6 of the prismatic secondary battery 100 of the present embodiment will be described with reference to FIGS. 6 to 11.

  FIG. 6 is a side view of a wound body 30 corresponding to FIG. 5, showing Modification 1 of the prismatic secondary battery 100. In this modification, the joint portions 31e and 32e are formed in a semi-elliptical or semi-oval shape. Thereby, the joining portions 31e and 32e of the wound body 30 are wound on the inner surfaces 31g and 32g by winding the wound body 30 at both ends in the height direction Z adjacent to both the curved portions 30b and the height direction Z. The positive electrode 31 and the negative electrode 32 on the side of the mixture layers 31b and 32b at the ends are arranged so as to be separated from the curved portion 30b in the height direction Z rather than the end in the rotational axis direction X. (See FIG. 3). In other words, the joining portions 31e and 32e are formed such that the outer edge in the winding axis direction X is formed in a straight line along the height direction Z, and the curved portion is directed inward in the winding axis direction X. The dimension H in the height direction Z is gradually decreased from the outside in the winding axis direction X to the inside, that is, from the end side in the winding axis direction X of the foil exposed portions 31c and 32c toward the mixture layers 31b and 32b. doing.

  According to the prismatic secondary battery of the present modification, the area is slightly reduced as compared with the shapes of the joint portions 31e and 32e of the above-described embodiment, but the positive electrode 31 and the negative electrode 32 are arranged inside the winding axis direction X. The range of the height direction Z to which the foil exposed portions 31c and 32c are fixed can be reduced, and the same effect as the prismatic secondary battery 100 of the above-described embodiment can be obtained. Further, corner portions are not formed in the inner portions of the joint portions 31e and 32e in the winding axis direction X, and stress concentration is prevented and the foil exposed portions 31c and 32c of the positive electrode 31 and the negative electrode 32 are cut. Can be effectively prevented.

  FIG. 7 is a side view of a wound body corresponding to FIG. 5, showing a second modification of the prismatic secondary battery 100. In this modification, the joint portions 31e and 32e are formed in a triangular shape. Thereby, the joining portions 31e and 32e of the wound body 30 are wound on the inner surfaces 31g and 32g by winding the wound body 30 at both ends in the height direction Z adjacent to both the curved portions 30b and the height direction Z. The positive electrode 31 and the negative electrode 32 on the side of the mixture layers 31b and 32b at the ends are arranged so as to be separated from the curved portion 30b in the height direction Z rather than the end in the rotational axis direction X. (See FIG. 3).

  In other words, in this modified example, the joint portions 31e and 32e have isosceles sides whose apexes face the inside of the winding axis direction X and whose bases are arranged outside the winding axis direction X along the height direction Z. It is formed in a triangular shape. Thereby, as for the joining parts 31e and 32e, the dimension H of the height direction Z is a mixture layer from the inner side from the outer side of the winding axial direction X, ie, the edge part side of the winding axial direction X of the foil exposure parts 31c and 32c. It gradually decreases toward 31b and 32b. According to the prismatic secondary battery of the present modified example, the area is slightly reduced as compared with the shape of the joint portions 31e and 32e of the modified example 1, but the positive electrode 31 and the negative electrode 32 are arranged inside the winding axis direction X. The range in the height direction Z to which the foil exposed portions 31c and 32c are fixed can be reduced, and the same effect as the prismatic secondary battery 100 of the above-described embodiment can be obtained.

  FIG. 8 is a side view of a wound body corresponding to FIG. 5 and showing a third modification of the prismatic secondary battery 100. In this modification, the joint portions 31e and 32e are formed in a stepped shape. Thereby, the joining portions 31e and 32e of the wound body 30 are wound on the inner surfaces 31g and 32g by winding the wound body 30 at both ends in the height direction Z adjacent to both the curved portions 30b and the height direction Z. The positive electrode 31 and the negative electrode 32 on the side of the mixture layers 31b and 32b at the ends are arranged so as to be separated from the curved portion 30b in the height direction Z rather than the end in the rotational axis direction X. (See FIG. 3).

  More specifically, the joint portions 31e and 32e have a dimension H in the height direction Z from the outside in the winding axis direction X, that is, from the end side in the winding axis direction X of the foil exposed portions 31c and 32c. It decreases in steps from both sides in the height direction Z toward the mixture layers 31b and 32b. In the example shown in FIG. 5, the step in the height direction Z is a single step, but a plurality of steps in the height direction Z may be provided from the outside in the winding axis direction X to the inside. Thereby, the shape of the junction parts 31e and 32e of this modification can be brought close to the shape of the junction parts 31e and 32e of the embodiment and modification example 1. According to the prismatic secondary battery of the present modified example, the area is slightly reduced as compared with the shape of the joint portions 31e and 32e of the modified example 1, but the positive electrode 31 and the negative electrode 32 are arranged inside the winding axis direction X. The range in the height direction Z to which the foil exposed portions 31c and 32c are fixed can be reduced, and the same effect as the prismatic secondary battery 100 of the above-described embodiment can be obtained.

  FIG. 9 is a side view of a wound body corresponding to FIG. 5, showing a fourth modification of the prismatic secondary battery 100. In this modification, the joint portions 31e and 32e are formed in a V shape. Thereby, the joining portions 31e and 32e of the wound body 30 are wound on the inner surfaces 31g and 32g by winding the wound body 30 at both ends in the height direction Z adjacent to both the curved portions 30b and the height direction Z. The positive electrode 31 and the negative electrode 32 on the side of the mixture layers 31b and 32b at the ends are arranged so as to be separated from the curved portion 30b in the height direction Z rather than the end in the rotational axis direction X. (See FIG. 3).

  More specifically, the joint portions 31e and 32e are separated from the trapezoidal joint portions 31e and 32e described in the above-described embodiments at the center in the height direction, and from the inside to the outside in the winding axis direction X, that is, The foil exposed portions 31c and 32c are arranged in a V shape that opens from the end side in the winding axis direction X toward the mixture layers 31b and 32b. In addition, in this modification, although it has shown about the case where the junction parts 31e and 32e are isolate | separated into two in the height direction Z, the junction parts 31e and 32e are isolate | separated into three or more in the height direction Z. May be. According to the prismatic secondary battery of the present modified example, the area is slightly reduced as compared with the shape of the joint portions 31e and 32e of the modified example 1, but the positive electrode 31 and the negative electrode 32 are arranged inside the winding axis direction X. The range in the height direction Z to which the foil exposed portions 31c and 32c are fixed can be reduced, and the same effect as the prismatic secondary battery 100 of the above-described embodiment can be obtained.

  FIG. 10 is a side view of a wound body corresponding to FIG. 5 and showing a fifth modification of the prismatic secondary battery 100. In this modification, the metal plate 50 is formed from the outside in the winding axis direction X to the inside, that is, from the end side in the winding axis direction X of the foil exposed portions 31c and 32c toward the mixture layers 31b and 32b. The dimension H ′ in the vertical direction Z gradually decreases. That is, the metal plate 50 has the dimension H ′ in the height direction Z at the outer edge in the winding axis direction X, and the dimension in the height direction Z at the inner edge in the winding axis direction X. H ′ is minimized. In addition, the prismatic secondary battery of this modification has trapezoidal joint portions 31e and 32e similar to the prismatic secondary battery 100 described in the above embodiment. According to the prismatic secondary battery of this modification, the same effects as those of the prismatic secondary battery 100 of the above-described embodiment can be obtained by the joint portions 31e and 32e. Further, the metal plate 50 reduces the range in the height direction Z in which the foil exposed portions 31c and 32c of the positive electrode 31 and the negative electrode 32 are fixed inside the winding axis direction X, and the positive electrode 31 and the negative electrode 32 Cutting of the foil exposed portions 31c and 32c can be more effectively prevented.

  FIG. 11 is a side view of a wound body corresponding to FIG. 5, showing a sixth modification of the prismatic secondary battery 100. The prismatic secondary battery of the present modification does not have the metal plate 50, but the current collector plate 40 has outer surfaces of the joint portions 31e and 32e of the winding body 30 as in the prismatic secondary battery 100 of the above-described embodiment. It is joined to 31f and 32f. Further, the joining portions 31e and 32e of the wound body 30 are end portions on both sides in the height direction Z adjacent to both the curved portions 30b and the height direction Z in both the inner surfaces 31g and 32g and the outer surfaces 31f and 32f. The positive electrode 31 and the mixture layer 31b, 32b side of the negative electrode 32 at the ends are more in the height direction Z from the curved portion 30b than the end portions in the winding axis direction X of the winding body 30 in FIG. They are arranged apart (see FIG. 3).

  In other words, the joint portions 31e and 32e are such that, in both the inner surfaces 31g and 32g and the outer surfaces 31f and 32f, the dimension H in the height direction Z is from the outer side in the winding axis direction X, that is, the foil exposed portions 31c, It is formed in a trapezoidal shape that gradually decreases from the end side in the winding axis direction 32c toward the mixture layers 31b and 32b. According to the prismatic secondary battery of this modification, the range in the height direction Z in which the foil exposed portions 31c and 32c of the positive electrode 31 and the negative electrode 32 are fixed inside the winding axis direction X is reduced. The same effect as the prismatic secondary battery 100 of the embodiment can be obtained.

[Method for manufacturing rectangular secondary battery]
Hereinafter, an embodiment of a method for manufacturing a prismatic secondary battery according to the present invention will be described with reference to FIGS. The manufacturing method of the rectangular secondary battery 100 of this embodiment mainly includes a winding process, a bundling process, and a joining process.

(Winding process)
In the winding process, as shown in FIG. 3, the separators 33 and 34 are interposed between the positive electrode 31 and the negative electrode 32, and the flat winding is performed around the axis 35 parallel to the winding axis A. A body 30 is produced. The wound body 30 is wound by disposing the foil exposed portion 31c of the positive electrode 31 and the foil exposed portion 32c of the negative electrode 32 at one end and the other end in the winding axis direction X, respectively. Foil laminated portions 31d and 32d in which the foil exposed portions 31c and 32c are laminated at one end and the other end in the direction X are formed.

(Bundling process)
In the bundling step, as shown in FIGS. 4 and 5, the foil laminated portions 31 d and 32 d at the one end and the other end in the winding axis direction X of the wound body 30 are wound in the thickness direction Y of the wound body 30. The shaft A is sandwiched and bundled in two. The prismatic secondary battery 100 of this embodiment has a metal plate 50 fixed to the shaft core 35. Therefore, the foil laminated portions 31d and 32d are divided into two parts by expanding the first portion 51 and the second portion 52 of the metal plate 50 so as to spread in the thickness direction Y of the wound body 30. Can do.

(Joining process)
In the joining step, the foil exposed portions 31c and 32c that are bundled in two, that is, the foil laminated portions 31d and 32d, are joined by ultrasonic pressure welding to form the joined portions 31e and 32e, and the joined portions 31e and 32e. The current collector plate 40 is joined to the inner surfaces 31g, 32g or the outer surfaces 31f, 32f.

  FIG. 12 is an explanatory diagram of a method for manufacturing the prismatic secondary battery 100 of the present embodiment. 12, (a) is a plan view of the inner surfaces 31g and 32g of the joint portions 31e and 32e, (b) is a plan view of the outer surfaces 31f and 32f of the joint portions 31e and 32e, and (c) is a horn. 200 is a side view of the anvil 300. FIG.

  In the manufacturing method of the prismatic secondary battery 100 of the present embodiment, in the joining step, the joining portions 31e and 32e are arranged in the winding axis direction of the winding body 30 on at least one of the inner surfaces 31g and 32g and the outer surfaces 31f and 32f. The dimension in the height direction Z perpendicular to X and the thickness direction Y is such that the mixture layer 31b from the outside in the winding axis direction X, that is, from the end side in the winding axis direction X of the foil exposed portions 31c and 32c, It is formed in a shape that gradually decreases toward the 32b side.

  Specifically, in the example shown in FIG. 12, the joint portions 31e and 32e are such that the inner surface 31g and 32g has a dimension H in the height direction Z from the outside in the winding axis direction X, that is, the foil exposed portion 31c. , 32c is formed in a trapezoidal shape that gradually decreases from the end portion side in the winding axis direction X toward the mixture layer 31b, 32b side. On the other hand, the joint portions 31e and 32e are formed in a rectangular shape having long sides parallel to the height direction Z on the outer surfaces 31f and 32f.

  In the joining step, the anvil 300 is disposed adjacent to the outer surface on the opposite side of the winding axis A of the foil exposed portions 31c and 32c bundled in two, that is, the foil laminated portions 31d and 32d, and the winding axis A A horn 200 is placed adjacent to the inner surface of the side. A plurality of convex portions 201 may be formed on the surface of the horn 200 facing the foil laminated portions 31d and 32d. Moreover, you may form the some convex part 301 in the surface which opposes the foil lamination | stacking parts 31d and 32d of the anvil 300. FIG. The shape of the protrusions 201 and 301 is not particularly limited, and for example, a shape such as a quadrangular prism, a cylinder, a triangular prism, a cone, or a triangular pyramid can be used.

  The foil laminates 31d and 32d are sandwiched between the current collector plate 40 and the metal plate 50, and the joining portions 31e and 32e are joined to the foil laminates 31d and 32d by ultrasonic pressure welding using the horn 200 and the anvil 300. Then, the joining portions 31 e and 32 e are joined to the current collector plate 40 and the metal plate 50. By forming the convex portions 201 and 301 on the horn 200 and the anvil 300, the frictional force acting between the current collector plate 40 and the metal plate 50 in contact with the horn 200 and the anvil 300 is increased, so that the ultrasonic pressure welding is effective. Can be done. Even when the metal plate 50 is not provided, similarly, the frictional force acting between the horn 200 and the anvil 300, the current collector plate 40 and the foil laminated portions 31d and 32d is increased, and the ultrasonic pressure welding is effectively performed. Can be done.

  Here, the area of the surface of the anvil 300 facing the foil stacking portions 31d and 32d is larger than the area of the surface of the horn 200 facing the foil stacking portions 31d and 32d. Therefore, in the joint portions 31e and 32e, the areas of the outer surfaces 31f and 32f arranged adjacent to the anvil 300 are larger than the areas of the inner surfaces 31g and 32g arranged adjacent to the horn 200. Thereby, the positioning accuracy of the horn 200 and the anvil 300 can be relaxed, and ultrasonic pressure welding can be facilitated. Further, the horn 200 is disposed adjacent to the inner surfaces 31g and 32g of the joint portions 31e and 32e, so that the anvil 300 is disposed adjacent to the inner surfaces 31g and 32g of the joint portions 31e and 32e. Ultrasonic pressure welding can be facilitated.

  According to the method for manufacturing the prismatic secondary battery 100 of the present embodiment, the joints 31e and 32e of the wound body 30 are dimensioned in the height direction Z on at least one of the inner surfaces 31g and 32g and the outer surfaces 31f and 32f. H can be formed in a shape that gradually decreases from the outer side in the winding axis direction X, that is, from the end side in the winding axis direction X of the foil exposed portions 31c and 32c toward the mixture layers 31b and 32b. . Therefore, in the wound body 30 in which the positive electrode 31 and the negative electrode 32 are wound, the portion where the foil exposed portions 31c and 32c of the positive electrode 31 and the negative electrode 32 are laminated is divided into two and joined to the current collector plate 40. When the vibration is applied to the prismatic secondary battery 100, an increase in electrical resistance can be suppressed while preventing the foil exposed portions 31c and 32c from being cut.

  In the method for manufacturing the prismatic secondary battery 100 according to the present embodiment, the anvil 300 is disposed adjacent to the outer surface of the foil laminated portion 31d, 32d of the wound body 30 on the side opposite to the winding axis A, and the wound body 30 is wound. The example which arrange | positions the horn 200 adjacent to the inner surface by the side of the axis | shaft A was demonstrated. However, it is also possible to arrange the horn 200 adjacent to the outer surface of the foil laminates 31d and 32d and arrange the anvil 300 adjacent to the inner surface of the foil laminates 31d and 32d. In this case, in the joint portions 31e and 32e, the areas of the inner surfaces 31g and 32g disposed adjacent to the anvil 300 are larger than the areas of the outer surfaces 31f and 32f disposed adjacent to the horn 200.

  The embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

30 Winding body, 31 Positive electrode (electrode), 31b Positive electrode mixture layer (mixture layer), 31c Foil exposed portion, 31e Joint portion, 31f Outer surface, 31g Inner surface, 32 Negative electrode (electrode), 32b Negative electrode composite Agent layer (mixture layer), 32c Foil exposed portion, 32e Joint portion, 32f Outer surface, 32g Inner surface, 40 Current collector plate, 40A Positive electrode current collector plate, 40B Negative electrode current collector plate, 50 Metal plate, 100 Square secondary Battery, 200 Horn, 300 Anvil, A Winding axis, H Joint height dimension, H 'Metal plate height dimension, X Winding axis direction, Y Thickness direction, Z Height direction

Claims (7)

A flat wound body in which the electrode is wound around the winding axis, and the foil exposed portion of the electrode laminated at one end and the other end in the winding axis direction of the wound body is the thickness of the wound body. A prismatic secondary battery comprising a joint part that is bundled in two on both sides of the winding shaft in a direction,
The wound body has a curved portion in which the electrodes are curved and stacked on both sides in the height direction perpendicular to the winding axis direction and the thickness direction,
The joining portion includes the winding body at an end portion adjacent to at least one of the curved portion and the height direction on at least one of the inner surface on the winding shaft side and the outer surface on the opposite side to the winding shaft. The electrode mixture layer side of the electrode at the end is arranged so as to be separated from the curved portion in the height direction, rather than the end side in the winding axis direction .
In the prismatic secondary battery, the area of the inner surface and the area of the outer surface of the joint are different . The junction area of the inner surface, prismatic secondary battery according to claim 1, characterized in that less than the area of said outer surface. The prismatic secondary battery according to claim 2 , wherein a current collector plate is bonded to the outer surface and a metal plate is bonded to the inner surface of the bonding portion. 4. The prismatic secondary battery according to claim 3 , wherein the metal plate has a dimension in the height direction that gradually decreases from the outside toward the inside in the winding axis direction. The shape of the inner surface of the joint portion is trapezoidal, triangular, semicircular, semielliptical, semielliptical, V-shaped, or stepped, or any one of claims 1 to 4 A prismatic secondary battery according to claim 1. The shape of the said outer surface of the said junction part is a rectangle, trapezoid, a triangle, a semicircle, a semi-ellipse, a semi-oval, or a staircase shape, The any one of Claims 1-4 characterized by the above-mentioned. The prismatic secondary battery according to one item. A winding step of winding the electrode around the winding axis to produce a flat wound body, and a foil exposed portion of the electrode laminated on one end and the other end of the winding body in the winding axis direction. In the thickness direction of the wound body, a bundling step in which the winding shaft is sandwiched and bundled in two, and the foil exposed portions that have been bundled in two are joined by ultrasonic pressure welding to form a joint portion. A method of manufacturing a prismatic secondary battery comprising a joining step,
In the joining step, the joining portion has a height direction perpendicular to the winding axis direction and the thickness direction on at least one of the inner surface on the winding axis side and the outer surface on the opposite side to the winding axis. Is formed in a shape that gradually decreases toward the mixture layer side of the electrode ,
In the joining step, an anvil is arranged adjacent to one surface of the bundle exposed foil exposed portion on the winding shaft side or the outer surface on the opposite side of the winding shaft, and on the other surface. place the horn by adjacent, characterized that you form the joint is larger than the area of the surface area of the surface that is positioned adjacent disposed adjacent to the horn to the anvil prismatic secondary A method for manufacturing a secondary battery.

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