JP2012252980A - Square battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a square battery having a wound electrode body which can prevent a metal foil exposed part from interfering with a winding core when the metal foil exposed part is deformed.SOLUTION: A square battery comprises a flat wound electrode body 120 in which a belt-like electrode is wound around a plate-like winding core 126. The winding core 126 is formed of a rectangular plate, and has a taper part 126b with a narrower plate width formed at four corners. Electrodes 122 and 124 comprise a belt-like metal foil, a coated part in which the metal foil is coated with an active material mixture, and metal foil exposed parts 122A and 124A in which the metal foil is not coated with the active material mixture along one long side of the metal foil, and in the winding core 126, the coated part is arranged in a wound axial center part 126A while the metal foil exposed parts 122A and 124A are arranged in wound axial ends 126B and 126B.

Description

  The present invention relates to a prismatic battery including a flat wound electrode body in which a strip-shaped electrode is wound around a plate-shaped winding core.

  Conventionally, a prismatic battery is known as a battery capable of obtaining a higher volume density than a cylindrical battery. In the rectangular battery, a flat wound electrode body in which a cross-section formed by spirally winding a separator between a belt-like positive electrode and a negative electrode via a separator is formed in a rectangular battery case is housed. At the same time, an electrolytic solution is injected.

  The prismatic battery has a positive electrode and a negative electrode metal foil exposed portion projecting from both ends in the winding axis direction of the wound electrode body, and an electrode terminal or a current collector is connected to the metal foil exposed portion. By reducing the connection resistance, the output is reduced. Such a configuration is also effective for downsizing.

  Regarding the connection form between the winding body and the current collector, for example, a power storage element of Patent Document 1 has been proposed. In the electric storage element described in Patent Document 1, after winding the electrode to form a wound electrode body, the metal foil exposed portion of the electrode stacked at the axial end of the wound electrode body is deformed, Dividing into two parts in the thickness direction with the winding center of the electrode body as a boundary, and forming each of them together in the thickness direction to form a pair, and a pair of oppositely gathered parts gathered in the two parts The sheet connecting part of the current collecting terminal is inserted between the parts and ultrasonically joined to the gathering part.

  Conventionally, a method of manufacturing a flat wound electrode body by winding an electrode around a plate-shaped winding core has been proposed (Patent Document 2).

JP 2003-249423 A JP 2011-71052 A

  However, in the wound electrode body having a plate-shaped winding core, when the metal foil exposed portion is deformed to form a pair of gathering portions as shown in Patent Document 1, the winding core of the metal foil exposed portion is deformed. The curved portions formed by bending at both ends in the winding width direction are pulled in a direction approaching the core and interfere with the core. Therefore, unnecessary tension is generated between the exposed portion of the metal foil and the core, and the exposed portion of the metal foil may be damaged by the tension.

  The present invention has been made in view of the above points, and the object of the present invention is to provide a metal foil when the exposed portion of the metal foil of a wound electrode body in which an electrode is wound around a winding core is deformed. An object of the present invention is to provide a prismatic battery having a wound electrode body that can prevent the exposed portion from interfering with the core and stabilize the quality.

  In order to achieve the above object, a prismatic battery according to the present invention is a prismatic battery including a flat wound electrode body in which a strip-shaped electrode is wound around a plate-shaped core, and the core is a core. The winding axis direction end portion has a shape with a narrower plate width in the direction perpendicular to the winding axis direction of the winding core than the winding axis direction center portion. The winding core is formed in a rectangular shape, and taper portions and step portions are formed at the four corners to narrow the plate width.

  According to the rectangular battery of the present invention, when the metal foil exposed portion of the wound electrode body is deformed, the metal foil exposed portion can be prevented from interfering with the winding core. Therefore, the quality when the metal foil exposed portion is divided and welded with the core specification can be improved. Accordingly, it is possible to prevent the battery performance from deteriorating due to electrode breakage, internal short circuit or non-uniformity of the electrode tension, and to improve the performance of the rectangular battery including the flat wound electrode body. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

The perspective view which shows the external appearance of 1st Embodiment of the square battery which concerns on this invention. The exploded perspective view of the square battery of FIG. (A) is a perspective view of the cover assembly of the square battery of FIG. 1, (b) is sectional drawing which follows the bb line which shows the shape of a current collecting plate. The disassembled perspective view of the winding electrode body in the square battery of FIG. (A) is a front view of the winding core in the square battery of FIG. 1, (b) is a perspective view showing a wound electrode body including the winding core. The principal part enlarged view which shows a winding electrode body lamination | stacking part and a core width change position. It is a figure explaining the connection process of a current collecting plate and a winding electrode body, (a) is sectional drawing of the state which inserted the electrode foil laminated part in the current collecting plate, (b) is the state which extended the electrode foil laminated part FIG. The perspective view which shows the winding electrode body end surface expanded by the expansion member. It is a figure explaining the condition which ultrasonically welds a winding electrode body with a current collecting plate, (a) is explanatory drawing of the state which pinched the current collection foil and the connection board with the ultrasonic welding machine, (b) is welding. The principal part sectional drawing after. The perspective view which fixed the negative electrode current collecting plate to the winding electrode body, and was seen from the negative electrode end surface. The 2nd Embodiment of the square battery by this invention is shown, (a) is a front view of a winding core, (b) is a perspective view of the winding electrode body containing a winding core.

  An embodiment in which a rectangular battery according to the present invention is applied to a lithium ion secondary battery will be described with reference to the drawings. It should be noted that the scales and aspect ratios of the drawings do not match for convenience of drawing, and the shapes and dimensions of the parts are the same in the drawings.

[Configuration of square battery]
As shown in FIGS. 1 and 2, the lithium ion secondary battery BC includes a container 10 having an opening at one end, and a power storage element assembly 11 accommodated in the container 10. The opening of the container 10 is sealed with a lid 111. The lid 111 is provided with a positive external terminal 113 and a negative external terminal 114.

[Storage element assembly]
As shown in FIG. 2, the power storage element assembly 11 includes a lid assembly 110 and a wound electrode body 120. The positive electrode current collector plate 115 and the negative electrode current collector plate 116 of the lid assembly 110 are integrated by welding the positive electrode metal exposed portion and the negative electrode metal exposed portion of the wound electrode body 120 by ultrasonic welding or the like.

[Lid assembly]
As shown in FIG. 3, the lid assembly 110 includes a lid 111 that closes the opening of the container 10, a positive external terminal 113 and a negative external terminal 114 that protrude from the lid 111 through an insulating seal member 112, and these external terminals. A positive current collector 115 and a negative current collector 116 connected to 113 and 114, respectively. The positive and negative external terminals 113 and 114 are fixed to the lid 111 in a state of being electrically insulated from the lid 111 by the insulating seal member 112. The lid 111 is provided with a gas discharge port 111B and a liquid injection port 111C that is an injection port for an electrolyte. The injection port 111C is sealed with an injection plug 111A after the injection.

  The positive electrode current collector 115 extends along the positive electrode side end surface of the wound electrode body 120 from the lid 111 in the container bottom direction, and further bifurcates from the lower end side surfaces of the base 115A and further extends in the container bottom direction. A pair of positive electrode connection pieces 115B. As shown in FIG. 3B, the pair of connection pieces 115 </ b> B are inclined so that the distance between the connection pieces becomes narrower toward the tip as viewed from above the container 10. The pair of inner surfaces 115C of the pair of connection pieces 115B are welded to the outer surface of the positive electrode metal foil exposed portion 122A (see FIG. 4) of the wound electrode body 120 as described later.

  Similarly, the negative electrode current collector plate 116 includes a base portion 116A extending in the container bottom direction from the lid 111 along the negative electrode side end surface of the wound electrode body 120, and bifurcating from both side surfaces of the lower end of the base portion 116A. A pair of negative electrode connection pieces 116B extending in the direction is provided. Similarly to the connection piece 115B, the pair of connection pieces 116B are inclined so that the distance between the connection pieces becomes narrower as the tip is approached, as viewed from above the container 10. The pair of inner surfaces 116C of the pair of connection pieces 116B are welded to the outer surface of the negative electrode metal foil exposed portion 124A (see FIG. 4) of the wound electrode body 120, as will be described later.

  The pair of positive electrode connection pieces 115B is connected to the positive electrode metal foil exposed portion 122A on one end side of the wound electrode body 120, and the pair of negative electrode connection pieces 116B is connected to the negative electrode metal foil exposed portion on the other end side of the wound electrode body 120. Connected to 124A, the wound electrode body 120 is sandwiched from both sides of the winding axis direction.

[Winded electrode body]
As shown in FIG. 4, the wound electrode body 120 is configured by winding a positive electrode 122 and a negative electrode 124 around a winding core 126 shown in FIG. 5 in a flat shape with a separator 121 interposed therebetween. The positive electrode 122 has a strip-shaped positive metal foil made of an aluminum foil or an aluminum alloy foil, and the negative electrode 124 has a strip-shaped negative metal foil made of a copper foil or a copper alloy foil. The separator 121 is a porous polyethylene resin.

  A positive electrode active material mixture is applied to both surfaces of the positive electrode metal foil of the positive electrode 122 to form a positive electrode mixture layer (positive electrode mixture application portion) 123. A negative electrode active material mixture is coated on both surfaces of the negative electrode metal foil of the negative electrode 124 to form a negative electrode mixture layer (negative electrode mixture coating portion) 125. The positive electrode 122 is not coated with the positive electrode active material mixture along one long side of the positive electrode metal foil, and the uncoated positive electrode metal foil exposed portion (uncoated) where the positive electrode metal foil is exposed. 122A) is also provided. The negative electrode 124 is not coated with the negative electrode active material mixture along the other long side opposite to the positive electrode metal foil, and the uncoated negative electrode metal foil exposed portion where the negative electrode metal foil is exposed ( 124A) (also referred to as an uncoated portion).

  The positive electrode 122 and the negative electrode 124 are formed such that the length of the negative electrode mixture layer 125 in the winding axis direction is longer than the length of the positive electrode mixture layer 123 in the winding axis direction. In the positive electrode 122, the winding axis direction both side end positions of the positive electrode mixture layer 123 are in the winding axis direction more than the boundary position between the winding axis direction central portion 126A and the winding axis direction end portion 126B of the winding core 126 described later. It is wound around the core 126 so as to be arranged at the center position. Further, the negative electrode 124 has a winding core 126 such that the both end positions in the winding axis direction of the negative electrode mixture layer 125 are arranged at positions outside the both ends in the winding axis direction of the positive electrode mixture layer 123. Be beaten by.

  The positive electrode 122 and the negative electrode 124 are wound around the winding core 126 so that the positive electrode metal foil exposed portion 122A is disposed on one side in the winding axis direction and the negative electrode metal foil exposed portion 124A is disposed on the other side in the winding axis direction. The The positive electrode metal foil exposed portion 122A and the negative electrode metal foil exposed portion 124A are connected to the positive electrode current collector plate 115 and the negative electrode current collector plate 116, respectively.

[Core]
Next, the configuration of the core 126 will be described with reference to FIGS. In order to facilitate understanding of the description, as shown in FIG. 5, the winding axis direction of the core 126 is the X direction, the direction perpendicular to the plane of the core 126 is the Z direction, and the X of the core 126 is X. The direction orthogonal to the direction and the Z direction will be described as the Y direction.

  The winding core 126 is a rectangular plate-shaped member corresponding to the planar shape of the wound electrode body 120 using polypropylene resin as a material, and corresponds to the portion where the positive electrode mixture layer 123 and the negative electrode mixture layer 125 are applied. A central portion 126A and end portions 126B corresponding to the metal foil exposed portions 122A and 124A, which are located on both sides of the central portion 126A and are not coated with an active material, are provided.

  The winding core 126 has a shape in which the end portion 126B is narrower in the Y direction than the center portion 126A. For example, the winding core 126 is formed by forming tapered portions 126b at four corners of a rectangular plate member. The width is narrowed.

  The central portion 126A of the winding core 126 has a pair of parallel outer edge portions 126a and 126a extending along the X direction. The end portion 126B of the core 126 has a side end surface with a plate width V2 that is narrower than the plate width V1 of the outer edge portions 126a and 126a. In the core 126, the positive electrode mixture layer 123 and the negative electrode mixture layer 125 of the positive electrode 122 and the negative electrode 124 are disposed in the central portion 126A, and the metal foil exposed portions 122A and 124A are disposed in the end portions 126B and 126B. And on the core 126, the positive electrode mixture layer 123 and the negative electrode mixture layer 125 are arranged with the separator 121 interposed therebetween, and the positive electrode metal foil exposed portion is disposed at the end 126B on one side in the X direction of the core 126. 122A is arranged, and is wound in a state where the negative electrode metal foil exposed part 124A is arranged at the other end 126B.

  The end 126B of the core 126 is formed so that the plate width in the Y direction becomes narrower as it moves in the direction away from the central portion 126A along the X direction. Further, a negative electrode expansion operation plate (negative electrode expansion member) 90N is attached to the negative electrode side end surface of the winding core 126 in the X direction, and a positive electrode expansion operation plate (positive electrode expansion member) is attached to the positive electrode side end surface. 90P is installed. And the protruding piece 93 which one part protruded from the both ends of the winding core 126 rather than the both ends of the winding electrode body is provided.

  That is, as shown in detail in FIG. 6, the winding core 126 has tapered portions 126b at the four corners of the rectangular winding core 126, and the plate width of the winding core 126 is narrower than the plate width of the central portion 126A. It has become. Further, the winding core 126 has tapered portions 126b formed at the four corners so that the lateral width (winding axis direction length) H1 along the X direction of the central portion 126A is equal to the lateral width of the positive electrode mixture layer 123 of the positive electrode 122 (捲The rotational axis length) is set larger than H2. The lateral width H1 of the central portion 126A and the lateral width of the negative electrode mixture layer 125 of the negative electrode 124 are set to coincide. With this configuration, ions are efficiently transferred during charging / discharging between the positive foil 122 and the negative foil 124.

  At both ends of the winding core 126 in the winding axis direction, concave portions 126c to which the positive and negative electrode expanding operation plates 90P and 90N are attached are formed by notching, and a slit 126d is formed at the core end surface of the concave portion 126c. Is provided. The recess 126c has a rectangular shape with a size to accommodate the expansion operation plates 90P and 90N. The size of the recess 126c in the X direction is substantially the same as the size of the side portion 126B, and the size of the recess 126c in the Y direction is set slightly larger than the expansion operation plates 90P and 90N.

  The base portion of the positive-side expansion operation plate 90P is inserted and fixed in the slit 126d so that the pair of blades 91 are expanded. As shown in FIG. 5, the pair of thin metal plates (blades) 91 are provided with operation protrusions 91A and 91B. The operation protrusions 91 </ b> A and 91 </ b> B protrude from the flat end surface of one end of the wound electrode body 120. The negative side expansion operation plate 90N has the same configuration, and is inserted and fixed in a slit 126d formed in the recess 126c so that the pair of blades 92 can be expanded, and the operation protrusions 92A and 92B are provided. The wound electrode body 120 protrudes from a flat end surface at one end. The core 126 is formed of an insulating material, and in particular, at least one resin material of PP (polypropylene) resin, PBT (polybutylene terephthalate) resin, PPS (polyphenylene sulfide) resin, or PEEK (polyether ether ketone) resin is used. It is formed using.

  As shown in FIG. 7, the negative electrode side expansion operation plate 90 </ b> N grasps the operation protrusions 92 </ b> A and 92 </ b> B to expand the metal thin plates 92 and 92, thereby exposing the metal foil on the flat end surface of the wound electrode body 120. The foil laminated portion of the portion 124A (122A) is expanded outward in the thickness direction of the wound electrode body 120 so that a V-shaped opening 120V continuous to the innermost periphery of the wound electrode body 120 is formed. It is configured.

The metal thin plates 91 and 92 constituting the positive electrode expanding operation plate 90P and the negative electrode expanding operation plate 90N are welded and electrically connected to the metal foil exposed portions 122A and 124A of the wound electrode body 120 (divided welding). . Therefore, it is preferable to manufacture the thin metal plates 91 and 92 with a material having the same polarity as the positive electrode 122 and the negative electrode 124. Specifically, the positive metal thin plate 91 is formed of an aluminum foil or an aluminum alloy foil, and the negative metal thin plate 92 is formed of a copper foil or a copper alloy foil. As described above, the lithium ion secondary battery BC includes the flat wound electrode body 120 in which the positive electrode 122 and the negative electrode 124 are wound as the band-shaped electrodes on the plate-shaped core 126.
The manufacturing process of the above square battery BC will be described.

[Assembly of prismatic secondary battery]
The lid assembly 110 and the wound electrode body 120 are integrated to produce the electricity storage element assembly 11 shown in FIG. 2, and the electricity storage element assembly 11 is inserted into the container 10. The lid 111 is laser welded to the container 10 to seal the opening of the container 10, and then an electrolytic solution (not shown) is injected into the container 10 from the liquid injection port 111 </ b> C. After injecting the electrolyte, the injection port 111C is sealed with an injection plug 111A and laser welded. A gasket 112 made of an insulating resin is attached to the positive external terminal 113 and the negative external terminal 114, and is electrically insulated from the lid 111. At the same time, between the positive external terminal 113 and the negative external terminal 114 and the lid 111, Sealed water has been made. The gas discharge port 111B is provided with a cleavage valve (not shown), which is broken when the internal pressure of the container 10 rises and discharges the internal gas to the outside of the container 10.

[Assembly of storage element assembly]
The assembly procedure of the electricity storage element assembly 11 will be described.
First, the wound electrode body 120 shown in FIG. 4 is created. That is, around the core 126 shown in FIGS. 5 and 6, the separator 121 is wound one or more times, and the positive electrode 122 and the negative electrode 124 are stacked while being insulated by the separator 121. At that time, as shown in FIG. 6, in the core 126 for the positive electrode 122, the end portion in the X direction of the center portion 126 </ b> A is positioned at least on the outer side in the X direction than the side end portion of the positive electrode mixture layer 123. In FIG. 6, the negative electrode mixture layer 125 is formed wider than the positive electrode mixture layer 123, and the horizontal width position of the negative electrode mixture layer 125 and the horizontal width position of the central portion 126A are in the stacking thickness direction. Has been wound up to match.

  The separator 121 on the outermost surface of the wound electrode body 120 is locked with a tape (not shown). As shown in FIG. 4, the winding is performed by using protrusions 93 protruding from both end faces of the wound electrode body 120. Therefore, it is not necessary to set the spindle of the winding machine on the inner side in the width direction of the winding electrode body 120 at the time of winding, and the step in the thickness direction of the spindle and the winding core has an adverse effect on winding or is removed from the spindle after winding. At this time, the spindle is not brought into contact with the exposed portion of the metal foil and damaged, and the productivity can be easily improved.

  Prior to integrating the wound electrode body 120 and the current collector plates 115 and 116, the metal foil exposed portions 122A and 124A of the wound electrode body 120 are crushed and deformed in the thickness direction (Z direction). That is, the thickness of the exposed portion of the metal foil is compressed and thinned. The inner surface 115C of the pair of bifurcated connection pieces 115B of the positive electrode current collector plate 115 is opposed to the outer surface of the positive electrode metal foil exposed portion (connection portion) 122A of the wound electrode body 120, and the negative electrode metal foil is exposed. Between the pair of connection pieces 115B of the positive electrode current collector plate 115 so that the inner surface 116C of the pair of bifurcated negative electrode connection pieces 116B of the negative electrode current collector plate 116 faces the outer surface of the portion (connection part) 124A. The wound electrode body 120 is inserted between the pair of connection pieces 116 </ b> B of the current collector plate 116. This state is shown in FIG. 7A, which is a cross-sectional view of the negative electrode end portion of the square secondary battery BC.

  The positive electrode current collector plate 115 is made of aluminum. Moreover, the metal foil which comprises the positive electrode 122 is an aluminum foil, and the foil laminated body 122C of the positive electrode metal foil exposed part is formed in many layers in the wound electrode body 120. The negative electrode current collector plate 116 is made of copper. Moreover, the metal foil which comprises the negative electrode 124 is a copper foil, and the foil laminated body 124C of the negative electrode metal foil exposed part is formed in many layers in the wound electrode body 120.

  After inserting the wound electrode body 120 between the current collecting plates 115 and 116, as shown in FIG. 7B, the pair of blades 92 of the expansion operation plate 90N (90P) are moved to the operation protrusions 92A and 92B. To open the foil laminated body 124C of the negative electrode connecting portion 124A from the inner peripheral side to the outer side at the end face of the wound electrode body 120, and as shown in FIG. 8, the end face of the wound electrode body 120 is also opened. The foil laminate 124C is expanded in a V shape to form a V-shaped opening 120V.

  When the foil laminate is expanded in a V shape, the foil laminate 124C (122C) of the metal foil exposed portion 124A (122A) is pushed outward in the thickness direction of the wound electrode body 120 (D1 direction), 2 By being divided into two, the end surface curved portion of the metal foil exposed portion 124A (122A) in the direction perpendicular to the thickness of the wound electrode body 120 is displaced inward (D2 direction).

  Here, in the core 126 in the present embodiment, since the plate width of the end portion 126B is narrower than the central portion 126A by the tapered portion 126b, the metal foil exposed portion 124A (122A) is on the inner side (D2 direction). Even if it is displaced, there is no contact. Therefore, the metal foil exposed portion 124A (122A) does not interfere with the core 126 and tension is not generated, and the foil laminate can be prevented from being broken, and the foil laminate of the metal foil exposed portion 124A (122A) can be easily obtained. It is possible to divide 124C into two by pushing it outward in the thickness direction of the wound electrode body 120. The same applies to the end face of the positive electrode connecting portion 122A.

  After the foil laminates 122C and 124C at the exposed portions of the metal foil located on both end faces of the wound electrode body 120 are pushed outward by the expansion operation plates 90P and 90N and divided into two foil laminates, respectively, FIG. As shown in FIG. 4, the negative electrode current collector (metal foil exposed portion) is formed between the bifurcated negative electrode connecting plate 116B and the thin metal plate 92 by the ultrasonic bonding transducer WH (horn) and the stator WA (anvil). ) 124A foil laminate 124C is sandwiched. Although illustration is omitted, similarly, the foil laminate 122C of the negative electrode current collector (metal foil exposed portion) 122A is sandwiched between the bifurcated positive electrode connection plate 115B and the metal thin plate 91. The metal foil exposed portion laminate 124C is sandwiched between the bonding surface 116C of the negative electrode connection piece 116B and the negative electrode blade 92, and ultrasonic bonding is performed. The positive electrode side is similarly joined. Accordingly, the wound electrode body 120 is electrically connected to the positive electrode current collector plate 115 and the negative electrode current collector plate 116.

  The positive electrode metal foil exposed portion 122A and the negative electrode metal foil exposed portion 124A are directly welded to the positive electrode connecting piece 115B and the negative electrode connecting piece 116B, for example, at two locations in the circumferential direction. , 116 can be shortened, the connection resistance can be reduced, and the output of the battery can be increased.

  As a result of the above assembly procedure, as shown in FIG. Connected and integrated by welding. Although not shown, the positive electrode metal foil exposed portion (connection portion) 122A exposed on the other side end face of the wound electrode body 120 is welded to the metal thin plate 91 and the connection piece 115B of the positive electrode current collector plate 115. Connected and integrated.

  The manufacturing process described above includes a step of forming a flat wound electrode body 120 in which a positive electrode 122 and a negative electrode 124 are wound on a plate-shaped core 126 via a separator 121, and winding of the wound electrode body 120. The foil laminates 122C and 124C of the positive electrode metal foil exposed portion (connecting portion) 122A and the negative electrode metal foil exposed portion (connecting portion) 124A that are not coated with the active material of the positive electrode sheet and the negative electrode sheet, located on both end surfaces in the axial direction. A step of providing expanding members 90N and 90P for expanding the foil laminate from the inside to the outside on the inside, and expanding the expanding member to expose the positive electrode metal foil exposed portion and the negative electrode metal foil exposed portion of the wound electrode body 120 The foil laminate is spread from the inside to the outside and divided into two foil laminates, and the two divided foil laminates are connected to the positive current collector 115 and the negative current collector 116. .

  The prismatic lithium ion secondary battery BC according to the first embodiment described above can provide the following operational effects.

  (1) Spreading operation plates 90P and 90N are provided at the winding center portions of the foil laminates 122C and 124C of the metal foil exposed portions 122A and 124A located at both ends in the winding axis direction of the wound electrode body 120, and the spreading operation is performed. When the foil laminates 122C and 124C are pushed open from the inside by the opening operation of the plates 90P and 90N, the foil laminates 122C and 124C of the metal foil exposed portions 122A and 124A are pushed outward in the thickness direction of the wound electrode body 120. As a result, the curved end surfaces of the metal foil exposed portions 122A and 124A in the direction perpendicular to the thickness of the wound electrode body 120 are displaced inward.

  However, the winding core 126 in the present embodiment is provided with a tapered portion 126b at the end 126B in contact with the metal foil exposed portions 122A and 124A, and the plate width (V2) in the direction orthogonal to the winding axis direction is narrow. Due to the shape, the metal foil exposed portions 122A and 124A are not in contact with each other even if they are displaced inward, that is, deformed toward the center in the plate surface direction. Therefore, the foil laminates 122C and 124C of the metal foil exposed portions 122A and 124A are easily pushed outward in the thickness direction of the wound electrode body 120 without the metal foil exposed portions 122A and 124A being stretched or broken. be able to. Therefore, the foil laminates 122C and 124C that are likely to be deformed and damaged can be easily expanded, and the positive electrode metal foil exposed portion 122A and the negative electrode metal foil exposed portion 124A can be connected to the positive electrode current collector without damaging the positive electrode 122 and the negative electrode 124. It can be connected to the plate 115 and the negative electrode current collector plate 116.

  (2) Further, at the winding center part of the foil laminates 122C and 124C wound in a multi-oval shape at both ends of the wound electrode body 120, an expansion operation plate 90P provided on the innermost periphery or inside thereof. , 90N, as described above, the core 126 is provided with the tapered portion 126b and escapes from the portion in contact with the metal foil exposed portions 122A, 124A, so that the metal foil exposed portions 122A, 124A are on the inner side. Even if it is displaced, there is no interference. Therefore, the metal foil exposed portions 122A and 124A are not broken, and the foil laminated portions of the metal foil exposed portions 122A and 124A can be easily expanded outward in the thickness direction of the wound electrode body 120. The electrode foil at the exposed portion of the metal foil that is easily bent or deformed can be easily and reliably bundled and bonded to the bonding surfaces 115C and 116C of the current collector plates 115 and 116. As a result, the exposed metal foil portion can be joined to the joining surface of the current collector plate with high work efficiency, and the productivity can be increased and the cost can be reduced.

[Second Embodiment]
Next, a second embodiment in which the prismatic secondary battery according to the present invention is applied to a lithium ion battery will be described with reference to FIG. In the figure, the same or corresponding parts as those in the first embodiment are designated by the same reference numerals and the description thereof is omitted.

  The winding core 126H used in the prismatic secondary battery of the second embodiment is provided with a stepped portion 126e so that the shape of the portion in contact with the metal foil exposed portions 122A and 124A of the winding core escapes with a step instead of the tapered portion 126b. Is. That is, the winding core 126H is formed of a rectangular plate material, and stepped portions 126e are formed at four corners thereof, and the winding axis direction end 126B is more in the winding axis direction of the winding core than the winding axis direction center portion 126A. It is a shape (V1> V2) where the plate width in the direction orthogonal to is narrow. Therefore, even if the metal foil exposed portions 122A and 124A are displaced inward, they do not come into contact with the core 126H and do not interfere with each other. Hereinafter, the core 126H will be described.

  As shown in FIG. 11, in the core 126H, the shape of the portion in contact with the metal foil exposed portions 122A and 124A escapes at the step portion 126e. The winding core 126H has an expansion operation plate at the innermost periphery or inside thereof at the winding center portion of the metal foil exposed portion laminate 122C, 124C wound in a multi-oval shape at both ends of the wound electrode body 120. 90P and 90N are provided. Then, the spreading operation plates 90P and 90N are pushed open, and the foil laminate of the metal foil exposed portions 122A and 124A is pushed outward in the thickness direction of the wound electrode body 120, whereby the metal foil exposed portions 122A and 124A. The curved portion is displaced inward. However, since the core 126H is provided with the stepped portion 126e at the end 126B, the portion in contact with the metal foil exposed portions 122A and 124A can escape by the stepped portion 126e, and the metal foil exposed portions 122A and 124A are located inside. Even if it is displaced, it does not abut and does not interfere. For this reason, even if the metal foil exposed portions are spread to the outer peripheral side of the core 126H by the spreading operation plates 90P and 90N, no tension acts on the metal foil exposed portions 122A and 124A, and the foil laminates 122C and 124C. Can be prevented from breaking. The other configuration and manufacturing method of the second embodiment are the same as those of the first embodiment.

  In the method of manufacturing the lithium ion secondary battery BC described above, the positive electrode external terminal 113 and the negative electrode external terminal 114 of the lid 111 are connected to the positive electrode current collector plate 115 and the negative electrode current collector plate 116, respectively, and a lid assembly is manufactured. A step of winding the positive electrode 122 and the negative electrode 124 through the separator 121 to form the wound electrode body 120 in a flat shape, a step of integrating the lid assembly 110 with the wound electrode body 120, and a wound electrode The foil laminates 122C and 124C of the positive electrode metal foil exposed portion 122A and the negative electrode metal foil exposed portion 124A to which the active material of the positive electrode 122 and the negative electrode 124 is not applied are pushed from the inner side to the outer side at both end surfaces in the winding axis direction of the body 120. The step of spreading and dividing into two foil laminates, and the two foil laminates divided into the bifurcated connection pieces 115B and 116B of the positive current collector 115 and the negative current collector 116 And a step to continue.

  The step of connecting the two divided foil laminates to the bifurcated connecting pieces 115B and 116B of the positive current collecting plate 115 and the negative current collecting plate 116 is performed by joining surfaces 115C of one connecting piece of the bifurcated connecting pieces 115B and 116B. , 116C, the ultrasonic transducer (horn) WH and the stator WA (anvil) are disposed along the normal line, and either the stator WA or the ultrasonic transducer WH is divided into two. One of the stator and the ultrasonic transducer is brought into contact with the outer circumferential surface of one connection piece 115B, 116B of the bifurcated connection piece 115B, 116B on the inner peripheral surface of one foil laminate, A step of sandwiching the foil laminate divided into two and the joint surface by the stator and applying welding energy to the ultrasonic vibrator to weld the foil laminate and the joint surface.

  The positional relationship between the ultrasonic transducer WH and the stator WA is not limited. That is, the ultrasonic transducer WH may be brought into contact with the outer surface of the bifurcated connecting piece 115B, and the stator WA may be brought into contact with the sheet laminate 122C.

  The above description is an embodiment, and the present invention can be applied to prismatic storage batteries having various structures without departing from the spirit of the present invention, and can be applied not only to lithium ion secondary batteries but also to capacitors. It is.

  Therefore, a positive electrode and a negative electrode on which both sides of the strip-shaped metal foil are provided with an exposed portion of the metal foil along one long side of the metal foil and an active material is applied, and a positive electrode and a negative electrode on a plate-shaped winding core A flat-shaped wound electrode body in which an electrode is wound through a separator, and a square battery in which the exposed portions of each electrode foil are bundled on both sides of the surface of the core and welded to a current collector plate. The core has a width dimension in a direction perpendicular to the winding axis direction, and the width of the wound core on which the exposed portion of the electrode foil (metal foil exposed portion) is wound, the width of the electrode foil on which the active material is coated The present invention relates to various types of prismatic batteries that have a shape that is narrower than the width of the winding core to be rotated, and further has a shape in which the widest width dimension of the core is positioned at least from the exposed portion of the metal foil rather than the coating portion of the positive electrode. Can be applied.

  In the above-described embodiment, an example of a rectangular lithium ion secondary battery is shown as a rectangular battery, so that the power storage element assembly 11 is used. However, in the case of a primary battery instead of a secondary battery, a power generation element assembly is obtained. Of course. Furthermore, although the example which formed the taper part and the level | step-difference part as a winding core which has a shape with a narrow board | plate width was shown, it is comprised so that a width | variety may be narrowed by providing a step-like level | step-difference part and circular arc part in the rectangular four corners. May be.

BC: Lithium ion secondary battery (square battery)
10: Container 11: Power storage element assembly 110: Lid assembly 111: Lid 113: Positive external terminal 114: Negative external terminal 115: Positive current collector 116: Negative current collector 120: Winding electrode 121: Separator 122: Positive electrode (positive electrode)
122A: Positive electrode metal foil exposed portion 122C: Foil laminate 123: Positive electrode mixture layer (positive electrode mixture coating portion)
124: Negative electrode (negative electrode)
124A: negative electrode metal foil exposed portion 124C: foil laminate 125: negative electrode mixture layer (negative electrode mixture coating portion)
126, 126H: Winding core 126A: Center part (winding axis direction center part)
126B: End (winding axis direction end)
126b: Tapered portion 126e: Stepped portions 90N, 90P: Expansion operation plate (expansion member)
91, 92: Feather (metal thin plate)
WA: Anvil (stator)
WH: Horn (Ultrasonic vibrator)
V1: Plate width at the center of the core V2: Plate width at the end of the core

Claims (10)

A prismatic battery comprising a flat wound electrode body in which a strip-shaped electrode is wound around a plate-shaped winding core,
The winding core has a shape in which the plate width in the direction perpendicular to the winding axis direction of the winding core is narrower at the winding axis direction end than the winding axis direction central portion of the winding core. A square battery. The electrode includes a strip-shaped metal foil, a coating portion in which the active material mixture is applied to the metal foil, and a metal in which the active material mixture is not applied along one long side of the metal foil. A foil exposed portion,
2. The wound electrode body according to claim 1, wherein the coating portion is disposed at a central portion in the winding axis direction, and the exposed metal foil portion is disposed at an end portion in the winding axis direction. The described prismatic battery. The electrode includes a positive electrode metal foil, a positive electrode mixture coating portion in which a positive electrode active material mixture is coated on both surfaces of the positive electrode metal foil, and the positive electrode active material along one long side of the positive electrode metal foil. A positive electrode having an uncoated positive electrode metal foil exposed portion, a negative electrode metal foil, a negative electrode mixture coated portion in which a negative electrode active material mixture is coated on both sides of the negative electrode metal foil, and A negative electrode having a negative electrode metal foil exposed portion where the negative electrode active material mixture is uncoated along one long side of the negative electrode metal foil, and
The wound electrode body is a state in which the positive electrode mixture coating portion of the positive electrode and the negative electrode mixture coating portion of the negative electrode are stacked with a separator therebetween in the central portion in the winding axis direction The positive electrode metal foil exposed portion is disposed at one end of the winding core in the winding axis direction, and the negative electrode metal foil exposed portion is disposed at the other end of the winding core in the winding axis direction. The prismatic battery according to claim 1, wherein The electrode has a winding axis direction length of the negative electrode mixture coating portion longer than a winding axis direction length of the positive electrode mixture coating portion,
4. The rectangular battery according to claim 3, wherein the winding core has a winding axis direction length at a center portion in the winding axis direction that is longer than a winding axis direction length of the positive electrode mixture coating portion. . The positions of both ends of the positive electrode mixture coating portion in the winding axis direction are arranged closer to the center in the winding axis direction than the boundary position between the winding axis direction center portion and the winding axis direction end portion of the winding core. ,
The winding axis direction both side end positions of the negative electrode mixture coating part are arranged at the winding axis direction outer side position than the winding axis direction both side end positions of the positive electrode mixture coating part. The prismatic battery according to claim 4.   The prismatic battery according to any one of claims 1 to 5, wherein the winding core is formed of a rectangular plate material, and tapered portions that narrow the plate width are formed at four corners thereof.   The prismatic battery according to any one of claims 1 to 5, wherein the winding core is formed of a rectangular plate material, and stepped portions that narrow the plate width are formed at four corners thereof.   The square according to any one of claims 1 to 7, wherein the core is formed using at least one resin material of PP resin, PBT resin, PPS resin, and PEEK resin. battery.   The square according to any one of claims 1 to 8, wherein the wound electrode body includes an expanding member that widens the exposed portion of the metal foil from the core side to the outer peripheral side. battery.   The prismatic battery according to claim 9, wherein the spreading member is made of a thin metal plate.

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