JP2013045636A - Square battery and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a square battery having a wound body in which the central portion of winding of a foil exposed part can be expanded easily without folding or damaging the metal foil of an electrode sheet.SOLUTION: A square battery 1 has a wound body 6 formed by winding electrode sheets 11, 12 around a shaft core 14, and the wound body 6 has expansion members 15, 16 for expanding the central portion of winding of metal foil laminates 11c, 12c which are wound and laminated at the ends of the winding axis direction. The expansion members 15, 16 consist of a pair of metal thin plates which can deform from a superimposing closed state where the proximal end is fixed to the shaft core 14 to an open state where the distal end is open. At the distal ends of the pair of metal thin plates, open ends 15A, 16A projecting from the end faces of the wound body 6 in the closed state and opening outward in the winding axis direction are provided.

Description

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

  Conventionally, a prismatic battery is known as a battery capable of obtaining a higher volume density than a cylindrical battery. A prismatic battery has a rectangular battery housing in which a flat wound body having an elliptical cross section is formed by winding a belt-like positive electrode sheet and a negative electrode sheet in a spiral shape with a separator interposed therebetween. In addition, an electrolytic solution is injected.

  The prismatic battery is connected to each end of the winding body in the winding axis direction by projecting the foil exposed portions of the positive electrode sheet and the negative electrode sheet, and connecting the connection terminals to the foil exposed portions, thereby shortening the energization path. Reduces resistance and increases output. Such a configuration is also effective for downsizing.

  With regard to the connection form between the wound body and the connection terminal, 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 sheet to form a wound body, the foil exposed portion stacked at the axial end of the wound body is deformed, and the winding center part It is divided into two in the thickness direction with the boundary as the boundary, and each shape is gathered together in the thickness direction to form a shape. The sheet connecting portion of the current collecting terminal is inserted and ultrasonically joined to the collecting portion.

JP 2003-249423 A

  However, in the conventional power storage device described above, when the winding center portion of the foil exposed portion is expanded, the current collector made of the metal foil is mistakenly bent into an unintended shape, deformed, or expanded. There is a possibility that the winding center position is wrong, or a part of the winding center position is bitten when the sheet connecting portion is inserted. Therefore, it is necessary to perform such work carefully so as not to damage the metal foil, and improvement in workability is required.

  The present invention has been made in view of the above points, and an object of the present invention is to easily expand the winding center portion of the foil exposed portion without bending or scratching the metal foil of the electrode sheet. It is to obtain a prismatic battery having a wound body that can be opened.

  The prismatic battery of the present invention that solves the above problems is an electrode in which a mixture layer is coated on both sides of a strip-shaped metal foil and a metal foil exposed portion is formed on one side in the width direction of the metal foil. A prismatic battery having a wound body configured by winding a sheet on a plate-shaped shaft core, wherein the wound body is exposed at a metal foil of the electrode sheet at an end portion in a winding axis direction of the wound body. A winding member that expands the winding center portion of the metal foil laminated portion that is wound and laminated in the thickness direction of the wound body, and the expanding member is based on the shaft core. It consists of a pair of thin metal plates whose ends are fixed and which can be deformed from a closed state where they overlap each other to an open state where the front end side is opened, and the tips of the pair of thin metal plates protrude from the end surface of the winding body in the closed state. An open end portion opened toward the outside in the winding axis direction is provided.

  According to the prismatic battery and the manufacturing method thereof of the present invention, the wound central portion of the foil exposed portion of the wound body can be easily and reliably expanded without damaging the foil exposed portion of the electrode sheet. It is possible to stably connect the rotating body and the current collecting terminal. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

The whole block diagram of the square battery of one embodiment of the present invention. The disassembled perspective view of the square battery of the embodiment. The external appearance perspective view which shows the state which expand | deployed a part of winding body of the embodiment. (A) The perspective view of an axial center in the square battery of the embodiment, (b) The perspective view of an expansion operation board. The flowchart explaining the method of manufacturing the square battery of the embodiment. It is a figure explaining the assembly method of the axial core in the process 1a of the square battery of the embodiment, FIG. 6 (a) is a detailed perspective view explaining the mounting method of an expansion operation board, FIG.6 (b) is a figure. 6A is a cross-sectional perspective view taken along the line AA in FIG. It is a figure explaining the manufacturing method of the winding body in process 1a of the square battery of the embodiment, Drawing 7 (a) is an appearance perspective view showing the state of winding start to an axis, and Drawing 7 (b), The external appearance perspective view which shows the state after winding. The perspective view explaining the content of the process 2 in the square battery of the embodiment. It is a figure explaining the content of the process 3 in the square battery of the embodiment, Fig.9 (a) is an external appearance perspective view, FIG.9 (b) is BB sectional drawing of Fig.9 (a). It is a figure explaining the content of the process 4 in the square battery of the embodiment, Fig.10 (a) is an external appearance perspective view before insertion of a foil opening jig, FIG.10 (b) is FIG.10 (a). CC sectional drawing. It is a figure explaining the content of the process 4 in the square battery of the embodiment, Fig.11 (a) is an external appearance perspective view after insertion of a foil opening jig, FIG.11 (b) is FIG.11 (a). DD sectional drawing. It is a figure explaining the content of the process 5 in the square battery of the embodiment, FIG. 12 (a) is an external perspective view explaining a method of forming a gathering part with a foil opening jig, FIG. 12 (b), The EE sectional view taken on the line of Fig.12 (a). It is a figure explaining the content of the process 6 in the square battery of the embodiment, FIG. 13 (a) is an external appearance perspective view which shows the method of pinching | interposing an assembly part between an expansion member and a current collection connection piece, and welding. FIG. 13 and FIG. 13B are cross-sectional views taken along line FF in FIG. Sectional drawing explaining the state before operating the expansion operation board of the winding body in the square battery of the embodiment. Sectional drawing explaining the state joined to the current collection connection piece with the foil exposure part by operating the expansion operation board of the winding body in the square battery of the embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a lithium ion secondary battery to which the prismatic battery of the present invention is applied and a method for producing the same will be described with reference to the drawings. In addition, this invention is not limited to embodiment below. In addition, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect actual dimensional relationships.

  FIG. 1 is an overall configuration diagram of a prismatic battery according to an embodiment of the present invention. The prismatic battery 1 is a prismatic lithium ion secondary battery, and has a lid 3 at one end opening of a rectangular can with a flat cross section, or a rounded rectangular or oval bottomed rectangular cylindrical battery can (container) 2. Constructed by hermetically sealed. The lid 3 is provided with a liquid injection stopper 4 and a safety valve 5. The liquid injection stopper 4 is used for sealing the liquid injection port after the electrolytic solution is injected. The safety valve 5 is provided in order to prevent an excessive pressure increase in the battery can 2 due to heat generated in the rectangular battery 1.

  FIG. 2 is an exploded perspective view of the prismatic battery shown in FIG. In the battery can 2, a wound body 6 is accommodated as a power generation element in a state of being electrically connected to the positive electrode connection terminal and the negative electrode connection terminal. The positive electrode connection terminal and the negative electrode connection terminal are provided at both ends in the long side direction of the lid 3 and are electrically connected to the positive electrode external terminal 9 and the negative electrode external terminal 10 disposed outside the battery can 2, and And a positive electrode current collecting terminal 7 and a negative electrode current collecting terminal 8 arranged in the battery can 2. In the present embodiment, the battery can 2 and the lid 3 are made of an aluminum plate. The positive current collecting terminal 7, the negative current collecting terminal 8, the positive external terminal 9, the negative external terminal 10 and the lid 3 are insulated by an insulating seal member.

  The positive electrode current collector terminal 7, the negative electrode current collector terminal 8, the positive electrode external terminal 9, and the negative electrode external terminal 10 are fixed to the lid 3 to form a lid assembly. And the winding body 6 is inserted from the one circular arc part between the positive electrode current collection terminal 7 and the negative electrode current collection terminal 8 of a lid | cover assembly, and is integrated by joining etc., and let it be an electric power generation element assembly. The

  The positive electrode current collector terminal 7 is bifurcated from the base 7a extending toward the bottom of the battery can 2 along the positive electrode side end surface of the winding body 6 in the winding axis direction, and from the both sides of the lower end of the base 7a. Furthermore, it has a pair of positive electrode current collection connection pieces 7b, 7b extending in the bottom direction. The pair of positive electrode current collecting connection pieces 7b, 7b has a substantially C shape when viewed from above the battery can 2, and the distance between the connection pieces becomes narrower toward the center side in the long side direction of the lid 3. It is inclined to.

  Similarly, the negative electrode current collector terminal 8 branches into a bifurcated form from the base 8a extending toward the bottom of the battery can 2 along the negative electrode side end surface of the winding body 6 in the winding axis direction, and from both side surfaces of the lower end of the base 8a. In addition, a pair of negative electrode current collector connection pieces 8b and 8b extending in the bottom direction is further provided. The pair of negative electrode current collecting connection pieces 8 b and 8 b are inclined so that the distance between the connection pieces becomes narrower as approaching the center side in the long side direction of the lid 3 when viewed from above the battery can 2.

  The pair of positive electrode current collector connection pieces 7b and 7b are arranged to face each other on the outer side in the thickness direction of the wound body 6 at the positive electrode side end of the wound body 6, and the pair of positive electrode current collection connection pieces 7b and 7b A pair of inner surfaces are joined to an outer surface of a positive electrode connection portion 11d of the wound body 6 described later. The pair of negative electrode current collector connection pieces 8b, 8b are respectively arranged at the negative electrode side end of the wound body 6 so as to face each other in the thickness direction of the wound body 6, and the pair of negative electrode current collection connection pieces 8b, 8b A pair of inner surfaces are joined to an outer surface of a negative electrode connection portion 12d of the wound body 6 described later.

  FIG. 3 is an external perspective view in a state where the winding end side of the wound body is developed. The wound body 6 is configured by winding a positive electrode sheet 11 and a negative electrode sheet 12 around a plate-shaped shaft core 14 with a separator 13 interposed therebetween, and has a flat shape.

  The wound body 6 is formed by winding only the separator 13 on the shaft core 14 on which the positive electrode expansion operation plate 15 and the negative electrode expansion operation plate 16 are mounted, and then the negative electrode sheet 12, the separator 13, the positive electrode sheet 11, and the separator 13. The separators 13 are wound one on top of the other in the innermost circumference. The outermost electrode is the negative electrode sheet 12, and all the positive electrode sheets 11 are sandwiched between the inner peripheral side and the outer peripheral side of the negative electrode sheet 12 via the separator 13. Further, the outermost periphery of the wound body 6 is also wound with one or more layers of separators 13 as necessary to prevent a short circuit.

  The positive electrode sheet 11 has a strip-like positive electrode metal foil made of an aluminum foil or an aluminum alloy foil, and the negative electrode sheet 12 has a strip-like negative electrode metal foil made of a copper foil or a copper alloy foil. The separator 13 is a porous polyethylene resin.

  On both surfaces of the positive electrode metal foil of the positive electrode sheet 11, a positive electrode mixture layer (positive electrode mixture application portion) 11b containing a positive electrode active material is applied. And the negative electrode mixture layer (negative electrode mixture coating part) 12b containing a negative electrode active material is coated on both surfaces of the negative electrode metal foil of the negative electrode sheet 12. FIG. The positive electrode sheet 11 is not coated with the positive electrode active material mixture layer along one long side of the positive electrode metal foil, and the uncoated positive electrode metal foil exposed portion (not yet exposed) where the positive electrode metal foil is exposed. 11a) is also provided. The negative electrode sheet 12 is not coated with the negative electrode active material mixture layer along one long side of the negative electrode metal foil, and the uncoated negative electrode metal foil exposed portion (not yet exposed) where the negative electrode metal foil is exposed. 12a) is also provided.

  The positive electrode sheet 11 and the negative electrode sheet 12 are formed so that the winding axis direction length of the negative electrode mixture layer 12b is longer than the winding axis direction length of the positive electrode mixture layer 11b. In the positive electrode sheet 11, the winding axis direction both side end positions of the positive electrode mixture layer 11b are winding axes more than the boundary position between the winding axis direction central portion 14A and the winding axis direction end portion 14B of the shaft core 14 described later. It is wound around the shaft core 14 so as to be arranged at a position closer to the center in the direction. Further, the negative electrode sheet 12 has an axial core such that the positions of both ends of the negative electrode mixture layer 12b in the winding axis direction are located at positions outside the winding axis in the winding axis direction than the positions of both ends of the positive electrode mixture layer 11b in the winding direction. 14 is wound.

  The positive electrode sheet 11 and the negative electrode sheet 12 have a positive electrode metal foil exposed portion 11a disposed on one side of the winding axis direction, a negative electrode metal foil exposed portion 12a disposed on the other side of the winding axis direction, and the positive electrode mixture layer 11b and the negative electrode The separator 13 is overlapped with the mixture layer 12b so as to be wound around the shaft core 14. A positive electrode metal foil laminated portion 11c in which the positive electrode metal foil exposed portion 11a is wound and stacked is formed at an end portion on one side of the winding body 6 in the winding axis direction. At the end, a negative electrode metal foil laminated portion 12c in which the negative electrode metal foil exposed portion 12a is wound and stacked is formed.

  Next, the configuration of the shaft core 14 will be described with reference to FIGS. 4 (a) and 4 (b). 4A is an external perspective view of the shaft core, and FIG. 4B is an external perspective view of the positive electrode expanding operation plate. In order to facilitate the understanding of the description, as shown in FIG. 4, the winding axis direction of the shaft core is the X direction, the direction perpendicular to the plane of the shaft core is the Z direction, and the X direction of the shaft core and the Z direction The direction orthogonal to the direction will be described as the Y direction.

  The shaft core 14 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, and PEEK (polyether ether ketone) resin. It is formed using.

  The shaft core 14 is a rectangular plate-shaped member corresponding to the planar shape of the wound body 6, and is provided at the center position in the X direction, and the negative electrode mixture of the positive electrode mixture layer 11 b of the positive electrode sheet 11 and the negative electrode sheet 12. A central portion 14A corresponding to a portion where the layer 12b overlaps, and end portions 14B and 14B provided at positions on both sides in the X direction of the central portion 14A and corresponding to the positive electrode metal foil exposed portion 11a and the negative electrode metal foil exposed portion 12a, respectively. I have.

  The shaft core 14 has a shape in which the end portion 14B is narrower in the Y direction than the center portion 14A. For example, the shaft portion 14 is formed by forming tapered portions 14b at four corners of a rectangular plate member. The width is narrowed. The central portion 14A of the shaft core 14 has a pair of parallel outer edge portions 14a and 14a extending along the X direction. The end portion 14B of the shaft core 14 has side end surfaces with a plate width V2 that is narrower than the plate width V1 of the outer edge portions 14a, 14a.

  The shaft core 14 has a positive electrode mixture layer 11b of the positive electrode sheet 11 and a negative electrode mixture layer 12b of the negative electrode sheet 12 arranged at the center portion 14A, and the positive electrode metal foil exposed portion 11a and the negative electrode metal foil exposed portion at the end portions 14B and 14B. 12a is arranged. The separator 13 is interposed between the positive electrode mixture layer 11b and the negative electrode mixture layer 12b, and the positive electrode metal foil exposed portion 11a is disposed at the end portion 14B on one side in the X direction of the shaft core 14, It winds in the state by which the negative electrode metal foil exposure part 12a is arrange | positioned at the edge part 14B of the other side.

  The end portion 14B of the shaft core 14 is formed so that the plate width in the Y direction becomes narrower as it moves in the direction away from the central portion 14A along the X direction. That is, the shaft core 14 is formed with tapered portions 14b at the four corners of the rectangular shaft core 14, and the plate width of the shaft core 14 is narrower than the plate width of the central portion 14A. Further, the shaft core 14 is formed with tapered portions 14b at the four corners, so that the lateral width (the length in the winding axis direction) along the X direction of the central portion 14A is the lateral width (the length in the winding axis direction) of the positive electrode mixture layer 11b. ) Is set larger. The lateral width of the central portion 14A and the lateral width of the negative electrode mixture layer 12b are set to match. With this configuration, ions are efficiently moved during charging / discharging between the positive electrode metal foil of the positive electrode sheet 11 and the negative electrode metal foil of the negative electrode sheet 12.

  A positive electrode expansion operation plate (positive electrode expansion member) 15 is mounted on the positive electrode side end surface of the shaft 14 in the X direction, and a negative electrode expansion operation plate (negative electrode expansion member) 16 is mounted on the negative electrode side end surface. (See FIG. 3). As shown in FIG. 4, recesses 14 c and 14 c to which the positive electrode expanding operation plate 15 and the negative electrode expanding operation plate 16 are mounted are cut out at both ends in the winding axis direction of the shaft core 14. .

  Each recess 14c has a rectangular shape with a size in which the positive electrode expansion operation plate 15 and the negative electrode expansion operation plate 16 are accommodated. The size of the concave portion 14c in the X direction is substantially the same as the size of the end portion 14B, and the size of the concave portion 14c in the Y direction is set slightly larger than the expansion operation plates 15 and 16. And the slit 14d (refer FIG.6 (b)) is provided in the axial center end surface of the recessed part 14c.

  Next, the configuration of the negative electrode expanding operation plate 16 will be described. Since the positive electrode expansion operation plate 15 has substantially the same shape as the negative electrode expansion operation plate 16, the reference numerals of the negative electrode expansion operation plate 16 in the figure are attached with parentheses. Detailed description thereof will be omitted.

  The negative electrode expanding operation plate 16 is fixed by inserting a base end into a slit 14d on the negative electrode side of the shaft core 14, and is deformable from a closed state overlapping each other to an open state where the distal end side is opened. Become. As shown in FIG. 4B, the ends of the pair of thin metal plates constituting the negative electrode expansion operation plate 16 protrude from the end surface of the wound body 6 in the closed state and are opened outward in the winding axis direction. An open end 16A is provided.

  The open end portion 16A of the negative electrode expanding operation plate 16 is bent in a direction away from the opposing metal thin plate at the tip of at least one of the pair of metal thin plates, and moves toward the outer side in the winding axis direction. The core 14 has a bent portion 16a inclined in the direction of increasing the interval in the Z direction.

  In the present embodiment, both of the pair of thin metal plates are provided with a bent portion 16a to form a pair, but the open end portion 16A may be configured to open outward in the winding axis direction. For example, the bent portion 16a may be provided only at the tip of one metal thin plate, and the tip of the other metal thin plate may be extended as it is and faced to the bent portion. In the present embodiment, the pair of bent portions 16a and 16a are provided over the entire tip of the metal thin plate, but it is sufficient that they are provided at positions facing each other, and at least a part of the tip of the metal thin plate. It is good also as a structure provided in.

  In the present embodiment, the negative electrode expanding operation plate 16 is configured by bending a single metal thin plate from the center, and the bent portion is formed at the distal end with the bent portion as a base end. The negative electrode expansion operation plate 16 may be configured by superposing two metal thin plates.

  FIG. 14 is a cross-sectional view illustrating a state before operating the expansion operation plate, and FIG. 15 is a cross-sectional view illustrating a state where the expansion operation plate is operated and joined to the current collector connection piece together with the exposed foil portion. is there. In the closed state shown in FIG. 14, the tip of the negative electrode expansion operation plate 16 protrudes outward from the wound body 6 in the winding axis direction. In the opened state shown in FIG. 15, the negative electrode expansion operation plate 16 does not protrude from the wound body 6. It has a dimensional shape in which the tip is arranged on the inner side in the axial direction.

  In the negative electrode expansion operation plate 16, the thickness of the portion overlapping each other in the closed state is thinner than the thickness of the end portion 14 </ b> B of the shaft core 14. Therefore, interference with the negative electrode metal foil exposed portion 12a can be prevented during winding, and damage to the negative electrode sheet 12 can be prevented.

  The negative electrode expanding operation plate 16 is deformed from a closed state in which the tip ends are opened to an open state by inserting a foil opening jig 22 described later between a pair of bent portions 16a, 16a of the open end portion 16A. The And the winding center part of the negative electrode metal foil lamination | stacking part 12c is expanded, it divides into two in the thickness direction (Z direction), each is gathered in the thickness direction, and the negative electrode side end part of the winding body 6 is set. The pair of negative electrode connecting portions 12d is formed.

  The positive electrode expanding operation plate 15 and the negative electrode expanding operation plate 16 are joined and electrically connected to the positive electrode connecting portion 11d and the negative electrode connecting portion 12d of the wound body 6, respectively. Therefore, it is preferable that the metal thin plate constituting the positive electrode expanding operation plate 15 is made of a material having the same polarity as the positive electrode metal foil of the positive electrode sheet 11, and the metal thin plate constituting the negative electrode expanding operation plate 16 is the negative electrode sheet 12. The negative electrode metal foil is preferably made of a material having the same polarity. Specifically, the positive electrode expansion operation plate 15 is formed of an aluminum foil or an aluminum alloy foil, and the negative electrode expansion operation plate 16 is formed of a copper foil or a copper alloy foil. The positive electrode expansion operation plate 15 and the negative electrode expansion operation plate 16 are preferably made of the same shape, although the materials are different.

  Below, the specific manufacturing method of the square battery 1 which has the said structure is demonstrated using the manufacturing flow of FIG.

  First, the process 1a and the process 1b are performed in parallel, the wound body 6 is manufactured in the process 1a, and the lid assembly is assembled in the process 1b. The assembly of the lid assembly in step 1b is fixed to the lid 3 of the battery can 2 in a state where the positive electrode current collecting terminal 7 and the negative electrode current collecting terminal 8 are insulated. The positive electrode current collector terminal 7 and the positive electrode external terminal 9 as the positive electrode connection terminal, and the negative electrode current collector terminal 8 and the negative electrode external terminal 10 as the negative electrode connection terminal are respectively caulked and fixed to be conductive.

  In Step 2, the wound body 6 formed in Step 1a is mounted on the lid assembly assembled in Step 1b. In Step 3, the wound body 6 is connected to the positive current collector terminal 7 and the negative current collector terminal 8. It is sandwiched between and fixed.

  In step 4, the expansion operation plates 15 and 16 are expanded by the foil opening jig 22, and the winding center portions of the positive electrode metal foil laminated portion 11c and the negative electrode metal foil laminated portion 12c of the wound body 6 are formed. Expanded. In step 5, the expansion operation plates 15 and 16 are continuously operated by the foil opening jig 22 to form the positive electrode connection portion 11d and the negative electrode connection portion 12d in the positive electrode metal foil laminate portion 11c and the negative electrode metal foil laminate portion 12c. The positive electrode connecting portion 11d and the negative electrode connecting portion 12d are sandwiched between the expansion operation plates 15 and 16 and the current collecting connection pieces 7b and 8b, respectively. In step 6, the positive electrode connecting portion 11d and the negative electrode connecting portion 12d are ultrasonically bonded and integrated with the spreading operation plates 15 and 16 and the current collecting connecting pieces 7b and 8b, respectively.

  Step 1a, step 2, step 3, step 4, step 5, and step 6 will be described in more detail with reference to FIGS.

  6 and 7 are diagrams for explaining the contents of step 1a. 6A is a detailed perspective view for explaining a method of mounting the expansion operation plate on the shaft core, and FIG. 6B is a perspective view taken along the line AA in FIG. 6A. is there. FIG. 7A is an external perspective view of the winding body at the start of winding, and FIG. 7B is an external perspective view after the winding body is completed.

  First, as shown in FIG. 6A, the positive electrode expansion operation plate 15 and the negative electrode expansion operation plate 16 are mounted in the recesses 14c and 14c provided at both ends of the shaft core 14, respectively. In the present embodiment, as shown in FIG. 6B, slits 14d and 14d are provided on both end surfaces of the axial center of the recess 14c, and the base end of the positive electrode expanding operation plate 15 and the negative electrode expanding operation plate are provided in each slit 14d. It is mounted by inserting 16 proximal ends.

  As shown in FIG. 7 (a), the winding body 6 first winds only a predetermined number of separators 13 with the positive electrode expanding operation plate 15 and the negative electrode expanding operation plate 16 mounted on the shaft core 14. Then, a separator is interposed between the positive electrode mixture layer 11b of the positive electrode sheet 11 and the negative electrode mixture layer 12b of the negative electrode sheet 12, and the positive electrode metal foil exposed portion 11a is disposed at one end of the winding axis direction. The negative electrode sheet 12, the separator 13, the positive electrode sheet 11, and the separator 13 are overlapped and wound so that the negative electrode metal foil exposed portion 12 a is arranged at the end on the other side in the winding axis direction, as shown in FIG. The flat wound body 6 shown is formed. An open end 15 </ b> A of the positive electrode widening operation plate 15 and an open end 16 </ b> A of the negative electrode widening operation plate 16 protrude from both end surfaces of the winding body 6.

  FIG. 8 is a diagram for explaining the contents of step 2. In step 2, the positive electrode metal foil laminated portion 11c and the negative electrode metal foil laminated portion 12c of the wound body 6 are preliminarily crushed and deformed in the thickness direction (Z direction), and the thickness is compressed and formed into a thin shape. deep. Then, the positive electrode metal foil laminate portion 11c of the wound body 6 is inserted between the pair of positive electrode current collector connection pieces 7b, 7b of the positive electrode current collector terminal 7, and the pair of negative electrode current collector connection pieces of the negative electrode current collector terminal 8 is inserted. The negative electrode metal foil laminated portion 12c of the wound body 6 is inserted between 8b and 8b. Then, the inner surface of the pair of positive electrode current collector connection pieces 7b and 7b is opposed to the outer surface of the positive electrode metal foil laminate portion 11c of the winding body 6, and the pair of negative electrode current collectors is arranged on the outer surface of the negative electrode metal foil laminate portion 12c. The inner surfaces of the connection pieces 8b, 8b are opposed to each other.

  FIG. 9 is a perspective view for explaining the contents of step 3, FIG. 9 (a) is a perspective view for explaining a method of fixing the wound body between a pair of fixing units, and FIG. FIG. 10 is a cross-sectional view taken along line BB in FIG.

  In step 3, the wound body 6 is fixed by being sandwiched between the pair of fixing units 21. The pair of fixed units 21 have a flat plate shape facing the flat surface of the wound body 6, and are disposed on both sides in the thickness direction of the wound body 6.

  And the winding body 6 is pinched | interposed and fixed by mutually approaching relatively. Each fixing unit 21 is provided with a connecting piece presser 21a. The winding body 6 is sandwiched and fixed, and at the same time, the pair of positive electrode current collecting connection pieces 7b and 7b of the positive electrode current collecting terminal 7 is connected to the winding body 6. The pair of negative electrode current collector connection pieces 8b, 8b of the negative electrode current collector terminal 8 are pressed and fixed from both sides in the thickness direction of the wound body 6. The connection piece presser 21a is placed on one side so as to hold down two places on the base 7a side and the tip end side of the positive current collecting connection piece 7b and two places on the base 8a side and the tip end side of the negative electrode current collection connection piece 8b. Two each are provided, and an anvil and a horn, which will be described later, are inserted between the two connection piece holders 21a, and the longitudinal center portions of the positive current collector connection piece 7b and the negative current collection connection piece 8b are welded. It can be joined. The number and position of the connection piece pressers 21a are not limited to the above-described configuration. For example, when both longitudinal ends of the positive current collecting connection piece 7b are welded together, the connection piece pressers 21a of the respective fixing units 21 are connected. It is good also as a structure which makes one and hold | suppresses a longitudinal direction center part.

  10 and 11 are diagrams for explaining the contents of step 4. FIG. 10A is an external perspective view showing a state before the foil opening jig is inserted into the foil laminate, and FIG. 10B is a cross-sectional view taken along the line CC in FIG. . Fig.11 (a) is an external appearance perspective view which shows the state which inserted the foil opening jig | tool into the foil lamination | stacking part, FIG.11 (b) is the DD sectional view taken on the line in FIG.11 (a).

  In step 4, the operation of the expansion operation plates 15 and 16 by the foil opening jig 22 is performed to expand each of the winding center portions of the positive electrode metal foil laminate portion 11c and the negative electrode metal foil laminate portion 12c of the winding body 6. Is made.

  As shown in FIG. 10, the foil opening jig 22 is arranged to face the positive electrode metal foil laminated portion 11 c of the wound body 6 fixed by the fixing unit 21 on the outer side in the winding axis direction. And as shown in FIG. 11, the foil opening jig | tool 22 is moved to the direction which approaches the winding body 6, and the insertion part of the foil opening jig | tool 22 is inserted in the positive electrode metal foil lamination | stacking part 11c. The insertion portion of the opening jig 22 has a sharp shape so that it can be easily inserted between the pair of bent portions 15a of the open end portion 15A, and is further divided into two in the vertical direction (thickness direction of the wound body). It is a mechanism to divide.

  The laminated state of the positive electrode metal foil laminated portion 11c and the negative electrode metal foil laminated portion 12c of the wound body 6 after step 2 has a large individual difference, and conventionally, the wound central portion may be completely closed. Yes, even if the foil opening jig 22 is inserted into the positive electrode metal foil laminate portion 11c and the negative electrode metal foil laminate portion 12c as it is, it is difficult to stably insert the foil opening jig 22 into these winding center portions.

  On the other hand, in the present embodiment, as shown in FIG. 14, as a characteristic configuration of the present invention, winding is performed in a closed state at the ends of a pair of thin metal plates constituting the expansion operation plates 15 and 16. Open end portions 15 </ b> A and 16 </ b> A that protrude from the end surface of the body 6 and open outward in the winding axis direction are formed.

  For example, as shown in FIG. 10B, the open end portion 15A of the positive electrode expanding operation plate 15 protrudes from the end face of the wound body 6 and is bent in a direction away from each other, and moves outward in the winding axis direction. As a result, a pair of bent portions 15a and 15a that are inclined in the direction in which the interval increases are provided. The foil opening jig 22 is moved between the pair of bent portions 15a.

  Therefore, when the foil opening jig 22 is inserted into the positive electrode metal foil laminate portion 11c, the foil opening jig 22 is guided by the open end portion 15A of the positive electrode expanding operation plate 15, and the insertion portion of the foil opening jig 22 is inserted into the positive electrode metal foil laminate portion 11c. It can be inserted between a pair of thin metal plates that are the winding center portion of the metal foil, and can be stably expanded without being influenced by the laminated state of the positive electrode metal foil laminated portion 11c.

  As shown in FIG. 11B, the bent portions 15a and 15a are bent by inserting the foil opening jig 22, and have a shape along the insertion portion of the foil opening jig 22. The bent shape is not maintained, but the bent crease remains.

  The foil opening jig 22 is disposed at a position facing the connection piece presser 21 a of the fixed unit 21. The material of the foil opening jig 22 is preferably a resin having high wear resistance and high hardness, and in the present embodiment, a polypropylene resin is used. However, the present invention is not limited to this, and other materials may be used. A thing may be used.

  FIG. 12 is a diagram for explaining the contents of step 5, FIG. 12 (a) is an external perspective view showing a state in which the foil opening jig is vertically divided and moved, and FIG. 12 (b) is a diagram. 12 (b) is a cross-sectional view taken along line EE in FIG. 12 (a). In step 5, for example, the foil opening jig 22 is divided into upper and lower parts and moved in a state where the insertion part of the foil opening jig 22 is inserted into the center of winding of the positive electrode metal foil laminated portion 11c. Therefore, the positive electrode metal foil laminated portion 11c is gathered in the thickness direction on both sides of the winding center portion to form a pair of positive electrode connection portions 11d (see FIG. 15).

  Then, the positive electrode current collector connecting piece 7b, the positive electrode connecting portion 11d, and the positive electrode expanding operation plate 15 are sandwiched between the foil opening jig 22 and the connecting piece pressing member 21a so as to overlap each other, and are substantially V-shaped. Fixed in shape. As shown in FIG. 15, the positive electrode connection portion 11 d is sandwiched between the positive electrode expansion operation plate 15 and the positive electrode current collector connection piece 7 b, and the expansion operation plate 15 has a tip from the winding body 6. It does not protrude and is disposed at a position on the inner side in the winding axis direction from the end of the positive electrode connecting portion 11d.

  FIG. 13 is an external perspective view for explaining the contents of step 6, and FIG. 13 (a) is a diagram showing a state in which the positive electrode connecting portion, the positive electrode current collecting connecting piece, and the positive electrode expanding operation plate are ultrasonically bonded. FIG.13 (b) is the FF sectional view taken on the line of FIG.13 (a).

  Between the opening jig 22 moved downward in FIG. 13 (b) and the connection piece presser 21a of the lower fixed unit 21, in order from the top, the positive electrode current collector connection piece 7b, the positive electrode connection part 11d, Ultrasonic bonding is performed in a state where the positive electrode expansion operation plate 15 is overlapped and sandwiched, and the positive electrode current collector connection piece 7b, the positive electrode connection portion 11d, and the positive electrode expansion operation plate 15 are integrated. The

  The ultrasonic bonding is performed by sandwiching the horn 23 and the anvil 24 from both sides in the vertical direction with respect to the surface of the positive current collecting connection piece 7b, and ultrasonically vibrating in the G direction orthogonal to the pressing direction while applying pressure. Then, the upper positive electrode connecting portion 11d in FIG. 13B and the negative electrode side (not shown) are also ultrasonically bonded in the same manner.

  According to the prismatic battery 1 having the above-described configuration and the manufacturing method thereof, the foil exposed portions 11a and 12a of the wound body 6 are wound without damaging the foil exposed portions 11a and 12a of the positive electrode sheet 11 and the negative electrode sheet 12. The center portion can be easily and reliably expanded, and the winding body 6 and the current collecting terminals 7 and 8 can be stably connected.

  In addition, the positive electrode expanding operation plate 15 and the negative electrode expanding operation plate 16 do not protrude from the wound body 6 in the opened state, and the tip is disposed on the inner side in the winding axis direction. When the winding body 6 joined to the electric terminal 7 and the negative electrode current collecting terminal 8 is inserted into the battery can 2, the positive electrode expanding operation plate 15 and the negative electrode expanding operation plate 16 are caught in the opening of the battery can 2. Can be prevented, and the assembly work can be performed smoothly.

  And the positive electrode expansion operation board 15 can be used as a contact plate of the positive electrode connection part 11d. Therefore, it is not necessary to prepare a contact plate separately, the number of parts can be reduced, and the step of attaching the contact plate at the time of ultrasonic bonding can be omitted, and the operation can be simplified.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

1 Square battery (lithium ion secondary battery)
2 Battery can 3 Lid 6 Winding body 7 Positive current collecting terminal 7b Positive current collecting connecting piece 8 Negative current collecting terminal 8b Negative current collecting connecting piece 11 Positive electrode sheet 11a Positive metal foil exposed portion 11b Positive electrode mixture layer 11c Positive metal foil lamination Part 11d Positive electrode connection part 12 Negative electrode sheet 12a Negative electrode metal foil exposed part 12b Negative electrode mixture layer 12c Negative electrode metal foil laminated part 12d Negative electrode connection part 14 Axle core 15 Positive electrode expansion operation plate 15A, 16A Open end part 15a, 16a Bending part 16 Negative electrode Expansion operation plate 21 Fixed unit 21a Connection piece holder 22 Foil opening jig

Claims (9)

An electrode sheet in which a mixture layer is coated on both sides of a strip-shaped metal foil and a metal foil exposed portion where the metal foil is exposed on one side in the width direction of the metal foil is formed around a plate-shaped shaft core A prismatic battery having a wound body,
The wound body has a winding center portion of a metal foil laminated portion in which a metal foil exposed portion of the electrode sheet is wound and laminated at an end portion in the winding axis direction of the wound body. It has an expansion member that expands in the vertical direction,
The spreading member is composed of a pair of thin metal plates whose base ends are fixed to the shaft core and can be deformed from a closed state where they overlap each other to an open state where the distal end side is opened. The prismatic battery is provided with an open end portion that protrudes from the end surface of the winding body and opens outward in the winding axis direction.   The open end portion is bent in a direction away from the opposing metal thin plate at the tip of at least one of the pair of metal thin plates, and the interval increases in the direction of moving outward in the winding axis direction. The prismatic battery according to claim 1, wherein the prismatic battery has an inclined bent portion.   The prismatic battery according to claim 2, wherein the bent portion is provided at least at a part of a tip of the metal thin plate. A container that accommodates the wound body, a lid that seals the container, an external terminal provided on the lid, and a connection terminal that electrically connects the external terminal and the metal foil laminate portion And having
The wound body is expanded by dividing the metal foil laminated portion into two in the thickness direction of the wound body with the expanding member as a boundary from the winding center portion of the wound body. 4. The square according to claim 1, wherein the pair of gathering portions gathered together are sandwiched and joined by the pair of spreading members and the connection terminals, respectively. battery.   The said connection terminal has the bifurcated current collection connection piece in which the inclined joining surface which clamps the said pair of gathering part between the said pair of expansion members was formed. Square battery.   4. The front end of the thin metal plate is disposed in an inner side in a winding axis direction than an end portion of the winding body in the opened state in the expanding member. The prismatic battery according to item.   7. The slit according to claim 1, wherein a slit is formed on an end surface of the shaft core, and base ends of the pair of metal thin plates are inserted and fixed. Square battery.   The prismatic battery according to claim 7, wherein the pair of metal thin plates is configured by folding a single metal thin plate in two, and a bent portion thereof is inserted into the slit and fixed. Attaching a base end of an expanding member having an open end portion opened in a direction away from each other to a tip end made of a pair of thin metal plates to a winding axial end portion of a plate-shaped shaft core;
Winding an electrode sheet around the shaft core to form a wound body;
Fixing the electrode external terminal and the electrode current collector terminal to a lid that seals the battery can housing the wound body;
Inserting a foil opening jig into the open end portion of the spreading member from the winding axis direction outside of the winding body, and expanding the winding center portion of the metal foil laminated portion of the winding body;
A step of gathering the expanded metal foil laminate portions in the thickness direction to form electrode connection portions;
And a step of sandwiching and joining the electrode connecting portion between the electrode current collecting terminal and the expanding member.

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