JP6038593B2 - Prismatic secondary battery - Google Patents

Description

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

  Conventionally, a prismatic secondary battery is known as a battery capable of obtaining a higher volume density than a cylindrical battery. A prismatic secondary battery is housed in a rectangular battery housing, which is a flat wound electrode body having a cross-section with an oval cross section formed by winding a strip between a positive electrode and a negative electrode via a separator. In addition, the electrolytic solution is injected.

  In the rectangular secondary battery, the metal foil exposed portions of the positive electrode and the negative electrode are protruded from both ends in the winding axis direction of the wound electrode body, and electrode terminals or current collectors are connected to these metal foil exposed portions, respectively. As a result, the connection resistance due to the shortening of the energization path is reduced and the output is increased. Such a configuration is also effective for downsizing.

  With regard to the connection form between the wound electrode 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.

  Also, a flat wound electrode body is formed by attaching a pair of expanding members to the winding axial end of the plate-shaped winding core and winding the electrode around the winding core in a state where the pair of expanding members are closed. After that, by opening the pair of expanding members in directions away from each other, the winding axial end of the wound electrode body is divided into two in the thickness direction with the winding center as a boundary. An expansion structure has been proposed (see Patent Document 2). The pair of spreading members are held by the winding core by inserting the proximal end portion into a slit formed at the winding axial end of the winding core, and after winding the wound electrode body, The metal foil exposed portion of the electrode body and the current collector are integrally ultrasonically bonded.

JP 2003-249423 A WO2011 / 111196 A1

  Since the pair of expanding members shown in Patent Document 2 is simply held by the core by frictional force or elastic force by inserting the base end into the slit hole of the core before ultrasonic bonding, The force held by the winding core may be weakened due to errors, etc., and it may come off from the winding core due to vibration during transportation, attachment to the winding machine, or winding. There was a risk of displacement in the positional relationship. In addition, when the elastic supporting force is increased, it is difficult to insert the elastic supporting force into the slit hole.

  The present invention has been made in view of the above points, and the object of the present invention is to prevent the spread member from falling off or being displaced from the core, and to prevent the metal foil exposed portion of the wound electrode body from being enlarged. It is an object of the present invention to provide a highly reliable prismatic secondary battery that can securely fix an opening member at a preset position.

  The prismatic secondary battery of the present invention that solves the above problems is a prismatic secondary battery having a flat wound electrode body, and the wound electrode body includes a flat core around which the electrode is wound, An expansion member that is inserted into an insertion hole provided in the winding core and expands a winding axial direction end portion of the winding electrode body, and the expansion is performed on the deep side of the insertion hole. A part of the member is disposed, a part of the winding core is disposed on the front side of the insertion hole, and faces each other, and has a fixing structure in which movement of the expanding member with respect to the winding core is restricted. It is said.

  According to the present invention, it is possible to prevent the spread member from falling off or being displaced from the winding core, and to reliably fix the exposed metal foil portion of the wound electrode body and the spread member at a predetermined position. A highly reliable prismatic secondary battery can be obtained. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

The external appearance perspective view of the square secondary battery in 1st Embodiment. The disassembled perspective view of the square secondary battery shown in FIG. FIG. 3 is an external perspective view of a wound electrode body shown in FIG. 2. The elements on larger scale explaining the structure of the winding core and expansion member in 1st Embodiment. The figure explaining the fixing method of the winding core and expansion member in 1st Embodiment. The figure explaining the fixing method of the winding core and expansion member in 1st Embodiment. AA line sectional view of Drawing 6. Sectional drawing which shows the state before fixation with the winding core and expansion member in 1st Embodiment. Sectional drawing which shows the fixed state of the winding core and expansion member in 1st Embodiment. The figure explaining the fixing method of the winding core and expansion member in 2nd Embodiment. The figure explaining the fixing method of the winding core and expansion member in 3rd Embodiment. BB sectional drawing of FIG. The figure explaining the fixing method of the winding core and expansion member in 4th Embodiment. Sectional drawing which shows the fixed state of the winding core and expansion member in 4th Embodiment. The perspective view explaining the fixing method of the winding core and expansion member in 5th Embodiment. Sectional drawing which shows the fixed state of the winding core and expansion member in 5th Embodiment. The perspective view explaining the other structural example of the expansion member in 5th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, a case of a prismatic lithium ion secondary battery used as a drive source for a hybrid vehicle or an electric vehicle will be described as an example of a prismatic secondary battery.

[First Embodiment]
FIG. 1 is an external perspective view of a prismatic secondary battery according to the present embodiment, and FIG. 2 is an exploded perspective view of the prismatic secondary battery shown in FIG.
The lithium ion secondary battery 1 which is a square secondary battery has a configuration in which a power generation element is accommodated in a battery can 4. The battery can 4 has a rectangular deep-drawn shape having a rectangular bottom surface, and the battery container 2 is formed by sealing the opening opened upward with the battery lid 3. .

  The power generation element has a flat wound electrode body 10. The wound electrode body 10 has a posture in which the winding axis direction extends in the lateral direction parallel to the opening of the battery can 4 and the flat surface extends in the vertical direction along the wide vertical wall surface of the battery can 4. The battery can 4 is housed in a state. The wound electrode body 10 is housed in the battery container 2 in a state in which the outer sides thereof are covered together with the positive electrode current collector plate 62 and the negative electrode current collector plate 72 by an insulating sheet (not shown).

  Both the battery can 4 and the battery lid 3 are made of an aluminum alloy. The battery lid 3 is welded to the battery can 4 by laser welding. The battery lid 3 is provided with a positive electrode terminal component 60 and a negative electrode terminal component 70 to constitute a lid assembly.

  In addition to the positive electrode terminal component 60 and the negative electrode terminal component 70, the battery lid 3 is opened when the pressure in the battery container 2 rises above a predetermined value and is released to discharge the gas in the battery container 2. And a liquid injection port 7 for injecting the electrolytic solution into the battery container 2 is disposed. The liquid injection port 7 is closed by a liquid injection plug 8 after the injection of the electrolytic solution, and is joined and sealed by laser welding the liquid injection plug 8 to the battery lid 3.

  The positive electrode terminal constituting part 60 and the negative electrode terminal constituting part 70 are arranged at positions separated from each other on one side and the other side in the long side direction of the battery lid 3. The positive electrode terminal component 60 and the negative electrode terminal component 70 include a positive electrode external terminal 61 and a negative electrode external terminal 71 disposed outside the battery lid 3, a positive electrode current collector plate 62 disposed inside the battery cover 3, and a negative electrode Current collector plate 72. The positive electrode external terminal 61 and the positive electrode current collector plate 62 and the negative electrode external terminal 71 and the negative electrode current collector plate 72 are electrically connected by connection terminals (not shown), respectively. The positive external terminal 61 and the positive current collector 62 are made of an aluminum alloy, and the negative external terminal 71 and the negative current collector 72 are made of a copper alloy.

  Insulating members 63 and 73 are interposed between the positive electrode external terminal 61, the negative electrode external terminal 71, the positive electrode current collector plate 62, and the negative electrode current collector plate 72, respectively, and electrically insulated from the battery cover 3. Has been. The positive electrode current collector plate 62 and the negative electrode current collector plate 72 are respectively bent at the base portions 62a and 72a extending in the long side direction along the inner side of the battery lid 3 and the long sides of the base portions 62a and 72a. 4 has a pair of connection pieces 62b and 72b that extend toward the bottom of 4 and are conductively connected to the wound electrode body 10. The wound electrode body 10 is disposed and supported between the connection piece 62b of the positive current collector plate 62 and the connection piece 72b of the negative current collector plate 72, and a power generation element is formed by the wound electrode body 10 and the lid assembly. An assembly 5 is configured.

FIG. 3 is an external perspective view showing the details of the wound electrode body 10 shown in FIG.
The wound electrode body 10 is configured by winding the separator 13, the negative electrode plate 12, the separator 15, and the positive electrode plate 14 in this order on the winding core 21. As shown in FIG. 3, the wound electrode body 10 has a flat shape, the outermost electrode plate is the negative electrode plate 12, and the separator 13 is wound further outside.

  The separators 13 and 15 have a role of insulating the positive electrode plate 14 and the negative electrode plate 12. The negative electrode coating part 12a of the negative electrode plate 12 is larger in the width direction than the positive electrode coating part 14a of the positive electrode plate 14, whereby the positive electrode coating part 14a is configured to be sandwiched between the negative electrode coating part 12a without fail. Yes.

  The positive electrode uncoated portion 14b and the negative electrode uncoated portion 12b are connected to current collector plates 62 and 72 of each electrode that are bundled at a flat portion and connected to the external terminals 61 and 71 by welding or the like.

  The separators 13 and 15 are wider than the negative electrode coated portion 12a in the width direction, but are bundled because they are wound at positions where the metal foil surface is exposed at the positive electrode uncoated portion 14b and the negative electrode uncoated portion 12b. This will not interfere with welding.

  The positive electrode plate 14 has a positive electrode coating part 14a in which a positive electrode active material mixture is applied to both surfaces of a positive electrode foil that is a positive electrode current collector, and a positive electrode active part 14 is provided at one end in the width direction of the positive electrode foil. A positive electrode uncoated part (metal foil exposed part) 14b where no material mixture is applied is provided.

  The negative electrode plate 12 has a negative electrode coating part 12a in which a negative electrode active material mixture is applied to both surfaces of a negative electrode electrode foil that is a negative electrode current collector, and a negative electrode active part is disposed at the other end in the width direction of the negative electrode electrode foil. A negative electrode uncoated portion (metal foil exposed portion) 12b to which the material mixture is not applied is provided. The positive electrode uncoated portion 14b and the negative electrode uncoated portion 12b are regions where the metal surface of the electrode foil is exposed, and are wound so as to be disposed at positions on one side and the other side in the winding axis direction.

  In the negative electrode plate 12, 10 parts by weight of polyvinylidene fluoride (hereinafter referred to as PVDF) as a binder is added to 100 parts by weight of amorphous carbon powder as a negative electrode active material, and N as a dispersion solvent. -A negative electrode mixture in which methylpyrrolidone (hereinafter referred to as NMP) was added and kneaded was prepared. This negative electrode mixture was applied to both surfaces of a 10 μm thick copper foil (negative electrode electrode foil) leaving a current collecting portion (negative electrode uncoated portion). Thereafter, drying, pressing, and cutting were performed to obtain a negative electrode plate having a thickness of 70 μm, which does not include a copper foil.

  In this embodiment, the case where amorphous carbon is used as the negative electrode active material is exemplified, but the present invention is not limited to this, and natural graphite capable of inserting and removing lithium ions and various artificial graphites are not limited thereto. The material may be a carbonaceous material such as a material or coke, and the particle shape is not particularly limited to a scale shape, a spherical shape, a fiber shape, a lump shape, or the like.

Regarding positive electrode plate 14, 10 parts by weight of flaky graphite as a conductive material and 10 parts by weight of PVDF as a binder are added to 100 parts by weight of lithium manganate (chemical formula LiMn ₂ O ₄ ) as a positive electrode active material. A positive electrode mixture was prepared by adding and kneading NMP as a dispersion solvent. This positive electrode material mixture was applied to both surfaces of a 20 μm thick aluminum foil (positive electrode electrode foil) leaving a plain current collecting part (positive electrode uncoated part). Thereafter, drying, pressing, and cutting were performed to obtain a positive electrode plate with a thickness of 90 μm, which does not include an aluminum foil.

  Further, in the present embodiment, the case where lithium manganate is used as the positive electrode active material is exemplified, but other lithium manganate having a spinel crystal structure or a lithium manganese composite oxide partially substituted or doped with a metal element or A lithium cobalt oxide or lithium titanate having a layered crystal structure, or a lithium-metal composite oxide in which a part thereof is substituted or doped with a metal element may be used.

  In the present embodiment, the case where PVDF is used as the binder of the coating portion in the positive electrode plate and the negative electrode plate is exemplified, but polytetrafluoroethylene (PTFE), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, Use polymers such as styrene butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride, chloroprene fluoride, acrylic resins, and mixtures thereof. be able to.

  FIG. 4 is a partially enlarged view for explaining the configuration of the winding core and the expanding member in the present embodiment. Since the spreading member has the same configuration on the positive electrode side and the negative electrode side, only the negative electrode side is shown in FIG. 4, and the positive electrode side is marked with the corresponding reference numerals in parentheses. Detailed description is omitted.

  The winding core 21 is made of a substantially rectangular flat plate member corresponding to the planar shape of the wound electrode body 10. The winding core 21 is formed of an insulating material, and in particular, at least one of PP (polypropylene) resin, PBT (polybutylene terephthalate) resin, PPS (polyphenylene sulfide) resin, and PEEK (polyether ether ketone) resin. It is formed using a resin material.

  The winding core 21 includes a positive electrode coating portion 14a of the positive electrode plate 14, a central portion in the center of the winding axis direction (X direction) in which portions corresponding to the negative electrode coating portion 12a of the negative electrode plate 12 are wound, and the positive electrode plate 14 on the one side in the winding axis direction where a portion corresponding to the positive electrode uncoated portion 14b is wound, and a winding shaft on which a portion corresponding to the negative electrode uncoated portion 12b of the negative electrode plate 12 is wound. It has an end on the other side in the direction. The winding core 21 has a length in the winding direction (Y direction) that is shorter at both ends than at the center, and moves outward in the winding axis direction between the center and both ends. Accordingly, an inclined portion that is inclined so as to shorten the length in the winding direction is provided.

  At both ends of the winding core 21, a holding portion 22 is formed integrally with the winding machine (not shown) so that the winding core 21 is detachably held. Two holding portions 22 are provided on each of one side and the other side of the winding core 21 in the winding axis direction, and are arranged in pairs in the winding direction (Y direction).

  Slit-shaped insertion holes 23 are provided at both end portions of the winding core 21 and between the pair of holding portions 22, respectively, and a negative electrode expansion operation plate 31 and a positive electrode expansion operation plate which are expansion members. 41 is mounted separately on one side and the other side in the winding axis direction.

  The negative electrode expanding operation plate 31 is formed of a plate member made of copper alloy. The negative electrode expanding operation plate 31 is held in a state where the base end is inserted into the insertion hole 23 of the winding core 21 in a state where the negative electrode expanding operation plate 31 is overlapped as a set. By expanding in a direction away from each other, the end portion in the winding axis direction on the negative electrode side of the wound electrode body 10 can be expanded.

  The winding axial direction end on the negative electrode side of the wound electrode body 10 has a flat thickness from the winding core 21 to a portion of the negative electrode uncoated portion 12b laminated in a planar shape by a pair of negative electrode expanding operation plates 31. It is set as the expansion state divided into two toward the direction away from each other. And a pair of negative electrode connection part is formed by compressing each in a flat thickness direction.

  In the pair of negative electrode connecting portions, when the wound electrode body 10 is assembled to the lid assembly, the connecting pieces 72b of the negative electrode current collector plate 72 are arranged so as to face each other along the outside of the negative electrode connecting portions. It is ultrasonically welded while being sandwiched between the opening operation plate 31 and joined together (see FIG. 2).

  The positive electrode expanding operation plate 41 is formed of a plate-shaped member made of aluminum alloy. The positive electrode widening operation plate 41 has the same shape as the negative electrode widening operation plate 31, and the base end is inserted into the insertion hole 23 of the winding core 21 and held in a state of being superposed as a set of two sheets. In addition, after the wound electrode body 10 is formed, the ends of the wound electrode body 10 on the positive electrode side of the wound electrode body 10 can be expanded by expanding the tips in directions away from each other. Yes.

  The winding axis direction end of the wound electrode body 10 on the positive electrode side is flattened from the winding core 21 by the portion of the positive electrode uncoated portion 14b that is laminated in a planar shape by the pair of positive electrode expanding operation plates 41. It is set as the expansion state divided into two toward the direction away from each other. And a pair of positive electrode connection part is formed by compressing each in a flat thickness direction.

  In the pair of positive electrode connection portions, when the wound electrode body 10 is assembled to the lid assembly, the connection pieces 62b of the positive electrode current collector plate 62 are arranged so as to face each other along the outside of the positive electrode connection portions, and the connection pieces 62b and the positive electrode expansion portions are arranged. It is ultrasonically welded in a state of being sandwiched between the opening operation plate 41 and integrally joined.

  In the situation before ultrasonic welding in which the negative electrode expansion operation plate 31 and the positive electrode expansion operation plate 41 are simply inserted into the insertion hole 23 of the winding core 21, for example, vibration during conveyance or attachment work to a winding machine There is a risk of falling out of the insertion hole 23 or causing a position shift during rotation by the winding machine or the winding machine.

  Therefore, in the rectangular secondary battery 1 according to the present embodiment, the negative electrode expansion operation plate 31 and the positive electrode expansion operation plate 41 are fixed to the winding core 21 in a state where the negative electrode expansion operation plate 31 and the positive electrode expansion operation plate 41 are inserted and held in the insertion hole 23 of the winding core 21. Thereby, the drop-out from the insertion hole 23 and the position shift are prevented before ultrasonic welding.

5-8 is a figure explaining an example of the fixing method of the winding core and expansion member in this Embodiment.
Between the expansion operation plates 31 and 41 and the winding core 21, the negative electrode expansion operation plate 31 and the positive electrode expansion operation plate 41 are inserted and held in the insertion hole 23 of the winding core 21, and the winding core A fixing means is provided for restricting the movement of the spreading operation plates 31 and 41 with respect to 21 to prevent the drop-out operation and the displacement from the insertion hole 23.

  For example, as shown in FIG. 5, the pair of negative electrode expanding operation plates 31 is provided with a through hole 32 in a base region 31 a that is inserted into the insertion hole 23 of the winding core 21. The through holes 32 are provided at positions where the pair of negative electrode expanding operation plates 31 communicate with each other in a state where the negative electrode expanding operation plates 31 are overlapped with each other and inserted into the insertion hole 23 of the winding core 21.

  Further, at least one flat surface portion 21b of the winding core 21 is provided with a melted portion 24 in which a part of the winding core 21 is partially melted by the heating rod 100 as a heating means. The melted portion 24 is disposed at a position facing the through hole 32 of the negative electrode expanding operation plate 31 inserted into the insertion hole 23. The melted portion 24 is formed in a central portion surrounded by the concave groove 21a, with an annular concave groove 21a provided in the flat portion 21b.

  In order to fix the negative electrode expansion operation plate 31 to the winding core 21, first, a set of two negative electrode expansion operation plates 31 is inserted into the insertion hole 23 of the winding core 21. At that time, the through holes 32 of the two negative electrode expansion operation plates 31 are overlapped and pushed into the winding core 21, and the centers of the through holes 32 are arranged at positions that coincide with the centers of the melted portions 24.

  Next, as shown in FIG. 6, the heating rod 100 heated to a predetermined welding temperature is pressed against the melted portion 24, and the one surface side of the flat surface portion 21 b from the insertion hole 23 that is a part of the winding core. Is softened and melted, and the molten resin is caused to flow into the through-hole 32 and pass through the through-hole 32 of the negative electrode expanding operation plate 31 to reach the other side of the flat portion 21b. The molten resin is cooled and solidified in the through hole 32 to form a welded portion 25 protruding into the through hole 32 (see FIG. 8B).

  As a result, the negative electrode expansion operation plate 31 is fixed to the winding core 21 by the periphery of the through hole 32 being solidified by the welded portion 25 in which the melted portion 24 is melted and solidified by the heating rod 100. That is, a part of the negative electrode expanding operation plate 31 is disposed on the deep side of the insertion hole 23, and a welding portion 25 that is a part of the winding core 21 is disposed on the front side of the insertion hole 23 so as to face each other. The movement of the negative electrode expanding operation plate 31 relative to the winding core 21 is restricted. Therefore, they can be fixed to each other, and the negative electrode expanding operation plate 31 can be prevented from falling off or being displaced from the insertion hole 23.

Note that when the melted portion 24 is melted with the heating rod 100, the melted resin may protrude from the tip of the heating rod 100 and generate a buildup around the heating rod 100. As shown to 8A, since the annular concave groove 21a is provided around the melted portion 24, the built-up around the heating rod 100 can be inserted into the concave groove 21a. Therefore, it is possible to prevent the build-up from being raised and convex than the flat portion 21b, and the positive electrode plate 14, the negative electrode plate 12, and the separators 13 and 15 can be wound around the flat portion 21b without unevenness.
Similarly to the negative electrode expansion operation plate 31, the positive electrode expansion operation plate 41 is also fixed to the winding core 21.

  According to the fixing structure described above, by adjusting the melted state of the melted portion 24 and reducing the size of the welded portion 25, the expansion operation plates 31 and 41 can be somewhat rattled with respect to the winding core 21. It can be fixed in a state that it has, that is, a state that allows movement within a predetermined range.

  Therefore, when the negative electrode connection portion of the wound electrode body 10 is sandwiched between the negative electrode expansion operation plate 31 and the connection piece 72b of the negative electrode current collector plate 72 and ultrasonic welding is performed, and the positive electrode expansion operation plate 41 and the positive electrode When the positive electrode connecting portion of the wound electrode body 10 is sandwiched between the connecting piece 62b of the current collector plate 62 and ultrasonic welding is performed, ultrasonic welding is performed by the looseness of the expansion operation plates 31 and 41 with respect to the winding core 21. Vibration can be absorbed. Therefore, it is possible to prevent breakage or the like from occurring in the negative electrode connecting portion of the negative electrode foil and the positive electrode connecting portion of the positive electrode foil due to vibration of ultrasonic welding.

  The winding core 21 is set to the winding machine after the expansion operation plates 31 and 41 are fixed. Then, the winding start end portions of the separators 13 and 15 are welded to the winding core 21, and the winding start end portions of the negative electrode plate 12 and the positive electrode plate 14 are sandwiched between the separators 13 and 15 and wound. A wound electrode body 10 is formed.

  In the above-described embodiment, the case where the expansion operation plates 31 and 41 and the winding core 21 are fixed by heat welding using the heating rod 100 is described as an example. Good. Further, as a method of fixing the expansion operation plates 31 and 41 to the winding core 21, an adhesive or an adhesive tape can be used.

  According to the above-described lithium ion secondary battery 1 of the present embodiment, the melted portion 24 that is a part of the winding core 21 is melted and wound into the through holes 32 and 42 of the expansion operation plates 31 and 41. A welding portion 25 of the core 21 is provided, a part of the expansion operation plates 31 and 41 is disposed on the back side of the insertion hole 23, and a welding portion that is a part of the winding core is disposed on the front side of the insertion hole 23. 25 is arranged so as to face each other, and the expansion operation plates 31 and 41 are restricted from moving in a direction away from the insertion hole 23 of the winding core 21.

  Therefore, for example, when the positive electrode plate 14 and the negative electrode plate 12 are wound around the winding core 21, or after the winding, the expansion operation plates 31 and 41 fall off from the winding core 21. , It is possible to prevent the displacement. Therefore, it is possible to suppress the occurrence of poor welding when ultrasonically joining the positive electrode connecting portion of the wound electrode body and the positive electrode expanding operation plate 41 and the negative electrode connecting portion and the negative electrode expanding operation plate 31. Therefore, it is possible to provide the prismatic secondary battery 1 having excellent productivity and high reliability.

[Second Embodiment]
FIG. 9 is a diagram for explaining the second embodiment, and corresponds to FIG. 4 in the first embodiment.
What is characteristic in the present embodiment is that a plurality of welding portions 25 for fixing the expansion operation plates 31 and 41 to the winding core 21 are provided for the expansion operation plates 31 and 41, respectively.

  As shown in FIG. 9, on the negative electrode side of the winding core 21, a welding portion 25 for fixing the negative electrode expanding operation plate 31 is a winding direction of the winding core 21, which is a direction orthogonal to the insertion direction of the insertion hole 23 ( Two are provided at predetermined intervals in the (Y direction). Similarly, two welding portions 25 for fixing the positive electrode expanding operation plate 41 are provided on the positive electrode side of the winding core 21 at a predetermined interval in the winding direction (Y direction) of the winding core 21. Yes.

  According to the present embodiment, since a plurality of welding portions 25 are provided for each of the expansion operation plates 31 and 41, each expansion is compared with the first embodiment in which only one point is fixed. While improving the holding strength of the opening operation plates 31 and 41, and preventing the movement in the rotation direction around the fixing portion of each of the opening operation plates 31 and 41, the expansion operation plate 31 and the winding core 21. 41 can be prevented from being held obliquely. In the above-described embodiment, the case where the welded portion 25 is provided with two welded portions 25 with respect to the spreading operation plates 31 and 41 has been described as an example. However, the number of welded portions 25 may be further increased to 3 or more. .

[Third Embodiment]
FIG. 10 is a diagram for explaining the third embodiment. FIG. 10 corresponds to FIG. 4 in the first embodiment, and FIG. 11 is a cross-sectional view taken along the line BB in FIG.

  What is characteristic in the present embodiment is that a part of the through holes 33 and 43 provided in the expansion operation plates 31 and 41 are exposed from the end portion of the winding core 21 and are mutually connected through the through holes 33 and 43. That is, the end portions of the opposing winding core 21 are welded and arranged at a position protruding from the insertion hole 23, and a part of the welding portion 25 is protruded from the end surface of the winding core 21.

  As shown in FIG. 11, the expansion operation plates 31 and 41 are arranged such that part of the through holes 33 and 43 are disposed in the insertion hole 23 of the winding core 21, and the through holes 33 and 43 are disposed outside the end surface of the winding core 21. A part of 43 is arranged. And the to-be-melted part 24 is set in the position which is the one surface side of the plane part 21b of the winding core 21, and opposes the through-holes 33 and 43, for example, presses the heating rod which is not shown in figure, 25 is formed. The welded portion 25 passes through the through holes 33 and 43 of the spreading operation plates 31 and 41 and connects the one surface side and the other surface side of the flat surface portion 21b which is the end portion of the winding core 21, and the winding core The entrance side of the insertion hole 23 of 21 is closed.

  Therefore, a part of the widening operation plates 31 and 41 is disposed on the back side of the insertion hole 23, and a welding part 25 that is a part of the winding core 21 is disposed on the front side of the insertion hole 23 so as to face each other. The expansion operation plates 31, 41 are restricted from moving in a direction away from the insertion hole 23 of the winding core 21, and the expansion operation plates 31, 41 are fixed to the winding core 21.

  In the first and second embodiments described above, the periphery of the melted portion 24 is surrounded by the unmelted portion of the winding core 21 over the entire circumference. Is not surrounded. Therefore, the wall portions on both sides forming the insertion hole 23 of the winding core 21 can be pressed in the direction in which the width of the insertion hole 23 is reduced, and welding can be easily performed.

  In addition, the molten resin melted by the heating rod 100 flows into the insertion hole 23 of the winding core 21 and also flows in a direction protruding from the end face of the winding core 21, so that the molten resin protruding from the tip of the heating rod 100 is meat. It can prevent protruding from the plane part 21b as a scale. Therefore, welding can be facilitated and quality can be stabilized. Furthermore, the expansion operation plates 31 and 41 can be fixed by joining the wall portions on both sides of the insertion hole 23 of the winding core 21 by ultrasonic welding.

[Fourth embodiment]
FIG. 12 is a perspective view illustrating a method of fixing the spreading operation plate to the winding core in the fourth embodiment, and FIG. 13 is a cross-sectional view illustrating a fixing state of the winding core and the spreading operation plate.

  What is characteristic in the present embodiment is that the locking claws 34, 44 provided on the expansion operation plates 31, 41 are engaged with the locking holes 26 provided on the winding core 21, thereby expanding the expansion operation plate 31. , 41 is fixed to the core 21.

  The winding core 21 has a locking hole 26 extending along the winding direction at a position separated from the end surface by a predetermined distance toward the center in the winding axis direction. The locking hole 26 is drilled in a direction intersecting the insertion hole 23 and communicates with the insertion hole 23. The locking holes 26 are formed on both side walls that form the insertion hole 23 of the flat surface portion 21b, and penetrate the flat surface portion 21b.

  The expansion operation plates 31 and 41 have locking claws 34 and 44 that are locked to the locking holes 26 by inserting a part of the expansion operation plates 31 and 41 into the insertion holes 23 of the winding core 21. ing.

  The locking claws 34, 44 are provided at positions facing the locking holes 26, and move from the front side in the insertion direction toward the rear side in the insertion direction (right side in FIG. 13) opposite to the insertion direction. It has a tapered shape that gradually moves toward the outer side in the width direction of the insertion hole 23.

  Each of the expansion operation plates 31 and 41 is a set of two pieces, and each of the locking claws 34 and 44 has a shape that expands into a letter C when in contact with each other. The distance between the tips is set to be larger than the width of the insertion hole 23 of the winding core 21.

  When the two sheets are combined and inserted into the insertion hole 23 of the winding core 21, the locking claws 34 and 44 of the expansion operation plates 31 and 41 are elastically deformed and the bending angle thereof is restricted to a flat shape. It is inserted into the insertion hole 23 in a state. And when it moves to the position which overlaps with the locking hole 26 of the winding core 21, it opens in the direction away from each other and enters into the locking hole 26. Therefore, the tips of the locking claws 34 and 44 are locked in the locking holes 26, and the expansion operation plates 31 and 41 are prevented from falling off the winding core 21.

  Therefore, as compared with the first to third embodiments described above, it is possible to fix the expansion operation plates 31 and 41 simply by inserting them into the insertion hole 23 of the winding core 21, and the processing becomes easy. In addition, the production cost can be reduced and the production efficiency can be improved.

[Fifth Embodiment]
FIG. 14 is a perspective view illustrating a method of fixing the spreading operation plate to the winding core in the fifth embodiment, and FIG. 15 is a cross-sectional view illustrating a fixing state of the winding core and the spreading operation plate.

  What is characteristic in the present embodiment is that the locking claws 35 and 45 that are locked in the locking hole 26 have a mountain shape with a cross-sectional shape.

  The locking claws 35, 45 are first moved toward the outer side in the width direction of the insertion hole 23 as moving from the front side in the insertion direction to the insertion hole 23 of the expansion operation plates 31, 41 toward the rear side in the insertion direction. An inclined surface portion and a second inclined surface portion that moves toward the center in the width direction of the insertion hole 23 as it moves continuously to the rear side in the insertion direction following the first inclined surface portion.

  The locking claws 34 and 44 in the fourth embodiment have a flat plate shape and are bent only at the base end portion of the cantilever, but in the present embodiment, the locking claws 35 and 45 have their cross-sectional shapes. Since it has a mountain shape that forms a square shape, it can be bent at both the base end and the top of the cantilever. Therefore, the strength of the locking claws 35 and 45 as a stopper is improved, and the gap between the winding core 21 and the locking hole 26 can be further reduced, and the movement of the locking claws 35 and 45 with respect to the winding core 21 can be reduced. The backlash degree, which is the amount, can be reduced.

  In addition, since the two expansion operation plates 31 and 41 are stacked, the positions of the locking claws 35 and 45 are shifted so that the uneven portions interfere with each other, and the locking claws 35 and 45 do not bend properly. There is a possibility. In that case, as shown in FIG. 16, there is a shift when the two claws 35 and 45 are shifted to one side and the other side in the longitudinal direction of the locking hole 26 to overlap each other. However, a stable bending effect can be obtained without interference.

  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.

DESCRIPTION OF SYMBOLS 1 Square secondary battery 2 Battery container 3 Battery cover 4 Battery can 5 Power generation element 10 Winding electrode body 21 Winding core 23 Insertion hole 24 Melting part 25 Welding part 31 Negative electrode expansion operation board (expansion member)
32, 33, 42, 43 Through-hole 41 Positive electrode expansion operation plate (expansion member)
60 positive electrode terminal component 62 positive electrode current collector plate 70 negative electrode terminal component 72 negative electrode current collector plate 100 heating rod

Claims (4)

A prismatic secondary battery having a flat wound electrode body,
The wound electrode body is inserted into a flat core around which the electrode is wound, and an insertion hole recessed in the wound core, and widens the winding axial end of the wound electrode body. An expansion member,
The spreading member has a through hole formed in an insertion portion to be inserted into the insertion hole of the winding core,
The winding core has a welded portion in which a part of the winding core is melted and protrudes into the through hole . In the state where the expanding member is inserted into the insertion hole of the winding core, a part of the through hole is exposed from the end of the winding core,
2. The prismatic secondary battery according to claim 1 , wherein ends of the winding cores facing each other through the through holes are welded to the winding cores. The prismatic secondary battery according to claim 1 , wherein a plurality of the welded portions are provided. 4. The prismatic secondary battery according to claim 3 , wherein the plurality of welded portions are provided at predetermined intervals in a winding direction orthogonal to an insertion direction of the insertion hole.

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