JP2011159440A - Cylindrical secondary battery and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent internal short circuit due to a foreign matter entering from a gap between a positive electrode and a separator in a cylindrical secondary battery. <P>SOLUTION: An upper side end part of a first separator 13 and the upper side end part of a second separator 14 which are positioned on the outer periphery further than the positive electrode current collector member 31 and are positioned on the upper side than a negative electrode mixture 12b installed at least on the negative electrode sheet 12a are made to be inclined toward the positive electrode current collector member 31 side. Thereby, the upper side end part of the second separator 14 covers the upper part of the positive electrode 11, and accordingly, a foreign matter which becomes a cause of internal short circuit is prevented from entering from a gap of the second separator 14 and the positive electrode 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  In a cylindrical secondary battery represented by a lithium secondary battery or the like, a positive electrode formed with a positive electrode mixture and a negative electrode formed with a negative electrode mixture are wound around a shaft core via a separator. An electrode group is configured. The positive electrode mixture is formed on both surfaces of the positive electrode sheet, and one side edge portion in the longitudinal direction of the positive electrode sheet is a positive electrode mixture untreated portion where no positive electrode mixture is formed.

  Since the positive electrode is welded to the positive electrode current collecting member in the untreated portion of the positive electrode mixture, a positive lead called a tab is usually formed integrally with the positive electrode sheet by pressing or the like. The same applies to the negative electrode side, in which the negative electrode mixture is formed on both sides of the negative electrode sheet, and is welded to the negative electrode current collector member on the negative electrode mixture untreated portion provided at one side edge in the longitudinal direction of the negative electrode sheet. The negative electrode lead is formed integrally with the negative electrode sheet by pressing or the like.

The positive electrode and the negative electrode in the electrode group may be short-circuited when, for example, burrs or the like generated when the positive lead or the negative lead is formed by pressing pierce the separator. As described above, when the positive electrode and the negative electrode are short-circuited in a spot manner, battery performance is deteriorated such that a necessary voltage cannot be obtained.
For this reason, there is known a structure in which the side opposite to the one side in the longitudinal direction where the positive electrode lead is provided in the positive electrode sheet where burrs are likely to occur is covered by folding the adjacent separator. Yes. In this way, there is no risk of burrs or the like breaking through the two separators, and an internal short circuit can be prevented (for example, see Patent Document 1).

JP 2008-4476 A

However, even after the electrode group is housed in the battery container and the nonaqueous electrolyte is injected into the battery container, an internal short circuit occurs. Although the details of this phenomenon will be described later, the main point is that ions are generated from the positive electrode side due to the foreign matter mixed in the non-aqueous electrolyte, penetrate the separator and grow on the negative electrode, that is, on the negative electrode. This is due to the phenomenon of deposition and deposition. As a result, the deposit produced on the negative electrode causes an internal short circuit between the positive electrode and the negative electrode.
The invention described in the above-mentioned prior art does not solve the internal short circuit caused by this phenomenon.

  In the cylindrical secondary battery of the present invention, the first separator, the positive electrode in which the positive electrode mixture is formed on both surfaces of the positive electrode sheet, and the negative electrode mixture are formed on both surfaces of the second separator and the negative electrode sheet around the shaft core. And a positive electrode current collecting member disposed on the upper side in the axial direction of the axial core, the positive electrode is integrally formed on the positive electrode sheet, and the positive electrode current collecting member A secondary battery having a plurality of positive electrode leads connected to the first electrode, located on the outer periphery of the positive electrode current collector and at least on the upper side of the negative electrode mixture formed on the negative electrode sheet The upper-side end portion of the separator and the upper-side end portion of the second separator are inclined toward the positive electrode current collecting member side.

  In addition, the method for manufacturing a cylindrical secondary battery according to the present invention includes a first separator, a positive electrode mixture formed on both surfaces of the positive electrode sheet, and a positive electrode sheet along one side of the positive electrode sheet. Winding a positive electrode having a plurality of integrally formed positive leads, a second separator, and a negative electrode having a negative electrode mixture formed on both sides of the negative electrode sheet to form an electrode group; A step of attaching a positive electrode current collector to the upper part of the shaft core; and an upper side end of the first separator located on the outer periphery of at least the negative electrode mixture provided on the negative electrode sheet And a step of inclining the upper side end of the second separator and the second separator toward the positive electrode current collector member, and a step of connecting a plurality of positive electrode leads of the positive electrode sheet to the positive electrode current collector member, To do.

  According to the cylindrical secondary battery and the method of manufacturing the same of the present invention, the upper side end of the separator is inclined toward the positive electrode current collecting member, and covers the upper part between the positive electrode and the separator. For this reason, it can prevent that the foreign material which causes an internal short circuit generate | occur | produces from between a positive electrode and a separator.

Sectional drawing which shows one Embodiment of the cylindrical secondary battery of this invention. FIG. 2 is an exploded perspective view of the cylindrical secondary battery shown in FIG. 1. The perspective view of the state which cut | disconnected a part for showing the detail of the electrode group of FIG. The expanded sectional view which concerns on the principal part of this invention which shows the joining state of the electrode group illustrated by FIG. 1, and a positive electrode current collection member. FIG. 5 is an enlarged plan view showing a state before the electrode group and the positive electrode current collector shown in FIG. 4 are joined. The expansion perspective view for demonstrating the method of connecting each structural member which comprises an electrode group to a positive electrode current collection member. FIG. 7 is an enlarged perspective view of a shaping jig having a cylindrical hollow portion illustrated in FIG. 6. FIG. 8 is an enlarged perspective view illustrating a state where the shaping jig illustrated in FIG. 7 is divided. The perspective view for demonstrating the method of welding a positive electrode lead using the shaping jig. The expanded sectional view which shows the modification of this invention.

-Structure of cylindrical secondary battery-
Hereinafter, a cylindrical secondary battery of the present invention will be described with reference to the drawings, taking a lithium ion cylindrical secondary battery as an embodiment.
FIG. 1 is a cross-sectional view showing an embodiment of the cylindrical secondary battery of the present invention, and FIG. 2 is an exploded perspective view of the cylindrical secondary battery shown in FIG.
The cylindrical secondary battery 1 has dimensions of, for example, an outer diameter of 40 mmφ and a height of 100 mm. In the cylindrical secondary battery 1, components for power generation described below are accommodated in a bottomed cylindrical battery container 2 and a hat-type upper lid 3.

The bottomed cylindrical battery case 2 is formed with a groove 2a protruding on the inner side of the battery case 2 on the upper end side which is the open side.
Reference numeral 10 denotes an electrode group having a shaft core 15 at the center, and a positive electrode and a negative electrode wound around the shaft core 15. FIG. 3 is a perspective view showing the details of the structure of the electrode group 10, with a part thereof cut. As shown in FIG. 3, the electrode group 10 has a configuration in which the positive electrode 11, the negative electrode 12, and the first and second separators 13 and 14 are wound around the outer periphery of the shaft core 15.

  The shaft core 15 has a hollow cylindrical shape, and the first separator 13 is wound on the innermost periphery in contact with the outer periphery of the shaft core 15, and the positive electrode 11, the second separator 14, and the negative electrode are disposed outside the first core 13. 12 are stacked and wound in this order. The outermost periphery is the negative electrode 12 and the first separator 13 wound around the outer periphery. The outermost periphery may be the second separator 14. The first separator 13 at the outermost periphery is stopped by the adhesive tape 19 (see FIG. 2).

  The positive electrode 11 is formed of an aluminum foil and has a long shape. The positive electrode 11 includes a positive electrode sheet 11a and a positive electrode processing portion in which a positive electrode mixture 11b is applied to both surfaces of the positive electrode sheet 11a. The upper side edge along the longitudinal direction of the positive electrode sheet 11a is a positive electrode mixture untreated portion 11c where the positive electrode mixture 11b is not applied and an aluminum foil is exposed. In the positive electrode mixture untreated portion 11 c, a large number of positive electrode leads 16 protruding upward in parallel with the shaft core 15 are integrally formed at equal intervals.

  The positive electrode mixture 11b includes a positive electrode active material, a positive electrode conductive material, and a positive electrode binder. The positive electrode active material is preferably lithium oxide. Examples include lithium cobaltate, lithium manganate, lithium nickelate, lithium composite oxide (lithium oxide containing two or more selected from cobalt, nickel, and manganese). The positive electrode conductive material is not limited as long as it can assist transmission of electrons generated by the occlusion / release reaction of lithium in the positive electrode mixture to the positive electrode. Examples of the positive electrode conductive material include graphite and acetylene black.

  The positive electrode binder can bind the positive electrode active material and the positive electrode conductive material, and can bind the positive electrode mixture and the positive electrode current collector, and should not deteriorate significantly due to contact with the non-aqueous electrolyte. There is no particular limitation. Examples of the positive electrode binder include polyvinylidene fluoride (PVDF) and fluororubber. The method for forming the positive electrode mixture layer is not limited as long as the positive electrode mixture is formed on the positive electrode. As an example of a method of forming the positive electrode mixture 11b, a method of applying a dispersion solution of constituent materials of the positive electrode mixture 11b on the positive electrode sheet 11a can be given.

  Examples of a method for applying the positive electrode mixture 11b to the positive electrode sheet 11a include a roll coating method, a slit die coating method, and the like. As an example of a solvent for the dispersion solution in the positive electrode mixture 11b, N-methylpyrrolidone (NMP), water, or the like is added, and the kneaded slurry is uniformly applied to both sides of an aluminum foil having a thickness of 20 μm and dried. Cut with a press. An example of the coating thickness of the positive electrode mixture 11b is about 40 μm on one side. When the positive electrode sheet 11a is cut by pressing, the positive electrode lead 16 is integrally formed. All the positive leads 16 have substantially the same length.

  The negative electrode 12 is formed of a copper foil and has a long shape. The negative electrode 12 includes a negative electrode sheet 12a and a negative electrode processing portion in which a negative electrode mixture 12b is applied to both surfaces of the negative electrode sheet 12a. The lower side edge along the longitudinal direction of the negative electrode sheet 12a is a negative electrode mixture untreated portion 12c where the negative electrode mixture 12b is not applied and the copper foil is exposed. In the negative electrode mixture untreated portion 12c, a large number of negative electrode leads 17 extending in the direction opposite to the positive electrode lead 16 are integrally formed at equal intervals.

  The negative electrode mixture 12b includes a negative electrode active material, a negative electrode binder, and a thickener. The negative electrode mixture 12b may have a negative electrode conductive material such as acetylene black. Graphite carbon is preferably used as the negative electrode active material. By using graphite carbon, a lithium ion secondary battery for a plug-in hybrid vehicle or an electric vehicle requiring a large capacity can be manufactured. The formation method of the negative electrode mixture 12b is not limited as long as the negative electrode mixture 12b is formed on the negative electrode sheet 12a. As an example of a method of applying the negative electrode mixture 12b to the negative electrode sheet 12a, a method of applying a dispersion solution of constituent materials of the negative electrode mixture 12b onto the negative electrode sheet 12a can be mentioned. Examples of the coating method include a roll coating method and a slit die coating method.

  As an example of a method of applying the negative electrode mixture 12b to the negative electrode sheet 12a, N-methyl-2-pyrrolidone or water as a dispersion solvent is added to the negative electrode mixture 12b, and the kneaded slurry is made of a rolled copper foil having a thickness of 10 μm. After uniformly coating on both sides and drying, cut with a press. An example of the coating thickness of the negative electrode mixture 12b is about 40 μm on one side. When the negative electrode sheet 12a is cut by pressing, the negative electrode lead 17 is integrally formed. All the negative leads 17 have substantially the same length.

When the width of the first separator 13 and the second separator 14 is WS, the width of the negative electrode mixture 12b formed on the negative electrode sheet 12a is WC, and the width of the positive electrode mixture 11b formed on the positive electrode sheet 11a is WA , So as to satisfy the following formula.
WS>WC> WA (see FIG. 3)
That is, the width WC of the negative electrode mixture 12b is always larger than the width WA of the positive electrode mixture 11b. In the case of a lithium ion secondary battery, lithium as a positive electrode active material is ionized and permeates the separator. However, when the negative electrode active material is not formed on the negative electrode side and the negative electrode sheet 12b is exposed, the negative electrode sheet This is because lithium is deposited on 12a and causes an internal short circuit.

The separator 13 is, for example, a polyethylene porous film having a thickness of 40 μm.
1 and 3, a hollow cylindrical shaft core 15 is formed with a large-diameter groove 15a on the inner surface of the upper end portion in the axial direction (vertical direction in the drawing), and a positive current collecting member 31 is press-fitted into the groove 15a. Has been. The positive electrode current collecting member 31 is formed of, for example, aluminum, and has a disk-like base portion 31a, a lower cylindrical portion 31b that protrudes toward the shaft core 15 side at the inner peripheral portion of the base portion 31a and is press-fitted into the inner surface of the shaft core 15. And an upper cylindrical portion 31c protruding toward the upper lid 3 at the outer peripheral edge. An opening 31d (see FIG. 2) for discharging a gas generated inside the battery is formed in the base 31a of the positive electrode current collecting member 31.

  All of the positive leads 16 of the positive electrode sheet 11 a are welded to the upper cylindrical portion 31 c of the positive current collector 31. In this case, as shown in FIG. 2, the positive electrode lead 16 is overlapped and bonded onto the upper cylindrical portion 31 c of the positive electrode current collecting member 31. Since each positive electrode lead 16 is very thin, a large current cannot be taken out by one. Therefore, a large number of positive leads 16 are formed at predetermined intervals over the entire length from the start to the end of winding around the shaft core 15.

Since the positive electrode current collecting member 31 is oxidized by the electrolytic solution, the reliability can be improved by forming it with aluminum. When the surface of aluminum is exposed by some processing, an aluminum oxide film is immediately formed on the surface, and this aluminum oxide film can prevent oxidation by the electrolytic solution.
Moreover, by forming the positive electrode current collecting member 31 from aluminum, the positive electrode lead 16 of the positive electrode sheet 11a can be welded by ultrasonic welding, spot welding, or the like.

On the outer periphery of the lower end portion of the shaft core 15, a step portion 15b having a small outer diameter is formed, and the negative electrode current collector 21 is press-fitted and fixed to the step portion 15b. The negative electrode current collecting member 21 is formed of, for example, copper, and an opening 21b that is press-fitted into the step portion 15b of the shaft core 15 is formed in a disk-shaped base portion 21a. An outer peripheral cylindrical portion 21c that protrudes out is formed.
All of the negative electrode leads 17 of the negative electrode sheet 12a are welded to the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 21 by ultrasonic welding or the like. Since each negative electrode lead 17 is very thin, a large number of negative leads 17 are formed at predetermined intervals over the entire length from the start of winding to the shaft core 15 to take out a large current.

  The negative electrode lead 17 of the negative electrode sheet 12a and the ring-shaped pressing member 22 are welded to the outer periphery of the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 21. A number of the negative electrode leads 17 are brought into close contact with the outer periphery of the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 21, and the holding member 22 is wound around the outer periphery of the negative electrode lead 17 to be temporarily fixed, and are welded in this state.

  A negative electrode conducting lead 23 made of copper is welded to the lower surface of the negative electrode current collecting member 21. The negative electrode conducting lead 23 is welded to the battery container 2 at the bottom of the battery container 2. The battery container 2 is formed of, for example, carbon steel having a thickness of 0.5 mm, and the surface thereof is plated with nickel. By using such a material, the negative electrode energizing lead 23 can be welded to the battery container 2 by resistance welding or the like.

  The positive electrode lead 16 of the positive electrode sheet 11 a and the ring-shaped pressing member 32 are welded to the outer periphery of the upper cylindrical portion 31 c of the positive electrode current collecting member 31. A number of the positive leads 16 are brought into close contact with the outer periphery of the upper cylindrical portion 31 c of the positive current collecting member 31, and the pressing member 32 is wound around the outer periphery of the positive lead 16 and temporarily fixed, and is welded in this state.

  A large number of positive electrode leads 16 are welded to the positive electrode current collecting member 31, and a large number of negative electrode leads 17 are welded to the negative electrode current collecting member 21, whereby the positive electrode current collecting member 31, the negative electrode current collecting member 21 and the electrode group 10 are integrated. A unitized power generation unit 20 is configured (see FIG. 2). However, in FIG. 2, for the convenience of illustration, the negative electrode current collecting member 21, the pressing member 22, and the negative electrode energizing lead 23 are illustrated separately from the power generation unit 20.

  In addition, a flexible connection member 33 configured by laminating a plurality of aluminum foils is joined to the upper surface of the base portion 31a of the positive electrode current collecting member 31 by welding one end thereof. The connection member 33 can flow a large current by laminating and integrating a plurality of aluminum foils, and is provided with flexibility. In other words, it is necessary to increase the thickness of the connecting member in order to pass a large current, but if it is formed of a single metal plate, the rigidity increases and the flexibility is impaired. Therefore, a large number of aluminum foils having a small thickness are laminated to give flexibility. The connecting member 33 has a thickness of, for example, about 0.5 mm, and is formed by stacking five aluminum foils having a thickness of 0.1 mm.

On the upper cylinder part 31c of the positive electrode current collecting member 31, a ring-shaped insulating plate 41 made of an insulating resin material having a circular opening 41a is placed.
The insulating plate 41 has an opening 41a (see FIG. 2) and a side 41b protruding downward. A connection plate 35 is fitted in the opening 41 a of the insulating material 41. The other end of the connection member 33 is welded and joined to the lower surface of the connection plate 35. In this case, the connection member 33 is curved about half a circumference on the other end side, and the same surface as the surface welded to the positive electrode current collector 31 is welded to the connection plate 35.

  The connection plate 35 is formed of an aluminum alloy, and has a substantially dish shape that is substantially uniform except for the central portion and is bent at a slightly lower position on the central side. The thickness of the connection plate 35 is, for example, about 1 mm. At the center of the connecting plate 35, a thin dome-shaped projection 35a is formed, and a plurality of openings 35b (see FIG. 2) are formed around the projection 35a. The opening 35b has a function of releasing gas generated inside the battery.

  The protrusion 35 a of the connection plate 35 is joined to the bottom surface of the center portion of the diaphragm 37 by resistance welding or friction diffusion bonding. The diaphragm 37 is formed of an aluminum alloy, and has a circular cut 37 a centering on the center of the diaphragm 37. The cut 37a is formed by crushing the upper surface side into a V shape by pressing and thinning the remainder. The diaphragm 37 is provided for ensuring the safety of the battery. When the internal pressure of the battery rises, as a first stage, the diaphragm 37 warps upward, peels off the joint with the protruding portion 35a of the connection plate 35, and connects the connection plate 35. The connection with the connection plate 35 is cut off. As a second stage, when the internal pressure still rises, it has a function of cleaving at the cut 37a and releasing the internal gas.

  The diaphragm 37 fixes the peripheral portion of the upper lid 3 at the peripheral portion. As shown in FIG. 2, the diaphragm 37 initially has a side portion 37 b erected vertically toward the upper lid 3 side at the peripheral portion. The upper lid 3 is accommodated in the side portion 37b, and the side portion 37b is bent and fixed to the upper surface side of the upper lid 3 by caulking.

The upper lid 3 is made of iron such as carbon steel and is plated with nickel. The upper lid 3 is a disc-shaped peripheral portion 3a that comes into contact with the diaphragm 37, and a headless bottomless cylindrical portion that protrudes upward from the peripheral portion 3a. It has a hat shape with 3b. An opening 3c is formed in the cylindrical portion 3b. The opening 3c is for releasing gas to the outside of the battery when the diaphragm 37 is cleaved by the gas pressure generated inside the battery.
When the upper lid 3 is made of iron, it can be joined to another cylindrical secondary battery made of iron by spot welding when joining in series with another cylindrical secondary battery. It is.

  A gasket 43 is provided so as to cover the side portion 37 b and the peripheral edge portion of the diaphragm 37. As shown in FIG. 2, the gasket 43 is initially formed with an outer peripheral wall portion 43 b erected substantially vertically toward the upper direction on the peripheral edge of the ring-shaped base portion 43 a, and on the inner peripheral side. , And a cylindrical portion 43c formed to hang substantially vertically downward from the base portion 43a.

  As will be described in detail later, the outer peripheral wall 43b of the gasket 43 is bent together with the battery container 2 by a press or the like, and the diaphragm 37 and the upper lid 3 are pressed in the axial direction by the base 43a and the outer peripheral wall 43b. It is caulked. Thereby, the upper lid 3 and the diaphragm 37 are fixed to the battery container 2 via the gasket 43.

  A predetermined amount of non-aqueous electrolyte is injected into the battery container 2. As an example of the non-aqueous electrolyte, it is preferable to use a solution in which a lithium salt is dissolved in a carbonate solvent. Examples of lithium salts include lithium fluorophosphate (LiPF6), lithium fluoroborate (LiBF6), and the like. Examples of carbonate solvents include ethylene carbonate (EC), dimethyl carbonate (DMC), propylene carbonate (PC), methyl ethyl carbonate (MEC), or a mixture of solvents selected from one or more of the above solvents, Is mentioned.

FIG. 4 is an enlarged cross-sectional view according to the main part of the present invention, showing a joined state of the electrode group 10 and the positive electrode current collecting member 31 shown in FIG.
As described above, all of the many positive leads 16 formed on the positive electrode 11 are welded to the outer periphery of the upper cylindrical portion 31 c of the positive current collecting member 31 by ultrasonic welding or the like. In this case, conventionally, the positive electrode lead 16 is distributed almost uniformly around the entire periphery of the upper cylindrical portion 31 c of the positive electrode current collecting member 31, and the pressing member 32 is wound around the outer periphery of the positive electrode lead 16. And the method of welding the positive electrode lead 16 and the presser ring 32 to the positive electrode current collection member 31 by ultrasonic welding etc. was used.

  In the case of the conventional method described above, each positive electrode lead 16 welded to the positive electrode current collector 31 is pulled toward the positive electrode current collector 31 side. For this reason, the portion of the positive electrode mixture untreated portion 11 c of the positive electrode sheet 11 a corresponding to the base portion of each positive electrode lead 16 is brought together with each positive electrode lead 16 toward the positive electrode current collecting member 31 side. For this reason, the space | interval of the part corresponding to each positive electrode lead 16 of the positive electrode mixture unprocessed part 11c and the 2nd separator 14 adjacent to the outer side becomes wide.

  By the way, in the non-aqueous electrolyte injected into the battery container 2, a large number of minute conductive foreign matters are mixed. Such foreign matter is generated in the manufacturing process of the positive electrode sheet 11 and the negative electrode sheet 12, the processing process of the battery container 2, the welding process of the positive electrode lead 16 to the positive electrode current collecting member 31, and is mixed in the non-aqueous electrolyte. . Then, as in the conventional structure, when the interval between the positive electrode lead 16 and the second separator 14 adjacent to the outside thereof is widened, it is generated in each step from the widened space, and is generated in the non-aqueous electrolyte. The mixed foreign matter enters between the positive electrode 11 and the second separator 14.

  Since a predetermined potential, for example, 4.1 V, is applied between the positive electrode 11 and the negative electrode 12, foreign matter that has entered between the positive electrode 11 and the second separator 14 is ionized and penetrates the separator. It flows to the negative electrode 12 side. Then, it grows and deposits on the negative electrode 12 and is deposited. This deposit causes a phenomenon in which the positive electrode and the negative electrode are short-circuited.

  Therefore, in the cylindrical secondary battery of the present invention, as shown in FIG. 4, the first separator 13 and the second separator that are located above the end of the negative electrode mixture 12 b of the negative electrode 12 on the upper side. The end portion (upper side end portion) of the separator 14 is inclined toward the positive electrode current collecting member 31 side together with the positive electrode mixture untreated portion 11 c of the positive electrode 11. Since the upper end portion of the second separator 14 is inclined toward the positive electrode current collecting member 31 side, the upper portion of the positive electrode 11 is covered with the upper end portion of the second separator 14 adjacent to the outside. .

  Thus, in the cylindrical secondary battery of the present invention, the upper end of the second separator 14 adjacent to the outside of the positive electrode 11 is inclined toward the positive current collecting member 31 side, and the upper part of the positive electrode Therefore, the gap between the positive electrode 11 and the second separator 14 is narrowed. For this reason, it can prevent that the foreign material which causes an internal short circuit from entering between the positive electrode sheet 11a and the 2nd separator 14 enters.

Next, as shown in FIG. 4, the positive electrode lead 16 is connected to the positive electrode current collector 16 with the upper end portions of the first separator 13 and the second separator 14 inclined toward the positive electrode current collecting member 31 side. A method for joining the member 31 will be described.
FIG. 5 is an enlarged cross-sectional view showing a state before the positive electrode lead 16 of the positive electrode 11 is joined to the positive electrode current collecting electrode 31, and FIG. 6 is an upper side end of the first separator 13 and the second separator 14. It is an expanded sectional view for demonstrating the method which inclines a part toward the positive electrode current collection member 31 side.

  In the electrode group 10, a first separator 13, a positive electrode 11, a second separator 14, and a negative electrode 12 are laminated in this order around a shaft core 15 and wound. The outermost periphery is the negative electrode 12 and the first separator 13 wound around the outer periphery. The outermost periphery may be the second separator 14.

  Before connecting the positive electrode lead 16 of the positive electrode 11 to the positive electrode current collecting member 31, the first separator 13, the positive electrode 11, the second separator 14, and the negative electrode 12 are connected to a shaft core 15 as shown in FIG. Are aligned parallel to the axial direction. In the state of FIG. 5, the width A of the portion above the upper end surface of the negative electrode mixture 12b in the first separator 13 or the second separator 14 is about 2 mm. Further, the width B of the portion above the upper end surface of the positive electrode mixture 11b in the negative electrode 12 is about 2 mm.

  In FIG. 5, the width A portion of the first separator 13 and the second separator is inclined toward the positive electrode current collecting member 31 using a shaping jig 53 having a cylindrical hollow portion 51 on the inside. .

  FIG. 7 is a perspective view of the shaping jig 53, and FIG. 8 is a perspective view of the shaping jig 53 divided into divided pieces. The shaping jig 53 has a thin cylindrical shape having a hollow cross section, and has a pressing portion 52 formed of an elastic body on the inside. The shaping jig 53 includes three divided pieces 53a, 53b, and 53c. As shown in FIG. 8, each divided piece 53a to 53c has two alignment surfaces 54 that are parallel to the axial direction. ing. That is, one ring-shaped shaping jig 53 centering on the central axis is configured by bringing the split pieces 53a, 53b, 53c together and bringing the surface 54 into contact with each other.

  Each split piece 53a, 53b, 53c is attached to each of the mating surfaces 54 on three movable mounting portions of the crimping apparatus (not shown) with the inner surface 51 of the pressing portion 52 facing the positive electrode current collecting member 31 side. Are attached in a state of being separated from each other. Then, the width A portion of the first separator 13 and the second separator in the state illustrated in FIG. 5 is pressed by the inner surface 51 of the pressing portion 52 of each divided piece 53a, 53b, 53c. That is, the divided pieces 53a, 53b, 53c are moved toward the central axis, in other words, in the direction of the arrow in FIG. 6 until the mating surfaces 54 of the divided pieces 53a, 53b, 53c are in close contact with each other. By doing so, as shown in FIG. 6, the first separator 13 and the second separator 14 are positioned above the upper end of the negative electrode mixture 12 b of the negative electrode 12. The end portion is inclined toward the positive electrode current collecting member 31 side together with the positive electrode mixture untreated portion 11c of the positive electrode 11.

The positive electrode lead 16 of the positive electrode 11 is connected to the positive electrode current collector in a state where the upper end portions of the first separator 13 and the second separator 14 are inclined toward the positive electrode current collecting member 31 side by the shaping jig 53. The member 31 is closely attached to the outer surface of the upper cylindrical portion 31c. This state is illustrated in FIG. In this state, the pressing member 32 is wound around the outer periphery of the positive electrode lead 16. Then, the positive electrode lead 16 and the presser ring 32 are welded to the upper cylindrical portion 31 c of the positive electrode current collecting member 31 by ultrasonic welding or the like.
Thereafter, the divided pieces 53a to 53c of the shaping jig 53 are moved in directions away from each other.

In this way, as shown in FIG. 4, the upper side end of the second separator 14 adjacent to the outside of the positive electrode 11 can cover the upper part of the positive electrode 11. For this reason, as described above, the interval between the positive electrode 11 and the second separator 14 is narrowed, and foreign matter that causes an internal short circuit is prevented from entering from the interval between the positive electrode 11 and the second separator 14. can do.
Next, an example of a method for manufacturing the cylindrical secondary battery having the above configuration will be described.

-Manufacturing method of cylindrical secondary battery-
A positive electrode 11 is produced in which a positive electrode mixture 11b and a positive electrode mixture untreated portion 11c are formed on both surfaces of the positive electrode sheet 11a, and a large number of positive electrode leads 16 are integrally formed on the positive electrode sheet 11a. Moreover, the negative electrode mixture 12b and the negative electrode process part 12c are formed in both surfaces of the negative electrode sheet 12a, and the negative electrode 12 by which many negative electrode leads 17 were integrally formed in the negative electrode sheet 12a is produced.

  Then, as illustrated in FIG. 3, the electrode group 10 is manufactured by winding the first separator 13, the positive electrode 11, the second separator 14, and the negative electrode 12 in this order on the shaft core 15. In this case, the first separator 13, the positive electrode 11, the second separator 14, and the negative electrode 12 are resistant to the load applied during winding if the innermost side edge is welded to the shaft core 15. It is easy to turn.

  A negative electrode current collecting member 21 is attached to the lower portion of the shaft core 15 of the electrode group 10. The negative current collector 21 is attached by fitting the opening 21 b of the negative current collector 21 into a step portion 15 b provided at the lower end of the shaft 15. Next, the negative electrode lead 17 is distributed almost uniformly around the entire outer periphery of the outer peripheral cylindrical portion 21 c of the negative electrode current collecting member 21, and the pressing member 22 is wound around the outer periphery of the negative electrode lead 17. Then, the negative electrode lead 17 and the presser ring 22 are welded to the negative electrode current collecting member 21 by ultrasonic welding or the like. Next, the negative electrode energizing lead 23 straddling the lower end surface of the shaft core 15 and the negative electrode current collecting member 21 is welded to the negative electrode current collecting member 21.

Next, the lower cylindrical portion 31 b of the positive electrode current collecting member 31 of the shaft core 15 is fitted into a groove 15 a provided on the upper end side of the shaft core 15. And as mentioned above, using the shaping jig 53,
In the first separator 13 and the second separator 14, the end located above the end on the upper side of the negative electrode mixture 12 b of the negative electrode 12 is combined with the positive electrode mixture untreated portion 11 c of the positive electrode 11. Then, it is inclined toward the positive electrode current collecting member 31 side.

This method is performed by pressing the upper end portions of the first separator 13 and the second separator 14 using the shaping jig 53 as described above. In this state, the positive electrode lead 16 of the positive electrode 11 is brought into close contact with the outer surface of the upper cylindrical portion 31 c of the positive electrode current collecting member 31. Then, the holding member 32 is wound around the outer periphery of the positive electrode lead 16, and the positive electrode lead 16 and the holding ring 32 are welded to the upper cylindrical portion 31c of the positive electrode current collecting member 31 by ultrasonic welding or the like.
After the positive electrode lead 16 is welded to the upper cylindrical portion 31c of the positive electrode current collecting member 31, the shaping jig 53 is removed. In this way, the power generation unit 20 is configured.

Next, the power generation unit 20 produced through the above-described steps is accommodated in a metal bottomed cylindrical member having a size that can accommodate the power generation unit 20. The bottomed cylindrical member is the battery container 2. Hereinafter, in order to simplify and clarify the description, this bottomed cylindrical member will be described as the battery container 2.
The negative electrode conducting lead 22 of the power generation unit 20 housed in the battery container 2 is welded to the battery container 2 by resistance welding or the like. In this case, although not shown, the electrode rod is inserted into the hollow shaft of the shaft core 15 from the outside of the battery case 2, and the negative electrode conducting lead 22 is pressed against the bottom of the battery case 2 by the electrode rod and welded.

Next, a part of the upper end portion side of the battery container 2 is drawn and protrudes inward to form a substantially V-shaped groove 2a on the outer surface.
The groove 2 a of the battery container 2 is formed so as to be positioned in the upper end portion of the power generation unit 20, in other words, in the vicinity of the upper end portion of the positive electrode current collecting member 31.
Next, a predetermined amount of non-aqueous electrolyte is injected into the battery container 2 in which the power generation unit 20 is accommodated.

  On the other hand, the upper lid 3 is fixed to the diaphragm 37. The diaphragm 37 and the upper lid 3 are fixed by caulking or the like. As shown in FIG. 2, since the side wall 37 b of the diaphragm 37 is initially formed perpendicular to the base portion 37 a, the peripheral edge portion 3 a of the upper lid 3 is disposed in the side wall 37 b of the diaphragm 37. Then, the side wall 37b of the diaphragm 37 is deformed by a press or the like so as to cover the upper and lower surfaces and the outer peripheral side surface of the peripheral portion of the upper lid 3 and press-contact.

  Further, the connection plate 35 is fitted and attached to the opening 41 a of the insulating plate 41. And the projection part 35a of the connection board 35 is welded to the bottom face of the diaphragm 37 with which the upper cover 3 was fixed. As the welding method in this case, resistance welding or friction diffusion bonding can be used. By welding the connection plate 35 and the diaphragm 37, the lid unit in which the insulating plate 41 into which the connection plate 35 is fitted and the upper lid 3 fixed to the connection plate 35 is integrated with the connection plate 35 and the diaphragm 37 is configured. The

  Next, one end of the connection member 33 is welded to the base 31a of the positive electrode current collector 31 by, for example, ultrasonic welding or the like. Then, a lid unit in which the upper lid 3, the diaphragm 37, the connection plate 35 and the insulating plate 41 are integrated is arranged close to the other end portion of the connection member 33. Then, the other end of the connection member 33 is welded to the lower surface of the connection plate 35 by laser welding. This welding is performed such that the joint surface with the connection plate 35 at the other end of the connection member 33 is the same as the joint surface of one end of the connection member 33 welded to the positive electrode current collector 31.

  Next, the gasket 43 is accommodated on the groove 2 a of the battery container 2. As shown in FIG. 2, the gasket 43 in this state has a structure having an outer peripheral wall 43b perpendicular to the base 43a above the ring-shaped base 43a. With this structure, the gasket 43 remains inside the upper portion of the groove 2 a of the battery container 2. The gasket 43 is formed of rubber and is not intended to be limited, but an example of one preferred material is ethylene propylene copolymer (EPDM). For example, when the battery container 2 is made of carbon steel having a thickness of 0.5 mm and the outer diameter is 40 mmΦ, the thickness of the gasket 43 is about 10 mm.

  Next, a lid unit in which the upper lid 3, the diaphragm 37, the connection plate 35, and the insulating plate 41 are integrated is disposed on the cylindrical portion 43 c of the gasket 43. Specifically, the diaphragm 37 of the lid unit is placed with the peripheral edge thereof corresponding to the cylindrical portion 43 c of the gasket 43. In this case, the upper cylindrical portion 31 c of the positive electrode current collecting member 31 is fitted to the outer periphery of the side portion 41 b of the insulating plate 41.

In this state, the diaphragm 37 is fixed to the battery container 2 together with the gasket 43 by a so-called caulking process in which a portion between the groove 2a and the upper end surface of the battery container 2 is compressed by pressing.
Thereby, the diaphragm 37, the upper lid 3, the connection plate 35, and the insulating plate 41 are fixed to the battery container 2 via the gasket 43, and the positive electrode current collecting member 31 and the upper lid 3 are connected to the connection member 33, the connection plate 35, and the diaphragm 37. Thus, the cylindrical secondary battery shown in FIG. 1 is produced.

(Modification)
In the above embodiment, the first separator 13 and the second separator 14 are positioned on the upper side of the negative electrode mixture 12b of the negative electrode 12, that is, the portion of the width A in FIG. The structure is inclined toward the side.
In the modification shown in FIG. 10, the first separator 13 and the second separator 14 are arranged on the upper side of the positive electrode mixture 11 b of the positive electrode 11, that is, including the portion of the width B in FIG. 5. The structure is inclined toward the electric member 31 side.

In this case, the negative electrode mixture 12b of the negative electrode 12 also has a structure inclined toward the positive electrode current collecting member 31 side. For this reason, it is necessary to take care not to damage the negative electrode mixture 12b, but when the difference between the width of the first separator 13 or the second separator 14 and the width of the negative electrode mixture 12b of the negative electrode 12 is small. That is, it is effective when the width A in FIG. 5 is small.
Other configurations in FIG. 10 are the same as those in the embodiment, and thus the same components are denoted by the same reference numerals and description thereof is omitted.

  As described above, the cylindrical secondary battery of the present invention has a structure in which the upper end of the second separator 14 adjacent to the outside of the positive electrode 11 covers the upper side of the positive electrode 11. For this reason, the space | interval of the positive electrode 11 and the 2nd separator 14 becomes narrow, and it can prevent that the foreign material which causes an internal short circuit enters from the space | interval of the positive electrode 11 and the 2nd separator 14. .

  In each of the above embodiments, the width A or the entire width A and width B of the first separator 13 and the second separator 14 has been described as being inclined toward the positive electrode current collecting member 31 side. Only a part on the upper side or a part on the upper side of the width B may be inclined toward the positive electrode current collecting member 31 side.

  The shaping jig 53 is configured by the three divided pieces 53a to 53c, but the number of the divided pieces is not limited, and may be configured by a plurality of divided pieces. Moreover, the shaping jig | tool 53 should just be a cylindrical shape in the inner hollow part, and an outer peripheral shape is good also as a polygonal shape.

  In each of the above embodiments, the lithium secondary battery has been described as an example of the cylindrical secondary battery. However, the present invention is not limited to the lithium battery, and other cylindrical types such as a nickel hydride battery and a nickel cadmium battery. It can also be applied to a secondary battery.

  In addition, the cylindrical secondary battery of the present invention can be variously modified and configured within the scope of the invention. In short, the first separator and the positive electrode sheet are arranged around the shaft core. A positive electrode having a positive electrode mixture formed on both sides, an electrode group in which a negative electrode having a negative electrode mixture formed on both surfaces of the second separator and the negative electrode sheet is wound, and arranged on the upper side in the axial direction of the shaft core And a positive electrode current collector member, wherein the positive electrode is integrally formed on the positive electrode sheet, and has a plurality of positive electrode leads connected to the positive electrode current collector member. The upper-side end portion of the first separator and the upper-side end portion of the second separator located at the outer periphery and at least on the upper side of the negative electrode mixture formed on the negative electrode sheet are on the positive electrode current collecting member side It may be anything that is inclined toward.

  In addition, the method for manufacturing a cylindrical secondary battery according to the present invention includes a first separator, a positive electrode mixture formed on both surfaces of the positive electrode sheet, and a positive electrode sheet along one side of the positive electrode sheet. Winding a positive electrode having a plurality of integrally formed positive leads, a second separator, and a negative electrode having a negative electrode mixture formed on both sides of the negative electrode sheet to form an electrode group; A step of attaching a positive electrode current collector to the upper part of the shaft core; and an upper side end of the first separator located on the outer periphery of at least the negative electrode mixture provided on the negative electrode sheet And a step of inclining the upper side end of the second separator toward the positive electrode current collector member and a step of connecting a plurality of positive electrode leads of the positive electrode sheet to the positive electrode current collector member Good.

DESCRIPTION OF SYMBOLS 1 Cylindrical secondary battery 2 Battery container 3 Upper cover 10 Electrode group 11 Positive electrode 11a Positive electrode sheet 11b Positive electrode mixture 12 Negative electrode 12a Negative electrode sheet 12b Negative electrode mixture 13 1st separator 14 2nd separator 15 Axis core 16 Positive electrode lead 17 Negative electrode lead 20 Power generation unit 21 Negative electrode current collecting member 31 Positive electrode current collecting member 31c Upper cylindrical portion of positive electrode current collecting member 33 Connecting member 35 Connecting plate 37 Diaphragm 41 Insulating plate 43 Gasket 53 Shaping jig 53a, 53b, 53c Split piece

Claims (7)

Around the shaft core, the first separator, the positive electrode having the positive electrode mixture formed on both sides of the positive electrode sheet, and the negative electrode having the negative electrode mixture formed on both sides of the second separator and the negative electrode sheet were wound. A plurality of electrode groups and a positive electrode current collector member disposed on an upper side in the axial direction of the shaft core, wherein the positive electrode is formed integrally with the positive electrode sheet and connected to the positive electrode current collector member A cylindrical secondary battery having a positive electrode lead of
An upper-side end portion of the first separator and an upper-side end portion of the second separator that are located on the outer periphery from the positive electrode current collector and at least on the upper side of the negative electrode mixture formed on the negative electrode sheet Is inclined toward the positive electrode current collecting member side.   2. The cylindrical secondary battery according to claim 1, wherein an upper side end portion of the negative electrode sheet located on an upper side of the negative electrode mixture in the separator on the outermost periphery of the electrode group faces toward the positive electrode current collecting member. A cylindrical secondary battery characterized by being inclined.   3. The cylindrical secondary battery according to claim 1, wherein a portion of the first separator and the second separator that is located below the negative electrode mixture is parallel to the shaft core. The cylindrical secondary battery is not inclined toward the positive electrode current collector member side. A positive electrode having a first separator, a positive electrode mixture formed on both surfaces of the positive electrode sheet, and a plurality of positive leads integrally formed on the positive electrode sheet along one side of the positive electrode sheet, around the shaft core Winding the negative electrode having the negative electrode mixture formed on both sides of the second separator and the negative electrode sheet to form an electrode group;
Attaching a positive current collector to the upper part of the shaft core of the electrode group;
An upper-side end portion of the first separator and an upper-side end portion of the second separator that are located on the outer periphery of the positive electrode current collector and at least on the upper side of the negative electrode mixture provided on the negative electrode sheet Inclining toward the positive electrode current collector member side,
Connecting a plurality of positive leads of the positive electrode sheet to the positive current collector;
The manufacturing method of the cylindrical secondary battery characterized by including.   5. The method for manufacturing a cylindrical secondary battery according to claim 4, wherein the upper side end portion of the first separator and the upper side end portion of the second separator are inclined toward the positive electrode current collector member side. Moves a shaping jig having a cylindrical hollow portion from the outermost periphery of the electrode group to the positive electrode current collector member side, and moves the upper side end of the first separator and the upper side of the second separator The manufacturing method of the cylindrical secondary battery characterized by including the process of pressurizing an edge part.   6. The method of manufacturing a cylindrical secondary battery according to claim 5, wherein the step of connecting the plurality of positive electrode leads of the positive electrode sheet to the positive electrode current collecting member is performed by an upper part of the first separator by the shaping jig. A method for producing a cylindrical secondary battery, which is performed in a state where the side end portion and the upper side end portion of the second separator are pressurized. In the manufacturing method of the cylindrical secondary battery of any one of Claim 5 or 6,
The shaping jig having the cylindrical hollow portion is moved from the outermost periphery of the electrode group to the positive electrode current collector member side, and the upper side end of the first separator and the upper side end of the second separator The step of pressurizing the portion includes a step of moving a plurality of divided pieces each having a mating surface parallel to the axial direction toward the axial direction of the hollow portion of the cylindrical shape. A method for manufacturing a secondary battery.

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