JP2007265846A - Cylindrical battery and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylindrical battery having low internal resistance by adopting welding structure capable of stably welding a current collector to a core exposed part. <P>SOLUTION: The cylindrical battery is formed by housing an electrode body in which a positive current collector 14 is welded to a positive electrode core exposed part 11c of a rolled electrode group and a negative current collector is welded to a negative electrode core exposed part in an outer packaging can. The current collector 14 has a central opening 14b and almost U-shaped grooves 14c radially formed from the central opening 14b, the core exposed part 11c has a plurality of bent grooves 11d bent along a pair of slits in parallel each other toward the center direction of a spiral, the almost U-shaped grooves 14c are formed on the bent grooves 11d, the contact surface between outer bottom surfaces of the almost U-shaped grooves 14d and the bent grooves 11d is welded, and the contact surface between a standing part 11e remaining in the core exposed part 11c by the formation of the bent grooves 11d and the side wall of the almost U-shaped groove 14c is welded. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cylindrical battery such as a lithium secondary battery or an alkaline storage battery, and more particularly, a positive electrode current collector is welded to a positive electrode core exposed portion formed at one end of a spiral electrode group, and the spiral electrode The present invention relates to a cylindrical battery having an electrode body in which a negative electrode current collector is welded to a negative electrode core exposed part formed at the other end of the group in a cylindrical outer can and a method for manufacturing the same.

  In recent years, energy density (Wh / Kg) has been used as a power source for portable electronic / communication devices such as mobile phones, notebook computers, and small video cameras, or as a power source for hybrid vehicles (HEV) and electric vehicles (EV). Cylindrical batteries such as high lithium secondary batteries are attracting attention.

  This type of cylindrical lithium secondary battery is generally manufactured as follows. That is, first, a positive electrode mixture containing a positive electrode active material is applied to a positive electrode core (usually an aluminum foil) to produce a strip-like positive electrode plate, and a negative electrode active material is applied to the negative electrode core (usually a copper foil). A negative electrode mixture containing is applied to produce a strip-shaped negative electrode plate. Thereafter, the obtained belt-like positive electrode plate and the belt-like negative electrode plate are laminated so as to face each other via a belt-like separator, and these are wound spirally to form a spiral electrode group. After that, the core exposed portion (the uncoated portion of the positive electrode mixture) at the end of the positive electrode plate of the spiral electrode group and the positive electrode current collecting tab are welded, and the core exposed portion (the negative electrode mixture) at the end of the negative electrode plate. The electrode body is welded to the negative electrode collector tab. The electrode body produced in this way is housed in a cylindrical outer can, and after pouring a nonaqueous electrolyte, it is sealed with a sealing body to form a cylindrical battery.

  Here, when welding the core exposed portion and the positive electrode current collecting tab (or the negative electrode plate end core exposed portion and the negative electrode current collecting tab) at the end of the positive electrode plate of the spiral electrode group, A pair of parallel slits are formed, and the electrode plate end portion of the portion partitioned by the slits is bent to form an electrode surface inward of the side end surface of the spiral electrode group. Patent Document 1 proposes welding a tab. In the spiral electrode group 20 shown in Patent Document 1 described above, as shown in FIG. 7, a positive electrode core exposed portion 21a extending from the positive electrode plate is formed at one end and the other end is formed. A negative electrode core exposed portion 22a extending from the negative electrode plate is formed at the end.

The positive electrode current collecting tabs 22, 23, 24, and 25 made of four rectangular plates are welded to the upper surface of the positive electrode core exposed portion 21 a, and the lower surface of the negative electrode core exposed portion also has a positive electrode. A negative electrode current collecting tab (not shown) substantially similar to the current collecting tab is welded. Since welding of the negative electrode current collecting tab is similar to welding of the positive electrode current collecting tab, only the welding of the positive electrode current collecting tab will be described below. Here, when the four positive current collecting tabs 22, 23, 24, 25 are welded to the upper surface of the positive electrode core exposed portion 21a, the four positive current collecting tabs 22, 23 are disposed on the upper surface of the positive electrode core exposed portion 21a. , 24, 25 are arranged, and laser light is irradiated on these positive electrode current collecting tabs 22, 23, 24, 25 to attach the respective positive electrode current collecting tabs 22, 23, 24, 25 to the positive electrode core exposed portion 21a. We are trying to weld.
JP 2000-40502 A

However, as shown in Patent Document 1 described above, in the method of arranging four current collecting tabs on the core exposed portion and irradiating these current collecting tabs with laser, the number of parts is reduced. Therefore, the welding method is complicated and the handling is troublesome, and the workability is also poor, so that the production efficiency is lowered.
In addition, since only the contact surface between the bottom surface of each current collecting tab and the core exposed portion is welded by laser, the contact resistance between each current collecting tab and the core exposed portion becomes relatively large, and the internal resistance Has a relatively large voltage drop when used for high current applications, resulting in a problem that the operating voltage decreases.
Accordingly, the present invention has been made to solve the above-described problems, and adopts a welding structure that can stably weld the current collector to the core body exposed portion, thereby reducing the internal resistance. An object of the present invention is to provide a battery and a method for manufacturing a cylindrical battery that is easy to manufacture and has improved production efficiency.

  In the cylindrical battery of the present invention, the positive electrode current collector is welded to the positive electrode core exposed portion formed at one end of the spiral electrode group, and the negative electrode core exposed at the other end of the spiral electrode group is exposed. An electrode body having a negative electrode current collector welded to a portion is provided in a cylindrical outer can. In order to achieve the above object, the current collector includes a central opening and a plurality of substantially U-shaped grooves formed radially from the central opening, and the core body exposed part is formed in the core body exposed part. A plurality of bent grooves formed by bending toward the center of the spiral along a pair of mutually parallel slits are provided. And the substantially U-shaped groove part formed in the current collector is disposed on the bent groove part, and the contact surface between the outer bottom surface of the substantially U-shaped groove part and the bent groove part is welded, Due to the formation of the bent groove portion, the contact surface between the standing portion remaining in the core exposed portion and the side wall of the substantially U-shaped groove portion is welded.

  In this way, the substantially U-shaped groove portion formed on the current collector is disposed on the bent groove portion, and the contact surface between the outer bottom surface of the substantially U-shaped groove portion and the bent groove portion is welded, When the contact surface between the standing part remaining in the core exposed part and the side wall of the substantially U-shaped groove is welded by forming the bent groove, the substantially U-shaped formed on the current collector A stable weld can be formed on each contact surface between the groove and the core exposed portion. As a result, a welded structure capable of reducing the internal resistance can be obtained. In this case, considering the ease of manufacture, the substantially U-shaped grooves formed in the current collector are formed in four directions perpendicular to each other from the central opening, and the bent grooves are perpendicular to each other from the center of the spiral. It is desirable that the four directions are formed.

  In order to manufacture a cylindrical battery having a current collecting structure as described above, a slit forming step of forming a plurality of pairs of slits radially parallel to each other from the center of the spiral in the core exposed portion, A bent groove forming step of forming a bent groove portion by bending the core exposed portion along a pair of slits parallel to the spiral toward the center of the spiral, and a current collector formed on the bent groove portion 1st welding which irradiates an energy ray on the bottom face of the said substantially U-shaped groove part, and welds the contact surface of the said substantially U-shaped groove part and the said bending groove part after arrange | positioning a substantially U-shaped groove part. And a second welding step of irradiating energy rays to the side wall of the substantially U-shaped groove and welding the contact surface between the side wall of the substantially U-shaped groove and the standing portion remaining in the core exposed portion, Should be provided. In addition, although an electron beam and a laser beam can be used as an energy beam, it is desirable to use a laser beam from a viewpoint of ease of manufacture.

  In the cylindrical battery of the present invention, since the current collector has a welded structure that can be stably welded to the core exposed portion, it is possible to obtain a cylindrical battery with reduced internal resistance. In addition, it is possible to manufacture a cylindrical battery that is easy to manufacture and has improved production efficiency.

  Next, an embodiment of the present invention will be described below with reference to FIGS. 1 to 6. However, the present invention is not limited to this embodiment, and may be appropriately changed without changing the object of the present invention. Can be implemented. FIG. 1 is a perspective view schematically showing a state in which a spiral electrode group is wound and manufactured. FIG. 2 is a top view schematically showing the state of the produced spiral electrode group as viewed from the upper surface, FIG. 2 (a) shows the spiral electrode group immediately after production, and FIG. 2 (b) shows the spiral electrode. FIG. 2 (c) shows a state in which a pair of parallel slits (cuts) are formed in the core exposed portion extending from the electrode plate of the group, and FIG. 2 (c) shows the core exposed portion partitioned by the pair of parallel slits. The state which bent and formed the bending groove part is shown. FIG. 3 is a diagram schematically showing a state in which a positive electrode current collector is welded to the spiral electrode group of the present invention.

  FIG. 4 is a diagram schematically showing a state in which the bottom surface and the side surface of the substantially U-shaped groove of the positive electrode current collector are welded to the spiral electrode group in which the bent groove portion is formed, and FIG. FIG. 4B is a cross-sectional view showing a cross section in a direction parallel to the winding direction of the spiral electrode group in the curved groove portion, and FIG. 4B shows a cross section in a direction perpendicular to the winding direction of the spiral electrode group in the bent groove portion. It is sectional drawing. FIG. 5 is a diagram schematically showing a state in which the bottom surface of the substantially U-shaped groove of the positive electrode current collector is welded to the spiral electrode group in which the bent groove portion is formed, and FIG. FIG. 5B is a cross-sectional view showing a cross section in a direction parallel to the winding direction of the spiral electrode group at FIG. 5B, and FIG. 5B is a cross-sectional view showing a cross section in a direction perpendicular to the winding direction of the spiral electrode group in the bent groove portion. It is. FIG. 6 is a diagram schematically showing a state in which the bottom surface of the substantially U-shaped groove of the positive electrode current collector is welded to the spiral electrode group in which the bent groove portion is not formed, and FIG. It is sectional drawing which shows the cross section of the direction parallel to the winding direction of a spiral electrode group, FIG.6 (b) is sectional drawing which shows the cross section of a direction perpendicular | vertical to the winding direction of the spiral electrode group in a U-shaped groove. .

1. Positive electrode plate A positive electrode mixture was prepared by mixing 94% by mass of lithium cobaltate (LiCoO ₂ ) powder as a positive electrode active material and 3% by mass of carbon-based powder such as acetylene black or graphite as a conductive agent. This positive electrode mixture was kneaded with a binder solution prepared by dissolving 3% by mass of a binder composed of polyvinylidene fluoride (PVdF) in an organic solvent composed of N-methyl-2-pyrrolidone (NMP). An active material slurry was prepared. In addition to the above-described LiCoO ₂ , the positive electrode active material is Li _x MO ₂ (where M is at least one of Co, Ni, and Mn, and 0.45 ≦ x ≦ 1.20). Metal composite oxide, for example, LiNiO ₂ , LiNi _y Co _1-y O ₂ (where 0.01 ≦ y ≦ 0.99), Li _0.5 MnO ₂ , LiMnO _2, etc. You may make it use.

  Next, a positive electrode core 11a made of an aluminum foil (for example, having a thickness of 20 μm) is prepared, and the positive electrode active material slurry prepared as described above is uniformly applied to one surface of the positive electrode core 11a. Layer 11b was formed. In this case, on the upper side of the positive electrode mixture layer 11b, a non-applied portion (positive electrode core exposed portion) 11c having a predetermined width (here, 10 mm) where the positive electrode active material slurry is not applied is an end of the positive electrode core body 11a. It was applied so as to form along the edge. Then, it was made to pass through a drier to remove the organic solvent (NMP) that was necessary at the time of slurry preparation and to dry. After drying, it was rolled with a roll press machine to a thickness of 0.06 mm to produce a positive electrode plate. The positive electrode plate thus produced was cut into a strip shape having a width of 96 mm to obtain a positive electrode plate 11 provided with a strip-shaped positive electrode core exposed portion 11c having a width of 10 mm.

2. Negative electrode plate 98% by mass of natural graphite powder as the negative electrode active material and 1% by mass of carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR) as the binder were mixed, kneaded and mixed with water. A material slurry was prepared. As the negative electrode active material, in addition to the above-mentioned natural graphite, a carbon-based material capable of occluding and desorbing lithium ions, such as artificial graphite, carbon black, coke, glassy carbon, carbon fiber, or a fired body thereof. May be used, and the potential of lithium alloys such as metallic lithium, lithium-aluminum alloy, lithium-lead alloy, lithium-tin alloy, SnO ₂ , SnO, TiO ₂ , Nb ₂ O _3, etc. is higher than that of the positive electrode active material. A base metal oxide may be used.

  Next, a negative electrode core body 12a made of copper foil (for example, having a thickness of 12 μm) is prepared, and the negative electrode active material slurry prepared as described above is uniformly applied to one surface of the negative electrode core body 12a. Layer 12b was formed. In this case, a non-applied portion (negative electrode core exposed portion) 12c having a predetermined width (here, 8 mm) where the negative electrode active material slurry is not applied is formed below the negative electrode mixture layer 12b. Applied. Then, it was dried by passing through a dryer. After drying, it was rolled with a roll press machine to a thickness of 0.05 mm to produce a negative electrode plate. The negative electrode plate thus produced was cut into a strip shape having a width of 98 mm to obtain a negative electrode plate 12 provided with a strip-shaped negative electrode core exposed portion 12c having a width of 8 mm.

3. A spiral electrode group Next, strip separators 13 and 13 made of a polyethylene microporous film (thickness of 0.022 mm and width of 100 mm) are prepared, and the positive electrode plate 11 and the negative electrode plate 12 manufactured as described above. Were placed on the separators 13 and 13 and shifted in the width direction, and overlapped so that the center lines in the width direction coincided with each other. As a result, the positive electrode core exposed portion 11c and the negative electrode core exposed portion 12c protrude from the both end edges of the separator 13 outward. Then, after winding these in a spiral shape with a winder, the outermost periphery was taped to produce a spiral electrode group 10. In the spiral electrode group 10 manufactured in this way, the positive electrode core exposed portion 11c of the positive electrode plate 11 projects outward from one edge of the separator 13 at one end, and the other end. The negative electrode core exposed portion 12 c of the negative electrode plate 12 protrudes outward from the other edge of the separator 13.

  A cutter (not shown) is pressed against the upper surface of the positive electrode core exposed portion 11c of the spiral electrode group 10 produced as described above, and as shown in FIG. 2B, the positive electrode core exposed portion 11c is constant. A pair of slits X1, X2 and Y1, Y2 parallel to each other were formed at a depth (from the tip of the positive electrode core exposed portion 11c to the end of the separator 13, for example, 2 mm). In this case, the width of the pair of slits X1, X2 or Y1, Y2 is approximately the same as the width (outside dimension) of the substantially U-shaped groove portion 14c. It formed so that it might become. Although only the positive electrode core exposed portion 11c will be described here, the negative electrode core exposed portion 12c is the same as that of the positive electrode core exposed portion 11c.

Next, the positive electrode core exposed portion 11c partitioned by the pair of slits X1, X2 or Y1, Y2 formed as described above was bent from the outer peripheral side of the spiral electrode group 10 toward the center portion. As a result, the bent groove portion 11d is formed on the positive electrode core exposed portion 11c side of the spiral electrode group 10. In this case, the bent groove portion 11d is formed on the positive electrode core exposed portion 11c side of the spiral electrode group 10, so that the standing portions 11e of the positive electrode core exposed portion 11c are formed on both sides of the upper portion of the bent groove portion 11d. Will be formed. In addition, a bent groove portion (not shown) is also formed on the negative electrode core exposed portion 12c side of the spiral electrode group 10, and on both sides of the lower portion of the bent groove portion, a standing portion of the negative electrode core exposed portion 12c ( (Not shown) will be formed.
Here, the spiral electrode group 10 in which the bent groove portion 11d is formed is referred to as a spiral electrode group a, and the spiral electrode group 10 in which the bent groove portion 11d is not formed is referred to as a spiral electrode group b.

4). Spiral electrode body Next, a positive electrode current collector 14 was prepared. Here, as shown in FIG. 3, the positive electrode current collector 14 includes a circular flat plate-like main body portion 14a and a lead portion 14e extending from the main body portion 14a, and these are integrally formed. . The flat plate-like main body portion 14a has a central opening 14b at the center thereof, and a plurality of cross-sectional shapes extending radially from the central opening 14b. The substantially U-shaped groove portion 14c and a plurality of notes around the central opening 14b. The liquid hole 14d is provided, and these are integrally formed. In FIG. 3, only the positive electrode current collector 14 is illustrated, but the negative electrode current collector has substantially the same configuration as the positive electrode current collector 14, and thus description thereof is omitted.

  Next, the positive electrode current collector 14 is disposed on the spiral electrode group a, and the substantially U-shaped groove portion formed in the positive electrode current collector 14 is formed in the bent groove portion 11d formed on the positive electrode core body exposed portion 11c side. The substantially U-shaped groove part 14c was fitted to the bending groove part 11d.

  Next, as shown in FIG. 4A, the laser beam La was irradiated along the center of the bottom surface of the substantially U-shaped groove 14c. Thereafter, the laser beam Lb is irradiated along the central portion in the height direction of one side wall of the substantially U-shaped groove portion 14c, and further, the laser beam Lc is irradiated along the central portion in the height direction of the other side wall. did. Thereby, the 1st welding part 15a is formed in the contact surface of the bottom face of the substantially U-shaped groove part 14c, and the bending groove part 11d, and one side wall of the substantially U-shaped groove part 14c and the positive electrode core body exposed part 11c are erected. The second welded portion 15b is formed on the contact surface with the portion 11e, and the third welded portion 15c is formed on the contact surface between the other side wall of the substantially U-shaped groove portion 14c and the standing portion 11e of the positive electrode core exposed portion 11c. Will be.

  On the other hand, after fitting the substantially U-shaped groove part of the negative electrode current collector disposed under the spiral electrode group a into the bent groove part formed on the negative electrode core exposed part 12c side, The laser light La, Lb, Lc is irradiated to contact the bottom surface of the substantially U-shaped groove portion of the negative electrode current collector with the bent groove portion, one side wall of the substantially U-shaped groove portion, and the negative electrode core exposed portion 12c. A welded portion was formed on the contact surface with the upright portion and the contact surface between the other side wall of the substantially U-shaped groove and the upright portion of the negative electrode core exposed portion 12c, thereby producing an electrode body A1.

Further, the positive electrode current collector 14 is disposed on the spiral electrode group a, and the substantially U-shaped groove portion formed in the positive electrode current collector 14 is formed in the bent groove portion 11d formed on the positive electrode core body exposed portion 11c side. The substantially U-shaped groove part 14c was fitted to the bending groove part 11d. Then, as shown in FIG. 5A, the laser beam La was irradiated along the center of the bottom surface of the substantially U-shaped groove 14c. Thereby, the welding part 16a will be formed in the contact surface of the bottom face of the substantially U-shaped groove part 14c, and the bending groove part 11d.
On the other hand, after fitting the substantially U-shaped groove part of the negative electrode current collector disposed under the spiral electrode group a into the bent groove part formed on the negative electrode core exposed part 12c side, The laser beam La was irradiated to form a welded portion on the contact surface between the bottom surface of the substantially U-shaped groove portion of the negative electrode current collector and the bent groove portion, thereby producing an electrode body B1.

Furthermore, the positive electrode current collector 14 is disposed on the spiral electrode group b, and the main body portion 14a of the positive electrode current collector 14 is pressed against the positive electrode core body exposed portion 11c, so that the substantially U-shape of the positive electrode current collector 14 is obtained. The groove part 14c was made to bite into the positive electrode core exposed part 11c. Next, as shown in FIG. 6A, the laser beam La was irradiated along the center of the bottom surface of the substantially U-shaped groove 14c. Thereby, the welding part 17a will be formed in the contact surface of the bottom face of the substantially U-shaped groove part 14c, and the positive electrode core exposed part 11c.
On the other hand, after pressing the main body portion of the negative electrode current collector disposed under the spiral electrode group b, the groove of the negative electrode current collector is caused to bite into the negative electrode core body exposed portion 12c, and then, as described above, the laser Irradiated with light La, a welded portion was formed on the contact surface between the bottom surface of the substantially U-shaped groove of the negative electrode current collector and the negative electrode core exposed portion 12c, and an electrode body C1 was produced.

5). Non-aqueous electrolyte secondary battery Next, the electrode bodies A1, B1, C1 produced as described above are inserted into a cylindrical metal outer can. Thereafter, the negative electrode lead extending from the main body portion of the negative electrode current collector is spot welded to the inner surface of the bottom of the outer can, and then the positive electrode lead 14e extending from the main body portion 14a of the positive electrode current collector 14 is sealed with a sealing body (in addition, A pressure valve is provided inside the sealing body, and an insulating gasket is provided around it (not shown). Laser welding is performed on the bottom of the sealing body. Next, a nonaqueous electrolytic solution in which LiPF ₆ was dissolved as an electrolyte at a ratio of 1 mol / liter in a mixed solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 3: 7 in the outer can. After the liquid is injected, the sealing body is placed in the throttle part formed around the lower part of the opening of the outer can, and the opening of the outer can is caulked to the sealing body side to seal it, so that the cylindrical non-aqueous electrolyte solution 2 is sealed. Secondary batteries (A, B, C) are produced.

Here, a battery using the electrode body A1 was designated as a battery A, a battery using the electrode body B1 was designated as a battery B, and a battery using the electrode body C1 was designated as a battery C. As the electrolyte, in addition to the above-described lithium hexafluorophosphate (LiPF ₆ ), lithium perchlorate (LiClO ₄ ), lithium borofluoride (LiBF ₄ ), lithium hexafluorosilicate (LiAsF ₆ ), trifluoro A lithium salt such as lithium methyl sulfonate (LiCF ₃ SO ₃ ) or lithium bistrifluoromethylsulfonylimide (LiN (CF ₃ SO ₂ ) ₂ ) may be used. In addition, the amount dissolved in the organic solvent is not limited to 1 mol / liter, but is preferably 0.5 to 2.0 mol / liter.

Using the batteries A, B, and C produced as described above, the internal resistance of each of the batteries A, B, and C is measured by measuring the AC impedance of each of the batteries A, B, and C at a frequency of 1 kHz. When (mΩ) was obtained, the results shown in Table 1 below were obtained.

As is apparent from the results in Table 1, the battery C has a large internal resistance of 0.81 mΩ. In the battery C, by pressing the main body portion 14a of the positive electrode current collector 14 against the positive electrode core exposed portion 11c, the substantially U-shaped groove portion 14c formed in the positive electrode current collector 14 is changed to the positive electrode core exposed portion. 11c is bitten. For this reason, the contact between the positive electrode core exposed portion 11c and the bottom surface of the substantially U-shaped groove portion 14c formed in the positive electrode current collector 14 is not sufficient, and a sufficient welded portion 17a is not formed on these contact surfaces. Conceivable.
Further, when the substantially U-shaped groove portion 14c is made to bite into the positive electrode core exposed portion 11c, as shown in FIG. 6 (b), a gap Z (a circle in FIG. 6 (b)) is formed between the positive electrode core exposed portions 11c. When the laser beam La is irradiated in this state, the laser beam La penetrates the bottom wall of the groove 14c and enters the gap Z. Thereby, the malfunction that a welding dust scatters in an electrode body and a short circuit arises arises.

  On the other hand, the battery B has an internal resistance of 0.77 mΩ, which indicates that the internal resistance is improved compared to the battery C. In the battery B, since the welded portion 16a is formed on the contact surface between the bottom surface of the substantially U-shaped groove portion 14c and the bent groove portion 11d, the positive electrode core body exposed portion 11c and the substantially U-shaped groove portion 14c Good contact with the bottom surface. Thereby, it is considered that the welded portion 16a between the positive electrode core body exposed portion 11c and the bottom surface of the groove 14c in the bent groove portion 11d is stabilized, and the internal resistance is reduced. In this case, since the end portion of the positive electrode core exposed portion 11c is bent to form the bent groove portion 11d, the laser light La does not penetrate the groove 14c and enter the electrode body.

  On the other hand, the battery A has an internal resistance of 0.75 mΩ, which indicates that the internal resistance is further improved than the batteries C and B. In the battery A, the first welded portion 15a is formed on the contact surface between the bottom surface of the substantially U-shaped groove portion 14c and the bent groove portion 11d, and one side wall of the substantially U-shaped groove portion 14c and the positive electrode core body are exposed. A second welded portion 15b is formed on the contact surface of the portion 11c with the standing portion 11e, and a third surface is formed on the contact surface between the other side wall of the substantially U-shaped groove portion 14c and the standing portion 11e of the positive electrode core exposed portion 11c. Since the welded portion 15c is formed, the positive electrode core exposed portion 11c and the contact between the bottom surface and the side surface of the substantially U-shaped groove portion 14c are improved. Thereby, the 1st weld part 15a, the 2nd weld part 15b, and the 3rd weld part 15c came to be formed stably, and it is thought that internal resistance fell further.

  As described above, in the cylindrical battery according to the present invention, since the current collector is stably welded to the core exposed portion, the cylindrical battery with reduced internal resistance is provided. It is possible to obtain a cylindrical battery that can be easily obtained and that is easy to manufacture and has improved production efficiency.

  In the above-described embodiment, the example in which the positive electrode current collector and the negative electrode current collector are welded to both ends of the spiral electrode group by irradiating the laser beam has been described. Thus, it is obvious that welding may be performed by irradiating an electron beam or other energy beam. In the above-described embodiment, the example in which the present invention is applied to a non-aqueous electrolyte secondary battery has been described. However, the cylindrical battery of the present invention is not limited to a non-aqueous electrolyte secondary battery. A nickel-hydrogen storage battery, a nickel-metal hydride battery, a nickel-hydrogen storage battery, a nickel battery, etc. -Clearly applicable to alkaline storage batteries such as cadmium storage batteries and other storage batteries.

It is a perspective view which shows typically the state produced by winding a spiral electrode group. FIG. 2A is a top view schematically showing a state of the produced spiral electrode group as viewed from the upper surface, FIG. 2A shows the spiral electrode group immediately after production, and FIG. 2B is an electrode of the spiral electrode group. FIG. 2 (c) shows a state in which a pair of parallel slits (cuts) are formed in the core exposed portion extending from the plate, and FIG. 2 (c) folds and folds the core exposed portion partitioned by the pair of parallel slits. The state which formed the curved groove part is shown. It is a figure which shows typically the state which welds a positive electrode electrical power collector to the spiral electrode group of this invention. FIG. 4A is a diagram schematically illustrating a state in which the bottom surface and the side surface of the substantially U-shaped groove of the positive electrode current collector are welded to the spiral electrode group in which the bent groove portion is formed. FIG. FIG. 4B is a sectional view showing a section in a direction parallel to the winding direction of the spiral electrode group, and FIG. 4B is a sectional view showing a section in a direction perpendicular to the winding direction of the spiral electrode group at the bent groove portion. . FIG. 5A is a diagram schematically showing a state in which the bottom surface of the substantially U-shaped groove of the positive electrode current collector is welded to the spiral electrode group in which the bent groove portion is formed, and FIG. 5A is a view showing the spiral electrode in the bent groove portion. FIG. 5B is a cross-sectional view showing a cross section in a direction perpendicular to the winding direction of the spiral electrode group in the bent groove portion. FIG. 6A is a diagram schematically illustrating a state in which the bottom surface of the substantially U-shaped groove of the positive electrode current collector is welded to a spiral electrode group in which a bent groove portion is not formed. FIG. 6A is a diagram illustrating a spiral electrode group in a U-shaped groove. FIG. 6B is a cross-sectional view showing a cross section of the spiral electrode group in the U-shaped groove in a direction perpendicular to the winding direction. It is a perspective view which shows typically the state by which the positive electrode current collection tab was welded to the spiral electrode group of the prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Spiral electrode group, 11 ... Positive electrode plate, 11a ... Positive electrode core, 11b ... Positive electrode mixture layer, 11c ... Positive electrode core exposed part, 11d ... Bending groove part, 11e ... Standing part, 12 ... Negative electrode plate, 12a ... negative electrode core, 12b ... negative electrode mixture layer, 12c ... negative electrode core exposed part, 13 ... separator, 14 ... positive electrode current collector, 14a ... main body part, 14b ... central opening, 14c ... substantially U-shaped groove part, 14d ... Injection hole, 14e ... Positive electrode lead, 15a ... 1st welding part, 15b ... 2nd welding part, 15c ... 3rd welding part, 16a ... Welding part, 17b ... Welding part, La, Lb, Lc ... Laser beam , X1, X2 ... slit, Y1, Y2 ... slit, Z ... gap

Claims (5)

A positive electrode current collector is welded to the positive electrode core exposed part formed at one end of the spiral electrode group, and a negative electrode current collector is connected to the negative electrode core exposed part formed at the other end of the spiral electrode group. A cylindrical battery provided with a welded electrode body in a cylindrical outer can,
The current collector includes a central opening and a plurality of substantially U-shaped grooves formed radially from the central opening,
The core body exposed portion includes a plurality of bent groove portions formed by being bent toward the center direction of the spiral along a pair of mutually parallel slits formed in the core body exposed portion,
A substantially U-shaped groove formed on the current collector is disposed on the bent groove, and a contact surface between the outer bottom surface of the substantially U-shaped groove and the bent groove is welded. A cylindrical battery, wherein a contact surface between the standing portion remaining in the core exposed portion and the side wall of the substantially U-shaped groove is welded by forming the bent groove.   2. The cylindrical battery according to claim 1, wherein the substantially U-shaped groove is formed in four directions perpendicular to each other from the central opening.   The cylindrical battery according to claim 1, wherein the bent groove portion is formed in four directions perpendicular to each other from the center of the spiral. A positive electrode current collector is welded to a positive electrode core exposed part formed at one end of the spiral electrode group, and a negative electrode current collector is connected to a negative electrode core exposed part formed at the other end of the spiral electrode group A method of manufacturing a cylindrical battery in which a welded electrode body is accommodated in a cylindrical outer can and formed,
A slit forming step of forming a plurality of pairs of slits radially parallel to each other from the center of the spiral in the core exposed portion;
A bent groove portion forming step of forming a bent groove portion by bending the core body exposed portion toward the center direction of the spiral along the pair of mutually parallel slits;
After arranging the substantially U-shaped groove part formed in the current collector on the bent groove part, the bottom surface of the substantially U-shaped groove part is irradiated with energy rays on the bottom surface of the substantially U-shaped groove part. A first welding step of welding a contact surface with the bent groove portion;
A second welding step of irradiating the side wall of the substantially U-shaped groove with an energy beam and welding the contact surface between the side wall of the substantially U-shaped groove and the standing portion remaining in the core exposed portion. A method for producing a cylindrical battery, characterized by comprising: The method for manufacturing a cylindrical battery according to claim 4, wherein the energy beam is a laser beam.

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