JP2017004888A - Secondary battery and manufacturing method for secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery that can be more easily manufactured and a manufacturing method for the secondary battery.SOLUTION: The secondary battery according to one embodiment includes an electrode group, a terminal, a lead, and a current collection tab. The electrode group is an electrode group in which the positive electrode and the negative electrode superimposed via a separator are wound flat. The lead has a current collecting portion connected to the terminal and a welded portion protruding from the current collecting portion. The current collector tab extends from the electrode group and is welded to the lead by melting together with the welded portion in a state of being in contact with the current collecting portion and the welded portion.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a secondary battery and a method for manufacturing the secondary battery.

  In recent years, lithium ion batteries and the like have become popular as secondary batteries. The secondary battery is required to have high energy density and high durability depending on the application field. For example, a lithium ion battery includes an electrode assembly in which a laminate of a positive electrode and a negative electrode with a separator interposed therebetween is wound. A lithium ion secondary battery has a configuration in which an electrode assembly is enclosed in a battery can (exterior can) filled with an organic electrolyte.

  The secondary battery is configured such that a positive electrode and a negative electrode of an electrode assembly are connected to a positive electrode terminal and a negative electrode terminal via leads, respectively. The positive electrode and the negative electrode of the electrode assembly are connected to the lead by welding. For example, the positive electrode and the negative electrode of the electrode assembly are connected to the lead by TIG welding (Tungsten Inert Gas Arc Welding). However, since the positive electrode and the negative electrode of the electrode assembly are metal foils, they are scattered during welding, and there is a problem that they may not be correctly connected to the leads.

JP 2010-108916 A

  In order to solve the above problems, a secondary battery that can be manufactured more easily and a method for manufacturing the secondary battery are provided.

  A secondary battery according to an embodiment includes an electrode group, a terminal, a lead, and a current collecting tab. The electrode group is an electrode group in which a positive electrode and a negative electrode that are stacked via a separator are wound into a flat shape. The lead has a current collector connected to the terminal, and a weld provided so as to protrude from the current collector. The current collecting tab extends from the electrode group and is welded to the lead by being melted together with the welded portion while being in contact with the current collecting portion and the welded portion.

FIG. 1 is a diagram for explaining an example of a secondary battery according to an embodiment. FIG. 2 is a diagram for explaining an example of a partial configuration of the secondary battery according to the embodiment. FIG. 3 is a diagram for explaining an example of a partial configuration of the secondary battery according to the embodiment. FIG. 4 is a diagram for explaining an example of a partial cross-sectional configuration of the secondary battery according to the embodiment. FIG. 5 is a diagram for explaining an example of a partial cross-sectional configuration of the secondary battery according to the embodiment. FIG. 6 is a diagram for explaining another example of a partial cross-sectional configuration of the secondary battery according to the embodiment. FIG. 7 is a diagram for explaining another example of the secondary battery according to the embodiment. FIG. 8 is a diagram for explaining another example of the configuration of a partial cross section of the secondary battery according to the embodiment.

Hereinafter, description will be given with reference to the drawings.
FIG. 1 shows an example of a secondary battery 1 according to an embodiment.
The secondary battery 1 of this example includes an electrode-cap assembly 21 and an outer can 19. The electrode-cap assembly 21 includes an electrode assembly 10 and a cap assembly 20. The electrode-cap assembly 21 is formed by combining the electrode assembly 10 and the cap assembly 2.

  The electrode assembly 10 includes an electrode group 11, a positive current collecting tab 12, and a negative current collecting tab 13. Further, the electrolyte is held in the electrode group 11. The electrolyte is a nonaqueous electrolyte, for example.

  The cap assembly 20 includes a positive electrode terminal 14, a negative electrode terminal 15, a gasket 23, a cap 24, a positive electrode lead 28, a negative electrode lead 29, and the like.

  The secondary battery 1 also includes an electrode guard 32 provided so that the conductive member of the electrode-cap assembly 21 does not contact the inside of the outer can 19.

  The outer can 19 can be formed from, for example, aluminum or an aluminum alloy. As the aluminum alloy, an alloy containing an element such as manganese, iron, copper, silicon, or zinc is preferable. The plate thickness of the outer can 19 can be 1 mm or less, and more preferably 0.2 to 0.7 mm.

  The electrode assembly 10 is obtained by winding a laminate in which a positive electrode and a negative electrode are laminated via a separator therebetween into a flat shape. The positive electrode is a positive current collector excluding, for example, a strip-shaped positive current collector made of metal foil, a positive current collector tab 12 having one end parallel to the long side of the positive current collector, and at least the positive current collector tab 12 portion. A positive electrode material layer (positive electrode active material-containing layer) formed on the electric body. On the other hand, the negative electrode is, for example, except for a strip-shaped negative electrode current collector made of a metal foil, a negative electrode current collector tab 13 having one end parallel to the long side of the negative electrode current collector, and at least a portion of the negative electrode current collector tab 13. A negative electrode material layer (negative electrode active material-containing layer) formed on the negative electrode current collector. The electrode group 11 represents a portion of the electrode assembly 10 excluding the positive electrode current collecting tab 12 and the negative electrode current collecting tab 13.

  Such a positive electrode, separator, and negative electrode are such that the positive electrode current collecting tab 12 protrudes from the separator in the winding axis direction of the electrode assembly 10 and the negative electrode current collecting tab 13 protrudes from the separator in the opposite direction. Winding is performed by shifting the positions of the positive electrode and the negative electrode. By such winding, the electrode assembly 10 has a positive electrode current collecting tab 12 wound in a spiral shape from one end face and a negative electrode current collecting tab 13 wound in a spiral form from the other end face. Protruding state.

  The positive and negative current collector tabs may be made of the same material as the positive and negative electrode current collectors, but aluminum (Al), magnesium (Mg), titanium (Ti), zinc (Zn), manganese (Mn), iron ( You may form from the aluminum alloy containing the at least 1 sort (s) of element selected from the group which consists of Fe), copper (Cu), and silicon (Si).

  The cap assembly 20 is for housing the electrode assembly 10 in the outer can 19. The cap assembly 20 has a structure in which the positive electrode terminal 14, the negative electrode terminal 15, the positive electrode lead 28, and the negative electrode lead 29 are fixed to the cap 24 by caulking and are integrally formed.

  The cap 24 is a plate that covers the upper surface of the outer can 19. The cap 24 includes a hole through which the positive electrode terminal 14 passes and a hole through which the negative electrode terminal 15 passes. The cap 24 fixes the positive electrode terminal 14 and the negative electrode terminal 15 through a gasket 23 that is an insulating member installed in the hole. The cap 24 can be formed from, for example, aluminum or an aluminum alloy. As the aluminum alloy, an alloy containing an element such as manganese, iron, copper, silicon, or zinc is preferable.

  The positive electrode terminal 14 and the negative electrode terminal 15 function as terminals of the secondary battery 1 when the electrode assembly 10 and the cap assembly 20 are assembled to form the electrode-cap assembly 21. The positive terminal 14 is electrically connected to the positive current collecting tab 12 of the electrode assembly 10 via the positive lead 28. Further, the negative electrode terminal 15 is electrically connected to the negative electrode current collecting tab 13 of the electrode assembly 10 through the negative electrode lead 29.

  In the case of a lithium ion secondary battery in which a carbon-based material is used as the negative electrode active material, the positive electrode terminal 14 is generally made of aluminum or an aluminum alloy. The negative electrode terminal 15 is made of a metal such as copper, nickel, or nickel-plated iron. When lithium titanate is used as the negative electrode active material, aluminum or an aluminum alloy may be used for the negative electrode terminal 15 in addition to the above metal. When aluminum or an aluminum alloy is used for the positive electrode terminal 14 and the negative electrode terminal 15, the positive electrode current collecting tab 12, the negative electrode current collecting tab 13, the positive electrode lead 28, and the negative electrode lead 29 are made of aluminum or an aluminum alloy. Is desirable. For example, an aluminum alloy containing at least one element selected from the group consisting of Al, Mg, Ti, Zn, Mn, Fe, Cu, and Si is used.

  The positive electrode lead 28 and the negative electrode lead 29 are each formed of a conductive metal. The positive electrode lead 28 is electrically connected to the positive electrode current collecting tab 12 when the electrode assembly 10 and the cap assembly 20 are assembled. The negative electrode lead 29 is electrically connected to the negative electrode current collecting tab 13 when the electrode assembly 10 and the cap assembly 20 are assembled.

  Furthermore, the positive electrode lead 28 is electrically connected to the positive electrode terminal 14. The negative electrode lead 29 is electrically connected to the negative electrode terminal 15. That is, the positive electrode lead 28 electrically connects the positive electrode current collecting tab 12 and the positive electrode terminal 14. The negative electrode lead 29 electrically connects the negative electrode current collecting tab 13 and the negative electrode terminal 15.

  The positive electrode lead 28 is electrically connected to the positive electrode current collector tab 12 by being Tig welded to the positive electrode current collector tab 12 with the positive electrode current collector tab 12 sandwiched therebetween. Further, the negative electrode lead 29 is electrically connected to the negative electrode current collecting tab 13 by being Tig welded to the negative electrode current collecting tab 13 with the negative electrode current collecting tab 13 interposed therebetween.

  The electrode guard 32 is an insulation formed of an insulating material having a higher electrical resistance than the outer can 19, the electrode assembly 10, the positive electrode terminal 14, the negative electrode terminal 15, the cap 24, the positive electrode lead 28, and the negative electrode lead 29. It is a member. The secondary battery 1 includes an electrode guard 32 provided on the positive electrode side and an electrode guard 32 provided on the negative electrode side. The electrode guard 32 provided on the positive electrode side is formed in a shape covering the positive electrode lead 28, the positive electrode current collecting tab 12, and the like. The electrode guard 32 provided on the positive electrode side can prevent the positive electrode lead 28, the positive electrode current collecting tab 12, and the like from contacting the outer can 19. The electrode guard 32 provided on the negative electrode side is formed in a shape covering the negative electrode lead 29, the negative electrode current collecting tab 13, and the like. The electrode guard 32 provided on the negative electrode side can prevent the negative electrode lead 29, the negative electrode current collecting tab 13 and the like from coming into contact with the outer can 19.

  The electrode-cap assembly 21 includes the positive electrode current collecting tab 12, the negative electrode current collecting tab 13, the positive electrode terminal 14, the negative electrode terminal 15, the cap 24, the positive electrode lead 28, the negative electrode lead 29, and the like of the electrode assembly 10 as described above. It is formed by combining. In the secondary battery 1, the electrode-cap assembly 21, the electrode guard 32, and the like are accommodated in the outer can 19 and become ready for use.

  Hereinafter, the positive electrode, the negative electrode, the separator, and the nonaqueous electrolyte will be described.

  The positive electrode is produced, for example, by applying a slurry containing a positive electrode active material to a current collector made of an aluminum foil or an aluminum alloy foil. Although it does not specifically limit as a positive electrode active material, The oxide, sulfide, polymer, etc. which can occlude / release lithium can be used. Preferable active materials include lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium iron phosphate, and the like that can obtain a high positive electrode potential.

  The negative electrode is produced by applying a slurry containing a negative electrode active material to a current collector made of an aluminum foil or an aluminum alloy foil. The negative electrode active material is not particularly limited, and metal oxides, metal sulfides, metal nitrides, alloys, and the like that can occlude and release lithium can be used. Preferably, the lithium ion occlusion and release potential is metal lithium. It is a substance that becomes noble 0.4V or more with respect to the potential. Since the negative electrode active material having such a lithium ion storage / release potential can suppress the alloy reaction between aluminum or an aluminum alloy and lithium, it is possible to use aluminum or an aluminum alloy for a negative electrode current collector and a negative electrode related component. And For example, there are titanium oxide, lithium titanium composite oxide such as lithium titanate, tungsten oxide, amorphous tin oxide, tin silicon oxide, silicon oxide, etc. Among them, lithium titanium composite oxide is preferable. As the separator, a microporous film, a woven fabric, a non-woven fabric, a laminate of the same material or different materials among these can be used.

Examples of the material for forming the separator include polyethylene, polypropylene, ethylene-propylene copolymer, and ethylene-butene copolymer.
As the electrolytic solution, a nonaqueous electrolytic solution prepared by dissolving an electrolyte (for example, lithium salt) in a nonaqueous solvent is used. Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-butyrolactone (γ -BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran and the like. Nonaqueous solvents may be used alone or in combination of two or more. Examples of the electrolyte include lithium perchlorate (LiClO4), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium arsenic hexafluoride (LiAsF6), lithium trifluorometasulfonate ( Lithium salts such as LiCF3SO3) can be mentioned. The electrolyte may be used alone or in combination of two or more. The amount of electrolyte dissolved in the non-aqueous solvent is desirably 0.2 mol / L to 3 mol / L.

FIG. 2 shows an example of the positive electrode lead 28 before TIG welding is performed.
The positive electrode lead 28 includes a current collecting portion 28a formed in a bifurcated shape, a slit 28b formed between the bifurcated shapes, and a welded portion 28c formed on both sides of the slit 28b. Similarly to the positive electrode lead 28, the negative electrode lead 29 includes a current collecting portion 29a formed in a bifurcated shape, a slit 29b formed between the bifurcated shapes, and a welded portion 29c formed on both sides of the slit 29b. Prepare.

  The current collecting portion 28 a of the positive electrode lead 28 is fixed by caulking the positive electrode terminal 14 to the cap 24. The current collector 29 a of the negative electrode lead 29 is fixed by the negative electrode terminal 15 being caulked to the cap 24.

  The slits 28b of the positive electrode lead 28 are formed in parallel along the direction in which the positive electrode current collecting tabs 12 are bundled when the electrode assembly 10 and the cap assembly 20 are assembled. In other words, the slit 28b is formed in such a shape that the bundled positive electrode current collecting tabs 12 can be easily sandwiched. The slit 28b is provided with a width equal to or greater than the thickness of the bundled positive electrode current collecting tabs 12.

  The slit 29b of the negative electrode lead 29 is formed in parallel along the direction in which the negative electrode current collecting tabs 13 are bundled when the electrode assembly 10 and the cap assembly 20 are assembled. That is, the slit 29b is formed in such a shape that the bundled negative electrode current collecting tabs 13 can be easily sandwiched. The slits 29b are provided with a width equal to or greater than the thickness of the bundled negative electrode current collecting tabs 13.

  FIG. 3 shows an example of the positive electrode lead 28 when the positive electrode current collecting tab 12 is sandwiched in the slit 28b. Although the negative electrode lead 29 side is not shown, the illustration is omitted because it has the same configuration as the positive electrode lead 28 side.

  The welding part 28c is used as a metal to be welded for welding the positive electrode current collecting tab 12 and the current collecting part 28a sandwiched between the slits 28b. The welded portion 28c is formed integrally with the current collecting portion 28a, for example. The welded portion 28c is provided so as to protrude in the winding axis direction of the electrode group 11 from a surface located on the opposite side to the electrode group 11 on the current collector portion 28a when the positive electrode current collecting tab 12 is sandwiched between the slits 28b. It has been.

  Moreover, the welding part 29c is used as a to-be-welded metal for welding the negative electrode current collection tab 13 pinched by the slit 29b and the current collection part 29a. The welded portion 29c is formed integrally with the current collecting portion 29a, for example. The welded portion 29c is provided so as to protrude in the winding axis direction of the electrode group 11 from the surface located on the opposite side of the electrode group 11 on the current collector portion 29a when the negative electrode current collecting tab 13 is sandwiched between the slits 29b. It has been.

  FIG. 4 shows an example of a cross-sectional view of a part of the electrode assembly 10 and the cap assembly 20 cut along the line AA shown in FIG.

  The welded portion 28c is provided so as to protrude from the current collecting portion 28a by a height y. The welded portion 28c is formed with a width x on each side of the slit 28b along the slit 28b.

  Moreover, although not shown in figure, the welding part 29c is provided so that only the height y may protrude from the current collection part 29a similarly to the welding part 28c. Further, the welded portion 29c is formed with a width x on each side of the slit 29b along the slit 29b.

  As shown in the drawing, the positive electrode current collecting tab 12 of the electrode group 11 is sandwiched between the slits 28b and fixed by TIG welding. The negative electrode current collecting tab 13 of the electrode group 11 is sandwiched between the slits 29b and fixed by TIG welding.

  When TIG welding is performed, pressure is applied from both outer sides of the current collector 28a (in the direction of arrow B in FIG. 4) by a pressurizing mechanism 40 such as a clamp. As a result, the bifurcated current collecting portion 28 a of the positive electrode lead 28 is deformed, and the slit 28 b is filled with the positive electrode current collecting tab 12. Further, pressure is also applied to the negative electrode lead 29 side from both outer sides of the current collector 29 a by the pressurizing mechanism 40. As a result, the bifurcated current collecting portion 29 a of the negative electrode lead 29 is deformed, and the slit 29 b is filled with the negative electrode current collecting tab 13. As a result, the positive electrode current collecting tab 12 and the negative electrode current collecting tab are in contact with the welded portions 28c and 29c, respectively.

  In this state, arc discharge is performed from the tungsten electrode to the end portion of the positive electrode current collecting tab 12 and the welded portion 28c, whereby the positive electrode current collecting tab 12 and the welded portion 28c are melted and welded. Further, arc discharge is performed from the tungsten electrode to the end of the negative electrode current collecting tab 13 and the welded portion 29c, whereby the negative electrode current collecting tab 13 and the welded portion 29c are melted and welded.

  In TIG welding, for example, argon gas or helium gas is used as a shielding gas, and an arc discharge is performed from the tungsten electrode to the workpiece while being jetted between the tungsten electrode and the workpiece. This is a welding method for melting an object to be welded. In TIG welding, the tungsten electrode is held at a certain distance from the workpiece. In this state, a voltage is applied to the tungsten electrode and a potential difference is generated between the tungsten electrode and the work piece, thereby generating a discharge in the gas field between the tungsten electrode and the work piece. The work to be welded is melted by the heat generated by the discharge.

  The slit 28b and the welded portion 28c are formed along the direction in which the positive electrode current collecting tabs 12 are bundled, that is, the longitudinal direction of the positive electrode lead 28. For this reason, the tungsten electrode is shifted along the longitudinal direction of the positive electrode lead 28 while the discharge is continued. Thereby, the edge part of the positive electrode current collection tab 12 pinched | interposed by the slit 28b formed along the longitudinal direction of the positive electrode lead 28, and the welding part 28c are welded. As a result, as shown in FIG. 5, the positive electrode current collector tab 12 and the welded portion 28c are melted and solidified to form a weld bead 28d.

  The slit 29 b and the welded portion 29 c are formed along the direction in which the negative electrode current collecting tabs 13 are bundled, that is, the longitudinal direction of the negative electrode lead 29. For this reason, the tungsten electrode is shifted along the longitudinal direction of the negative electrode lead 29 in a state where discharge is continued. As a result, the end of the negative electrode current collecting tab 13 sandwiched between the slits 29b formed along the longitudinal direction of the negative electrode lead 29 and the welded portion 29c are welded. As a result, also on the negative electrode lead 29 side, the negative electrode current collecting tab 13 and the welded portion 29c are melted and solidified to form a weld bead 29d.

  The tungsten electrode is driven by, for example, an alternating current having a base current of 60 A, a maximum current of 80 A, and a frequency of 10 Hz. Furthermore, the tungsten electrode is shifted at a speed of 0.25 m / min from one end of the slit 28b to the other end of the slit 28b, for example.

  Further, it is assumed that TIG welding is performed under the above conditions, and that the height y of the welded portions 28c and 29c is provided so as to protrude by “1.0 mm”. For example, when the width x of the welded portions 28c and 29c is “0.5 mm”, the weld beads 28d and 29d are formed. Further, when the width x of the welded portions 28c and 29c is “1.0 mm”, the weld beads 28d and 29d are formed. Furthermore, for example, when the width x of the welded portions 28c and 29c is “0.3 mm”, the molten positive electrode current collecting tab 12 and welded portion 28c, negative electrode current collecting tab 13 and welded portion 29c are scattered, and the weld bead. 28d and 29d are not formed.

  It is desirable that the end of the positive electrode current collecting tab 12 sandwiched between the slits 28b is disposed so as to be positioned at a height higher than the current collecting portion 28a. That is, it is desirable that the end portion of the positive electrode current collecting tab 12 is sandwiched so as to protrude between the welded portions 28c or from the welded portion 28c. Moreover, it is desirable that the end portion of the negative electrode current collecting tab 13 sandwiched between the slits 29b is disposed so as to be positioned at a height higher than the current collecting portion 29a. That is, it is desirable that the end portion of the negative electrode current collecting tab 13 is sandwiched so as to protrude between the welded portions 29c or from the welded portion 29c.

  According to the above-described configuration, the positive electrode lead 28 and the negative electrode lead 29 are formed of the filler material (welded portions 28c and 29c) necessary for TIG welding the positive electrode current collecting tab 12 and the negative electrode current collecting tab 13, and the positive electrode current collector. A conductive path (current collectors 28a and 29a) connecting the positive electrode current collector tab 12 and the negative electrode current collector tab 13 to the positive electrode terminal 14 and the negative electrode terminal 15 when welded to the current tab 12 and the negative electrode current collector tab 13; Is provided. The welded portions 28c and 29c are provided so as to protrude in the winding axis direction of the electrode group 11 from the current collecting portions 28a and 29a. Thereby, the positive electrode current collection tab 12 is inserted | pinched by the welding part 28c and the current collection part 28a at the time of welding, and the negative electrode current collection tab 13 is inserted | pinched by the welding part 29c and the current collection part 29a.

  In such a configuration, when arc discharge is performed from the tungsten electrode to the end portion of the positive electrode current collecting tab 12 and the welded portion 28c and the end portion of the negative electrode current collecting tab 13 and the welded portion 29c, the positive electrode current collecting tab is The welded portion 28c and the welded portion 29c are melted and welded together with the anode 12 and the negative electrode current collecting tab 13. That is, the positive electrode lead 28 and the negative electrode lead 29 can prevent scattering when the positive electrode current collecting tab 12 and the negative electrode current collecting tab 13 are melted. As a result, it is possible to provide a secondary battery that can be manufactured more easily and a method for manufacturing the secondary battery.

  FIG. 6 shows another example of a cross-sectional view of a part of the electrode assembly 10 and the cap assembly 20 cut along the line AA shown in FIG.

  This example is different from the example of FIG. 4 in that the positive electrode current collecting tab 12 and the negative electrode current collecting tab 13 are respectively bundled by the backup lead 16.

  In order to facilitate assembly, the positive electrode current collecting tab 12 and the negative electrode current collecting tab 13 are generally bundled by the backup leads 16 in a predetermined number of ranges. The backup lead 16 is a conductive member formed of a pure aluminum-based aluminum alloy (for example, A1050). In this way, the positive electrode current collecting tab 12 and the negative electrode current collecting tab 13 are bundled by the backup lead 16, so that the positive electrode current collecting tab 12 and the negative electrode current collecting tab 13 can be easily inserted into the slits 28b and 29b, respectively.

  In this case, for example, pressure is applied from both outer sides of the current collector 28a (in the direction of arrow B in FIG. 6) by a pressurizing mechanism 40 such as a clamp. As a result, the bifurcated current collecting portion 28 a of the positive electrode lead 28 is deformed, and the slit 28 b is filled with the positive electrode current collecting tab 12 and the backup lead 16 bundled with the positive electrode current collecting tab 12. Further, pressure is also applied to the negative electrode lead 29 side from both outer sides of the current collector 29 a by the pressurizing mechanism 40. As a result, the bifurcated current collecting portion 29 a of the negative electrode lead 29 is deformed, and the slit 29 b is filled with the negative electrode current collecting tab 13 and the backup lead 16 in which the negative electrode current collecting tab 13 is bundled.

  In this case as well, it is desirable that the end portion of the backup lead 16 in which the positive electrode current collecting tabs 12 sandwiched between the slits 28b are located at a height higher than the current collecting portion 28a. That is, it is desirable that the end portion of the backup lead 16 bundled with the positive electrode current collecting tab 12 is sandwiched between the welded portions 28c or protruding from the welded portion 28c.

  Further, it is desirable that the end portion of the backup lead 16 in which the negative electrode current collecting tabs 13 sandwiched between the slits 29b are bundled so as to be positioned at a height higher than the current collecting portion 29a. That is, it is desirable that the end portion of the backup lead 16 bundled with the negative electrode current collecting tab 13 is sandwiched so as to protrude between the welded portions 29c or from the welded portion 29c.

  With such a configuration, when arc discharge is performed from the tungsten electrode to the end of the backup lead 16 bundled with the positive electrode current collecting tab 12 and the welded portion 28c, the welded portion together with the positive electrode current collecting tab 12 and the backup lead 16 is welded. 28c is melted and the positive electrode current collecting tab 12 and the positive electrode lead 28 are welded. Further, when arc discharge is performed from the tungsten electrode to the end of the backup lead 16 and the welded portion 29 c bundled with the negative electrode current collecting tab 13, the welded portion 29 c is melted together with the negative electrode current collecting tab 13 and the backup lead 16. Thus, the negative electrode current collecting tab 13 and the negative electrode lead 29 are welded.

  Even in such a configuration, the positive electrode lead 28 and the negative electrode lead 29 can be prevented from scattering when the positive electrode current collecting tab 12 and the negative electrode current collecting tab 13 are melted. As a result, it is possible to provide a secondary battery that can be manufactured more easily and a method for manufacturing the secondary battery.

  Further, the positive electrode current collecting tab 12 and the negative electrode current collecting tab 13 may be bundled into a plurality of bundles by the backup lead 16.

  FIG. 7 shows an example of the positive electrode lead 28 when the positive electrode current collecting tab 12 is bundled into three bundles by the backup lead 16. Although the negative electrode lead 29 side is not shown, the illustration is omitted because it has the same configuration as the positive electrode lead 28 side.

  FIG. 8 shows an example of a partial cross-sectional view of the electrode assembly 10 and the cap assembly 20 cut along the CC line shown in FIG.

  7 and 8, the plurality of bundles of the positive electrode current collecting tabs 12 bundled by the backup lead 16 and the plurality of connection plates 30 are inserted into the slits 28b of the positive electrode lead 28, and the gap is filled. It becomes a state. On the negative electrode lead 29 side, a plurality of bundles of the negative electrode current collecting tabs 13 bundled in the slit 29b by the backup lead 16 and a plurality of connection plates 31 are inserted to fill the gap.

  Also in this example, the positive electrode lead 28 includes a welded portion 28c formed with a width x on each side of the slit 28b along the slit 28b. Further, the welded portion 28c is provided so as to protrude from the current collecting portion 28a by a height y. Further, the negative electrode lead 29 includes a welded portion 29c formed with a width x on each side of the slit 29b along the slit 29b. Further, the welded portion 29c is provided so as to protrude from the current collecting portion 29a by a height y.

  Each connection plate 30 is a conductive member that is sandwiched between the slits 28 b of the positive electrode lead 28. The connection plate 30 is made of the same material as the positive electrode lead 28. When the connecting plate 30 is welded together with the positive electrode lead 28 and the positive electrode current collecting tab 12, the connecting plate 30 functions as a conductive member for electrically connecting the positive electrode current collecting tab 12 and the positive electrode lead 28.

  Each connection plate 31 is a conductive member that is sandwiched between the slits 29 b of the negative electrode lead 29. The connection plate 31 is made of the same material as the negative electrode lead 29. When the connecting plate 31 is welded together with the negative electrode lead 29 and the negative electrode current collecting tab 13, the connecting plate 31 functions as a conductive member for electrically connecting the negative electrode current collecting tab 13 and the negative electrode lead 29.

  The connection plate 30 includes a base member 30a formed as a rectangular parallelepiped and projecting portions 30b provided along two long sides of one surface of the base member 30a. The protrusions 30b are formed so as to protrude from the base member 30a by y. Furthermore, each protrusion 30b is formed with a width x.

  Moreover, the connection board 31 has the base member 31a formed in the rectangular parallelepiped, and the protrusion part 31b provided along two long sides of one surface of the base member 31a. The protruding portions 31b are formed so as to protrude by y with respect to the base member 31a. Furthermore, each protrusion 31b is formed with a width x.

  The shape of the base members 30a and 31a may be any shape as long as the shape has a side parallel to the side where the weld 28c or 29c of the positive electrode lead 28 or the negative electrode lead 29 is provided. In this case, the protrusions 30b and 31b are provided on a side parallel to the side where the welded portion 28c or 29c of the positive electrode lead 28 or the negative electrode lead 29 is provided.

  In this case, for example, pressure is applied from both outer sides (in the direction of arrow B in FIG. 8) of the current collector 28a by a pressurizing mechanism 40 such as a clamp. As a result, the space between the bifurcated current collecting portions 28 a of the positive electrode lead 28 is filled with the positive electrode current collecting tab 12, the backup lead 16 bundled with the positive electrode current collecting tab 12, and the connection plate 30. Further, pressure is also applied to the negative electrode lead 29 side from both outer sides of the current collector 29 a by the pressurizing mechanism 40. As a result, the space between the bifurcated current collecting portions 29 a of the negative electrode lead 29 is filled with the negative electrode current collecting tab 13, the backup lead 16 in which the negative electrode current collecting tab 13 is bundled, and the connection plate 31.

  As shown in FIG. 8, two of the plurality of backup leads 16 bundled with the positive electrode current collecting tab 12 are sandwiched between the positive electrode lead 28 and the connection plate 30. In this case, it is desirable that the end portion of the backup lead 16 in which the positive electrode current collecting tab 12 is bundled be disposed at a height higher than the current collecting portion 28a and the base member 30a. That is, it is desirable that the end portion of the backup lead 16 bundled with the positive electrode current collecting tab 12 is sandwiched so as to protrude between the welded portion 28c and the protruding portion 30b or from the welded portion 28c and the protruding portion 30b.

  The remaining one of the plurality of backup leads 16 in which the positive electrode current collecting tabs 12 are bundled is sandwiched between the two connection plates 30. In this case, it is desirable that the end portion of the backup lead 16 in which the positive electrode current collecting tabs 12 are bundled be positioned so as to be at a height higher than the base member 30a. That is, it is desirable that the end portion of the backup lead 16 bundled with the positive electrode current collecting tab 12 is sandwiched so as to protrude between the two protruding portions 30b or from the two protruding portions 30b.

  Two of the plurality of backup leads 16 in which the negative electrode current collecting tabs 13 are bundled are sandwiched between the negative electrode lead 29 and the connection plate 31. In this case, it is desirable that the end portion of the backup lead 16 bundled with the negative electrode current collecting tab 13 is disposed at a height higher than the current collecting portion 29a and the base member 31a. That is, it is desirable that the end portion of the backup lead 16 bundled with the negative electrode current collecting tab 13 is sandwiched so as to protrude between the welded portion 29c and the protruding portion 31b or from the welded portion 29c and the protruding portion 31b.

  Further, the remaining one of the plurality of backup leads 16 in which the negative electrode current collecting tabs 13 are bundled is sandwiched between the two connection plates 31. In this case, it is desirable that the end portion of the backup lead 16 bundled with the negative electrode current collecting tab 13 is disposed so as to be positioned at a height higher than the base member 31a. That is, it is desirable that the end portion of the backup lead 16 bundled with the negative electrode current collecting tab 13 is sandwiched so as to protrude between the two protruding portions 31b or from the two protruding portions 31b.

  With such a configuration, when arc discharge is performed from the tungsten electrode to the ends of the plurality of backup leads 16, the welded portions 28 c, and the protruding portions 30 b, each of which has the positive electrode current collecting tabs 12 bundled, The welded portion 28 c and the protruding portion 30 b are melted together with the electric tab 12 and the backup lead 16, and the positive electrode current collecting tab 12, the positive electrode lead 28, and the connection plate 30 are welded.

  Further, when arc discharge is performed from the tungsten electrode to the ends of the plurality of backup leads 16 in which the negative electrode current collecting tabs 13 are bundled, the welded portions 29c, and the protruding portions 31b, the negative electrode current collecting tabs 13 and The welded portion 29c and the protruding portion 31b are melted together with the backup lead 16, and the negative electrode current collecting tab 13, the negative electrode lead 29, and the connection plate 31 are welded.

  Even in such a configuration, the positive electrode lead 28 and the negative electrode lead 29 can be prevented from scattering when the positive electrode current collecting tab 12 and the negative electrode current collecting tab 13 are melted. As a result, it is possible to provide a secondary battery that can be manufactured more easily and a method for manufacturing the secondary battery.

  The positive electrode current collecting tab 12 and the negative electrode current collecting tab 13 may be configured to be bundled in any number of bundles by the backup lead 16.

  In the above embodiment, the positive electrode lead 28 and the negative electrode lead 29 are formed in the slits 28b and 29b formed between the bifurcated current collectors 28a and 29a, respectively, and the positive electrode current collecting tab 12, the connection plate 30, and the negative electrode Although it has been described that the current collecting tab 13 and the connection plate 31 are sandwiched, the present invention is not limited to this configuration. The positive electrode lead 28 and the negative electrode lead 29 may have any shape.

  For example, each of the positive electrode lead and the negative electrode lead has a current collecting portion formed in a rectangular parallelepiped and a weld portion provided along two long sides of one surface of the current collecting portion. The welds are formed so as to protrude by y with respect to the current collector. Furthermore, the welds are each formed with a width x.

  When the welded portion is welded to the positive electrode current collector tab 12 or the negative electrode current collector tab 13, the weld portion protrudes in the winding axis direction of the electrode group 11 from the surface located on the opposite side of the electrode group 11 on the current collector portion. Is provided.

  The positive electrode current collecting tab 12 is bundled by a backup lead 16 in two or more bundles. The positive electrode current collecting tabs 12 bundled by the backup lead 16 are sandwiched between the positive electrode lead 28 and the connection plate by the pressurizing mechanism 40 such as a clamp together with the backup lead 16. In this case, the positive electrode lead is sandwiched between the two connection plates. Further, the positive electrode current collecting tab 12 bundled by the backup lead 16 is sandwiched between the connection plate and the positive electrode lead.

  Further, the negative electrode current collecting tab 13 is bundled by a backup lead 16 in two or more bundles. The negative electrode current collecting tabs 13 bundled by the backup lead 16 are sandwiched between the negative electrode lead 29 and the connecting plate by the pressurizing mechanism 40 such as a clamp together with the backup lead 16. In this case, the negative electrode lead is sandwiched between the two connection plates. Further, the negative electrode current collecting tab 13 bundled by the backup lead 16 is sandwiched between the connection plate and the negative electrode lead.

  Also in this example, each connection plate is formed of the same material as the positive electrode lead or the negative electrode lead. The connection plate includes a base member formed in a rectangular parallelepiped and a protrusion provided along one long side of one surface of the base member. The protrusion is formed to protrude by y with respect to the base member. Furthermore, the protrusion is formed with a width x.

  When the positive electrode current collecting tabs 12 are bundled, the ends of the plurality of backup leads 16 are sandwiched between the positive electrode lead and the connection plate and the protruding portion of the connection plate. Note that the ends of the plurality of backup leads 16 in which the positive electrode current collecting tabs 12 are bundled may be sandwiched so as to protrude from the welded portion of the positive electrode lead and the protruding portion of the connection plate.

  When the negative electrode current collecting tabs 13 are bundled together, the ends of the plurality of backup leads 16 are sandwiched between the negative electrode lead and the connecting plate, and are sandwiched between the negative electrode lead welded portion and the protruding portion of the connecting plate. Note that the ends of the plurality of backup leads 16 in which the negative electrode current collecting tabs 13 are bundled may be sandwiched so as to protrude from the welded portion of the negative electrode lead and the protruding portion of the connection plate.

  With such a configuration, arc discharge was performed from the tungsten electrode to the ends of the plurality of backup leads 16 bundled with the positive electrode current collecting tab 12, the welded portion of the positive electrode lead, and the protruding portion of the connection plate. In this case, the welded portion and the protruding portion are melted together with the positive electrode current collecting tab 12 and the backup lead 16, and the positive electrode current collecting tab 12, the positive electrode lead, and the connection plate are welded.

  Further, when arc discharge is performed from the tungsten electrode to the ends of the plurality of backup leads 16 bundled with the negative electrode current collecting tabs 13, the welded portions of the negative electrode leads, and the protruding portions of the connection plate, The welded portion and the protruding portion are melted together with the electric tab 13 and the backup lead 16, and the negative electrode current collecting tab 13, the negative electrode lead, and the connection plate are welded.

  Even in such a configuration, the positive electrode lead and the negative electrode lead can be prevented from being scattered when the positive electrode current collecting tab 12 and the negative electrode current collecting tab 13 are melted. As a result, it is possible to provide a secondary battery that can be manufactured more easily and a method for manufacturing the secondary battery.

  When welding is performed by TIG welding, the melted current collecting tab is likely to be scattered as compared with other welding methods. However, according to the lead having the above-described shape, the current collecting tab and a part of the lead are melted at the same timing, so that the mass of the molten metal melted can be increased. As a result, even when TIG welding is performed, scattering of the melted current collecting tab can be prevented.

  In the above embodiment, the example in which the current collecting tab and the lead are welded by TIG welding has been described, but the present invention is not limited to this configuration. Even when other welding methods are used, scattering of the melted current collecting tab can be suppressed. However, when welding is performed by TIG welding, this effect is more prominent, so TIG welding is taken as an example. Explained.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Secondary battery, 2 ... Cap assembly, 10 ... Electrode assembly, 11 ... Electrode group, 12 ... Positive electrode current collection tab, 13 ... Negative electrode current collection tab, 14 ... Positive electrode terminal, 15 ... Negative electrode terminal, 16 ... Backup Lead, 19 ... outer can, 20 ... cap assembly, 21 ... electrode-cap assembly, 23 ... gasket, 24 ... cap, 28 ... positive electrode lead, 28a ... current collector, 28b ... slit, 28c ... weld, 28d ... weld bead, 29 ... negative electrode lead, 29a ... current collecting part, 29b ... slit, 29c ... welded part, 29d ... weld bead, 30 ... connection plate, 30a ... base member, 30b ... projecting part, 31 ... connection plate, 31a ... base member, 31b ... protrusion, 32 ... electrode guard, 40 ... pressurizing mechanism.

Claims (7)

A group of electrodes in which a positive electrode and a negative electrode stacked through a separator are wound into a flat shape;
A terminal,
A lead having a current collector connected to the terminal and a weld provided to protrude from the current collector;
A current collecting tab welded to the lead by extending from the electrode group and being melted together with the welded portion in contact with the current collecting portion and the welded portion;
A secondary battery comprising:   2. The secondary battery according to claim 1, wherein the welded portion is provided so as to protrude in a winding axis direction of the electrode group from a surface located on a side opposite to the electrode group on the current collector. The current collector is formed in a bifurcated shape,
The weld is provided along a slit between the two-pronged shapes of the current collector,
The secondary battery according to claim 2.   The secondary battery according to claim 3, wherein the current collecting tab is pressed by a pressure mechanism while being inserted into the slit and is brought into contact with the current collecting portion and the welding portion. A base member having sides parallel to the current collector, and parallel to the current collector so as to protrude in a winding axis direction of the electrode group from a surface on the base member opposite to the electrode group. And a protrusion provided on the side, further comprising a connection plate sandwiched between the forked shape of the current collector,
In a state where the current collecting tab is sandwiched between the base member and the current collecting part and is pressed by a pressurizing mechanism and is in contact with the current collecting part, the welded part, the base member and the protruding part. The secondary battery according to claim 3, wherein the secondary battery is welded to the lead and the connection plate by being melted together with the welded portion and the protruding portion. A base member having a side parallel to the side of the current collector, and the current collector so as to project in a winding axis direction of the electrode group from a surface on the base member opposite to the electrode group; A connecting plate provided to be pressed by the pressurizing mechanism against the current collector through the current collecting tab, and a protrusion provided on a parallel side,
The weld is provided along the side of the current collector,
In a state where the current collecting tab is sandwiched between the base member and the current collecting part and is pressed by a pressurizing mechanism and is in contact with the current collecting part, the welded part, the base member and the protruding part. The secondary battery according to claim 2, wherein the secondary battery is welded to the lead and the connection plate by being melted together with the welded portion and the protruding portion. An electrode group in which a positive electrode and a negative electrode, which are stacked via a separator, are wound into a flat shape, a terminal, a lead having a current collector connected to the terminal, and a current collecting tab extending from the electrode group; A method for producing a secondary battery comprising:
Forming a weld so as to protrude from the current collector,
A pressure mechanism to bring the current collecting tab into contact with the current collecting portion and the welded portion;
Melting the current collecting tab abutted against the weld and the weld and welding the lead and the current collecting tab;
A method for manufacturing a secondary battery.