JP5566651B2 - Battery and manufacturing method thereof - Google Patents

Description

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

  In recent years, with the development of electronic devices, lithium secondary batteries have been developed as non-aqueous electrolyte secondary batteries that are small, lightweight, have high energy density, and can be repeatedly charged and discharged. Recently, it is suitable for in-vehicle secondary batteries mounted on hybrid cars and electric cars, and secondary batteries for power storage used for power leveling. Development of non-aqueous electrolyte secondary batteries is also desired. As such a secondary battery, rapid charging and high power discharge are possible using lithium titanium oxide (lithium titanium composite oxide) having a small particle size (average particle size of primary particles is 1 μm or less) as a negative electrode active material. In addition, non-aqueous electrolyte secondary batteries having excellent cycle performance have been developed.

  Due to the demand for a secondary battery with high energy density, it is necessary to combine a plurality of current collecting tabs. For example, Patent Document 1 describes that damage to the current collecting tabs is reduced by using protective leads. Has been. In this case, the defective rate at the time of ultrasonic bonding is reduced by ultrasonically bonding a plurality of stacked current collecting tabs to the leads while being sandwiched between the protective leads.

JP 2009-87728 A

  When a plurality of current collecting tabs are stacked, misalignment may occur at the width end. When such a plurality of current collecting tabs and leads are ultrasonically bonded, sufficient strength cannot always be obtained. During and after the assembly of the electrode group into the container, the current collecting tab is easily cut by an external force. In addition, the characteristics during rapid charge and large current discharge are not stable.

  An object of the present invention is to provide a battery having a high strength of a current collecting tab against an external force and having stable characteristics during rapid charge and large current discharge, and a method for manufacturing the same.

The battery of the present invention includes an electrode group including a positive electrode and a negative electrode,
Wherein the group of electrodes positive electrode or the negative electrode and are electrically connected, Ri Do of aluminum or an aluminum alloy, a plurality of current collecting tabs are stacked with a positional deviation in the width end,
Protective leads sandwiching the plurality of current collecting tabs;
A battery comprising a plurality of current collecting tabs sandwiched between the protective leads and ultrasonically bonded to the lead made of aluminum or an aluminum alloy,
The ultrasonic joint is formed without crossing the width ends of any of the current collecting tabs constituting the plurality of current collecting tabs.

  Further, the battery manufacturing method of the present invention is the battery manufacturing method described above, and is sandwiched between the protective leads so as not to cross the width ends of any of the current collecting tabs constituting the plurality of current collecting tabs. Further, the plurality of current collecting tabs and the leads are joined by ultrasonic waves.

  ADVANTAGE OF THE INVENTION According to this invention, the intensity | strength of the current collection tab with respect to external force is high, and the battery which the characteristic at the time of rapid charge and large current discharge was stabilized, and its manufacturing method can be provided.

The disassembled perspective view which shows the nonaqueous electrolyte battery which concerns on one Embodiment. The top view which shows an example of the ultrasonic junction part of the current collection tab in the battery shown in FIG. 1, a protection lead, and a lead. Schematic which shows the process of carrying out ultrasonic bonding of the current collection tab pinched | interposed into the protection lead, and a lead. The schematic diagram explaining the relationship between the width | variety of a current collection tab and the width | variety of an ultrasonic junction part. The schematic diagram explaining the relationship between the width | variety of a current collection tab and the width | variety of an ultrasonic junction part. The schematic diagram explaining the relationship between the width | variety of a current collection tab and the width | variety of an ultrasonic junction part. The disassembled perspective view which shows the nonaqueous electrolyte battery which concerns on other embodiment. The disassembled perspective view which shows the nonaqueous electrolyte battery which concerns on other embodiment. The top view which shows an example of the ultrasonic junction part of the current collection tab in the battery shown in FIG. 8, a protection lead, and a lead. The schematic diagram explaining the relationship between the gap | deviation width | variety of a current collection tab, and the position of an ultrasonic junction part. The schematic diagram explaining the relationship between the gap | deviation width | variety of a current collection tab, and the position of an ultrasonic junction part. The schematic diagram explaining the relationship between the gap | deviation width | variety of a current collection tab, and the position of an ultrasonic junction part. The schematic diagram explaining the relationship between the gap | deviation width | variety of a current collection tab, and the position of an ultrasonic junction part. FIG. 3 is a schematic diagram showing the position of an ultrasonic bonding part in Sample 1. Results of tensile test of sample 1 tab. FIG. 4 is a schematic diagram showing the position of an ultrasonic bonding part in Sample 2. Results of tensile test of sample 2 tab. FIG. 4 is a schematic diagram showing the position of an ultrasonic bonding part in Sample 3. The tensile test result of the tab of Sample 3. FIG. 4 is a schematic diagram showing the position of an ultrasonic bonding part in Sample 4. The tensile test result of the tab of Sample 4. FIG. 6 is a schematic diagram showing the position of an ultrasonic bonding portion in sample 5. Tensile test result of sample 5 tab. FIG. 6 is a schematic diagram showing the position of an ultrasonic bonding portion in sample 6. Results of tensile test of sample 6 tab. FIG. 5 is a schematic diagram showing the position of an ultrasonic bonding portion in sample 7. Tensile test results of sample 7 tab. The graph which shows the relationship between the gap | deviation width of a tab, and tensile strength.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The battery according to one embodiment is a nonaqueous electrolyte battery, and includes a container 31 having a bottomed rectangular tube shape as shown in FIG. The container 31 is formed, for example, by subjecting an aluminum plate or an aluminum alloy plate to deep drawing. The electrode group 32 is formed by, for example, winding a sheet-like positive electrode and a sheet-like negative electrode in a spiral shape with a separator interposed therebetween, and then crushing and deforming the whole into a quadrangular cross-sectional shape that matches the cross-sectional shape of the container. It is produced by this.

  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. As the positive electrode active material, oxides, sulfides, polymers, and the like that can occlude and 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. As the negative electrode active material, metal oxides, metal sulfides, metal nitrides, alloys, and the like that can occlude and release lithium can be used. Preferably, the occlusion and release potential of lithium ions is 0.4 V or higher relative to the metal lithium potential. It is a substance. 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 oxide, tungsten oxide, amorphous tin oxide, tin silicon oxide, and silicon oxide. Among these, 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.

A non-aqueous electrolyte (not shown) is accommodated in the container 31 and impregnated in the electrode group 32. The non-aqueous electrolyte is prepared by dissolving an electrolyte (for example, a lithium salt) in a non-aqueous solvent. 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 (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and trifluoromethanesulfone. Examples thereof include lithium salts such as lithium acid lithium (LiCF ₃ SO ₃ ). 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.

  The plurality of strip-like positive electrode current collecting tabs 34 are electrically connected to a plurality of positions of the positive electrode, and are respectively led upward from the upper end surface 32 a of the electrode group 32. On the other hand, the plurality of strip-shaped negative electrode current collecting tabs 35 are electrically connected to a plurality of portions of the negative electrode, and are respectively led upward from the upper end surface 32 a of the electrode group 32.

  As the positive electrode current collecting tab 34, for example, a positive electrode current collector partially extended can be used, but it may be separate from the positive electrode. Moreover, as the negative electrode current collection tab 35, for example, a negative electrode current collector partially extended can be used, but may be separate from the negative electrode. In the case of a separate body, a current collecting tab made of a conductive material is electrically connected to the current collector by ultrasonic bonding or the like.

  The positive electrode current collecting tab 34 and the negative electrode current collecting tab 35 are sandwiched between a protective lead 36 and a protective lead 37, respectively. Specifically, the current collecting tab is sandwiched between U-shaped bent protective leads in a state where a plurality of current collecting tabs are stacked in the thickness direction. The material of the protective lead can be, for example, aluminum or an aluminum alloy. By ultrasonically bonding the current collecting tab with the protective lead, the risk of cracking in the current collecting tab is reduced. For this reason, the joint strength of the protective lead, the current collecting tab and the lead can be sufficiently increased.

  The thickness of the protective leads 36 and 37 is desirably larger than three times the thickness per current collecting tab. Since it has sufficient thickness, it is avoided that the protective lead cracks. Furthermore, the thickness of the protective lead is preferably thinner than the thickness of the lead. Since a thin protective lead can be disposed on the horn side when ultrasonic bonding is performed, there is no need to increase the pressure applied to the horn and there is no possibility of cracking the current collecting tab.

  The thickness of the protective leads 36 and 37 is preferably within a range of 0.05 to 0.6 mm, and more preferably within a range of 0.1 to 0.5 mm. Further, the width of the protective lead is not particularly defined as long as it is larger than the width of the joint portion 59. The protective lead does not need to be a single folded plate that covers both surfaces of the stacked current collecting tabs. Separate protective leads may be disposed on both sides of the stacked current collecting tabs.

  The opening of the container 31 is sealed with a sealing member. The sealing member includes a lid 38 that closes the opening of the container 31, a negative output terminal (rivet) 40 that is attached to the outer surface (upper surface) of the lid 38 via a gasket 39, and a convex surface on the outer surface (upper surface) side of the lid 38. And a positive electrode output terminal 43 protruding in a shape. Although not shown, the lid 38 is provided with an electrolyte solution inlet and a safety valve. The negative electrode lead 41 is L-shaped having an upper surface and a side surface, and is disposed on the inner surface (lower surface) of the lid 38 via an insulating member (not shown). The upper surface of the negative electrode lead 41 is electrically connected to the negative electrode output terminal 40 by being caulked and fixed to the negative electrode output terminal 40. On the other hand, the positive electrode lead 42 is electrically connected to the positive electrode output terminal 43 by being disposed directly on the inner surface (lower surface) of the lid 38. The electrolyte solution (not shown) is injected from the electrolyte solution injection hole (not shown) and then closed with a sealing plug (not shown). This sealing plug is welded to the lid 38.

  The L-shaped negative electrode lead 41 is connected to the negative electrode current collecting tab 35. Specifically, as shown in FIG. 2, the side surface of the negative electrode lead 41 is joined to the negative electrode current collecting tab 35 sandwiched between the protective leads 37 by ultrasonic waves. The ultrasonic joint is shown as reference numeral 59. The negative electrode current collecting tab 35 and the negative electrode lead 41 sandwiched between the protective leads 37 can be joined by ultrasonic waves using, for example, an anvil 21 and a horn 22 as shown in FIG. As a result, the negative electrode current collecting tab 35 is electrically connected to the negative electrode output terminal 40 via the negative electrode protective lead 37 and the negative electrode lead 41. It should be noted that the anvil and the horn may be appropriately selected according to the desired size and position of the joining portion 59 by ultrasonic waves.

  It is preferable that the width of the ultrasonic bonded portion 59 is defined so as to have a specific relationship with the width of the current collecting tab. In FIG. 4, the relationship between the width | variety of a current collection tab and the width | variety of a junction part is shown. For the sake of explanation, the stacked current collecting tabs in the figure are also shown with a deviation in the depth direction of the drawing (tab length direction). Assume that the width of each current collecting tab 35 is A, the width of the stacked current collecting tabs is E, and the width of the ultrasonic bonding portion 59 in the width direction of the current collecting tabs is C. As shown in FIG. 4, in the case of C = 2A-E, the width of the portion where all of the plurality of tabs are stacked is 2A-E, so the end of the joint portion 59 is the width end of the current collecting tab 35. Matches.

  In the case of C <2A-E, the joint portion 59 does not reach the width end of the current collecting tab 35 as shown in FIG. The joint portion 59 is formed in a region where all the stacked current collecting tabs overlap each other, and does not cross the width end of any current collecting tab. That is, if C ≦ 2A-E, the joint portion 59 can be formed so as not to step on the width end of the current collecting tab.

  On the other hand, in the case of C> 2A-E, as shown in FIG. 6, the joint portion 59 always steps on the width end of one of the current collecting tabs and extends to the outside. Since the width to be joined by the ultrasonic wave is narrow, the joining becomes insufficient, and if even one current collecting tab exists, the strength is lowered.

  Based on these, in the present invention, the ultrasonic bonding portion 59 is defined so as not to cross any width end of the plurality of current collecting tabs. As described above, a tab whose width end is stepped on the joint portion 59 has a narrow width to be joined, and the strength is lowered if even one such tab exists. The width C of the joint portion 59 is preferably defined within the following range.

C ≦ 2A-E (1)
In the present invention, the ultrasonic bonded portion 59 is formed in a region where all the current collecting tabs overlap without crossing the width ends of the current collecting tabs. As a result, all current collecting tabs are ultrasonically bonded with an equal width. There are no current collecting tabs with a smaller joint width compared to other current collecting tabs, that is, current collecting tabs with incomplete joining. Since the strength of the stacked current collecting tabs is increased, the possibility of inconvenience such as cutting of the current collecting tabs is reduced. Stable battery characteristics can be obtained by increasing the strength against external force during and after assembly of the electrode group into the container.

  The positive electrode current collecting tab 34 and the positive electrode lead 42 are preferably joined in the same manner as the negative electrode side. That is, the positive electrode current collecting tab 34 sandwiched between the protective leads 36 is bonded to the positive electrode lead 42 by ultrasonic waves, and all the tabs are overlapped so that the ultrasonic bonded portion does not cross the width end of the current collecting tabs. Formed in the region. Moreover, it is preferable that the width of the joint is defined so as to have a specific relationship (1) with the width of the current collecting tab.

  In this case, since the strength of the current collecting tab is increased on both the positive electrode side and the negative electrode side, the strength against an external force during and after the battery is incorporated becomes even higher.

  As shown in FIG. 1, so as to surround a space provided between the inner surface (lower surface) of the lid 38 and the upper end surface 32a from which the positive electrode current collecting tab 34 and the negative electrode current collecting tab 35 of the electrode group 32 protrude. Spacers 51a and 51b are arranged. The spacer 51a is provided with partition plates 52a to 52c at both short sides of the rectangular plate and an intermediate point in the long side direction. Projections 53 are provided on the end surfaces of the partition plates 52a to 52c.

  On the other hand, the spacer 51b is provided with partition plates 54a to 54c at both short sides of the rectangular plate and an intermediate point in the long side direction. Concave portions 55 for fitting the protrusions 53 of the spacers 51a are provided on the end surfaces of the partition plates 54a to 54c. When the projections 53 of the partition plates 52a to 52c of the spacer 51a are fitted into the recesses 55 of the partition plates 54a to 54c of the spacer 51b, they are surrounded by the partition plates 52a and 52b of the spacer 51a and the partition plates 54a and 54b of the spacer 51b. The positive electrode current collecting tab 34, the positive electrode protection lead 36, and the positive electrode lead 42 are positioned in the space, and the negative electrode current collector is in a space surrounded by the partition plates 52b and 52c of the spacer 51a and the partition plates 54b and 54c of the spacer 51b. The electric tab 35, the negative electrode protection lead 37, and the negative electrode lead 41 are located. Thereby, the insulation between the positive electrode current collecting tab 34 and the negative electrode current collecting tab 35, the insulation between the positive electrode protection lead 36 and the negative electrode protection lead 37, the insulation between the positive electrode lead 42 and the negative electrode lead 41, the insulation between these members and the container 31. Is achieved.

  The spacers 51a and 51b can prevent the electrode group 32 from moving when vibration or impact is applied to the battery. Furthermore, since the electrolyte injected from the electrolyte injection hole accumulates in the upper part of the electrode group 32, the electrolyte easily penetrates from the upper end surface of the electrode group 32, and the electrode group 32 can be uniformly impregnated with the electrolyte. it can. Holes 56 are provided in the four corners of the spacers 51a and 51b to allow the electrolyte to penetrate into the gap between the container 31 and the electrode group 32. Examples of the material of the spacers 51a and 51b include PP and PFA.

  In the present embodiment, since the plurality of current collecting tabs joined to the leads have sufficiently large strength, inconvenience such as tab cutting is reduced, and an increase in resistance can be suppressed. Therefore, a battery excellent in quick charge characteristics and large current output characteristics can be obtained.

  The nonaqueous electrolyte battery having the above-described configuration can also be applied to a laminated piece-out configuration as shown in FIG. The nonaqueous electrolyte battery shown in the figure has an electrode group 33 produced by alternately laminating a sheet-like positive electrode and a sheet-like negative electrode with a separator interposed therebetween.

  Except for these differences, the illustrated battery has the same configuration as the nonaqueous electrolyte battery shown in FIG. 1, and the current collecting tab, the protective lead, and the lead are joined by ultrasonic waves in the same manner as described above. The ultrasonic bonding portion is formed only in a region where all the current collecting tabs overlap so as not to cross the width end of the current collecting tabs. Since the current collecting tab has a sufficiently large strength, inconvenience such as cutting of the current collecting tab is reduced. Moreover, the width C of the ultrasonic bonding portion has a specific relationship with the width of the current collecting tab (C ≦ 2A-E, A is the width of each current collecting tab, and E is a stacked current collecting tab. Is preferably defined as having an overall width. As a result, a battery having excellent quick charge characteristics and large current output characteristics can be obtained.

  FIG. 8 is an example of a wound-double-type non-aqueous electrolyte battery, and an electrode group 2 is accommodated in a container 1. The electrode group 2 is produced by alternately stacking a sheet-like positive electrode and a sheet-like negative electrode with a separator in between. The plurality of positive electrode current collecting tabs 3 are electrically connected to a plurality of locations of the positive electrode, and each is led out laterally from one side surface of the stacked electrode surface. The plurality of negative electrode current collecting tabs 4 are electrically connected to a plurality of portions of the negative electrode, and each is led out laterally from the other side surface of the stacked electrode.

  As the positive electrode current collecting tab 3, for example, a positive electrode current collector partially extended can be used, but may be separate from the positive electrode. Further, as the negative electrode current collecting tab 4, for example, a negative electrode current collector partially extended can be used, but may be separate from the negative electrode.

  The opening of the container 1 is sealed with a sealing member. As shown in FIG. 8, the sealing member includes a lid 9 that closes the opening of the container 1, and a positive output terminal 12 and a negative output terminal that are caulked and fixed to the outer surface (upper surface) of the lid 9 via gaskets 10 and 11, respectively. 13 is provided. The lid 9 is made of a press-formed product made of a metal such as aluminum or an aluminum alloy plate. Although not shown, the lid 9 is provided with an electrolyte injection hole and a safety valve. After the electrolyte injection, the electrolyte injection hole is closed with a sealing plug (not shown), and this sealing plug is welded to the lid 9.

On the inner surface (lower surface) of the lid 9, the negative electrode lead 8 is disposed via the insulator 15, and the positive electrode lead 7 is disposed via the insulator 14. Anode lead 8 includes a connecting plate _81, and the connecting plate 8 through hole ₈₂ which is open to _1, and a collector portion 8 ₃ extending downward from the connecting plate _81. Insulator 15 is made of a rectangular plate having a through-hole 15 ₁ is opened. The negative electrode output terminal 13 is a rivet, and has a head portion disposed on the lid 9 and a shaft portion (not shown) extending downward from the head portion. Shaft portion of the negative output terminal 13 is inserted into the through hole ₈₂ of the through-hole 15 ₁ and the negative electrode lead 8 of the insulator 15 is caulked and fixed, that is, the negative output terminal 13 is caulked to the cover 9, further It is also caulked and fixed to the negative electrode lead 8. Thus, the negative electrode lead 8 is electrically connected to the negative electrode output terminal 13.

The positive electrode lead 7 has a connecting plate _71, the through hole 7 ₂ opened in connecting plate _71, and a collector portion 7 ₃ extending downward from the connecting plate _71. Insulator 14 is made of a rectangular plate having a through-hole 14 ₁ is opened. The positive electrode output terminal 12 is a rivet and has a head portion disposed on the lid 9 and a shaft portion (not shown) extending downward from the head portion. The shaft portion of the positive electrode output terminal 12 is inserted into the through hole 14 ₁ of the insulator 14 and the through hole 7 ₂ of the positive electrode lead 7 and fixed by caulking. That is, the positive output terminal 12 is caulked and fixed to the lid 9 and further caulked and fixed to the positive electrode lead 7. Thus, the positive electrode lead 7 is electrically connected to the positive electrode output terminal 12.

  The material of the negative electrode output terminal 13 and the negative electrode lead 8 can be changed according to the material of the active material. For example, when lithium titanate is used as the negative electrode active material, aluminum or an aluminum alloy can be used. On the other hand, for example, aluminum or an aluminum alloy can be used for the positive electrode output terminal 12 and the positive electrode lead 7.

The negative electrode lead 8 is connected to the negative electrode current collecting tab 4. Specifically, the collector portions 8 ₃ of the negative electrode lead 8, 9 are joined by ultrasonic and the negative electrode current collector tab 4 sandwiched protective lead 6 of the negative electrode. The ultrasonic joint is shown as reference numeral 20. The ultrasonic bonding portion is formed only in a region where all the current collecting tabs overlap so as not to cross the width end of the current collecting tabs. Moreover, in the width direction of the current collecting tab 4, the width C of the ultrasonic bonding portion 20 is the relationship (1) (C ≦ 2A-E, A is the width of each current collecting tab, and E is laminated. The width of the entire current collecting tab).

As protective lead 5 of the positive electrode also satisfy the same conditions, it is preferably bonded by ultrasonic waves to the collector portion 7 ₃ of the positive electrode lead 7. As a result, the positive current collecting tab 3 having high strength is electrically connected to the positive output terminal 12 via the positive lead 7.

  As long as the conditions of the ultrasonic junction between the current collecting tab and the lead are satisfied, the battery in FIG. 8 can be variously modified. For example, in the above-described drawings, both the positive output terminal and the negative output terminal are rivets, but only the negative output terminal is a rivet, and the positive output terminal may be configured by a portion protruding in a convex shape on the outer surface of the lid 9. Good. Alternatively, only the positive electrode output terminal can be used as a rivet, and the portion protruding from the outer surface of the lid 9 can be used as a negative electrode output terminal.

  In the present invention, when ultrasonically bonding a plurality of current collecting tabs and leads, it is possible to reliably join only the region where all the current collecting tabs overlap so as not to cross the width end of the current collecting tabs. did. As a result, the strength of the current collecting tab can be increased, and problems such as tab cutting can be reduced, and a battery having excellent large current characteristics can be provided.

[Example]
Hereinafter, the present invention will be described in detail with reference to examples.

  Aluminum tab (1N30-H, thickness 0.015 mm, width 25 mm), protective lead (1050-O, thickness 0.2 mm, width 25 mm), and lead (1050-H, thickness 0.8 mm, width) 22 mm) was prepared.

  40 aluminum tabs were stacked and sandwiched between protective leads, and a test sample was prepared by joining the lead with ultrasonic waves using a horn and an anvil as shown in FIG. For ultrasonic bonding, an ultrasonic welding machine manufactured by Nippon Emerson Co., Ltd. was used. The tip angle of the horn of the ultrasonic welder was 90 °, and the joining was performed under the conditions of a pressurization time of 0.2 Mpa, an amplitude of 80%, and a time of 0.8 sec. As a result, a joint (horn mark) having a depth of 4 mm was formed, and the width of the joint was 8 mm.

  About the obtained sample, while measuring the gap | deviation width | variety of an aluminum tab, the tensile strength of each aluminum tab was measured.

  Here, the tab shift width will be described. The tab shift width B is defined by the distance from the center of the tab 35 to the center of the ultrasonic bonding portion 59. For example, as shown in FIG. 10, when the center of the tab 35 coincides with the center of the ultrasonic bonding portion 59, B = 0.

  Since the width (A) of the tab used here is 25 mm and the width (C) of the ultrasonic bonding portion is 8 mm, when the deviation width (B) of the tab is 8.5 mm, it is shown in FIG. As shown, the end of the joint 59 coincides with the width end of the tab 35.

  When the deviation width B is 12.5 mm, the center of the ultrasonic bonding portion 59 coincides with the width of the tab 35 as shown in FIG. That is, the joint part 59 exists on the outer side of the width end of the tab. In this tab, since the joined width is small, the strength is reduced.

  When the deviation width B is 16.5 mm, since the ultrasonic bonding portion 59 does not overlap with the current collecting tab 35, the current collecting tab is not bonded as shown in FIG.

  The tensile strength was measured by fixing the lead of the ultrasonically bonded sample and pulling 40 aluminum tabs one by one until cutting occurred. Forty aluminum tabs were 1, 2, 3... In order from the horn side, and the strength of each tab was examined. The results are shown below.

(Sample 1)
The width ends of the 40 tabs are aligned, and the aluminum tab 35 and the lead 41 are joined by the ultrasonic joining portion 59 as shown in FIG. All 40 aluminum tabs are bonded by ultrasonic waves, and the width C of the ultrasonic bonded portions satisfies (C ≦ 2A-E). The end of the joint portion 59 does not reach the width end of the tab 35. As shown in the graph of FIG. 15, the tensile strength is at a high level of about 26N at the minimum and about 45N at the maximum.

(Sample 2)
Although the width ends of the 40 tabs are aligned, the joint portion 59 is formed across the aluminum tab 35 as shown in FIG. The protruding width x of the joint portion 59 was 2 mm, and the tab shift width was 10.5 mm. The width C of the ultrasonic bonding portion satisfies (C ≦ 2A-E), but the bonding portion exceeds the width end of the tab. The tensile strength was significantly reduced as shown in the graph of FIG. 17, and was about 25 N at the maximum.

(Sample 3)
Although the 40 tabs are displaced, the ultrasonic bonding portion 59 does not cross the width end of the aluminum tab 35. FIG. 18 shows how the lead 41 and the aluminum tab 35 are joined. The width C of the ultrasonic bonding portion satisfied (C ≦ 2A-E), and all 40 tabs were bonded by ultrasonic waves.

  The tab tensile strength is shown in the graph of FIG. Of the 40 current collecting tabs, no. The deviation width of the tabs 1 to 8 is 8.5 mm. The deviation width of the tabs 9 to 16 is 6.5 mm, No. The deviation width of the tabs 17 to 24 is 4.5 mm. The deviation width of the tabs of 25 to 40 was 2.5 mm. The graph shown in FIG. 19 shows that even when the tab is displaced, a stable strength can be obtained at a relatively high level if the ultrasonic bonding portion is formed so as not to step on the width end of the tab. Is shown in

(Sample 4)
As shown in FIG. 20, the aluminum tab 35 is misaligned, and the joint 59 is formed across the width end of the aluminum tab. The width C of the joint is (C> 2A-E).

  The tensile strength of the tab is shown in the graph of FIG. Of the 40 current collecting tabs, no. The deviation width of the tabs 1 to 8 is 15 mm. The deviation width of the tabs 9 to 16 is 13 mm, The deviation width of the tabs 17 to 24 is 11 mm. The deviation width of the tabs 25 to 32 is 8.5 mm. The deviation width of the 33-40 tabs was 6.5 mm.

  As the displacement width increases, the protrusion of the joint also increases. The width of the protruding portion is No. For tabs 1 to 8, 6 mm, no. 9 to 16 tabs are 4 mm. 17 to 24 tabs were 2 mm.

  It can be seen that when the tab is displaced and the ultrasonic bonding portion is stepped on the width end of the tab, the tensile strength is lowered.

(Sample 5)
The width C of the ultrasonic bonded portion was (C> 2A-E), and as shown in FIG. 22, the horn side eight tabs were displaced. The tab shift width was 12.5 mm. The width ends of the eight tabs are stepped on the joint portion 59, and 4 mm of the joint portion 59 protrudes.

  It can be seen from the graph of FIG. 23 that the eight tabs with misalignment are insufficiently bonded due to the bonding portion stepping across the width end and crossing, resulting in poor tensile strength.

(Sample 6)
The width C of the ultrasonic bonded portion was (C> 2A-E), and as shown in FIG. 24, the eight tabs near the center were displaced. The tab shift width was 12.5 mm. The eight tabs are stepped at the joint 59 at the width end, and 4 mm of the joint protrudes.

  It can be seen from the graph of FIG. 25 that the eight tabs with misalignment are stepped on the joint and cross the width end, resulting in insufficient joining and poor tensile strength.

(Sample 7)
The width C of the ultrasonic bonded portion was (C> 2A-E), and as shown in FIG. 26, a deviation occurred in one tab near the center. The tab shift width was 12.5 mm. This tab is stepped at the junction 59 at the width end, and 4 mm of the junction protrudes.

  It can be seen from the graph of FIG. 27 that, in the tab where the displacement occurs, the joining portion becomes insufficient due to the stepping across the width end and the joining strength becomes insufficient, and the tensile strength decreases.

  Here, the relationship between the tab shift width and the average intensity is summarized in the graph of FIG. The strength tends to decrease as the tab shift width increases. However, if the condition (1) of the present invention is satisfied, the rate of decrease is relatively small. In FIG. 28, the above relationship (1) is established when the deviation width is 8.5 mm or less. That is, the strength can be ensured even if a deviation occurs by ultrasonically joining only the region where all the tabs exist without stepping across the width end of the tab.

  Since the strength of the tab is high, the possibility of cutting is reduced and an increase in resistance is avoided. It can be seen that the output is stable and excellent rapid filling characteristics and large current output characteristics can be obtained. According to the present invention, it has been confirmed that strength can be obtained with respect to an external force during incorporation of the electrode group into the container.

  Next, the current collecting tab and the protective lead lead were joined by applying the sample 3 described above to produce the battery of the example. The specific configuration is as follows.

The positive electrode has a current collector in which an active material-containing layer containing lithium cobalt oxide (LiCoO ₂ ), graphite powder as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder is made of aluminum or an aluminum alloy foil The sheet-like thing formed in both surfaces was used. On the other hand, the negative electrode includes a negative electrode active material powder having a lithium occlusion potential of 0.4 V or more with respect to the open circuit potential of lithium metal, carbon powder as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder. The sheet-like thing in which the active material content layer containing this was formed on both surfaces of the electrical power collector which consists of aluminum or aluminum alloy foil was used. The electrode group is produced by winding them in a spiral shape while interposing a separator between the positive electrode and the negative electrode, and then crushing and deforming the whole into a quadrangular cross-sectional shape that matches the cross-sectional shape of the metal container. Those having the structure shown in FIG. 1 were used.

  As the positive electrode current collector tab, a positive electrode current collector that was extended in a strip shape at a plurality of locations (in this case, 50 points) was used. In addition, a negative electrode current collector tab was used in which a plurality of negative electrode current collectors (in this case, extending in a band shape at 50 points. The current collector tab 50 for each of the positive electrode current collector tab and the negative electrode current collector tab). The leading ends of the sheets were overlapped and a protective lead was disposed, and the current collecting tab sandwiched between the protective leads and the lead were joined by ultrasonic waves using a horn and an anvil as shown in FIG.

  Subsequent steps were performed by a conventional method to obtain the battery of the example.

  Further, a battery of a comparative example was manufactured by the same method except that the joining state of the current collecting tab and the lead was changed to Sample 4.

  The obtained battery was dropped from a height of 10 cm, and a drop test was performed. This drop test was performed on all six sides with each side of the battery facing down. When this was repeated as one cycle, the battery of the example withstood 800 cycles. On the other hand, in the battery of the comparative example, there was a problem that the joint between the positive and negative electrode leads and the tab was detached in 200 cycles. In addition, the same effect was confirmed also in the drop test from 1 m.

  From these results, it can be seen that the present invention secures strength against external force after the battery is assembled.

  In the above-described embodiments, a battery using a non-aqueous electrolyte is described as an example. However, a battery using a solid electrolyte, a polymer electrolyte, or an aqueous electrolyte instead of the non-aqueous electrolyte can be naturally applied. Furthermore, the positive and negative electrode active materials are not limited to this, and other active materials can be used.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

1 ... container; 2 ... electrode group; 3 ... positive electrode current collector tab; 4 ... negative electrode current collector tab 5 ... protective lead; 6 ... protective lead; 7 ... positive lead; 8 ... negative lead 7 _1, 8 ₁ ... connection plate; 7 _2, 8 ₂ ... through-hole; 7 _3, 8 ₃ ... collecting part 9 ... lid; 10,11 ... gasket; 12 ... positive output terminal; 13 ... negative output terminals 14 and 15 ... insulator; 14 _1, 15 DESCRIPTION OF SYMBOLS ₁ ... Through-hole; 20 ... Junction by ultrasonic wave 21 ... Anvil; 22 ... Horn; 31 ... Container; 32, 33 ... Electrode group 32a, 33a ... Upper end surface; 36, 37 ... protective lead; 38 ... lid; 39 ... gasket; 40 ... negative electrode output terminal 41 ... negative electrode lead; 42 ... positive electrode lead; 43 ... positive electrode output terminal 51a, 51b ... spacer; 52a-52c ... partition plate; Protrusions 54a-54c Joint by 56 ... holes 59 ... ultrasonic; partition plate; 55 ... recess.

Claims (4)

An electrode group including a positive electrode and a negative electrode;
Wherein the group of electrodes positive electrode or the negative electrode and are electrically connected, Ri Do of aluminum or an aluminum alloy, a plurality of current collecting tabs are stacked with a positional deviation in the width end,
Protective leads sandwiching the plurality of current collecting tabs;
A battery comprising a plurality of current collecting tabs sandwiched between the protective leads and ultrasonically bonded to the lead made of aluminum or an aluminum alloy,
The battery is characterized in that the ultrasonic bonding portion is formed without crossing the width ends of any of the current collecting tabs constituting the plurality of current collecting tabs. 2. The battery according to claim 1, wherein a width C of the joint portion and a width E of the plurality of current collecting tabs satisfy the following relationship in a width direction of the plurality of current collecting tabs.
C ≦ 2A-E
(A is the width A of each current collecting tab constituting the plurality of current collecting tabs.)   2. The method of manufacturing a battery according to claim 1, wherein the plurality of current collecting tabs sandwiched between the protective leads so as not to cross a width end of any one of the current collecting tabs constituting the plurality of current collecting tabs. And the lead by ultrasonic bonding. The method according to claim 3, wherein the plurality of current collecting tabs sandwiched between the protective leads and the leads are joined by ultrasonic waves so as to satisfy the following relationship.
C ≦ 2A-E
(C is the width of the joint by ultrasonic waves, E is the width of the plurality of current collecting tabs, and A is the width A of each current collecting tab constituting the plurality of current collecting tabs.)

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