JPWO2013105361A1 - Ultrasonic welding tip, ultrasonic welding machine, and battery manufacturing method - Google Patents

Abstract

A plurality of protrusions are formed on the processed surface (11) of the tip (10) pressed against the member to be welded when ultrasonic welding is performed. When the processed surface is viewed from the front, at least one protrusion arranged on the outermost periphery among the plurality of protrusions is an arc having a radius R that satisfies R ≧ A / 6 when the outer dimension in one direction is A (121r) ) On the surrounding contour line (121). Thereby, it can reduce that a tear generate | occur | produces in the foil which is a to-be-welded member by ultrasonic welding.

Description

  The present invention relates to a tip for ultrasonic welding that is pressed against a member to be welded (so-called “workpiece”) and ultrasonically welds the member to be welded by applying ultrasonic vibration to the member to be welded. Moreover, this invention relates to the ultrasonic welding machine provided with the said chip | tip. Furthermore, this invention relates to the manufacturing method of the battery which has the process of performing ultrasonic welding using the said chip | tip.

  A non-aqueous electrolyte battery represented by a lithium ion secondary battery is widely used as a power source for portable devices such as a mobile phone and a notebook personal computer because of its high energy density. With higher performance of portable devices, further increase in capacity of lithium ion secondary batteries is being promoted. In order to further improve the energy density, a laminated lithium ion sheathed with a flexible laminate sheet in which a metal foil such as an aluminum foil is used as a core material and a heat-fusible resin film is laminated as an adhesive layer on its inner surface Secondary batteries are often used.

  As an electrode laminated body incorporated in a laminated lithium ion secondary battery, a sheet-like positive electrode and a sheet-like negative electrode are alternately laminated via a separator in general.

  FIG. 19 is a perspective plan view showing a schematic configuration of a general laminate-type lithium ion secondary battery 60. In FIG. 19, 61p is a positive electrode and 61n is a negative electrode. The positive and negative electrodes 61p and 61n each have a current collector made of metal foil as a base material layer. The substantially rectangular electrode portions 71p and 71n and the ear portions 62p protruding from one side of the electrode portions 71p and 71n. , 62n. In the electrode portions 71p and 71n, an electrode mixture layer containing an active material is applied and formed on both surfaces of the current collector, while no electrode mixture layer is applied and formed on the ear portions 62p and 62n. The positive electrode 61p and the negative electrode 61n are alternately stacked via the separator 66 to constitute an electrode stacked body 67. The ears 62p of the plurality of positive electrodes 61p are overlapped with each other and welded by lead tabs 63p and welds 64p. Similarly, the ears 62n of the plurality of negative electrodes 61n are overlapped with each other and welded by lead tabs 63n and welds 64n. In FIG. 19, 68 is an exterior housing the electrode laminate 67. The exterior 68 is composed of two laminate sheets (exterior materials) 69 having flexibility. The two laminate sheets 69 are heat-sealed and sealed by a heat seal part 69a along the outer peripheral edge.

  FIG. 20 is a cross-sectional view along the thickness direction showing a schematic configuration of the negative electrode weld 64n and the vicinity thereof. In FIG. 20, the illustration of the separator 66 and the laminate sheet 69 between the positive electrode 61p and the negative electrode 61n is omitted to simplify the drawing. In FIG. 20, 65p is a positive electrode current collector, 66p is a positive electrode mixture layer applied to both surfaces of the positive electrode current collector 65p, 65n is a negative electrode current collector, and 66n is applied to both surfaces of the negative electrode current collector 65n. Negative electrode mixture layer. A plurality of negative electrode current collectors 65n constituting the negative electrode ear portion 62n are superimposed on the negative electrode lead tab 63n, and these are integrally welded at the welding portion 64n. Although not shown, the configuration of the positive electrode weld 64p is substantially the same as that shown in FIG. 20 (see, for example, Patent Document 1).

  As the positive electrode current collector 65p, an aluminum foil with a thickness of about 15 μm is generally used, and as the positive electrode lead tab 63p, an aluminum thin plate with a thickness of about 200 μm is used. On the other hand, a copper foil having a thickness of about 10 μm is generally used as the negative electrode current collector 65n, and a nickel-plated copper thin plate having a thickness of about 200 μm is used as the negative electrode lead tab 63n.

  In general, ultrasonic welding is used to weld the current collectors 65p, 65n constituting the ears 62p, 62n and the lead tabs 63p, 63n at the welds 64p, 64n.

  The ultrasonic welding method will be described with reference to FIG. Although FIG. 21 shows a case where the negative electrode weld 64n is formed, the positive electrode weld 64p is substantially the same.

  As shown in FIG. 21, a plurality of negative electrode current collectors 65n constituting lead tabs 63n and ears 62n are sequentially stacked on the upper surface 51 of the anvil 50, and the chip 10 is placed on the negative electrode current collector 65n. While pressing the chip 10 against the negative electrode current collector 65n with the load F so as to compress the lead tab 63n and the negative electrode current collector 65n between the chip 10 and the anvil 50, the vibration is generated in a direction orthogonal to the direction of the load F. A sonic vibration S is applied to the chip 10. The ultrasonic vibration applied through the chip 10 heats the interfaces of the plurality of negative electrode current collectors 65n and the lead tabs 63n with frictional heat, thereby forming welds 64n (see FIGS. 19 and 20).

  A surface (hereinafter referred to as “processed surface”) 11 of the tip 10 that abuts against the negative electrode current collector 65n so that the energy of ultrasonic vibration is efficiently applied to the negative electrode current collector 65n and the lead tab 63n that are welded members. The surface 51 (hereinafter referred to as “holding surface”) 51 that contacts the lead tab 63n of the anvil 50 is formed with fine irregularities of a predetermined shape.

  22A is a plan view showing an example of the shape of the processed surface 11 of the chip 10, and FIG. 22B is a front view thereof. As shown in these drawings, a plurality of projections 910 having a quadrangular pyramid shape (a shape obtained by cutting off the top of the quadrangular pyramid along a plane parallel to the bottom surface) are vertically and horizontally formed on the processed surface 11. It is arranged in a grid in the direction. The plurality of protrusions 910 have the same shape and dimensions.

JP 2007-26945 A

  When the processed surface 11 of the chip 10 shown in FIGS. 22A and 22B is pressed against the negative electrode current collector 65n as shown in FIG. 21 to perform ultrasonic welding, depending on the ultrasonic welding conditions, the welded portion 64n or There may be a problem in that the negative electrode current collector 65n (particularly, the uppermost negative electrode current collector 65n with which the processed surface 11 abuts) is broken in the vicinity thereof. This will be described with reference to FIG.

  FIG. 23 is an enlarged plan view showing an example of a welded portion 64n formed by ultrasonic welding using the chip 10 having the processed surface 11 shown in FIGS. 22A and 22B. The processed surface 11 was in contact with the surface of the welded portion 64n shown in FIG. As shown in FIG. 23, a projection 910 (FIGS. 22A and 22B) on the processed surface 11 is formed on the uppermost negative electrode current collector 65n (hereinafter referred to as “the uppermost negative electrode current collector 65n”). The welding mark 920 which is a substantially quadrangular frustum-shaped concave portion is formed by being pressed.

  930 is a tear generated in the uppermost negative electrode current collector 65n by ultrasonic welding. The tear 930 is likely to occur in the vicinity of the welding marks 920 arranged at the peripheral portion, particularly at the four corners, among the plurality of welding marks 920 arranged in a lattice shape.

  As can be understood from FIG. 21, the ear portion 62n is thinner than the electrode portion because the mixture layer 66n is not formed. Since the plurality of negative electrode current collectors 65n constituting such thin ear portions 62n are bundled in the thickness direction between the chip 10 and the lead tab 63n, tension is easily applied to the negative electrode current collector 65n. . By pressing the protrusion 910 of the processed surface 11 against such a negative electrode current collector 65n, particularly the uppermost negative electrode current collector 65n is locally extended along the shape of the protrusion 910. Therefore, in the uppermost negative electrode current collector 65n, it is considered that the tear 930 is likely to occur at a position in the vicinity of the welding mark 920 in the peripheral portion where the largest tension is easily applied among the plurality of welding marks 920.

  In addition, although the unevenness | corrugation is formed also in the holding surface 51 of the anvil 50, since the lead tab 63n with which the holding surface 51 contacts is thicker than the negative electrode current collector 65n, the lead tab 63n is hardly broken.

  If the load F (see FIG. 21) of the chip 10 is reduced, the frequency of occurrence of the tear 930 is reduced, but the energy of ultrasonic vibration is not sufficiently applied to the negative electrode current collector 65n and the lead tab 63n. Prone to occur.

  Therefore, in order to suppress the generation of the break 930, conventionally, (1) a rolled copper foil having relatively excellent elongation resistance is used as the copper foil constituting the negative electrode current collector 65n. A “dummy thin plate / a plurality of negative electrode current collectors 65n / lead tabs 63n” is integrally ultrasonically welded with a copper dummy thin plate having substantially the same thickness as the lead tab 63n interposed between the negative electrode current collector 65n and the negative tab current collector 65n. Measures have been taken, such as making it difficult to form weld marks 920 on the uppermost negative electrode current collector 65n.

  However, the method using a rolled copper foil has a problem that the rolled copper foil is more expensive than the electrolytic copper foil. In addition, the method of welding the dummy thin plates together has a problem that the dummy thin plate needs to be prepared, and thus there is a problem that the cost is high, a problem that the ultrasonic welding work is complicated, and a problem that the welded portion 64n is thick. .

  The above-mentioned problem that the current collector is broken by ultrasonic welding is likely to occur in the negative electrode current collector having a relatively thin thickness, but the same applies to the positive electrode current collector depending on the ultrasonic welding conditions. May occur. Also, in fields other than batteries, the same phenomenon may occur when the chip 10 is pressed against a thin metal foil and ultrasonic welding is performed.

  The breakage of the current collector may adversely affect the voltage characteristics of the finally obtained lithium ion secondary battery. Therefore, tearing reduces the manufacturing yield of the battery and also reduces the reliability of the battery.

  An object of the present invention is to provide an ultrasonic welding tip and an ultrasonic welding machine in which a foil that is a member to be welded hardly breaks. Another object of the present invention is to provide a battery manufacturing method in which the current collectors constituting the ears are less likely to be broken when the electrode ears and the lead tabs are ultrasonically welded.

  The tip for ultrasonic welding of the present invention has a processed surface on which a plurality of protrusions are formed, and applies ultrasonic vibration to the member to be welded while pressing the processed surface against the member to be welded. An ultrasonic welding tip for ultrasonic welding, when the processed surface is viewed from the front, at least one of the plurality of protrusions arranged on the outermost periphery has an outer dimension in one direction. It is a chamfering protrusion chamfered so as to have an arc having a radius R satisfying R ≧ A / 6 on the surrounding contour line when A.

  An ultrasonic welding machine of the present invention includes a tip that is pressed against a member to be welded to apply ultrasonic vibrations to the member to be welded, and an anvil that is disposed to face the tip and supports the member to be welded. And a horn that is provided at one end and resonates by the ultrasonic vibration. And the said chip | tip is a chip | tip for ultrasonic welding of said this invention.

  The battery manufacturing method of the present invention has a current collector as a base material layer, an electrode portion in which an electrode mixture layer is formed in a predetermined region of the current collector, and the electrode mixture layer is not formed A step of laminating a plurality of electrodes each having an ear portion, and a step of ultrasonically welding the ear portion of the plurality of electrodes and a lead tab thicker than the current collector. Then, in the ultrasonic welding step, the processed surface of the ultrasonic welding tip of the present invention is pressed against the ear portion to ultrasonically weld the ear portion and the lead tab.

  According to the ultrasonic welding tip and the ultrasonic welding machine of the present invention, since at least one projection arranged on the outermost periphery among the plurality of projections formed on the processing surface of the tip is a chamfering projection, stress is applied to the foil. Concentration hardly occurs. Therefore, the tearing of the foil by ultrasonic welding can be reduced.

  Further, according to the battery manufacturing method of the present invention, the above-described ultrasonic welding tip of the present invention is pressed against the ear portion of the electrode to weld the electrode ear portion and the lead tab. The tear which arises in the electrical power collector which comprises can be reduced. Therefore, a highly reliable battery can be stably manufactured with a high yield. Moreover, it becomes possible to use the electrolytic copper foil which was difficult to use conventionally as a collector. Further, it is not necessary to perform ultrasonic welding with a dummy thin plate sandwiched between the tip and the ear.

FIG. 1 is a diagram showing a schematic configuration of an example of an ultrasonic welder according to the present invention. FIG. 2A is a plan view of a processed surface of a tip according to Embodiment 1 of the present invention used in an ultrasonic welding machine, and FIG. 2B is a front view thereof. FIG. 3A is an enlarged plan view of non-chamfered protrusions arranged at the corners other than the four corners among the plurality of protrusions formed on the processed surface of the chip shown in FIGS. 2A and 2B, and FIG. 3B is a line 3B-3B in FIG. 3A. It is an arrow expanded sectional view of the non-beveling protrusion along. 4A is an enlarged plan view of chamfered protrusions arranged at four corners among the plurality of protrusions formed on the processed surface of the chip shown in FIGS. 2A and 2B, and FIG. 4B is along the line 4B-4B in FIG. 4A. It is an arrow expanded sectional view of a chamfering protrusion. FIG. 5 is an enlarged plan view showing a weld portion formed by ultrasonic welding using the tip shown in FIGS. 2A and 2B. FIG. 6 is a plan view showing an arrangement of a plurality of protrusions formed on the processing surface of another tip used in the ultrasonic welding machine according to the first embodiment of the present invention. FIG. 7 is a plan view showing an arrangement of a plurality of protrusions formed on the processing surface of the tip used in the ultrasonic welding machine according to the second embodiment of the present invention. FIG. 8 is a plan view showing an arrangement of a plurality of protrusions formed on the processing surface of the tip used in the ultrasonic welding machine according to the third embodiment of the present invention. FIG. 9A is a plan view of a processed surface of a tip according to Embodiment 4 of the present invention used in an ultrasonic welding machine, and FIG. 9B is a front view thereof. 10A is an enlarged plan view of chamfered protrusions arranged at four corners among the plurality of protrusions formed on the processed surface of the chip shown in FIGS. 9A and 9B, and FIG. 10B is along the line 10B-10B in FIG. 10A. It is an arrow expanded sectional view of a chamfering protrusion. FIG. 11 is an enlarged plan view showing a welded portion formed by ultrasonic welding using the tip shown in FIGS. 9A and 9B. 12A is an enlarged plan view of another chamfering protrusion formed on the processing surface of the tip used in the ultrasonic welding machine according to Embodiment 4 of the present invention, and FIG. 12B is a chamfering protrusion along the line 12B-12B in FIG. 12A. FIG. FIG. 13A is a cross-sectional view of a chamfered protrusion formed on a processed surface of a tip used in an ultrasonic welder according to Embodiment 5 of the present invention. FIG. 13B is an enlarged cross-sectional view of the portion 13B of FIG. 13A. FIG. 14A is a plan view of a welding mark formed by the chamfered protrusion shown in FIGS. 13A and 13B. 14B is a cross-sectional view of the weld mark taken along the line 14B-14B in FIG. 14A. FIG. 14C is an enlarged cross-sectional view of the portion 14C of FIG. 14B. FIG. 15A is a cross-sectional view of another chamfering protrusion formed on the processed surface of the tip used in the ultrasonic welding machine according to the fifth embodiment of the present invention. FIG. 15B is an enlarged cross-sectional view of the portion 15B of FIG. 15A. FIG. 16A is a cross-sectional view of still another chamfering protrusion formed on the processing surface of the tip used in the ultrasonic welding machine according to the fifth embodiment of the present invention. FIG. 16B is an enlarged cross-sectional view of the portion 16B of FIG. 16A. 17A is a cross-sectional view of the chip taken along the line 17A-17A in FIG. 2A. FIG. 17B is a cross-sectional view of the chip taken along the line 17B-17B in FIG. 2A. FIG. 17C is an enlarged plan view of a portion 17C of FIG. 2A. FIG. 18 is a diagram showing the results of Examples and Comparative Examples in Evaluation Test 2. FIG. 19 is a perspective plan view showing a schematic configuration of a general laminated lithium ion secondary battery. FIG. 20 is a cross-sectional view showing a schematic configuration of a welded portion between the ear portion of the negative electrode and the REIT tab and the vicinity thereof in the laminated lithium ion secondary battery shown in FIG. FIG. 21 is a side view showing an ultrasonic welding method for forming the weld shown in FIG. FIG. 22A is a plan view showing an example of the shape of a processed surface of a conventional tip used for ultrasonic welding, and FIG. 22B is a front view thereof. FIG. 23 is an enlarged plan view showing an example of a welded portion formed by ultrasonic welding using a chip having the processed surface shown in FIGS. 22A and 22B.

  The ultrasonic welding tip of the present invention includes a processed surface on which a plurality of protrusions are formed. The tip is used for applying ultrasonic vibration to the member to be welded while pressing the processed surface against the member to be welded to ultrasonically weld the member to be welded. When the processed surface is viewed from the front, at least one protrusion arranged on the outermost periphery among the plurality of protrusions is an arc having a radius R that satisfies R ≧ A / 6 when the outer dimension in one direction is A. Is a chamfered projection chamfered so as to have a peripheral contour line.

  In the above-described ultrasonic welding tip of the present invention, the plurality of protrusions are arranged in a lattice shape, and at least one of the four protrusions arranged at four corners of the plurality of protrusions is the chamfered protrusion. It is preferable. As a result, the chamfered protrusions can be disposed in the vicinity of locations where tearing is particularly likely to occur, so that the tearing of the foil can be effectively reduced.

  Preferably, the plurality of protrusions are arranged in a lattice pattern, and all of the four protrusions arranged at four corners of the plurality of protrusions are the chamfered protrusions. As a result, chamfered protrusions can be arranged at the four corners where breakage is particularly likely to occur, so that the tearing of the foil can be further reduced.

  It is preferable that all the protrusions arranged on the outermost periphery among the plurality of protrusions are the chamfered protrusions. Thereby, tearing of the foil can be further reduced.

  It is preferable that all of the plurality of protrusions are the chamfered protrusions. This minimizes the possibility of foil tearing.

  When the processed surface is viewed from the front, the contour line of the chamfered protrusion may be a substantially square shape having the arcs having a radius R at four corners. In this case, it is preferable that the distance between two opposite sides of the substantially square is the dimension A. Thereby, a chamfering protrusion can be formed by adding a slight processing to a quadrangular frustum-shaped protrusion (non-chamfered protrusion) formed on the processed surface of a conventional chip.

  Or when the said processed surface is seen from the front, the said outline of the said chamfering protrusion may be circular. In this case, the circular diameter may be the dimension A. Thereby, tearing of the foil can be further reduced.

  It is preferable that a concave curved surface that smoothly connects the flat surface of the processed surface and the chamfered protrusion is formed along the contour line of the chamfered protrusion. Thereby, tearing of the foil can be further reduced.

  In the above case, the radius of curvature of the concave curved surface is preferably 0.1 mm or more. Thereby, tearing of the foil can be further reduced.

  It is preferable that chamfering is performed on an outer peripheral end of the processed surface where the processed surface and a side surface adjacent to the processed surface intersect. Thereby, tearing of the foil can be further reduced.

  It is preferable that at least one of the four corner portions of the processed surface is chamfered. More preferably, all four corner portions are chamfered. Thereby, tearing of the foil can be further reduced.

  It is preferable that the chamfering of the outer peripheral end of the processing surface and the chamfering of the corner portion of the processing surface have a substantially cylindrical surface shape with a radius of 0.5 mm or more. Thereby, tearing of the foil can be further reduced.

  The battery manufacturing method of the present invention has a current collector as a base material layer, an electrode portion in which an electrode mixture layer is formed in a predetermined region of the current collector, and the electrode mixture layer is not formed A step of laminating a plurality of electrodes each having an ear portion, and a step of ultrasonically welding the ear portion of the plurality of electrodes and a lead tab thicker than the current collector. Then, in the ultrasonic welding step, the processed surface of the ultrasonic welding tip of the present invention is pressed against the ear portion to ultrasonically weld the ear portion and the lead tab.

  In the method for producing a battery of the present invention, the current collector is preferably an electrolytic copper foil. Thereby, since the electrolytic copper foil is cheaper than the rolled copper foil, the cost of the battery can be reduced.

  Below, this invention is demonstrated in detail, showing suitable embodiment and an Example. However, it goes without saying that the present invention is not limited to the following embodiments and examples. For convenience of explanation, the drawings referred to in the following description show only the main members necessary for explaining the present invention in a simplified manner among the members constituting the embodiment of the present invention. Therefore, the present invention can include any member not shown in the following drawings. Moreover, the dimension of the member in each following figure does not represent the dimension of an actual member, the dimension ratio of each member, etc. faithfully. In each figure, corresponding members are denoted by the same reference numerals, and redundant description thereof is omitted.

  FIG. 1 shows a schematic configuration of an ultrasonic welding machine 1 according to the present invention. The ultrasonic welder 1 includes a transmitter 2 that outputs an electrical signal having a predetermined frequency in the ultrasonic band, and a transducer that converts the electrical signal from the transmitter 2 into mechanical vibration in the ultrasonic band. 3, a booster 4 that converts the mechanical vibration generated by the vibrator 3 into ultrasonic vibration of a predetermined amplitude, a horn 5 that resonates due to the ultrasonic vibration from the booster 4, and a chip provided at one end of the horn 5 10 and an anvil 50 arranged to face the chip 10. The member to be welded is placed on the holding surface 51 of the anvil 50 and supported by the anvil 50. The processed surface 11 of the tip 10 is pressed against the member to be welded on the anvil 50, and a predetermined ultrasonic vibration is applied to the member to be welded through the tip 10.

  The configuration of the ultrasonic welding machine 1 of the present invention is not particularly limited, except for the shape of the processed surface 11 pressed against the member to be welded of the chip 10 described later. For example, the present invention can be applied to any known ultrasonic welding machine. The chip 10 and the horn 5 may be constituted by one integrated part or may be constituted by separate parts.

(Embodiment 1)
FIG. 2A is a plan view of the machining surface 11 of the chip 10 according to the first embodiment of the present invention used in the ultrasonic welding machine 1, and FIG. 2B is a front view thereof. Similar to the processed surface 11 of the conventional chip 10 shown in FIGS. 22A and 22B, the processed surface 11 of the chip 10 of the first embodiment is a flat surface, and 16 protrusions are formed on the processed surface 11 in two rows × It is arranged in a grid in 8 rows. Of the 16 protrusions, the four protrusions 120 arranged at the four corners have the same shape and dimensions, and the remaining 12 protrusions 110 have the same shape and dimensions.

  FIG. 3A is an enlarged plan view of the protrusion 110 arranged at other than the four corners, and FIG. 3B is an enlarged cross-sectional view of the protrusion 110 taken along line 3B-3B in FIG. 3A. The protrusion 110 has a quadrangular pyramid shape (a shape obtained by cutting off the top of the quadrangular pyramid along a plane parallel to its bottom surface), and the processed surface 11 of the conventional chip 10 shown in FIGS. 22A and 22B. It has substantially the same shape as the protrusion 910 formed on the surface. That is, when the projection 110 is viewed in plan as shown in FIG. 3A, the contour line 111 around the projection 110 (that is, the plan view shape of the bottom surface of the projection 110) is a square whose side is A. The outline 113 around the upper surface 112 of the protrusion 110 is also square. However, minute chamfers may be formed at the four corners of the contour line 111 and / or the contour line 113. An inclined surface 114 is formed so as to connect the contour line 111 and the contour line 113.

  4A is an enlarged plan view of the protrusion 120 arranged at the four corners of the 16 protrusions shown in FIG. 2A, and FIG. 4B is an enlarged cross-sectional view of the protrusion 120 taken along line 4B-4B of FIG. 4A. The protrusion 120 has substantially the same shape as the four ridge lines 115 (see FIG. 3A) of the inclined surface 114 of the protrusion 110 having the quadrangular frustum shape shown in FIGS. 3A and 3B chamfered into a substantially cylindrical shape. Have. More specifically, as shown in FIG. 4A, the contour line 121 around the protrusion 120 (that is, the shape of the bottom surface of the protrusion 120 in a plan view) 121 is a square corner having a distance A between two opposite sides. Is a substantially square chamfered by an arc 121r having a radius R. The distance A between the two opposite sides and the radius R satisfy R ≧ A / 6. The value of the radius R can be appropriately changed depending on the size of the protrusion 120 and the like, but is preferably 0.2 mm or more, and more preferably 0.3 mm or more. The outline 123 around the upper surface 122 of the protrusion 120 is also a substantially square with four corners chamfered in an arc shape. An inclined surface 124 is formed so as to connect the contour line 121 and the contour line 123. Therefore, the four ridge lines 125 of the inclined surface 124 are configured by smooth convex curved surfaces (for example, a part of a cylindrical surface).

  In the present invention, the protrusion 120 having an arc-shaped chamfered periphery as shown in FIGS. 4A and 4B is called a “chamfered protrusion”, and the arc-shaped chamfer as shown in FIGS. 3A and 3B is substantially the same. The protrusions 110 that are not provided are called “non-chamfered protrusions”, and the two protrusions are distinguished by the difference in shape.

  The chip 10 of the present embodiment having the processed surface 11 on which the protrusions 110 and 120 are formed as described above is used, for example, when ultrasonically welding the electrode tab and the lead tab of the laminated lithium ion secondary battery. be able to. That is, the tip 10 of Embodiment 1 can be used as the tip 10 shown in FIG. 21 showing the ultrasonic welding method. The processed surface 11 of the chip 10 is pressed against the upper surface of the uppermost negative electrode current collector 65n.

  FIG. 5 is an enlarged plan view showing a welded portion 64n formed by ultrasonic welding 1 using the tip 10 according to the first embodiment. The processed surface 11 was in contact with the surface of the weld 64n shown in FIG. As shown in FIG. 5, concave welding marks 210 and 220 formed by pressing the projections 110 and 120 of the processed surface 11 are formed on the uppermost negative electrode current collector 65n. . The welding mark 210 is formed by the protrusion 110, and is a concave portion having a substantially quadrangular truncated pyramid shape, like the welding mark 920 shown in FIG. On the other hand, the weld mark 220 is formed by the protrusion 120. As can be understood by comparison with the welding mark 210, the outline 221 of the welding mark 220 is a substantially square in which arc-shaped chamfers having relatively large radii are formed at the four corners. As can be easily understood from the difference in the shape of the weld mark 210 and the weld mark 220, the arc chamfering of the outline 221 of the weld mark 220 causes the stress concentration generated in the negative electrode current collector 65n in the vicinity of the weld mark 220. To ease. Therefore, the chamfered protrusion 120 that forms the weld mark 220 has a shape that is more advantageous for reducing the stress concentration generated in the negative electrode current collector 65n near the weld mark than the protrusion 110 that forms the weld mark 210. .

  As described with reference to FIG. 23, in the conventional ultrasonic welding method, a tear 930 is generated in the vicinity of the peripheral portion to which the largest tension is applied, particularly in the vicinity of the welding marks 920 at the four corners. On the other hand, in the first embodiment, the projections at the four corners among the plurality of protrusions arranged in a lattice shape are the chamfered protrusions 120 that do not easily cause stress concentration in the negative electrode current collector 65n. The generation of the 65n break 930 can be effectively suppressed.

  Since it is difficult for the negative electrode current collector 65n to be broken 930, an inexpensive electrolytic copper foil can be used as the negative electrode current collector 65n. Therefore, the cost of the battery 60 can be reduced. Further, unlike the prior art, there is no need for ultrasonic welding with a dummy thin plate sandwiched between the chip 10 and the uppermost negative electrode current collector 65n.

  In the above example, the example in which the protrusions are arranged in 2 rows × 8 columns on the processed surface 11 is shown, but the arrangement of the protrusions is not limited to this. As shown in FIG. 6, the protrusions may be arranged in a grid of m rows × n columns (m and n are integers of 2 or more). In this case, the four protrusions arranged at the four corners can be the chamfered protrusions 120, and the other protrusions can be the non-chamfered protrusions 110. In this case, the same effect as the above example can be obtained.

  2A and 6, only some of the four protrusions arranged at the four corners may be chamfered protrusions 120, and all the other protrusions may be non-chamfered protrusions 110. By arranging the chamfered protrusion 120 only in the vicinity of a portion where the tear 930 is likely to occur, the occurrence of the tear 930 can be effectively prevented.

  Alternatively, at least one of the protrusions arranged on the outermost periphery (in the example of FIG. 6, the protrusions arranged in the first row, the m-th row, the first column, and the n-th column) is used as the chamfering projection 120, All the projections other than those may be non-chamfered projections 110. In some cases, the portion where the tear 930 is likely to occur is other than the vicinity of the four corners. In such a case, the chamfered protrusion 120 is disposed only in the vicinity of the portion where the tear is likely to occur, so Can be prevented.

(Embodiment 2)
The second embodiment is different from the first embodiment regarding the arrangement of the protrusions formed on the processed surface 11 of the chip 10. Hereinafter, the second embodiment will be described with a focus on differences from the first embodiment.

  FIG. 7 is a plan view showing the arrangement of a plurality of protrusions formed on the processed surface 11 of the chip 10 of the second embodiment. Similar to FIG. 6, the processed surface 11 has protrusions arranged in a grid of m rows × n columns. However, unlike FIG. 6, the protrusions arranged on the outermost periphery (that is, the protrusions arranged in the first row, m-th row, first column, and n-th column) are all chamfered projections 120, and the other projections Is a non-chamfered protrusion 110.

  According to the second embodiment, stress concentration is unlikely to occur in the negative electrode current collector 65n at any location around the protrusion group arranged in m rows × n columns, so that the effect of preventing the generation of the tear 930 is prevented. Is further improved.

(Embodiment 3)
The third embodiment is different from the first and second embodiments with respect to the arrangement of the protrusions formed on the processed surface 11 of the chip 10. Hereinafter, the third embodiment will be described focusing on differences from the first and second embodiments.

  FIG. 8 is a plan view showing the arrangement of a plurality of protrusions formed on the processed surface 11 of the chip 10 of the third embodiment. Similar to FIGS. 6 and 7, the processed surface 11 has protrusions arranged in a grid of m rows × n columns. However, unlike FIGS. 6 and 7, all the protrusions (m × n protrusions) are the chamfered protrusions 120, and the non-chamfered protrusions 110 do not exist.

  According to the third embodiment, since all the projections are the chamfered projections 120, stress concentration is unlikely to occur in the negative electrode current collector 65n at any location of the projection group arranged in m rows × n columns. . Therefore, the effect of preventing the occurrence of the tear 930 is further improved.

(Embodiment 4)
In the fourth embodiment, a chamfered protrusion 130 having a shape different from the chamfered protrusion 120 shown in the first to third embodiments is used. Hereinafter, the fourth embodiment will be described focusing on differences from the first to third embodiments.

  FIG. 9A is a plan view of the machining surface 11 of the tip 10 according to Embodiment 4 of the present invention used in the ultrasonic welding machine 1, and FIG. 9B is a front view thereof. Similar to the processing surface 11 of the chip 10 of the first embodiment shown in FIGS. 2A and 2B, 16 protrusions are arranged in a grid in 2 rows × 8 columns on the processing surface 11 of the chip 10 of the fourth embodiment. Has been. Of the 16 protrusions, the four protrusions 130 arranged at the four corners have the same shape and dimensions, and the remaining 12 protrusions 110 have the same shape and dimensions.

  10A is an enlarged plan view of the chamfered protrusion 130 arranged at the four corners of the 16 protrusions shown in FIG. 9A, and FIG. 10B is an enlarged cross-sectional view of the chamfered protrusion 130 taken along the line 10B-10B in FIG. 10A. It is. The protrusion 130 has a smooth convex curved surface that swells in a dome shape. The convex curved surface may be an accurate spherical surface or an aspherical surface obtained by slightly deforming the convex spherical surface. As shown in FIG. 10A, the contour line 131 around the protrusion 130 (that is, the shape of the bottom surface of the protrusion 130 in a plan view) 131 is a circle having a diameter A. That is, the outline 131 of the protrusion 130 corresponds to the case where the radius R of the arc 121r at the four corners is set to half of the dimension A (R = A / 2) in the outline 121 of the protrusion 120 shown in FIG. 4A.

  FIG. 11 is an enlarged plan view showing a welded portion 64n formed by ultrasonic welding 1 using the tip 10 according to the fourth embodiment. The processed surface 11 was in contact with the surface of the weld 64n shown in FIG. As shown in FIG. 11, concave welding marks 210 and 230 formed by pressing the protrusions 110 and 130 on the processed surface 11 are formed on the uppermost negative electrode current collector 65n. . The welding mark 210 is formed by the protrusion 110, and is a concave portion having a substantially quadrangular truncated pyramid shape similar to the welding mark 210 shown in FIG. On the other hand, the welding mark 230 is a curved concave portion formed by the protrusion 130, and its outline 231 is substantially circular. The substantially circular outline 231 alleviates the stress concentration generated in the negative electrode current collector 65 n in the vicinity of the welding mark 230. Therefore, the chamfered protrusion 130 of the fourth embodiment that forms the welding mark 230 has a shape that is advantageous for reducing the stress concentration generated in the negative electrode current collector 65 n in the vicinity of the welding mark 230. Since the chamfered protrusion 130 of the fourth embodiment has a circular outline 131, a greater stress concentration relaxation effect can be obtained as compared to the chamfered protrusion 120 shown in the first to third embodiments.

  Although the chamfering protrusion 130 shown in FIGS. 10A and 10B has a smooth convex curved surface swelled in a dome shape, the present invention is not limited to this. Instead of the chamfered protrusion 130, for example, a chamfered protrusion 140 having a truncated cone shape (a shape obtained by cutting off the top of the cone along a plane parallel to the bottom surface) shown in FIGS. 12A and 12B or a shape similar to this is used. You can also As shown in FIG. 12A, the contour line around the protrusion 140 (that is, the shape of the bottom surface of the protrusion 140 in a plan view) 141 is a circle having a diameter A. Even when the chamfered protrusion 140 is used, the stress concentration generated in the negative electrode current collector 65n can be reduced.

  As described above, according to the fourth embodiment, the protrusions at the four corners among the plurality of protrusions arranged in a lattice shape are the chamfered protrusions 130 and 140 that do not easily cause stress concentration in the negative electrode current collector 65n. Generation | occurrence | production of the tear 930 of the negative electrode collector 65n can be suppressed effectively.

  In the above example, the example in which the projections at the four corners of the 2 rows × 8 columns of projections (see FIGS. 9A and 9B) arranged on the processed surface 11 are the chamfered projections 130 and 140 is shown. It is not limited to this. For example, various arrangement examples of the chamfering protrusions 120 described in the first to third embodiments can be applied to the arrangement of the chamfering protrusions 130 and 140.

(Embodiment 5)
FIG. 13A is a cross-sectional view of a chamfered protrusion 120 ′ according to the fifth embodiment. FIG. 13B is an enlarged cross-sectional view of the portion 13B of FIG. 13A. The chamfering protrusion 120 ′ of the fifth embodiment is a chamfering protrusion 120 having a substantially quadrangular frustum shape shown in FIGS. 4A and 4B in that the concave curved surface 121c is continuously formed along the contour line 121 thereof. And different. The concave curved surface 121c smoothly connects the inclined surface 124 and the flat upper surface of the processed surface 11 of the chip 10. Although not shown, the concave curved surface 121c smoothly connects the ridgeline 125 (see FIG. 4A), which is a smooth convex curved surface, and the processed surface 11 as well. The concave curved surface 121c is continuous in an annular shape so as to surround the chamfered protrusion 120 ′. The planar view shape of the chamfered protrusion 120 ′ is substantially the same as the planar view shape of the chamfered protrusion 120 (see FIG. 4A).

  FIG. 14A is a plan view of a welding mark 220 ′ formed on the upper surface of the uppermost negative electrode current collector 65 n when the chamfered protrusion 120 ′ is pressed against the negative electrode current collector 65 n. FIG. 14B is a cross-sectional view of the welding mark 220 ′ taken along the line 14 </ b> B- 14 </ b> B in FIG. 14A. FIG. 14C is an enlarged cross-sectional view of the portion 14C of FIG. 14B. The welding mark 220 'is a substantially quadrangular frustum-shaped recess. The bottom surface 222 of the welding mark 220 ′ is formed by transferring the upper surface 122 of the protrusion 120 ′, and the inclined surface 224 that connects the contour line 223 of the bottom surface 222 and the contour line 221 of the welding mark 220 ′ is the inclination of the protrusion 220 ′. The surface 124 is formed by being transferred. The shape of the weld mark 220 ′ is substantially the same as the weld mark 220 (see FIG. 5) formed by the chamfered protrusion 120. However, the welding mark 220 ′ is different from the welding mark 220 in that a smooth convex curved surface 221 c is formed along the outline 221. The convex curved surface 221c smoothly connects the inclined surface 224 and the upper surface of the uppermost negative electrode current collector 65n. The convex curved surface 221c is continuous in an annular shape so as to surround the welding mark 220 '. The convex curved surface 221c is formed by transferring the concave curved surface 121c of the chamfered protrusion 120 '. As shown in FIG. 14C, the cross-sectional shape of the convex curved surface 221c has a substantially arc shape.

  According to the present embodiment, since the concave curved surface 121c is formed along the contour line 121 of the chamfered protrusion 120 ′, the contour line 221 is formed on the welding mark 220 ′ formed by transferring the chamfered protrusion 120 ′. A convex curved surface 221c to which the concave curved surface 121c is transferred can be formed. The convex curved surface 221c relieves stress concentration generated in the negative electrode current collector 65n at and near the contour 221. Therefore, the chamfered protrusion 120 ′ having the concave curved surface 121 c can further reduce the occurrence of the break 930 of the negative electrode current collector 65 n compared to the chamfered protrusion 120 having no concave curved surface 121 c.

  A concave curved surface similar to the concave curved surface 121c can be applied to the chamfered protrusions 130 and 140 described in the fourth embodiment.

  15A and 15B show an example in which a concave curved surface is applied to the chamfering protrusion 130 having a smooth convex curved surface swelled in a dome shape shown in FIGS. 10A and 10B. 15A is a cross-sectional view of the chamfered protrusion 130 ′, and FIG. 15B is an enlarged cross-sectional view of the portion 15 </ b> B of FIG. 15A including the outline 131. A concave curved surface 131c is formed along the contour 131 of the chamfered protrusion 130 '. The concave curved surface 131 c smoothly connects the smooth convex curved surface of the protrusion 130 ′ and the flat upper surface of the processed surface 11 of the chip 10. The concave curved surface 131c is continuous in an annular shape so as to surround the chamfered protrusion 130 '. The chamfered protrusion 130 ′ is the same as the chamfered protrusion 130 except that the concave curved surface 131 c is formed. The planar view shape of the chamfered protrusion 130 ′ is substantially the same as the planar view shape of the chamfered protrusion 130 (see FIG. 10A).

  An example in which a concave curved surface is applied to the chamfered protrusion 140 having a substantially truncated cone shape shown in FIGS. 12A and 12B is shown in FIGS. 16A and 16B. 16A is a cross-sectional view of the chamfered protrusion 140 ′, and FIG. 16B is an enlarged cross-sectional view of the portion 16 </ b> B of FIG. 16A including the outline 141. A concave curved surface 141c is formed along the contour line 141 of the chamfered protrusion 140 '. The concave curved surface 141 c smoothly connects the conical surface of the protrusion 140 ′ and the flat upper surface of the processed surface 11 of the chip 10. The concave curved surface 141c is continuous in an annular shape so as to surround the chamfered protrusion 140 '. The chamfering protrusion 140 ′ is the same as the chamfering protrusion 140 except that the concave curved surface 141 c is formed. The planar view shape of the chamfered protrusion 140 ′ is substantially the same as the planar view shape of the chamfered protrusion 140 (see FIG. 12A).

  Although illustration is omitted, as in the case of the chamfered protrusions 120 ′, when the chamfered protrusions 130 ′ and 140 ′ are pressed against the negative electrode current collector and ultrasonic welding is performed, an upper surface of the uppermost negative electrode current collector is formed. A smooth convex curved surface in which the concave curved surfaces 131c and 141c are transferred can be formed on the contour line of the welding mark. The convex curved surface relieves stress concentration generated in the negative electrode current collector at the contour line and in the vicinity thereof. Therefore, the chamfered protrusions 130 ′ and 140 ′ having the concave curved surfaces 131 c and 141 c further reduce the occurrence of the break 930 of the negative electrode current collector 65 n compared to the chamfered protrusions 130 and 140 not having the concave curved surfaces 131 c and 141 c. Can do.

As shown in FIGS. 13B, 15B, and 16B, the shapes of the concave curved surfaces 121c, 131c, and 141c along the cross-sections passing through the contour lines 121, 131, and 141 of the chamfered protrusions 120 ′, 130 ′, and 140 ′ are as follows. A substantially arc shape is preferable. The curvature radii R ₁₂₁ , R ₁₃₁ , and R ₁₄₁ of the concave curved surfaces 121c, 131c, and 141c in the cross section are preferably 0.1 mm or more, more preferably 0.15 mm or more, 0.4 mm or less, and further 0 It is preferable that it is 3 mm or less. Here, the cross section defining the curvature radii R ₁₂₁ , R ₁₃₁ , and R ₁₄₁ is perpendicular to the tangent line of the contour lines ₁₂₁ , ₁₃₁ , and ₁₄₁ at the points where the cross sections intersect on the contour lines ₁₂₁ , ₁₃₁ , and ₁₄₁ . When the curvature radii R ₁₂₁ , R ₁₃₁ , and R ₁₄₁ are smaller than the above numerical range, the effect of the concave curved surfaces 121 c, 131 c, and 141 c to reduce the breakage of the negative electrode current collector is reduced. If the curvature radii R ₁₂₁ , R ₁₃₁ , and R ₁₄₁ are larger than the above numerical range, poor welding is likely to occur.

  As shown in FIGS. 13B, 15B, and 16B, the contour lines 121, 131, and 141 of the chamfered protrusions 120 ′, 130 ′, and 140 ′ are formed on the flat surface of the processing surface 11 and the concave curved surfaces 121c, 131c, and 141c. It is defined by the connection position. The outer dimension A of the chamfered protrusions 120 ′, 130 ′, 140 ′ is defined using the contour lines 121, 131, 141 defined in this way.

  Replacing part or all of the chamfering protrusions 120, 130, and 140 described in the first to fourth embodiments with the chamfering protrusions 120 ′, 130 ′, and 140 ′ of the fifth embodiment including the concave curved surfaces 121c, 131c, and 141c. Can do.

(Embodiment 6)
As shown in FIG. 2A, the processing surface 11 of the chip 10 has a substantially rectangular shape in plan view, and the processing surface 11 is adjacent to the four side surfaces 12a, 12b, 12c, and 12d. Preferably, the side surfaces 12a, 12b, 12c, and 12d are substantially perpendicular to the processed surface 11. 17A is a cross-sectional view of the chip 10 taken along line 17A-17A in FIG. 2A, and FIG. 17B is a cross-sectional view of the chip 10 taken along line 17B-17B in FIG. 2A. In FIGS. 17A and 17B, the projections 110 and 120 that should be visible behind the cross section are not shown in order to simplify the drawing. 17C is an enlarged plan view of the portion 17C of FIG. 2A including the corner portion of the processed surface 11. FIG.

  As shown in FIGS. 17A and 17B, chamfers 13 a, 13 b, 13 c, and 13 d are applied to the outer peripheral ends of the processed surface 11 where the processed surface 11 and the side surfaces 12 a, 12 b, 12 c, and 12 d intersect. Yes. The shapes of the chamfers 13a, 13b, 13c, and 13d are inclined planes (so-called “so-called“ R surfaces ”) that are obliquely intersected with any of the substantially cylindrical surface (so-called“ R surface ”), the processed surface 11, and the side surfaces 12a, 12b, 12c, and 12d. Although it can be arbitrarily selected from known chamfered shapes such as “C surface”), it is preferably a convex curved surface that smoothly connects the processed surface 11 and the side surfaces 12a, 12b, 12c, and 12d, and is an R surface. Is more preferable.

  As shown in FIG. 17C, chamfering 14 is also given to the corner portion of the processed surface 11 of the chip 10. In FIG. 17C, only one of the four corner portions of the processed surface 11 is illustrated, but the same chamfer 14 is also applied to the other three corner portions. The shape of the chamfer 14 is a well-known chamfered shape such as a substantially cylindrical surface (so-called “R surface”) and an inclined plane (so-called “C surface”) that obliquely intersects any of two adjacent side surfaces sandwiching the corner portion. Can be arbitrarily selected from the above, but is preferably a convex curved surface that smoothly connects two adjacent side surfaces, and more preferably an R surface.

  The processed surface 11 of the chip 10 is pressed against the negative electrode current collector 65n as shown in FIG. At this time, the processed surface 11 is in contact with the uppermost negative electrode current collector 65n. When chamfers 13 a, 13 b, 13 c, 13 d, and 14 are not provided around the processed surface 11 of the chip 10, the negative electrode current collector 65 n is locally pressed at the outer peripheral edge or corner portion of the processed surface 11. Therefore, it is difficult for the uppermost negative electrode current collector 65n to move with respect to the processed surface 11 particularly in the locally pressed position. In this state, when the protrusion formed on the processed surface 11 is pushed into the negative electrode current collector 65n, the negative electrode current collector 65n is greatly extended, so that the tear 930 (see FIG. 23) is likely to occur.

  On the other hand, when chamfers 13a, 13b, 13c, 13d, and 14 are provided around the machining surface 11 as in the sixth embodiment, the outer peripheral edge and corner portion of the machining surface 11 are negative electrode current collectors. Since the local pressing force applied to the body 65n is reduced, the action of restricting the movement of the uppermost negative electrode current collector 65n with respect to the processed surface 11 is particularly relaxed. Accordingly, when the protrusion formed on the processed surface 11 is pushed into the negative electrode current collector 65n, the negative electrode current collector 65n can be displaced with respect to the processed surface 11, so that it is broken 930 (see FIG. 23). Can be further reduced.

In this example, cylindrical chamfering with a radius R ₁₃ is performed as the chamfers ₁₃ a, 13 b, 13 c, and 13 d, and cylindrical chamfering with a radius R ₁₄ is performed as the chamfering 14. The radii R ₁₃ and R ₁₄ are preferably 0.5 mm or more, more preferably 0.7 mm or more, and preferably 2 mm or less, more preferably 1.5 mm or less. If the radii R ₁₃ and R ₁₄ are smaller than the above numerical range, it is difficult to obtain the effect of reducing the occurrence of the tear 930 (see FIG. 23). If the radii R ₁₃ and R ₁₄ are larger than the above numerical range, the time required for the chamfering process becomes long.

  It is preferable that a chamfer formed by intersecting a chamfer 14 between two adjacent side surfaces and a chamfer formed at the outer peripheral end of the processed surface 11 is formed at the top of each corner portion of the processed surface 11. . The chamfer at the top is preferably a smooth convex curved surface, more preferably a substantially spherical surface. The chamfer at the top is particularly preferably a spherical surface having a radius of 0.5 mm or more, further 0.7 mm or more, 2 mm or less, and further 1.5 mm or less.

  All or only a part of the chamfers 13a, 13b, 13c, 13d, and 14 described in the fifth embodiment can be applied to the chip 10 described in the first to fifth embodiments.

  In the present invention, the processing method of the chamfered protrusions 120, 130, 140, 120 ', 130', 140 'is not particularly limited. For example, after forming the non-chamfered protrusion 110 on the processed surface 11 of the chip 10 by a known method, the chamfered protrusion 120, 130, 140, 120 ′, 130 ′, 140 ′ is formed by chamfering using a file or the like. Can be formed.

  In said Embodiment 1-6, although several protrusion was arrange | positioned on the processing surface 11 at the grid | lattice form, this invention is not limited to this. For example, a plurality of protrusions may be arranged in a honeycomb shape.

  In the first to sixth embodiments, the vertical and horizontal dimensions of the protrusions 110, 120, 130, 140, 120 ′, 130 ′, and 140 ′ when the processed surface 11 is viewed from the front are all A. The vertical dimension and the horizontal dimension may be different. The planar view shape of the protrusion may be an arbitrary shape such as a substantially rectangular shape, a substantially regular hexagonal shape in addition to a substantially square shape. The outer dimension A of the contour line around the protrusion is defined by the outer dimension along the direction in which the outer dimension of the contour line is minimized. For example, when the planar view shape of the projection is substantially rectangular, the outer dimension A means the dimension in the short side direction, and when the planar view shape of the projection is substantially regular hexagon, the outer dimension A is It means the distance between two opposite sides.

  In the first to sixth embodiments described above, the case where the negative electrode welded portion 64n is formed by the tip 10 of the present invention has been described. However, the positive electrode welded portion 64p can also be formed, and in this case, the same effect as described above can be obtained.

(Embodiment 7)
The ultrasonic welding machine 1 provided with the chip 10 of the present invention shown in the first to sixth embodiments can be preferably used for welding foil-like materials. Among them, the battery, particularly the laminated lithium ion shown in FIG. It can be used for welding the electrode tab of the secondary battery 60 and the lead tab.

  The general configuration of the lithium ion secondary battery 60 will be outlined below.

  The positive electrode 61p has a structure in which, for example, a layer (positive electrode mixture layer) 66p made of a positive electrode mixture containing a positive electrode active material, a conductive additive, a binder, and the like is formed on one surface or both surfaces of the current collector 65p.

A positive electrode active material consists of an active material which can occlude / release lithium ion. Such a positive electrode active material includes, for example, lithium having a layered structure represented by Li _{1 + x} MO ₂ (−0.1 <x <0.1, M: Co, Ni, Mn, Al, Mg, etc.) Transition metal oxide, LiMn ₂ O ₄ , lithium manganese oxide having a spinel structure in which part of the element is replaced with another element, and olivine type represented by LiMPO ₄ (M: Co, Ni, Mn, Fe, etc.) It preferably consists of any one of compounds.

Lithium-containing transition metal oxide of the above layered structure, for _{example, LiCoO 2, LiNi 1-x} Co xy Al y O 2 (0.1 ≦ x ≦ 0.3,0.01 ≦ y ≦ 0.2), And an oxide containing at least Co, Ni and Mn (LiMn _1/3 Ni _1/3 Co _1/3 O ₂ , LiMn _5/12 Ni _5/12 Co _1/6 O ₂ , LiNi _3/5 Mn _1/5 Co _1/5 O ₂ or LiNi _0.5 Co _0.2 Mn _0.3 ) is preferable.

  The current collector 65p of the positive electrode 61p is preferably made of, for example, an aluminum foil or an aluminum alloy foil. The thickness of the current collector 65p varies depending on the size and capacity of the battery, but is preferably 0.01 to 0.02 mm, for example.

  The positive electrode 61p is manufactured by the following method. A positive electrode mixture containing the above-described positive electrode active material, a conductive additive such as graphite, acetylene black, carbon black, and fibrous carbon, and a binder such as polyvinylidene fluoride (PVDF) is used as N-methyl-2-pyrrolidone. A paste-like or slurry-like composition uniformly dispersed using a solvent such as (NMP) is prepared (the binder may be dissolved in the solvent). This composition is intermittently applied onto a strip-shaped current collector and dried. You may adjust the thickness of a positive mix layer by press processing as needed. The long positive electrode substrate (electrode substrate) thus obtained is cut into a predetermined shape using, for example, a Thomson blade to obtain the positive electrode 61p.

  The thickness of the positive electrode mixture layer 66p in the positive electrode 61p is preferably 30 to 100 μm per side. Moreover, it is preferable that content of each structural component in the positive mix layer 66p is positive electrode active material: 90-98 mass%, conductive support agent: 1-5 mass%, binder: 1-5 mass%.

  The positive electrode lead tab 63p is preferably made of aluminum or an aluminum alloy. The thickness of the positive electrode lead tab 63p is preferably 20 to 300 μm.

  In FIG. 19, the positive electrode lead tab 63 p is led out to the outside of the outer package 68, but a positive electrode terminal of a different member is connected to the positive electrode lead tab 63 p and the positive electrode terminal is led out of the outer package 68. Also good. The material of such a positive electrode terminal is determined from the viewpoint of facilitating connection with a device that uses the battery 60. For example, aluminum or an aluminum alloy can be used. Moreover, it is preferable that the thickness of a positive electrode terminal is 50-300 micrometers.

  As a method for connecting the ear 62p of the positive electrode 61p and the positive lead tab 63p, ultrasonic welding using the tip 10 of the present invention can be used. In addition to ultrasonic welding, various methods such as resistance welding, laser welding, caulking, and adhesion using a conductive adhesive can also be used.

  The negative electrode 61n has, for example, a structure in which a layer (negative electrode mixture layer) 66n containing a negative electrode active material capable of inserting and extracting lithium ions is formed on one side or both sides of the current collector 65n.

  Negative electrode active materials include graphite, pyrolytic carbons, cokes, glassy carbons, fired organic polymer compounds, mesocarbon microbeads (MCMB), and carbon that can occlude and release lithium ions such as carbon fibers. It is preferable that it consists of 1 type, or 2 or more types of mixtures of type | system | group material.

Alternatively, the negative electrode active material may be an element such as Si, Sn, Ge, Bi, Sb, or In, an alloy of Si, Sn, Ge, Bi, Sb, or In, a lithium-containing nitride, or a lithium metal such as lithium oxide. It is preferably made of any one of a compound (LiTi ₃ O ₁₂ or the like) that can be charged and discharged at a near low voltage, lithium metal, and a lithium / aluminum alloy.

  A copper foil is suitable as the current collector 65n of the negative electrode 61n. Copper foils are roughly classified into electrolytic copper foils and rolled copper foils depending on the manufacturing method. Electrolytic copper foil is relatively inexpensive. The thickness of the current collector 65n varies depending on the size or capacity of the battery, but is preferably 0.005 to 0.02 mm, for example.

  The negative electrode 61n is produced by the following method. The negative electrode active material described above, a binder (such as a mixed binder of rubber binder such as PVDF or styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC)), and graphite, acetylene black, carbon black, etc. A paste-like or slurry-like composition in which a negative electrode mixture containing a conductive aid or the like is uniformly dispersed using a solvent such as NMP or water is prepared (the binder may be dissolved in the solvent). . This composition is intermittently applied onto a strip-shaped current collector and dried. You may adjust the thickness or density of a negative mix layer by press processing as needed. The long negative electrode substrate (electrode substrate) thus obtained is cut into a predetermined shape using, for example, a Thomson blade to obtain a negative electrode 61n.

  The thickness of the negative electrode mixture layer 66n in the negative electrode 61n is preferably 30 to 100 μm per side. Moreover, it is preferable that content of each structural component in the negative mix layer 66n is negative electrode active material: 90-98 mass%, binder: 1-5 mass%. Moreover, when using a conductive support agent, it is preferable that content of the conductive support agent in 66 n of negative mix layers is 1-5 mass%.

  The negative electrode lead tab 63n is preferably made of copper. If necessary, nickel plating or the like may be applied to the surface. The thickness of the negative electrode lead tab 63n is preferably 20 to 300 μm.

  In FIG. 19, the negative electrode lead tab 63 n is led out to the outside of the outer package 68, but a negative electrode terminal of a different member is connected to the negative electrode lead tab 63 n and the negative electrode terminal is led out of the outer package 68. Also good. The material of such a negative electrode terminal is determined from the viewpoint of facilitating connection with a device that uses the battery 60. For example, nickel, nickel-plated copper, nickel-copper clad, or the like can be used. Moreover, it is preferable that the thickness of a negative electrode terminal is 50-300 micrometers similarly to a positive electrode terminal.

  As a method for connecting the ear portion 62n of the negative electrode 61n and the negative electrode lead tab 63n, ultrasonic welding using the tip 10 of the present invention can be used. As described above, since the chip 10 of the present invention can reduce the occurrence of breakage of the metal foil in contact with the chip 10, an electrolytic copper foil that is relatively inferior in elongation resistance is used as the negative electrode current collector 65n. However, it is possible to manufacture a battery in which the ear 62n made of the negative electrode current collector 65n is not broken. As a result, the cost of the battery can be reduced by using a relatively inexpensive electrolytic copper foil. In addition to the ultrasonic welding, various methods such as resistance welding, laser welding, caulking, adhesion with a conductive adhesive, and the like can be used as a method for connecting the ear 62n and the negative electrode lead tab 63n.

  The separator 66 includes a porous film that separates the positive electrode 61p and the negative electrode 61n and transmits lithium ions. The separator 66 preferably has a safety mechanism (shutdown characteristic) that melts and closes the hole when the battery 60 abnormally generates heat and reaches a high temperature (for example, 100 to 140 ° C.). From such a viewpoint, the porous film is preferably made of a thermoplastic resin having a melting point of about 80 to 140 ° C., and specifically, preferably made of a polyolefin polymer such as polypropylene or polyethylene. The thickness of the porous film is not particularly limited, but is preferably 10 to 50 μm.

  The separator 66 may be formed by coating a plate-like inorganic fine particle layer on the porous film. Thereby, the thermal contraction of the separator 66 at the time of abnormal heat generation can be suppressed, and safety can be improved.

  Alternatively, the separator 66 may have a laminated structure of the porous film and the heat resistant porous substrate. As the heat resistant porous substrate, for example, a fibrous material having a heat resistant temperature of 150 ° C. or higher can be used. The fibrous material may be formed of at least one material selected from the group consisting of cellulose and its modified products, polyolefin, polyethylene terephthalate, polybutylene terephthalate, polypropylene, polyester, polyacrylonitrile, aramid, polyamideimide, and polyimide. it can. Specifically, it is preferably made of a nonwoven fabric made of the above materials.

  “Heat resistance” of the porous substrate means that a substantial dimensional change due to softening or the like does not occur. Specifically, is the upper limit temperature (heat resistant temperature) at which the rate of shrinkage (shrinkage ratio) with respect to the length of the porous substrate at room temperature maintained at 5% or less is sufficiently higher than the shutdown temperature of the separator? The heat resistance is evaluated depending on whether or not. In order to increase the safety of the laminated battery after shutdown, it is desirable that the porous substrate has a heat resistance higher by 20 ° C. than the shutdown temperature. More specifically, the heat resistance temperature of the porous substrate is 150 ° C. It is preferable that the temperature is higher than or equal to ° C, and more preferably higher than or equal to 180 ° C.

As the electrolytic solution, for example, a solution (nonaqueous electrolytic solution) in which a solute such as LiPF ₆ or LiBF ₄ is dissolved in a high dielectric constant solvent or an organic solvent can be used. As the high dielectric constant solvent, any of ethylene carbonate (EC), propylene carbonate (PC), and γ-butyrolactone (BL) can be used. As the organic solvent, a low viscosity solvent such as linear dimethyl carbonate (DMC), diethyl carbonate (DEC), or methyl ethyl carbonate (EMC) can be used.

  As the solvent of the electrolytic solution, it is preferable to use a mixed solvent of the above-described high dielectric constant solvent and low viscosity solvent. Alternatively, PVDF, a rubber-based material, an alicyclic epoxy, a material having an oxetane-based three-dimensional crosslinked structure, and the like may be mixed and solidified into the above-described solution to form a polymer electrolyte.

  The separator 66 is interposed between the positive electrode 61p and the negative electrode 61n, and the positive electrode 61p and the negative electrode 61n are alternately stacked to form an electrode laminate 67.

  There is no restriction | limiting in particular in the production method of the electrode laminated body 67. FIG. For example, the band-shaped separator 66 is alternately zigzag-folded by alternately repeating mountain folds and valley folds at regular intervals, and the positive electrode 61p is sandwiched between the one surface side of the separator 66 and each valley fold portion, and the other surface side Thus, the electrode laminate 67 can be formed by sandwiching the negative electrode 61n in each valley folded portion. Alternatively, the electrode stack 67 may be formed by forming a plurality of rectangular bags with the separators 66 and inserting the positive electrodes 61p into the bags made of the separators 66 alternately with the negative electrodes 61n. .

  The positive electrode lead tab 63p is connected to the positive electrode ears 62p of the plurality of positive electrodes 61p protruding from the electrode laminate 67 thus obtained. Similarly, the negative electrode lead tab 63n is connected to the negative electrode ears 62n of the plurality of negative electrodes 61n protruding from the electrode laminate 67.

  Two laminate sheets 69 having a substantially rectangular shape are arranged above and below the electrode laminate 67 thus obtained, and two laminate sheets are disposed along three sides excluding the side where the positive electrode lead tab 63p and the negative electrode lead tab 63n are formed. 69 is heat-sealed to form a laminate sheet 69 into a bag shape. Rather than using two laminate sheets, one rectangular laminate sheet is folded and stacked so as to sandwich the electrode laminate 67, and heat-sealed along two opposing sides to form a laminate sheet in a bag shape It may be formed. Thereafter, an electrolytic solution is injected into the bag of the laminate sheet 69. Finally, the laminate sheet 69 is heat-sealed together with the positive and negative lead tabs 63p and 63n along the side that is not heat-sealed, whereby the lithium ion secondary battery 60 is obtained.

  There is no restriction | limiting in particular in the structure of the laminate sheet 69, For example, the well-known laminate sheet currently used as an exterior material of a laminate-type lithium ion secondary battery can be used. For example, a multilayer sheet in which a modified polyolefin layer is laminated as a heat-fusible resin layer on one side of a base layer made of aluminum can be used.

  In the above example, the positive electrode lead tab 63p and the negative electrode lead tab 63n are drawn from the same short side of the substantially rectangular laminate sheet 69, but may be drawn from different sides.

  Although the example of the laminated lithium ion secondary battery has been described above, the chip 10 of the present invention can also be used for manufacturing a lithium ion secondary battery other than the laminated type.

(Evaluation Test 1)
An electrode laminate 67 (see FIG. 19) for the laminated lithium ion secondary battery 60 was produced as follows.

  As the positive electrode current collector 65p, an aluminum foil having a thickness of 15 μm was used. A positive electrode mixture layer 66p having a thickness of 110 μm was applied and formed in predetermined regions on both surfaces of the current collector 65p to obtain a positive electrode 61p.

  An electrolytic copper foil having a thickness of 10 μm was used as the negative electrode current collector 65n. A negative electrode mixture layer 66n having a thickness of 126 μm was applied and formed in a predetermined region on both surfaces of the current collector 65n to obtain a negative electrode 61n.

  A strip-shaped separator 66 made of a porous film and having a thickness of 21 μm is folded in a zigzag shape, and the positive electrode 61p is sandwiched from one side of the separator 66 to each valley fold, and the above-mentioned each valley fold from the other side. The negative electrode electrode 61n was sandwiched, so that an electrode laminate 67 in which 22 positive electrodes 61p and 23 negative electrodes 61n were alternately laminated via separators 66 was obtained.

  As shown in FIG. 21, the ears 62n of the 23 negative electrodes 61n protruding from one side of the electrode laminate 67 are superimposed on a lead tab 63n (20 mm width Cu—Ni) having a thickness of 285 μm and a width of 20 mm, Both were joined by ultrasonic welding. The lead tab 63n is obtained by performing nickel plating on both surfaces of a copper thin plate.

In the embodiment, the chip 10 having the processing surface 11 in which 16 chamfering protrusions 130 ′ having convex curved surfaces swelled in a dome shape shown in FIG. 15A are arranged in a grid in 2 rows × 8 columns is used. Then, ultrasonic welding was performed. The diameter A (see FIG. 10A) of the circular outline 131 of the protrusion 130 ′ when the processed surface 11 was viewed in plan was 0.6 mm. The height of the protrusion 130 ′ was 0.3 mm. A concave curved surface 131c (see FIG. 15B) continuously formed in an annular shape around the protrusion 130 ′ along the contour line 131 had an arc-shaped cross section with a curvature radius R ₁₃₁ of 0.2 mm. Cylindrical chamfers 13 a, 13 b, 13 c, and 13 d (see FIGS. 17A and 17B) having a radius R ₁₃ of 1 mm are applied to the outer peripheral end of the processing surface 11 of the chip 10. The part had a cylindrical chamfer 14 (see FIG. 17C) with a radius R ₁₄ of 1 mm. The processed surface 11 on which such a protrusion 130 ′ was formed was pressed against the current collector 65 n constituting the ear portion 62 n and ultrasonically welded. Ten electrode laminates 67 were ultrasonically welded to the lead tabs 63n.

In the comparative example, ultrasonic welding was performed under the same conditions as in the example except that the tip 10 different from that in the example was used. On the processed surface 11 of the chip 10 used in the comparative example, the 16 non-chamfered projections 110 shown in FIGS. 3A and 3B were arranged in a grid of 2 rows × 8 columns. The outline 111 of the non-chamfered protrusion 110 when the processed surface 11 is viewed in plan is a square having a side length A of 1.2 mm, and the outline 113 of the upper surface 112 is a square having a side length of 0.6 mm. . The height of the protrusion 110 was 0.3 mm. The arrangement pitch of the protrusions 110 in the vertical and horizontal directions was the same as that of the protrusion 130 ′ of the chip 10 of the example. The concave curved surface 121c (see FIG. 13B) was not formed on the contour line 111 around the protrusion 110 (that is, the curvature radius R ₁₂₁ <0.05 mm). Chamfers 13a, 13b, 13c, and 13d (see FIGS. 17A and 17B) of the outer peripheral edge of the machining surface 11 and chamfers 14 at four corners of the machining surface 11 (see FIG. 17C) formed in the chip 10 of the example. Were not applied in the comparative examples (that is, R ₁₃ <0.1 mm, R ₁₄ <0.1 mm). Using the chip 10 of the above comparative example, ultrasonic welding of the 10 electrode laminates 67 to the lead tabs 63n was performed in the same manner as in the example.

  For each of the ten samples of the example and the comparative example, each ultrasonic weld 64n was observed with a digital microscope, and it was determined whether or not the current collector 65n constituting the ear 62n was broken.

  As a result, in the example, the current collector 65n was not broken in any of the ten samples. On the other hand, in the comparative example, the uppermost current collector 65n was broken in all of the ten samples. From this, it was confirmed that the chip 10 used in the example is effective in preventing the current collector from being broken.

(Evaluation test 2)
The same 23 negative electrode current collectors 65n used in the evaluation test 1 in which the negative electrode mixture layer 66n was not formed were prepared. The ears 62n of the 23 negative electrode current collectors 65n were superposed on the same lead tab 63n as in the evaluation test 1, and these were joined by ultrasonic welding. The conditions for ultrasonic welding were the same as those in Evaluation Test 1. Ten samples were obtained for each of the examples and comparative examples.

  For each sample, a tensile test was performed on the uppermost negative electrode current collector 65n on which the chip 10 was pressed. That is, with the lead tab 63n held, a gradually increasing tension was applied to the uppermost negative electrode current collector 65n, and the tension at the time when the negative electrode current collector 65n was broken was measured. The strength (unit: N / 10 mm) of the negative electrode current collector was determined by converting the tension (unit: N) into a tension per 10 mm width of the ear 62n.

  The results are shown in FIG. The upper graph of FIG. 18 shows the intensity | strength of the negative electrode electrical power collector of each 10 samples of an Example and a comparative example. Below FIG. 18, the average value, maximum value, minimum value, and standard deviation of the intensity for each of the ten samples of the example and the comparative example are shown. From FIG. 18, it was confirmed that the chip 10 used in the example is effective in preventing the current collector from being broken since the degree of reducing the tensile strength of the current collector is small.

  The battery manufacturing method of the present invention can be preferably used for manufacturing a secondary battery in which sheet-like positive electrodes and sheet-like negative electrodes are alternately arranged via separators.

  The tip for ultrasonic welding and the ultrasonic welder of the present invention can be preferably used in a step of ultrasonic welding by pressing a tip against a foil-like member to be welded. In particular, it can be particularly preferably used in the step of ultrasonic welding the current collector and the lead tab constituting the electrode of the secondary battery.

DESCRIPTION OF SYMBOLS 1 Ultrasonic welding machine 5 Horn 10 Tip 11 Processing surface 13a, 13b, 13c, 13d Chamfering 14 Chamfering 50 Anvil 60 Laminate type lithium ion secondary battery 62p, 62n Ear part 63p, 63n Lead tab 65p, 65n Current collector 66p, 66n Electrode mixture layer 120, 130, 140, 120 ', 130', 140 'Chamfering protrusion 121, 131, 141 Contour line 121c, 131c, 141c Concave surface 121r Arc

  The present invention relates to a tip for ultrasonic welding that is pressed against a member to be welded (so-called “workpiece”) and ultrasonically welds the member to be welded by applying ultrasonic vibration to the member to be welded. Moreover, this invention relates to the ultrasonic welding machine provided with the said chip | tip. Furthermore, this invention relates to the manufacturing method of the battery which has the process of performing ultrasonic welding using the said chip | tip.

  A non-aqueous electrolyte battery represented by a lithium ion secondary battery is widely used as a power source for portable devices such as a mobile phone and a notebook personal computer because of its high energy density. With higher performance of portable devices, further increase in capacity of lithium ion secondary batteries is being promoted. In order to further improve the energy density, a laminated lithium ion sheathed with a flexible laminate sheet in which a metal foil such as an aluminum foil is used as a core material and a heat-fusible resin film is laminated as an adhesive layer on its inner surface Secondary batteries are often used.

  As an electrode laminated body incorporated in a laminated lithium ion secondary battery, a sheet-like positive electrode and a sheet-like negative electrode are alternately laminated via a separator in general.

  FIG. 19 is a perspective plan view showing a schematic configuration of a general laminate-type lithium ion secondary battery 60. In FIG. 19, 61p is a positive electrode and 61n is a negative electrode. The positive and negative electrodes 61p and 61n each have a current collector made of metal foil as a base material layer. The substantially rectangular electrode portions 71p and 71n and the ear portions 62p protruding from one side of the electrode portions 71p and 71n. , 62n. In the electrode portions 71p and 71n, an electrode mixture layer containing an active material is applied and formed on both surfaces of the current collector, while no electrode mixture layer is applied and formed on the ear portions 62p and 62n. The positive electrode 61p and the negative electrode 61n are alternately stacked via the separator 66 to constitute an electrode stacked body 67. The ears 62p of the plurality of positive electrodes 61p are overlapped with each other and welded by lead tabs 63p and welds 64p. Similarly, the ears 62n of the plurality of negative electrodes 61n are overlapped with each other and welded by lead tabs 63n and welds 64n. In FIG. 19, 68 is an exterior housing the electrode laminate 67. The exterior 68 is composed of two laminate sheets (exterior materials) 69 having flexibility. The two laminate sheets 69 are heat-sealed and sealed by a heat seal part 69a along the outer peripheral edge.

  FIG. 20 is a cross-sectional view along the thickness direction showing a schematic configuration of the negative electrode weld 64n and the vicinity thereof. In FIG. 20, the illustration of the separator 66 and the laminate sheet 69 between the positive electrode 61p and the negative electrode 61n is omitted to simplify the drawing. In FIG. 20, 65p is a positive electrode current collector, 66p is a positive electrode mixture layer applied to both surfaces of the positive electrode current collector 65p, 65n is a negative electrode current collector, and 66n is applied to both surfaces of the negative electrode current collector 65n. Negative electrode mixture layer. A plurality of negative electrode current collectors 65n constituting the negative electrode ear portion 62n are superimposed on the negative electrode lead tab 63n, and these are integrally welded at the welding portion 64n. Although not shown, the configuration of the positive electrode weld 64p is substantially the same as that shown in FIG. 20 (see, for example, Patent Document 1).

  As the positive electrode current collector 65p, an aluminum foil with a thickness of about 15 μm is generally used, and as the positive electrode lead tab 63p, an aluminum thin plate with a thickness of about 200 μm is used. On the other hand, a copper foil having a thickness of about 10 μm is generally used as the negative electrode current collector 65n, and a nickel-plated copper thin plate having a thickness of about 200 μm is used as the negative electrode lead tab 63n.

  In general, ultrasonic welding is used to weld the current collectors 65p, 65n constituting the ears 62p, 62n and the lead tabs 63p, 63n at the welds 64p, 64n.

  The ultrasonic welding method will be described with reference to FIG. Although FIG. 21 shows a case where the negative electrode weld 64n is formed, the positive electrode weld 64p is substantially the same.

  As shown in FIG. 21, a plurality of negative electrode current collectors 65n constituting lead tabs 63n and ears 62n are sequentially stacked on the upper surface 51 of the anvil 50, and the chip 10 is placed on the negative electrode current collector 65n. While pressing the chip 10 against the negative electrode current collector 65n with the load F so as to compress the lead tab 63n and the negative electrode current collector 65n between the chip 10 and the anvil 50, the vibration is generated in a direction orthogonal to the direction of the load F. A sonic vibration S is applied to the chip 10. The ultrasonic vibration applied through the chip 10 heats the interfaces of the plurality of negative electrode current collectors 65n and the lead tabs 63n with frictional heat, thereby forming welds 64n (see FIGS. 19 and 20).

  A surface (hereinafter referred to as “processed surface”) 11 of the tip 10 that abuts against the negative electrode current collector 65n so that the energy of ultrasonic vibration is efficiently applied to the negative electrode current collector 65n and the lead tab 63n that are welded members. The surface 51 (hereinafter referred to as “holding surface”) 51 that contacts the lead tab 63n of the anvil 50 is formed with fine irregularities of a predetermined shape.

  22A is a plan view showing an example of the shape of the processed surface 11 of the chip 10, and FIG. 22B is a front view thereof. As shown in these drawings, a plurality of projections 910 having a quadrangular pyramid shape (a shape obtained by cutting off the top of the quadrangular pyramid along a plane parallel to the bottom surface) are vertically and horizontally formed on the processed surface 11. It is arranged in a grid in the direction. The plurality of protrusions 910 have the same shape and dimensions.

JP 2007-26945 A

  When the processed surface 11 of the chip 10 shown in FIGS. 22A and 22B is pressed against the negative electrode current collector 65n as shown in FIG. 21 to perform ultrasonic welding, depending on the ultrasonic welding conditions, the welded portion 64n or There may be a problem in that the negative electrode current collector 65n (particularly, the uppermost negative electrode current collector 65n with which the processed surface 11 abuts) is broken in the vicinity thereof. This will be described with reference to FIG.

  FIG. 23 is an enlarged plan view showing an example of a welded portion 64n formed by ultrasonic welding using the chip 10 having the processed surface 11 shown in FIGS. 22A and 22B. The processed surface 11 was in contact with the surface of the welded portion 64n shown in FIG. As shown in FIG. 23, a projection 910 (FIGS. 22A and 22B) on the processed surface 11 is formed on the uppermost negative electrode current collector 65n (hereinafter referred to as “the uppermost negative electrode current collector 65n”). The welding mark 920 which is a substantially quadrangular frustum-shaped concave portion is formed by being pressed.

  930 is a tear generated in the uppermost negative electrode current collector 65n by ultrasonic welding. The tear 930 is likely to occur in the vicinity of the welding marks 920 arranged at the peripheral portion, particularly at the four corners, among the plurality of welding marks 920 arranged in a lattice shape.

  As can be understood from FIG. 21, the ear portion 62n is thinner than the electrode portion because the mixture layer 66n is not formed. Since the plurality of negative electrode current collectors 65n constituting such thin ear portions 62n are bundled in the thickness direction between the chip 10 and the lead tab 63n, tension is easily applied to the negative electrode current collector 65n. . By pressing the protrusion 910 of the processed surface 11 against such a negative electrode current collector 65n, particularly the uppermost negative electrode current collector 65n is locally extended along the shape of the protrusion 910. Therefore, in the uppermost negative electrode current collector 65n, it is considered that the tear 930 is likely to occur at a position in the vicinity of the welding mark 920 in the peripheral portion where the largest tension is easily applied among the plurality of welding marks 920.

  In addition, although the unevenness | corrugation is formed also in the holding surface 51 of the anvil 50, since the lead tab 63n with which the holding surface 51 contacts is thicker than the negative electrode current collector 65n, the lead tab 63n is hardly broken.

  If the load F (see FIG. 21) of the chip 10 is reduced, the frequency of occurrence of the tear 930 is reduced, but the energy of ultrasonic vibration is not sufficiently applied to the negative electrode current collector 65n and the lead tab 63n. Prone to occur.

  Therefore, in order to suppress the generation of the break 930, conventionally, (1) a rolled copper foil having relatively excellent elongation resistance is used as the copper foil constituting the negative electrode current collector 65n. A “dummy thin plate / a plurality of negative electrode current collectors 65n / lead tabs 63n” is integrally ultrasonically welded with a copper dummy thin plate having substantially the same thickness as the lead tab 63n interposed between the negative electrode current collector 65n and the negative tab current collector 65n. Measures have been taken, such as making it difficult to form weld marks 920 on the uppermost negative electrode current collector 65n.

  However, the method using a rolled copper foil has a problem that the rolled copper foil is more expensive than the electrolytic copper foil. In addition, the method of welding the dummy thin plates together has a problem that the dummy thin plate needs to be prepared, and thus there is a problem that the cost is high, a problem that the ultrasonic welding work is complicated, and a problem that the welded portion 64n is thick. .

  The above-mentioned problem that the current collector is broken by ultrasonic welding is likely to occur in the negative electrode current collector having a relatively thin thickness, but the same applies to the positive electrode current collector depending on the ultrasonic welding conditions. May occur. Also, in fields other than batteries, the same phenomenon may occur when the chip 10 is pressed against a thin metal foil and ultrasonic welding is performed.

  The breakage of the current collector may adversely affect the voltage characteristics of the finally obtained lithium ion secondary battery. Therefore, tearing reduces the manufacturing yield of the battery and also reduces the reliability of the battery.

  An object of the present invention is to provide an ultrasonic welding tip and an ultrasonic welding machine in which a foil that is a member to be welded hardly breaks. Another object of the present invention is to provide a battery manufacturing method in which the current collectors constituting the ears are less likely to be broken when the electrode ears and the lead tabs are ultrasonically welded.

  The tip for ultrasonic welding of the present invention has a processed surface on which a plurality of protrusions are formed, and applies ultrasonic vibration to the member to be welded while pressing the processed surface against the member to be welded. An ultrasonic welding tip for ultrasonic welding, when the processed surface is viewed from the front, at least one of the plurality of protrusions arranged on the outermost periphery has an outer dimension in one direction. It is a chamfering protrusion chamfered so as to have an arc having a radius R satisfying R ≧ A / 6 on the surrounding contour line when A.

  An ultrasonic welding machine of the present invention includes a tip that is pressed against a member to be welded to apply ultrasonic vibrations to the member to be welded, and an anvil that is disposed to face the tip and supports the member to be welded. And a horn that is provided at one end and resonates by the ultrasonic vibration. And the said chip | tip is a chip | tip for ultrasonic welding of said this invention.

  The battery manufacturing method of the present invention has a current collector as a base material layer, an electrode portion in which an electrode mixture layer is formed in a predetermined region of the current collector, and the electrode mixture layer is not formed A step of laminating a plurality of electrodes each having an ear portion, and a step of ultrasonically welding the ear portion of the plurality of electrodes and a lead tab thicker than the current collector. Then, in the ultrasonic welding step, the processed surface of the ultrasonic welding tip of the present invention is pressed against the ear portion to ultrasonically weld the ear portion and the lead tab.

  According to the ultrasonic welding tip and the ultrasonic welding machine of the present invention, since at least one projection arranged on the outermost periphery among the plurality of projections formed on the processing surface of the tip is a chamfering projection, stress is applied to the foil. Concentration hardly occurs. Therefore, the tearing of the foil by ultrasonic welding can be reduced.

  Further, according to the battery manufacturing method of the present invention, the above-described ultrasonic welding tip of the present invention is pressed against the ear portion of the electrode to weld the electrode ear portion and the lead tab. The tear which arises in the electrical power collector which comprises can be reduced. Therefore, a highly reliable battery can be stably manufactured with a high yield. Moreover, it becomes possible to use the electrolytic copper foil which was difficult to use conventionally as a collector. Further, it is not necessary to perform ultrasonic welding with a dummy thin plate sandwiched between the tip and the ear.

FIG. 1 is a diagram showing a schematic configuration of an example of an ultrasonic welder according to the present invention. FIG. 2A is a plan view of a processed surface of a tip according to Embodiment 1 of the present invention used in an ultrasonic welding machine, and FIG. 2B is a front view thereof. FIG. 3A is an enlarged plan view of non-chamfered protrusions arranged at the corners other than the four corners among the plurality of protrusions formed on the processed surface of the chip shown in FIGS. 2A and 2B, and FIG. 3B is a line 3B-3B in FIG. 3A. It is an arrow expanded sectional view of the non-beveling protrusion along. 4A is an enlarged plan view of chamfered protrusions arranged at four corners among the plurality of protrusions formed on the processed surface of the chip shown in FIGS. 2A and 2B, and FIG. 4B is along the line 4B-4B in FIG. 4A. It is an arrow expanded sectional view of a chamfering protrusion. FIG. 5 is an enlarged plan view showing a weld portion formed by ultrasonic welding using the tip shown in FIGS. 2A and 2B. FIG. 6 is a plan view showing an arrangement of a plurality of protrusions formed on the processing surface of another tip used in the ultrasonic welding machine according to the first embodiment of the present invention. FIG. 7 is a plan view showing an arrangement of a plurality of protrusions formed on the processing surface of the tip used in the ultrasonic welding machine according to the second embodiment of the present invention. FIG. 8 is a plan view showing an arrangement of a plurality of protrusions formed on the processing surface of the tip used in the ultrasonic welding machine according to the third embodiment of the present invention. FIG. 9A is a plan view of a processed surface of a tip according to Embodiment 4 of the present invention used in an ultrasonic welding machine, and FIG. 9B is a front view thereof. 10A is an enlarged plan view of chamfered protrusions arranged at four corners among the plurality of protrusions formed on the processed surface of the chip shown in FIGS. 9A and 9B, and FIG. 10B is along the line 10B-10B in FIG. 10A. It is an arrow expanded sectional view of a chamfering protrusion. FIG. 11 is an enlarged plan view showing a welded portion formed by ultrasonic welding using the tip shown in FIGS. 9A and 9B. 12A is an enlarged plan view of another chamfering protrusion formed on the processing surface of the tip used in the ultrasonic welding machine according to Embodiment 4 of the present invention, and FIG. 12B is a chamfering protrusion along the line 12B-12B in FIG. 12A. FIG. FIG. 13A is a cross-sectional view of a chamfered protrusion formed on a processed surface of a tip used in an ultrasonic welder according to Embodiment 5 of the present invention. FIG. 13B is an enlarged cross-sectional view of the portion 13B of FIG. 13A. FIG. 14A is a plan view of a welding mark formed by the chamfered protrusion shown in FIGS. 13A and 13B. 14B is a cross-sectional view of the weld mark taken along the line 14B-14B in FIG. 14A. FIG. 14C is an enlarged cross-sectional view of the portion 14C of FIG. 14B. FIG. 15A is a cross-sectional view of another chamfering protrusion formed on the processed surface of the tip used in the ultrasonic welding machine according to the fifth embodiment of the present invention. FIG. 15B is an enlarged cross-sectional view of the portion 15B of FIG. 15A. FIG. 16A is a cross-sectional view of still another chamfering protrusion formed on the processing surface of the tip used in the ultrasonic welding machine according to the fifth embodiment of the present invention. FIG. 16B is an enlarged cross-sectional view of the portion 16B of FIG. 16A. 17A is a cross-sectional view of the chip taken along the line 17A-17A in FIG. 2A. FIG. 17B is a cross-sectional view of the chip taken along the line 17B-17B in FIG. 2A. FIG. 17C is an enlarged plan view of a portion 17C of FIG. 2A. FIG. 18 is a diagram showing the results of Examples and Comparative Examples in Evaluation Test 2. FIG. 19 is a perspective plan view showing a schematic configuration of a general laminated lithium ion secondary battery. FIG. 20 is a cross-sectional view showing a schematic configuration of a welded portion between the ear portion of the negative electrode and the REIT tab and the vicinity thereof in the laminated lithium ion secondary battery shown in FIG. FIG. 21 is a side view showing an ultrasonic welding method for forming the weld shown in FIG. FIG. 22A is a plan view showing an example of the shape of a processed surface of a conventional tip used for ultrasonic welding, and FIG. 22B is a front view thereof. FIG. 23 is an enlarged plan view showing an example of a welded portion formed by ultrasonic welding using a chip having the processed surface shown in FIGS. 22A and 22B.

  The ultrasonic welding tip of the present invention includes a processed surface on which a plurality of protrusions are formed. The tip is used for applying ultrasonic vibration to the member to be welded while pressing the processed surface against the member to be welded to ultrasonically weld the member to be welded. When the processed surface is viewed from the front, at least one protrusion arranged on the outermost periphery among the plurality of protrusions is an arc having a radius R that satisfies R ≧ A / 6 when the outer dimension in one direction is A. Is a chamfered projection chamfered so as to have a peripheral contour line.

  In the above-described ultrasonic welding tip of the present invention, the plurality of protrusions are arranged in a lattice shape, and at least one of the four protrusions arranged at four corners of the plurality of protrusions is the chamfered protrusion. It is preferable. As a result, the chamfered protrusions can be disposed in the vicinity of locations where tearing is particularly likely to occur, so that the tearing of the foil can be effectively reduced.

  Preferably, the plurality of protrusions are arranged in a lattice pattern, and all of the four protrusions arranged at four corners of the plurality of protrusions are the chamfered protrusions. As a result, chamfered protrusions can be arranged at the four corners where breakage is particularly likely to occur, so that the tearing of the foil can be further reduced.

  It is preferable that all the protrusions arranged on the outermost periphery among the plurality of protrusions are the chamfered protrusions. Thereby, tearing of the foil can be further reduced.

  It is preferable that all of the plurality of protrusions are the chamfered protrusions. This minimizes the possibility of foil tearing.

  When the processed surface is viewed from the front, the contour line of the chamfered protrusion may be a substantially square shape having the arcs having a radius R at four corners. In this case, it is preferable that the distance between two opposite sides of the substantially square is the dimension A. Thereby, a chamfering protrusion can be formed by adding a slight processing to a quadrangular frustum-shaped protrusion (non-chamfered protrusion) formed on the processed surface of a conventional chip.

  Or when the said processed surface is seen from the front, the said outline of the said chamfering protrusion may be circular. In this case, the circular diameter may be the dimension A. Thereby, tearing of the foil can be further reduced.

  It is preferable that a concave curved surface that smoothly connects the flat surface of the processed surface and the chamfered protrusion is formed along the contour line of the chamfered protrusion. Thereby, tearing of the foil can be further reduced.

  In the above case, the radius of curvature of the concave curved surface is preferably 0.1 mm or more. Thereby, tearing of the foil can be further reduced.

  It is preferable that chamfering is performed on an outer peripheral end of the processed surface where the processed surface and a side surface adjacent to the processed surface intersect. Thereby, tearing of the foil can be further reduced.

  It is preferable that at least one of the four corner portions of the processed surface is chamfered. More preferably, all four corner portions are chamfered. Thereby, tearing of the foil can be further reduced.

  It is preferable that the chamfering of the outer peripheral end of the processing surface and the chamfering of the corner portion of the processing surface have a substantially cylindrical surface shape with a radius of 0.5 mm or more. Thereby, tearing of the foil can be further reduced.

  The battery manufacturing method of the present invention has a current collector as a base material layer, an electrode portion in which an electrode mixture layer is formed in a predetermined region of the current collector, and the electrode mixture layer is not formed A step of laminating a plurality of electrodes each having an ear portion, and a step of ultrasonically welding the ear portion of the plurality of electrodes and a lead tab thicker than the current collector. Then, in the ultrasonic welding step, the processed surface of the ultrasonic welding tip of the present invention is pressed against the ear portion to ultrasonically weld the ear portion and the lead tab.

  In the method for producing a battery of the present invention, the current collector is preferably an electrolytic copper foil. Thereby, since the electrolytic copper foil is cheaper than the rolled copper foil, the cost of the battery can be reduced.

  Below, this invention is demonstrated in detail, showing suitable embodiment and an Example. However, it goes without saying that the present invention is not limited to the following embodiments and examples. For convenience of explanation, the drawings referred to in the following description show only the main members necessary for explaining the present invention in a simplified manner among the members constituting the embodiment of the present invention. Therefore, the present invention can include any member not shown in the following drawings. Moreover, the dimension of the member in each following figure does not represent the dimension of an actual member, the dimension ratio of each member, etc. faithfully. In each figure, corresponding members are denoted by the same reference numerals, and redundant description thereof is omitted.

  FIG. 1 shows a schematic configuration of an ultrasonic welding machine 1 according to the present invention. The ultrasonic welder 1 includes a transmitter 2 that outputs an electrical signal having a predetermined frequency in the ultrasonic band, and a transducer that converts the electrical signal from the transmitter 2 into mechanical vibration in the ultrasonic band. 3, a booster 4 that converts the mechanical vibration generated by the vibrator 3 into ultrasonic vibration of a predetermined amplitude, a horn 5 that resonates due to the ultrasonic vibration from the booster 4, and a chip provided at one end of the horn 5 10 and an anvil 50 arranged to face the chip 10. The member to be welded is placed on the holding surface 51 of the anvil 50 and supported by the anvil 50. The processed surface 11 of the tip 10 is pressed against the member to be welded on the anvil 50, and a predetermined ultrasonic vibration is applied to the member to be welded through the tip 10.

  The configuration of the ultrasonic welding machine 1 of the present invention is not particularly limited, except for the shape of the processed surface 11 pressed against the member to be welded of the chip 10 described later. For example, the present invention can be applied to any known ultrasonic welding machine. The chip 10 and the horn 5 may be constituted by one integrated part or may be constituted by separate parts.

(Embodiment 1)
FIG. 2A is a plan view of the machining surface 11 of the chip 10 according to the first embodiment of the present invention used in the ultrasonic welding machine 1, and FIG. 2B is a front view thereof. Similar to the processed surface 11 of the conventional chip 10 shown in FIGS. 22A and 22B, the processed surface 11 of the chip 10 of the first embodiment is a flat surface, and 16 protrusions are formed on the processed surface 11 in two rows × It is arranged in a grid in 8 rows. Of the 16 protrusions, the four protrusions 120 arranged at the four corners have the same shape and dimensions, and the remaining 12 protrusions 110 have the same shape and dimensions.

  FIG. 3A is an enlarged plan view of the protrusion 110 arranged at other than the four corners, and FIG. 3B is an enlarged cross-sectional view of the protrusion 110 taken along line 3B-3B in FIG. 3A. The protrusion 110 has a quadrangular pyramid shape (a shape obtained by cutting off the top of the quadrangular pyramid along a plane parallel to its bottom surface), and the processed surface 11 of the conventional chip 10 shown in FIGS. 22A and 22B. It has substantially the same shape as the protrusion 910 formed on the surface. That is, when the projection 110 is viewed in plan as shown in FIG. 3A, the contour line 111 around the projection 110 (that is, the plan view shape of the bottom surface of the projection 110) is a square whose side is A. The outline 113 around the upper surface 112 of the protrusion 110 is also square. However, minute chamfers may be formed at the four corners of the contour line 111 and / or the contour line 113. An inclined surface 114 is formed so as to connect the contour line 111 and the contour line 113.

  4A is an enlarged plan view of the protrusion 120 arranged at the four corners of the 16 protrusions shown in FIG. 2A, and FIG. 4B is an enlarged cross-sectional view of the protrusion 120 taken along line 4B-4B of FIG. 4A. The protrusion 120 has substantially the same shape as the four ridge lines 115 (see FIG. 3A) of the inclined surface 114 of the protrusion 110 having the quadrangular frustum shape shown in FIGS. 3A and 3B chamfered into a substantially cylindrical shape. Have. More specifically, as shown in FIG. 4A, the contour line 121 around the protrusion 120 (that is, the shape of the bottom surface of the protrusion 120 in a plan view) 121 is a square corner having a distance A between two opposite sides. Is a substantially square chamfered by an arc 121r having a radius R. The distance A between the two opposite sides and the radius R satisfy R ≧ A / 6. The value of the radius R can be appropriately changed depending on the size of the protrusion 120 and the like, but is preferably 0.2 mm or more, and more preferably 0.3 mm or more. The outline 123 around the upper surface 122 of the protrusion 120 is also a substantially square with four corners chamfered in an arc shape. An inclined surface 124 is formed so as to connect the contour line 121 and the contour line 123. Therefore, the four ridge lines 125 of the inclined surface 124 are configured by smooth convex curved surfaces (for example, a part of a cylindrical surface).

  In the present invention, the protrusion 120 having an arc-shaped chamfered periphery as shown in FIGS. 4A and 4B is called a “chamfered protrusion”, and the arc-shaped chamfer as shown in FIGS. 3A and 3B is substantially the same. The protrusions 110 that are not provided are called “non-chamfered protrusions”, and the two protrusions are distinguished by the difference in shape.

  The chip 10 of the present embodiment having the processed surface 11 on which the protrusions 110 and 120 are formed as described above is used, for example, when ultrasonically welding the electrode tab and the lead tab of the laminated lithium ion secondary battery. be able to. That is, the tip 10 of Embodiment 1 can be used as the tip 10 shown in FIG. 21 showing the ultrasonic welding method. The processed surface 11 of the chip 10 is pressed against the upper surface of the uppermost negative electrode current collector 65n.

  FIG. 5 is an enlarged plan view showing a welded portion 64n formed by ultrasonic welding 1 using the tip 10 according to the first embodiment. The processed surface 11 was in contact with the surface of the weld 64n shown in FIG. As shown in FIG. 5, concave welding marks 210 and 220 formed by pressing the projections 110 and 120 of the processed surface 11 are formed on the uppermost negative electrode current collector 65n. . The welding mark 210 is formed by the protrusion 110, and is a concave portion having a substantially quadrangular truncated pyramid shape, like the welding mark 920 shown in FIG. On the other hand, the weld mark 220 is formed by the protrusion 120. As can be understood by comparison with the welding mark 210, the outline 221 of the welding mark 220 is a substantially square in which arc-shaped chamfers having relatively large radii are formed at the four corners. As can be easily understood from the difference in the shape of the weld mark 210 and the weld mark 220, the arc chamfering of the outline 221 of the weld mark 220 causes the stress concentration generated in the negative electrode current collector 65n in the vicinity of the weld mark 220. To ease. Therefore, the chamfered protrusion 120 that forms the weld mark 220 has a shape that is more advantageous for reducing the stress concentration generated in the negative electrode current collector 65n near the weld mark than the protrusion 110 that forms the weld mark 210. .

  As described with reference to FIG. 23, in the conventional ultrasonic welding method, a tear 930 is generated in the vicinity of the peripheral portion to which the largest tension is applied, particularly in the vicinity of the welding marks 920 at the four corners. On the other hand, in the first embodiment, the projections at the four corners among the plurality of protrusions arranged in a lattice shape are the chamfered protrusions 120 that do not easily cause stress concentration in the negative electrode current collector 65n. The generation of the 65n break 930 can be effectively suppressed.

  Since it is difficult for the negative electrode current collector 65n to be broken 930, an inexpensive electrolytic copper foil can be used as the negative electrode current collector 65n. Therefore, the cost of the battery 60 can be reduced. Further, unlike the prior art, there is no need for ultrasonic welding with a dummy thin plate sandwiched between the chip 10 and the uppermost negative electrode current collector 65n.

  In the above example, the example in which the protrusions are arranged in 2 rows × 8 columns on the processed surface 11 is shown, but the arrangement of the protrusions is not limited to this. As shown in FIG. 6, the protrusions may be arranged in a grid of m rows × n columns (m and n are integers of 2 or more). In this case, the four protrusions arranged at the four corners can be the chamfered protrusions 120, and the other protrusions can be the non-chamfered protrusions 110. In this case, the same effect as the above example can be obtained.

  2A and 6, only some of the four protrusions arranged at the four corners may be chamfered protrusions 120, and all the other protrusions may be non-chamfered protrusions 110. By arranging the chamfered protrusion 120 only in the vicinity of a portion where the tear 930 is likely to occur, the occurrence of the tear 930 can be effectively prevented.

  Alternatively, at least one of the protrusions arranged on the outermost periphery (in the example of FIG. 6, the protrusions arranged in the first row, the m-th row, the first column, and the n-th column) is used as the chamfering projection 120, All the projections other than those may be non-chamfered projections 110. In some cases, the portion where the tear 930 is likely to occur is other than the vicinity of the four corners. In such a case, the chamfered protrusion 120 is disposed only in the vicinity of the portion where the tear is likely to occur, so Can be prevented.

(Embodiment 2)
The second embodiment is different from the first embodiment regarding the arrangement of the protrusions formed on the processed surface 11 of the chip 10. Hereinafter, the second embodiment will be described with a focus on differences from the first embodiment.

  FIG. 7 is a plan view showing the arrangement of a plurality of protrusions formed on the processed surface 11 of the chip 10 of the second embodiment. Similar to FIG. 6, the processed surface 11 has protrusions arranged in a grid of m rows × n columns. However, unlike FIG. 6, the protrusions arranged on the outermost periphery (that is, the protrusions arranged in the first row, m-th row, first column, and n-th column) are all chamfered projections 120, and the other projections Is a non-chamfered protrusion 110.

  According to the second embodiment, stress concentration is unlikely to occur in the negative electrode current collector 65n at any location around the protrusion group arranged in m rows × n columns, so that the effect of preventing the generation of the tear 930 is prevented. Is further improved.

(Embodiment 3)
The third embodiment is different from the first and second embodiments with respect to the arrangement of the protrusions formed on the processed surface 11 of the chip 10. Hereinafter, the third embodiment will be described focusing on differences from the first and second embodiments.

  FIG. 8 is a plan view showing the arrangement of a plurality of protrusions formed on the processed surface 11 of the chip 10 of the third embodiment. Similar to FIGS. 6 and 7, the processed surface 11 has protrusions arranged in a grid of m rows × n columns. However, unlike FIGS. 6 and 7, all the protrusions (m × n protrusions) are the chamfered protrusions 120, and the non-chamfered protrusions 110 do not exist.

  According to the third embodiment, since all the projections are the chamfered projections 120, stress concentration is unlikely to occur in the negative electrode current collector 65n at any location of the projection group arranged in m rows × n columns. . Therefore, the effect of preventing the occurrence of the tear 930 is further improved.

(Embodiment 4)
In the fourth embodiment, a chamfered protrusion 130 having a shape different from the chamfered protrusion 120 shown in the first to third embodiments is used. Hereinafter, the fourth embodiment will be described focusing on differences from the first to third embodiments.

  FIG. 9A is a plan view of the machining surface 11 of the tip 10 according to Embodiment 4 of the present invention used in the ultrasonic welding machine 1, and FIG. 9B is a front view thereof. Similar to the processing surface 11 of the chip 10 of the first embodiment shown in FIGS. 2A and 2B, 16 protrusions are arranged in a grid in 2 rows × 8 columns on the processing surface 11 of the chip 10 of the fourth embodiment. Has been. Of the 16 protrusions, the four protrusions 130 arranged at the four corners have the same shape and dimensions, and the remaining 12 protrusions 110 have the same shape and dimensions.

  10A is an enlarged plan view of the chamfered protrusion 130 arranged at the four corners of the 16 protrusions shown in FIG. 9A, and FIG. 10B is an enlarged cross-sectional view of the chamfered protrusion 130 taken along the line 10B-10B in FIG. 10A. It is. The protrusion 130 has a smooth convex curved surface that swells in a dome shape. The convex curved surface may be an accurate spherical surface or an aspherical surface obtained by slightly deforming the convex spherical surface. As shown in FIG. 10A, the contour line 131 around the protrusion 130 (that is, the shape of the bottom surface of the protrusion 130 in a plan view) 131 is a circle having a diameter A. That is, the outline 131 of the protrusion 130 corresponds to the case where the radius R of the arc 121r at the four corners is set to half of the dimension A (R = A / 2) in the outline 121 of the protrusion 120 shown in FIG. 4A.

  FIG. 11 is an enlarged plan view showing a welded portion 64n formed by ultrasonic welding 1 using the tip 10 according to the fourth embodiment. The processed surface 11 was in contact with the surface of the weld 64n shown in FIG. As shown in FIG. 11, concave welding marks 210 and 230 formed by pressing the protrusions 110 and 130 on the processed surface 11 are formed on the uppermost negative electrode current collector 65n. . The welding mark 210 is formed by the protrusion 110, and is a concave portion having a substantially quadrangular truncated pyramid shape similar to the welding mark 210 shown in FIG. On the other hand, the welding mark 230 is a curved concave portion formed by the protrusion 130, and its outline 231 is substantially circular. The substantially circular outline 231 alleviates the stress concentration generated in the negative electrode current collector 65 n in the vicinity of the welding mark 230. Therefore, the chamfered protrusion 130 of the fourth embodiment that forms the welding mark 230 has a shape that is advantageous for reducing the stress concentration generated in the negative electrode current collector 65 n in the vicinity of the welding mark 230. Since the chamfered protrusion 130 of the fourth embodiment has a circular outline 131, a greater stress concentration relaxation effect can be obtained as compared to the chamfered protrusion 120 shown in the first to third embodiments.

  Although the chamfering protrusion 130 shown in FIGS. 10A and 10B has a smooth convex curved surface swelled in a dome shape, the present invention is not limited to this. Instead of the chamfered protrusion 130, for example, a chamfered protrusion 140 having a truncated cone shape (a shape obtained by cutting off the top of the cone along a plane parallel to the bottom surface) shown in FIGS. 12A and 12B or a shape similar to this is used. You can also As shown in FIG. 12A, the contour line around the protrusion 140 (that is, the shape of the bottom surface of the protrusion 140 in a plan view) 141 is a circle having a diameter A. Even when the chamfered protrusion 140 is used, the stress concentration generated in the negative electrode current collector 65n can be reduced.

  As described above, according to the fourth embodiment, the protrusions at the four corners among the plurality of protrusions arranged in a lattice shape are the chamfered protrusions 130 and 140 that do not easily cause stress concentration in the negative electrode current collector 65n. Generation | occurrence | production of the tear 930 of the negative electrode collector 65n can be suppressed effectively.

  In the above example, the example in which the projections at the four corners of the 2 rows × 8 columns of projections (see FIGS. 9A and 9B) arranged on the processed surface 11 are the chamfered projections 130 and 140 is shown. It is not limited to this. For example, various arrangement examples of the chamfering protrusions 120 described in the first to third embodiments can be applied to the arrangement of the chamfering protrusions 130 and 140.

(Embodiment 5)
FIG. 13A is a cross-sectional view of a chamfered protrusion 120 ′ according to the fifth embodiment. FIG. 13B is an enlarged cross-sectional view of the portion 13B of FIG. 13A. The chamfering protrusion 120 ′ of the fifth embodiment is a chamfering protrusion 120 having a substantially quadrangular frustum shape shown in FIGS. 4A and 4B in that the concave curved surface 121c is continuously formed along the contour line 121 thereof. And different. The concave curved surface 121c smoothly connects the inclined surface 124 and the flat upper surface of the processed surface 11 of the chip 10. Although not shown, the concave curved surface 121c smoothly connects the ridgeline 125 (see FIG. 4A), which is a smooth convex curved surface, and the processed surface 11 as well. The concave curved surface 121c is continuous in an annular shape so as to surround the chamfered protrusion 120 ′. The planar view shape of the chamfered protrusion 120 ′ is substantially the same as the planar view shape of the chamfered protrusion 120 (see FIG. 4A).

  FIG. 14A is a plan view of a welding mark 220 ′ formed on the upper surface of the uppermost negative electrode current collector 65 n when the chamfered protrusion 120 ′ is pressed against the negative electrode current collector 65 n. FIG. 14B is a cross-sectional view of the welding mark 220 ′ taken along the line 14 </ b> B- 14 </ b> B in FIG. 14A. FIG. 14C is an enlarged cross-sectional view of the portion 14C of FIG. 14B. The welding mark 220 'is a substantially quadrangular frustum-shaped recess. The bottom surface 222 of the welding mark 220 ′ is formed by transferring the upper surface 122 of the protrusion 120 ′, and the inclined surface 224 that connects the contour line 223 of the bottom surface 222 and the contour line 221 of the welding mark 220 ′ is the inclination of the protrusion 220 ′. The surface 124 is formed by being transferred. The shape of the weld mark 220 ′ is substantially the same as the weld mark 220 (see FIG. 5) formed by the chamfered protrusion 120. However, the welding mark 220 ′ is different from the welding mark 220 in that a smooth convex curved surface 221 c is formed along the outline 221. The convex curved surface 221c smoothly connects the inclined surface 224 and the upper surface of the uppermost negative electrode current collector 65n. The convex curved surface 221c is continuous in an annular shape so as to surround the welding mark 220 '. The convex curved surface 221c is formed by transferring the concave curved surface 121c of the chamfered protrusion 120 '. As shown in FIG. 14C, the cross-sectional shape of the convex curved surface 221c has a substantially arc shape.

  According to the present embodiment, since the concave curved surface 121c is formed along the contour line 121 of the chamfered protrusion 120 ′, the contour line 221 is formed on the welding mark 220 ′ formed by transferring the chamfered protrusion 120 ′. A convex curved surface 221c to which the concave curved surface 121c is transferred can be formed. The convex curved surface 221c relieves stress concentration generated in the negative electrode current collector 65n at and near the contour 221. Therefore, the chamfered protrusion 120 ′ having the concave curved surface 121 c can further reduce the occurrence of the break 930 of the negative electrode current collector 65 n compared to the chamfered protrusion 120 having no concave curved surface 121 c.

  A concave curved surface similar to the concave curved surface 121c can be applied to the chamfered protrusions 130 and 140 described in the fourth embodiment.

  15A and 15B show an example in which a concave curved surface is applied to the chamfering protrusion 130 having a smooth convex curved surface swelled in a dome shape shown in FIGS. 10A and 10B. 15A is a cross-sectional view of the chamfered protrusion 130 ′, and FIG. 15B is an enlarged cross-sectional view of the portion 15 </ b> B of FIG. 15A including the outline 131. A concave curved surface 131c is formed along the contour 131 of the chamfered protrusion 130 '. The concave curved surface 131 c smoothly connects the smooth convex curved surface of the protrusion 130 ′ and the flat upper surface of the processed surface 11 of the chip 10. The concave curved surface 131c is continuous in an annular shape so as to surround the chamfered protrusion 130 '. The chamfered protrusion 130 ′ is the same as the chamfered protrusion 130 except that the concave curved surface 131 c is formed. The planar view shape of the chamfered protrusion 130 ′ is substantially the same as the planar view shape of the chamfered protrusion 130 (see FIG. 10A).

  An example in which a concave curved surface is applied to the chamfered protrusion 140 having a substantially truncated cone shape shown in FIGS. 12A and 12B is shown in FIGS. 16A and 16B. 16A is a cross-sectional view of the chamfered protrusion 140 ′, and FIG. 16B is an enlarged cross-sectional view of the portion 16 </ b> B of FIG. 16A including the outline 141. A concave curved surface 141c is formed along the contour line 141 of the chamfered protrusion 140 '. The concave curved surface 141 c smoothly connects the conical surface of the protrusion 140 ′ and the flat upper surface of the processed surface 11 of the chip 10. The concave curved surface 141c is continuous in an annular shape so as to surround the chamfered protrusion 140 '. The chamfering protrusion 140 ′ is the same as the chamfering protrusion 140 except that the concave curved surface 141 c is formed. The planar view shape of the chamfered protrusion 140 ′ is substantially the same as the planar view shape of the chamfered protrusion 140 (see FIG. 12A).

  Although illustration is omitted, as in the case of the chamfered protrusions 120 ′, when the chamfered protrusions 130 ′ and 140 ′ are pressed against the negative electrode current collector and ultrasonic welding is performed, an upper surface of the uppermost negative electrode current collector is formed. A smooth convex curved surface in which the concave curved surfaces 131c and 141c are transferred can be formed on the contour line of the welding mark. The convex curved surface relieves stress concentration generated in the negative electrode current collector at the contour line and in the vicinity thereof. Therefore, the chamfered protrusions 130 ′ and 140 ′ having the concave curved surfaces 131 c and 141 c further reduce the occurrence of the break 930 of the negative electrode current collector 65 n compared to the chamfered protrusions 130 and 140 not having the concave curved surfaces 131 c and 141 c. Can do.

As shown in FIGS. 13B, 15B, and 16B, the shapes of the concave curved surfaces 121c, 131c, and 141c along the cross-sections passing through the contour lines 121, 131, and 141 of the chamfered protrusions 120 ′, 130 ′, and 140 ′ are as follows. A substantially arc shape is preferable. The curvature radii R ₁₂₁ , R ₁₃₁ , and R ₁₄₁ of the concave curved surfaces 121c, 131c, and 141c in the cross section are preferably 0.1 mm or more, more preferably 0.15 mm or more, 0.4 mm or less, and further 0 It is preferable that it is 3 mm or less. Here, the cross section defining the curvature radii R ₁₂₁ , R ₁₃₁ , and R ₁₄₁ is perpendicular to the tangent line of the contour lines ₁₂₁ , ₁₃₁ , and ₁₄₁ at the points where the cross sections intersect on the contour lines ₁₂₁ , ₁₃₁ , and ₁₄₁ . When the curvature radii R ₁₂₁ , R ₁₃₁ , and R ₁₄₁ are smaller than the above numerical range, the effect of the concave curved surfaces 121 c, 131 c, and 141 c to reduce the breakage of the negative electrode current collector is reduced. If the curvature radii R ₁₂₁ , R ₁₃₁ , and R ₁₄₁ are larger than the above numerical range, poor welding is likely to occur.

  As shown in FIGS. 13B, 15B, and 16B, the contour lines 121, 131, and 141 of the chamfered protrusions 120 ′, 130 ′, and 140 ′ are formed on the flat surface of the processing surface 11 and the concave curved surfaces 121c, 131c, and 141c. It is defined by the connection position. The outer dimension A of the chamfered protrusions 120 ′, 130 ′, 140 ′ is defined using the contour lines 121, 131, 141 defined in this way.

  Replacing part or all of the chamfering protrusions 120, 130, and 140 described in the first to fourth embodiments with the chamfering protrusions 120 ′, 130 ′, and 140 ′ of the fifth embodiment including the concave curved surfaces 121c, 131c, and 141c. Can do.

(Embodiment 6)
As shown in FIG. 2A, the processing surface 11 of the chip 10 has a substantially rectangular shape in plan view, and the processing surface 11 is adjacent to the four side surfaces 12a, 12b, 12c, and 12d. Preferably, the side surfaces 12a, 12b, 12c, and 12d are substantially perpendicular to the processed surface 11. 17A is a cross-sectional view of the chip 10 taken along line 17A-17A in FIG. 2A, and FIG. 17B is a cross-sectional view of the chip 10 taken along line 17B-17B in FIG. 2A. In FIGS. 17A and 17B, the projections 110 and 120 that should be visible behind the cross section are not shown in order to simplify the drawing. 17C is an enlarged plan view of the portion 17C of FIG. 2A including the corner portion of the processed surface 11. FIG.

  As shown in FIGS. 17A and 17B, chamfers 13 a, 13 b, 13 c, and 13 d are applied to the outer peripheral ends of the processed surface 11 where the processed surface 11 and the side surfaces 12 a, 12 b, 12 c, and 12 d intersect. Yes. The shapes of the chamfers 13a, 13b, 13c, and 13d are inclined planes (so-called “so-called“ R surfaces ”) that are obliquely intersected with any of the substantially cylindrical surface (so-called“ R surface ”), the processed surface 11, and the side surfaces 12a, 12b, 12c, and 12d. Although it can be arbitrarily selected from known chamfered shapes such as “C surface”), it is preferably a convex curved surface that smoothly connects the processed surface 11 and the side surfaces 12a, 12b, 12c, and 12d, and is an R surface. Is more preferable.

  As shown in FIG. 17C, chamfering 14 is also given to the corner portion of the processed surface 11 of the chip 10. In FIG. 17C, only one of the four corner portions of the processed surface 11 is illustrated, but the same chamfer 14 is also applied to the other three corner portions. The shape of the chamfer 14 is a well-known chamfered shape such as a substantially cylindrical surface (so-called “R surface”) and an inclined plane (so-called “C surface”) that obliquely intersects any of two adjacent side surfaces sandwiching the corner portion. Can be arbitrarily selected from the above, but is preferably a convex curved surface that smoothly connects two adjacent side surfaces, and more preferably an R surface.

  The processed surface 11 of the chip 10 is pressed against the negative electrode current collector 65n as shown in FIG. At this time, the processed surface 11 is in contact with the uppermost negative electrode current collector 65n. When chamfers 13 a, 13 b, 13 c, 13 d, and 14 are not provided around the processed surface 11 of the chip 10, the negative electrode current collector 65 n is locally pressed at the outer peripheral edge or corner portion of the processed surface 11. Therefore, it is difficult for the uppermost negative electrode current collector 65n to move with respect to the processed surface 11 particularly in the locally pressed position. In this state, when the protrusion formed on the processed surface 11 is pushed into the negative electrode current collector 65n, the negative electrode current collector 65n is greatly extended, so that the tear 930 (see FIG. 23) is likely to occur.

  On the other hand, when chamfers 13a, 13b, 13c, 13d, and 14 are provided around the machining surface 11 as in the sixth embodiment, the outer peripheral edge and corner portion of the machining surface 11 are negative electrode current collectors. Since the local pressing force applied to the body 65n is reduced, the action of restricting the movement of the uppermost negative electrode current collector 65n with respect to the processed surface 11 is particularly relaxed. Accordingly, when the protrusion formed on the processed surface 11 is pushed into the negative electrode current collector 65n, the negative electrode current collector 65n can be displaced with respect to the processed surface 11, so that it is broken 930 (see FIG. 23). Can be further reduced.

In this example, cylindrical chamfering with a radius R ₁₃ is performed as the chamfers ₁₃ a, 13 b, 13 c, and 13 d, and cylindrical chamfering with a radius R ₁₄ is performed as the chamfering 14. The radii R ₁₃ and R ₁₄ are preferably 0.5 mm or more, more preferably 0.7 mm or more, and preferably 2 mm or less, more preferably 1.5 mm or less. If the radii R ₁₃ and R ₁₄ are smaller than the above numerical range, it is difficult to obtain the effect of reducing the occurrence of the tear 930 (see FIG. 23). If the radii R ₁₃ and R ₁₄ are larger than the above numerical range, the time required for the chamfering process becomes long.

  It is preferable that a chamfer formed by intersecting a chamfer 14 between two adjacent side surfaces and a chamfer formed at the outer peripheral end of the processed surface 11 is formed at the top of each corner portion of the processed surface 11. . The chamfer at the top is preferably a smooth convex curved surface, more preferably a substantially spherical surface. The chamfer at the top is particularly preferably a spherical surface having a radius of 0.5 mm or more, further 0.7 mm or more, 2 mm or less, and further 1.5 mm or less.

  All or only a part of the chamfers 13a, 13b, 13c, 13d, and 14 described in the fifth embodiment can be applied to the chip 10 described in the first to fifth embodiments.

  In the present invention, the processing method of the chamfered protrusions 120, 130, 140, 120 ', 130', 140 'is not particularly limited. For example, after forming the non-chamfered protrusion 110 on the processed surface 11 of the chip 10 by a known method, the chamfered protrusion 120, 130, 140, 120 ′, 130 ′, 140 ′ is formed by chamfering using a file or the like. Can be formed.

  In said Embodiment 1-6, although several protrusion was arrange | positioned on the processing surface 11 at the grid | lattice form, this invention is not limited to this. For example, a plurality of protrusions may be arranged in a honeycomb shape.

  In the first to sixth embodiments, the vertical and horizontal dimensions of the protrusions 110, 120, 130, 140, 120 ′, 130 ′, and 140 ′ when the processed surface 11 is viewed from the front are all A. The vertical dimension and the horizontal dimension may be different. The planar view shape of the protrusion may be an arbitrary shape such as a substantially rectangular shape, a substantially regular hexagonal shape in addition to a substantially square shape. The outer dimension A of the contour line around the protrusion is defined by the outer dimension along the direction in which the outer dimension of the contour line is minimized. For example, when the planar view shape of the projection is substantially rectangular, the outer dimension A means the dimension in the short side direction, and when the planar view shape of the projection is substantially regular hexagon, the outer dimension A is It means the distance between two opposite sides.

  In the first to sixth embodiments described above, the case where the negative electrode welded portion 64n is formed by the tip 10 of the present invention has been described. However, the positive electrode welded portion 64p can also be formed, and in this case, the same effect as described above can be obtained.

(Embodiment 7)
The ultrasonic welding machine 1 provided with the chip 10 of the present invention shown in the first to sixth embodiments can be preferably used for welding foil-like materials. Among them, the battery, particularly the laminated lithium ion shown in FIG. It can be used for welding the electrode tab of the secondary battery 60 and the lead tab.

  The general configuration of the lithium ion secondary battery 60 will be outlined below.

  The positive electrode 61p has a structure in which, for example, a layer (positive electrode mixture layer) 66p made of a positive electrode mixture containing a positive electrode active material, a conductive additive, a binder, and the like is formed on one surface or both surfaces of the current collector 65p.

A positive electrode active material consists of an active material which can occlude / release lithium ion. Such a positive electrode active material includes, for example, lithium having a layered structure represented by Li _{1 + x} MO ₂ (−0.1 <x <0.1, M: Co, Ni, Mn, Al, Mg, etc.) Transition metal oxide, LiMn ₂ O ₄ , lithium manganese oxide having a spinel structure in which part of the element is replaced with another element, and olivine type represented by LiMPO ₄ (M: Co, Ni, Mn, Fe, etc.) It preferably consists of any one of compounds.

Lithium-containing transition metal oxide of the above layered structure, for _{example, LiCoO 2, LiNi 1-x} Co xy Al y O 2 (0.1 ≦ x ≦ 0.3,0.01 ≦ y ≦ 0.2), And an oxide containing at least Co, Ni and Mn (LiMn _1/3 Ni _1/3 Co _1/3 O ₂ , LiMn _5/12 Ni _5/12 Co _1/6 O ₂ , LiNi _3/5 Mn _1/5 Co _1/5 O ₂ or LiNi _0.5 Co _0.2 Mn _0.3 ) is preferable.

  The current collector 65p of the positive electrode 61p is preferably made of, for example, an aluminum foil or an aluminum alloy foil. The thickness of the current collector 65p varies depending on the size and capacity of the battery, but is preferably 0.01 to 0.02 mm, for example.

  The positive electrode 61p is manufactured by the following method. A positive electrode mixture containing the above-described positive electrode active material, a conductive additive such as graphite, acetylene black, carbon black, and fibrous carbon, and a binder such as polyvinylidene fluoride (PVDF) is used as N-methyl-2-pyrrolidone. A paste-like or slurry-like composition uniformly dispersed using a solvent such as (NMP) is prepared (the binder may be dissolved in the solvent). This composition is intermittently applied onto a strip-shaped current collector and dried. You may adjust the thickness of a positive mix layer by press processing as needed. The long positive electrode substrate (electrode substrate) thus obtained is cut into a predetermined shape using, for example, a Thomson blade to obtain the positive electrode 61p.

  The thickness of the positive electrode mixture layer 66p in the positive electrode 61p is preferably 30 to 100 μm per side. Moreover, it is preferable that content of each structural component in the positive mix layer 66p is positive electrode active material: 90-98 mass%, conductive support agent: 1-5 mass%, binder: 1-5 mass%.

  The positive electrode lead tab 63p is preferably made of aluminum or an aluminum alloy. The thickness of the positive electrode lead tab 63p is preferably 20 to 300 μm.

  In FIG. 19, the positive electrode lead tab 63 p is led out to the outside of the outer package 68, but a positive electrode terminal of a different member is connected to the positive electrode lead tab 63 p and the positive electrode terminal is led out of the outer package 68. Also good. The material of such a positive electrode terminal is determined from the viewpoint of facilitating connection with a device that uses the battery 60. For example, aluminum or an aluminum alloy can be used. Moreover, it is preferable that the thickness of a positive electrode terminal is 50-300 micrometers.

  As a method for connecting the ear 62p of the positive electrode 61p and the positive lead tab 63p, ultrasonic welding using the tip 10 of the present invention can be used. In addition to ultrasonic welding, various methods such as resistance welding, laser welding, caulking, and adhesion using a conductive adhesive can also be used.

  The negative electrode 61n has, for example, a structure in which a layer (negative electrode mixture layer) 66n containing a negative electrode active material capable of inserting and extracting lithium ions is formed on one side or both sides of the current collector 65n.

  Negative electrode active materials include graphite, pyrolytic carbons, cokes, glassy carbons, fired organic polymer compounds, mesocarbon microbeads (MCMB), and carbon that can occlude and release lithium ions such as carbon fibers. It is preferable that it consists of 1 type, or 2 or more types of mixtures of type | system | group material.

Alternatively, the negative electrode active material may be an element such as Si, Sn, Ge, Bi, Sb, or In, an alloy of Si, Sn, Ge, Bi, Sb, or In, a lithium-containing nitride, or a lithium metal such as lithium oxide. It is preferably made of any one of a compound (LiTi ₃ O ₁₂ or the like) that can be charged and discharged at a near low voltage, lithium metal, and a lithium / aluminum alloy.

  A copper foil is suitable as the current collector 65n of the negative electrode 61n. Copper foils are roughly classified into electrolytic copper foils and rolled copper foils depending on the manufacturing method. Electrolytic copper foil is relatively inexpensive. The thickness of the current collector 65n varies depending on the size or capacity of the battery, but is preferably 0.005 to 0.02 mm, for example.

  The negative electrode 61n is produced by the following method. The negative electrode active material described above, a binder (such as a mixed binder of rubber binder such as PVDF or styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC)), and graphite, acetylene black, carbon black, etc. A paste-like or slurry-like composition in which a negative electrode mixture containing a conductive aid or the like is uniformly dispersed using a solvent such as NMP or water is prepared (the binder may be dissolved in the solvent). . This composition is intermittently applied onto a strip-shaped current collector and dried. You may adjust the thickness or density of a negative mix layer by press processing as needed. The long negative electrode substrate (electrode substrate) thus obtained is cut into a predetermined shape using, for example, a Thomson blade to obtain a negative electrode 61n.

  The thickness of the negative electrode mixture layer 66n in the negative electrode 61n is preferably 30 to 100 μm per side. Moreover, it is preferable that content of each structural component in the negative mix layer 66n is negative electrode active material: 90-98 mass%, binder: 1-5 mass%. Moreover, when using a conductive support agent, it is preferable that content of the conductive support agent in 66 n of negative mix layers is 1-5 mass%.

  The negative electrode lead tab 63n is preferably made of copper. If necessary, nickel plating or the like may be applied to the surface. The thickness of the negative electrode lead tab 63n is preferably 20 to 300 μm.

  In FIG. 19, the negative electrode lead tab 63 n is led out to the outside of the outer package 68, but a negative electrode terminal of a different member is connected to the negative electrode lead tab 63 n and the negative electrode terminal is led out of the outer package 68. Also good. The material of such a negative electrode terminal is determined from the viewpoint of facilitating connection with a device that uses the battery 60. For example, nickel, nickel-plated copper, nickel-copper clad, or the like can be used. Moreover, it is preferable that the thickness of a negative electrode terminal is 50-300 micrometers similarly to a positive electrode terminal.

  As a method for connecting the ear portion 62n of the negative electrode 61n and the negative electrode lead tab 63n, ultrasonic welding using the tip 10 of the present invention can be used. As described above, since the chip 10 of the present invention can reduce the occurrence of breakage of the metal foil in contact with the chip 10, an electrolytic copper foil that is relatively inferior in elongation resistance is used as the negative electrode current collector 65n. However, it is possible to manufacture a battery in which the ear 62n made of the negative electrode current collector 65n is not broken. As a result, the cost of the battery can be reduced by using a relatively inexpensive electrolytic copper foil. In addition to the ultrasonic welding, various methods such as resistance welding, laser welding, caulking, adhesion with a conductive adhesive, and the like can be used as a method for connecting the ear 62n and the negative electrode lead tab 63n.

  The separator 66 includes a porous film that separates the positive electrode 61p and the negative electrode 61n and transmits lithium ions. The separator 66 preferably has a safety mechanism (shutdown characteristic) that melts and closes the hole when the battery 60 abnormally generates heat and reaches a high temperature (for example, 100 to 140 ° C.). From such a viewpoint, the porous film is preferably made of a thermoplastic resin having a melting point of about 80 to 140 ° C., and specifically, preferably made of a polyolefin polymer such as polypropylene or polyethylene. The thickness of the porous film is not particularly limited, but is preferably 10 to 50 μm.

  The separator 66 may be formed by coating a plate-like inorganic fine particle layer on the porous film. Thereby, the thermal contraction of the separator 66 at the time of abnormal heat generation can be suppressed, and safety can be improved.

  Alternatively, the separator 66 may have a laminated structure of the porous film and the heat resistant porous substrate. As the heat resistant porous substrate, for example, a fibrous material having a heat resistant temperature of 150 ° C. or higher can be used. The fibrous material may be formed of at least one material selected from the group consisting of cellulose and its modified products, polyolefin, polyethylene terephthalate, polybutylene terephthalate, polypropylene, polyester, polyacrylonitrile, aramid, polyamideimide, and polyimide. it can. Specifically, it is preferably made of a nonwoven fabric made of the above materials.

  “Heat resistance” of the porous substrate means that a substantial dimensional change due to softening or the like does not occur. Specifically, is the upper limit temperature (heat resistant temperature) at which the rate of shrinkage (shrinkage ratio) with respect to the length of the porous substrate at room temperature maintained at 5% or less is sufficiently higher than the shutdown temperature of the separator? The heat resistance is evaluated depending on whether or not. In order to increase the safety of the laminated battery after shutdown, it is desirable that the porous substrate has a heat resistance higher by 20 ° C. than the shutdown temperature. More specifically, the heat resistance temperature of the porous substrate is 150 ° C. It is preferable that the temperature is higher than or equal to ° C, and more preferably higher than or equal to 180 ° C.

As the electrolytic solution, for example, a solution (nonaqueous electrolytic solution) in which a solute such as LiPF ₆ or LiBF ₄ is dissolved in a high dielectric constant solvent or an organic solvent can be used. As the high dielectric constant solvent, any of ethylene carbonate (EC), propylene carbonate (PC), and γ-butyrolactone (BL) can be used. As the organic solvent, a low viscosity solvent such as linear dimethyl carbonate (DMC), diethyl carbonate (DEC), or methyl ethyl carbonate (EMC) can be used.

  As the solvent of the electrolytic solution, it is preferable to use a mixed solvent of the above-described high dielectric constant solvent and low viscosity solvent. Alternatively, PVDF, a rubber-based material, an alicyclic epoxy, a material having an oxetane-based three-dimensional crosslinked structure, and the like may be mixed and solidified into the above-described solution to form a polymer electrolyte.

  The separator 66 is interposed between the positive electrode 61p and the negative electrode 61n, and the positive electrode 61p and the negative electrode 61n are alternately stacked to form an electrode laminate 67.

  There is no restriction | limiting in particular in the production method of the electrode laminated body 67. FIG. For example, the band-shaped separator 66 is alternately zigzag-folded by alternately repeating mountain folds and valley folds at regular intervals, and the positive electrode 61p is sandwiched between the one surface side of the separator 66 and each valley fold portion, and the other surface side Thus, the electrode laminate 67 can be formed by sandwiching the negative electrode 61n in each valley folded portion. Alternatively, the electrode stack 67 may be formed by forming a plurality of rectangular bags with the separators 66 and inserting the positive electrodes 61p into the bags made of the separators 66 alternately with the negative electrodes 61n. .

  The positive electrode lead tab 63p is connected to the positive electrode ears 62p of the plurality of positive electrodes 61p protruding from the electrode laminate 67 thus obtained. Similarly, the negative electrode lead tab 63n is connected to the negative electrode ears 62n of the plurality of negative electrodes 61n protruding from the electrode laminate 67.

  Two laminate sheets 69 having a substantially rectangular shape are arranged above and below the electrode laminate 67 thus obtained, and two laminate sheets are disposed along three sides excluding the side where the positive electrode lead tab 63p and the negative electrode lead tab 63n are formed. 69 is heat-sealed to form a laminate sheet 69 into a bag shape. Rather than using two laminate sheets, one rectangular laminate sheet is folded and stacked so as to sandwich the electrode laminate 67, and heat-sealed along two opposing sides to form a laminate sheet in a bag shape It may be formed. Thereafter, an electrolytic solution is injected into the bag of the laminate sheet 69. Finally, the laminate sheet 69 is heat-sealed together with the positive and negative lead tabs 63p and 63n along the side that is not heat-sealed, whereby the lithium ion secondary battery 60 is obtained.

  There is no restriction | limiting in particular in the structure of the laminate sheet 69, For example, the well-known laminate sheet currently used as an exterior material of a laminate-type lithium ion secondary battery can be used. For example, a multilayer sheet in which a modified polyolefin layer is laminated as a heat-fusible resin layer on one side of a base layer made of aluminum can be used.

  In the above example, the positive electrode lead tab 63p and the negative electrode lead tab 63n are drawn from the same short side of the substantially rectangular laminate sheet 69, but may be drawn from different sides.

  Although the example of the laminated lithium ion secondary battery has been described above, the chip 10 of the present invention can also be used for manufacturing a lithium ion secondary battery other than the laminated type.

(Evaluation Test 1)
An electrode laminate 67 (see FIG. 19) for the laminated lithium ion secondary battery 60 was produced as follows.

  As the positive electrode current collector 65p, an aluminum foil having a thickness of 15 μm was used. A positive electrode mixture layer 66p having a thickness of 110 μm was applied and formed in predetermined regions on both surfaces of the current collector 65p to obtain a positive electrode 61p.

  An electrolytic copper foil having a thickness of 10 μm was used as the negative electrode current collector 65n. A negative electrode mixture layer 66n having a thickness of 126 μm was applied and formed in a predetermined region on both surfaces of the current collector 65n to obtain a negative electrode 61n.

  A strip-shaped separator 66 made of a porous film and having a thickness of 21 μm is folded in a zigzag shape, and the positive electrode 61p is sandwiched from one side of the separator 66 to each valley fold, and the above-mentioned each valley fold from the other side. The negative electrode electrode 61n was sandwiched, so that an electrode laminate 67 in which 22 positive electrodes 61p and 23 negative electrodes 61n were alternately laminated via separators 66 was obtained.

  As shown in FIG. 21, the ears 62n of the 23 negative electrodes 61n protruding from one side of the electrode laminate 67 are superimposed on a lead tab 63n (20 mm width Cu—Ni) having a thickness of 285 μm and a width of 20 mm, Both were joined by ultrasonic welding. The lead tab 63n is obtained by performing nickel plating on both surfaces of a copper thin plate.

In the embodiment, the chip 10 having the processing surface 11 in which 16 chamfering protrusions 130 ′ having convex curved surfaces swelled in a dome shape shown in FIG. 15A are arranged in a grid in 2 rows × 8 columns is used. Then, ultrasonic welding was performed. The diameter A (see FIG. 10A) of the circular outline 131 of the protrusion 130 ′ when the processed surface 11 was viewed in plan was 0.6 mm. The height of the protrusion 130 ′ was 0.3 mm. A concave curved surface 131c (see FIG. 15B) continuously formed in an annular shape around the protrusion 130 ′ along the contour line 131 had an arc-shaped cross section with a curvature radius R ₁₃₁ of 0.2 mm. Cylindrical chamfers 13 a, 13 b, 13 c, and 13 d (see FIGS. 17A and 17B) having a radius R ₁₃ of 1 mm are applied to the outer peripheral end of the processing surface 11 of the chip 10. The part had a cylindrical chamfer 14 (see FIG. 17C) with a radius R ₁₄ of 1 mm. The processed surface 11 on which such a protrusion 130 ′ was formed was pressed against the current collector 65 n constituting the ear portion 62 n and ultrasonically welded. Ten electrode laminates 67 were ultrasonically welded to the lead tabs 63n.

In the comparative example, ultrasonic welding was performed under the same conditions as in the example except that the tip 10 different from that in the example was used. On the processed surface 11 of the chip 10 used in the comparative example, the 16 non-chamfered projections 110 shown in FIGS. 3A and 3B were arranged in a grid of 2 rows × 8 columns. The outline 111 of the non-chamfered protrusion 110 when the processed surface 11 is viewed in plan is a square having a side length A of 1.2 mm, and the outline 113 of the upper surface 112 is a square having a side length of 0.6 mm. . The height of the protrusion 110 was 0.3 mm. The arrangement pitch of the protrusions 110 in the vertical and horizontal directions was the same as that of the protrusion 130 ′ of the chip 10 of the example. The concave curved surface 121c (see FIG. 13B) was not formed on the contour line 111 around the protrusion 110 (that is, the curvature radius R ₁₂₁ <0.05 mm). Chamfers 13a, 13b, 13c, and 13d (see FIGS. 17A and 17B) of the outer peripheral edge of the machining surface 11 and chamfers 14 at four corners of the machining surface 11 (see FIG. 17C) formed in the chip 10 of the example. Were not applied in the comparative examples (that is, R ₁₃ <0.1 mm, R ₁₄ <0.1 mm). Using the chip 10 of the above comparative example, ultrasonic welding of the 10 electrode laminates 67 to the lead tabs 63n was performed in the same manner as in the example.

  For each of the ten samples of the example and the comparative example, each ultrasonic weld 64n was observed with a digital microscope, and it was determined whether or not the current collector 65n constituting the ear 62n was broken.

  As a result, in the example, the current collector 65n was not broken in any of the ten samples. On the other hand, in the comparative example, the uppermost current collector 65n was broken in all of the ten samples. From this, it was confirmed that the chip 10 used in the example is effective in preventing the current collector from being broken.

(Evaluation test 2)
The same 23 negative electrode current collectors 65n used in the evaluation test 1 in which the negative electrode mixture layer 66n was not formed were prepared. The ears 62n of the 23 negative electrode current collectors 65n were superposed on the same lead tab 63n as in the evaluation test 1, and these were joined by ultrasonic welding. The conditions for ultrasonic welding were the same as those in Evaluation Test 1. Ten samples were obtained for each of the examples and comparative examples.

  For each sample, a tensile test was performed on the uppermost negative electrode current collector 65n on which the chip 10 was pressed. That is, with the lead tab 63n held, a gradually increasing tension was applied to the uppermost negative electrode current collector 65n, and the tension at the time when the negative electrode current collector 65n was broken was measured. The strength (unit: N / 10 mm) of the negative electrode current collector was determined by converting the tension (unit: N) into a tension per 10 mm width of the ear 62n.

  The results are shown in FIG. The upper graph of FIG. 18 shows the intensity | strength of the negative electrode electrical power collector of each 10 samples of an Example and a comparative example. Below FIG. 18, the average value, maximum value, minimum value, and standard deviation of the intensity for each of the ten samples of the example and the comparative example are shown. From FIG. 18, it was confirmed that the chip 10 used in the example is effective in preventing the current collector from being broken since the degree of reducing the tensile strength of the current collector is small.

  The battery manufacturing method of the present invention can be preferably used for manufacturing a secondary battery in which sheet-like positive electrodes and sheet-like negative electrodes are alternately arranged via separators.

  The tip for ultrasonic welding and the ultrasonic welder of the present invention can be preferably used in a step of ultrasonic welding by pressing a tip against a foil-like member to be welded. In particular, it can be particularly preferably used in the step of ultrasonic welding the current collector and the lead tab constituting the electrode of the secondary battery.

DESCRIPTION OF SYMBOLS 1 Ultrasonic welding machine 5 Horn 10 Tip 11 Processing surface 13a, 13b, 13c, 13d Chamfering 14 Chamfering 50 Anvil 60 Laminate type lithium ion secondary battery 62p, 62n Ear part 63p, 63n Lead tab 65p, 65n Current collector 66p, 66n Electrode mixture layer 120, 130, 140, 120 ', 130', 140 'Chamfering protrusion 121, 131, 141 Contour line 121c, 131c, 141c Concave surface 121r Arc

Claims (15)

Ultrasonic welding for ultrasonic welding of a member to be welded by applying ultrasonic vibration to the member to be welded while pressing the workpiece surface against the member to be welded while having a machining surface formed with a plurality of protrusions A chip,
When the processed surface is viewed from the front, at least one protrusion arranged on the outermost periphery among the plurality of protrusions is an arc having a radius R that satisfies R ≧ A / 6 when the outer dimension in one direction is A. A tip for ultrasonic welding, which is a chamfered projection chamfered so as to have a peripheral contour line.   2. The ultrasonic welding tip according to claim 1, wherein the plurality of protrusions are arranged in a lattice shape, and at least one of the four protrusions arranged at four corners of the plurality of protrusions is the chamfered protrusion.   The ultrasonic welding tip according to claim 1 or 2, wherein the plurality of protrusions are arranged in a lattice shape, and all of the four protrusions arranged at four corners of the plurality of protrusions are the chamfered protrusions.   The ultrasonic welding tip according to any one of claims 1 to 3, wherein all of the plurality of protrusions arranged on the outermost periphery are the chamfered protrusions.   The ultrasonic welding tip according to claim 1, wherein all of the plurality of protrusions are the chamfered protrusions.   When the processed surface is viewed from the front, the contour line of the chamfered protrusion is a substantially square having the arcs having a radius R at four corners, and the distance between two sides of the substantially square facing each other is the dimension A. Item 6. The ultrasonic welding tip according to any one of Items 1 to 5.   The ultrasonic welding tip according to any one of claims 1 to 5, wherein when the processed surface is viewed from the front, the contour line of the chamfered protrusion is circular and the diameter of the circular is the dimension A.   The ultrasonic welding tip according to any one of claims 1 to 7, wherein a concave curved surface that smoothly connects the flat surface of the processed surface and the chamfered protrusion is formed along the contour line of the chamfered protrusion. .   The tip for ultrasonic welding according to claim 8, wherein a radius of curvature of the concave curved surface is 0.1 mm or more.   The ultrasonic welding tip according to any one of claims 1 to 9, wherein a chamfer is applied to an outer peripheral end of the processed surface where the processed surface and a side surface adjacent to the processed surface intersect.   The ultrasonic welding tip according to claim 1, wherein at least one of the four corner portions of the processed surface is chamfered.   The ultrasonic welding tip according to claim 10 or 11, wherein the chamfer has a substantially cylindrical surface shape having a radius of 0.5 mm or more. A chip that is pressed against the member to be welded and applies ultrasonic vibration to the member to be welded;
An anvil disposed opposite the tip and supporting the member to be welded;
The tip is provided at one end, and an ultrasonic welding machine provided with a horn that resonates by the ultrasonic vibration,
An ultrasonic welding machine, wherein the tip is a tip for ultrasonic welding according to any one of claims 1 to 12. A current collector as a base material layer, and a plurality of electrode portions each having an electrode mixture layer formed in a predetermined region of the current collector, and ear portions each having no electrode mixture layer formed thereon Laminating electrodes;
A method of manufacturing a battery comprising ultrasonic welding the ear tabs of the plurality of electrodes and a lead tab thicker than the current collector,
In the ultrasonic welding step, a battery for ultrasonically welding the ear portion and the lead tab by pressing the processed surface of the ultrasonic welding tip according to any one of claims 1 to 12 to the ear portion. Production method.   The method of manufacturing a battery according to claim 14, wherein the current collector is an electrolytic copper foil.

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