JP2009289714A - Lithium-ion secondary battery and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium-ion secondary battery capable of ensuring the battery performance. <P>SOLUTION: A lithium-ion secondary battery 13 has a battery can 11, and an electrode group 3 with positive/negative electrode plates wound via a separator is housed inside the battery can 11. A plurality of current collection tabs derived from one side of the positive/negative electrode plates, respectively, are disposed on the opposite side of the electrode group 3 with respect to one another. Current collection rings 4, 7 are disposed in opposition to each other at both ends of the electrode group 3. At the outer peripheral surfaces of the current collection rings 4, 7, each of the ends of the current collection tabs 6, 8 is collected, and metal stiffening plates 5, 9 are disposed over the almost entire circumference so that both ends of the plates are never overlapped. The stiffening plates 5, 9 are bonded over the entire circumference by means of the laser beam irradiated almost orthogonally to the outer peripheral surfaces of the current collection rings 4, 7. The ends of the current collection tabs 6, 8 are bonded to be sandwiched between the current collection rings 4, 7 and the stiffening plates 5, 9. The laser beam is not oriented to the electrode group 3 during the laser welding. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lithium ion secondary battery and a method for manufacturing the same, and in particular, includes a group of electrodes in which a positive and negative electrode plate is wound through a separator, and a positive and negative current collecting tab is derived from one side of the positive and negative electrode plates, respectively. The present invention relates to a lithium ion secondary battery disposed on opposite sides of an electrode group and a method for manufacturing the same.

  Conventionally, lithium ion secondary batteries have been widely used in various applications. In particular, a cylindrical wound lithium ion secondary battery in which a group of electrodes in which a strip-like positive and negative electrode plate is wound in a spiral shape in cross section around a shaft via a separator is housed in a cylindrical battery can is a high energy density. Taking advantage of a certain merit, it is used in portable devices such as VTR cameras, notebook computers or mobile phones. On the other hand, the cylindrical wound lithium ion secondary battery is also used as an in-vehicle power source of an electric vehicle (EV) or a hybrid electric vehicle (HEV) as a secondary battery for large current charge / discharge applications.

  In general, in a wound secondary battery for large current charge / discharge applications, a plurality of current collecting tabs are led out from one side of the positive and negative electrode plates in order to reduce the internal resistance of the battery. The current collecting tabs are respectively arranged on opposite sides of the electrode group, and the end surfaces of the current collecting tabs intersect the surfaces facing the electrode group of the current collecting parts arranged to face the end surfaces of the electrode group, respectively. Collected and joined together. Examples of a method for joining the current collecting tab to the current collecting component include ultrasonic joining and laser welding.

  Ultrasonic bonding is a method of bonding metals by applying vibration to the members to be bonded, removing the oxide film formed on the metal surfaces, and diffusing metal atoms between the exposed metal surfaces. is there. However, when a plurality of current collecting tabs are collected and ultrasonic bonding is performed as described above, the current collecting tabs may be subject to fatigue failure depending on conditions such as applied pressure, ultrasonic amplitude, vibration time, and frequency. . On the other hand, in laser welding, the energy density is very high because light of a single wavelength is collected at an extremely small point. For this reason, the influence of heat on the surroundings due to welding is small, and the workpieces can be melted and deeply joined in the irradiation direction at high speed. For example, a technique is disclosed in which a current collecting tab is joined to a current collecting component by irradiating a laser beam in a direction (vertical direction) along a side circumferential surface intersecting a surface facing the electrode group of the current collecting component (patent) Reference 1).

JP-A-9-92335

  However, in a wound lithium ion secondary battery, since the positive and negative electrode plates from which a plurality of current collecting tabs are drawn are wound, when the current collecting tabs are collected on the side surface of the current collecting component, the current collecting The density of tabs overlaps. For this reason, the heat input energy of the laser light becomes excessive at a place where the overlap is sparse, and the laser light may penetrate the current collecting tab and the current collecting component. In the technique of Patent Document 1, laser light is irradiated in a direction along a side circumferential surface intersecting with a surface facing the electrode group of the current collecting component, that is, in the direction of the electrode group. There is a possibility of damaging the electrode group and impairing battery performance. Furthermore, when the current collecting component and the electrode group are close to each other, it is difficult to confirm whether or not the laser beam has penetrated.

  An object of the present invention is to provide a lithium ion secondary battery capable of ensuring battery performance and a method for manufacturing the same, in view of the above-described case.

  In order to solve the above problems, a first aspect of the present invention includes an electrode group in which a positive and negative electrode plate is wound through a separator, and a positive and negative current collecting tab is led out from one side of the positive and negative electrode plate, respectively. In the lithium ion secondary battery disposed on the opposite side of the electrode group, at least one of the positive electrode current collecting tab and the negative electrode current collecting tab is the current collecting component disposed opposite to the end surface of the electrode group. It is characterized in that it is bonded to a side peripheral surface intersecting with a surface facing the electrode group by a laser beam irradiated in a substantially horizontal direction.

  In the first aspect, since the laser is irradiated in a substantially horizontal direction on the side peripheral surface that intersects the surface facing the electrode group of the current collecting component, damage to the electrode group can be prevented and battery performance can be ensured.

  In this case, it is preferable that at least one of the positive electrode current collecting tab and the negative electrode current collecting tab is sandwiched and joined between the side peripheral surface of the current collecting component and the metal backing plate. At this time, if it is arranged so as to be opposed to the side peripheral surface of the current collector component so that the overlapping of both ends of the contact plate is not formed, a gap is not formed between the current collector component and the contact plate, Since it arrange | positions, poor welding can be suppressed and a current collection tab and current collection components can be joined reliably. The current collecting component and the contact plate to which the negative electrode current collecting tab is bonded may be made of copper, nickel, an alloy of copper and nickel, or a multilayer body of copper and nickel, respectively.

  According to a second aspect of the present invention, there is provided a method of manufacturing a lithium ion secondary battery according to claim 1, wherein a metal backing plate is applied so that the overlapping of both ends of the plate is not formed. It arrange | positions facing the surrounding side surface of the said current collection component, and welds over the perimeter of the said contact plate, after welding the both ends of the said contact plate with a spot, respectively.

  According to the present invention, since the laser is irradiated in a substantially horizontal direction on the side circumferential surface that intersects the surface facing the electrode group of the current collecting component, damage to the electrode group can be prevented and battery performance can be ensured. The effect that can be obtained.

  Embodiments of a cylindrical lithium ion secondary battery to which the present invention is applied will be described below with reference to the drawings.

(Constitution)
As shown in FIG. 1, the cylindrical lithium ion secondary battery 13 according to the present embodiment has a hollow and resin-made shaft core in a spiral shape through a separator so that the strip-like positive and negative electrode plates do not directly contact each other. A rotated electrode group 3 is provided. The electrode group 3 is made of a nickel-plated steel plate and accommodated in a bottomed cylindrical battery can 11.

  On the upper end surface of the electrode group 3, an aluminum-made ring-shaped positive electrode current collection ring (current collection component) 4 for collecting the potential from the positive electrode plate is disposed so as to face the end surface. The positive electrode current collecting ring 4 is fixed to the upper end portion of the shaft core. A plurality of positive electrode current collectors led out from one side of the positive electrode plate are provided on the outer peripheral surface of the flange that integrally projects from the periphery of the positive electrode current collector ring 4, that is, on the side peripheral surface that intersects the surface facing the electrode group 3. The ends of the tabs 6 are collected. On the outside of the collected positive electrode current collecting tab 6, a strip-like positive electrode contact plate 5 made of aluminum is disposed so as to face the outer peripheral surface of the flange portion of the positive electrode current collecting ring 4. In other words, the positive electrode abutting plate 5 is disposed on the outer peripheral surface of the flange portion of the positive electrode current collecting ring 4 over almost the entire circumference. At this time, it arrange | positions so that the both ends of the positive electrode application plate 5 may not overlap. The positive electrode abutting plate 5 is joined to the outer peripheral surface of the flange portion of the positive electrode current collecting ring 4 with the laser beam irradiated in a substantially orthogonal direction, that is, in a substantially horizontal direction, with the axis being in the vertical direction. . Therefore, the end portion of the positive electrode current collecting tab 6 is sandwiched and joined between the outer peripheral surface of the flange portion of the positive electrode current collecting ring 4 and the inner peripheral surface of the positive electrode contact plate 5. A disc-shaped upper lid 1 serving as a positive electrode external terminal is disposed on the upper side of the positive electrode current collecting ring 4. The upper lid 1 is formed by combining a lid cap having a cylindrical projection projecting upward at a substantially central portion and a dish-shaped lid case (diaphragm) made of aluminum alloy and projecting downward (electrode group 3 side). However, it may further have a cleavage valve that cleaves at a constant internal pressure. Both ends of a belt-like positive electrode lead 2 made of aluminum are connected to the lower surface of the upper lid 1 and the upper surface of the central portion of the positive electrode current collecting ring 4, and the upper lid 1 and the positive electrode plate are electrically connected.

  On the other hand, a ring-shaped negative electrode current collector ring (current collector component) 7 made of copper for collecting the potential from the negative electrode plate is disposed on the lower end face of the electrode group 3 so as to face the end face. . The outer peripheral surface of the lower end portion of the shaft core is fixed to the central portion of the negative electrode current collecting ring 7. On the outer peripheral surface of the negative electrode current collector ring 7, that is, on the side peripheral surface intersecting the surface facing the electrode group 3, end portions of a plurality of negative electrode current collector tabs 8 led out from one side of the negative electrode plate are collected. Yes. Similar to the positive electrode application plate 5, the collected negative electrode current collection tabs 8 are arranged over the entire circumference so that both ends of the copper negative electrode application plate 9 do not overlap each other. Similarly to the positive electrode contact plate 5, the negative electrode contact plate 9 is bonded to the outer peripheral surface of the negative electrode current collecting ring 7 with the laser beam irradiated in a substantially orthogonal direction over the entire periphery. That is, the end of the negative electrode current collecting tab 8 is sandwiched and joined between the outer peripheral surface of the negative electrode current collecting ring 7 and the inner peripheral surface of the negative electrode contact plate 9. A negative electrode lead plate 10 made of nickel is bonded to the lower surface of the negative electrode current collecting ring 7. The central portion of the negative electrode lead plate 10 is joined and fixed to the inner bottom surface of the battery can 11 by resistance welding, and the battery can 11 serving also as the negative electrode external terminal and the negative electrode plate are electrically connected.

The positive electrode plate constituting the electrode group 3 is a strip-shaped aluminum foil having a thickness of 20 μm, and a mixture containing a positive electrode active material is applied substantially uniformly on both surfaces. As the mixture, lithium manganate (LiMn ₂ O ₄ ), which is a lithium transition metal double oxide as a positive electrode active material, scaly graphite as a conductive material, and polyvinylidene fluoride as a binder (hereinafter abbreviated as PVDF). And are blended. A non-coating portion of the positive electrode mixture is formed at one end portion in the longitudinal direction of the aluminum foil. This non-coated portion is cut out in a comb shape (rectangular shape), and the positive electrode current collecting tab 6 is formed in the remaining portion of the cutout. On the other hand, the negative electrode plate is substantially uniformly coated with a negative electrode mixture containing amorphous carbon powder of a negative electrode active material on both sides of a strip-like copper foil having a thickness of 10 μm. An uncoated portion of the mixture is formed. A negative electrode current collecting tab 8 is formed in this non-coated portion in the same manner as the positive electrode plate. For the separator, a microporous polyethylene film having a band shape and a thickness of 40 μm is used. The electrode group 3 is wound through a separator so that the positive electrode plate and the negative electrode plate are not in direct contact with each other. In the electrode group 3, the positive electrode current collecting tab 6 and the negative electrode current collecting tab 8 are arranged on opposite sides of the electrode group 3, and are led out in a direction substantially orthogonal to the end face of the electrode group 3.

The upper lid 1 is caulked and fixed to the upper portion of the battery can 11 via an insulating and heat resistant EPDM resin gasket 12, and the lithium ion secondary battery 13 is sealed. Further, a non-aqueous electrolyte solution (not shown) is injected into the battery can 11. The non-aqueous electrolyte is obtained by dissolving 1 mol / liter of lithium hexafluorophosphate (LiPF ₆ ) as a lithium salt in a mixed solvent of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 1: 1: 1. Is used.

(Battery manufacturing)
The lithium ion secondary battery 13 includes a preparation step in which a positive and negative electrode plate is produced, and a positive electrode current collecting tab 6 and a negative electrode current collecting tab 8 are respectively formed on the positive and negative electrode plates, and the positive and negative electrode plates are wound through a separator. A winding step for manufacturing the electrode 3, a bonding step for bonding the positive and negative electrode current collecting tabs to the positive and negative electrode current collecting rings, an assembly step for housing the electrode group 3 in the battery can 11 and completing the lithium ion secondary battery 13; Manufactured by.

  In the preparation step, a positive electrode mixture is prepared by mixing lithium manganate powder, conductive graphite flakes, and binder PVDF in a mass ratio of 85: 10: 5. Using N-methylpyrrolidone (hereinafter abbreviated as NMP) as a viscosity adjusting solvent, the positive electrode mixture is kneaded substantially uniformly to prepare a mixture slurry. A mixture slurry is applied to both sides of a strip-shaped aluminum foil. At this time, an uncoated portion of slurry is formed at one end portion in the longitudinal direction of the aluminum foil. The non-coated portion is cut out in a comb shape, and the positive electrode current collecting tab 6 is formed at the remaining portion of the cutout. Then, it dries and presses and produces a positive electrode plate. On the other hand, an amorphous carbon powder as a negative electrode active material and PVDF as a binder are mixed at a mass ratio of 90:10 to prepare a negative electrode mixture. A negative electrode mixture is kneaded substantially uniformly using NMP to prepare a mixture slurry. A mixture slurry is applied to both sides of a strip-shaped copper foil, dried, and pressed to prepare a negative electrode plate. In the same manner as the positive electrode plate, the uncoated portion is cut out in a comb shape, and the negative electrode current collecting tab 8 is formed from the remaining portion of the cutout.

  In the winding step, the winding start end portions of the two separators are fixed to the shaft core by heat welding or the like. The positive and negative electrode plates are wound around the shaft core through the separator so that the positive electrode current collecting tab 6 and the negative electrode current collecting tab 8 are opposite to each other of the electrode group 3. After winding the positive and negative electrode plates and the separator having a desired length, the positive and negative electrode plates and the separator are cut. The edge part of the cut | disconnected separator is fixed with a tape etc., and the electrode group 3 is produced.

  In the joining step, first, the positive electrode current collecting ring 4 is fixed to the upper end portion of the shaft core so as to face the upper end surface of the electrode group 3. The ends of the positive electrode current collecting tab 6 are collected on the outer peripheral surface of the heel portion of the positive electrode current collecting ring 4, and the positive electrode abutting plate 5 is disposed on the outer peripheral surface of the heel portion of the positive electrode current collecting ring 4 over the entire circumference. At this time, it arrange | positions so that the both ends of the positive electrode abutting plate 5 may not overlap (overlapping will not be formed). In a state where the shaft core is in the vertical direction, the outer peripheral surface of the collar portion of the positive electrode current collecting ring 4 is irradiated with laser light in a substantially orthogonal direction, and both ends of the positive electrode abutting plate 5 are sequentially welded with spots, and then the positive electrode abutting plate Weld around the entire circumference of 5. Accordingly, when the positive electrode backing plate 5, the positive electrode current collecting tab 6 and the positive electrode current collecting ring 4 are welded, the laser is irradiated in a substantially horizontal direction from the outside of the outer peripheral surface. Similarly, the end portions of the negative electrode current collecting tab 8 are gathered on the outer peripheral surface of the negative electrode current collecting ring 7 and are arranged over substantially the entire circumference so that both end portions of the negative electrode contact plate 9 do not overlap. After irradiating the outer peripheral surface of the negative electrode current collecting ring 7 with laser light in a substantially orthogonal direction, that is, in a substantially horizontal direction, and welding both ends of the negative electrode abutting plate 9 with spots in order, the entire circumference of the negative electrode abutting plate 9 is applied. Join.

  In the assembly process, the lithium ion secondary battery 13 is assembled using the electrode group 3 to which the positive and negative electrode current collecting parts and the like are welded. First, the negative electrode lead 10 is joined to the lower surface of the negative electrode current collecting ring 7 by welding. After the electrode group 3 is accommodated in the battery can 11, a welding jig is inserted into the hollow portion of the shaft core, and the negative electrode lead 10 is joined to the inner bottom surface of the battery can 11 by resistance welding. Both end portions of the positive electrode lead 2 are welded to the lower surface of the upper lid 1 and the upper surface of the central portion of the positive electrode current collecting ring 4. A stepping process for forming a stepped portion for placing the upper lid 1 on the upper side of the electrode group 3 of the battery can 11 is performed, and after pouring a non-aqueous electrolyte, the upper lid 1 is placed on the stepped portion, and the battery can 11 And the upper lid 1 are caulked through the gasket 12 to complete the assembly of the lithium ion secondary battery 13.

  Next, examples of the lithium ion secondary battery 13 manufactured according to the present embodiment will be described. A comparative example produced for comparison will also be described. In order to simplify the description, in the following examples, the materials of the negative electrode current collector ring 7 and the negative electrode contact plate 9 and the laser output during welding are changed. The lithium ion secondary battery 13 was produced in the same manner as each example.

(Example 1)
In the battery of Example 1, as shown in Table 1 below, the negative electrode current collecting ring 7 and the negative electrode contact plate 9 were both made of copper (Cu). The distance between both ends of the positive electrode plate 5 and the negative plate 9 was set to 1 mm. The laser output during welding of the negative electrode current collector ring 7, the negative electrode current collector tab 8, and the negative electrode contact plate 9 was set to 2000 W, and a lithium ion secondary battery 13 was produced.

(Example 2 to Example 7)
As shown in Table 1, in the batteries of Examples 2 to 7, lithium ions were used in the same manner as in Example 1 except that the materials of the negative electrode current collecting ring 7 and the negative electrode contact plate 9 and the laser output during welding were changed. A secondary battery 13 was produced. In the battery of Example 2, the material of the negative electrode current collecting ring 7 was copper, the material of the negative electrode contact plate 9 was nickel (Ni), and the laser output was 1200 W. In the battery of Example 3, the material of the negative electrode current collecting ring 7 was an alloy having a mass ratio of copper and nickel of 1: 1, the material of the negative electrode backing plate 9 was nickel, and the laser output was 1200 W. In the battery of Example 4, the negative electrode current collector ring 7 was made of a clad material (multilayer body) having a mass ratio of copper and nickel of 1: 1, the negative electrode backing plate 9 was made of nickel, and the laser output was 1200 W. In the battery of Example 5, the negative electrode current collecting ring 7 and the negative electrode contact plate 9 were both made of nickel, and the laser output was 1000 W. In the battery of Example 6, the negative electrode current collecting ring 7 was made of copper, the negative electrode backing plate 9 was made of an alloy having a mass ratio of copper and nickel of 1: 1, and the laser output was 1200 W. In the battery of Example 7, the negative electrode current collecting ring 7 was made of copper, the negative electrode contact plate 9 was made of a clad material having a mass ratio of copper and nickel of 1: 1, and the laser output was 1200 W.

(Example 8)
As shown in Table 1, in the battery of Example 8, a lithium ion secondary battery 13 was produced in the same manner as in Example 1 except that the negative electrode backing plate 9 was not used.

Example 9
As shown in Table 1, in the battery of Example 9, the lithium ion secondary plate was the same as in Example 1 except that the negative electrode backing plate 9 was arranged and laser-welded so that the overlap between both ends was formed to 5 mm. A battery 13 was produced.

(Comparative Example 1)
As shown in Table 1, in the battery of Comparative Example 1, the negative electrode backing plate was not used, and the laser beam was irradiated in a direction along the side circumferential surface intersecting the surface facing the electrode group of the negative electrode current collecting ring 7. A lithium ion secondary battery was produced in the same manner as in Example 1 except that welding was performed.

(Evaluation)
Thirty batteries of each example and comparative example were produced. At this time, the welded state of the negative electrode current collector ring 7, the negative electrode current collector tab 8, and the negative electrode contact plate 9 was evaluated for the batteries of the respective examples and comparative examples. As for the welding state, laser penetration (penetration of negative electrode current collecting ring 7 and negative electrode current collecting tab 8 by laser light) and welding state where neither welding pits occurred, laser penetration without electrode group 3 damage (damage) Alternatively, the welded state in which the weld pit was generated was evaluated in three stages: ◯, and the welded state in which the electrode group 3 was damaged was evaluated in three levels. The evaluation results are shown in Table 1.

  As shown in Table 1, in the batteries of Examples 1 to 7, neither laser penetration nor weld pits occurred. In the battery of Example 8, although laser penetration occurred, laser welding was performed substantially orthogonally to the outer peripheral surface of the negative electrode current collecting ring 7, so that no damage to the electrode group 3 was observed. The difference between the batteries of Example 1 and Example 8 is only the presence or absence of the copper negative electrode backing plate 9. Therefore, in the battery of Example 8, since the negative electrode contact plate 9 was not used, it is considered that laser penetration occurred at a place where the negative electrode current collecting tabs 8 overlapped with each other. In the battery of Example 9, weld pits occurred. The only difference between the batteries of Example 1 and Example 9 is the presence or absence of overlapping of both end portions of the negative electrode backing plate 9. Therefore, in the battery of Example 9, since both ends of the negative electrode contact plate 9 were overlapped and laser-welded, a gap was formed between the outer peripheral surface of the negative electrode current collecting ring 7 and the inner peripheral surface of the negative electrode contact plate 9. Therefore, it is considered that weld pits occurred. On the other hand, since the battery of Comparative Example 1 did not use the negative electrode backing plate, laser penetration occurred similarly to the battery of Example 8. Moreover, since the laser was irradiated in the direction along the side peripheral surface crossing the surface facing the electrode group of the negative electrode current collector ring, that is, the direction in which the electrode group was arranged, the electrode group was damaged.

(Action etc.)
Next, the operation of the lithium ion secondary battery 13 of this embodiment will be described. Both the positive and negative current collecting tabs are joined by laser welding in the same manner. However, since both of them exhibit the same action, hereinafter, the negative electrode current collecting tab 8, the negative electrode current collecting ring 7, and the negative electrode contact plate 9 will be described.

  In the lithium ion secondary battery 13 of the present embodiment, the negative electrode current collection tab 8 is formed of the negative electrode current collection tab 8 by a laser beam irradiated in a substantially horizontal direction on a side circumferential surface that intersects the surface facing the electrode group 3 of the negative electrode current collection ring 7. The electric ring 7 and the negative electrode contact plate 9 are sandwiched and joined. For this reason, since the laser beam is not irradiated in the direction in which the electrode group 3 is disposed, damage to the electrode group 3 due to laser welding can be prevented, and the battery performance of the lithium ion secondary battery 13 can be ensured.

  In the lithium ion secondary battery 13 of the present embodiment, the negative electrode current collecting tab 8 is sandwiched and joined between the outer peripheral surface of the negative electrode current collecting ring 7 and the inner peripheral surface of the negative electrode contact plate 9. For this reason, even if the overlap of the negative electrode current collection tab 8 occurs, as shown in Example 1 and Example 8, the adhesion degree of the negative electrode backing plate 9, the negative electrode current collection tab 8, and the negative electrode current collection ring 7 is maintained. Therefore, welding can be performed reliably without causing laser penetration to the negative electrode current collecting ring 7.

  Furthermore, in the lithium ion secondary battery 13 of the present embodiment, the negative electrode contact plate 9 is arranged and welded to the outer peripheral surface of the negative electrode current collecting ring 7 so that the overlapping of both ends of the negative electrode contact plate 9 is not formed. Yes. Therefore, as shown in Example 1 and Example 9, a gap is formed between the outer peripheral surface of the negative electrode current collecting ring 7 and the inner peripheral surface of the negative electrode contact plate 9 at both ends of the negative electrode contact plate 9. In addition, since poor welding such as welding pits is suppressed, the bondability of the negative electrode current collector ring 7, the negative electrode current collector tab 8, and the negative electrode contact plate 9 can be improved.

  Furthermore, in the lithium ion secondary battery 13 of the present embodiment, when the negative electrode contact plate 9 is joined to the outer peripheral surface of the negative electrode current collecting ring 7, both ends of the negative electrode contact plate 9 are first welded with spots. For this reason, the negative electrode contact plate 9 is disposed so as to face the outer peripheral surface of the negative electrode current collector ring 7. Thus, when laser welding is performed over the entire circumference of the negative electrode contact plate 9, the negative electrode current collection tab 8 can be held between the negative electrode contact plate 9 and the negative electrode current collection ring 7 without detachment, and laser welding is easy. Can be joined.

  Furthermore, in the lithium ion secondary battery 13 of the present embodiment, the outer peripheral surface of the negative electrode current collecting ring 7 is welded by laser irradiation in a substantially orthogonal direction. When the laser beam penetrates the negative electrode current collecting ring 7, the trace remains on the inner peripheral surface of the negative electrode current collecting ring 7 on the back side of the laser irradiation portion. For this reason, the presence or absence of laser penetration can be easily determined by observing the inner peripheral surface of the negative electrode current collecting ring 7. That is, it is possible to reduce the occurrence of battery failure by easily determining a defect due to laser welding before battery assembly.

  Conventionally, in a cylindrical wound lithium ion secondary battery, a strip-like positive and negative electrode plate having current collecting tabs formed at equal intervals is wound in a cross-sectional spiral shape. When the ends of the are collected, the overlap is sparse. In this case, when welding the current collecting tab and the current collecting component by irradiating a laser with a constant output in the direction along the current collecting component, if the laser output is increased so that the portion where the overlap is dense can be welded, the overlap will occur. There is a possibility that the heat input energy becomes excessive in a sparse part, and the laser light penetrates the current collecting tab and the current collecting component. For this reason, battery performance will be impaired. On the other hand, if the laser output is sufficient to weld a portion where the overlap is sparse, welding is insufficient at the portion where the overlap is dense. The present embodiment is a lithium ion battery 13 that can solve these problems.

  In the embodiment, the laser for welding is not particularly mentioned, but the present invention is not limited to the type of laser, the oscillation type, or the number of irradiations. Examples of laser types to which the present invention can be applied include YAG lasers and fiber lasers. Alternatively, a plurality of laser beams may be irradiated to join the positive and negative current collecting tabs to the positive and negative current collecting rings.

  In the present embodiment, an example is shown in which welding is performed with a laser beam that is irradiated in a substantially horizontal direction on a side circumferential surface that intersects the surface facing the electrode group 3 of the positive and negative current collecting rings. It is not limited to. That is, the present invention can be applied even if there is a slight difference in the irradiation angle from the horizontal direction unless the direction causes damage to the electrode group 3 due to laser penetration. Such an angle from the horizontal direction varies depending on the battery and size.

  Furthermore, in this embodiment, although the ring-shaped thing was illustrated as a positive / negative current collection component to which a positive / negative current collection tab is joined, this invention is not limited to this. For example, you may make it join a positive / negative current collection tab to a side peripheral surface using a disk-shaped current collection component.

  Furthermore, in the present embodiment, an example in which the belt-like positive and negative electrode contact plates are arranged over substantially the entire circumference so as not to overlap both ends on the outer peripheral surface of the positive and negative electrode current collecting ring is shown, but the present invention is limited to this. Is not to be done. For example, a plurality of contact plates may be used and arranged to face the outer peripheral surface of the positive and negative current collecting rings so that adjacent contact plates do not overlap each other.

  Furthermore, in this embodiment, although copper was illustrated as a material of the negative electrode current collection ring 7 and the negative electrode contact plate 9, this invention is not limited to this. For example, a negative electrode current collecting tab 8 made of copper and a nickel-plated battery can 11 also serving as a negative electrode external terminal can be reliably bonded to each other, and a material having high electrical conductivity, for example, copper, nickel, copper It is preferable to use an alloy of nickel and nickel or a multilayer body of copper and nickel.

  Further, in the present embodiment, an example is shown in which laser welding is performed over the entire circumference after spot welding at two locations on both ends of the positive and negative electrode contact plates, but the present invention is not limited to this. For example, some points may be further welded with spots and then joined over the entire circumference.

  Furthermore, in the present embodiment, lithium manganate is shown as the lithium-containing composite oxide of the positive electrode active material, but the present invention is not limited to this. For example, using a lithium-containing composite oxide having a different composition in which a part of manganese or lithium in a crystal is substituted or doped with other elements such as Fe, Co, Ni, Cr, Al, Mg, etc. Also good. Further, the crystal structure is not particularly limited, and may be, for example, a spinel crystal structure or a layered crystal structure. In the present embodiment, scaly graphite is exemplified as the positive electrode conductive material, but the present invention is not limited to this. Other materials having electron conductivity may be used, and in particular, a conductive material may not be used.

  Furthermore, in this embodiment, although amorphous carbon was illustrated as a negative electrode active material, this invention is not limited to this. For example, graphite-based carbon materials such as natural graphite, artificial graphite, and vapor grown carbon fiber can be used.

  Furthermore, in the present embodiment, a relatively large lithium ion secondary battery used for a power source for an electric vehicle has been exemplified, but the lithium ion secondary battery according to the present invention has a battery capacity, size, shape, etc. It is not limited. The battery to which the present invention can be applied may be other than a battery having a structure in which the upper lid is caulked and fixed to the battery can described above. As an example of such a structure, a battery in a state where positive and negative external terminals penetrate the battery lid and are pressed through the shaft core in the battery container can be mentioned.

  The present invention contributes to the manufacture and sale of lithium ion secondary batteries in order to provide a lithium ion secondary battery and a method for producing the same that can ensure battery performance, and thus has industrial applicability.

It is sectional drawing of the cylindrical lithium ion secondary battery of embodiment to which this invention is applied.

Explanation of symbols

3 Electrode group 4 Positive current collector ring (current collector component)
5 Positive electrode contact plate 6 Positive electrode current collecting tab 7 Negative electrode current collecting ring (current collecting component)
8 Negative electrode current collecting tab 9 Negative electrode pad 13 Cylindrical lithium ion secondary battery (lithium ion secondary battery)

Claims (5)

  Lithium ion secondary comprising positive and negative electrode plates each having an electrode group wound through a separator, and positive and negative electrode current collecting tabs respectively led out from one side of the positive and negative electrode plates and arranged on opposite sides of the electrode group In the battery, at least one of the positive electrode current collecting tab and the negative electrode current collecting tab has a substantially horizontal direction on a side circumferential surface intersecting with a surface facing the electrode group of a current collecting component disposed to face an end surface of the electrode group. A lithium ion secondary battery, which is bonded with a laser beam irradiated on the surface.   2. The lithium ion according to claim 1, wherein at least one of the positive electrode current collecting tab and the negative electrode current collecting tab is sandwiched and joined between a side peripheral surface of the current collecting component and a metal backing plate. Secondary battery.   3. The lithium ion secondary battery according to claim 2, wherein the contact plate is disposed opposite to a side peripheral surface of the current collecting component so that the overlapping of both ends of the plate is not formed.   3. The current collecting component to which the negative electrode current collecting tab is bonded and the contact plate are made of copper, nickel, an alloy of copper and nickel, or a multilayer body of copper and nickel, respectively. Or the lithium ion secondary battery of Claim 3.   2. The method of manufacturing a lithium ion secondary battery according to claim 1, wherein the metal contact plate is disposed so as to face the side peripheral surface of the current collecting component so that the overlapping of both ends of the plate is not formed. Then, after welding both end portions of the backing plate with spots, they are joined over the entire circumference of the backing plate.

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