JP2017107709A - Battery manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery manufacturing method which can laser-weld a connection part of a collector to a foil exposed part of an electrode plate at uniform welding strength regardless of the place to prevent a keyhole from penetrating through the collector.SOLUTION: In the battery manufacturing method, in a butting process for butting a plurality of foil exposed parts 21m of an electrode plate 21 to a collecting plate (a collector) 50x to be welded including a recessed groove 53 so that the foil exposed parts 21m overlap with each other and the foil exposed parts 21m stride across the recessed groove 53 and in a welding process for welding the foil exposed parts 21m to a connection part 50 by scanning a rear groove part 55 in a groove extending direction while irradiating laser beam LB to the part, a pair of keyholes 50h whose top part 50hs are positioned in the connection part to be welded are formed at positions across the rear groove part 55 by the laser beam LB, and a range from a site 57 between the pair of keyholes 50h to the opposing face 50a is melted.SELECTED DRAWING: Figure 9

Description

  The present invention is formed by abutting and welding a foil exposed portion of a current collector foil exposed from the electrode plate to a plate-like connecting portion of the current collector in a form in which a plurality of foil exposed portions overlap in the thickness direction. The present invention relates to a battery manufacturing method.

  A battery having a so-called tabless structure in which an electrode plate (positive electrode plate or negative electrode plate) and a current collector (positive electrode current collector or negative electrode current collector) are directly connected without a current collecting tab is known. That is, in a battery in which the current collector foil exposed from the electrode plate is exposed to a plate-shaped connection portion of the current collector and welded with a plurality of foil exposed portions overlapping in the thickness direction. is there.

  For example, Patent Document 1 discloses such a battery (see FIGS. 3 and 4 of Patent Document 1). The battery of Patent Document 1 includes a cylindrical electrode group (electrode body) in which a positive electrode plate and a negative electrode plate are wound through a porous insulating layer. In this battery, the positive electrode current collector exposed portion (positive electrode foil exposed portion) of the positive electrode plate is abutted against the disc-shaped positive electrode current collector terminal plate (positive electrode current collector) on one side in the axial direction of the electrode group. Welding. Also, on the other side of the electrode group in the axial direction, the negative electrode current collector exposed portion (negative electrode foil exposed portion) of the negative electrode plate is abutted against the disc-shaped negative electrode current collector terminal plate (negative electrode current collector) and welded. doing.

JP 2011-170972 A

  However, when the foil exposed portion of the electrode plate is abutted against the connecting portion of the current collector and both are welded by laser welding, the following problems may occur. That is, when the connecting portion of the current collector is sufficiently melted from the back surface to the facing surface by laser light, a large amount of molten metal is formed. Then, in a certain portion of the gap between the exposed foil portions adjacent to each other in the thickness direction, a lot of molten metal is sucked up by a capillary phenomenon. On the other hand, in a portion adjacent to the portion, since the molten metal is insufficient, the connection between the connecting portion of the current collector and the foil exposed portion of the electrode plate is not sufficient. In this way, non-uniform bonding is present in which there are strong and weak bonding strength between the connecting portion of the current collector and the exposed foil portion.

  Further, when the output of the laser is increased so that the connection portion of the current collector is sufficiently melted from the back surface to the opposing surface, the keyhole formed by the laser light may penetrate the connection portion of the current collector. Then, the spatter is scattered from the opposing surface to the electrode plate, or the through hole is formed and the laser beam reaches the electrode plate, so that the material such as the resin binder constituting the active material layer is deteriorated. May occur. On the other hand, if the laser output is suppressed in order to prevent the keyhole from penetrating the current collector connection, the connection does not melt sufficiently to the opposing surface, and the current collector connection and the electrode plate foil The exposed part may not be welded.

  The present invention has been made in view of the present situation, and can connect the collector connection portion and the foil exposed portion of the electrode plate with laser welding with uniform bonding strength regardless of the location, and the keyhole can collect the current. It aims at providing the manufacturing method of the battery which can prevent penetrating the connection part of a body.

  One aspect of the present invention for solving the above-described problems is that one or a plurality of electrode plates including a current collector foil includes a foil exposed portion in which both main surfaces of the current collector foil are exposed in the thickness direction. A plurality of the foil exposed portions in the thickness direction overlap the connecting portion of the current collector having a plate-like connecting portion including the opposing facing surface and the back surface of the opposing surface, and project from the facing surface side. A method of manufacturing a battery formed by contact and welding, wherein the battery is a plate including the opposing surface and the back surface, and has a pre-welding assembly including a pre-welding connection portion including a concave groove provided on the opposing surface and extending in the groove extending direction. The foil exposed portions of the one or more electrode plates overlap the connecting portion before welding of the electric body, the plurality of foil exposed portions overlap in the thickness direction, and the foil exposed portions respectively have the concave grooves. The striking process of striking from the opposite surface side to the straddling form and the connection part before welding A welding step of scanning the groove back portion on the back side of the concave groove in the groove extending direction while irradiating laser light from the back surface side and welding the plurality of exposed foil portions to the connection portions, respectively. In the welding step, a pair of laser beams that extend from the back surface toward the facing surface at a position sandwiching the groove back portion of the pre-welding connection portion and whose top portion is located in the pre-welding connection portion. And a part including the groove back part between the pair of key holes in the pre-weld connection part is melted from the back surface to the facing surface.

According to the battery manufacturing method described above, the groove back portion of the pre-welding connecting portion of the current collector before welding is thinned by the amount of the concave groove, so that only the amount of the concave groove during laser welding is provided. The amount of molten metal can be reduced. For this reason, a large amount of molten metal is produced because no concave groove is provided, and the capillary phenomenon occurs non-uniformly, and the amount of molten metal sucked into the gap between the exposed foil portions adjacent in the thickness direction becomes non-uniform. Can be suppressed. Therefore, the connection part of the current collector and the foil exposed part of the electrode plate can be joined with a uniform strength regardless of the location.
Furthermore, in the welding process, as described above, laser welding is performed so that the top portions of the pair of keyholes sandwiching the groove back portion are positioned in the connection portion before welding. For this reason, it is possible to prevent the keyhole from penetrating through the pre-weld connecting portion and spattering from the opposing surface to the electrode plate, or the through hole to be opened and the laser beam to reach the electrode plate.

  Further, in the battery manufacturing method described above, the current collector may be a battery manufacturing method made of copper.

  Since molten copper has a higher surface tension than molten aluminum or the like, a capillary phenomenon tends to occur non-uniformly, and the amount of molten copper sucked into the gap between the exposed foil portions tends to be non-uniform. However, as described above, by providing a groove in the current collector before welding, the amount of molten copper can be reduced, so that non-uniform capillary action is suppressed and sucked into the gap between the exposed foil parts. It can suppress that the quantity of the molten copper produced becomes non-uniform | heterogenous. Therefore, although the current collector is made of copper, the connection portion of the current collector and the foil exposed portion of the electrode plate can be joined with uniform strength regardless of the location.

It is a longitudinal cross-sectional view of the battery which concerns on embodiment. It is a perspective view of the electrode body which concerns on embodiment. It is an expanded view of an electrode body which concerns on embodiment and shows the state which mutually accumulated the positive electrode plate and the negative electrode plate through the separator. It is the elements on larger scale which expanded the junction part of the positive electrode current collector plate (or negative electrode current collector plate) and the positive electrode foil exposure part (or negative electrode foil exposure part of a negative electrode plate) of the battery which concerns on embodiment. . It is the top view seen from the opposing surface side of the positive electrode current collector plate before welding which concerns on embodiment (or negative electrode current collector plate before welding). It is AA sectional drawing in FIG. 5 of the positive electrode current collector plate before welding (or negative electrode current collector plate before welding) which concerns on embodiment. It is explanatory drawing which concerns on embodiment and shows the state which faced the positive electrode foil exposed part (or negative electrode foil exposed part of a negative electrode plate) of a positive electrode plate to the positive electrode current collector plate (or negative electrode current collector plate before welding) before welding. It is explanatory drawing which shows the beam pattern (1st beam pattern) of the laser beam which concerns on embodiment. It is explanatory drawing which shows the relationship between the beam pattern (1st beam pattern) of the laser beam to irradiate, and the molten state of the irradiated positive electrode current collector plate before welding (or negative electrode current collector plate before welding) concerning embodiment. . The partial expanded sectional view which expanded the junction part of the positive electrode current collector plate (or negative electrode current collector plate) and the positive electrode foil exposure part (or negative electrode foil exposure part of a negative electrode plate) concerning a comparative example 2,4,6. It is. It is explanatory drawing which shows the beam pattern (2nd beam pattern) of the laser beam which concerns on the comparative examples 3 and 4. FIG. It is explanatory drawing which concerns on the comparative example 4, and shows the relationship between the beam pattern (2nd beam pattern) of the laser beam to irradiate, and the molten state of the irradiated positive electrode current collector plate before welding.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a longitudinal sectional view of a battery 1 according to this embodiment. 2 and 3 are a perspective view and a developed view of the electrode body 20 constituting the battery 1. 4, in the battery 1, the positive electrode current collector plate (positive electrode current collector) 50 or the negative electrode current collector plate (negative electrode current collector) 60, the positive electrode foil exposed portion 21 m of the positive electrode plate 21, or the negative electrode plate 31. The partial expanded sectional view of a junction part with negative electrode foil exposed part 31m is shown.
The battery 1 is a cylindrical lithium ion secondary battery mounted on a vehicle such as a hybrid vehicle or an electric vehicle, or a battery-operated device such as a hammer drill. The battery 1 includes a battery case 10, an electrode body 20 accommodated in the battery case 10, a positive current collector plate 50 and a negative current collector plate 60 joined to the electrode body 20. In addition, a non-aqueous electrolyte 19 is accommodated in the battery case 10, and a part thereof is impregnated in the electrode body 20.

  Among these, the battery case 10 is cylindrical and made of metal (in this embodiment, aluminum). The battery case 10 has a bottomed cylindrical main body member 11 whose one side in the axial direction (upper in FIG. 1) is open and whose other side in the axial direction (lower in FIG. 1) is closed, It is comprised from the disk-shaped cover member 13 which obstruct | occludes the opening part 11h of the main body member 11. FIG. Among these, the lid member 13 is caulked and fixed to the opening 11 h of the main body member 11 via a ring-shaped seal member 15 made of an insulating resin. The lid member 13 is electrically connected to the positive electrode current collector plate 50 via the lead member 17 as will be described later, and also serves as the positive electrode terminal of the battery 1. On the other hand, the main body member 11 is connected to the negative electrode current collector plate 60 as will be described later, and also serves as the negative electrode terminal of the battery 1.

  Next, the electrode body 20 will be described (see FIGS. 1 to 4). In this electrode body 20, a belt-like positive electrode plate 21 and a belt-like negative electrode plate 31 are overlapped with each other via a pair of belt-like separators 41 and 41 (see FIG. 3), and are wound in a cylindrical shape around an axis AX. (See FIG. 2).

  The positive electrode plate 21 is formed by forming the positive electrode active material layers 23 and 23 in a band shape on a region extending in the longitudinal direction and part of the main surface 22a and 22a of the positive electrode current collector foil 22 made of a band-shaped aluminum foil. It is provided. The positive electrode active material layer 23 includes a positive electrode active material, a conductive material (conductive aid), and a binder. Further, one end of the positive electrode plate 21 in the width direction has no positive electrode active material layer 23 in the thickness direction BH (the direction orthogonal to the paper surface in FIG. 3, see FIG. 4), and the positive electrode collector in the thickness direction BH. The main surface 22a of the electric foil 22 is a positive foil exposed portion 21m where the main surfaces 22a are exposed. A part of the positive electrode plate 21 in the width direction (a part of the positive electrode foil exposed portion 21m) extends from the negative electrode plate 31 and the separators 41 and 41 to the one side AS (upward in FIGS. 1 to 4) in the axial direction AH. A plurality of positive foil exposed portions 21m overlap in the direction BH and protrude in a spiral shape. These positive electrode foil exposed portions 21m are connected to and conductive with the positive electrode current collector plate 50 while being in contact with the positive electrode current collector plate 50 described later (see FIGS. 1 and 4).

The negative electrode plate 31 has strips of negative electrode active material layers 33 and 33 formed on a part of the width direction and extending in the longitudinal direction of both main surfaces 32a and 32a of the negative electrode current collector foil 32 made of a strip-shaped copper foil. It is provided. The negative electrode active material layer 33 includes a negative electrode active material, a binder, and a thickener. One end of the negative electrode plate 31 in the width direction has no negative electrode active material layer 33 in the thickness direction BH (the direction orthogonal to the paper surface in FIG. 3, see FIG. 4), and the negative electrode current collector foil in the thickness direction BH. The two main surfaces 32a and 32a of 32 are exposed negative electrode foil exposed portions 31m. A part of the negative electrode plate 31 in the width direction (a part of the negative electrode foil exposed portion 31m) extends from the positive electrode plate 21 and the separators 41 and 41 to the other side AT in the axial direction AH (in FIGS. , Upward), a plurality of negative electrode foil exposed portions 31m overlap in the thickness direction BH and protrude in a spiral shape. These negative electrode foil exposed portions 31m are connected to and conductive with the negative electrode current collector plate 60 in a state of abutting against a negative electrode current collector plate 60 described later (see FIGS. 1 and 4).
Separator 41 consists of a resin-made porous membrane, and makes a strip shape and a film form.

The positive electrode current collector plate 50 has a disk shape having an opposing surface 50a facing the electrode body 20 (positive electrode plate 21) and a back surface 50b thereof, and is made of metal (in this embodiment, aluminum) (see FIGS. 1 and 4). ). In the present embodiment, the entire positive electrode current collector plate 50 corresponds to the “plate-shaped connecting portion including the opposing surface and the back surface” described above.
A plurality of positive electrode foil exposed portions 21m, which are overlapped in the thickness direction BH, of the positive electrode plate 21 of the electrode body 20 are abutted on the facing surface 50a side of the positive electrode current collector plate 50. The positive electrode current collector plate 50 and the positive electrode foil exposed portion 21m are joined together via a melt-solidified portion 51 that is solidified after the portion is once melted. On the other hand, the above-described lead member 17 is joined to the back surface 50 b side of the positive electrode current collector plate 50. The lead member 17 is joined to the lid member 13 of the battery case 10 on the other side.

The negative electrode current collector plate 60 has a disk shape having a facing surface 60a facing the electrode body 20 (negative electrode plate 31) and a back surface 60b thereof, and is made of metal (copper in this embodiment). In the present embodiment, the entire negative electrode current collector plate 60 corresponds to the “plate-shaped connecting portion including the opposing surface and the back surface” described above.
A plurality of negative electrode foil exposed portions 31 m that are overlapped in the thickness direction BH among the negative electrode plates 31 of the electrode body 20 are abutted against the opposing surface 60 a side of the negative electrode current collector plate 60. The negative electrode current collector plate 60 and the negative electrode foil exposed portion 31m are joined together via a melt-solidified portion 61 that is solidified after the portion is once melted. On the other hand, the back surface 60 b side of the negative electrode current collector plate 60 is joined to the bottom 11 t of the main body member 11 of the battery case 10.

Next, a method for manufacturing the battery 1 will be described (see FIGS. 5 to 9). First, the positive electrode active material layers 23 and 23 are provided in a band shape on a region extending in the longitudinal direction in a part of the width direction of both main surfaces 22a and 22a of the positive electrode current collector foil 22 made of a band-shaped aluminum foil. The positive electrode plate 21 having the positive electrode foil exposed portion 21m is formed at one end in the width direction of the positive electrode plate 21.
Separately, negative electrode active material layers 33, 33 are provided in a strip shape on a region extending in the longitudinal direction and part of the width direction of both main surfaces 32 a, 32 a of the negative electrode current collector foil 32 made of a strip-shaped copper foil. Then, the negative electrode plate 31 having the negative electrode foil exposed portion 31m is formed at one end in the width direction of the negative electrode plate 31.
Next, the positive electrode plate 21 and the negative electrode plate 31 are overlapped with each other via a pair of separators 41 and 41 (see FIG. 3), and wound around the axis AX using a winding core to form a cylindrical wound electrode. Form body 20 (see FIG. 2).

  Next, a pre-weld positive electrode current collector plate (pre-weld current collector) 50x made of aluminum is prepared (see FIGS. 5 and 6). The pre-weld positive electrode current collector plate 50x has a disk shape with a thickness Ta = 0.60 mm including the opposing surface 50a and the back surface 50b. Four opposing surfaces 50a of the positive current collector plate 50x before welding extend in the radial direction from the center 50g of the positive current collector plate 50x before welding to the peripheral edge 50f of the positive current collector plate 50x before welding (extend in the groove extending direction FH). A concave groove 53 is formed every 90 degrees. The width Wa of each concave groove 53 is preferably 0.20 to 1.00 mm, and in this embodiment, Wa = 0.50 mm. Further, the depth Ha of each concave groove 53 is preferably 0.10 to 0.50 mm, and Ha = 0.15 mm in this embodiment. In addition, the thickness Tc (see FIG. 9) of the groove back portion 55 on the back side of the groove 53 in the positive electrode current collector plate 50x before welding is Tc = 0.45 mm. In the present embodiment, the entire pre-welding positive electrode current collector plate 50x corresponds to the aforementioned “pre-weld connection portion including a concave surface and a plate shape including a facing surface and a back surface”.

  Next, in the “butting step”, the end of one side AS in the axial direction AH of the electrode body 20 is pre-welded so that the axis AX of the electrode body 20 passes through the center 50g of the positive current collector plate 50x before welding. It abuts on the positive electrode current collector plate 50x from the facing surface 50a side (see FIG. 7). As a result, a plurality of positive foil exposed portions 21m that overlap each other in the thickness direction BH of the positive electrode plate 21 of the electrode body 20 straddle the concave grooves 53, and the positive foil exposed portions 21m face the positive current collector plate 50x before welding. It can be abutted from the 50a side.

  Next, in the “welding process”, scanning is performed in the groove extending direction FH while irradiating the laser beam LB from the back surface 50b side to the groove back portion 55 on the back side of the groove 53 of the positive electrode current collector plate 50x before welding. Then, the plurality of positive foil exposed portions 21m are respectively welded to the positive current collector 50x (positive current collector 50) before welding (see FIGS. 8, 9, and 4). In this welding process, the laser beam LB extends from the back surface 50b toward the facing surface 50a at a position sandwiching the groove back portion 55 in the positive electrode current collector plate 50x before welding, and the top portion 50hs has a positive electrode current collector plate 50x before welding. A pair of keyholes 50h, 50h located inside is formed. At the same time, the laser beam LB melts the portion 57 including the groove back portion 55 between the pair of keyholes 50h, 50h in the pre-welding positive electrode current collector plate 50x from the back surface 50b to the facing surface 50a.

Specifically, welding is performed with a laser beam LB having a DOE (diffractive optics, diffractive optical element) beam pattern shown in FIGS. That is, this DOE beam pattern has a spot diameter of 40 μm, and two peaks (peak P1 and peak P2) having a high energy density arranged with an interval Ca = (width Wa + 0.20 of the groove 53) = 0.70 mm. ) And a spot diameter Da including these peaks P1 and P2 = (width Wa + 0.30 of the concave groove 53) = 0.80 mm and a peak P3 having a low energy density. The power densities of the peaks P1 and P2 are preferably 1.0 × 10 ^{6 to} 1.0 × 10 ⁸ W / cm ² , respectively, and in this embodiment, 1.0 × 10 ⁷ W / cm ² . In addition, the power density of the peak P3 is preferably 1.0 × 10 ^{4 to} 1.0 × 10 ⁶ W / cm ^2, and in this embodiment, 1.0 × 10 ⁵ W / cm ² .

By using the laser beam LB having such a beam pattern, the opposite surface from the back surface 50b to the position where the groove back portion 55 is sandwiched in the positive current collector plate 50x before welding by the peaks P1 and P2 having high energy density. A pair of keyholes 50h, 50h extending toward 50a and having the top portion 50hs positioned in the positive current collector plate 50x before welding can be formed. At the same time, the portion 57 between the pair of keyholes 50h, 50h of the positive current collector plate 50x before welding can be melted from the back surface 50b to the facing surface 50a by the peak P3 having a low energy density and a large spot diameter Da. .
Through this welding process, the positive electrode current collector plate 50 and the positive electrode foil exposed portion 21 m of the positive electrode plate 21 are joined via the melt-solidified portion 51. In addition, the angle α formed between the outer peripheral surface of the melt-solidified portion 51 located on the back surface 50b side of the concave groove 53 and the facing surface 50a of the positive electrode current collector plate 50 is 60 degrees or more (FIG. 9). reference).

  Next, a pre-weld negative electrode current collector plate (pre-weld current collector) 60x made of copper is prepared (see FIGS. 5 and 6). The pre-welding negative electrode current collector plate 60x has a disk shape with a thickness Tb = 0.60 mm including the opposing surface 60a and the back surface 60b. On the opposing surface 60a of the negative electrode current collector plate 60x before welding, four pieces (in the groove extending direction FH) extend in the radial direction from the center 60g of the negative electrode current collector plate 60x before welding to the peripheral edge 60f of the negative electrode current collector plate 60x before welding. A concave groove 63 is formed every 90 degrees. The width Wb of each concave groove 63 is preferably 0.20 to 1.00 mm, as in the case of the positive electrode. In this embodiment, Wb = 0.50 mm. The depth Hb of each concave groove 63 is preferably 0.10 to 0.50 mm, and in this embodiment, Hb = 0.15 mm. In addition, the thickness Td of the groove back portion 65 on the back side of the groove 63 in the pre-welding negative electrode current collector plate 60x is Td = 0.45 mm. In addition, in this embodiment, the whole negative electrode current collector plate 60x before welding corresponds to the above-described “plate-like shape including a facing surface and a back surface, and a connection portion before welding including a concave groove”.

  Next, in the “abutting step”, the end of the other side AT in the axial direction AH of the electrode body 20 is set to the position before welding so that the axis AX of the electrode body 20 passes through the center 60g of the negative electrode current collector plate 60x before welding. It abuts against the negative electrode current collector plate 60x from the facing surface 60a side (see FIG. 7). As a result, the negative electrode foil exposed portions 31m, which overlap each other in the thickness direction BH among the negative electrode plates 31 of the electrode body 20, straddle the concave grooves 63, and the negative electrode foil exposed portions 31m face the negative electrode current collector plate 60x before welding. It can be abutted from the 60a side.

  Next, in the “welding process”, the groove back portion 65 on the back side of the concave groove 63 in the negative electrode current collector plate 60x before welding is scanned in the groove extending direction FH while irradiating the laser beam LB from the back surface 60b side. Then, the plurality of negative electrode foil exposed portions 31m are each welded to the pre-welding negative electrode current collector plate 60x (negative electrode current collector plate 60) (see FIGS. 8, 9, and 4). In this welding process, the laser beam LB extends from the back surface 60b toward the facing surface 60a at a position sandwiching the groove back portion 65 of the negative electrode current collector plate 60x before welding, and the top portion 60hs has a negative electrode current collector plate 60x before welding. A pair of keyholes 60h, 60h located inside is formed. At the same time, the laser beam LB is used to melt the portion 67 including the groove back portion 65 between the pair of keyholes 60h and 60h from the back surface 60b to the facing surface 60a.

Specifically, as in the case of the positive electrode, welding is performed with the laser beam LB having the DOE beam pattern shown in FIGS. That is, as in the case of the positive electrode, this DOE beam pattern has two high energy densities arranged with a spot diameter of 40 μm and a distance Cb = (width Wb + 0.20 of the concave groove 63) = 0.70 mm. A peak (peak P1 and peak P2) and a spot diameter Db including these peaks P1 and P2 = (width Wb + 0.30 of the concave groove 63) = 0.80 mm and a peak P3 having a low energy density. The power densities of the peaks P1 and P2 are each preferably 1.0 × 10 ^{6 to} 1.0 × 10 ⁸ W / cm ^2, and in this embodiment, 1.0 × 10 ⁷ W / cm ² . . In addition, the power density of the peak P3 is preferably 1.0 × 10 ^{4 to} 1.0 × 10 ⁶ W / cm ^2, and in this embodiment, 1.0 × 10 ⁵ W / cm ² .

By using the laser beam LB having such a beam pattern, the opposite surface from the back surface 60b to the position where the groove back portion 65 is sandwiched in the negative current collector plate 60x before welding by the peaks P1 and P2 having high energy density. A pair of keyholes 60h, 60h extending toward 60a and having a top portion 60hs located in the negative electrode current collector plate 60x before welding can be formed. At the same time, the peak P3 having a low energy density and a large spot diameter Db can melt the portion 67 between the pair of keyholes 60h and 60h in the pre-welding negative electrode current collector plate 60x from the back surface 60b to the facing surface 60a. .
Through this welding process, the negative electrode current collector plate 60 and the negative electrode foil exposed portion 31 m of the negative electrode plate 31 are joined via the melt-solidified portion 61. In addition, an angle β formed between the outer peripheral surface of the melt-solidified portion 61 located on the back surface 60b side of the concave groove 63 and the facing surface 60a of the negative electrode current collector plate 60 is 60 degrees or more (FIG. 9). reference).

  Next, the lead member 17 and the lid member 13 are prepared, and one end side of the lead member 17 is welded to the back surface 50 b of the positive electrode current collector plate 50 and the other end side of the lead member 17 is welded to the lid member 13. Next, the main body member 11 of the battery case 10 is prepared, and the electrode body 20 in which the positive electrode current collector plate 50 and the negative electrode current collector plate 60 are joined is inserted therein. Thereafter, the negative electrode current collector plate 60 is welded to the bottom portion 11 t of the main body member 11. Next, the nonaqueous electrolyte 19 is injected into the main body member 11, and then the lid member 13 is crimped and fixed via the seal member 15 to close the opening 11 h of the main body member 11. Thereafter, the battery is subjected to initial charging and various inspections. Thus, the battery 1 is completed.

(Examples and Comparative Examples)
Subsequently, the result of the test conducted in order to verify the effect of this invention is demonstrated. As shown in Table 1 below, the positive electrode plate of the positive electrode current collector plate (or negative electrode current collector plate) and the electrode body 20 is changed by changing the presence or absence of the groove, the width of the groove, the DOE beam pattern, and the laser output. 21 positive electrode foil exposed portion 21m (or negative electrode foil exposed portion 31m of negative electrode plate 31) was laser welded.

Specifically, in Example 1, a concave groove having a width Wa = 0.20 mm is formed on the positive electrode current collector plate before welding, and a DOE beam pattern similar to that in the embodiment shown in FIG. The laser beam was welded at a laser output of 860 W according to Table 1 (referred to as “first pattern” in Table 1). Other than that, it was the same as the embodiment.
Example 2 is the same as that of the above-mentioned embodiment. That is, a concave groove having a width Wa = 0.50 mm was formed on the positive electrode current collector plate before welding, and laser welding was performed with a laser output of 1200 W using the first beam pattern.
In Example 3, a concave groove having a width Wa = 1.00 mm was formed in the positive electrode current collector plate before welding, and laser welding was performed at a laser output of 1760 W using the first beam pattern. Other than that, it was the same as the embodiment.

On the other hand, in Comparative Example 1, laser welding was performed with a laser output of 1200 W using the first beam pattern shown in FIG. Other than that, it was the same as the embodiment.
In Comparative Example 2, laser welding was performed with a laser output of 1400 W using the first beam pattern without providing a groove in the positive current collector plate before welding. Other than that, it was the same as the embodiment.
In Comparative Example 3, the positive electrode current collector plate before welding is not provided with a concave groove, and is based on the DOE beam pattern shown in FIG. 11 (this is referred to as a second beam pattern. Table 1 describes “second pattern”). Laser welding was performed at a laser output of 300 W. This DOE beam pattern is composed of only two peaks (peak P4 and peak P5) having a spot diameter of 40 μm and an interval Cc = 0.70 mm. Other than that, it was the same as the embodiment.
In Comparative Example 4, laser welding was performed with a laser output of 1200 W using the second beam pattern without providing a concave groove in the positive electrode current collector plate before welding. Other than that, it was the same as the embodiment.

Moreover, in Example 4, a concave groove with Wb = width 0.20 mm was formed in the negative electrode current collector plate before welding, and laser welding was performed with a laser output of 1360 W using the first beam pattern. Other than that, it was the same as the embodiment.
Example 5 is the same as that of the above-mentioned embodiment. That is, a concave groove having a width Wb = 0.50 mm was formed on the negative electrode current collector plate before welding, and laser welding was performed with a laser output of 1900 W using the first beam pattern.
In Example 6, a concave groove having a width Wb = 1.00 mm was formed on the negative electrode current collector plate before welding, and laser welding was performed with a laser output of 2790 W using the first beam pattern. Other than that, it was the same as the embodiment.

On the other hand, in Comparative Example 5, laser welding was performed with a laser output of 1900 W using the first beam pattern without providing a groove on the negative electrode current collector plate before welding. Other than that, it was the same as the embodiment.
In Comparative Example 6, laser welding was performed with a laser output of 2100 W using the first beam pattern without providing a groove on the negative electrode current collector plate before welding. Other than that, it was the same as the embodiment.

  About each of Examples 1-6 and Comparative Examples 1-6, the position of the top part of the keyhole formed at the time of laser welding was investigated. As shown in the lower part of FIG. 9, the one in which the top of the keyhole was located inside the positive current collector plate before welding (or the negative current collector plate before welding) was defined as “inside the current collector plate”. On the other hand, as shown in the lower part of FIG. 12, what penetrated the top part of the keyhole without staying in the pre-welding positive electrode current collector plate (or negative electrode current collector plate before welding) was defined as “penetration”. The results are shown in Table 1.

  Moreover, about each of Examples 1-6 and Comparative Examples 1-6, the generation | occurrence | production number (pieces / mm) of the spatter | spatter which scattered from the opposing surface of the positive electrode current collector plate before welding (or negative electrode current collector plate before welding) was measured with a microscope. Was measured visually. The results are shown in Table 1.

  Moreover, about each of Examples 1-6 and Comparative Examples 1-6, the positive electrode current collector plate (or negative electrode current collector plate) and the positive electrode foil exposed portion 21m of the positive electrode plate 21 (or the negative electrode foil exposed portion 31m of the negative electrode plate 31). The joint state was visually observed. A sample in which the positive electrode current collector plate and the positive electrode foil exposed portion 21m and the like were appropriately joined was defined as “good”. On the other hand, the case where the positive electrode current collector plate or the like and the positive electrode foil exposed portion 21m or the like were not joined was defined as “non-joined”. Moreover, although the positive electrode current collector plate and the positive electrode foil exposed portion 21m and the like are joined, as shown in FIG.

  As can be seen from Table 1, in Examples 1 to 3 in which a concave groove was provided in the positive electrode current collector plate before welding and laser welding was performed using the first beam pattern shown in FIG. Was located in the positive current collector plate before welding, no spatter was generated from the facing surface, and the joining state of the positive current collector plate and the positive foil exposed portion 21m was good. On the other hand, in Comparative Examples 1 to 4 in which the positive electrode current collector plate before welding was not provided with a groove, the top of the keyhole penetrates the positive electrode current collector plate before welding, spatter is generated from the opposite surface, The joining state of the plate and the positive electrode foil exposed portion 21m was “non-joined” or “non-uniform”.

  The reason is considered as follows. In Examples 1 to 3, the groove back portion of the positive electrode current collector plate before welding has a thickness Tc of 0.15 mm and Tc = 0.45 mm corresponding to the amount of the concave groove. The amount of molten aluminum can be reduced by that amount. For this reason, since a large amount of molten aluminum is not formed because the concave groove is not provided, the capillary phenomenon is unevenly generated, and the amount of molten aluminum sucked up in the gap between the positive electrode foil exposed portions 21m can be suppressed from becoming uneven. Therefore, the positive electrode current collector plate and the positive electrode foil exposed portion 21m can be uniformly bonded regardless of the place. In addition, since the tops of the pair of keyholes sandwiching the groove back portion are located in the positive current collector plate before welding, the keyhole penetrates the positive current collector plate before welding and spatter is generated from the facing surface. It is thought that we were able to prevent.

On the other hand, in Comparative Example 1, the positive electrode current collector plate before welding was not opposed to the positive electrode current collector plate before welding because the laser output was too low for the thick plate thickness (0.60 mm). Does not melt enough. For this reason, the positive electrode current collector plate and the positive electrode foil exposed portion 21m cannot be joined. Further, since the laser output is low, the tops of the pair of keyholes are located in the positive current collector plate before welding, so it is considered that no spatter occurred from the facing surface.
On the other hand, in Comparative Example 2, since the laser output was increased in order to sufficiently melt the positive electrode current collector plate before welding up to the opposing surface, the pair of keyholes as shown in the lower part of FIG. It is thought that spatter occurred from the opposing surface through the plate. Further, in Comparative Example 2, since the groove was not provided and the plate thickness was thick, a large amount of molten aluminum was produced, and the capillary phenomenon was unevenly generated, and the amount of molten aluminum sucked up in the gap between the positive electrode foil exposed portions 21m was reduced. It becomes uneven. For this reason, as shown in FIG. 10, it is considered that the joining of the positive electrode current collector plate 150 and the positive electrode foil exposed portion 21 m via the melt-solidified portion 151 becomes uneven depending on the location.

Further, in Comparative Example 3 using the second beam pattern instead of the first beam pattern, the plate thickness is not provided in the positive electrode current collector plate before welding, but the laser output is too low. The positive electrode current collector plate before welding does not melt sufficiently from the back surface to the facing surface. For this reason, the positive electrode current collector plate and the positive electrode foil exposed portion 21m cannot be joined. Further, since the laser output is low, the tops of the pair of keyholes are located in the positive current collector plate before welding, so it is considered that no spatter occurred from the facing surface.
On the other hand, in Comparative Example 4 using the second beam pattern, the laser output was increased in order to sufficiently melt and melt the positive electrode current collector plate 150x before welding up to the opposing surface. It is considered that the tops of the keyholes 150h and 150h penetrated the positive current collector plate 150x before welding and spatter was generated from the facing surface. Further, in Comparative Example 4, as in Comparative Example 2, a large amount of molten aluminum is formed, and the capillary phenomenon occurs non-uniformly, and the amount of molten aluminum sucked up in the gaps between the positive electrode foil exposed portions 21m becomes non-uniform. . For this reason, it is considered that the joining of the positive electrode current collector plate 150 and the positive electrode foil exposed portion 21m via the melt-solidified portion 151 is uneven depending on the location (see FIG. 10).

  Next, in Examples 4 to 6 in which the negative electrode current collector plate before welding was provided with a concave groove and laser welding was performed using the first beam pattern shown in FIG. 8, the top of the keyhole was the negative electrode before welding. It was located in the current collector plate, no spatter was generated from the facing surface, and the bonding state between the negative electrode current collector plate and the negative electrode foil exposed portion 31m was good. On the other hand, in Comparative Examples 5 and 6 where the negative electrode current collector plate before welding was not provided with a groove, the top of the keyhole penetrates the negative electrode current collector plate before welding, spattering occurred from the opposing surface, The bonding state between the electric plate and the negative electrode foil exposed portion 31m was “non-bonded” or “non-uniform”.

  The reason is considered as follows. As in the case of the positive electrode (Examples 1 to 3), in Examples 4 to 6, the groove back portion of the negative electrode current collector plate before welding has a thickness Td of 0.15 mm and Td = 0. Since it is 45 mm, the amount of molten copper can be reduced by the amount of the concave groove during laser welding. For this reason, it is possible to suppress a large amount of molten copper from being formed because the concave groove is not provided, and the capillary phenomenon to occur non-uniformly, and the amount of molten copper sucked into the gap between the negative electrode foil exposed portions 31m to be non-uniform. Therefore, the negative electrode current collector plate and the negative electrode foil exposed portion 31m can be uniformly joined regardless of the place. In addition, since the tops of the pair of keyholes sandwiching the groove back portion are located in the negative electrode current collector plate before welding, the keyhole penetrates the negative electrode current collector plate before welding and spatter is generated from the facing surface. It is thought that we were able to prevent.

On the other hand, in Comparative Example 5, the negative electrode current collector plate before welding was opposed to the negative electrode current collector plate before welding because the negative electrode current collector plate before welding had a thick plate thickness (0.60 mm), but the laser output was too low. Does not melt enough. For this reason, the negative electrode current collector plate and the negative electrode foil exposed portion 31m cannot be joined. In addition, since the laser output is low, the tops of the pair of keyholes are located in the negative electrode current collector plate before welding, so it is considered that no spatter occurred from the facing surface.
On the other hand, in Comparative Example 6, since the laser output was increased to sufficiently melt the negative electrode current collector plate before welding to the opposing surface, the pair of keyholes penetrated the negative electrode current collector plate before welding from the opposing surface. It is thought that spatter occurred. Further, in Comparative Example 6, since the groove was not provided and the plate thickness was thick, a large amount of molten copper was formed, and the capillary phenomenon was unevenly generated, and the amount of molten copper sucked up in the gap between the negative electrode foil exposed portions 31m was reduced. It becomes uneven. For this reason, as shown in FIG. 10, it is considered that the joining of the negative electrode current collector plate 160 and the negative electrode foil exposed portion 31m via the melt-solidified portion 161 is uneven depending on the location.

  As described above, in the manufacturing method of the battery 1 of the present embodiment, the groove back portion 55 of the pre-weld positive electrode current collector plate 50x has a thickness Tc that is reduced by the amount of the concave groove 53. The amount of molten aluminum can be reduced by the amount of the groove 53 during welding. For this reason, since the concave groove 53 is not provided, a large amount of molten aluminum is formed, and the capillary phenomenon occurs non-uniformly, and the amount of molten aluminum sucked into the gap between the positive electrode foil exposed portions 21m adjacent in the thickness direction BH is non-uniform. Can be suppressed. Therefore, the positive electrode current collector plate 50 and the positive electrode foil exposed portion 21m of the positive electrode plate 21 can be joined with a uniform strength regardless of the location. Further, in the welding process, laser welding is performed so that the top portions 50hs, 50hs of the pair of keyholes 50h, 50h sandwiching the groove back portion 55 are located in the positive current collector plate 50x before welding. For this reason, the keyhole 50h penetrates the positive electrode current collector plate 50x before welding, and spatter is scattered from the facing surface 50a to the positive electrode plate 21, or a through hole is formed and the laser beam LB reaches the positive electrode plate 21. Can be prevented.

  Further, in this embodiment, the groove back portion 65 of the negative electrode current collector plate 60x before welding has a thickness Td that is reduced by the amount of the recessed groove 63, so that the molten copper is made by the amount of the recessed groove 63 during laser welding. The amount can be reduced. For this reason, since the concave groove 63 is not provided, a large amount of molten copper is formed, and the capillary phenomenon occurs nonuniformly, and the amount of molten copper sucked up in the gap between the negative electrode foil exposed portions 31m adjacent in the thickness direction BH is nonuniform. Can be suppressed. Therefore, the negative electrode current collector plate 60 and the negative electrode foil exposed portion 31m of the negative electrode plate 31 can be joined with a uniform strength regardless of the location. Further, in the welding process, laser welding is performed such that the top portions 60hs and 60hs of the pair of keyholes 60h and 60h sandwiching the groove back portion 65 are positioned in the negative electrode current collector plate 60x before welding. For this reason, the keyhole 60h penetrates the negative electrode current collector plate 60x before welding, and spatter is scattered from the facing surface 60a to the negative electrode plate 31, or a through hole is formed and the laser beam LB reaches the negative electrode plate 31. Can be prevented.

  Furthermore, in this embodiment, the negative electrode current collector plate 60 is made of copper. Since the surface tension of molten copper is stronger than that of molten aluminum or the like, a capillary phenomenon tends to occur non-uniformly, and the amount of molten copper sucked into the gap between the negative electrode foil exposed portions 31m tends to be non-uniform. However, as described above, by providing the concave groove 63 in the negative electrode current collector plate 60, it is possible to reduce the amount of molten copper. It is possible to suppress the amount of molten copper sucked up in the gap from becoming uneven. Therefore, although the negative electrode current collector plate 60 is made of copper, the negative electrode current collector plate 60 and the negative electrode foil exposed portion 31m of the negative electrode plate 31 can be joined with a uniform strength regardless of the location.

In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.
For example, in the embodiment, the cylindrical wound electrode body 20 is exemplified as the electrode body, but is not limited thereto. For example, it may be a flat wound electrode body, that is, an electrode body in which a belt-like positive electrode plate and a belt-like negative electrode plate are overlapped with each other via a pair of belt-like separators and wound around the axis. . Alternatively, a stacked electrode body, that is, an electrode body in which a plurality of positive plates and a plurality of negative plates each having a predetermined shape (for example, a rectangular shape) are alternately stacked via separators may be used.

DESCRIPTION OF SYMBOLS 1 Battery 20 Electrode body 21 Positive electrode plate 21m Positive electrode foil exposed part 22 Positive electrode collector foil 22a Main surface 23 Positive electrode active material layer 31 Negative electrode plate 31m Negative electrode foil exposed part 32 Negative electrode current collector foil 32a Main surface 33 Negative electrode active material layer 50 Positive electrode collector Electric plate (positive electrode current collector, connection part)
50x Positive current collector plate before welding (current collector before welding, connection part before welding)
50a Opposite surface 50b Back surface 50h Keyhole 50hs (Keyhole) top 51 Melt-solidified portion 53 Concave groove 55 Groove back portion 57 (including groove back portion) Site 60 Negative electrode current collector plate (Negative electrode current collector, connection portion)
60x Negative electrode current collector plate before welding (current collector before welding, connection part before welding)
60a Opposing surface 60b Back surface 60h Keyhole 60hs (Keyhole) top portion 61 Melting and solidifying portion 63 Concave groove 65 Groove back portion 67 (including groove back portion) Site BH Thickness direction FH Groove extending direction LB Laser light

Claims (1)

A foil exposed portion in which both main surfaces of the current collecting foil are exposed in the thickness direction among one or a plurality of electrode plates including the current collecting foil,
In the connection portion of the current collector having a plate-like connection portion including an opposing surface facing the electrode plate and a back surface of the opposing surface,
In the form in which the plurality of foil exposed portions overlap in the thickness direction, the battery is produced by abutting and welding from the facing surface side,
One or more of the pre-welding connection portions of the pre-welding current collector having a pre-welding connection portion including a concave groove provided on the opposing surface and extending in the groove extending direction in a plate shape including the facing surface and the back surface. The abutting step of abutting the foil exposed portion of the electrode plate from the facing surface side in a form in which the plurality of foil exposed portions overlap in the thickness direction, and each of the foil exposed portions straddles the concave groove When,
Scanning in the groove extending direction while irradiating a laser beam from the back side to the groove back part on the back side of the concave groove among the pre-welding connection parts, and welding the plurality of foil exposed parts to the connection parts respectively. A welding process to perform,
In the above welding process,
By the above laser beam,
A pair of keyholes extending from the back surface toward the facing surface at a position sandwiching the groove back portion in the pre-welding connection portion, and forming a pair of keyholes whose top portions are located in the pre-welding connection portion, and
A battery manufacturing method in which a portion including the groove back portion between the pair of keyholes in the connection portion before welding is melted from the back surface to the facing surface.

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