Battery cell and method for manufacturing the same

Abstract

To provide an elongated battery which can simultaneously achieve: suppressing a damage of an insulator on a sealing board due to laser welding; suppressing laser omission at a welded portion between a case body and the sealing board; and ensuring a welding depth.SOLUTION: A length of a sealing board in a longitudinal direction is 250 mm or more and 400 nm or less. A length of the sealing board in a traverse direction is 13 mm or more and 27 mm or less. A thickness of the sealing board is 1.4 mm or more and 2.4 mm or less. A shortest distance from a boundary between a case body and the sealing board to an insulator is 1.4 mm or more and 10 mm or less. A beam of a laser welding includes a core beam and a ring beam. An outer diameter of the core beam is 0.11 mm or more and 0.20 mm or less. An outer diameter of the ring beam is 0.48 mm or more and 0.75 mm or less. A depth of the laser welding is 0.6 mm or more and 90% of the thickness of the sealing board or less. A center of the core beam is shifted from the boundary between the case body and the sealing board by 0 mm or more and 0.25 mm or less to a case body side.SELECTED DRAWING: Figure 15

Description

Technical Field

[0001] This technology relates to battery cells and methods for manufacturing the same.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2007-207453 (Patent Document 1) discloses a method for manufacturing a rectangular sealed battery. Patent Document 1 discloses laser welding of the fitting portion between an outer can (case body) and a sealing plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a demand for a battery having a higher capacity and a higher operating voltage than conventional ones. Under such circumstances, as a battery with a new concept, battery cells having an elongated outer shape compared to the conventional ones have emerged. The inventor has studied laser welding of the outer can (case body) and the sealing plate in the above-described elongated battery cell.

[0005] In an elongated battery cell, an insulator that insulates between an electrode terminal and a sealing plate and a laser welding portion are likely to be close to each other in the short-side direction, and it is required to suppress damage to the insulator due to laser welding in this portion. Further, in an elongated battery cell, laser leakage from the fitting portion of the sealing plate is likely to occur, and thus it is necessary to effectively suppress this. Furthermore, in an elongated battery cell, in order to obtain a predetermined rigidity, it is required to secure a welding depth of a certain level or more.

[0006] Thus, when laser welding the fitting portion between the outer can (case body) and the sealing plate in an elongated battery cell, (1) To suppress damage to the insulator provided on the sealing plate. (2) Suppresses laser leakage from gaps in the mating parts. (3) Ensure sufficient welding depth. This presents a new and unprecedented challenge: achieving these three points simultaneously.

[0007] The objective of this technology is to provide a battery cell and a method for manufacturing the same that simultaneously achieve suppression of insulator damage, suppression of laser penetration at the weld between the case body and the sealing plate, and securing of welding depth. [Means for solving the problem]

[0008] This technology provides the following battery cells and methods for manufacturing them.

[0009] [1] The process comprises the steps of: housing an electrode body in a case body having a roughly rectangular parallelepiped shape with an opening; attaching an insulator and electrode terminals to a roughly rectangular sealing plate having a longitudinal and a transverse direction; providing the sealing plate with the insulator and electrode terminals attached to the opening of the case body; and sealing the opening by laser welding the case body and the sealing plate, wherein the longitudinal length of the sealing plate is 250 mm or more and 400 mm or less, the transverse length of the sealing plate is 13 mm or more and 27 mm or less, and the thickness of the sealing plate is 1.4 mm or more and 2.4 mm or less, case A method for manufacturing a battery cell, wherein the shortest distance from the boundary between the main body and the sealing plate to the insulator is 1.4 mm or more and 10 mm or less, the laser welding beam includes a core beam and a ring beam, the outer diameter of the core beam is 0.11 mm or more and 0.20 mm or less, the outer diameter of the ring beam is 0.48 mm or more and 0.75 mm or less, the laser welding depth is 0.6 mm or more and 90 percent or less of the thickness of the sealing plate, and the center of the core beam is shifted by 0 mm or more and 0.25 mm or less toward the case body from the boundary between the case body and the sealing plate.

[0010] [2] The method for manufacturing a battery cell as described in [1], wherein the output of the core beam is 700W or more and 1200W or less.

[0011] [3] The method for manufacturing a battery cell according to [1] or [2], wherein the output of the ring beam is 1750W or more and 2900W or less.

[0012] [4] A method for manufacturing a battery cell according to any one of items [1] to [3], wherein the beam scanning speed in laser welding is 180 mm / s or more and 500 mm / s or less.

[0013] [5] A battery cell comprising a case body in the shape of a roughly rectangular parallelepiped for housing an electrode body, a sealing plate in the shape of a roughly rectangular shape having a longitudinal direction and a transverse direction, an insulator and electrode terminals attached to the sealing plate, and a welded joint for joining the sealing plate and the case body, wherein the longitudinal length of the sealing plate is 250 mm or more and 400 mm or less, the transverse length of the sealing plate is 13 mm or more and 27 mm or less, the thickness of the sealing plate is 1.4 mm or more and 2.4 mm or less, the maximum width of the welded joint is 1.0 mm or more and 1.4 mm or less, the depth of the welded joint is 0.6 mm or more and 90 percent or less of the thickness of the sealing plate, and the shortest distance between the edge of the welded joint and the insulator is 0.60 mm or more and 1.05 mm or less. [Effects of the Invention]

[0014] According to this technology, when laser welding the mating portion between the battery cell case body and the sealing plate in an elongated battery cell, it is possible to simultaneously suppress damage to the insulator, suppress laser penetration at the welded portion between the case body and the sealing plate, and ensure the welding depth. [Brief explanation of the drawing]

[0015] [Figure 1] This is a perspective view of a rectangular rechargeable battery. [Figure 2] This is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] This is a plan view of the positive electrode plate that makes up the electrode body. [Figure 4] This is a plan view of the negative electrode plate that makes up the electrode body. [Figure 5] This is a plan view showing an electrode body consisting of a positive electrode plate and a negative electrode plate. [Figure 6]It is a diagram showing the connection structure between the electrode body, the positive current collector member, and the negative current collector member. [Figure 7] It is a diagram showing the attachment structure of the positive current collector member and the negative current collector member to the sealing plate. [Figure 8] It is a cross-sectional view taken along the line VIII-VIII in FIG. 7. [Figure 9] It is a cross-sectional view taken along the line IX-IX in FIG. 7. [Figure 10] It is a diagram showing the state where the sealing plate and the electrode body are connected. [Figure 11] It is a flowchart showing each step of the method for manufacturing a battery cell. [Figure 12] It is a cross-sectional view showing the periphery of the welded part between the rectangular outer package and the sealing plate. [Figure 13] It is a diagram schematically showing the laser welding process. [Figure 14] It is a diagram showing the beam used for laser welding. [Figure 15] It is a diagram for explaining the irradiation position of the beam. [Figure 16] It is a diagram showing a plurality of beams with different outer diameters. [Figure 17] It is a diagram showing the relationship between the outer diameter of the beam and the allowable gap amount. [Figure 18] It is a diagram showing the relationship between the core output of the beam and the welding depth. [Figure 19] It is a diagram showing the welding depth for each center position of the beam. [Figure 20] It is a diagram showing the results of the welding depth and insulator damage when the welding position (horizontal axis) and the core output (vertical axis) are changed. [Figure 21] It is a diagram showing a cross-sectional photograph of an example of the welded part. [Figure 22] It is a diagram for explaining the maximum width (B30) of the welded part and the shortest distance (L30) between the edge of the welded part and the insulator.

Embodiments for Carrying Out the Invention

[0016] Embodiments of this technology are described below. Note that the same or corresponding parts may be denoted by the same reference numerals, and their descriptions may not be repeated.

[0017] In the embodiments described below, when referring to the number, quantity, etc., unless otherwise specified, the scope of this technology is not necessarily limited to that number, quantity, etc. Also, in the embodiments described below, each component is not necessarily essential to this technology unless otherwise specified. Furthermore, this technology is not necessarily limited to achieving all of the effects and advantages mentioned in these embodiments.

[0018] In this specification, the terms "comprise," "include," and "have" are in open-ended form. That is, if a configuration includes one configuration, it may also include other configurations, or it may not.

[0019] Furthermore, where geometric terms and terms describing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° oblique," "coaxial," and "alongside," these terms allow for manufacturing tolerances or slight variations. Where terms describing relative positional relationships, such as "upper" and "lower," are used in this specification, these terms are used to indicate the relative positional relationship in a single state, and the relative positional relationship may be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by inverting the entire mechanism upside down).

[0020] In this specification, "battery" is not limited to lithium-ion batteries, but may include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, "electrode" may refer collectively to the positive electrode and the negative electrode. Also, "electrode plate" may refer collectively to the positive electrode plate and the negative electrode plate.

[0021] In this specification, "battery cell" can be installed in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs), etc. However, the use of "battery cell" is not limited to automotive applications.

[0022] Figure 1 is a perspective view of the prismatic secondary battery 1000. Figure 2 is a cross-sectional view taken along line II-II in Figure 1.

[0023] As shown in Figures 1 and 2, the rectangular secondary battery 1000 (battery cell) includes a battery case 100, an electrode body 200, an insulating sheet 300, a positive electrode terminal 400, a negative electrode terminal 500, a positive electrode current collector 600, a negative electrode current collector 700, and a cover member 800.

[0024] The battery case 100 consists of a rectangular casing 110 with a bottom and an opening, and a sealing plate 120 that seals the opening of the rectangular casing 110. The rectangular casing 110 and the sealing plate 120 are preferably made of metal, and preferably of aluminum or an aluminum alloy.

[0025] The sealing plate 120 is provided with an electrolyte injection hole 121. After the electrolyte is injected into the battery case 100 through the electrolyte injection hole 121, the electrolyte injection hole 121 is sealed by a sealing member 122. As the sealing member 122, for example, a blind rivet or other metal member can be used.

[0026] A gas release valve 123 is provided in the sealing plate 120. The gas release valve 123 ruptures when the pressure inside the battery case 100 exceeds a predetermined value. This causes the gas inside the battery case 100 to be released outside the battery case 100.

[0027] The electrode body 200 is housed in the battery case 100 along with the electrolyte. The electrode body 200 consists of a positive electrode plate and a negative electrode plate stacked with a separator in between. A resin insulating sheet 300 is placed between the electrode body 200 and the rectangular casing 110.

[0028] A positive electrode tab 210A and a negative electrode tab 210B are provided at the end of the electrode body 200 on the side facing the sealing plate 120.

[0029] The positive electrode tab 210A and the positive electrode terminal 400 are electrically connected via the positive electrode current collector 600. The positive electrode current collector 600 includes a first positive electrode current collector 610 and a second positive electrode current collector 620. The positive electrode current collector 600 may consist of a single component. The positive electrode current collector 600 is preferably made of metal, and more preferably of aluminum or an aluminum alloy.

[0030] The negative electrode tab 210B and the negative electrode terminal 500 are electrically connected via the negative electrode current collector 700. The negative electrode current collector 700 includes a first negative electrode current collector 710 and a second negative electrode current collector 720. The negative electrode current collector 700 may consist of a single component. The negative electrode current collector 700 is preferably made of metal, and more preferably of copper or a copper alloy.

[0031] The positive terminal 400 is fixed to the sealing plate 120 via a resin external insulating member 410. The negative terminal 500 is fixed to the sealing plate 120 via a resin external insulating member 510.

[0032] The positive terminal 400 is preferably made of metal, and more preferably of aluminum or an aluminum alloy. The negative terminal 500 is preferably made of metal, and more preferably of copper or a copper alloy. The negative terminal 500 may have a region made of copper or a copper alloy located on the inside of the battery case 100 and a region made of aluminum or an aluminum alloy located on the outside of the battery case 100.

[0033] The cover member 800 is located between the first positive electrode current collector 610 and the electrode body 200. The cover member 800 may also be provided on the negative electrode current collector side. Furthermore, the cover member 800 is not an essential component and can be omitted as appropriate.

[0034] Figure 3 is a plan view of the positive electrode plate 200A that constitutes the electrode body 200. The positive electrode plate 200A has a main body portion 220A on both sides of a positive electrode core made of rectangular aluminum foil, on which a positive electrode active material mixture layer containing a positive electrode active material (e.g., lithium nickel cobalt manganese composite oxide), a binder (e.g., polyvinylidene fluoride (PVdF)), and a conductive material (e.g., carbon material) is formed. The positive electrode core protrudes from the end of the main body portion, and this protruding positive electrode core constitutes the positive electrode tab 210A. A positive electrode protective layer 230A containing alumina particles, a binder, and a conductive material is provided in the portion of the positive electrode tab 210A adjacent to the main body portion 220A. The positive electrode protective layer 230A has an electrical resistance greater than the electrical resistance of the positive electrode active material mixture layer. The positive electrode active material mixture layer does not necessarily have to contain a conductive material. The positive electrode protective layer 230A is not necessarily provided.

[0035] Figure 4 is a plan view of the negative electrode plate 200B that constitutes the electrode body 200. The negative electrode plate 200B has a main body portion 220B on both sides of a negative electrode core made of rectangular copper foil, with negative electrode active material mixture layers formed thereon. The negative electrode core protrudes from the end of the main body portion 220B, and this protruding negative electrode core constitutes the negative electrode tab 210B.

[0036] Figure 5 is a plan view showing an electrode body 200 consisting of a positive electrode plate 200A and a negative electrode plate 200B. As shown in Figure 5, the electrode body 200 is manufactured such that the positive electrode tabs 210A of each positive electrode plate 200A and the negative electrode tabs 210B of each negative electrode plate 200B are stacked at one end. Approximately 50 positive electrode plates 200A and 50 negative electrode plates 200B are stacked together. The positive electrode plates 200A and 50 negative electrode plates 200B are stacked alternately via rectangular separators made of polyolefin. Alternatively, a long separator can be folded in a zigzag pattern.

[0037] Figure 6 shows the connection structure between the electrode body 200 and the positive electrode current collector 600 and the negative electrode current collector 700. As shown in Figure 6, the electrode body 200 is composed of a first electrode body element 201 (first stacked group) and a second electrode body element 202 (second stacked group). Separators are also placed on the outer surfaces of the first electrode body element 201 and the second electrode body element 202, respectively.

[0038] Multiple positive electrode tabs 210A of the first electrode element 201 constitute the first positive electrode tab group 211A. Multiple negative electrode tabs 210B of the first electrode element 201 constitute the first negative electrode tab group 211B. Multiple positive electrode tabs 210A of the second electrode element 202 constitute the second positive electrode tab group 212A. Multiple negative electrode tabs 210B of the second electrode element 202 constitute the second negative electrode tab group 212B.

[0039] A second positive electrode current collector 620 and a second negative electrode current collector 720 are positioned between a first electrode element 201 and a second electrode element 202. The second positive electrode current collector 620 has a first opening 620A and a second opening 620B. The first positive electrode tab group 211A and the second positive electrode tab group 212A are welded to the second positive electrode current collector 620, forming a welded connection portion 213. The first negative electrode tab group 211B and the second negative electrode tab group 212B are welded to the second negative electrode current collector 720, forming a welded connection portion 213. The welded connection portion 213 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, etc.

[0040] Figure 7 shows the mounting structure of the positive electrode current collector 600 and the negative electrode current collector 700 to the sealing plate 120. Figure 8 shows the cross section VIII-VIII in Figure 7. Figure 9 shows the cross section IX-IX in Figure 7.

[0041] As shown in Figure 7, the sealing plate 120 has a roughly rectangular shape with a longitudinal direction and a transverse direction. For example, the longitudinal length (L1) of the sealing plate 120 is approximately 250 mm to 400 mm (preferably 300 mm to 350 mm). For example, the transverse length (L2) of the sealing plate 120 is approximately 13 mm to 27 mm.

[0042] As shown in Figures 8 and 9, the sealing plate 120 is a plate-shaped member having a thickness (T). For example, the thickness (T) of the sealing plate 120 is approximately 1.4 mm to 2.4 mm.

[0043] The attachment of the positive electrode current collector 600 to the sealing plate 120 will be described with reference to Figures 7 and 8.

[0044] An external insulating member 410 made of resin is placed on the outer side of the sealing plate 120. A first positive electrode current collector 610 and an insulating member 630 made of resin (positive electrode current collector holder) are placed on the inner side of the sealing plate 120. Next, the positive electrode terminal 400 is inserted into the through hole of the external insulating member 410, the positive electrode terminal mounting hole of the sealing plate 120, the through hole of the first positive electrode current collector 610, and the through hole of the insulating member 630. Then, the crimped portion 400A located at the tip of the positive electrode terminal 400 is crimped onto the first positive electrode current collector 610. This fixes the positive electrode terminal 400, the external insulating member 410, the sealing plate 120, the first positive electrode current collector 610, and the insulating member 630. It is preferable that the crimped portions of the positive electrode terminal 400 and the first positive electrode current collector 610 be welded together by laser welding or the like. The first positive electrode current collector 610 has a counterbore hole 610A, and the crimping portion 400A is provided inside the counterbore hole 610A.

[0045] Furthermore, the second positive electrode current collector 620 is positioned on the insulating member 630 such that a portion of the second positive electrode current collector 620 overlaps with the first positive electrode current collector 610. In the first opening 620A provided in the second positive electrode current collector 620, the second positive electrode current collector 620 is welded to the first positive electrode current collector 610 by laser welding or the like.

[0046] As shown in Figure 8, the insulating member 630 has a cylindrical portion 630A that protrudes toward the electrode body 200. The cylindrical portion 630A penetrates the second opening 620B of the second positive electrode current collector 620 and defines a hole 630B that communicates with the electrolyte injection hole 121.

[0047] When attaching the positive electrode current collector 600 to the sealing plate 120, first, the first positive electrode current collector 610 is connected to the insulating member 630 on the sealing plate 120. Next, the second positive electrode current collector 620, which is connected to the electrode body 200, is attached to the first positive electrode current collector 610. At this time, the second positive electrode current collector 620 is positioned on the insulating member 630 such that a part of the second positive electrode current collector 620 overlaps with the first positive electrode current collector 610. Subsequently, the area around the first opening 620A provided in the second positive electrode current collector 620 is welded to the first positive electrode current collector 610 by laser welding or the like.

[0048] Next, the attachment of the negative electrode current collector 700 to the sealing plate 120 will be described with reference to Figures 7 and 9.

[0049] An external insulating member 510 made of resin is placed on the outer side of the sealing plate 120. A first negative electrode current collector 710 and an insulating member 730 (negative electrode current collector holder) made of resin are placed on the inner side of the sealing plate 120. Next, the negative electrode terminal 500 is inserted into the through hole of the external insulating member 510, the negative electrode terminal mounting hole of the sealing plate 120, the through hole of the first negative electrode current collector 710, and the through hole of the insulating member 730. Then, the crimped portion 500A located at the tip of the negative electrode terminal 500 is crimped onto the first negative electrode current collector 710. This fixes the negative electrode terminal 500, the external insulating member 510, the sealing plate 120, the first negative electrode current collector 710, and the insulating member 730. It is preferable that the crimped portions of the negative electrode terminal 500 and the first negative electrode current collector 710 be welded together by laser welding or the like.

[0050] Furthermore, the second negative electrode current collector 720 is positioned on the insulating member 730 such that a portion of the second negative electrode current collector 720 overlaps with the first negative electrode current collector 710. In the first opening 720A provided in the second negative electrode current collector 720, the second negative electrode current collector 720 is welded to the first negative electrode current collector 710 by laser welding or the like.

[0051] When attaching the negative electrode current collector 700 to the sealing plate 120, first, the first negative electrode current collector 710 is connected to the insulating member 730 on the sealing plate 120. Next, the second negative electrode current collector 720, which is connected to the electrode body 200, is attached to the first negative electrode current collector 710. At this time, the second negative electrode current collector 720 is positioned on the insulating member 730 such that a part of the second negative electrode current collector 720 overlaps with the first negative electrode current collector 710. Subsequently, the area around the first opening 720A provided in the second negative electrode current collector 720 is welded to the first negative electrode current collector 710 by laser welding or the like.

[0052] Figure 10 shows the state in which the sealing plate 120 and the electrode body 200 are connected. As described above, the first electrode body element 201 and the second electrode body element 202 are attached to the sealing plate 120 via the positive electrode current collector member 600 and the negative electrode current collector member 700. As a result, as shown in Figure 10, the first electrode body element 201 and the second electrode body element 202 are connected to the sealing plate 120, and the electrode body 200 is electrically connected to the positive electrode terminal 400 and the negative electrode terminal 500.

[0053] From the state shown in Figure 10, the first electrode element 201 and the second electrode element 202 are combined into one. At this time, the first positive electrode tab group 211A and the second positive electrode tab group 212A are bent in different directions from each other. The first negative electrode tab group 211B and the second negative electrode tab group 212B are bent in different directions from each other.

[0054] The first electrode element 201 and the second electrode element 202 can be bundled together using tape or the like. Alternatively, the first electrode element 201 and the second electrode element 202 can be bundled together by placing them inside an insulating sheet formed into a box or bag shape. Furthermore, the first electrode element 201 and the second electrode element 202 can be fixed together by adhesive.

[0055] The combined first electrode element 201 and second electrode element 202 are wrapped in an insulating sheet 300 and inserted into the rectangular casing 110. Subsequently, the sealing plate 120 is welded to the rectangular casing 110, sealing the opening of the rectangular casing 110 with the sealing plate 120, thereby forming a sealed battery case 100.

[0056] Subsequently, a non-aqueous electrolyte is injected into the battery case 100 through an electrolyte injection hole 121 provided in the sealing plate 120. As the non-aqueous electrolyte, for example, one containing ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) is used.

[0057] After the non-aqueous electrolyte is injected, the electrolyte injection hole 121 is sealed by the sealing member 122. The prismatic secondary battery 1000 is completed by performing the above steps.

[0058] Figure 11 is a flowchart showing each step of the manufacturing method for the prismatic secondary battery 1000. As shown in Figure 11, the manufacturing method for the prismatic secondary battery 1000 includes the steps of: housing the electrode body 200 in a roughly rectangular casing 110 (case body) having an opening (S10); attaching external insulating members 410, 510 (insulators) and positive electrode terminals 400 and negative electrode terminals 500 (electrode terminals) to a sealing plate 120 (S20); providing the sealing plate 120 with the external insulating members 410, 510, positive electrode terminals 400 and negative electrode terminals 500 attached to the opening of the prismatic casing 110 (S30); and sealing the opening by laser welding the prismatic casing 110 and the sealing plate 120 (S40).

[0059] Figure 12 is a cross-sectional view showing the area around the weld between the rectangular casing 110 and the sealing plate 120. Figure 12 shows a cross-section in the YZ plane of the area where the positive terminal 400 is located, but a similar structure is shown in the area where the negative terminal 500 is located.

[0060] Referring to Figure 12, the shortest distance (A) from the boundary (O) between the rectangular outer casing 110 and the sealing plate 120 to the outer insulating member 410 is, for example, about 1.4 mm, and preferably between 1.4 mm and 10 mm.

[0061] Here, the boundary (O) between the rectangular exterior body 110 and the sealing plate 120 corresponds to the center line of the gap when the sealing plate 120 is positioned so that the fitting gap between the rectangular exterior body 110 and the sealing plate 120 is symmetrical on both sides.

[0062] Figure 13 is a schematic diagram showing the laser welding process between the rectangular casing 110 and the sealing plate 120. As shown in Figure 13, laser welding is performed by irradiating the welding area between the rectangular casing 110 and the sealing plate 120 with a beam 20 from the irradiation device 10.

[0063] Figure 14 shows a beam 20 used in laser welding. As shown in Figure 14, the beam 20 includes a core beam 21 and a ring beam 22.

[0064] In this embodiment, the outer diameter of the core beam 21 is approximately 0.11 mm to 0.20 mm (preferably approximately 0.13 mm to 0.17 mm, and as an example, approximately 0.15 mm).

[0065] Furthermore, in this embodiment, the outer diameter of the ring beam 22 is approximately 0.48 mm to 0.75 mm (preferably approximately 0.53 mm to 0.68 mm, for example approximately 0.60 mm).

[0066] In this embodiment, when laser welding the rectangular outer casing 110 and the sealing plate 120, (1) Suppression of damage to the external insulating members 410 and 510 (2) Suppression of laser leakage from the gap in the fitting portion between the rectangular outer casing 110 and the sealing plate 120 (3) Ensuring welding depth These three points are being considered. The following explains these three points.

[0067] Figure 15 is a diagram illustrating the irradiation position of beam 20. As shown in Figure 15, in beam 20, the center of the core beam 21 is shifted by approximately 0 mm to 0.25 mm (preferably 0 mm to 0.20 mm, for example approximately 0.10 mm) towards the rectangular casing 110 from the boundary (O) between the rectangular casing 110 and the sealing plate 120.

[0068] Figure 16 shows multiple beams 20A, 20B, and 20C with different outer diameters. Figure 17 shows the relationship between the outer diameter of beam 20 (ring beam 22) and the allowable clearance.

[0069] As shown in Figure 16, the outer diameter decreases in the order of beams 20A, 20B, and 20C. A small fitting gap exists between the rectangular casing 110 and the sealing plate 120. When using beam 20C, which has a relatively smaller outer diameter, depending on the size of the fitting gap, laser penetration may occur, and the strength of the laser welding may not be sufficiently ensured, which is relatively more likely.

[0070] In other words, as shown in Figure 17, when the outer diameter of the beam 20 is relatively large, the allowable gap between the rectangular casing 110 and the sealing plate 120 is also relatively large, and when the outer diameter of the beam 20 is relatively small, the allowable gap between the rectangular casing 110 and the sealing plate 120 is also relatively small. The outer diameter of the beam 20 (ring beam 22) and the allowable gap between the rectangular casing 110 and the sealing plate 120 are roughly proportional.

[0071] In this embodiment, the laser welding depth is approximately 0.6 mm or more (preferably approximately 1.0 mm or more, for example approximately 1.2 mm). Furthermore, the laser welding depth is approximately 90 percent or less (preferably approximately 80 percent or less) of the thickness (T) of the sealing plate 120.

[0072] Figure 18 shows the relationship between the core output of beam 20 and the weld depth. Figure 19 shows the weld depth for each center position of beam 20.

[0073] In Figures 18 and 19, for "Beam A," the outer diameter of the core beam 21 is 0.11 mm and the outer diameter of the ring beam 22 is 0.45 mm; for "Beam B," the outer diameter of the core beam 21 is 0.15 mm and the outer diameter of the ring beam 22 is 0.60 mm; and for "Beam C," the outer diameter of the core beam 21 is 0.30 mm and the outer diameter of the ring beam 22 is 0.87 mm.

[0074] Furthermore, the "inner displacement [mm]" on the horizontal axis of Figure 19 represents the amount by which the center of the beam 20 has shifted from the boundary (O) between the rectangular outer casing 110 and the sealing plate 120 toward the sealing plate 120.

[0075] As shown in Figure 18, for "Beam A," "Beam B," and "Beam C," increasing the core output increases the welding depth for all of them. However, for "Beam C," which has a larger beam diameter, a larger core output is required to maintain the same welding depth.

[0076] From the standpoint of ensuring a certain welding depth, it is necessary to increase the core output. On the other hand, if the core output is too high, the external insulating members 410 and 510, which are close to the welding position, may be damaged by the beam 20. In Figure 18, damage to the external insulating members 410 and 510 was confirmed in the sample indicated by "α".

[0077] As shown in Figure 19, the welding depth tends to decrease as the center of the beam 20 shifts away from the boundary (O) between the rectangular exterior body 110 and the sealing plate 120 towards the sealing plate 120.

[0078] Based on the trends described above, it is necessary to consider the central position of beam 20, as well as the output and diameter of core beam 21 and ring beam 22.

[0079] Figure 20 shows the results of welding depth and insulator damage when the welding position (horizontal axis) and core output (vertical axis) of beam 20 are changed. In Figure 20, the results are shown using "Beam B", in which the outer diameter of the core beam 21 is 0.15 mm and the outer diameter of the ring beam 22 is 0.60 mm.

[0080] In Figure 20, from the viewpoint of ensuring a predetermined welding depth (5σ guaranteed depth), the region 1A above curve 1 (an example shown with a double circle in Figure 20) is preferable. However, the region 2A above curve 2 (an example shown with an "X" in the upper right of Figure 20) is undesirable because it is prone to damage to the external insulating members 410 and 510. The region 1B below curve 1 (an example shown with a single circle in Figure 20) can also be used, but the region 3A below curve 3 (an example shown with an "X" at the bottom of Figure 20) is undesirable because it results in a smaller welding depth.

[0081] From the above perspective, by setting the center (welding position) of the beam 20 to a position shifted approximately 0.1 mm outward from the boundary (O) between the rectangular casing 110 and the sealing plate 120, and setting the output of the core beam 21 to 1100W to 1200W, it is possible to ensure a desirable welding depth while suppressing damage to the external insulating members 410 and 510, even if a certain degree of variation (process error) occurs. By performing similar tests under different beam diameters, it is possible to determine the preferred center position of the beam 20, as well as the preferred output of the core beam 21 and the preferred diameters of the core beam 21 and ring beam 22.

[0082] In this embodiment, the preferred output of the core beam 21 is approximately 700W to 1200W (more preferably approximately 900W to 1200W, for example approximately 1100W). The preferred output of the ring beam 22 is approximately 1750W to 2900W (more preferably approximately 2200W to 2900W, for example approximately 2700W).

[0083] Furthermore, the scanning speed of the beam 20 in laser welding can be changed as appropriate, but is generally between 180 mm / s and 500 mm / s (preferably between 230 mm / s and 400 mm / s, for example around 300 mm / s).

[0084] Figure 21 is a cross-sectional photograph of an example of a laser-welded area 30. Referring to Figure 21, the welding depth (D30) at the deepest part 31 of the laser-welded area 30 corresponds to the "welding depth," and the center of the deepest part 31 corresponds to the "welding position" (center of the beam 20).

[0085] Figure 22 shows the maximum width (B30) of the laser-welded portion 30 and the shortest distance (L30) between the edge of the laser-welded portion 30 and the external insulating member 410 (insulator) in the completed prismatic secondary battery 1000.

[0086] In the prismatic secondary battery 1000 according to this embodiment, the maximum width (B30) of the laser-welded portion 30 is preferably about 1.0 mm to 1.4 mm (more preferably about 1.1 mm to 1.4 mm, for example about 1.3 mm). Also, the shortest distance between the edge of the laser-welded portion 30 and the external insulating members 410, 510 (insulators) is preferably about 0.60 mm to 1.05 mm (more preferably about 0.65 mm to 0.9 mm, for example about 0.7 mm).

[0087] While embodiments of the present technology have been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present technology is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0088] 10 Irradiation device, 20, 20A, 20B, 20C beams, 21 core beam, 22 ring beam, 30 laser welding section, 31 deepest part, 100 battery case, 110 rectangular casing, 120 sealing plate, 121 electrolyte injection hole, 122 sealing member, 123 gas discharge valve, 200 electrode body, 200A positive electrode plate, 200B negative electrode plate, 201 first electrode body element, 202 second electrode body element, 210A positive electrode tab, 210B negative electrode tab, 211A first positive electrode tab group, 211B first negative electrode tab group, 212A second positive electrode tab group, 212B second negative electrode tab group, 213 welding connection section, 220A, 220B main body section, 230A positive electrode protective layer, 300 insulating sheet, 400 Positive terminal, 400A, 500A; crimped part, 410, 510; external insulating member, 500; negative terminal, 600; positive current collector, 610; first positive current collector, 610A; counterbore hole, 620; second positive current collector, 620A, 720A; first opening, 620B; second opening, 630, 730; insulating member, 630A; cylindrical part, 630B; hole part, 700; negative current collector, 710; first negative current collector, 720; second negative current collector, 800; cover member, 1000; rectangular secondary battery.

Claims

1. A process of housing an electrode body in a case body that is roughly rectangular in shape and has an opening, A process of attaching an insulator and electrode terminals to a substantially rectangular sealing plate having a longitudinal direction and a transverse direction, A step of fitting the sealing plate, to which the insulator and the electrode terminals are attached, into the inside of the opening of the case body, The process includes a step of sealing the opening by laser welding the case body and the sealing plate, The longitudinal length of the sealing plate is 250 mm or more and 400 mm or less. The length of the sealing plate in the shorter direction is 13 mm or more and 27 mm or less. The thickness of the sealing plate is 1.4 mm or more and 2.4 mm or less. The shortest distance from the boundary between the case body and the sealing plate to the insulator is 1.4 mm or more and 10 mm or less. The laser welding beam includes a core beam and a ring beam, the outer diameter of the core beam is 0.11 mm or more and 0.20 mm or less, and the outer diameter of the ring beam is 0.48 mm or more and 0.75 mm or less. The depth of the laser welding is 0.6 mm or more, and 90 percent or less of the thickness of the sealing plate. The center of the core beam is located at a position shifted by 0.10 mm to 0.25 mm toward the case body from the boundary between the case body and the sealing plate. A method for manufacturing a battery cell, wherein the laser welding is performed so that the edge of the laser-welded portion on the case body side does not reach the outer edge of the case body.

2. The method for manufacturing a battery cell according to claim 1, wherein the output of the core beam is 700W or more and 1200W or less.

3. The method for manufacturing a battery cell according to claim 1 or claim 2, wherein the output of the ring beam is 1750W or more and 2900W or less.

4. The method for manufacturing a battery cell according to claim 1 or claim 2, wherein the scanning speed of the beam in the laser welding is 180 mm / s or more and 500 mm / s or less.

5. A case body having an opening and a substantially rectangular parallelepiped shape for housing an electrode body, A substantially rectangular sealing plate having a longitudinal direction and a transverse direction, which is fitted inside the opening and seals the opening, The insulator and electrode terminals attached to the sealing plate, The sealing plate and the case body are joined together by a welded joint, The longitudinal length of the sealing plate is 250 mm or more and 400 mm or less. The length of the sealing plate in the shorter direction is 13 mm or more and 27 mm or less. The thickness of the sealing plate is 1.4 mm or more and 2.4 mm or less. The maximum width of the welded portion is 1.0 mm or more and 1.4 mm or less. The depth of the welded portion is 0.6 mm or more, and 90 percent or less of the thickness of the sealing plate. The shortest distance between the edge of the welded portion and the insulator is 0.60 mm or more and 1.05 mm or less. The aforementioned welded portion is formed such that the edge of the welded portion on the case body side does not reach the outer edge of the case body in the battery cell.

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