JP2013127906A - Secondary battery and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit the occurence of defects due to an electrolytic solution remaining near an opening, thereby achieving high quality and high reliability of a secondary battery.SOLUTION: A secondary battery comprises: a container; a heat input part 8; and a lid. The container has a wall part provided with an opening and houses an electrode body and an electrolytic solution. The heat input part comprises portions, provided on an outer surface of the wall surface along an edge of the opening and arranged in a direction that moves away from the opening, and is provided on the wall part. The lid is fixed to the wall part overlapping with the heat input part and closes the opening. The heat input part has: first portions 8c enclosing the opening; and a second portion 8d which encloses the opening at a position close to the edge compared to the first portions, the heat input being deeper than that of the first portion in the second portion 8d.

Description

  Embodiments described herein relate generally to a secondary battery and a method for manufacturing the secondary battery.

  2. Description of the Related Art In recent years, secondary batteries represented by lithium ion batteries have been used for various purposes, mainly in-vehicle applications, and production has been steadily expanding. When manufacturing a secondary battery, a method of manufacturing a battery by enclosing the battery components in a metal case is often employed. In addition, in order to improve the space efficiency of the secondary battery, a rectangular battery case is increasingly employed rather than a conventional round case. In both cases of round and square battery cases, laser welding, which can efficiently produce a structure, has been widely used in lithium ion battery production.

In the manufacturing process of a lithium ion battery, laser welding is often used in the following three processes.
1. 1. Cap seam welding that connects the aluminum can body and the cap body. 2. Seal welding for closing the injection port for injecting the electrolyte. Component welding to connect multiple cells electrically in parallel or in series

Japanese Patent No. 3585213

  However, of the above-described processes, the second sealing welding process is known to have a high technical difficulty because the vicinity of the liquid injection port that is easily contaminated with the electrolyte must be laser welded. When welding is performed with a metal lid for sealing in a state where the electrolytic solution remains attached around the liquid injection port, a welding defect occurs due to the influence of the electrolyte or solvent contained in the electrolytic solution. Moreover, even if welding is performed after removing the electrolytic solution by suction or wiping, there may be a case where a bonding failure that appears to be caused by the electrolytic solution occurs at a certain rate.

  The secondary battery according to the embodiment includes a container, a heat input unit, and a lid. The said container has a wall part provided with opening and accommodates the electrode body and electrolyte solution. The heat input portion includes a portion provided along an edge of the opening on the outer surface of the wall portion and arranged in a direction away from the opening, and is provided on the wall portion. The lid is fixed to the wall portion in a state of being overlapped with the heat input portion, and closes the opening. The heat input section includes a first portion that surrounds the opening, and a second portion that surrounds the opening nearer the edge than the first portion and has a deeper heat input than the first portion. ing.

It is an external appearance perspective view which shows schematic structure of the secondary battery which concerns on 1st Embodiment. It is a top view which expands and shows the sealing lid periphery of the container with which the secondary battery which concerns on 1st Embodiment is provided. It is a figure which shows the outline of the cross section along the A1-A1 line | wire of FIG. 2 which concerns on 1st Embodiment. It is a top view which shows the heat input part of the secondary battery which concerns on 1st Embodiment. It is a figure which shows a part of cross section along the A1-A1 line | wire of FIG. 2 which concerns on 1st Embodiment. It is a flowchart which shows the flow of the manufacturing process of the secondary battery which concerns on 1st Embodiment. It is explanatory drawing for demonstrating the laser irradiation in the manufacturing process of the secondary battery which concerns on 1st Embodiment. It is a top view which shows the heat input part of the secondary battery which concerns on 2nd Embodiment. It is a top view which shows the heat input part of the secondary battery which concerns on the modification of 2nd Embodiment.

  Hereinafter, embodiments will be described in detail with reference to the drawings. Note that similar components are included in the following embodiments. Therefore, in the following, common reference numerals are given to those similar components, and redundant description is omitted.

(First embodiment)
As shown in FIG. 1, the secondary battery 1 according to the present embodiment includes an electrode body 2, a container 3 that houses the electrode body 2 together with an electrolytic solution, and a pair of a positive electrode terminal 4 and a negative electrode terminal 5. . Examples of the secondary battery 1 include a nonaqueous electrolyte secondary battery such as a lithium ion battery.

  The electrode body 2 is formed by winding a positive electrode sheet and a negative electrode sheet, which are power generation elements, in a spiral shape via a separator, and is housed in the container 3 together with an electrolytic solution.

  The container 3 is a flat rectangular parallelepiped exterior container, and is formed of a metal such as aluminum or an aluminum alloy, for example. The container 3 has a container body 3a having an opening at the upper end (in FIG. 1) and a rectangular plate-shaped lid 3b that closes the opening of the container body 3a. The lid 3b is attached to the container body 3a. It is welded and liquid-tight. The lid 3b is an example of a wall portion.

  The positive terminal 4 is provided at one end in the longitudinal direction of the lid 3b, and the negative terminal 5 is provided at the other end in the longitudinal direction of the lid 3b. The positive electrode terminal 4 and the negative electrode terminal 5 are connected to the positive electrode and the negative electrode of the electrode body 2, respectively, and protrude from the upper surface of the lid 3b. Further, one of the terminals, for example, the positive electrode terminal 4 is electrically connected to the lid 3 b and has the same potential as the container 3. The negative electrode terminal 5 extends through the lid 3b, and between the negative electrode terminal 5 and the lid 3b, a sealing material made of an insulating material such as synthetic resin or glass, for example, a gasket (not shown). ) Is provided. This sealing material hermetically seals between the negative electrode terminal 5 and the container 3 and is electrically insulated.

  For example, a rectangular safety valve 6 is provided at the center of the lid 3b. The safety valve 6 is formed by thinning a part of the lid 3b to about half the thickness, and a stamp is formed at the center of the upper surface of the thin part. When the gas is generated in the container 3 due to abnormality of the secondary battery 1 and the internal pressure of the container 3 rises to a predetermined value or more, the safety valve 6 is opened and releases the gas in the container 3. Reduce the internal pressure.

  Moreover, as shown in FIG.1 and FIG.2, the liquid injection port 7 is provided in the cover body 3b. The liquid injection port 7 is an example of an opening. The liquid injection port 7 is a through hole that penetrates the lid 3b in the thickness direction of the lid 3b. The liquid injection port 7 is formed in a circular shape as an example. An electrolytic solution is injected into the container 3 from the liquid injection port 7.

  Moreover, the heat input part 8 is provided in the cover body 3b, as shown in FIG. The heat input portion 8 is provided in a substantially annular shape surrounding the liquid injection port 7. The heat input portion 8 is a portion where heat is input to the lid 3b by light or the like. In the present embodiment, as an example, the heat input portion 8 is provided by irradiating the outer surface 3c of the lid 3b with laser light. The heat input portion 8 is provided around the liquid injection port 7 in a predetermined region R1 including the liquid injection port 7 on the outer surface 3c of the lid 3b. The predetermined region R <b> 1 is, for example, a circular region having a radius of about several millimeters with the center of the liquid injection port 7 as the center, and the radius is larger than the radius of the sealing lid 9.

  As shown in FIGS. 3 to 5, the heat input portion 8 has a plurality of groove portions 8 a and a plurality of penetration portions 8 b (FIG. 5) extending from the groove portions 8 a. The heat input section 8 is provided in a spiral shape surrounding the liquid injection port 7. Accordingly, the liquid injection port 7 includes a plurality of side portions 8 c that are provided along the edge 7 a of the liquid injection port 7 on the outer surface 3 c of the lid 3 b and are arranged in a direction away from the liquid injection port 7. Each side part 8c has a groove part 8a and a melted part 8b. In addition, the dashed-dotted line X in FIG. 4 has shown an example of the boundary part of the side parts 8c adjacent in the spiral direction. The groove portions 8a of the side portions 8c are connected to each other and have a spiral shape. Moreover, the penetration part 8b of each side part 8c is mutually connected, and has comprised helical form.

  As shown in FIG. 5, the heat input depth L1 of the side portion 8c located at the innermost periphery among the plurality of side portions 8c is deeper than the heat input depth L2 of the other side portions 8c. Hereinafter, the side part 8c located on the innermost periphery among the plurality of side parts 8c is also referred to as the innermost peripheral part 8d for convenience. Here, in the present embodiment, as an example, the side portion 8c located on the outer peripheral side of the innermost peripheral portion 8d corresponds to the first portion surrounding the liquid injection port 7, and the innermost peripheral portion 8d is It corresponds to a second part that surrounds the liquid injection port 7 near the edge 7a of the liquid injection port 7 from the first part and has a deeper heat input than the first part. Thus, the depth of heat input differs because the amount of heat input by the laser light per unit area of the outer surface 3c of the lid 3b when the innermost peripheral portion 8d is provided is the innermost peripheral portion 8d. This is because the amount of heat input by the laser light per unit area of the outer surface 3c when the side portion 8c located on the outer peripheral side of the outer surface 3c is provided is larger. Here, the innermost peripheral portion 8 d is a portion that is located closest to the edge 7 a of the liquid injection port 7 in the heat input portion 8. In other words, in the present embodiment, in the heat input portion 8, the second portion is located closest to the edge 7 a of the liquid injection port 7.

  As shown in FIGS. 3 and 4, the heat input section 8 is separated from the edge 7 a of the liquid injection port 7. That is, a non-irradiation region R <b> 2 that is a region where the laser beam is not irradiated exists between the heat input portion 8 and the edge 7 a of the liquid injection port 7. The non-irradiation region R2 has a substantially flat shape. In FIG. 4 and FIGS. 8 and 9 of the second embodiment to be described later, hatching is given to the non-irradiation region R2.

  As shown in FIG. 5, the distance W <b> 1 from the edge (inner edge) 8 e on the liquid inlet 7 side of the heat input portion 8 to the edge 7 a of the liquid inlet 7 is the liquid inlet 7 of the side portion 8 c in the heat input portion 8. It is preferable that the length is 0.5 to 10 times the width W2 along the direction away from the distance.

  Here, as described above, the heat input section 8 is provided by irradiating the laser beam spirally onto the predetermined region R1 around the liquid injection port 7 on the lid 3b. At this time, the laser beam with an output that melts the metal is irradiated. As shown in FIG. 4, the laser irradiation start point P1 is a position away from the edge 7a of the liquid injection port 7, the laser beam is irradiated spirally from the inside to the outside, and the laser irradiation end point P2 is a predetermined value. This is a position on the outer edge of the region R1. At this time, the starting end of the groove 8a corresponding to the laser irradiation start point P1 is initially a semicircular arc, but when the groove 8a adjacent to the start point P1 is formed, the groove 8a overlaps the start point P1, The shape of the crumbled shape has a fan-shaped arc shape shorter than the semicircular arc. On the other hand, since the end of the groove 8a corresponding to the end point P2 of laser irradiation is located on the outermost periphery, it has a semicircular arc shape unlike the start end.

  As an example, a sealing lid 9 that closes the liquid injection port 7 is fixed to the lid 3b by laser welding. The sealing lid 9 is an example of a lid. The sealing lid 9 is made of, for example, a metal such as aluminum or an aluminum alloy, and is overlapped with the heat input portion 8 (groove portion 8a) and fixed to the lid 3b. The sealing lid 9 is formed in a circular shape, for example, and has a radius larger than the radius of the liquid injection port 7 and smaller than the radius of the predetermined region R1.

  Here, the sealing lid 9 is welded to the lid 3 b on the liquid inlet 7 side of the outer edge 8 f of the heat input portion 8. The outer edge 8 f is a portion farthest from the liquid injection port 7 in the heat input portion 8. Therefore, the welding mark 10 exists on the inner peripheral side of the outer edge 8 f of the heat input portion 8. Then, the depth of heat input from the outer surface 3c to the sealing lid 9 in the welding of the sealing lid 9 and the lid body 3b, rather than the depth L1 of heat input of the innermost peripheral portion 8d from the outer surface 3c of the lid body 3b. L3 is deeper. Therefore, in this embodiment, the depth of heat input from the outer surface 9a of the sealing lid 9 in the welding of the sealing lid 9 and the lid body 3b, rather than the depth L1 of heat input from the outermost surface 3c along the innermost periphery 8d. L4 is deeper.

  Next, a method for manufacturing the secondary battery 1 will be described.

  As shown in FIG. 6, first, an electrolytic solution is injected into the container 3 from the injection port 7 using an electrolytic solution injection device (not shown) (step S1). Thereafter, the container 3 filled with the electrolyte is supplied to the laser irradiation device 20 (see FIG. 7) (step S2).

Next, the ambient atmosphere of the container 3 into which the electrolytic solution has been injected is brought into a reduced pressure state (step S3). Note that the entire container 3 or only the upper part where the sealing lid 9 is located is confined in a sealed space, that is, the chamber of the laser irradiation apparatus 20. The atmosphere of the sealed space in the chamber is reduced to 20 kPa, for example, in an N ₂ atmosphere.

  After depressurization in step S3, the laser irradiation device 20 is used to irradiate the periphery of the liquid injection port 7 of the container 3 (the above-described predetermined region R1) with laser light, and the predetermined region R1 of the outer surface 3c of the lid 3b of the container 3 The heat input part 8 is formed in (Step S4).

  Here, as illustrated in FIG. 7, the laser irradiation device 20 includes a laser irradiation unit 21 that irradiates laser light, and a control device 22 that controls the laser irradiation unit. For example, the control device 22 is a computer having a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). In the control device 22, the CPU controls the laser irradiation unit 21 in accordance with a program stored in the ROM.

  In step S4, in the laser irradiation device 20, the laser irradiation unit 21 controlled by the control device 22 irradiates an output laser beam in which the metal melts in the predetermined region R1 on the lid 3b spirally from the inside to the outside. To do. The laser irradiation unit 21 starts irradiation with laser light from a position away from the edge 7 a of the liquid injection port 7. Thereby, the helical heat input part 8 spaced apart from the edge 7a of the liquid injection port 7 is provided. The heat input portion 8 provided in this way includes a side portion 8c provided along the edge 7a of the liquid injection port 7 on the outer surface 3c of the lid 3b and arranged in a direction away from the liquid injection port 7.

  At this time, in the laser irradiation device 20, the amount of heat input by the laser light per unit area of the outer surface 3c of the lid 3b when the innermost peripheral portion 8d is provided is along the outer peripheral side of the innermost peripheral portion 8d. Laser light is irradiated so as to be larger than the amount of heat input by the laser light per unit area of the outer surface 3c when the portion 8c is provided.

  As an example, the laser irradiation apparatus 20 sets the scanning speed (linear velocity) of the laser light when providing the innermost peripheral portion 8d (second portion) along the inner peripheral portion 8d along the outer peripheral portion 8d. It is slower than the scanning speed of the laser beam when providing the (first portion). For example, the scanning speed of the laser beam when providing the side portion 8c located on the outer peripheral side of the innermost peripheral portion 8d is 5 to 20 times the scanning speed of the laser beam when the innermost peripheral portion 8d is provided. Within the range, and preferably within the range of 5 to 10 times. The magnification between the scanning speeds of the laser beams is not limited to the above value, and may be other than the above value. Moreover, the scanning speed of the laser beam when the side portion 8c located on the outer peripheral side of the innermost peripheral portion 8d is provided is, for example, in a range of 10 mm / s to 500 mm / s. The scanning speed of the laser beam is not limited to the above value, and may be other than the above value.

  As another example, the laser irradiation apparatus 20 uses the laser beam irradiation output when providing the innermost peripheral portion 8d (second portion) along the outer portion 8c (first portion) of the innermost peripheral portion 8d. Higher than the laser beam irradiation output when the portion is provided.

  Here, the laser beam irradiation output when providing the heat input section 8 in the laser irradiation apparatus 20 is, for example, in the range of 300 W to 3000 W, and when forming the side portions 8 c other than the innermost peripheral portion 8 d. The laser light irradiation output at this time is preferably in the range of 700 W to 800 W. The laser beam irradiation output is not limited to the above value, and may be other than the above value. Moreover, the wavelength of the laser beam when the laser irradiation apparatus 20 provides the heat input part 8 is in the range of 800 nm to 1300 nm as an example. The wavelength of the laser beam is not limited to the above value, and may be other than the above value.

  When the laser beam is irradiated in this manner, the electrolyte adhering around the liquid injection port 7 is evaporated and removed by heat generated when the metal is melted by the laser beam. If the attached electrolytic solution is not removed and the sealing lid 9 is laser welded to the lid 3b in a later process, welding defects such as perforations frequently occur.

  As an example, the laser irradiation apparatus 20 extracts the liquid injection port 7 from image data obtained by photographing the periphery of the liquid injection port 7 (an area including the predetermined region R1) in advance, and the extracted liquid injection port 7 is subjected to image processing. The coordinates are specified, and the laser irradiation position is corrected on the basis of the obtained coordinate values, and the laser beam of the output in which the metal melts is collected around the liquid injection port 7 and irradiated by scanning spirally. .

  As a scanning method for scanning with this laser beam, it is desirable to use a scanning method using a scanner such as a galvano scanner because the laser beam can be scanned at high speed. However, a method of rotating the work body of the container 3 or a method of moving the optical system using a moving mechanism such as a robot may be used.

  In addition, before forming the heat input part 8, you may make it absorb the electrolyte solution which overflowed around the injection hole 7 of the container 3 with an absorber. In this case, it is possible to more reliably remove the electrolytic solution adhering to the periphery of the liquid injection port 7. Further, when the upper end of the liquid injection port 7 is formed in a tapered shape, the heat input portion 8 may be formed from the tapered portion.

  Next, after the heat input part 8 is formed in step S4, the sealing lid 9 is placed on the heat input part 8 at a position where the liquid injection port 7 is closed by a mounting device (not shown) such as a robot (step S5).

  Next, the sealing lid 9 is laser-welded and fixed to the lid 3b of the container 3 in the aforementioned reduced pressure state (step S6). In step S <b> 6, the laser irradiation device 20 uses the laser irradiation unit 21 to apply the laser output for forming the heat input unit 8 on the outer surface (surface) 9 a located on the opposite side of the lid 3 b of the sealing lid 9. Laser light having an output that melts high metal (for example, about twice the laser output for forming the heat input portion 8) is irradiated in an annular shape. Thereby, a laser beam is irradiated in the annular | circular shape along the edge 7a of the injection hole 7, and the sealing lid | cover 9 is welded to the cover body 3b.

  As shown in FIG. 2, by this laser welding, a welding mark (welding portion) 10 for fixing the sealing lid 9 and the lid 3b to each other is formed in an annular shape, and the outer edge 8f of the heat input portion 8 (the outer edge of the predetermined region R1). ), That is, on the liquid injection port 7 side. At this time, the sealing lid 9 is disposed so that all of the outer edges thereof are inside the outer edge 8f of the heat input portion 8 (the outer edge of the predetermined region R1), that is, the liquid injection port 7 side.

  In the welding of the sealing lid 9 described above, when the sealing lid 9 is welded, the entire container 3 or only the upper part where the sealing lid 9 is located is confined in a sealed space when the sealing lid 9 is welded. The sealed space is made into a reduced pressure atmosphere. At this time, when the exhaust speed is high or when the ultimate vacuum is high, a large amount of electrolyte leaks from the injection port 7, and as an example, the reduced pressure atmosphere is preferably controlled in the range of 10 kPa to 30 kPa. For example, the exhaust system is controlled with a pressure of 20 kPa as a target value. Thereafter, welding is performed by scanning the laser beam on the sealing lid 9 in an annular atmosphere in a reduced pressure atmosphere as described above. The scanning method for scanning this laser beam is the same as the formation of the groove 8a described above. It is desirable to use a scanning method using a scanner such as a galvano scanner because the laser beam can be scanned at high speed. However, depending on the scanning speed, a method of rotating the work body of the container 3 or a method of moving the optical system using a moving mechanism such as a robot may be used.

  Finally, a predetermined inspection such as a shipping test is performed (step S7).

  As described above, in this embodiment, the outer surface 3c of the lid 3b is irradiated with the laser beam on the outer surface 3c of the lid 3b of the container 3 into which the electrolytic solution has been injected, along the edge 7a of the liquid injection port 7. The heat input part 8 including the side part 8d aligned in the direction away from the liquid injection port 7 is provided in the lid 3b. And the sealing lid 9 is piled up on the heat input part 8 in the position which plugs the liquid injection port 7, and the said sealing lid 9 is fixed to the cover body 3b by laser welding. Therefore, the electrolytic solution remaining around the liquid injection port 7 can be removed by evaporation by heat generated by laser irradiation when forming the heat input portion 8. And the sealing lid | cover 9 is welded to the container 3 after the removal of the electrolyte solution. As a result, the occurrence of defects caused by the electrolyte remaining in the vicinity of the injection port 7 can be suppressed to improve the quality of the injection port 7 sealing welding, and the high quality and high reliability of the secondary battery 1 can be realized. it can. In addition, the secondary battery 1 can be manufactured with a high yield.

  In the present embodiment, the amount of heat input by the laser beam per unit area of the outer surface 3c when the innermost peripheral portion 8d of the heat input portion 8 is provided is along the outer peripheral side of the innermost peripheral portion 8d. More than the amount of heat input by the laser beam per unit area of the outer surface 3c when 8c is provided. Thereby, in the heat input part 8, the depth of the heat input of the innermost peripheral part 8d becomes deeper than the depth of the heat input of the along part 8c located on the outer peripheral side of the innermost peripheral part 8d. Thereby, for example, the electrolyte remaining on the liquid injection port 7 side (for example, the non-irradiation region R2) of the innermost peripheral portion 8d can be more reliably evaporated and removed. Thereby, in this embodiment, compared with the case where the amount of heat input of the innermost peripheral part 8d is made the same as the other along part 8c, the defect generation rate due to the electrolytic solution could be reduced to 1/50.

  Moreover, in this embodiment, the heat input part 8 is separated from the edge 7a of the liquid injection port 7, and the non-irradiation region R2 exists between the heat input part 8 and the edge 7a of the liquid injection port 7. Therefore, when forming the heat input part 8, it can suppress that a laser beam enters into the container 3 from the liquid injection port 7, and it can suppress that abnormality arises in the container 3. FIG. At this time, in this embodiment, the distance W1 from the edge (inner edge) 8e on the liquid injection port 7 side of the heat input unit 8 to the edge 7a of the liquid injection port 7 is the liquid injection port of the side portion 8c in the heat input unit 8. It is preferable that the length is 0.5 to 10 times the width W2 along the direction away from 7. Thereby, when forming the heat input part 8, it can suppress more that a laser beam enters into the container 3 from the liquid injection port 7. FIG.

  In the present embodiment, as an example, the scanning speed of the laser beam when providing the side portion 8c located on the outer peripheral side of the innermost peripheral portion 8d is the laser beam scanning speed when the innermost peripheral portion 8d is provided. It is in the range of 5 to 20 times the speed, and preferably in the range of 5 to 10 times. Moreover, the scanning speed of the laser beam when the side portion 8c located on the outer peripheral side of the innermost peripheral portion 8d is provided is, for example, in a range of 10 mm / s to 500 mm / s. Thereby, the heat input part 8 can be satisfactorily formed without damaging the lid 3b, and the electrolytic solution adhering around the liquid injection port 7 can be removed. The scanning speed of the laser beam can be measured with a speed measuring device.

  Moreover, in this embodiment, the laser beam irradiation output at the time of providing the heat input part 8 in the laser irradiation apparatus 20 is in the range of 300 W to 3000 W as an example, and the side part 8 c other than the innermost peripheral part 8 d The laser beam irradiation output at the time of forming is preferably in the range of 700 W to 800 W. Thereby, the heat input part 8 can be satisfactorily formed without damaging the lid 3b, and the electrolytic solution adhering around the liquid injection port 7 can be removed. The laser beam irradiation output can be measured by a laser beam irradiation output measuring device.

  Moreover, in this embodiment, the wavelength of the laser beam when the laser irradiation apparatus 20 provides the heat input part 8 is in the range of 800 nm to 1300 nm as an example. By using a laser beam having a wavelength within the above range, the heat input portion 8 can be formed satisfactorily without damaging the lid 3b, and the electrolytic solution adhering to the periphery of the liquid injection port 7 can be removed. it can. The wavelength of the laser beam can be measured with a laser wavelength measuring device.

  In addition, since the electrolyte remaining around the liquid injection port 7 enters each groove 8a, the occurrence of an electrolyte pool spreading over a wide range is suppressed, so that the remaining electrolyte affects the laser welding in the subsequent process. Is suppressed. For this reason, it is possible to more reliably suppress the occurrence of defects due to the electrolyte remaining in the vicinity of the liquid injection port 7 and to further improve the quality of the liquid injection port 7 sealing welding.

  Further, since the laser beam is irradiated spirally along the outer edge of the liquid injection port 7 to the predetermined region R1 around the liquid injection port 7 to form the heat input unit 8, the heat input unit 8 is made relatively Since it can be formed in a short time, the manufacturing time of the secondary battery 1 can be shortened.

  Further, since the plurality of side portions 8c are sequentially formed from the inside to the outside with the liquid injection port 7 as the center, the remaining electrolytic solution is more reliably surrounded by the periphery of the liquid injection port 7 as compared with the case of sequentially forming from the outside to the inside. It becomes possible to remove from. Thereby, generation | occurrence | production of the defect resulting from the electrolyte solution which remained in the injection hole 7 vicinity can be suppressed more reliably.

  Here, when laser irradiation is performed from the inside to the outside for the predetermined region R1, a phenomenon occurs in which the electrolytic solution remaining around the liquid injection port 7 moves from the inside to the outside, It moves to a region outside the predetermined region R1, that is, a region not involved in laser welding of the sealing lid 9 to the container 3. On the other hand, when laser irradiation is performed on the predetermined region R1 from the outside to the inside, a phenomenon occurs in which the electrolytic solution remaining around the liquid injection port 7 moves from the outside to the inside. Since the laser beam gathers in the vicinity of the liquid injection port 7 in the region related to the laser welding of the sealing lid 9 with respect to 3 and forms a large droplet, the laser beam becomes difficult to act. Therefore, it is possible to remove the remaining electrolytic solution from the periphery of the injection port 7 more reliably when the laser beam is irradiated from the inside to the outside. It is possible to more reliably suppress the occurrence of defects.

  In addition, although electrolyte solution is driven out from the inside by laser beam irradiation from the inside to the outside, the electrolyte solution may remain (for example, return along the heat input portion 8). Therefore, when the electrolyte is sufficiently expelled to the outside of the predetermined region R1, welding is performed on the inner side of the outer edge of the heat input portion 8 (the outer edge of the predetermined region R1), thereby further reducing the occurrence frequency of welding failure. Can do. Further, among the remaining electrolyte, there is an electrolyte that returns to the inside due to a capillary phenomenon when the sealing lid 9 is overlaid on the heat input portion 8 of the lid 3b. Since there is a (wall by each groove 8a) and the electrolyte is absorbed in the circumferential direction, it is difficult to reach the inner depth.

(Second Embodiment)
As shown in FIG. 8, in the present embodiment, the innermost peripheral portion 8d (second portion) located at the innermost periphery among the plurality of adjacent portions 8c of the heat input portion 8 is annular, and more specifically, substantially circular. Is provided. Other portions of the heat input portion 8 other than the innermost peripheral portion 8d are provided in a spiral shape. The other part of the heat input part 8 other than the innermost peripheral part 8 d is an example of a part of the heat input part 8.

  In the present embodiment, the innermost peripheral portion 8d and the alongside portion 8c located adjacent to the innermost peripheral portion 8d on the outer peripheral side of the innermost peripheral portion 8d are formed by continuous irradiation of laser light. And the groove parts 8a which they have are connected. As a modification, the laser beam irradiation is divided between the innermost peripheral portion 8d and the outer peripheral portion 8d on the outer peripheral side of the innermost peripheral portion 8d and adjacent to the innermost peripheral portion 8d. May be. In this case, as shown in FIG. 9, the groove portion 8a of the innermost peripheral portion 8d and the groove portion 8a of the alongside portion 8c located adjacent to the innermost peripheral portion 8d on the outer peripheral side of the innermost peripheral portion 8d are , Discontinuous.

  Here, when the annular innermost peripheral portion 8d is formed, the laser light irradiation along the locus forming the innermost peripheral portion 8d may be performed once or repeatedly (multiple times).

  Also in the present embodiment described above, the electrolytic solution remaining around the liquid injection port 7 can be removed by being evaporated by the heat generated by laser irradiation when the heat input portion 8 is formed.

  According to each embodiment described above, defects caused by the electrolytic solution remaining in the vicinity of the injection port 7 are suppressed to improve the quality of the injection port 7 sealing welding, and the high quality and high quality of the secondary battery 1 are achieved. Reliability can be realized.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  For example, the second portion of the heat input unit 8 may be provided outside the innermost periphery. Moreover, each side part 8c of the heat input part 8 may be formed in an annular shape. Moreover, you may narrow the inner peripheral side of the pitch of the side part 8c of the heat input part 8 compared with the heat input part 8 outer peripheral side.

  DESCRIPTION OF SYMBOLS 1 ... Secondary battery, 2 ... Electrode body, 3 ... Container, 3b ... Cover body, 3c ... Outer surface, 7 ... Liquid injection port, 7a ... Edge, 8 ... Heat input part, 8c ... Along part, 8d ... Innermost circumference Side part, 8f ... outer edge, 9 ... sealing lid, 20 ... laser irradiation apparatus.

Claims (20)

A container having a wall portion provided with an opening and containing an electrode body and an electrolyte;
A heat input portion provided on the wall portion, including a portion provided along an edge of the opening on the outer surface of the wall portion and arranged in a direction away from the opening;
A lid that is fixed to the wall portion in a state of being superimposed on the heat input portion, and that covers the opening;
With
The heat input part has a first part surrounding the opening, and a second part surrounding the opening near the edge than the first part and having a deeper heat input than the first part. Secondary battery.   The secondary battery according to claim 1, wherein the heat input portion is separated from the edge.   The secondary battery according to claim 1, wherein, in the heat input portion, the second portion is positioned closest to the edge.   The secondary battery according to claim 1, wherein the heat input portion is provided in a spiral shape.   The secondary battery according to claim 1, wherein the second portion is provided in a ring shape.   The secondary battery according to claim 5, wherein a part of the heat input portion is provided in a spiral shape. The lid is welded to the wall portion on the opening side of the portion farthest from the opening in the heat input portion,
The secondary according to any one of claims 1 to 6, wherein a depth of heat input from the outer surface to the wall portion in the welding is deeper than a depth of heat input of the second portion from the outer surface. battery.   The distance from the opening-side edge of the heat input portion to the edge of the opening is 0.5 times to 10 times the width along the direction away from the openings of the arranged portions of the heat input portions. The secondary battery according to claim 2, which is a length.   The secondary battery according to claim 1, wherein the heat input portion is provided by irradiating the outer surface with a laser beam. A container having a wall portion provided with an opening and containing an electrode body and an electrolyte;
Including a portion arranged along the edge of the opening on the outer surface of the wall and arranged in a direction away from the opening;
A lid that is fixed to the wall portion in a state of being superimposed on the heat input portion, and that covers the opening;
With
The heat input portion has a first portion surrounding the opening, and a second portion surrounding the opening closer to the edge than the first portion,
The amount of heat input by the laser light per unit area of the outer surface when the second portion is provided is greater than the amount of heat input by the laser light per unit area of the outer surface when the first portion is provided. Many secondary batteries.   The secondary battery according to claim 9 or 10, wherein a scanning speed of the laser light when the second portion is provided is slower than a scanning speed of the laser light when the first portion is provided.   The scanning speed of the laser beam when the first part is provided is in a range of 5 to 20 times the scanning speed of the laser beam when the second part is provided. The secondary battery as described in any one of.   The secondary battery according to claim 9, wherein a scanning speed of the laser beam when the second portion is provided is in a range of 10 mm / s to 500 mm / s.   The laser light irradiation output when the second part is provided in the laser irradiation apparatus that irradiates the laser light is higher than the laser light irradiation output of the laser irradiation apparatus when the first part is provided. The secondary battery according to 10.   The secondary battery according to any one of claims 9 to 14, wherein a laser light irradiation output when the heat input portion is provided in the laser irradiation apparatus that irradiates the laser light is in a range of 300W to 3000W.   The secondary battery according to any one of claims 9 to 15, wherein a wavelength of the laser beam when the heat input portion is provided is in a range of 800 nm to 1300 nm. Direction of moving away from the opening along the edge of the opening on the outer surface of the wall portion by irradiating the outer surface of the wall portion of the container having the wall portion provided with the opening and into which the electrolyte is injected. A step of providing, on the wall, a heat input portion including a portion arranged in
A step of stacking a lid on the heat input portion at a position closing the opening and fixing the lid to the wall portion;
Including
The heat input section includes a first portion that surrounds the opening, and a second portion that surrounds the opening nearer the edge than the first portion and has a deeper heat input than the first portion. ,
A secondary battery in which the amount of heat input by the laser light per unit area of the outer surface when providing the second portion is greater than the amount of heat input by the laser light per unit area of the outer surface when providing the first portion. Manufacturing method.   The method of manufacturing a secondary battery according to claim 17, wherein a scanning speed of the laser light when the second portion is provided is slower than a scanning speed of the laser light when the first portion is provided.   The scanning speed of the laser beam when the first portion is provided is in the range of 5 to 20 times the scanning speed of the laser beam when the second portion is provided. The manufacturing method of the secondary battery as described in any one of.   The laser light irradiation output when the second part is provided in the laser irradiation apparatus that irradiates the laser light is higher than the laser light irradiation output of the laser irradiation apparatus when the first part is provided. The manufacturing method of the secondary battery as described.

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