electrochemical cell

Abstract

To obtain sure sealability.SOLUTION: An electrochemical cell 1 includes an exterior body 2 having a first container 20 having a first joint wall 12, and a second container 20 that has a second joint wall 21 welded and joined to the first joint wall and forms a storage space 4 between the first container and the second container, an electrode body 30 that has a positive electrode and a negative electrode and is stored in a storage space, and a current collecting plate 61 which is welded to the first container through an insulating resin material 60 and is at least partially exposed to the outside, wherein a welding mark is formed in the second joint wall.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention provides electrochemical cell Regarding. [Background technology]

[0002] Electrochemical cells such as lithium-ion secondary batteries and electrochemical capacitors have been widely used as power sources for small electronic devices and wearable devices, including wristwatches, smartwatches, smartphones, headsets, and hearing aids. In recent years, there has been an increasing demand for smaller and thinner electrochemical cells of this type. One reason for this is that, as the performance of various electronic devices incorporating electrochemical cells improves due to the miniaturization and reduced power consumption of integrated circuits (ICs), electronic devices equipped with unprecedented high-spec functions are beginning to be proposed.

[0003] Known electrochemical cells of this type use, for example, a metal case as an exterior housing for housing the electrode assembly inside. The metal case includes, for example, a cylindrical case body with a bottom and a sealing plate that seals the opening of the case body by crimping or the like with a resin gasket interposed therebetween, and is often configured as a coin, button, cylindrical, or other shape as a whole.

[0004] However, when the case body and the sealing plate are sealed by crimping or the like, sufficient sealing may not be achieved and the volumetric efficiency tends to be poor. Note that volumetric efficiency refers to the ratio of the volume occupied by the electrodes to the total volume of the battery, i.e., "electrode volume / total battery volume." Therefore, instead of fixing the case body and the sealing plate by crimping or the like, it is conceivable to improve sealing performance by welding the case body and the sealing plate together by laser welding (see, for example, Patent Document 1) or resistance welding (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 63-239764 [Patent Document 2] Japanese Patent Application Publication No. 11-260326 Summary of the Invention [Problem to be solved by the invention]

[0006] When the exterior body is constructed by welding the case body and the sealing plate, a metal current collector plate that functions as an external connection terminal for the positive electrode or the negative electrode is often attached to the case body or the sealing plate via an insulating resin material such as a resin seal. This makes it possible, for example, to electrically connect one of the positive electrode and the negative electrode that constitute the electrode assembly housed inside the exterior body to the case body and electrically connect the other electrode to the current collector. Therefore, the case body and the current collector plate can function as external connection terminals for the positive electrode and the negative electrode, respectively.

[0007] However, in this case, the heat (welding heat) applied when welding the case body and the sealing plate together may plasticize the resin material, causing it to peel off. In this case, the sealing performance may be easily reduced, and leakage may occur due to evaporation of the electrolyte, etc. In particular, in the case of the small electrochemical cells mentioned above, the resin material is prone to plasticization due to the influence of welding heat not only at the weld where the molten pool solidifies during welding and in the heat-affected zone (HAZ) around the weld, but also in the vicinity of the heat-affected zone.

[0008] The present invention has been made in consideration of such circumstances, and its object is to provide a seal that can provide reliable sealing. electrochemical cell The purpose is to provide [Means for solving the problem]

[0009] (1) The electrochemical cell according to the present invention includes an exterior body including a first container having a first joint wall and a second container having a second joint wall welded to the first joint wall and forming a storage space between the first container and the second container; an electrode assembly having a positive electrode and a negative electrode and housed in the storage space; and a current collector plate welded to the first container via an insulating resin material and at least a portion of which is exposed to the outside, and the second joint wall has weld marks formed thereon. The first joint wall and the second joint wall are welded together via a weld metal layer formed between the first joint wall and the second joint wall, the first container is formed in a bottomed tubular shape having a bottom wall to which the current collecting plate is welded via the resin material and a peripheral wall, the second container has a flange portion overlapping an upper opening edge of the peripheral wall portion from above, and the opening of the first container is closed by welding the flange portion to the peripheral wall portion, the peripheral wall portion being the first joint wall, and the flange portion being the second joint wall, and the weld metal layer being formed between the upper opening edge of the peripheral wall portion and the flange portion. It is characterized by:

[0010] In the electrochemical cell according to the present invention, the first and second containers are integrally combined by welding the first and second container walls together, thereby appropriately sealing the storage space in which the electrode assembly is housed. In particular, as is clear from the weld marks formed on the second container wall, the first and second containers are welded together by heating from the second container wall side, rather than from the first container wall side to which the current collector plate is welded via the resin material. This prevents heat applied during welding (welding heat) from being transferred to the resin material. Therefore, the resin material can be made less susceptible to the effects of welding heat and can be prevented from melting or plasticizing due to an unintended temperature rise. This prevents problems such as peeling of the resin material and ensures reliable sealing of the storage space. This allows, for example, the current collector plate to function as an external connection terminal, and results in a high-quality electrochemical cell with high operational reliability. Furthermore, since the first and second joining walls are welded together via a weld metal layer formed, for example, by melting and solidifying a metal plating film, the first and second containers can be joined together even more firmly, thereby improving the sealing performance within the storage space. Furthermore, during welding, a weld metal layer can be formed between the peripheral wall and the flange by applying heat, for example, a laser beam, from above the flange that overlaps the upper opening edge of the peripheral wall. This allows the first container and the second container to be firmly welded together via the weld metal layer. In particular, when forming the weld metal layer by heating from the flange side, it is easy to form a deep molten pool in which the metal plating film or the like is melted using the peripheral wall, thereby increasing the strength of the weld joint.

[0011] (2) The weld marks may be formed on an opposing surface of the second joint wall that is located on the opposite side to the joint surface welded to the first joint wall.

[0012] In this case, welding marks (e.g., laser welding marks caused by irradiating a laser beam, welding marks caused by applying pressure and current to a roller electrode, etc.) are formed on the opposing surfaces of the second joining wall, so that by heating from the second joining wall side, the first container and the second container can be securely welded together to form an outer casing.

[0015] ( 3 The weld metal layer may have a melting point lower than that of the base metal constituting the first container and that of the base metal constituting the second container.

[0016] In this case, the melting point of the weld metal layer is lower than that of the base metals of the first and second containers, so the amount of heat generated during welding can be reduced, making it difficult for the resin material to be heated, effectively preventing problems such as peeling of the resin material.

[0019] ( 4 The weld metal layer may be formed so as to wrap around the outer circumferential surface of the flange portion and cover the outer circumferential surface of the flange portion.

[0020] In this case, the weld metal layer is formed not only between the peripheral wall portion and the flange portion but also so as to cover the outer peripheral surface of the flange portion, thereby further increasing the weld joint strength between the first container and the second container.

[0021] ( 5 ) The electrochemical cell according to the present invention comprises an exterior body including a first container having a first joint wall and a second container having a second joint wall welded to the first joint wall and forming a storage space between the first container and the second container; an electrode assembly having a positive electrode and a negative electrode and housed in the storage space; and a current collector plate welded to the first container via an insulating resin material and at least a portion of which is exposed to the outside, wherein weld marks are formed on the second joint wall, The first container is formed in a topped cylindrical shape having a top wall portion to which the current collecting plate is welded via the resin material and a first peripheral wall portion, and the second container is formed in a bottomed cylindrical shape having a bottom wall portion and a second peripheral wall portion welded to the outside of the first peripheral wall portion around the entire circumference, the first peripheral wall portion being the first joint wall, the second peripheral wall portion being the second joint wall, and the weld marks being formed on the outer peripheral surface of the second peripheral wall portion. It is characterized by the presence of

[0022] In this case, the first peripheral wall portion of the first container and the second peripheral wall portion of the second container are combined into a double cylindrical shape, and then heating is performed from the outside of the second peripheral wall portion, thereby welding the first peripheral wall portion and the second peripheral wall portion together around the entire circumference while forming weld marks on the outer circumferential surface of the second peripheral wall portion. In particular, because the first peripheral wall portion and the second peripheral wall portion are welded together while combined into a double cylindrical shape, the airtightness within the storage space can be further improved, and the sealing performance can be enhanced. Furthermore, since welding can be performed at a position away from the top wall portion where the resin material is welded, the heat transfer distance to the resin material can be increased, making it difficult for welding heat to be transferred to the resin material. In addition, since the first peripheral wall portion and the second peripheral wall portion are in surface contact, the welding heat can be easily dispersed, making it difficult for welding heat to be transferred to the resin material. Therefore, problems such as peeling of the resin material can be effectively prevented.

[0023] ( 6 ) The weld mark may be formed on an opposing surface of the second joint wall that is located on the opposite side to a joint surface that is welded to the first joint wall.

[0024] (7) The first joint wall and the second joint wall may be welded together via a weld metal layer formed between the first joint wall and the second joint wall.

[0025] ( 8 ) The weld metal layer may have a melting point lower than that of the base metal constituting the first container and that of the base metal constituting the second container. [Effects of the Invention]

[0033] According to the present invention, an electrochemical cell that can obtain reliable sealing can be obtained. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a perspective view showing a first embodiment of a secondary battery (electrochemical cell) according to the present invention. [Figure 2] 2 is a longitudinal cross-sectional view of the secondary battery taken along line AA shown in FIG. [Figure 3] FIG. 3 is an enlarged cross-sectional view of the periphery of the weld metal layer shown in FIG. 2. [Figure 4] FIG. 3 is a perspective view of the electrode body shown in FIG. [Figure 5]5 is a longitudinal cross-sectional view of the electrode body taken along line BB shown in FIG. 4. [Figure 6] FIG. 10 is a cross-sectional view showing a modified example of the weld metal layer. [Figure 7] FIG. 2 is a perspective view of a secondary battery showing a modified example of the first embodiment. [Figure 8] FIG. 2 is a longitudinal sectional view showing a second embodiment of a secondary battery (electrochemical cell) according to the present invention. [Figure 9] FIG. 10 is a perspective view showing a third embodiment of a secondary battery (electrochemical cell) according to the present invention. [Figure 10] 10 is a longitudinal cross-sectional view of the secondary battery taken along line CC shown in FIG. 9. [Figure 11] FIG. 11 is a longitudinal sectional view of a secondary battery showing a modified example of the third embodiment. [Figure 12] FIG. 12 is a partially enlarged cross-sectional view of the container body shown in FIG. [Figure 13] FIG. 10 is a longitudinal sectional view showing a fourth embodiment of a secondary battery (electrochemical cell) according to the present invention. [Figure 14] FIG. 10 is a vertical cross-sectional view showing a fifth embodiment of a secondary battery (electrochemical cell) according to the present invention. [Figure 15] FIG. 15 is a perspective view of the secondary battery shown in FIG. 14, in which laser welding marks are formed all around the upper end side of the peripheral wall portion. [Figure 16] FIG. 15 is a perspective view of the secondary battery shown in FIG. 14, in which laser welding marks are formed all around the center of the peripheral wall portion. [Figure 17] 15 is a perspective view of the secondary battery shown in FIG. 14, in which laser welding marks are formed all around the upper and lower end sides of the peripheral wall portion. FIG. [Figure 18] 15 is a vertical cross-sectional view showing a modified example of the secondary battery shown in FIG. [Figure 19] FIG. 10 is a longitudinal sectional view showing a sixth embodiment of a secondary battery (electrochemical cell) according to the present invention. [Figure 20] FIG. 20 is a diagram showing one process of winding the electrode body shown in FIG. 19 around a support rod, showing a state in which a separator has been fixed to the outer peripheral surface of the support rod. [Figure 21] 21 is a diagram showing a state in which the support column is rotated from the state shown in FIG. 20 and the separator is wound around the support column first. FIG. [Figure 22] FIG. 10 is a perspective view showing a modified example of the electrode body according to the present invention. [Figure 23] FIG. 23 is a perspective view of the combined state of a pair of positive and negative electrodes shown in FIG. 22, with the negative electrode facing upward. [Figure 24] FIG. 24 is an exploded view for explaining the combined state of a pair of positive and negative electrodes shown in FIG. 23. [Figure 25] FIG. 10 is a perspective view showing a modified example of the electrode body according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0035] (First embodiment) Hereinafter, an embodiment of an electrochemical cell according to the present invention will be described with reference to the drawings. In this embodiment, a lithium ion secondary battery (hereinafter simply referred to as a secondary battery), which is a type of non-aqueous electrolyte secondary battery, will be described as an example of the electrochemical cell.

[0036] As shown in Figures 1 and 2, the secondary battery 1 of this embodiment is a so-called button (coin) type battery, and includes a metal exterior body 2 and a power generating element 3 housed inside the exterior body 2.

[0037] The outer casing 2 comprises a metal container body (first container according to the present invention) 10 formed in a cylindrical shape with a bottom, and a metal lid member (second container according to the present invention) 20 welded to the container body 10 so as to close the opening of the container body 10, forming a storage space between the container body 10 and the lid member. The power generating element 3 includes an electrode body 30 having a positive electrode 40 and a negative electrode 50, and contains an electrolyte (electrolyte solution) not shown, and is housed in a housing space 4 formed inside the outer casing 2.

[0038] In this embodiment, the axis that passes through the center of the exterior body 2 and extends in the vertical direction is referred to as the battery axis O. In addition, in a plan view seen from the direction of the battery axis O, the direction that intersects with the battery axis O is referred to as the radial direction, and the direction that goes around the battery axis O is referred to as the circumferential direction. Furthermore, the direction from the bottom wall 11 of the container body 10 toward the lid member 20 along the battery axis O is referred to as the upward direction, and the opposite direction is referred to as the downward direction.

[0039] (exterior body) The exterior body 2 will now be described in detail. The container body 10 is formed in a cylindrical shape with a bottom, and includes a bottom wall portion 11 formed in a circular shape when viewed from above, and a peripheral wall portion 12 that is connected around the entire outer peripheral edge of the bottom wall portion 11 and extends upward from the bottom wall portion 11. However, the shape of the container body 10 is not limited to a cylindrical shape with a bottom, and may be formed so that the outer shape is, for example, elliptical, rectangular, or polygonal in plan view.

[0040] A through-hole 13 that passes through the bottom wall 11 in the vertical direction is formed in the center of the bottom wall 11 and is coaxial with the battery axis O. The shape of the through-hole 13 is not particularly limited, but is formed, for example, in a circular shape when viewed from above.

[0041] The container body 10 configured as described above is made of metal and functions as an external connection terminal for a positive electrode or an external connection terminal for a negative electrode that is electrically connected to the electrode body 30. The thickness of the container body 10 is, for example, about 0.01 mm to 0.30 mm, making it a thin-walled metal container. However, in each drawing, the thickness of the container body 10 is exaggerated for ease of illustration.

[0042] The specific metal material of the container body 10 varies depending on whether the container body 10 is to function as an external connection terminal for a positive electrode or an external connection terminal for a negative electrode, but may be, for example, aluminum, aluminum alloy, copper, copper alloy, stainless steel, or a clad material (highly functional metal material) formed by pressure-bonding the same or different metals together, but is not limited to these. Examples of stainless steel include ferritic stainless steels such as SUS430 and SUS444, and austenitic-ferritic duplex stainless steels such as SUS329J4L.

[0043] Furthermore, for example, when the secondary battery 1 of this embodiment is used in a watch, it is preferable that the metallic material of the container body 10 is non-magnetic in addition to being corrosion-resistant. Specific examples include aluminum, aluminum alloys, copper, and copper alloys as described above, as well as stainless steels such as various austenitic stainless steels such as SUS201, SUS202, SUS303, SUS304, SUS305, SUS316, SUS317, SUS321, and SUS347.

[0044] Examples of clad materials include a three-layer clad material of Cu (inner layer) / Fe (middle layer) / Ni (outer layer), a three-layer clad material of Ni (inner layer) / Fe (middle layer) / Ni (outer layer), a three-layer clad material of Al (inner layer) / SUS (middle layer) / Ni (outer layer), etc. However, the clad material is not limited to three layers, and may be formed by pressure bonding other metals together in multiple layers.

[0045] When Cu is used as the clad material, the thermal conductivity can be increased, and therefore the heat dissipation during welding can be improved. Therefore, using Cu as the inner layer of the clad material is preferable because it can protect the electrode body 30.

[0046] Furthermore, it is preferable to form a metal plating film by plating either the inner surface or the outer surface of the clad material, or both the inner surface and the outer surface. Forming a metal plating film on the inner surface of the container body 10 can provide chemical stability and improve resistance to electrolytes, etc. Furthermore, forming a metal plating film on the outer surface of the container body 10 can provide functions such as rust prevention and reduce electrical resistance, thereby improving electrical connectivity with external terminals.

[0047] Specific examples of the metal plating film include Ni plating film and Ni alloy plating film, and it is particularly preferable to use an alloy plating film of a eutectic metal material. When an alloy plating film of a eutectic metal material is used, the melting point can be lowered when resistance welding is performed, and the welding temperature can be lowered. Other suitable materials include an Au-Ni alloy plating film, an Ni-P alloy plating film, and an Ni-B alloy plating film.

[0048] 1 and 2, the lid member 20 is formed in the shape of a flat plate facing the bottom wall 11 of the container body 10 in the direction of the battery axis O with the electrode body 30 sandwiched therebetween, and is welded and joined to the upper opening end of the peripheral wall 12 of the container body 10 in a state where it overlaps from above around the entire periphery. Therefore, the outer peripheral edge of the lid member 20 functions as a flange portion 21 that overlaps from above with the upper opening end of the peripheral wall 12.

[0049] The shape of the lid member 20 only needs to correspond to the shape of the container body 10, and may be formed so that the outer shape is, for example, elliptical, rectangular, or polygonal in plan view. The thickness of the lid member 20 is thin, for example, about 0.01 mm to 0.30 mm, similar to the container body 10. However, in FIG. 2, the thickness of the lid member 20 is exaggerated for ease of illustration. This also applies to the other drawings.

[0050] The lid member 20 configured as above is made of metal. As a specific metal material for the lid member 20, for example, the same type of metal as that of the container body 10 or a different type of metal material can be used. When a different type of metal material from that of the container body 10 is used as the metal material for the lid member 20, it is preferable to use a material with a thermal expansion coefficient similar to that of the container body 10. Furthermore, it is preferable to form a metal plating film on either the inner surface or the outer surface, or both the inner surface and the outer surface, of the lid member 20, similarly to the container body 10. As the metal plating film, the metal plating film described above can be used.

[0051] During assembly, the lid member 20 configured as described above is placed on the upper opening edge of the peripheral wall portion 12 of the container body 10 from above, and then welded while applying pressure from above, for example. As a result, as described above, the peripheral wall portion 12 and the flange portion 21 are firmly joined by welding around the entire periphery. This allows the lid member 20 to close the opening of the container body 10, and forms an accommodation space 4 (sealed space) between the lid member 20 and the container body 10 to accommodate the power generating element 3. Therefore, the flange portion 21 of the lid member 20 functions as a joining wall (second joining wall according to the present invention) that is welded to the peripheral wall portion 12 of the container body 10 (first joining wall according to the present invention).

[0052] The method for welding the container body 10 and the lid member 20 is not particularly limited, but examples that can be used include resistance welding such as laser welding, ultrasonic welding, and seam welding, as well as friction stir welding (FSW). During these welding operations, the welding may be performed by a so-called workpiece movement method, in which the welding tool (not shown) is fixed and the exterior body 2, which is the work to be welded, is moved, or the welding may be performed by a so-called head movement method, in which the exterior body 2, which is the work to be welded, is fixed and the welding tool is moved.When laser welding is performed, a galvano scanning laser welder or the like can also be used.

[0053] In this embodiment, the lid member 20 is welded onto the upper opening edge of the peripheral wall portion 12 of the container body 10 from above, so it is preferable to use the galvano scanning method and laser welding in combination with the head movement method.

[0054] Specifically, as shown in Figure 3, the outer casing 2 of this embodiment is welded together the peripheral wall portion 12 of the container body 10 and the flange portion 21 of the lid member 20 via a weld metal layer (so-called boundary layer) 5 formed between the upper opening edge of the peripheral wall portion 12 and the flange portion 21. Therefore, in the container body 10 of this embodiment, the first metal film 6 is formed at least on the upper opening edge of the peripheral wall portion 12, and the second metal film 7 is formed at least on the lower surface 21a of the flange portion 21 in the lid member 20. Then, the first metal film 6 and the second metal film 7 are melted together by the heat (welding heat) applied during welding and then solidified, thereby forming the weld metal layer 5.

[0055] 3 illustrates a state in which the first metal film 6 is formed only on the upper opening edge of the peripheral wall portion 12, but the first metal film 6 may be formed over the inner surface of the container body 10 or over the entire surface of the container body 10. Similarly, while FIG. 3 illustrates a state in which the second metal film 7 is formed only on the lower surface 21a of the flange portion 21, the second metal film 7 may be formed over the entire lower surface of the lid member 20 (including the lower surface 21a of the flange portion 21) or over the entire surface of the lid member 20. The first metal film 6 and the second metal film 7 may be made of any of the various metal plating films described above.

[0056] In particular, in this embodiment, when welding the peripheral wall 12 of the container body 10 and the flange 21 of the lid member 20 together, a laser beam is irradiated from above the flange 21 to heat the interface between the peripheral wall 12 and the flange 21, thereby performing welding. This point will be described later. 1, laser welding marks (welding marks according to the present invention) 9 are formed on an upper surface (opposing surface according to the present invention) 21b of flange portion 21, which is located opposite to a lower surface (joining surface according to the present invention) 21a that is welded to peripheral wall portion 12. Laser welding marks 9 are formed continuously, for example, around the entire circumference of flange portion 21.

[0057] Here, the laser welding mark 9 includes a weld formed by solidifying a molten pool that is generated when metal melts during welding, and a heat-affected zone (HAZ) formed around the weld. The heat-affected zone is a part (area) that does not melt during welding but has a structure (composition) different from the original structure due to the influence of welding heat, oxidation, etc. In this embodiment, as described above, the container body 10 and the lid member 20 are welded together by melting the first metal film 6 formed on the container body 10 and the second metal film 7 formed on the lid member 20, as described with reference to FIG. 3 . However, even if the first metal film 6 and the second metal film 7 are not used, it is possible to locally heat and melt the upper opening edge of the peripheral wall portion 12 of the container body 10 and the lower surface 21 a of the flange portion 21 of the lid member 20 by irradiating them with a laser beam from above the flange portion 21. Then, by solidifying the molten pool formed by the fusion of the upper opening edge of the peripheral wall portion 12 and the lower surface 21 a of the flange portion 21, a molten metal portion (not shown) can be formed, thereby welding the container body 10 and the lid member 20 together. Even in this case, the laser weld marks 9 are continuously formed around the entire periphery, for example, on the upper surface 21 b of the flange portion 21.

[0058] (current collector plate) As shown in FIG. 2, the bottom wall 11 of the container body 10 configured as described above is provided with a current collector plate 61 that is heat-welded (sealed) via a sealant film (insulating resin material according to the present invention) 60, and at least a portion of which is exposed to the outside (downward). Specifically, the sealant film 60 and the current collecting plate 61 are disposed on the lower surface of the bottom wall 11, facing away from the accommodation space 4 in the direction of the battery axis O. The current collecting plate 61 is heat-welded to the lower surface of the bottom wall 11 via the sealant film 60, and is exposed downward over its entire surface.

[0059] The sealant film 60 is formed in a ring shape surrounding the through-hole 13 formed in the bottom wall portion 11, and is arranged so as to overlap the lower surface of the bottom wall portion 11 while being coaxial with the battery axis O. In the illustrated example, the sealant film 60 is formed with an inner diameter smaller than the diameter of the through-hole 13. However, this is not limited to this, and the inner diameter of the sealant film 60 may be formed to be equal to or larger than the diameter of the through-hole 13.

[0060] Furthermore, the sealant film 60 is formed so as to be folded upward from the inner peripheral edge portion, and is provided with a protective portion 60a that covers the entire inner peripheral surface of the through-hole 13 of the bottom wall portion 11 from the inside in the radial direction. This is preferable because it can prevent unintended electrical connection (short circuit) from the inside of the through-hole 13 to the container body 10.

[0061] The sealant film 60 is made of, for example, a thermoplastic resin such as polyolefin, or an engineering plastic such as polyphenylene sulfide (PPS). Examples of polyolefin include polyethylene, polypropylene, and polybutene. Furthermore, a copolymer or blend polymer of each of the above-mentioned polyolefins, or a composite such as polypropylene reinforced with nonwoven fabric may also be used as the sealant film 60. Furthermore, a plurality of sealant films 60 with different dimensions, shapes, or thicknesses may be stacked and used.

[0062] Furthermore, it is preferable to use a fluorine-based resin for the sealant film 60. Specific examples of the fluorine-based resin include FEP (perfluoroethylene propene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer resin), ETFE (ethylene tetrafluoroethylene copolymer, tetrafluoroethylene-ethylene copolymer resin), and PFA (perfluoroalkoxyalkane, tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin).

[0063] Generally, fluororesin has a high melting point and therefore has high heat resistance. Therefore, when a fluororesin sealant film 60 is used, the influence of welding heat on the sealant film 60 can be more effectively suppressed during welding (heat sealing) of the container body (first container) 10 and the lid member (second container) 20. Furthermore, fluororesin is a resin that has high chemical resistance and high density, so even when the sealant film 60 is made of fluororesin, it can still provide sufficient sealing properties as a sealant film 60. Furthermore, fluororesin has the property of having a small coefficient of linear expansion, so when the sealant film 60 is made of fluororesin, it is less likely to expand thermally when the container body (first container) 10 and the lid member (second container) 20 are welded together, and in this respect, it also has excellent sealing properties.

[0064] In the case of a fluorine-based resin sealant film 60, the melting point tends to be preferably within a temperature range of, for example, 260°C to 270°C in terms of processability during fusion. In terms of deterioration characteristics during storage, the lower the water absorption rate, the more preferable. Furthermore, in terms of resistance to temperature changes, the lower the linear expansion coefficient, the more preferable. Therefore, when using a fluorine-based resin sealant film 60, it is advisable to appropriately select a specific material (FEP, ETFE, PFA) in consideration of the melting point, water absorption rate, linear expansion coefficient, and other physical properties.

[0065] The current collecting plate 61 is a metal plate that functions as an external connection terminal for a positive electrode or an external connection terminal for a negative electrode that is electrically connected to the electrode body 30. In the illustrated example, the current collecting plate 61 is formed in a circular shape in a plan view with a diameter smaller than the outer diameter of the sealant film 60, and is arranged coaxially with the battery axis O so as to overlap the lower surface of the sealant film 60. In this way, the current collecting plate 61 blocks the through-hole 13 from below.

[0066] The material of the current collector plate 61 is not particularly limited, but nickel, for example, can be suitably used. Furthermore, a metal film made of a highly conductive material such as gold or nickel, or an alloy film containing these metals, may be formed on the surface of the current collector plate 61 that can be connected to the outside.

[0067] The above-mentioned sealant film 60 is heat-welded to the lower surface of the bottom wall portion 11 and the upper surface of the current collector plate 61. Specifically, the sealant film 60 is formed by heat-welding together a first sealant made of synthetic resin that is integrally combined with the upper surface of the current collector plate 61 by heat welding, and a second sealant made of synthetic resin that is integrally combined with the lower surface of the bottom wall portion 11 by heat welding. As a result, the current collector plate 61 is heat-welded to the lower surface of the bottom wall portion 11 via the sealant film 60, and the through-hole 13 is airtightly sealed from below while maintaining insulation between the current collector plate 61 and the container body 10.

[0068] The present invention is not limited to the use of the first and second sealing materials described above, and the sealant film 60 may be directly heat-sealed to the bottom wall portion 11 and the current collector plate 61, for example. In particular, when the current collecting plate 61 is heat-welded to the bottom wall portion 11 using a fluorine-based resin sealant film 60, fluorine-based resins tend not to absorb electromagnetic waves well, so it is preferable to inductively heat the current collecting plate 61 side rather than directly heating the sealant film 60 side (dielectric heating). In this case, in order to avoid localized discharge and reflection of electrons, it is preferable to increase the surface roughness of the current collecting plate 61 rather than making it smooth. In this case, it is acceptable to increase the surface roughness of at least the portion of the surface of the current collecting plate 61 where the sealant film 60 is heat-welded, but it is preferable to increase the surface roughness of the entire current collecting plate 61. Furthermore, as a method for avoiding localized discharge and reflection of electrons, as mentioned above, it is preferable to form the current collector plate 61 into a shape with a smooth surface and no edges, and in addition to increasing the surface roughness as described above, the following method is also effective. That is, it is also effective to remove the corners of the current collector plate 61 by C-chamfering using press working or forging, or by filleting.

[0069] The sealant film 60 insulates the current collector 61 from the container 10. Therefore, the secondary battery 1 of this embodiment can be electrically connected to either the positive or negative terminal of an electronic device by bringing the current collector 61 and the container 10 into contact with a pressure terminal, a holder, or the like of the electronic device (not shown). Alternatively, a metal terminal may be further welded to at least one of the current collector 61 and the container 10, and then electrically connected to an electronic device by soldering, welding, or the like. For example, in a structure in which the current collector 61 and the container 10 are arranged at the outermost positions in the vertical direction, such as the secondary battery 1 shown in FIGS. 1 and 2, flat (linear in cross section) terminals (not shown) can be welded to the current collector 61 and the container 10 by laser welding or the like. This makes it possible to suppress an increase in the thickness of the battery in the vertical direction, even when the terminals are welded. Note that such terminals can be made of stainless steel, such as SUS304.

[0070] (power generation element) The power generating element 3 shown in FIG. 2 includes an electrode assembly 30 and an electrolyte solution (not shown), and is housed in a sealed state in a housing space 4 inside the exterior body 2. The electrolyte may be, for example, a liquid in which a supporting salt is dissolved in an aprotic, non-aqueous solvent. The supporting salt may be, for example, lithium fluorophosphate (LiPF6). The solvent may be, for example, ethylene carbonate (EC) and a low-boiling-point solvent.

[0071] However, the power generating element 3 may employ an electrode assembly 30 that uses an electrolyte such as a solid electrolyte, a polymer electrolyte, or a gel electrolyte instead of an electrolytic solution. Examples of polymer electrolytes include polyethylene oxide (PEO), polypropylene oxide (PPO), blend polymers containing these, polyacrylic acid ester, polymethacrylic acid ester, polysiloxane, and polyphosphazene. Alternatively, a gel electrolyte containing poly(vinylidene fluoride-co-hexafluoropropylene, PVdF-HFP) may be used as the electrolytic solution.

[0072] (electrode body) 4 and 5, the electrode assembly 30 is a so-called laminated electrode in which positive electrodes 40 and negative electrodes 50 are alternately laminated in the direction of the battery axis O with separators (not shown) sandwiched between them, for example, by flatly winding them. Note that the illustration of the electrode assembly 30 is simplified in FIG. 2. The electrode body 30 is formed so that its outer shape is circular in plan view, but the outer shape of the electrode body 30 is not limited to this case and may be other shapes such as an ellipse, an oval shape, or a diamond shape, and may be changed as appropriate.

[0073] In this embodiment, the positive electrode 40 and the negative electrode 50 are alternately stacked by being wound with a separator sandwiched therebetween. However, this is not limited to this, and for example, the positive electrode 40 and the negative electrode 50 may be alternately stacked by being folded in a zigzag shape from directions that intersect with each other. Furthermore, a so-called pellet-type electrode body having the positive electrode 40 and the negative electrode 50 on both sides of the separator may also be used.

[0074] The structure of the electrode body 30 will now be briefly described. The positive electrode 40 includes a positive electrode current collector (positive electrode current collector foil) 41 formed in a strip shape in the unfolded state before being wound, and a positive electrode active material layer (not shown) formed on both sides of the positive electrode current collector 41.

[0075] The positive electrode current collector 41 is formed in the form of a thin sheet (metal foil) made of a metal material such as aluminum, aluminum alloy, or stainless steel, and includes a plurality of positive electrode bodies 42 and a plurality of positive electrode connection pieces 43. The thickness of the positive electrode current collector 41 is, for example, about several μm to 10 and several μm. In addition to metal foil, the positive electrode current collector 41 may be made of, for example, etched foil, embossed foil (textured), punched metal (through-hole processed), expanded metal, sintered metal, or metal foam. The positive electrode bodies 42 are formed, for example, in a disk shape and are arranged at intervals so as to be aligned in a row in the unfolded state before winding. The positive electrode connection pieces 43 are arranged between adjacent positive electrode bodies 42 in the unfolded state before winding, and connect the adjacent positive electrode bodies 42 to each other. Of the multiple positive electrode bodies 42, a positive electrode terminal tab 44 is formed on the positive electrode body 42 that is arranged on the outermost periphery in the wound state.

[0076] The positive electrode active material layer is formed on both surfaces of the positive electrode current collector 41 excluding the positive electrode terminal tab 44. As a material for forming the positive electrode active material layer, a positive electrode slurry can be prepared by mixing a positive electrode active material with a conductive additive (e.g., carbon black, graphite, etc.), a binder (e.g., polyvinylidene fluoride, etc.), and a solvent (e.g., any solvent such as N-methylpyrrolidone). Note that a coating liquid containing the constituent materials for forming the positive electrode active material layer can be referred to as a "positive electrode slurry." The positive electrode active material layer can be formed by applying this positive electrode slurry to the positive electrode current collector 41 and drying it. Examples of the positive electrode active material include composite oxides containing lithium and transition metals, such as nickel-manganese-cobalt lithium oxide (NMC), nickel-cobalt lithium aluminum oxide (NCA), lithium titanate (LTO), and lithium manganese oxide (LMO).

[0077] The negative electrode 50 includes a negative electrode current collector (negative electrode current collector foil) 51 formed in a strip shape in the unfolded state before being wound, and a negative electrode active material layer (not shown) formed on both sides of the negative electrode current collector 51.

[0078] The negative electrode current collector 51 is formed in the form of a thin sheet (metal foil) made of a metal material such as copper, copper alloy, nickel, or stainless steel, and includes a plurality of negative electrode bodies 52 and a plurality of negative electrode connection pieces 53. The thickness of the negative electrode current collector 51 is, for example, about several μm to 10 and several μm. In addition to metal foil, the negative electrode current collector 51 may be made of, for example, etched foil, embossed foil (textured), punched metal (through-hole processed), expanded metal, sintered metal, or metal foam. The negative electrode bodies 52 are formed, for example, in a disk shape, similar to the positive electrode bodies 42, and are arranged at intervals in the unfolded state before winding. The negative electrode connecting pieces 53 are arranged between adjacent negative electrode bodies 52 in the unfolded state before winding, and connect the adjacent negative electrode bodies 52 to each other. Of the multiple negative electrode bodies 52, a negative electrode terminal tab 54 is formed on the negative electrode body 52 that is arranged on the outermost periphery in the wound state.

[0079] The negative electrode 50 has an outer shape similar to that of the positive electrode 40 described above. However, the outer size of the positive electrode 40 is formed to be slightly smaller (slightly smaller) than that of the negative electrode 50. Specifically, the outer diameter of the positive electrode 40 is preferably equal to or greater than the thickness of the positive electrode 40 and smaller than that of the negative electrode 50. For example, the outer size of the positive electrode 40 is preferably smaller than that of the negative electrode 50 by 20 μm or more, and more preferably by 50 μm or more.

[0080] The negative electrode active material layer is formed on both surfaces of the negative electrode current collector 51, excluding the negative electrode terminal tab 54. The negative electrode active material layer can be formed by mixing a negative electrode active material with a conductive additive (e.g., carbon black, graphite, etc.), a binder (e.g., a dispersion of styrene-butadiene rubber (SBR)), a thickener (e.g., cellulose nanofiber (CNF), carboxymethyl cellulose (CMC), etc.), and a solvent (e.g., any solvent such as pure water) to form a negative electrode slurry. A coating liquid containing the constituent materials for forming the negative electrode active material layer can be referred to as a "negative electrode slurry." The negative electrode active material layer can be formed by applying the negative electrode slurry to the negative electrode current collector 51 and drying it. Examples of the negative electrode active material include silicon, silicon oxide, graphite, hard carbon, lithium titanate (LTO), LiAl, and the like, either singly or in mixture.

[0081] The positive electrode 40 and negative electrode 50 configured as described above are wound with the separator sandwiched therebetween, and are stacked alternately. Then, in the electrode assembly 30 obtained by winding, as shown in Figures 4 and 5, the positive electrode main body 42 on which the positive electrode terminal tab 44 is formed is located at the bottom, and the negative electrode main body 52 on which the negative electrode terminal tab 54 is formed is located at the top. Therefore, the electrode assembly 30 is housed in the exterior body 2 in a state where the positive electrode terminal tab 44 faces downward and the negative electrode terminal tab 54 faces upward.

[0082] The separator is formed of, for example, a microporous film made of a resin such as polyolefin, a nonwoven fabric made of glass or resin, a laminate of fibers such as cellulose fibers, etc., and is capable of passing lithium ions through ion permeable pores (not shown). Further, as the separator, for example, a porous body capable of retaining an electrolyte solution in the pores, a resin layer having lithium ion conductivity, etc. can be used.

[0083] Furthermore, in the electrode body 30, one of the positive electrode 40 and the negative electrode 50 is electrically connected to the current collector plate 61, and the other electrode is electrically connected to the lid member 20 (or the container body 10). Note that examples of the electrical connection include contact via a carbon-based material, welding of metals to each other, or contact of metals to each other.

[0084] In this embodiment, the negative electrode 50 is electrically connected to the lid member 20, and the positive electrode 40 is electrically connected to the current collector 61. This allows the current collector 61 to function as an external connection terminal for the positive electrode, and the lid member 20 to function as an external connection terminal for the negative electrode. However, this is not limited to this case, and the negative electrode 50 may be electrically connected to the current collector 61, so that the current collector 61 functions as an external connection terminal for the negative electrode, and the positive electrode 40 may be electrically connected to the lid member 20, so that the lid member 20 functions as an external connection terminal for the positive electrode.

[0085] When electrically connecting the negative electrode 50 to the lid member 20, for example, the negative electrode terminal tab 54 may be electrically connected directly to the lid member 20, or the negative electrode terminal tab 54 and the lid member 20 may be electrically connected via a conductor equivalent to a lead wire (not shown). When conducting the positive electrode 40 to the current collector 61, for example, the positive terminal tab 44 may be electrically connected directly to the current collector 61 through the through hole 13 of the container body 10, or a conductor equivalent to a lead wire (not shown) connecting the positive terminal tab 44 and the current collector 61 may be placed inside the through hole 13 to electrically connect the positive terminal tab 44 and the current collector 61.

[0086] (Action of secondary batteries) 1 and 2, in the secondary battery 1 configured as described above, the lid member 20 functioning as an external connection terminal for the negative electrode is exposed to the outside, and the current collector plate 61 functioning as an external connection terminal for the positive electrode is exposed to the outside. Therefore, electrical connection to the outside can be made through the lid member 20 and the current collector plate 61, and the secondary battery 1 can be used.

[0087] In particular, according to the secondary battery 1 of this embodiment, as shown in FIG. 3, the peripheral wall portion 12 and the flange portion 21 are welded together, thereby combining the container body 10 and the lid member 20 into one body, and therefore the storage space 4 in which the electrode body 30 is housed can be properly sealed. Moreover, as is clear from the laser welding marks 9 formed on the upper surface 21b of the flange portion 21 (see FIG. 1), the container body 10 and the lid member 20 are welded together by heating from the flange portion 21 side, rather than from the container body 10 side to which the current collecting plate 61 is welded via the sealant film 60. Therefore, it is possible to prevent the heat applied during welding (welding heat) from being transferred to the sealant film 60.

[0088] Therefore, the sealant film 60 is less susceptible to the effects of welding heat, and it is possible to prevent the sealant film 60 from being melted or plasticized due to an unintended temperature rise. This makes it possible to prevent problems such as peeling of the sealant film 60, and ensures reliable sealing of the accommodation space 4. This allows the current collector plate 61 to function as an external connection terminal for the positive electrode, and also makes it possible to provide a high-quality secondary battery 1 with high operational reliability.

[0089] As described above, the secondary battery 1 of this embodiment can provide reliable sealing. In particular, as shown in Fig. 3, the peripheral wall 12 of the container body 10 and the flange 21 of the lid member 20 are welded together via the weld metal layer 5, which allows the container body 10 and the lid member 20 to be firmly joined together, thereby improving the sealing of the storage space 4. 2, the current collecting plate 61 is disposed on the underside of the bottom wall 11, so that the current collecting plate 61 can be exposed over the entire surface. Therefore, the current collecting plate 61 can be effectively used as an external connection terminal for the positive electrode, making the secondary battery 1 easy to use and excellent in mountability.

[0090] (Secondary battery manufacturing method) Next, an example of a method for manufacturing the secondary battery 1 of the first embodiment will be briefly described below. In the first embodiment, the current collecting plate 61 and the bottom wall portion 11 are thermally welded together via the sealant film 60. However, the sealant film 60 may be, for example, a single synthetic resin layer, or may be formed by joining multiple synthetic resin layers. Furthermore, the sealant film 60 may be a sealing material made of an inorganic material such as ceramic or glass.

[0091] In the first and second manufacturing methods described below, as described above, a sealant film 60 is formed by thermally welding together a first sealant and a second sealant made of synthetic resin.

[0092] <First manufacturing method> First, a process is performed in which the first seal material is placed on the upper surface of the current collector plate 61 and the two are combined together by thermal welding. This results in a current collector plate assembly in which the current collector plate 61 and the first seal material are combined together. Simultaneously with, or before or after, this step is performed a step of overlapping the second seal material on the underside of the bottom wall portion 11 of the container body 10 and combining them together by thermal welding, thereby obtaining a container body assembly in which the container body 10 and the second seal material are combined together.

[0093] When the above-mentioned two steps are performed, the heat welding method may be heating by a heater, heating by irradiation with a laser beam, induction heating using high frequency waves, etc. By using these methods, heating can be performed locally and selectively in a shorter time than when each component is heated using a heater, and heat welding can be performed efficiently while suppressing the influence of heat on the first and second resin sealants.

[0094] In the case of laser beam irradiation, for example, after placing the first sealant on the current collector plate 61, a laser irradiator such as a fiber laser or YAG laser is used to irradiate the first sealant from above. At this time, the laser beam passes through the first sealant and is absorbed by the current collector plate 61, causing local heating of the current collector plate 61. As a result, the heat generated in the current collector plate 61 locally melts the first sealant, causing it to adhere closely to the current collector plate 61. In this way, the first sealant can be joined to the top surface of the current collector plate 61 in a state where it is overlapped with good adhesion.

[0095] The laser beam has an irradiation diameter of about several tens of micrometers and can be irradiated continuously or linearly as pulses. By irradiating the laser beam circumferentially in the annular area where the current collector plate 61 and the first sealant overlap, the current collector plate 61 and the first sealant can be thermally welded in a ring shape. By forming multiple such circumferential welded areas concentrically, sufficient welding strength can be obtained even with a small welding area. This reduces the thermal effects on the first sealant.

[0096] Furthermore, when induction heating is performed, for example, the first sealant is placed on the current collector plate 61, and then the electromagnetic waves to be used are irradiated from above. At this time, similar to irradiation with a laser beam, the current collector plate 61 is selectively heated and generates heat, and further, only the surface portion of the first sealant that contacts the current collector plate 61 melts locally and adheres to the current collector plate 61. Depending on the conditions of induction heating, not only may the current collector plate 61 generate heat, but the first sealant may also melt due to dielectric heating caused by the irradiation of the electromagnetic waves, and adhere to the current collector plate 61. In this way, the first sealant can be joined to the upper surface of the current collector plate 61 in a state where it is overlapped with good adhesion.

[0097] For induction heating, electromagnetic waves in the frequency bands of, for example, very low frequency (VLF) to centimeter frequency (SHF) can be used. Specifically, so-called microwaves in the frequency band of, for example, 300 MHz to 30 GHz can be used. In particular, by using an oscillator with a magnetron in the 2.45 GHz frequency band, the irradiation device can be constructed inexpensively. Furthermore, it is also suitable to use a coil-type device to irradiate electromagnetic waves in the frequency band of 10 to 500 kHz, particularly in the frequency band of 20 to 100 kHz used in electromagnetic induction heating cookers.

[0098] Similar to the heat welding between the current collector plate 61 and the first sealant, the container body 10 and the second sealant can also be heat welded by the above-mentioned method. Note that the adhesion between the current collecting plate 61 and the first sealant, and the adhesion between the container body 10 and the second sealant can be further improved by previously performing a surface treatment on the metal surfaces of the current collecting plate 61 and the container body 10, and the resin surfaces of the first sealant and the second sealant. Specifically, for example, an oxide film on the metal surface can be removed using electron beam irradiation or the like to create a clean surface. Furthermore, the resin surface can be modified and its properties adjusted using techniques such as electron beam irradiation or ozone oxidation. Furthermore, adhesion can be further improved by applying a primer to the surface-treated metal surface or resin surface beforehand and then carrying out the above-mentioned two-step heat welding.

[0099] After the above two steps are completed, the current collecting plate assembly and the container body 10 assembly are combined so that the first sealant and the second sealant overlap, and then a step of heat-welding the first sealant and the second sealant together is performed. This allows the current collecting plate 61 and the container body 10 to be combined together via the sealant film 60, which is the first sealant and the second sealant integrated by heat welding.

[0100] Simultaneously with, or before or after, the process of forming the electrode body 30 is carried out, and the process of setting the electrode body 30 in the container body 10 and pouring the electrolyte is carried out. Next, the process of assembling the lid member 20 so that it overlaps with the container body 10 is carried out. This allows the flange portion 21 to be overlapped from above with the upper opening edge of the peripheral wall portion 12 of the container body 10.

[0101] Finally, a step is performed in which, for example, a laser beam is irradiated from above the flange portion 21 to weld the peripheral wall portion 12 of the container body 10 and the flange portion 21 of the lid member 20 together over the entire periphery. By irradiating the flange portion 21 of the lid member 20 with a laser beam from above, it is possible to locally heat the flange portion 21 of the lid member 20 and the upper opening edge of the peripheral wall portion 12 of the container body 10, and to melt the first metal film 6 and the second metal film 7 together, as shown in FIG. 3 . Then, by solidifying the first metal film 6 and the second metal film 7 after they have fused together, it is possible to form a weld metal layer 5. As a result, it is possible to weld the peripheral wall portion 12 of the container body 10 and the flange portion 21 of the lid member 20 together around the entire periphery via the weld metal layer 5.

[0102] 1 and 2 can be obtained. At this time, laser welding marks 9 are formed on the upper surface 21b of the flange portion 21 due to the effect of heating caused by irradiating the flange portion 21 with a laser beam from above. Therefore, the presence of the laser welding marks 9 indicates that heating has been performed by irradiating the flange portion 21 with a laser beam from above.

[0103] As described above, heating is performed by irradiating the flange portion 21 with a laser beam from above, which is different from heating the container body 10 side to which the current collecting plate 61 is welded via the sealant film 60, and as described above, it is possible to prevent the welding heat from being transmitted to the sealant film 60. Therefore, it is possible to make the sealant film 60 less susceptible to the effects of the welding heat, and to prevent the sealant film 60 from being melted or plasticized. This prevents problems such as peeling of the sealant film 60, and ensures reliable sealing of the storage space 4.

[0104] The welding strength can be increased by increasing the irradiation intensity by narrowing the beam diameter of the laser beam, etc. Therefore, from the viewpoint of performing strong welding, it is preferable to increase the plate thickness of the lid member 20. When irradiating the laser beam, it is sufficient that the laser beam is irradiated from above onto the flange portion 21 of the lid member 20. For example, the laser beam may be irradiated directly downward from above the flange portion 21 of the lid member 20, or the laser beam may be irradiated diagonally downward from above the lid member 20 and on the battery axis O side, or the laser beam may be irradiated diagonally downward from above the lid member 20 and outside the container body 10.

[0105] Furthermore, when irradiating a laser beam using a pulsed laser, the output of the first pulse to be irradiated may not be stable. Therefore, when irradiating a laser beam over the entire circumference, it is preferable to irradiate the first irradiated pulse and the last irradiated pulse so that they overlap. In this case, if the pulses completely overlap, there is a risk of excessive welding. Therefore, it is preferable to irradiate the pulses with a shift so that the pulse overlap in the radial direction is small, for example. This makes it possible to avoid excessive welding.

[0106] Furthermore, when performing the above-described welding work, it is possible to perform laser welding while applying pressure from above, for example, which allows the container body 10 and the lid member 20 to be welded together more firmly, and makes it possible to seal the storage space 4 with high airtightness.

[0107] <Second manufacturing method> Next, a second manufacturing method will be described, which manufactures the secondary battery 1 in a different process order from the first manufacturing method. In this manufacturing method, the electrolyte is injected last using the through-hole 13 formed in the bottom wall portion 11.

[0108] In this manufacturing method, similar to the first manufacturing method, a process is carried out to form a current collector plate assembly in which a current collector plate 61 and a first sealing material are combined together, and a container body assembly in which a container body 10 and a second sealing material are combined together.

[0109] Simultaneously with, or before or after, the above-described steps, a step of forming the electrode body 30 is carried out, and a step of setting the electrode body 30 in the container body 10 is carried out. At this stage, the electrolyte solution has not yet been poured. Next, a process is performed in which the lid member 20 is combined with the container body 10 by overlapping it, and a process is performed in which, for example, a laser beam is irradiated from above the flange portion 21 to weld the peripheral wall portion 12 of the container body 10 and the flange portion 21 of the lid member 20 around the entire circumference.

[0110] As a result, as with the first manufacturing method, a weld metal layer 5 can be formed between the peripheral wall portion 12 of the container body 10 and the flange portion 21 of the lid member 20, and the peripheral wall portion 12 and the flange portion 21 can be welded together around the entire circumference via the weld metal layer 5.

[0111] After the above welding work is performed, the exterior body 2 is turned upside down so that the bottom wall portion 11 of the container body 10 faces upward, and then a step is performed in which the electrolyte is poured into the container body 10 through the through-hole 13 formed in the bottom wall portion 11. At this time, the electrolyte can be poured in a vacuum, for example. Finally, the current collecting plate assembly is combined with the container body assembly so that the first sealant and the second sealant overlap, and then a process of heat welding the first sealant and the second sealant together is performed. This allows the current collecting plate 61 and the container body 10 to be combined together and the through-hole 13 to be closed via the sealant film 60, which is the first sealant and the second sealant integrated by heat welding.

[0112] As a result, the secondary battery 1 shown in FIGS. 1 and 2 can be manufactured. In particular, according to the present manufacturing method, the electrolyte is injected after welding the container body 10 and the lid member 20, so the electrolyte is not affected by the welding process. This makes it easier to perform the welding work and also makes it easier to maintain the quality and characteristics of the electrolyte. Furthermore, even with this manufacturing method, the second sealant that has been heat-welded to the bottom wall 11 of the container body 10 in advance can be made less susceptible to the effects of welding heat when the container body 10 and the lid member 20 are welded together. Therefore, problems such as plasticization of the second sealant are less likely to occur before the second sealant is heat-welded to the first sealant. Therefore, even with this manufacturing method, a secondary battery 1 can be obtained in which the storage space 4 is sealed with high airtightness.

[0113] Alternatively, the first and second sealants may be welded together by ultrasonic welding, for example, instead of thermal welding. This method further reduces the amount of heat generated by welding compared to thermal welding. This method is therefore preferable because it can further maintain the quality and properties of the electrolyte.

[0114] (Modification of the first embodiment) In the above first embodiment, it is preferable that the weld metal layer 5 formed between the peripheral wall portion 12 of the container body 10 and the flange portion 21 of the lid member 20 has a melting point lower than that of the base metal (e.g., stainless steel) constituting the container body 10 and that of the base metal (e.g., stainless steel) constituting the lid member 20. In this case, the composition ratio, melting point, etc. of the weld metal layer 5 to be generated can be adjusted by the composition ratio and film thickness (plating thickness) of the first metal film 6 and the composition ratio and film thickness (plating thickness) of the second metal film 7. For example, the weld metal layer 5 may be a metal layer having a composition ratio containing Ni (nickel) as the main component and at least one metal selected from P (phosphorus), B (boron), and Au (copper). For example, the weld metal layer 5 may contain 85 to 99 wt % Ni and 1 to 15 wt % P, or 80 to 99 wt % Ni, 0 to 10 wt % P, and 1 to 20 wt % Au. When the weld metal layer 5 contains B, the melting point tends to be high, so the B content can be determined taking into consideration the melting points of the base metals that make up the container body 10 and the lid member 20.

[0115] Furthermore, in the first embodiment, the case where laser welding is performed has been described as an example, but the present invention is not limited to laser welding, and other methods such as ultrasonic welding, resistance welding such as seam welding, friction stir welding, etc. can also be used. Even in these cases, by applying heat from the flange portion 21 side, rather than from the container body 10 side to which the current collecting plate 61 is thermally welded via the sealant film 60, it is possible to achieve the same effects as in the first embodiment.

[0116] In particular, when performing seam welding, as shown in Figure 6, by pressing a roller electrode 65 against the corner P1 between the upper surface 21b and the outer peripheral surface of the flange portion 21 while passing current through it, it is possible to apply pressure and heat, and therefore the container body 10 and the lid member 20 can be firmly welded and joined via the weld metal layer 5 formed between the peripheral wall portion 12 and the flange portion 21.

[0117] Therefore, even seam welding is effective for the present invention. Moreover, when seam welding using a roller electrode 65 is employed, a pressing surface (welding mark according to the present invention) 66 with a tapered cross section is formed at a corner P1 between the upper surface 21b and the outer peripheral surface of the flange portion 21 of the lid member 20, as shown in Fig. 6, due to heating while pressing the roller electrode 65 against the corner. This pressing surface 66 is formed continuously around the entire circumference of the flange portion 21. Therefore, it is possible to easily determine whether heating has been performed from the flange portion 21 side based on the presence or absence of the pressing surface 66 formed on the flange portion 21 of the lid member 20.

[0118] Furthermore, when seam welding is performed, the lid member 20 may be configured so that the outer peripheral surface of the flange portion 21 is shifted radially inward from the outer peripheral surface of the peripheral wall portion 12 of the container body 10, as shown in FIG. Specifically, in a vertical cross-sectional view of the secondary battery 1, the lid member 20 is formed so that the inclination angle of a first imaginary line L1 relative to the battery axis O is smaller than the inclination angle of a second imaginary line L2 relative to the battery axis O. The first imaginary line L1 is an imaginary line connecting a corner P2 between the upper opening edge and the outer circumferential surface of the peripheral wall portion 12 and the lower end of the pressing surface 66. The second imaginary line L2 is an imaginary line that follows the surface of the pressing surface 66.

[0119] By configuring the lid member 20 in this manner, a portion of the molten metal formed when the first metal film 6 and the second metal film 7 are melted together during welding can be caused to flow around the outer circumferential surface of the flange portion 21 by surface tension. This allows the weld metal layer 5 to be formed not only between the peripheral wall portion 12 and the flange portion 21, but also to flow around the outer circumferential surface of the flange portion 21, thereby covering the outer circumferential surface of the flange portion 21. This further increases the welding strength between the container body 10 and the lid member 20.

[0120] When the weld metal layer 5 is formed to cover the outer peripheral surface of the flange portion 21, the pressing surface 66 is not necessarily required, and can be formed in a similar manner, for example, when the first metal film 6 and the second metal film 7 are heated by irradiating them with a laser beam. However, in the case of seam welding in which the pressing surface 66 is formed, it is easy to control the amount of the weld metal layer 5 that wraps around the outer peripheral surface of the flange portion 21.

[0121] Furthermore, for example, if the weld metal layer 5 is configured to have a lower melting point than the base metal constituting the container body 10 and the base metal constituting the lid member 20, it may be possible to form the molten metal layer 5 at a temperature that does not require the formation of welding marks (e.g., laser welding marks 9, pressing surfaces 66 formed by applying pressure and current to roller electrodes, etc.). Even in such cases, by employing the first and second manufacturing methods described above, it is possible to prevent problems such as peeling of the sealant film 60 due to welding heat, and to reliably seal the inside of the storage space 4.

[0122] Furthermore, in the first embodiment, as shown in FIG. 7, for example, the lid member 20 may be formed with a pressure relief hole 70 that passes through the lid member 20 in the vertical direction. The relief hole 70 is closed by a sealing portion 71. The sealing portion 71 may be, for example, a synthetic resin material formed to fill the relief hole 70, or may be a metal piece, metal wire, metal ball, or the like welded by various welding methods, brazing, or the like to fill the relief hole 70. When the sealing portion 71 is made of metal, it is preferably a low-melting point metal having a melting point lower than that of the lid member 20.

[0123] When forming the relief hole 70 in this manner, after the container body 10 and the lid member 20 are welded together and the electrolyte is poured into the container body 10, the relief hole 70 can be closed using the sealing portion 71 as the final step. As a result, even if the electrolyte is heated due to the effects of welding, for example, and the internal pressure of the exterior body 2 increases as a result, the internal pressure can be released through the relief hole 70. Therefore, the increase in internal pressure can be suppressed, and a high-quality secondary battery 1 can be manufactured.

[0124] (Second embodiment) Next, a second embodiment of the electrochemical cell according to the present invention will be described with reference to the drawings. In this second embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

[0125] As shown in FIG. 8, a secondary battery (electrochemical cell according to the present invention) 80 of this embodiment differs from the first embodiment in the shape of the lid member. The lid member 81 of this embodiment (second container according to the present invention) is formed in a circular shape when viewed from above, and is formed in the shape of a cylinder with a top, which has a top wall portion 82 arranged to face the bottom wall portion 11 of the container body 10 in the direction of the battery axis O across the electrode body 30, an inner peripheral wall portion 83 that is continuous around the entire outer periphery of the top wall portion 82 and extends upward from the top wall portion 82, and an annular flange portion 84 that extends radially outward from the upper end of the inner peripheral wall portion 83.

[0126] The inner peripheral wall 83 protrudes slightly upward beyond the peripheral wall 12 of the container body 10, and is disposed radially inside the peripheral wall 12 in a double overlapping state. The flange 84 extends radially outward from the upper end of the inner peripheral wall 83, and is welded to the upper open end of the peripheral wall 12 in a state overlapping from above around the entire periphery. Specifically, similarly to the first embodiment, the peripheral wall portion 12 and the flange portion 84 are welded together via the weld metal layer 5 formed between the peripheral wall portion 12 and the flange portion 84 .

[0127] (Action of secondary batteries) The secondary battery 80 of this embodiment configured as described above can also achieve the same effects as those of the first embodiment. In addition, during assembly, before welding, the lid member 81 can be fitted inside the peripheral wall 12 of the container body 10 in a fitting relationship such as an interference fit. Therefore, by welding the container body 10 and the lid member 81 together, the storage space 4 can be sealed with even higher airtightness.

[0128] In this embodiment, laser welding marks 9 (see Figure 1) are formed on the upper surface (opposing surface according to the present invention) 84b of the flange portion 84, which is located opposite to the lower surface (joining surface according to the present invention) 84a that is welded to the peripheral wall portion 12, as in the first embodiment.

[0129] (Third embodiment) Next, a third embodiment of the electrochemical cell according to the present invention will be described with reference to the drawings. In this third embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. In the first embodiment (and also in the second embodiment), a configuration has been described in which the current collecting plate 61 is welded to the bottom wall portion 11 of the container body 10 via a sealant film 60. In contrast to this, in the present embodiment, the current collecting plate is welded to the lid member via a sealant film.

[0130] 9 and 10, a secondary battery (electrochemical cell according to the present invention) 90 of this embodiment is configured by combining a cylindrical container body 10 having an outer casing 2 with a bottom, and a lid member 91 to which a current collector plate 61 is welded via a sealant film 60. Therefore, in this embodiment, the lid member 91 functions as a first container according to the present invention, and the container body 10 functions as a second container according to the present invention.

[0131] The container body 10 is formed in a bottomed cylindrical shape having a bottom wall portion 11 and a peripheral wall portion 12. However, the through-hole 13 in the first embodiment is not formed in the bottom wall portion 11. The peripheral wall portion 12 in this embodiment functions as a second joining wall according to the present invention.

[0132] The lid member 91 is formed in a circular shape when viewed from above, and is formed in a cylindrical shape with a top, including a top wall portion 92 arranged facing the bottom wall portion 11 of the container body 10 in the direction of the battery axis O, with the electrode body 30 sandwiched between them, and an inner peripheral wall portion 93 connected around the entire outer periphery of the top wall portion 92 and extending upward from the top wall portion 92.

[0133] The lid member 91 is disposed inside the peripheral wall 12 so that the top wall 92 is positioned lower than the upper opening edge of the peripheral wall 12 of the container body 10, and so that the upper opening edge of the peripheral wall 12 and the upper opening edge of the inner peripheral wall 93 are flush with each other. As a result, the inner peripheral wall 93 is welded and joined to the inside of the peripheral wall 12 of the container body 10 in a radially double-overlapping state. Therefore, the inner peripheral wall 93 of the lid member 91 functions as a first joining wall according to the present invention.

[0134] In this embodiment, a through-hole 94 that passes through the top wall 92 in the vertical direction is formed in the center of the top wall 92 of the lid member 91, coaxial with the battery axis O. The shape of the through-hole 94 is not particularly limited, but is formed, for example, in a circular shape when viewed from above.

[0135] As described above, the current collecting plate 61 is heat-welded to the top wall portion 92 in which the through-hole 94 is formed, via the sealant film 60. Specifically, the current collecting plate 61 is heat-welded to the upper surface of the top wall portion 92 via the sealant film 60, and is exposed upward over its entire surface. The sealant film 60 is formed in a ring shape surrounding the through hole 94 formed in the top wall portion 92, and is arranged so as to overlap the upper surface 21b of the top wall portion 92 while being coaxial with the battery axis O. In the illustrated example, the sealant film 60 is folded downward from the inner peripheral edge portion, and has a protective portion 60a that protects the inner peripheral surface of the through hole 94 formed in the top wall portion 92 over the entire circumference.

[0136] The current collecting plate 61 is formed in a circular shape in a plan view with a diameter smaller than the outer diameter of the sealant film 60, and is arranged coaxially with the battery axis O and overlapping the upper surface of the sealant film 60. In this way, the current collecting plate 61 closes the through-hole 94 from above.

[0137] In the exterior body 2 configured as described above, the peripheral wall portion 12 of the container body 10 and the inner peripheral wall portion 93 of the lid member 91 are welded and joined around the entire circumference in a radially double-overlapping state. Note that in this embodiment, the peripheral wall portion 12 and the inner peripheral wall portion 93 may be joined via a weld metal layer, or may be joined without a weld metal layer interposed therebetween.

[0138] When welding the peripheral wall portion 12 and the inner peripheral wall portion 93 together, the welding is performed by irradiating a laser beam or the like horizontally, for example, from the outside of the peripheral wall portion 12 of the container body 10 toward the peripheral wall portion 12, rather than from the side of the inner peripheral wall portion 93 to which the current collecting plate 61 is welded via the sealant film 60. 9, laser welding marks 9 are formed on an outer peripheral surface (opposing surface according to the present invention) 12b of the peripheral wall portion 12 located on the opposite side to an inner peripheral surface (joining surface according to the present invention) 12a welded to the inner peripheral wall portion 93. The laser welding marks 9 are formed continuously, for example, around the entire circumference of the peripheral wall portion 12.

[0139] Furthermore, in the secondary battery 90 of this embodiment, the current collector plate 61 can function as an external connection terminal for the negative electrode, and the container body 10 can function as an external connection terminal for the positive electrode. In this case, when conducting the negative electrode 50 to the current collector 61, for example, the negative terminal tab 54 may be electrically connected directly to the current collector 61 through the through hole 94 of the lid member 91, or a conductor equivalent to a lead wire (not shown) connecting the negative terminal tab 54 to the current collector 61 may be placed inside the through hole 94 to electrically connect the negative terminal tab 54 to the current collector 61. Similarly, when conducting the positive electrode 40 to the container body 10, for example, the positive electrode terminal tab 44 may be electrically connected directly to the container body 10, or the positive electrode terminal tab 44 and the container body 10 may be electrically connected via a conductor equivalent to a lead wire (not shown).

[0140] (Action of secondary batteries) Even in the secondary battery 90 of this embodiment configured as described above, as is clear from the laser welding marks 9 formed on the outer peripheral surface 12b of the peripheral wall 12, the container body 10 and the lid member 91 are welded together by heating from the peripheral wall 12 side of the container body 10, rather than from the lid member 91 side to which the current collector plate 61 is welded via the sealant film 60. Therefore, it is possible to prevent the heat applied during welding (welding heat) from being transferred to the sealant film 60.

[0141] Therefore, the secondary battery 90 of this embodiment can achieve the same effects as those of the first embodiment. In particular, since the peripheral wall portion 12 and the inner peripheral wall portion 93 are in surface contact over the entire periphery, welding heat is easily dispersed and is less likely to be transmitted to the sealant film 60. In this respect, it is possible to prevent problems such as the sealant film 60 becoming plasticized and peeling off.

[0142] (Modification of the third embodiment) In the third embodiment, as shown in Fig. 11, the peripheral wall 12 of the container body 10 may be formed so as to extend radially outward as it extends upward. In other words, the container body 10 may be formed so that the peripheral wall 12 gradually widens in diameter as it extends upward.

[0143] Specifically, as shown in FIG. 11, the peripheral wall portion 12 includes a first peripheral wall portion 12A that extends radially outward as it moves upward from the outer peripheral edge portion of the bottom wall portion 11, and a second peripheral wall portion 12B that further extends radially outward as it moves upward from the upper end portion of the first peripheral wall portion 12A.

[0144] 12, the first peripheral wall portion 12A is inclined at a first inclination angle θ1 with respect to a normal line N perpendicular to the bottom wall portion 11, and is formed so as to increase in diameter as it extends upward. The second peripheral wall portion 12B is inclined at a second inclination angle θ2 with respect to the normal line N that is larger than the first inclination angle θ1, and is formed so as to increase in diameter as it extends upward more than the first peripheral wall portion 12A. In this way, the container body 10 is formed into an inverted tapered cylindrical shape whose diameter increases in two stages upward by the first peripheral wall portion 12A and the second peripheral wall portion 12B.

[0145] 11, the lid member 91 has an inner peripheral wall portion 93 that extends radially outward as it extends upward from the outer peripheral edge of the top wall portion 92 in accordance with the shape of the second peripheral wall portion 12B, and is inclined at a second inclination angle θ2 with respect to the normal line N. As a result, the inner peripheral wall portion 93 is in contact with the second peripheral wall portion 12B without any gaps around the entire circumference. Therefore, the lid member 91 is welded to the inside of the second peripheral wall portion 12B in a state where the inner peripheral wall portion 93 overlaps twice in the radial direction.

[0146] The secondary battery 90 configured as described above can also achieve the same effects as those of the third embodiment. In addition, because the second peripheral wall portion 12B is inclined, when the lid member 91 is assembled to the container body 10, the lid member 91 can be assembled with the inner peripheral wall portion 93 overlapping the second peripheral wall portion 12B from above. This allows the lid member 91 to be supported using the second peripheral wall portion 12B. Therefore, welding can be performed while effectively suppressing misalignment of the lid member 91 relative to the container body 10, and the container body 10 and the lid member 91 can be welded and joined more accurately and appropriately.

[0147] Furthermore, since the first peripheral wall portion 12A of the container body 10 is inclined at the first inclination angle θ1, even when the container body 10 is formed by press working using a molding die or the like, the container body 10 can be easily released from the molding die, which can lead to improved manufacturing efficiency of the secondary battery 90.

[0148] (Fourth embodiment) Next, a fourth embodiment of the electrochemical cell according to the present invention will be described with reference to the drawings. In this fourth embodiment, the same components as those in the third embodiment are designated by the same reference numerals, and the description thereof will be omitted. In the third embodiment, the current collecting plate 61 is disposed on the upper surface side of the lid member 91, but in this embodiment, the current collecting plate 61 is disposed on the lower surface side of the lid member 91.

[0149] 13, in a secondary battery (electrochemical cell according to the present invention) 100 of this embodiment, a current collector 61 is welded to the lower surface of a lid member 91 via a sealant film 60. As a result, the current collector 61 is integrally combined with the lid member 91 so as to cover a through-hole 94 formed in the lid member 91 from below, and is disposed within the accommodation space 4. Therefore, the current collector 61 is partially exposed upward through the through-hole 94.

[0150] In this embodiment, electroless plating may be performed by introducing a plating solution inside the protective portion 60a of the sealant film 60. In this case, a metal plating film (not shown) can be formed on the portion of the current collector plate 61 that is exposed to the outside, thereby improving the electrical connectivity with the external connection terminal, durability, etc.

[0151] (Action of secondary batteries) The secondary battery 100 of this embodiment configured as described above can also achieve the same effects as those of the third embodiment. Even if the current collector 61 is disposed on the underside of the lid member 91, the current collector 61 can be partially exposed through the through-hole 94, so that the current collector 61 can function as an external connection terminal for the negative electrode. Therefore, the terminal portion of an external terminal (not shown) can be brought into contact with the current collector 61 in a non-contact state with the lid member 91, thereby electrically connecting the external terminal and the current collector 61, and the secondary battery 100 can be used.

[0152] The configuration in which the current collecting plate 61 is disposed on the housing space 4 side may be applied to the first to third embodiments described above, and may also be applied to other embodiments described below.

[0153] (Fifth embodiment) Next, a fifth embodiment of the electrochemical cell according to the present invention will be described with reference to the drawings. In this fifth embodiment, the same components as those in the third embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0154] As shown in FIG. 14, a secondary battery (electrochemical cell according to the present invention) 110 of this embodiment differs from that of the third embodiment in the shape of a lid member (first container according to the present invention) 111. The lid member 111 of this embodiment is formed so that the inner peripheral wall portion 93 extends downward from the outer peripheral edge of the top wall portion 92. The lid member 111 is arranged so that the top wall portion 92 is located above the upper opening edge of the peripheral wall portion 12 of the container body 10, and the inner peripheral wall portion 93 fits snugly inside the peripheral wall portion 12. In particular, the inner peripheral wall portion 93 is formed so as to extend to the vicinity of the bottom wall portion 11 of the container body 10. As a result, the entire inner peripheral wall portion 93 is welded to the inside of the peripheral wall portion 12 of the container body 10 in a state where it overlaps twice in the radial direction.

[0155] (Action of secondary batteries) The secondary battery 110 of this embodiment can also achieve the same effects as those of the third embodiment. In addition, because the peripheral wall 12 of the container body 10 and the inner peripheral wall 93 of the lid member 111 overlap each other over a wide area, the peripheral wall 12 and the inner peripheral wall 93 can be easily welded together, and the welding points can be easily selected over a wide area in the direction of the battery axis O.

[0156] For example, by irradiating a laser beam near the upper end of the peripheral wall portion 12 as shown by arrow N1 in Figure 14, the peripheral wall portion 12 and the inner peripheral wall portion 93 can be welded together while forming laser welding marks 9 on the outer peripheral surface 12b on the upper end side of the peripheral wall portion 12 as shown in Figure 15. Furthermore, by irradiating a laser beam near the center of the peripheral wall portion 12 in the vertical direction as shown by arrow N2 in Figure 14, the peripheral wall portion 12 and the inner peripheral wall portion 93 can be welded together while forming a laser welding mark 9 near the center of the peripheral wall portion 12 in the vertical direction as shown in Figure 16. Furthermore, by irradiating a laser beam near the upper and lower ends of the peripheral wall portion 12 as shown by arrows N1 and N3 in Figure 14, it is possible to weld and join the peripheral wall portion 12 and the inner peripheral wall portion 93 at two locations, with laser welding marks 9 formed on the outer peripheral surface 12b on the upper and lower end sides of the peripheral wall portion 12, as shown in Figure 17.

[0157] Furthermore, when irradiating a laser beam using a pulsed laser, the output of the first pulse to be irradiated may not be stable. Therefore, when irradiating the laser beam over the entire circumference, it is preferable to irradiate the first irradiated pulse and the last irradiated pulse so that they overlap. In this case, if the pulses completely overlap, there is a risk of excessive welding. Therefore, it is preferable to irradiate the pulses with a shift so that the overlap of the pulses in the direction of the battery axis O is small. This makes it possible to avoid excessive welding.

[0158] As described above, according to the secondary battery 110 of this embodiment, the welding points can be selected arbitrarily over a wide range in the direction of the battery axis O, making the welding work easy to perform. In addition, it is also possible to weld the peripheral wall portion 12 and the inner peripheral wall portion 93 together at, for example, two or more locations, thereby increasing the welding joint strength and further improving sealing performance.

[0159] 14, in this embodiment, welding can be performed at a position away from the top wall portion 92 of the lid member 111 to which the current collecting plate 61 is welded via the sealant film 60, thereby increasing the heat transfer distance to the sealant film 60 and making it difficult for welding heat to be transferred to the sealant film 60. Therefore, welding heat is even more difficult to transfer to the sealant film 60, and problems such as peeling of the sealant film 60 can be more effectively prevented.

[0160] In this embodiment, when the laser beam is irradiated onto the outer peripheral surface 12b of the peripheral wall portion 12 during welding, it is not necessary to irradiate the entire circumference at the same height position. For example, the outer peripheral surface 12b of the peripheral wall portion 12 may be irradiated in a spiral (whorl) pattern. By irradiating the laser beam in this manner, the number of irradiations can be reduced to one, unlike when irradiation is performed multiple times along the container axis O. Therefore, particularly when irradiating with a pulsed laser, a laser beam with stable output can be continuously irradiated, allowing for stable welding. In this case, it is preferable not to simply irradiate the laser beam in a spiral shape, but to irradiate the laser beam so that at least one vertically elongated laser weld mark 9 is formed in an intersecting state across the spirally formed laser weld mark 9 in the direction of the battery axis O. At this time, the irradiation intensity of the laser beam may be temporarily reduced at the points where the spiral laser weld marks 9 and the vertically elongated laser weld marks 9 intersect, so as to prevent local excessive heating.

[0161] Furthermore, in this embodiment, the overlap between the peripheral wall 12 of the container body 10 and the inner peripheral wall 93 of the lid member 111 may be at least larger than the laser weld mark 9. This allows the overlap between the peripheral wall 12 and the inner peripheral wall 93 to be larger than the heat-affected zone (HAZ) caused by welding, thereby preventing the sealant film 60 from being disposed near the heat-affected zone. In this case, as shown in FIG. 14 , the peripheral wall 12 and the inner peripheral wall 93 do not necessarily need to overlap over the entire height of the battery (direction of the battery axis O). For example, the overlap may be approximately half the height of the battery, or even smaller. For example, as shown in FIG. 18 , the peripheral wall 12 of the container body 10 may be formed in a two-tiered cylindrical shape with a wider opening side, and the inner peripheral wall 93 of the lid member 111 may overlap the inside of the opening side (upper end side).

[0162] Also in this embodiment, as in the first embodiment, the current collector plate 61 and the container body 10 are disposed at the outermost positions in the vertical direction of the battery, as shown in Fig. 14. Therefore, when additional metal terminals are to be welded, flat terminals (linear in cross section) can be used, and even when the terminals are welded, an increase in the thickness of the battery in the vertical direction can be suppressed.

[0163] (Sixth embodiment) Next, a sixth embodiment of the electrochemical cell according to the present invention will be described with reference to the drawings. In this sixth embodiment, the same components as those in the third embodiment are denoted by the same reference numerals, and the description thereof will be omitted. In the third embodiment (and the other embodiments as well), the electrode body 30 has been described as an example of a laminated electrode in which positive electrodes 40 and negative electrodes 50 are wound flat so that they are alternately stacked in the direction of the battery axis O with a separator (not shown) sandwiched between them. In this embodiment, the battery includes an electrode body configured by being wound multiple times in the radial direction around the central axis of a support column that is arranged coaxially with the battery axis O.

[0164] As shown in FIG. 19, a secondary battery (electrochemical cell according to the present invention) 120 of this embodiment includes a support part 121 housed in the housing space 4 of the exterior body 2. The support pillar 121 is formed in the shape of a shaft extending in the vertical direction along the battery axis O, and is arranged coaxially with the battery axis O. In the example shown, the support pillar 121 is formed in the shape of a hollow cylinder, and its outer diameter is smaller than the diameter of the through-hole 94. As a result, the support pillar 121 is arranged so that its upper end contacts the current collector plate 61 from below through the through-hole 94, and its lower end contacts the bottom wall 11 of the container body 10 from above. Therefore, the support pillars 121 play a role in supporting the lid member 91 from below via the current collector plate 61 .

[0165] The support 121 is made of an insulating material such as an inorganic material, such as ceramic, or a synthetic resin material. When the support 121 is made of synthetic resin, for example, a thermoplastic resin having a melting point equivalent to that of the separator 131 can be suitably used. Specifically, synthetic resin materials such as PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), and LCP (liquid crystal polymer) can be used. Furthermore, copolymers and blend polymers of these synthetic resins can also be used.

[0166] (electrode body) As shown in FIG. 19, the electrode body 130 of this embodiment has a positive electrode 132 and a negative electrode 133 arranged with a separator 131 sandwiched between them, and is a wound electrode that is wound multiple times around a battery axis O. Specifically, the electrode body 130 is wound around the support part 121, with the positive electrode 132 and the negative electrode 133 overlapping each other with the separator 131 sandwiched between them, and is wound multiple times radially around the central axis C of the support part 121, which is arranged coaxially with the battery axis O. Therefore, the support part 121 of this embodiment also functions as a winding core when winding the electrode body 130.

[0167] The electrode body 130 is wound in a multiple spiral shape around the battery axis O (the central axis C of the support section 121) in a plan view seen from the direction of the battery axis O. In this embodiment, the electrode body 130 is wound so that the negative electrode 133, separator 131, positive electrode 132, separator 131, negative electrode 133, separator 131, and positive electrode 132 are repeatedly arranged in this order from the innermost layer located on the support section 121 side of the electrode body 130 to the outermost layer located on the peripheral wall section 12 side of the container body 10.

[0168] As shown in FIG. 20, the positive electrode 132 is formed in the shape of a single sheet, in the unfolded state before winding the electrode body 130, and includes a long positive electrode current collector (positive electrode current collector foil) 132a formed so as to extend in a strip shape with a constant width, and a positive electrode active material layer 132b formed by coating or the like on one or both sides of the positive electrode current collector 132a.

[0169] A positive electrode terminal tab 132c is formed on one end of the positive electrode current collector 132a that is located away from the support portion 121. The positive electrode terminal tab 132c does not have the positive electrode active material layer 132b formed thereon, and is capable of being electrically connected to other components. The positive electrode terminal tab 132c is disposed on the outer layer side of the electrode body 130 when the electrode body 130 is wound. The positive electrode current collector 132a and the positive electrode active material layer 132b can be made of the same materials as those in the first embodiment.

[0170] The negative electrode 133 is formed in the shape of a single sheet including a long negative electrode current collector (negative electrode current collector foil) 133a formed so as to extend in a strip shape with a constant width in the unfolded state before winding the electrode body 130, and a negative electrode active material layer 133b formed by coating or the like on one or both sides of the negative electrode current collector 133a.

[0171] A negative electrode terminal tab 133c is formed on one end of the negative electrode current collector 133a that is located away from the support portion 121. The negative electrode terminal tab 133c does not have the negative electrode active material layer 133b formed thereon, and is capable of being electrically connected to other components. The negative electrode terminal tab 133c is disposed on the outer layer side of the electrode body 130 when the electrode body 130 is wound. The negative electrode current collector 133a and the negative electrode active material layer 133b can be made of the same materials as those in the first embodiment.

[0172] 19 is formed of, for example, a microporous film made of a resin such as polyolefin, a nonwoven fabric made of glass or resin, or a laminate of fibers such as cellulose fibers, and is capable of passing lithium ions through ion permeable pores (not shown). Further, separator 131 may be, for example, a porous body capable of retaining an electrolyte solution in the pores, or a resin layer having lithium ion conductivity.

[0173] The separator 131 is disposed between the entire positive electrode 132 and the negative electrode 133, and insulates the positive electrode 132 from the negative electrode 133. Therefore, the separator 131 is disposed so as to be interposed between the positive electrode 132 and the negative electrode 133 at least in the entire region where the positive electrode 132 and the negative electrode 133 face each other.

[0174] The electrode body 130 configured as described above is wound around the support portion 121 as shown in FIG. 19, whereby it is combined integrally with the support portion 121 and becomes a wound electrode in which the positive electrode 132 and the negative electrode 133 are wound around the central axis C of the support portion 121 so as to be stacked in multiple layers in the radial direction with the separator 131 sandwiched between them. Even when the electrode body 130 is configured in this manner, for example, the current collector plate 61 can function as an external connection terminal for the negative electrode, and the container body 10 can function as an external connection terminal for the positive electrode.

[0175] (Formation of electrode body) A brief description will be given below of a case where the electrode body 130 is formed using the support part 121 as a winding core. 20 , after preparing the separator 131, the positive electrode 132, and the negative electrode 133, the separator 131 is welded to the outer peripheral surface 12b of the support part 121. In this way, the welded part 134 formed by welding the outer peripheral surface of the support part 121 and the separator 131 to each other can be used as a positioning part, and the separator 131 can be positioned relative to the support part 121.

[0176] If the length of separator 131 is predetermined, a portion of separator 131 shifted from the center in the longitudinal direction toward region R1 where positive electrode 132 is overlapped is welded to the outer peripheral surface of support portion 121. This makes it possible to ensure that region R2 of separator 131 where negative electrode 133 is overlapped is larger than region R1 where positive electrode 132 is overlapped.

[0177] Next, as indicated by an arrow M in Fig. 20, the support part 121 is rotated around the central axis C. At this time, the support part 121 is rotated so that the region R2 of the separator 131 where the negative electrode 133 is to be superimposed is wound around the support part 121 first. Next, the separator 131 and the negative electrode 133 are overlapped so that the negative electrode 133 is inserted between the separator 131 that has been wound around the support part 121 in advance and the support part 121. At this time, the negative electrode 133 is inserted as indicated by arrow S in FIG. 21 until it abuts against the welded part 134. By further rotating the support part 121 in this state, the negative electrode 133 can be wound around the support part 121 in advance, and the negative electrode 133 can form the innermost layer of the electrode body 130.

[0178] Furthermore, the support part 121 is continuously rotated while overlapping the positive electrode 132 on the separator 131, to wind up the separator 131, the positive electrode 132, and the negative electrode 133. As a result, it is possible to produce an electrode body 130 wound up around the support part 121, as shown in FIG.

[0179] (Action of secondary batteries) Even in the case of the secondary battery 120 of this embodiment configured in this way, it is possible to achieve the same effects as those of the third embodiment. In addition, since the lid member 91 can be supported using the support portion 121, unintended deformation, such as the lid member 91 bending before welding, can be suppressed, and welding work can be performed while further suppressing misalignment of the lid member 91 relative to the container body 10.

[0180] Furthermore, after forming the electrode body 130 by winding, the electrode body 130 together with the support portions 121 can be housed in the container body 10. This allows the assembly work to be carried out efficiently, leading to improved productivity.

[0181] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. The embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The embodiments and their modifications include, for example, those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are equivalent.

[0182] For example, in each of the above embodiments, a secondary battery has been described as an example of an electrochemical cell, but the present invention is not limited to this case and may be applied to various types of electricity storage devices, such as an electric double layer capacitor or a lithium ion capacitor.

[0183] When the electrochemical cell is applied to an electric double layer capacitor, the positive and negative electrodes may be used as a pair of polarizable electrodes. In this case, the polarizable electrodes may be, for example, activated carbon powder obtained by activation treatment, mixed with a conductive additive and a binder, and molded by calendar roll pressing or powder compacting press. The press molding may also be performed by a die punch press. The electrolyte can be, for example, one in which a supporting salt such as a quaternary ammonium salt is dissolved in a non-aqueous solvent. It is also possible to mix the material into a slurry, which can then be coated, dried, and processed into an electrode. It is also possible to use polytetrafluoroethylene (PTFE) as a binder, knead and mold the material into a plate shape, and then bond the plate to a current collecting foil with a conductive paste to form an electrode.

[0184] When the electrochemical cell is applied to a lithium-ion capacitor, the polarizable electrode described above can be used for only one of the positive and negative electrodes, and an electrode for a lithium-ion battery can be used for the other electrode. The same electrolyte as that used in a lithium-ion battery can be used. In particular, the use of lithium titanate (LTO) as an electrode for a lithium-ion battery can improve current characteristics.

[0185] Furthermore, although examples of exterior bodies with different shapes have been described in the above embodiments, the shapes of the container body and lid member may be changed as appropriate. For example, an annular groove with a U-shaped cross section may be formed in the lid member to improve the rigidity of the lid member. Furthermore, the lid member may be formed in a cylindrical shape with a top.

[0186] Furthermore, in each of the above embodiments, the electrode body is not limited to a specific structure, and any known electrode body may be used as appropriate. For example, as shown in FIG. 22, an electrode assembly (laminated electrode assembly) 140 may be formed by stacking positive electrodes 142 and negative electrodes 143 in multiple layers in the direction of the battery axis O with separators 141 sandwiched between them. In the illustrated example, the electrode body 140 is formed by laminating 12 layers of positive electrodes 142 and 12 layers of negative electrodes 143. However, the number of layers is not limited to 12 and may be changed as appropriate.

[0187] 22 to 24, the positive electrode 142 is formed in the shape of a single sheet including a thin-film positive electrode current collector (positive electrode current collector foil) 142a formed in a D-shape in plan view and positive electrode active material layers 142b formed by coating or the like on both sides of the positive electrode current collector 142a. A part of the positive electrode current collector 142a is a positive electrode terminal tab 142c where the positive electrode active material layer 142b is uncoated, and protrudes outward.

[0188] Separator 141 is a sheet formed in a D-shape in plan view corresponding to the shape of positive electrode 142, and is arranged to sandwich positive electrode 142 from above and below. In this case, separator 141 is formed to be slightly larger than positive electrode 142. As a result, positive electrode 142 is sandwiched and protected from above and below by two separators 141. The positive electrode terminal tab 142c is disposed so as to protrude outward beyond the separator 141.

[0189] The negative electrode 143 is formed in the shape of a single sheet including a thin-film negative electrode current collector (negative electrode current collector foil) 143a formed in a D-shape in plan view corresponding to the shape of the positive electrode 142, and negative electrode active material layers 143b formed by coating or the like on both sides of the negative electrode current collector 143a. A part of the negative electrode current collector 143a is a negative electrode terminal tab 143c where the negative electrode active material layer 143b is uncoated, and protrudes outward.

[0190] The negative electrode 143 is formed to have a size equal to or slightly smaller than the separator 141. Therefore, the positive electrode 142 is formed to have a size smaller than the negative electrode 143. The positive electrode terminal tab 142c is arranged to protrude outward beyond the separator 141 and is arranged not to face the positive electrode terminal tab 142c in the up-down direction.

[0191] 22, the electrode assembly 140 is configured by alternately stacking 12 layers of positive electrodes 142 and negative electrodes 143 with separators 141 sandwiched therebetween. Furthermore, the multiple (12) positive electrode terminal tabs 142c and negative electrode terminal tabs 143c are arranged side by side along the battery axis O.

[0192] The positive electrode terminal tabs 142c are electrically connected to one another by being gathered together by, for example, welding, etc. Similarly, the negative electrode terminal tabs 143c are electrically connected to one another by being gathered together by, for example, welding, etc.

[0193] The electrode body 140 is placed in the accommodation space 4, with the positive electrode terminal tab 142c, for example, being electrically connected to the container body 10, and the negative electrode terminal tab 143c being electrically connected to the current collector plate 61. This allows the current collector plate 61 to function as an external connection terminal for the negative electrode, and the container body 10 to function as an external connection terminal for the positive electrode, allowing the secondary battery to be used.

[0194] Furthermore, as another electrode body, for example, as shown in FIG. 25, an electrode body 150 may be employed in which a positive electrode 152 and a negative electrode 153 formed in the shape of a thin disk are stacked in the direction of the battery axis O.

[0195] The positive electrode 152 is formed in the shape of a single sheet including a thin-film positive electrode current collector (positive electrode current collector foil) 152a formed in a ring shape in a plan view, and positive electrode active material layers 152b formed by coating or the like on both sides of the positive electrode current collector 152a. In the illustrated example, the positive electrode active material layer 152b is hatched in dots to make the drawing easier to see. The positive electrode active material layer 152b is formed on the positive electrode current collector 152a except for the inner peripheral edge portion 152c, thereby enabling current collection to be performed using the inner peripheral edge portion 152c of the positive electrode current collector 152a.

[0196] The negative electrode 153 is formed in the shape of a single sheet including a thin-film negative electrode current collector (negative electrode current collector foil) 153a formed in a ring shape in a plan view corresponding to the shape of the positive electrode 152, and negative electrode active material layers 153b formed by coating or the like on both sides of the negative electrode current collector 153a. In the illustrated example, the negative electrode active material layer 153b is hatched in dots to make the drawing easier to see.

[0197] The negative electrode 153 is formed so that its outer diameter is larger than that of the positive electrode 152 and its inner diameter is larger than that of the negative electrode 153. This allows the entire area of ​​the positive electrode active material layer 152b to face the negative electrode active material layer 153b in the direction of the battery axis O. The negative electrode active material layer 153b is formed on the negative electrode current collector 153a except for the outer peripheral edge portion 153c, thereby enabling current collection to be performed using the outer peripheral edge portion 153c of the negative electrode current collector 153a.

[0198] When using an electrode body 150 having a positive electrode 152 and a negative electrode 153 configured as described above, the electrode body 150 may be configured by stacking multiple layers (e.g., 12 layers) of the positive electrodes 152 and the negative electrodes 153 alternately, similar to the electrode body 140 shown in FIG. 22 .

[0199] In this case, the electrode body 150 is placed in the accommodation space 4, and is electrically connected to the container body 10, for example, by using the inner peripheral edge 152c of the positive electrode current collector 152a, and the outer peripheral edge 153c of the negative electrode current collector 153a is electrically connected to the current collector plate 61. This allows the current collector plate 61 to function as an external connection terminal for the negative electrode, and the container body 10 to function as an external connection terminal for the positive electrode, allowing the use of a secondary battery.

[0200] When forming the positive electrode 152, for example, the positive electrode active material layer 152b is formed on both sides of the positive electrode current collector 152a formed in the shape of a long sheet by coating or the like. Next, the sheet-like positive electrode current collector 152a is processed into a ring shape by punching or the like, and the positive electrode active material layer 152b is further trimmed and partially removed by laser processing or the like, thereby forming the positive electrode 152. The negative electrode 153 can also be formed in a similar manner.

[0201] 25 does not necessarily have to be formed in a ring shape, but may be formed in a disk shape. In this case, current collection can be performed by utilizing the central portion of the positive electrode current collector 152a. 25, when the positive electrode 152 is formed in a ring shape, the positive electrode active material layer 152b may be applied over the entire area of ​​the positive electrode current collector 152a, including the inner peripheral edge 152c of the positive electrode current collector 152a. Even in this case, for example, by combining a current collector rod so as to pierce the positive electrode 152, current can be collected from the positive electrode current collector 152a covered with the positive electrode active material layer 152b.

[0202] Furthermore, in the negative electrode 153 shown in FIG. 25, the negative electrode current collector 153a may be formed so as to have a negative electrode terminal tab, and the negative electrode active material layer 153b may be applied over the entire area of ​​the negative electrode current collector 153a excluding the negative electrode terminal tab.

[0203] Furthermore, in each of the above embodiments, examples of outer casings with different shapes have been described, but as long as the lid member can be welded to a container body formed in a bottomed cylindrical shape and the opening of the container body can be closed, the shapes of the container body and the lid member may be changed as appropriate. For example, the rigidity of the lid member may be improved by forming an annular groove with a U-shaped cross section in the lid member.Furthermore, the lid member may be formed in a cylindrical shape with a top.

[0204] Furthermore, in each of the above embodiments, the first and second containers constituting the exterior package, i.e., the container body and the sealing plate, do not necessarily have to be made of metal. For example, at least one of the container body and the sealing plate may be formed using a laminate film in which a metal layer made of stainless steel or the like and a film-like resin layer are laminated. Even in such a case, welding or other joining can be performed using the metal layer. [Explanation of symbols]

[0205] C: Center axis of support O…Battery axis 1, 80, 90, 100, 110, 120...Secondary battery (electrochemical cell) 2...Exterior body 4. Containment space 5...Weld metal layer 9...Laser welding marks (welding marks) 10...Container body (first container, second container) 11...Bottom wall 12... Peripheral wall portion of container body (first joint wall, second joint wall) 12a...Inner peripheral surface (joint surface) of peripheral wall portion 12b...Outer surface of peripheral wall portion (opposing surface) 13, 94...Through holes 20, 81... Lid member (second container) 21, 84...Flange portion of lid member (second joining wall) 21a, 84a...Underside of flange (joint surface) 21b, 84b...Top surface of flange portion (opposing surface) 30, 130, 140, 150...electrode body 40, 132, 142, 152...Positive electrodes 50, 133, 143, 153...Negative electrode 60...Sealant film (resin material) 61...Current collecting plate 66...Pressing surface (welding marks) 70...Relief hole 91, 111... Lid member (first container) 93...Inner peripheral wall portion of lid member (first joining wall)

Claims

1. an exterior body including a first container having a first joint wall and a second container having a second joint wall welded to the first joint wall and forming an accommodation space between the first container and the second container; an electrode assembly having a positive electrode and a negative electrode and accommodated in the accommodation space; a current collector plate welded to the first container via an insulating resin material and at least a portion of which is exposed to the outside, A welding mark is formed on the second joining wall, the first joining wall and the second joining wall are welded together via a weld metal layer formed between the first joining wall and the second joining wall, the first container is formed in a bottomed cylindrical shape having a bottom wall portion to which the current collecting plate is welded via the resin material, and a peripheral wall portion; the second container has a flange portion overlapping an upper end opening edge of the peripheral wall portion from above, and the opening of the first container is closed by welding the flange portion to the peripheral wall portion; The peripheral wall portion is the first joining wall, The flange portion serves as the second joining wall, The electrochemical cell is characterized in that the weld metal layer is formed between the upper opening edge of the peripheral wall portion and the flange portion.

2. 10. The electrochemical cell of claim 1, The electrochemical cell, wherein the weld mark is formed on an opposing surface of the second joint wall that is located on the opposite side to a joint surface welded to the first joint wall.

3. 3. The electrochemical cell according to claim 1 or 2, An electrochemical cell, wherein the weld metal layer has a melting point lower than that of a base metal constituting the first container and that of a base metal constituting the second container.

4. 4. The electrochemical cell according to claim 1, The weld metal layer is formed so as to wrap around the outer peripheral surface of the flange portion and cover the outer peripheral surface of the flange portion.

5. An exterior body comprising a first container having a first joint wall, and a second container having a second joint wall welded to the first joint wall and forming a storage space between the first container and the second container; an electrode assembly having a positive electrode and a negative electrode and accommodated in the accommodation space; a current collector plate welded to the first container via an insulating resin material and at least a portion of which is exposed to the outside, A welding mark is formed on the second joining wall, the first container is formed in a cylindrical shape with a top having a top wall portion to which the current collecting plate is welded via the resin material and a first peripheral wall portion, the second container is formed in a bottomed cylindrical shape having a bottom wall portion and a second peripheral wall portion welded to the outside of the first peripheral wall portion along the entire periphery, The first peripheral wall portion is the first joining wall, The second peripheral wall portion serves as the second joining wall, The electrochemical cell, wherein the weld marks are formed on an outer peripheral surface of the second peripheral wall portion.

6. 6. The electrochemical cell of claim 5, The electrochemical cell, wherein the weld mark is formed on an opposing surface of the second joint wall that is located on the opposite side to a joint surface welded to the first joint wall.

7. 7. The electrochemical cell according to claim 5 or 6, an electrochemical cell, wherein the first joint wall and the second joint wall are welded together via a weld metal layer formed between the first joint wall and the second joint wall;

8. 8. The electrochemical cell of claim 7, An electrochemical cell, wherein the weld metal layer has a melting point lower than that of a base metal constituting the first container and that of a base metal constituting the second container.

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