Battery manufacturing method and battery

Abstract

A method for manufacturing batteries that enables the stable production of highly reliable batteries by welding, even if the metal casing is thin-walled, and the provision of highly reliable batteries. [Solution] A battery manufacturing method and battery comprising the steps of: preparing a metal casing having an opening; housing an electrode body in the metal casing through the opening; and sealing the opening, wherein at least a portion of the opening is formed by a pair of edges of the metal casing, one of the pair of edges has a pair of bifurcated protruding pieces, and the step of sealing the opening includes welding at least one of the protruding pieces to the other edge with the other edge of the pair of edges sandwiched between the pair of protruding pieces.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a battery and a battery.

Background Art

[0002] For miniaturization of batteries, batteries have been developed that are manufactured by housing an electrode body in a metal exterior such as aluminum and sealing the opening by welding or the like.

[0003] When a power generation element is housed inside a metal outer casing having an opening and a joint portion where a metal lid is flush with the opening is joined by laser welding, in order to obtain a good welding state, with respect to the thickness t of the end face portion on the side irradiated with the laser light of either the opening or the lid and the laser beam focusing diameter D, a manufacturing method of a sealed battery is known in which the laser light is irradiated to the joint portion so that the relationship D / 2 < t holds (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Depending on the use of the battery or the like, further weight reduction and miniaturization of the battery may be required. In this case, it is required that the thickness of the metal exterior is thinner. However, when the thickness of the metal exterior is thin, welding the joint portion with laser light may cause adverse effects on internal electrodes or the like due to welding heat or the laser light itself. For example, it may be difficult to establish the relationship D / 2 < t, and it may be difficult to obtain a good welding state of the joint portion of the metal exterior (see Patent Document 1).

[0006] The problem that one embodiment of this disclosure aims to solve is to provide a battery manufacturing method that enables the stable production of highly reliable batteries by welding, even if the metal casing is thin-walled, and to provide a highly reliable battery even if the metal casing is thin-walled. [Means for solving the problem]

[0007] The means for solving the problem include the following: <1> A method for manufacturing a battery, comprising the steps of: preparing a metal casing having an opening; housing an electrode body in the metal casing through the opening; and sealing the opening, wherein at least a portion of the opening is formed by a pair of edges of the metal casing, one of the pair of edges has a pair of bifurcated protrusions, and the step of sealing the opening includes welding at least one of the protrusions to the other edge of the pair of protrusions while the other edge of the pair of edges is sandwiched between the pair of protrusions. <2> The process of preparing the metal casing includes welding a clamping member having a pair of protruding pieces to one edge. <1> The battery manufacturing method described above. <3> The process of preparing the metal casing includes forming the clamping members by impact pressing. <2> The battery manufacturing method described above. <4> At least one of the pair of protruding pieces has an inclined surface at its tip, and the step of sealing the opening includes sandwiching the other edge between the pair of protruding pieces while the inclined surface guides the other edge. <1> ~ <3> A method for manufacturing a battery as described in any one of the following. <5> A battery comprising a metal casing having a pair of edges and an electrode body housed in the metal casing, wherein one of the pair of edges has a pair of bifurcated protrusions, and the metal casing includes a welded portion formed by welding at least one of the protrusions to the other edge, with the other edge of the pair of protrusions sandwiched between the pair of protrusions. [Effects of the Invention]

[0008] According to one embodiment of the present disclosure, it is possible to provide a method for manufacturing a battery that can stably produce a highly reliable battery by welding, even if the metal casing is thin-walled. Furthermore, according to one embodiment of the present disclosure, it is possible to provide a highly reliable battery even if the metal casing is thin-walled. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a perspective view of a battery that is one embodiment of the present disclosure. [Figure 2] Figure 2 is a cross-sectional view along line AA in Figure 1, showing the battery, and illustrates a pair of bifurcated protrusions and one edge having them before the process of sealing the opening. [Figure 3] Figure 3 is a cross-sectional view along line AA in Figure 1, showing the battery, and illustrates a pair of bifurcated protrusions and one edge having them before the process of sealing the opening. [Figure 4] Figure 4 is an explanatory diagram illustrating a method for forming a pair of protruding pieces on one edge by welding. [Figure 5] Figure 5 is an explanatory diagram illustrating a method of forming a pair of protruding pieces on one edge by first forming a clamping member and then attaching the clamping member to one edge. [Figure 6] Figure 6 is a cross-sectional view along line AA in Figure 1, which shows the battery, and illustrates the welding process in the process of sealing the opening. [Modes for carrying out the invention]

[0010] In this disclosure, a numerical range indicated using "~" means a range that includes the numbers written before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. In the numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. When embodiments are described in this disclosure with reference to the drawings, the configuration of the embodiments is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each figure are conceptual, and the relative relationships between the components are not limited thereto. In addition, to avoid making the figures cluttered, multiple components that are substantially the same may only be partially labeled with reference numerals.

[0011] <Battery manufacturing method> A method for manufacturing a battery according to one embodiment of the present disclosure will be described below with reference to Figures 1 to 6. The method for manufacturing a battery according to one embodiment of the present disclosure comprises the steps of: preparing a metal casing having an opening (hereinafter also referred to as the metal casing preparation step); housing an electrode body in the metal casing (hereinafter also referred to as the electrode body housing step); and sealing the opening (hereinafter also referred to as the sealing step). At least a portion of the opening is formed by a pair of edges of the metal casing, and one of the pair of edges has a pair of bifurcated protruding pieces. The sealing step includes welding at least one of the pair of protruding pieces to the other edge with the other edge of the pair of protruding pieces sandwiched between the pair of protruding pieces.

[0012] In a battery that includes an electrode body and a metal casing that encloses the electrode body, when sealing a pair of edges of the metal casing that form an opening for housing the electrode body after housing the electrode body, butt welding may be considered from the viewpoint of welding stability. However, the thinner the metal casing, the lower the welding stability may be with butt welding. In addition, when welding after housing the electrode body in the metal casing, there are concerns about adverse effects on the electrode body due to welding heat and adverse effects on the electrode body due to laser light directly hitting the electrode body.

[0013] The thinner the metal outer package is, the smaller the heat capacity of the metal outer package becomes, and the sensitivity due to the welding heat of the metal outer package tends to increase, which may make welding difficult. Further, the thinner the metal outer package is, the lower the heat capacity of the metal outer package is, and since heat is likely to propagate from the welded portion, it is also conceivable that the adverse effect on the electrode body becomes greater. Also, in butt welding, it is difficult to completely eliminate the gap, and it is difficult to completely prevent the laser light from leaking inside at the welded portion.

[0014] The inventors of the present invention considered a method for more reliably sealing an opening in a good welding state and not giving an adverse effect due to heat or laser light to the electrode body when using a thin metal outer package, and focused on the shape of the object to be welded. Then, by making the shape of the object to be welded into a specific shape in which one sandwiches the other, even when a thin metal outer package is used, the opening can be more reliably sealed in a good welding state, and it has been found that the adverse effect due to heat or laser light on the electrode body is suppressed.

[0015] Although the mechanism by which the above effects are achieved is not clear, it is presumed that even if the metal forming the metal outer package is thin, due to the shape of the object to be welded, a structure including three or more members is formed between the welded portion and the electrode body.

[0016] (Metal outer package preparation step) The metal outer package preparation step is a step of preparing a metal outer package having an opening. The metal outer package can take various shapes according to the target battery, the electrode body to be housed, etc. Specifically, the metal outer package may be a metal outer package for a rectangular battery that is rectangular in plan view, or a metal outer package for a cylindrical battery.

[0017] The metal outer casing can be formed of a thin metal base material. As the metal base material, a metal foil that has been conventionally known and used as an outer casing of a battery can be adopted. Specifically, a metal base material containing aluminum, a metal base material containing stainless steel, etc. can be used. The thickness of the metal base material may be thin, preferably 1 mm or less, more preferably 0.2 mm to 0.5 mm, and even more preferably 0.3 mm to 0.5 mm.

[0018] The opening of the metal outer casing is an accommodation port for accommodating the electrode body in the metal outer casing. At least a part of the opening is formed by a pair of edge portions of the metal outer casing. The shape, size, etc. of the opening are not limited as long as the electrode body can be accommodated in the metal outer casing. When the metal outer casing has a configuration combining two members, a tray-shaped member and a lid-shaped member, the entire butting portion of the tray-shaped member and the lid-shaped member may be used as the opening, or a part of the entire butting portion may be welded in advance and the other part may be left unwelded to form the opening. Further, when the electrode body is accommodated by wrapping the electrode body with the thin metal base material constituting the metal outer casing, the opening may be formed by one edge portion and the other edge portion of the metal base material.

[0019] As shown in FIG. 1, a battery 10 according to an embodiment of the present disclosure is a rectangular battery that is rectangular in plan view. In the battery 10, the metal outer casing is formed by butting a tray-shaped member 11 and a lid-shaped member 12. A part of three sides of the butting portion where the tray-shaped member 11 and the lid-shaped member 12 are butted is adhered by welding before accommodating the electrode body, and one side of the butting portion is left as an opening without being adhered. The opening is formed by a pair of edge portions including the edge portion 13 (one edge portion) of the tray-shaped member 11 and the edge portion 14 (the other edge portion) of the lid-shaped member 12. The opening is sealed by welding. The battery 10 has a welded portion 15.

[0020] One of a pair of edges that form at least a portion of the opening has a pair of bifurcated protrusions. Of the pair of edges, one edge and the other edge may each have a pair of bifurcated protrusions. If one edge has a pair of protrusions, a portion of that edge may have a pair of protrusions, but from the viewpoint of manufacturing a highly reliable battery, it is preferable that the entire edge has a pair of protrusions.

[0021] As shown in Figure 2, one edge 13 that forms the opening has a shape having a pair of bifurcated protruding pieces 22. The pair of protruding pieces 22 are composed of a first protruding piece 22a and a second protruding piece 22b. Each of the pair of protruding pieces 22 has a shape corresponding to each of the pair of edges. In the case of a rectangular parallelepiped battery 10, each of the pair of protruding pieces 22 has a shape that extends in the longitudinal direction of the battery 10 corresponding to each of the pair of edges. When it becomes a battery 10, the first protruding piece 22a is located outside the metal casing, and the second protruding piece 22b is located inside the metal casing. Hereinafter, the protruding piece that is located outside the metal casing when it becomes a battery will be called the first protruding piece, and the protruding piece that is located inside the metal casing will be called the second protruding piece.

[0022] Because one edge has a pair of bifurcated protrusions, the other edge of the pair can be sandwiched between the pair of protrusions, allowing welding to be performed between at least one of the protrusions and the other edge, and welding can be performed with three or more members between the welding point and the electrode body. Furthermore, when sandwiching the other edge between the pair of protrusions, adhesive treatment such as brazing can be performed at the point where the other edge abuts against the pair of protrusions.

[0023] The shape of the pair of protruding pieces is not limited to any other shape, as long as the pair of protruding pieces can sandwich the edge of the other piece. Since one protruding piece functions as a welding point and the other protruding piece functions as a member that increases the heat capacity to prevent heat effects from welding, the shape may be such that each of these functions is more easily achieved.

[0024] For example, the first and second protruding pieces may have the same shape or different shapes. From the viewpoint of manufacturing a highly reliable battery by suppressing thermal history due to welding, one protruding piece may be formed thicker than the other. Specifically, depending on the shape of the electrode body, the second protruding piece can be made thicker than the first protruding piece based on the gap between the electrode body and the metal casing. Also, from the viewpoint of manufacturing a highly reliable battery by suppressing thermal history due to welding, the surface shape of one protruding piece may be different from the surface shape of the other protruding piece. Specifically, the surface of the second protruding piece facing the electrode body may be surface-treated to create irregularities. These irregularities may be formed by various surface treatments. This reduces the contact area with the electrode body and suppresses heat conduction. Furthermore, if the metal casing is thin-walled and highly sensitive to welding heat, the first protruding piece to be welded may be formed larger than the second protruding piece, and the second protruding piece may be formed smaller than the first protruding piece. In this case, the size can be the length of the protruding piece in the protruding direction. Furthermore, the materials of the first protrusion and the second protrusion may be different. The second protrusion may be formed from a material with lower thermal conductivity than the first protrusion, or it may be made of a foamed structure, or it may be made of multiple layers with air in between, or another component may be placed on the surface of the second protrusion.

[0025] Furthermore, it is preferable that at least one of the pair of protruding pieces has an inclined surface at its tip. The step of sealing the opening preferably includes the inclined surface guiding the other edge, thereby sandwiching the other edge between the pair of protruding pieces. This makes it easier to sandwich the other edge between the pair of protruding pieces. From the viewpoint of more reliably and easily sandwiching the other edge between the pair of protruding pieces, it is even more preferable that each of the protruding pieces of the pair has an inclined surface at its tip.

[0026] As shown in Figure 3, one edge 13 has a pair of protruding pieces 22. The first protruding piece 22a and the second protruding piece 22b, which are included in the pair of protruding pieces 22, have inclined surfaces 23a and 23b, respectively, at their tips. The thickness t2 of the second protruding piece 22b is greater than the thickness t1 of the first protruding piece 22a. The surface 24b of the second protruding piece 22b facing the electrode body has irregularities formed by surface treatment. The size of the first protruding piece 22a is larger than that of the second protruding piece 22b. That is, the length h1 of the first protruding piece 22a in the protruding direction is longer than the length h2 of the second protruding piece 22b in the protruding direction.

[0027] The method for forming a pair of protrusions on one edge is not limited to any method that does not require a pair of protrusions to be formed on one edge. Each of the pair of protrusions may be welded to one end.

[0028] As shown in Figure 4, a method for forming a pair of protruding pieces 22 on one edge 13 involves welding a first protruding piece 22a to the outer surface 31, which is the outside of the metal casing, at a weld joint 33a, and welding a second protruding piece 22b to the inner surface 32, which is the inside of the metal casing, at a weld joint 33b. In this case, from the viewpoint of manufacturing a highly reliable battery, it is preferable to set the welding point temperature to 600°C or higher and to perform the welding by laser welding.

[0029] A method for forming a pair of protruding pieces on one edge may be to pre-form a clamping member having a pair of protruding pieces and then bond the clamping member to one edge. From the viewpoint of manufacturing a highly reliable battery and reducing the number of steps, it is preferable that the step of preparing the metal casing includes welding the clamping member having a pair of protruding pieces to one edge.

[0030] The clamping member only needs to have a pair of protruding pieces and be able to be bonded to one edge; the method of formation is not limited. From the viewpoint of manufacturing a highly reliable battery and reducing the number of steps, it is preferable that the step of preparing the metal casing be in which the clamping member is formed by impact pressing.

[0031] As shown in Figure 5, when forming the clamping member 43 by impact press, the mold 41 forms the shape of the clamping member from the workpiece 42, which is the raw material for the clamping member 43. As an example of an impact press, since it is cold forging, it is formed at room temperature, and the press pressure is set to several tens to a hundred tons. The drive can be hydraulic. The mold holds and feeds the workpiece. The processing time, i.e., the processing speed, for forming the clamping member from the workpiece is preferably less than 1 second. The clamping member 43 is integrated by welding one edge 13 at the welded portion 44.

[0032] (Electrode housing process) The electrode housing process involves housing the electrode body in a metal casing through an opening. Various types of electrode bodies can be used depending on the intended battery. In addition to the electrode body, the metal casing can accommodate various components necessary for the battery, such as wiring and tabs.

[0033] (Sealing process) The sealing process is a process of sealing the opening. The sealing process includes welding at least one protruding piece to the other edge while the other edge of a pair of edges is sandwiched between a pair of protruding pieces. Since the first protruding piece, with the other edge of a pair of edges sandwiched between the pair of protruding pieces, is used as the welding point, even with thin-walled metal casings, welding is performed with multiple layers stacked on top of each other. This ensures more reliable welding, reduces adverse effects on the electrode body due to welding heat, and prevents the laser beam from directly hitting the electrode body. Furthermore, the sealing process can be implemented by a simple method such as sandwiching one edge forming the opening between the other edge.

[0034] In the process of sealing the opening, when the other edge of the pair of edges is sandwiched between the pair of protruding pieces, an adhesive treatment may be performed at the point where the other edge and the pair of protruding pieces abut. The adhesive treatment can be performed by welding, brazing, etc., and brazing is preferred because it allows for low-temperature processing and provides high adhesion. This allows for reliable sealing of the opening.

[0035] As shown in Figure 6, one example of sealing the opening by welding is to sandwich one edge 14 between the other edge 13 which has a pair of protruding pieces, and then laser-weld one of the pair of protruding pieces 22a at the welding location 51 using a laser head 52. The protruding pieces are formed by welding the sandwiching member 43 to one edge 13. The thickness of the protruding pieces (t1 and t2, see Figure 3) may be the same as the thickness of the metal base material forming the metal exterior, and for example, each is preferably 0.3 mm or more, and preferably 0.5 mm or more. Each of the protruding pieces 22 has a length of 5.0 mm in the protruding direction, and the welding location 51 is a location that is more than a distance d1 from the welded part 44 between the sandwiching member 43 and the other edge 13 in the protruding direction of the protruding piece. When the clamping member 43 is welded, the welding point 51 is preferably located at a distance of 0.5 mm or more from the welded portion 44 of the clamping member 43, more preferably at a distance of 1.00 mm or more, and even more preferably at a distance of 2.00 mm or more, from the viewpoint of its influence on the welding between the clamping member 43 and the other edge portion 13. In addition, brazing is performed as an adhesive treatment at the abutment portion 53 between the other edge portion 14 and the clamping member 43.

[0036] <Battery> A battery according to one embodiment of the present disclosure includes a metal casing having a pair of edges and an electrode body housed in the metal casing. One of the pair of edges has a pair of bifurcated protrusions. The metal casing includes a welded portion (welded portion 15, see Figure 1) formed by welding at least one of the protrusions to the other edge, with the other edge of the pair of protrusions sandwiched between the pair of protrusions.

[0037] The welded portion includes three or more components between the welded area and the electrode body. Therefore, since the heat capacity of the welded portion is increased, adverse effects on the electrode body due to welding heat are suppressed, resulting in a highly reliable battery. Furthermore, since one of the pair of edges is sandwiched between a pair of protruding pieces, the sealing of the opening can be made more reliable. In addition, when the other edge is sandwiched between the pair of protruding pieces, adhesive treatment can be performed at the point where the other edge and the pair of protruding pieces abut, thus making the sealing of the opening even more reliable. Therefore, a battery according to one embodiment of this disclosure is a highly reliable battery even if the electrode body metal casing is thin during manufacturing.

[0038] The type of battery in one embodiment of this disclosure is not limited to batteries in which a metal casing houses the electrode body, and may be either a liquid-based battery or a solid-state battery. Typically, it is a lithium-ion secondary battery, and can be selected from batteries such as lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, cobalt-titanium lithium secondary batteries, and sodium-ion secondary batteries. Solid-state batteries include semi-solid batteries, such as those having a gel layer containing an electrolyte and a polymer between the electrode and the solid electrolyte, and all-solid-state batteries that use a solid electrolyte as the electrolyte, with all-solid-state batteries being preferred. The battery in one embodiment of this disclosure is preferred because it is more effective when the electrode body is susceptible to heat, depending on the type of electrode, etc. Of course, it can also be used in batteries where the electrode body is not susceptible to heat. Therefore, the battery in one embodiment of this disclosure can use a wider range of materials as the electrode body material.

[0039] One embodiment of the battery described herein is preferably a high-capacity battery because the electrode material can be selected from a wider range of materials. Therefore, it is suitable for secondary batteries such as automotive solid batteries where high capacity is desired.

[0040] The applications of the battery, which is one embodiment of this disclosure, are not particularly limited. Typical applications include power sources for vehicles, electronic devices, and electrical storage systems. It may also be a high-capacity battery module containing multiple batteries. Among these, the battery of this disclosure is preferably used as a power source for vehicles. Examples of vehicles include electric four-wheeled vehicles, electric two-wheeled vehicles, gasoline automobiles, diesel automobiles, etc. Examples of electric four-wheeled vehicles include electric vehicles (BEV: Battery Electric Vehicle), plug-in hybrid electric vehicles (PHEV: Plug-in Hybrid Electric Vehicle), and hybrid electric vehicles (HEV: Hybrid Electric Vehicle). Examples of electric two-wheeled vehicles include electric motorcycles and electric assist bicycles. [Explanation of Symbols]

[0041] 10 batteries 11 Tray-shaped member 12 Lid-shaped member 13 One edge 14 The other edge 15. Welded section 22 Projecting piece 22a 1st protruding piece 22b Second protruding piece 23a, 23b Slope 24b surface t1, t2 thickness h1, h2 length d1 distance 31 External surface 32 Inner self 33a, 33b Welding locations 41 molds 42 Work 43 Clamping member 44 Welded section 51 Welding points 52 Laser Heads 53. Buttocks

Claims

1. A step of preparing a metal exterior body having an opening, The steps include: housing the electrode body in the metal casing through the opening; The process includes sealing the aforementioned opening, At least a portion of the opening is formed by a pair of edges of the metal exterior, One of the pair of edges has a pair of bifurcated protrusions, A battery manufacturing method comprising the step of sealing the opening, wherein the other edge of the pair of edges is sandwiched between the pair of protruding pieces, and at least one of the pair of protruding pieces is welded to the other edge.

2. The method for manufacturing a battery according to claim 1, wherein the step of preparing the metal casing includes welding a clamping member having a pair of protruding pieces to one of the edges.

3. The method for manufacturing a battery according to claim 2, wherein the step of preparing the metal casing is to form the clamping member by impact press.

4. At least one of the pair of projections has an inclined surface at its tip, The method for manufacturing a battery according to claim 1, wherein the step of sealing the opening includes the inclined surface guiding the other edge while sandwiching the other edge between a pair of protruding pieces.

5. It includes a metal casing having a pair of edges and an electrode body housed in the metal casing, One of the pair of edges has a pair of bifurcated protrusions, The battery includes a welded portion formed by welding at least one of the pair of protruding pieces to the other edge, with the other edge of the pair of protruding pieces sandwiched between the pair of protruding pieces.

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