Manufacturing method of secondary battery

Abstract

To provide a manufacturing method of a secondary battery capable of reducing foil tearing during ultrasonic bonding between a collector foil part of a metal foil and a collector terminal.SOLUTION: A manufacturing method of a secondary battery includes steps of: fixing a first part 12a of a foil collecting part of an electrode laminate body 10 in which a plurality of metal foils 12 are collected by a foil collecting fixing member 1; fixing a second portion 12b of the foil collecting part on a tip side of the first part 12a by being sandwiched between a current collecting terminal 11 and an ultrasonic horn 2; and releasing the fixing by the foil collecting fixing member 1, and providing ultrasonic waves by the ultrasonic horn 2 to ultrasonically bond the second part 12b of the foil collecting part of the metal foil and the current collecting terminal 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a secondary battery. [Background technology]

[0002] A secondary battery is a battery that has, for example, a positive electrode current collector layer, an electrolyte layer, and a negative electrode current collector layer, and has the function of repeatedly discharging and charging electricity.

[0003] As a method for manufacturing a secondary battery, for example, Patent Document 1 discloses a secondary battery including an electrode group in which a separator and an electrode coated with a mixture layer so that a metal foil exposed portion is provided on one end side are laminated, and a current collector plate ultrasonically welded to the metal foil exposed portion, characterized in that a foil fixing portion that fixes the metal foils together is provided between the ultrasonic welded portion of the current collector plate and the mixture layer.The secondary battery in Patent Document 1 is said to be able to realize measures to prevent the generation and intrusion of metal dust that causes internal short circuits. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-125110 A Summary of the Invention [Problem to be solved by the invention]

[0005] For example, in the manufacturing method of the secondary battery described above, when a foil collecting section in which multiple metal foils are collected is fixed and a terminal is joined to the foil collecting section further forward than the fixed section, if ultrasonic waves are applied while the fixed section of the foil collecting section is fixed, foil breakage may occur near the fixed section of the foil collecting section.

[0006] This results in a decrease in the yield of non-defective secondary batteries, for example, and therefore requires improvement.

[0007] Therefore, an object of the present disclosure is to provide a method for manufacturing a secondary battery that can reduce foil breakage during ultrasonic bonding of a metal foil collecting portion and a current collecting terminal. [Means for solving the problem]

[0008] The present disclosure achieves the above object by the following means.

[0009] (Aspect 1) A method for manufacturing a secondary battery, comprising the steps of: Fixing a first portion of a foil collecting section in which a plurality of metal foils of the electrode laminate are collected with a foil collecting fixing member; a second portion of the foil collecting portion, which is located on the tip side of the first portion, is sandwiched between a current collecting terminal and an ultrasonic horn and fixed; and The fixing by the foil collecting fixing member is released, and then ultrasonic waves are applied by the ultrasonic horn to ultrasonically bond the foil collecting portion and the current collecting terminal. (Aspect 2) The method according to aspect 1, wherein the thickness of the current collecting terminal is 0.4 mm to 4 mm in the direction sandwiched between the current collecting terminal and the ultrasonic horn. [Effects of the Invention]

[0010] According to the method of the present disclosure for manufacturing a secondary battery, foil breakage can be reduced during ultrasonic bonding of the foil collecting portion of the metal foil and the current collecting terminal. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram illustrating a method for manufacturing a secondary battery according to the present disclosure. [Figure 2] FIG. 2 is a schematic diagram illustrating a method for manufacturing a secondary battery according to the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Secondary battery manufacturing method> The disclosed method for manufacturing a secondary battery includes: Fixing a first portion of a foil collecting section in which a plurality of metal foils of the electrode laminate are collected with a foil collecting fixing member; a second portion of the foil collecting portion, which is located on the tip side of the first portion, is sandwiched between a current collecting terminal and an ultrasonic horn and fixed; and releasing the fixing by the foil collecting fixing member, and then applying ultrasonic waves by the ultrasonic horn to ultrasonically bond the foil collecting part and the current collecting terminal; Includes.

[0013] According to the method of the present disclosure for manufacturing a secondary battery, foil breakage can be reduced during ultrasonic bonding of the foil collecting portion of the metal foil and the current collecting terminal.

[0014] 1 and 2 are schematic diagrams showing the method for manufacturing a secondary battery according to the present disclosure, but the present disclosure is not limited to this case.

[0015] In a conventional method for manufacturing a secondary battery, a first portion 12a of a foil collecting section in which multiple metal foils 12 are collected is fixed with a foil collecting fixing member 1 (FIG. 2(a)), and a second portion 12b, which is located closer to the tip of the first portion 12a, is sandwiched and fixed between a current collecting terminal 11 and an ultrasonic horn 2 (FIG. 2(b)). When ultrasonic waves are applied by the ultrasonic horn 2 to ultrasonically bond the second portion 12b of the foil collecting section to the current collecting terminal 11, foil tearing can occur in the portion of the metal foil 12 that comes into contact with the foil collecting fixing member (FIG. 2(c)).

[0016] In contrast, according to the present disclosure, foil breakage can be reduced during ultrasonic bonding of the metal foil collecting portion and the current collecting terminal.

[0017] Hereinafter, embodiments of the present disclosure will be described in detail. Note that the present disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present disclosure. In addition, in the description of the drawings, the same elements are given the same reference numerals, and duplicated descriptions will be omitted.

[0018] (Foil collection fixing process) In the method of the present disclosure, first, a first portion of a foil collecting section in which a plurality of metal foils of an electrode laminate are collected is fixed with a foil collecting fixing member.

[0019] 1(a) shows a cross section of a structure used in manufacturing a secondary battery using the method of this embodiment. An electrode laminate 10 has an exposed portion of a metal foil 12 at one end thereof. A plurality of metal foils 12 are collected together and fixed at a first portion 12a of the collecting portion of the metal foils 12 by a foil collecting fixing member 1.

[0020] There are no particular limitations on the shape of the foil collecting fixing member 1. For example, in the foil collecting fixing member 1 shown in Fig. 1, the portion that comes into contact with the metal foil 12 has a curved surface, but the shape is not limited to this.

[0021] (joint fixing process) In the method of the present disclosure, next, a second portion of the foil collecting part, which is closer to the tip end than the first portion, is sandwiched and fixed between a current collecting terminal and an ultrasonic horn.

[0022] 1(b) shows a cross section of the structure used in manufacturing a secondary battery using the method of this embodiment. Of the foil collection part of the metal foil 12, the second part 12b, which is located closer to the tip than the first part 12a, is sandwiched and fixed between the ultrasonic horn 2 and the current collecting terminal 11.

[0023] (Ultrasonic bonding process) In the method of the present disclosure, next, the fixing by the foil collecting fixing member is released, and then ultrasonic waves are applied by the ultrasonic horn to ultrasonically bond the foil collecting portion and the current collecting terminal.

[0024] 1(c) shows a cross section of the structure used in manufacturing a secondary battery using the method of this embodiment. The foil collecting fixing member 1 is released, and then ultrasonic waves are applied by the ultrasonic horn 2. This bonds the second portion 12b of the foil collecting portion of the metal foil 12 and the current collecting terminal 11 to each other.

[0025] <Each configuration> Each component used in the method of the present disclosure will be described below.

[0026] (electrode laminate) In the present disclosure, the electrode stack may be a liquid-based electrode stack or a solid-state electrode stack. In the context of the present disclosure, a "solid-state battery" refers to a battery that uses at least a solid electrolyte as the electrolyte, and thus a solid-state battery may use a combination of a solid electrolyte and a liquid electrolyte as the electrolyte. The solid-state battery of the present disclosure may also be an all-solid-state battery, i.e., a battery that uses only a solid electrolyte as the electrolyte.

[0027] In the present disclosure, the electrode laminate is not particularly limited, and may have at least a positive electrode current collector layer, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer in this order. The electrode laminate may be, for example, a plurality of sub-electrode laminates, each of which has a positive electrode current collector layer, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer stacked in this order, with the positive electrode current collector layer and / or the negative electrode current collector layer being shared between adjacent sub-electrode laminates.

[0028] (metal foil) In the present disclosure, the metal foil extends from the electrode stack, and a plurality of metal foils are gathered to form a foil gathering portion. The number of metal foils is not particularly limited. Furthermore, examples of the material of the metal foil on the positive electrode current collector side include, but are not limited to, an aluminum alloy, and examples of the material of the metal foil on the negative electrode current collector side include, but are not limited to, a steel alloy.

[0029] (Current collector terminal) In the present disclosure, the current collecting terminal is a member that is ultrasonically bonded to the foil collecting portion. The current collecting terminal may be used to extract electricity generated in the electrode laminate to the outside. In the present disclosure, the thickness of the current collecting terminal refers to the thickness in the direction in which the current collecting terminal is sandwiched between the current collecting terminal and the ultrasonic horn. The thickness of the current collecting terminal is not particularly limited, but may be 1 mm or more, 2 mm or more, or 3 mm or more, or 13 mm or less, 12 mm or less, or 11 mm or less.

[0030] The shape and material of the current collecting terminals are not particularly limited, and metals such as aluminum and stainless steel (SUS) can be used as the material of the current collecting terminals.

[0031] (ultrasonic horn) In the present disclosure, the ultrasonic horn may be any member that can sandwich and fix the metal foil collecting portion between itself and the current collecting terminal, and that can apply ultrasonic waves to the metal foil to ultrasonically bond the foil collecting portion and the current collecting terminal. Examples of materials for the ultrasonic horn include, but are not limited to, metals such as aluminum and titanium.

[0032] The present disclosure will be described in more detail with reference to the following examples, but the scope of the present disclosure is not limited to these examples. [Example]

[0033] Comparative Example 1 The first portions of the metal foils of the electrode laminate were fixed with a foil collecting and fixing member. Furthermore, the second portions, which were closer to the tip of the first portions, were clamped and fixed between a current collecting terminal and an ultrasonic horn. A current collecting terminal with a thickness of 0.4 mm was used.

[0034] Next, ultrasonic waves were applied by an ultrasonic horn to ultrasonically bond the collecting portion of the metal foil to the current collecting terminal.

[0035] Finally, the first portion of the metal foil fixed by the foil collecting fixing member was released, and then the second portion of the metal foil fixed by the current collecting terminal and ultrasonic horn was released, thereby obtaining the electrode laminate of Comparative Example 1.

[0036] Comparative Example 2 An electrode laminate of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that the current collector terminal (0.4 mm thick) of Comparative Example 1 was replaced with a current collector terminal having a thickness of 4 mm.

[0037] Example 1 The first portions of the metal foils of the electrode laminate were fixed with a foil collecting and fixing member. Furthermore, the second portions, which were closer to the tip of the first portions, were clamped and fixed between a current collecting terminal and an ultrasonic horn. A current collecting terminal with a thickness of 0.4 mm was used.

[0038] Next, the first portion of the metal foil fixed by the foil collecting fixing member was released, and then ultrasonic waves were applied by the ultrasonic horn to ultrasonically bond the foil collecting portion of the metal foil and the current collecting terminal.

[0039] Finally, the current collecting terminal and the second portion of the metal foil fixed by the ultrasonic horn were released, and the electrode laminate of Example 1 was obtained.

[0040] Example 2 An electrode laminate of Example 2 was obtained in the same manner as in Example 1, except that the current collector terminal (thickness: 0.4 mm) of Example 1 was replaced with a current collector terminal having a thickness of 4 mm.

[0041] <Evaluation> The electrode laminates of Comparative Example 1, Comparative Example 2, Example 1, and Example 2 were compared in terms of foil breakage observed in the metal foil of the electrode laminate.

[0042] When the electrode laminates of Comparative Examples 1 and 2 and Examples 1 and 2 were compared, it was found that Examples 1 and 2 had significantly less foil breakage than Comparative Examples 1 and 2.

[0043] The foil breakage observed in the comparative example is thought to have occurred because the part of the metal foil that fixed the first part of the foil collecting part received a load from the foil collecting fixing member during ultrasonic bonding.

[0044] On the other hand, in the electrode laminates of Examples 1 and 2, it is believed that by releasing the first portion from its fixed position before applying ultrasonic vibrations, the load applied to the metal foil from the foil collecting fixing member during ultrasonic bonding was reduced, thereby reducing foil breakage. [Explanation of symbols]

[0045] 1 Foil collection fixing member 2 ultrasonic horns 10 Electrode laminate 11 Current collector terminal 12 Metal foil 12a First Section 12b Second Part

Claims

1. A method for producing a secondary battery, comprising the following steps: Fixing a first portion of a foil collecting section in which a plurality of metal foils of the electrode laminate are collected with a foil collecting fixing member; a second portion of the foil collecting portion that is closer to the tip end than the first portion is sandwiched between a current collecting terminal and an ultrasonic horn and fixed; The fixing by the foil collecting fixing member is released, and then ultrasonic waves are applied by the ultrasonic horn to ultrasonically bond the foil collecting portion and the current collecting terminal.

2. 2. The method according to claim 1, wherein the thickness of the current collecting terminal is 0.4 mm to 4 mm in the direction sandwiched between the current collecting terminal and the ultrasonic horn.

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