Battery

Abstract

To provide a battery in which a laminate film is efficiently welded to a current collecting terminal even without preheating.SOLUTION: A battery discussed herein includes an electrode laminate, a current collecting foil extending from a side portion of the electrode laminate, a current collecting terminal electrically connected to the current collecting foil, and a laminate film that winds the electrode laminate and the current collecting terminal and seals the electrode laminate together with the current collecting terminal. In addition, the current collecting terminal that constitutes the battery disclosed herein has a bonding region that is bonded to the current collecting foil, and the bonding region has a contact portion that is in contact with the current collecting foil and a non-contact portion that is not in contact with the current collecting foil.SELECTED DRAWING: Figure 1

Description

Technical Field

[0006] , , , , ,

[0001] The present disclosure relates to a battery.

Background Art

[0002] A battery including an electrode laminate, a current collector terminal, and a laminate film that winds the electrode laminate and the current collector terminal and seals the electrode laminate together with the current collector terminal is known. In such a battery, it is normal to heat-seal the laminate film to the current collector terminal and then perform the above sealing. Regarding this, techniques for shortening the welding time during heat-sealing have been developed.

[0003] For example, Patent Document 1 discloses a method for manufacturing a secondary battery that pre-heats by pressing a current collector terminal with a heating element when heat-sealing a laminate film to the current collector terminal.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present disclosure is to provide a battery in which a laminate film is efficiently welded to a current collector terminal even when pre-heating is not performed.

Means for Solving the Problems

[0006] The present inventors have found that the above problems can be solved by the following means. 〈Aspect 1〉 An electrode laminate, A current collector foil extending from a side surface portion of the electrode laminate, A current collector terminal electrically connected to the current collector foil, and A laminate film is wound around the electrode laminate and the current collector terminal, sealing the electrode laminate together with the current collector terminal. A battery having, The current collection terminal has a bonding region that is joined to the current collection foil, and The bonding region has a contact portion that is in contact with the current collector foil and a non-contact portion that is not in contact with the current collector foil. battery. <Aspect 2> The current collection terminal has an uneven shape in the joining region, The contact portion is formed by joining the convex portion of the current collector terminal and the current collector foil, and The non-contact portion is formed by the fact that the concave portion of the current collector terminal and the current collector foil are not joined together. The battery described in Embodiment 1. <Aspect 3> The current collection terminal has a roughened surface treatment section in the joining region, The non-contact portion is formed by the fact that the roughened surface treatment portion and the current collector foil are not joined together. The battery described in Embodiment 1. <Aspect 4> The battery according to any one of embodiments 1 to 3, wherein the ratio of the area of ​​the contact portion to the area of ​​the bonding region is greater than 0.0 and less than 1.0. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a battery in which the laminate film is efficiently welded to the current collection terminal even without preheating. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic plan view illustrating a part of the battery of this disclosure. [Figure 2] Figure 2 is a schematic side view illustrating a part of the battery of this disclosure. [Figure 3] Figure 3 is a schematic side view illustrating a part of the battery of this disclosure. [Figure 4] Figure 4 is a schematic side view illustrating a part of the battery of this disclosure. [Figure 5] Figure 5 shows (a) a schematic side view illustrating a part of a conventional battery, and (b) a diagram showing how, in a conventional battery, when the laminate film is heat-sealed to the current collector terminal, the heat applied to the laminate film is transferred from the current collector terminal to the electrode laminate through the current collector foil. [Figure 6] Figure 6 is a graph showing the time it takes to reach the welding temperature when heat-welding a laminate film to a current collector terminal, using the current collector terminal for the battery of the present disclosure shown in Figure 2 (A in the figure) and the current collector terminal for the conventional battery shown in Figure 5 (B in the figure). [Modes for carrying out the invention]

[0009] The embodiments of this disclosure will be described in detail below. However, this disclosure is not limited to the embodiments described below, and can be implemented in various modified forms within the scope of the essence of the disclosure.

[0010] "battery" The battery of this disclosure comprises an electrode stack, a current collector foil extending from the side of the electrode stack, a current collector terminal electrically connected to the current collector foil, and a laminate film that wraps around the electrode stack and the current collector terminal, sealing the electrode stack together with the current collector terminal. Furthermore, the current collector terminal constituting the battery of this disclosure has a bonding region that is bonded to the current collector foil, and the bonding region has a contact portion that is in contact with the current collector foil and a non-contact portion that is not in contact with the current collector foil.

[0011] In a battery comprising an electrode stack, a current collector terminal, and a laminate film that wraps around the electrode stack and the current collector terminal to seal the electrode stack together with the current collector terminal, there is a problem in that the welding of the laminate film to the current collector terminal does not proceed efficiently. The Disclosers of this case believe that one of the causes of the above problem is that the heat applied to the laminate film for welding is transferred from the current collector terminal to the electrode stack through the part where the current collector terminal and the current collector foil are in contact.

[0012] That is, as shown in FIG. 5(a), when the current collector terminal 30 does not have the non-contact portion 120, as shown in FIG. 5(b), when the laminate film 40 is welded to the current collector terminal 30, the heat applied to the laminate film 40 by the heating element 200 is considered to move as shown by the arrow, that is, to move from the current collector terminal 30 through the current collector foil 20 to the electrode laminate 10.

[0013] Regarding this, the present inventors have found that by having a contact portion where the current collector terminal is in contact with the current collector foil and a non-contact portion where the current collector terminal is not in contact with the current collector foil, the laminate film can be efficiently welded to the current collector terminal even without preheating. Without intending to be bound by any theory, this is because the current collector terminal has the contact portion to ensure electrical conduction from the electrode laminate to the current collector terminal, and has the non-contact portion to suppress the heat transfer from the current collector terminal to the electrode laminate. Electricity It is considered that this is because the heat transfer from the current collector terminal to the electrode laminate can be suppressed by having the non-contact portion while ensuring electrical conduction.

[0014] Hereinafter, the battery of the present disclosure will be described with reference to FIG. 1. FIG. 1 is a schematic plan view illustrating a part of the battery when the battery in the present disclosure is viewed in plan from the stacking direction of the electrode laminate. Note that the dimensional relationships (length, width, thickness, etc.) in FIG. 1 and other drawings do not reflect the actual dimensional relationships.

[0015] As shown in FIG. 1, the battery 1 of the present disclosure includes an electrode laminate 10, a current collector foil 20 extending from a side surface portion of the electrode laminate 10, a current collector terminal 30 electrically connected to the current collector foil, and a laminate film 40 that winds the electrode laminate 10 and the current collector terminal 30 and seals the electrode laminate 10 together with the current collector terminal.

[0016] 〈Electrode laminate〉 The electrode stack 10 functions as a power generation element of the battery 1. The shape of the electrode stack 10 is not particularly limited, but for example, it has a top surface, a bottom surface opposite the top surface, and four side surfaces connecting the top surface and the bottom surface. The electrode stack 10 may also have a positive electrode current collector, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, and a negative electrode current collector in this order.

[0017] <Current collector foil> The current collector foil 20 extends from the side portion of the electrode laminate 10. The current collector foil 20 may be a bundle of portions of the positive electrode current collector in the electrode laminate 10 that do not have other layers laminated on them, and a bundle of portions of the negative electrode current collector in the electrode laminate 10 that do not have other layers laminated on them.

[0018] <Collector terminal> The current collector terminal 30 is electrically connected to the current collector foil 20. The material of the current collector terminal 30 is not particularly limited as long as it is a material that has a current collecting function, and for example, it can be the same metal material as the positive electrode current collector and the negative electrode current collector.

[0019] The current collector terminal 30 has a bonding region 100 that is joined to the current collector foil 20. The bonding region 100 has a contact portion 110 that is in contact with the current collector foil 20, and a non-contact portion 120 that is not in contact with the current collector foil 20. The bonding region 100 in the current collector terminal 30 is formed by connecting the contact portions 110 with straight lines so that it is the smallest area that includes all of the contact portions 110.

[0020] <Laminating film> The laminate film 40 wraps around the electrode laminate 10 and the current collector terminal 30, sealing the electrode laminate 10 together with the current collector terminal 30. The laminate film 40 may have a welding layer and a metal layer, and the welding layer can be welded to the current collector terminal 30. The material of the welding layer is not particularly limited as long as it is a material that can be welded to the current collector terminal, but for example, it may be a resin that can be heat-welded to the current collector terminal.

[0021] Figure 2 is a schematic side view illustrating a part of the battery 1 of the present disclosure. Figure 2 is a diagram showing the configuration of the current collector foil 20 and the current collector terminal 30 in cross-section AA of Figure 1. As shown in Figure 2, the current collector terminal 30 constituting the battery 1 of the present disclosure has an uneven shape in the joining region, and the contact portion 110 may be formed by joining the convex portion 111 of the current collector terminal 30 and the current collector foil 20, and the non-contact portion 120 may be formed by not joining the concave portion 121 of the current collector terminal 30 and the current collector foil 20.

[0022] One method for forming an uneven shape in the joining region of the current collection terminal 30 is to press-form the current collection terminal 30.

[0023] Figure 3 is a schematic side view illustrating a part of the battery 1 of the present disclosure. As shown in Figure 3(a), the current collector terminal 30 constituting the battery 1 of the present disclosure has a roughened surface treatment portion 130 in the bonding region, and the non-contact portion 120 may be formed by the fact that the roughened surface treatment portion 130 and the current collector foil 20 are not bonded together.

[0024] Furthermore, as shown in Figure 3(b), the current collector terminal 30 constituting the battery 1 of this disclosure may have a roughened surface treatment portion 130 in the bonding region, and the contact portion 110 may be formed by bonding the roughened surface treatment portion 130 and the current collector foil 20.

[0025] In other words, in the embodiment having a roughening treatment section 130, the portion corresponding to the contact portion 110 of the current collection terminal 30 may or may not be subjected to the roughening treatment.

[0026] The method for forming the roughened surface treatment area 130 in the joining region of the current collector terminal 30 is not particularly limited, and methods generally known for roughening metal surfaces can be used. Examples of such methods include mechanical treatments such as polishing, physical treatments such as laser irradiation, electrochemical treatments such as anodizing, and chemical treatments such as wet etching.

[0027] Figure 4 is a schematic side view illustrating a part of the battery 1 of this disclosure. As shown in Figure 4, even when using a current collector terminal 30 that has not been processed or treated on its surface, by preventing the current collector foil 20 from coming into contact with the current collector terminal 30 at any point other than the joint with the current collector terminal 30, the current collector terminal 30 can be made to have a contact portion 110 and a non-contact portion 120.

[0028] For example, by placing resin in the joining area of ​​the current collector terminal 30, and then joining the part without resin to the current collector foil 20, the resin can be removed or melted away to form a non-contact portion 120 on the current collector terminal 30.

[0029] In the above, an embodiment was described in which the non-contact portion is formed by a space provided between the current collector terminal and the current collector foil. However, the non-contact portion may be formed by a low thermal conductivity member placed between the current collector foil and the current collector terminal. That is, although not specifically shown, the current collector terminal may have a low thermal conductivity member placed in the joining region, the contact portion may be formed by joining the current collector foil with the portion where the low thermal conductivity member is not placed, and the non-contact portion may be formed by the low thermal conductivity member.

[0030] The low thermal conductivity material is not particularly limited as long as it has lower thermal conductivity compared to the materials constituting the current collector terminal and current collector foil, but resins are an example.

[0031] The ratio of the contact area to the bonding area (contact area / bonding area) may be greater than 0.0 and less than 1.0. This ratio may be 0.1 or more, 0.2 or more, 0.3 or more, or 0.4 or more, and may be 0.9 or less, 0.8 or less, 0.7 or less, or 0.6 or less. This ratio may also be 0.5. A small ratio is preferable from the viewpoint that when welding the laminate film to the current collector terminal, the heat applied to the laminate film is less likely to transfer from the current collector terminal to the electrode laminate through the current collector foil. A large ratio is preferable from the viewpoint that it facilitates bonding between the current collector foil and the current collector terminal.

[0032] The ratio of the contact area to the area of ​​the bonding region can be adjusted, for example, by controlling the area of ​​the concave portion and the area of ​​the roughened surface treatment portion.

[0033] The method for joining the current collector terminal and the current collector foil is not particularly limited, but an example of joining them using ultrasound is provided.

[0034] There are no particular limitations on the method for welding the laminate film to the current collector terminal, but a heat welding method is an example. In this method, the welding temperature can be determined by the melting point of the material used as the welding layer of the laminate film. The time to reach the welding temperature may be greater than 0 seconds, and may be less than 80 seconds, 70 seconds or less, or 60 seconds or less.

[0035] The battery in this disclosure may be a lithium-ion secondary battery. Examples of battery applications include powering vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), gasoline cars, and diesel cars. In particular, it is preferable to use it as a power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or battery electric vehicles (BEVs). Furthermore, the battery in this disclosure may be used as a power source for mobile devices other than vehicles (e.g., railways, ships, aircraft), or as a power source for electrical products such as information processing devices. [Examples]

[0036] 《Joining the current collection terminal and current collection foil》 <Example 1> A current collector terminal with the shape shown in Figure 2 was fabricated by press molding. The thickness of this current collector terminal from the bottom surface to the tip of the convex portion was 2 mm. In addition, a laminate of 30 sheets of 12 μm aluminum foil (A1050) was prepared as the current collector foil. The laminate of aluminum foil was placed on the current collector terminal and the current collector terminal and current collector foil were joined by ultrasonic bonding using a horn with a tip size of 1 mm. The distance between the joined parts was 2 mm. The ratio of the contact area to the area of ​​the joined area (contact area / joined area) was 0.5.

[0037] <Comparative Example 1> The current collector terminal and the current collector foil were joined in the same manner as in Example 1, except that a current collector terminal of the shape shown in Figure 5(a) was used. The ratio of the contact area to the area of ​​the joining region (contact area / joining region area) was 1.

[0038] "evaluation" The current collection terminals of each example were covered with a laminate film, and heat was applied to the laminate film. The time it took for the current collection terminals to reach the welding temperature of 160°C was measured. The welding layer material of the laminate film was polypropylene.

[0039] "result" The results of the evaluation described above are shown in Table 1 and Figure 6.

[0040] [Table 1]

[0041] As shown in Table 1 and Figure 6, in Example 1, which used an article in which a current collector terminal having a contact portion and a non-contact portion was joined to a current collector foil, the ratio of the contact portion area to the jointed area (contact portion area / jointed area) was 0.5, the time it took for the current collector terminal to reach the welding temperature was short. [Explanation of symbols]

[0042] 1 battery 10 Electrode Stack 20 Current collector foil 30 Current collector terminal 40 Laminating Films 100 joint area 110 Contact area 111 Convex part 120 Non-contact part 121 Concave part 130 Surface roughening treatment

Claims

1. Electrode stack, The current collector foil extending from the side portion of the electrode stack, A current collector terminal electrically connected to the current collector foil, and A laminate film is wound around the electrode laminate and the current collector terminal, sealing the electrode laminate together with the current collector terminal. A battery having, The current collection terminal has a bonding region that is joined to the current collection foil, The bonding region has a contact portion that is in contact with the current collector foil and a non-contact portion that is not in contact with the current collector foil. The ratio of the area of ​​the contact portion to the area of ​​the joining region is 0.3 or more and 0.7 or less. The current collection terminal has an uneven shape only in the joining region, The contact portion is formed by joining the convex portion of the current collector terminal and the current collector foil, and The non-contact portion is formed by the fact that the concave portion of the current collector terminal and the current collector foil are not joined together. battery.

2. Electrode stack, The current collector foil extending from the side portion of the electrode stack, A current collector terminal electrically connected to the current collector foil, and A laminate film is wound around the electrode laminate and the current collector terminal, sealing the electrode laminate together with the current collector terminal. A battery having, The current collection terminal has a bonding region that is joined to the current collection foil, The bonding region has a contact portion that is in contact with the current collector foil and a non-contact portion that is not in contact with the current collector foil. The ratio of the area of ​​the contact portion to the area of ​​the joining region is 0.3 or more and 0.7 or less. The current collection terminal has a roughened surface treatment section only in the joining region, and The non-contact portion is formed by the fact that the roughened surface treatment portion and the current collector foil are not joined together. battery.

3. Electrode stack, The current collector foil extending from the side portion of the electrode stack, A current collector terminal electrically connected to the current collector foil, and A laminate film is wound around the electrode laminate and the current collector terminal, sealing the electrode laminate together with the current collector terminal. A battery having, The current collection terminal has a bonding region that is joined to the current collection foil, The bonding region has a contact portion that is in contact with the current collector foil and a non-contact portion that is not in contact with the current collector foil. The ratio of the area of ​​the contact portion to the area of ​​the joining region is 0.3 or more and 0.7 or less, and In the current collector terminal whose surface is not processed, the non-contact portion is formed by a space provided between the current collector foil and the current collector terminal. battery.

4. Electrode stack, The current collector foil extending from the side portion of the electrode stack, A current collector terminal electrically connected to the current collector foil, and A laminate film is wound around the electrode laminate and the current collector terminal, sealing the electrode laminate together with the current collector terminal. A battery having, The current collection terminal has a bonding region that is joined to the current collection foil, The bonding region has a contact portion that is in contact with the current collector foil and a non-contact portion that is not in contact with the current collector foil. The ratio of the area of ​​the contact portion to the area of ​​the joining region is 0.3 or more and 0.7 or less. In the current collector terminal, which has no surface processing, the non-contact portion is formed by a low thermal conductivity member disposed between the current collector foil and the current collector terminal, and The contact portion is formed by joining the portion where the low thermal conductivity member is not placed with the current collector foil. battery.

5. The battery according to any one of claims 1 to 4, wherein the ratio of the area of ​​the contact portion to the area of ​​the bonding region is 0.4 or more and 0.6 or less.

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