Lead member and nonaqueous electrolyte battery

Abstract

The invention relates to a lead member and a nonaqueous electrolyte battery. The present disclosure provides a lead member capable of reducing moisture infiltrating into the interior of a battery. A lead member provided with a flat conductor and an insulating film, the flat conductor having: a first main surface extending in a longitudinal direction and a width direction; a second main surface facing in a direction opposite to the first main surface; a first side surface connecting the first main surface and the second main surface at an end portion in the width direction; and a second side surface facing in a direction opposite to the first side surface, the insulating film is configured to cover a part of each of the first main surface, the second main surface, the first side surface and the second side surface of the flat conductor, and the insulating film is provided with a moisture-impermeable part.

Description

Technical Field

[0001] The present disclosure relates to a lead member and a nonaqueous electrolyte battery. Background Art

[0002] A lead member is used as a member for extracting electricity from a non-aqueous electrolyte battery. Patent Document 1 discloses a lithium ion battery tab that uses an adhesive film to improve adhesion to a packaging material.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2002-216741

[0006] If water penetrates into the battery, the battery will deteriorate. Therefore, the lead member is required to have moisture-impermeability to prevent penetration of water and moisture from the outside. Summary of the invention

[0007] An object of the present disclosure is to provide a lead member capable of reducing the amount of water that penetrates into a battery, and a nonaqueous electrolyte battery including the lead member.

[0008] The lead component disclosed herein is a lead component having a flat conductor and an insulating film, wherein the flat conductor has: a first main surface extending in a length direction and a width direction; a second main surface facing a direction opposite to the first main surface; a first side surface connecting the first main surface and the second main surface at an end in the width direction; and a second side surface facing a direction opposite to the first side surface, the insulating film being configured to cover a portion of each of the first main surface, the second main surface, the first side surface, and the second side surface of the flat conductor, and the insulating film having a non-moisture-permeable portion.

[0009] Effects of the Invention

[0010] According to the present disclosure, it is possible to provide a lead member capable of reducing the amount of moisture that intrudes into a battery, and a nonaqueous electrolyte battery including the lead member. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a perspective view of a lead member according to one embodiment of the present disclosure.

[0012] Figure 2 This is a perspective view showing an example of a non-aqueous electrolyte battery including a lead member according to an embodiment of the present disclosure.

[0013] Figure 3 yes Figure 2 Sectional view taken along the III-III direction.

[0014] Figure 4 yes Figure 2 Sectional view taken along the IV-IV direction.

[0015] Figure 5 This is a diagram for explaining an example of a method for evaluating the moisture permeability of a lead member.

[0016] Description of reference numerals:

[0017] 1: Lead component;

[0018] 2: Flat conductor;

[0019] 2a: first main surface;

[0020] 2b: second main surface;

[0021] 2c: first side;

[0022] 2d: second side;

[0023] 3: Insulation film;

[0024] 3a: first resin layer;

[0025] 3b: second resin layer;

[0026] 3c: Non-permeable part;

[0027] 10: Non-aqueous electrolyte battery;

[0028] 11: Sealed container;

[0029] 12: Sealing part;

[0030] 50: Test subject;

[0031] 51: film;

[0032] 51a, 51b, 51c, 51d: side view;

[0033] 52: Packaging material sheet;

[0034] 53: Dry materials. DETAILED DESCRIPTION

[0035] [Description of Embodiments of the Present Disclosure]

[0036] First, the embodiments of the present disclosure are listed for explanation. A lead component of one embodiment of the present disclosure is (1) a lead component having a flat conductor and an insulating film, wherein the flat conductor has: a first main surface extending in a length direction and a width direction; a second main surface facing a direction opposite to the first main surface; a first side surface connecting the first main surface and the second main surface at an end in the width direction; and a second side surface facing a direction opposite to the first side surface, the insulating film being configured to cover a portion of each of the first main surface, the second main surface, the first side surface, and the second side surface of the flat conductor, and the insulating film having a non-moisture-permeable portion.

[0037] In the lead member of (1) above, the insulating film has the moisture-impermeable portion, and therefore, the amount of moisture that penetrates through the insulating film into the battery can be reduced.

[0038] (2) In the above (1), the moisture impermeable portion may be made of an inorganic material.

[0039] Inorganic materials have particularly excellent moisture-impermeability, and thus can further reduce the amount of moisture that penetrates into the battery.

[0040] (3) In the above (1) or (2), it may be that, in at least one cross section of the flat conductor perpendicular to the longitudinal direction, the moisture impermeable area ratio expressed by the following formula (1) of a rectangular area defined by the width of the flat conductor and the thickness of the insulating film is greater than or equal to 10% and less than or equal to 90%.

[0041] Non-moisture permeable area ratio (%) = cross-sectional area of ​​the non-moisture permeable portion in the rectangular region / cross-sectional area of ​​the insulating film in the rectangular region × 100 (1)

[0042] The larger the cross-sectional area of ​​the moisture-impermeable portion in the insulating film, the narrower the path through which moisture in the insulating film can pass. When the moisture-impermeable area ratio is 10% or more, the moisture that penetrates into the battery can be further reduced. When the moisture-impermeable area ratio is 90% or less, it is easy to ensure the close adhesion of the conductor, the sealed container, and the lead member.

[0043] (4) A nonaqueous electrolyte battery according to one embodiment of the present disclosure includes the lead member according to any one of (1) to (3) above.

[0044] The nonaqueous electrolyte battery including the lead member described above reduces the amount of water that enters the battery, and thus has an excellent battery life.

[0045] [Details of the embodiments of the present disclosure]

[0046] Specific examples of the lead member and the nonaqueous electrolyte battery disclosed in the present invention are described below with reference to the drawings. It should be noted that the present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0047] (Lead member)

[0048] Figure 1 1 is a perspective view of a lead member 1 according to an embodiment of the present disclosure. In the following description, Figure 1 The X direction in the figure corresponds to the length direction, the Y direction corresponds to the width direction, and the Z direction corresponds to the thickness direction. The length direction, the width direction, and the thickness direction are directions perpendicular to the other two directions, respectively.

[0049] like Figure 1 As shown, the lead component 1 of this embodiment has a flat conductor 2 and an insulating film 3. The flat conductor 2 is plate-shaped and has: a first main surface 2a extending in the length direction and the width direction; a second main surface 2b facing in the direction opposite to the first main surface 2a; a first side surface 2c connecting the first main surface 2a and the second main surface 2b at the end in the width direction; and a second side surface 2d facing in the direction opposite to the first side surface 2c. The flat conductor 2 also has two side surfaces connecting the first main surface 2a and the second main surface 2b at the end in the length direction. It should be noted that Figure 1 In the figure, the rectangular conductor 2 is drawn as a rectangular parallelepiped, but the corners of the rectangular conductor 2 may be cut off or rounded. That is, the first side surface 2c and the second side surface 2d are not limited to being composed of only one plane, but may be composed of a plurality of planes and may include a curved surface.

[0050] The flat conductor 2 is a conductor for extracting electricity from the inside of the battery. The material of the flat conductor 2 is not particularly limited as long as it is a material used as a conductor of a lead member for a non-aqueous electrolyte battery. Examples of the material of the flat conductor 2 include metal materials such as aluminum, titanium, nickel, copper, aluminum alloys, titanium alloys, nickel alloys, and copper alloys, and materials obtained by plating any of these metal materials with nickel, gold, and the like.

[0051] The size of the rectangular conductor 2 is not particularly limited, and for example, the thickness may be 0.05 mm or more and 5.0 mm or less.

[0052] The insulating film 3 is used to prevent the flat conductor 2 from contacting the sealed container 11 (see Figure 2 ) short circuit. Figure 1As shown in FIG. 1 , the insulating film 3 is arranged to cover a portion of each of the first main surface 2a, the second main surface 2b, the first side surface 2c, and the second side surface 2d of the rectangular conductor 2. The insulating film 3 covers the first main surface 2a, the second main surface 2b, the first side surface 2c, and the second side surface 2d in the central portion of the rectangular conductor 2 except for both ends in the longitudinal direction. In the present embodiment, the insulating film 3 is composed of an insulating film covering a portion of the first main surface 2a and an insulating film covering a portion of the second main surface 2b, and the two insulating films are bonded to each other at the ends in the width direction of the lead member 1.

[0053] (Non-aqueous electrolyte battery)

[0054] Figure 2 1 is a perspective view showing a non-aqueous electrolyte battery 10 having a lead member 1 according to the present embodiment. The non-aqueous electrolyte battery 10 is configured by storing a stacked electrode group (not shown) in which a positive electrode plate and a negative electrode plate are stacked with a separator therebetween and an electrolyte solution in a sealed container 11, and sealing the sealed container 12 via the lead member 1 connected to the positive electrode plate and the negative electrode plate. Figure 2 In the nonaqueous electrolyte battery 10 shown, the lead member 1 connected to the positive electrode plate and the lead member 1 connected to the negative electrode plate are both lead members of one embodiment of the present disclosure, but the materials constituting the flat conductor 2 are different. The nonaqueous electrolyte battery 10 is configured to be sealed at the sealing portion 12 and to be able to electrically connect the inside of the battery with the outside of the battery via the flat conductor 2 of the lead member 1.

[0055] The sealed container 11 may be a container generally used as a packaging material for non-aqueous electrolyte batteries, and may be composed of, for example, a sheet body having resin layers disposed on both surfaces of a metal foil such as aluminum.

[0056] Figure 3 yes Figure 2 The cross-sectional view taken along line III-III in FIG. 1 is a view showing a cross section perpendicular to the width direction of the sealed lead member 1 . Figure 4 yes Figure 2 The cross-sectional view taken along line IV-IV in FIG. 1 is a view showing a cross section perpendicular to the longitudinal direction of the sealed lead member 1 .

[0057] (Resin layer)

[0058] like Figure 3 and Figure 4 As shown, in this embodiment, the insulating film 3 includes a first resin layer 3a and a second resin layer 3b. The first resin layer 3a is a resin layer in contact with the rectangular conductor 2, and the second resin layer 3b is a resin layer in contact with the sealed container 11. However, the insulating film 3 is not limited to a two-layer structure, and may have a structure of three or more layers.

[0059] The resin constituting the resin layer of the insulating film 3 is not particularly limited as long as it is a resin generally used for insulating films of lead members. Examples of the resin constituting the resin layer include polyolefin resins and acid-modified polyolefin resins, and more specifically, polyethylene, acid-modified polyethylene, polypropylene, and acid-modified polypropylene.

[0060] The thickness of the insulating film 3 is not particularly limited, and can be, for example, 50 μm or more and 300 μm or less. It is preferred that the insulating film 3 is thickened while the flat conductor 2 is enlarged to improve battery performance. On the other hand, when the insulating film 3 becomes thicker, the amount of moisture that penetrates into the battery from the outside through the insulating film 3 (resin layer) increases, which may cause battery degradation. However, as described later, the lead member 1 of the present embodiment reduces the penetration of moisture into the battery through the non-moisture-permeable portion 3c, so that the battery life can be maintained even if the insulating film 3 is thickened.

[0061] (Non-moisture-permeable part)

[0062] The insulating film 3 has a moisture impermeable portion 3c. In this embodiment, the moisture impermeable portion 3c is a metal plate disposed between the first resin layer 3a and the second resin layer 3b. Figure 3 As shown, the moisture impermeable portion 3c is disposed at a position interposed between the sealed containers 11 in the thickness direction.

[0063] The moisture-impermeable portion 3c is formed of a material having a lower moisture permeability than the first resin layer 3a and the second resin layer 3b constituting the insulating film 3. Organic materials such as nonwoven fabrics, and inorganic materials such as glass, metal, and ceramics can be used as the moisture-impermeable portion 3c. In particular, inorganic materials have excellent moisture-impermeability, and therefore, the moisture-impermeable portion 3c is preferably an inorganic material.

[0064] When the moisture impermeable portion 3c is made of metal, it is preferably covered with an insulating material to prevent electrical conduction between the moisture impermeable portion 3c and the rectangular conductor 2 or the sealed container 11. Specifically, a metal wire covered with an insulating resin may be used as the moisture impermeable portion 3c.

[0065] The shape of the non-moisture-permeable portion 3c is not particularly limited, and can be a plate-like shape, a cylindrical shape, a prism shape, a fibrous shape, etc. In the case of using a glass rod or a metal rod as an inorganic material, a cylindrical shape is preferred. In the case of using a non-woven fabric or a metal foil, for example, a material with a width of 10 μm or more and 10 mm or less can be used. In addition, the non-moisture-permeable portion 3c can also be composed of a plurality of non-moisture-permeable components.

[0066] The moisture impermeable portion 3c does not need to be arranged at the end of the insulating film 3 in any of the length direction, the width direction, and the thickness direction. In particular, it is preferable to arrange the resin layer at the end in the thickness direction instead of the moisture impermeable portion 3c. The innermost resin layer (the first resin layer 3a in this embodiment) and the outermost resin layer (the second resin layer 3b in this embodiment) of the resin layers constituting the insulating film 3 are respectively composed of materials having excellent adhesion to the rectangular conductor 2 and the sealed container 11. Therefore, the end of the insulating film 3 in the thickness direction is the resin layer, thereby ensuring excellent adhesion.

[0067] The method for manufacturing the insulating film 3 having the moisture impermeable portion 3c is not particularly limited and can be appropriately selected according to the configuration of the insulating film 3, the material and shape of the moisture impermeable portion 3c, etc. Figure 3 When the insulating film 3 shown has two resin layers (a first resin layer 3a and a second resin layer 3b), a method of laminating the sheets constituting the first resin layer 3a and the second resin layer 3b with a material constituting the moisture impermeable portion 3c sandwiched between the sheets constituting the first resin layer 3a and the second resin layer 3b can be cited. As another example of the method, a method of forming a resin layer by arranging extremely fine wires constituting the moisture impermeable portion 3c along the longitudinal direction of the resin material can be cited.

[0068] In the lead member 1 of this embodiment, the insulating film 3 has the moisture impermeable portion 3c, so the path through which moisture can pass from the outside of the battery to the inside of the battery through the insulating film 3 is blocked by the moisture impermeable portion 3c. Therefore, the moisture that penetrates into the battery through the insulating film 3 is reduced.

[0069] In such Figure 4 In the cross section perpendicular to the length direction of the flat conductor 2 shown in FIG. 1 , the larger the cross section area occupied by the moisture impermeable portion 3c, the narrower the path for moisture permeation. Specifically, the width of the flat conductor 2 and the thickness of the insulating film 3 (in FIG. 1 ) are determined by the following formula: Figure 4 The non-moisture permeable area ratio expressed by the following formula (1) of the rectangular area S defined by the length from the upper end of the second resin layer 3b on the upper side to the lower end of the second resin layer 3b on the lower side is preferably greater than 10% and less than 90%, more preferably greater than 20% and less than 80%, and further preferably greater than 30% and less than 70%.

[0070] Non-moisture permeable area ratio (%) = cross-sectional area of ​​the non-moisture permeable portion 3 c in the rectangular region S / cross-sectional area of ​​the insulating film 3 in the rectangular region S × 100 (1)

[0071] For example Figure 4 The moisture impermeable area ratio (%) of the rectangular region S in the is determined as follows.

[0072] Non-moisture permeable area ratio (%) = cross-sectional area of ​​the non-moisture permeable portion 3c in the rectangular region S / (cross-sectional area of ​​the first resin layer 3a in the rectangular region S + cross-sectional area of ​​the second resin layer 3b in the rectangular region S + cross-sectional area of ​​the non-moisture permeable portion 3c in the rectangular region S) × 100

[0073] (Evaluation method of moisture permeability)

[0074] As for the moisture permeability of the lead component 1, it is sufficient to evaluate the moisture permeability of the insulating film 3. Therefore, the moisture permeability of a film having the same resin layer and a non-moisture-permeable portion as the insulating film 3 is evaluated by the following method, thereby evaluating the moisture permeability of the lead component 1 having the insulating film 3.

[0075] Figure 5 : is a diagram showing the structure of a test body 50 for evaluating moisture permeability. A film of 200 mm in length and 200 mm in width is cut out from a resin sheet having the same resin layer and moisture impermeable portion as the insulating film 3, and then the inside is hollowed out to form a hollow square film 51. The film 51 is placed between two aluminum packaging material sheets 52 together with a drying material 53 such as silica gel, and the four sides of the packaging material sheet 52 are bonded to the film 51 by heat sealing. Thus, a test body 50 in which the drying material 53 is sealed inside and the side surfaces are sealed by the film 51 is obtained.

[0076] After measuring the mass of the test body 50 obtained by the above method, the mass of the test body 50 is measured again after the test body 50 is placed in a high temperature and high humidity environment for a predetermined period of time (for example, 24 hours at 80°C and 90% RH). When the test body 50 is placed in a high temperature and high humidity environment, the moisture that penetrates from the outside through the film 51 will be absorbed by the drying material 53, so the mass of the test body 50 will increase. Based on the measured mass of the test body 50, the water vapor permeability calculated by the following formula (2) becomes an indicator of the moisture permeability of the film 51, i.e., the insulating film 3. Among them, the "surface area of ​​the film 51" in formula (2) refers to the total surface area of ​​the portion of the film 51 exposed on the surface of the test body 50. For example, in Figure 5 In the test body 50 , the side surfaces 51 a , 51 b , 51 c , and 51 d of the film 51 are exposed on the surface. Therefore, the total area of ​​the side surfaces 51 a , 51 b , 51 c , and 51 d is the “surface area of ​​the film 51 ”.

[0077] Water vapor permeability (g / (m 2 = (mass of the test piece 50 after moisture absorption (g / 24H) - mass of the test piece 50 before moisture absorption (g / 24H)) / surface area of ​​the film 51 (m 2 )(2)

[0078] It should be noted that the thickness of the insulating film 3 of the lead member 1 is, for example, about 100 μm or more and 250 μm or less, but as the film 51 used for the above-mentioned evaluation, a thicker film may be used, and a plurality of films 51 may be overlapped for evaluation. In the method for evaluating moisture permeability, sometimes the mass change of the dry material is slight, sometimes the measurement error is large, or there is a need to extend the standing time. The moisture permeability of the insulating film 3 can be evaluated more quickly and accurately by increasing the surface area of ​​the film 51 used for evaluation in the test body 50.

[0079] [Example]

[0080] [Example 1]

[0081] Two hollow square polypropylene films with a thickness of 100 μm were prepared. A cylindrical glass wire with a diameter of 100 μm was used as a material constituting the non-moisture-permeable portion (hereinafter referred to as the non-moisture-permeable material). The glass wire was arranged in a quadrilateral on a polypropylene film so as to surround the hollow portion, and another polypropylene film was overlapped thereon to sandwich the glass wire. Next, the two polypropylene films were melted and integrated together with the glass wire, thereby obtaining a test film (film 51). The test film thus prepared was sandwiched with two aluminum packaging material sheets together with the dry material arranged in the hollow portion of the film, and the aluminum packaging material sheets were bonded by heat sealing to obtain a test body. The aluminum packaging material sheet was formed by stacking a polypropylene film (thickness 50 μm), an aluminum foil (thickness 30 μm), and a polyethylene terephthalate (PET) film (thickness 30 μm) in sequence from the side close to the test film, and each layer was bonded with an adhesive. The test piece thus obtained was left to stand at 80° C. and 90% RH for 24 hours, and the water vapor permeability was calculated from the increase in mass of the test piece.

[0082] [Example 2 to Example 5]

[0083] The test body was prepared in the same manner as in Example 1, except that the non-permeable material disposed between the polypropylene films was changed from glass yarn as shown in Table 1, and the water vapor permeability was calculated. The shape and diameter or thickness of the non-permeable material used in each example are shown in Table 1. In addition, the non-permeable material used in Example 4 was a non-woven fabric made of liquid crystal polymer (LCP) (the volume of the raw yarn in the non-woven fabric was 28.6%). The non-permeable material used in Example 5 was an inorganic paper with magnesium silicate as the main component (the volume of the raw yarn in the inorganic paper was 22.1%).

[0084] [Example 6]

[0085] A test piece was prepared in the same manner as in Example 1, except that two hollow square polypropylene films with a thickness of 100 μm were overlapped and welded without placing a moisture impermeable material between the two polypropylene films to obtain a test film, and the water vapor permeability was measured. The results are shown in Table 1.

[0086] The permeability reduction rates of Examples 1 to 5 in Table 1 are values ​​calculated by the following formula (3), and are indicators showing how much the water vapor permeability is reduced compared to the case where the moisture impermeable material is not used (Example 6).

[0087] Permeability reduction rate (%) = {1-(water vapor permeability of each example) / water vapor permeability of Example 6)}×100 (3)

[0088] [Table 1]

[0089] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 non-moisture-permeable material Glass Wire Alumina Copper Foil LCP Magnesium silicate - Shape of non-breathable material cylinder cylinder Flat Non-woven fabrics Non-woven fabrics - Diameter or thickness of non-permeable material (μm) 100 50 35 100 170 - <![CDATA[Water vapor permeability (g / (m 2 ·24H))]]> 16.1 23.0 24.0 27.3 25.0 28.3 Transmittance reduction rate 43.1％ 18.7％ 15.1％ 3.5％ 11.6％ -

[0090] In all of Examples 1 to 5, a decrease in water vapor permeability was observed.

Claims

1. A lead member comprising a flat conductor and an insulating film, wherein: The flat conductor comprises: a first main surface extending in the length direction and the width direction; a second main surface facing in the opposite direction to the first main surface; and a first side surface connecting the first main surface and the second main surface at an end in the width direction; and a second side surface facing in a direction opposite to the first side surface, The insulating film is arranged to cover a portion of each of the first main surface, the second main surface, the first side surface, and the second side surface of the rectangular conductor. The insulating film has a moisture impermeable portion.

2. The lead member according to claim 1, wherein The moisture impermeable portion is made of an inorganic material.

3. The lead member according to claim 1 or 2, wherein: In at least one cross section of the rectangular conductor perpendicular to the longitudinal direction, a moisture impermeable area ratio of a rectangular region defined by a width of the rectangular conductor and a thickness of the insulating film expressed by the following formula is 10% or more and 90% or less: Non-moisture permeable area ratio (%)=cross-sectional area of ​​the non-moisture permeable portion in the rectangular region / cross-sectional area of ​​the insulating film in the rectangular region×100. 4 . A non-aqueous electrolyte battery comprising the lead member according to claim 1 .

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