Electrode tab, battery, and method for attaching electrode tab

Abstract

To provide an electrode tab capable of ensuring sufficient air tightness of a secondary battery even if the thickness of an electrode tab is increased to some extent.SOLUTION: An electrode tab can be mounted to a housing body for housing a battery element therein, and is configured to be electrically connected to an electrode of the battery element. The electrode tab includes a mounting portion configured to be mounted on the housing body. In a cross section of the mounting portion, the thickness of a central portion in the width direction is thicker than the thickness of an edge portion in the width direction. In the cross section of the mounting portion, a curve connecting at least a part between any point that corresponds to the central portion on an outer periphery and any point that corresponds to the edge portion on the outer periphery has at least one inflection point.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an electrode tab, a battery, and a method for attaching the electrode tab. [Background technology]

[0002] JP 2014-207069 A (Patent Document 1) discloses an electrode tab used in a laminated lithium-ion battery. The cross-sectional shape of this electrode tab is a shape in which both ends in the width direction are chamfered. With this electrode tab, the resin flows smoothly to the side of the electrode tab when the laminate film and the electrode tab are heat-sealed via the resin, so that good airtightness can be obtained in the completed laminated lithium-ion battery (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-207069 A Summary of the Invention [Problem to be solved by the invention]

[0004] Some secondary batteries such as lithium ion batteries and other primary batteries have electrode tabs that protrude outward from a housing that houses the battery element. In such batteries, the thickness of the electrode tabs used in these batteries generally increases as the maximum input / output power of the secondary battery or the maximum output power of the primary battery increases. Depending on the thickness of the electrode tab, the electrode tab disclosed in the above Patent Document 1 may not be able to sufficiently ensure the airtightness of the battery.

[0005] The present invention has been made to solve such problems, and its object is to provide an electrode tab that can sufficiently ensure the airtightness of a battery even if the thickness of the electrode tab becomes relatively large. [Means for solving the problem]

[0006] An electrode tab according to an aspect of the present invention is attachable to a housing that houses a battery element and configured to be electrically connected to an electrode of the battery element. The electrode tab includes an attachment portion configured to be attached to the housing. In a cross section of the attachment portion, the thickness of a central portion in the width direction is greater than the thickness of an end portion in the width direction. In a cross section of the attachment portion, a curve connecting at least a portion between any point on the outer periphery corresponding to the central portion and any point on the outer periphery corresponding to the end portion has at least one inflection point.

[0007] If the thickness of the electrode tab is abruptly thinned at the end in the width direction (if a large step is formed), sufficient adhesion is not achieved at that position, and the airtightness of the secondary battery may decrease. In the electrode tab according to the present invention, in the cross section of the mounting part, a curve connecting at least a part between any point on the outer periphery corresponding to the central part and any point on the outer periphery corresponding to the end has at least one inflection point. That is, in the cross section of the mounting part of the electrode tab, the thickness of the cross section is large and smoothly decreased in the region near the central part, and the thickness of the cross section is small and smoothly decreased in the region near the end. Therefore, according to this electrode tab, since the thickness does not rapidly decrease at the end in the width direction of the electrode tab, the electrode tab can be sufficiently adhered to the container even if the thickness of the electrode tab becomes thick to a certain extent, and the airtightness of the battery can be sufficiently ensured.

[0008] In the electrode tab, the housing may be in the form of a pouch, and the attachment portion may be configured to be attached to the housing in a state where it is sandwiched by the housing.

[0009] In the electrode tab, an adhesive member may be adhered to the surface of the attachment portion.

[0010] This electrode tab allows easy bonding of the housing and the electrode tab.

[0011] A battery according to another aspect of the present invention includes a battery element, a housing, and the above-mentioned electrode tab. The housing houses the battery element. The electrode tab is attached to the housing and is electrically connected to an electrode of the battery element. A recess is formed on the surface of the housing at the position where the housing is attached to the mounting portion, the recess being recessed toward the mounting portion.

[0012] In this battery, a recess is formed on the surface of the housing at the location where the housing is attached to the attachment part, which recess is recessed toward the attachment part. That is, in this battery, the surface of the housing at the location where the housing is attached to the attachment part is pressed, and the housing and the electrode tab are more firmly joined. Therefore, with this battery, the airtightness of the battery can be further improved.

[0013] In the battery, an adhesive layer may be formed between the mounting portion and the container.

[0014] In the battery, the adhesive layer may be a film-like adhesive member.

[0015] A method for attaching an electrode tab according to another aspect of the present invention includes the steps of sandwiching an attachment portion of the electrode tab with a housing, and heat-sealing an area of ​​the housing that sandwiches the electrode tab.

[0016] In the electrode tab attached to the housing in this attachment method, a curve connecting a point on the outer periphery corresponding to the central portion and a point on the outer periphery corresponding to the end portion has at least one inflection point in a cross section of the attachment portion. Therefore, according to this electrode tab attachment method, the thickness of the electrode tab does not rapidly decrease at the ends in the width direction, so that the electrode tab can be sufficiently adhered to the housing and airtightness of the battery can be sufficiently ensured.

[0017] The above-mentioned method for attaching an electrode tab may further include a step of forming a recess recessed toward the attachment portion on the surface of the housing at the position where the housing is attached to the attachment portion.

[0018] That is, in this electrode tab attachment method, the surface of the housing at the location attached to the attachment part is pressed, and the housing and the electrode tab are more firmly joined together. Therefore, this electrode tab attachment method can further improve the airtightness of the battery. Effect of the Invention

[0019] According to the present invention, it is possible to provide an electrode tab that can sufficiently ensure airtightness of a battery even if the thickness of the electrode tab is increased to a certain extent. [Brief description of the drawings]

[0020] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III of FIG. [Figure 4] FIG. 13 is a plan view of the electrode tab when attached to the housing. [Diagram 5] FIG. 5 is a cross-sectional view of FIG. 4 . [Figure 6] 10 is a flowchart showing a manufacturing procedure of the electrode tab. [Figure 7] 10 is a flowchart showing a procedure for attaching the electrode tab to the container. [Figure 8] 13 is a diagram showing a cross-sectional shape of an attachment portion of an electrode tab in Modification 1. FIG. [Figure 9] 13 is a diagram showing a cross-sectional shape of an attachment portion of an electrode tab in Modification 2. FIG. [Figure 10] 13 is a diagram showing a cross-sectional shape of an attachment portion of an electrode tab in Modification 3. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0022] [1. Overview] Fig. 1 is a plan view of a battery 10 including an electrode tab 100 according to the present embodiment. As shown in Fig. 1, the battery 10 includes a battery element 300, a pouch-shaped container 200, and electrode tabs 100 (100A, 100B).

[0023] The battery element 300 is an electricity storage member such as a lithium ion battery, a capacitor, or an all-solid-state battery.

[0024] The pouch-shaped housing 200 is made of, for example, a laminate (laminate film) having a base layer, a barrier layer, and a heat-sealable resin layer in this order. For example, the housing 200 is made of two laminate films, and the edges (sealed portion 210) of the overlapped laminate films are heat-sealed. The housing 200 is configured to house the battery element 300 therein with the electrode tabs 100A and 100B sandwiched at the edges.

[0025] The electrode tabs 100 (100A, 100B) are metal terminals used for inputting and outputting power in the battery element 300. One end of each electrode tab 100 is electrically connected to an electrode (positive electrode or negative electrode) of the battery element 300, and the other end protrudes outward from the edge of the housing 200.

[0026] The metal material constituting the electrode tab 100 is, for example, aluminum, nickel, copper, etc. For example, when the battery element 300 is a lithium ion battery, the electrode tab 100 connected to the positive electrode is usually made of aluminum, etc., and the electrode tab 100 connected to the negative electrode is usually made of copper, nickel, etc. Furthermore, the surface of the electrode tab 100 made of these metal materials can be subjected to a surface treatment such as providing an easy-adhesion layer. This is for the purpose of firmly attaching the adhesive film 120 (FIGS. 2 and 3) described later to the surface of the electrode tab main body 110, and this is made possible by making the easy-adhesion layer of the same type of resin as the outermost layer of the adhesive film 120. In addition, it is also possible to perform a surface treatment to roughen the surface of the electrode tab main body 110 in order to firmly attach the adhesive film 120 to the surface of the electrode tab main body 110.

[0027] Generally, as the maximum input / output power of a secondary battery increases, the thickness of the electrode tab used in the secondary battery increases. If the electrode tab is thick, when the housing is heat-sealed with the electrode tab sandwiched between them, the gap between the electrode tab and the housing is not sufficiently filled with resin, and a gap is likely to occur. In other words, if the electrode tab is thick, it is difficult to ensure sufficient airtightness of the secondary battery.

[0028] In the electrode tab 100 according to the present embodiment, the cross-sectional shape of the electrode tab 100 is devised to ensure sufficient airtightness of the battery 10 even if the thickness of the electrode tab 100 is increased. Below, the configuration of the electrode tab 100, the state in which the electrode tab 100 is attached to the housing 200, the manufacturing method of the electrode tab 100, and the method of attaching the electrode tab 100 to the housing 200 will be described in order.

[0029] [2. Electrode tab configuration] 2 is a plan view of the electrode tab 100. As shown in FIG. 2, the electrode tab 100 includes an electrode tab main body 110 and an adhesive film 120. That is, in the electrode tab 100, the adhesive film 120 is attached to the electrode tab main body 110 in advance. The electrode tab main body 110 includes an attachment portion 112, a wiring connection portion 114, and an electrode connection portion 116. The attachment portion 112 is an area where the adhesive film 120 is attached. The wiring connection portion 114 is an area for connecting wiring connected to a load. The electrode connection portion 116 is an area for connecting the electrodes of the battery element 300.

[0030] The adhesive film 120 is configured to be adhered to both the electrode tab body 110 and the housing 200 (FIG. 1) by heat sealing. Various known adhesive films can be adopted as the adhesive film 120. As an example, the adhesive film 120 may be a single-layer film of maleic anhydride modified polypropylene (PPa), or a laminated film of PPa, polyethylene naphthalate (PEN) and PPa. Moreover, instead of the above PPa resin, resins capable of adhering to metals, such as ionomer resins, modified polyethylene, EVA, etc., can also be applied.

[0031] In this embodiment, a three-layer laminate film including a core material, consisting of PPa / PEN (core material) / PPa, is used as the adhesive film 120. As the core material, various known materials can be used in addition to the above-mentioned PEN. As an example, the core material may be polyester fiber, polyamide fiber, or carbon fiber. The reason why the adhesive film 120 includes a core material will be explained in detail later.

[0032] As described above, the adhesive film 120 is adhered to the electrode tab body 110 in a state in which it covers the outer periphery of the attachment portion 112 of the electrode tab body 110. Since the adhesive film 120 is also adhered to the housing 200 (FIG. 1), according to the electrode tab 100, the metal electrode tab 100 and the housing 200 can be easily adhered to each other by heat sealing.

[0033] Furthermore, the widthwise length W1 of the adhesive film 120 is longer than the widthwise length W2 of the attachment portion 112. That is, in the electrode tab 100, the adhesive film 120 extends over at least one circumference of the attachment portion 112. Therefore, according to the electrode tab 100, the adhesive film 120 has a wide arrangement range, and therefore the adhesion between the electrode tab 100 and the housing 200 can be more reliably achieved.

[0034] Fig. 3 is a cross-sectional view taken along line III-III of Fig. 2. As shown in Fig. 3, the cross section of the mounting portion 112 of the electrode tab 100 has a shape that is curved all around. The cross section of the mounting portion 112 includes the circular portion 102 and the wing-like extension ends 104 and 106.

[0035] In a cross section of the attachment portion 112, the thickness of the widthwise center portion (thickness of the circular portion 102) is greater than the thickness of the widthwise end portions (thickness at the tips of the wing-like extension portions 104, 106).

[0036] In addition, in the cross section of the attachment portion 112, a curve connecting point P1 on the outer circumference corresponding to the widthwise center and point P3 on the outer circumference corresponding to the widthwise end has inflection points P5 and P6. A curve connecting point P1 on the outer circumference corresponding to the widthwise center and point P4 on the outer circumference corresponding to the widthwise end has inflection points P7 and P8. A curve connecting point P2 on the outer circumference corresponding to the widthwise center and point P3 on the outer circumference corresponding to the widthwise end has inflection points P9 and P10. A curve connecting point P2 on the outer circumference corresponding to the widthwise center and point P4 on the outer circumference corresponding to the widthwise end has inflection points P11 and P12. In addition, the "center" in the width direction in the cross section of mounting portion 112 refers to the center in the width direction in the cross section of mounting portion 112 (for example, the area between points P1 and P2), and the "end" in the width direction in the cross section of mounting portion 112 refers to the ends in the width direction in the cross section of mounting portion 112 (for example, points P3 and P4).

[0037] If the thickness of the electrode tab is abruptly thinned at the end in the width direction (if a large step is formed), sufficient adhesion may not be achieved at that position, and the airtightness of the secondary battery may decrease. In the cross section of the electrode tab 100, a curve connecting at least a portion between any point on the outer periphery corresponding to the center in the width direction (points P1, P2) and any point on the outer periphery corresponding to the end in the width direction (points P3, P4) has at least one inflection point (inflection points P5, P6, P7, P8, P9, P10, P11, P12).

[0038] That is, in the cross section of the attachment portion 112 of the electrode tab 100, the cross-sectional thickness is large and smoothly decreases in the region near the center, and the cross-sectional thickness is small and smoothly decreases in the region near the end. In addition, the region near the center and the region near the end are smoothly connected. Therefore, according to the electrode tab 100, the thickness does not rapidly decrease at the end of the electrode tab 100 in the width direction, and each region is smoothly connected, so that even if the thickness of the electrode tab 100 becomes thick to a certain extent, the electrode tab 100 can be sufficiently adhered to the housing 200, and the airtightness of the battery 10 can be sufficiently ensured.

[0039] The cross-sectional shape of the wiring connection portion 114 and the electrode connection portion 116 may be the same as the cross-sectional shape of the attachment portion 112, or may be different.

[0040] [3. Electrode tab installation status] Fig. 4 is a plan view of the electrode tab 100 attached to the housing 200. Fig. 5 is a VV cross-sectional view of Fig. 4. As shown in Fig. 4 and Fig. 5, in the housing 200, the sealed portion 210 is heat-sealed with the electrode tab 100 sandwiched between them. The details will be described later, but the sealed portion 210 is adhered by a first heat seal.

[0041] Furthermore, a recess 212 recessed toward the mounting portion 112 is formed on the surface of the seal portion 210 at a position corresponding to above the mounting portion 112 of the electrode tab 100. The recess 212 is formed by the second heat sealing. That is, in the battery 10, the surface of the container 200 at the position attached to the mounting portion 112 is pressed, and the container 200 and the electrode tab 100 are more firmly joined. Therefore, according to this battery 10, the airtightness of the battery 10 can be further improved.

[0042] As described above, the adhesive film 120 in the electrode tab 100 includes a core material. If the adhesive film 120 does not include a core material, when heat sealing is repeatedly performed (for example, twice), the heat and pressure may cause the heat-sealing resin layer and adhesive film constituting the inner layer of the housing 200 to melt and be pushed out to the part where the pressure is weak. As a result, the metal foil layer such as aluminum foil constituting the barrier layer of the housing 200 and the electrode tab main body 110 are short-circuited, and the insulating layer (the heat-sealing resin layer and adhesive film constituting the inner layer of the housing) is destroyed at the location where the electrode tab 100 is sandwiched in the housing 200, and a short circuit may occur in the housing 200. In the electrode tab 100 according to this embodiment, the adhesive film 120 includes a core material. Therefore, according to this electrode tab 100, the adhesive film 120 containing the core material suppresses destruction of the insulating layer, so that the insulation within the housing 200 can be maintained even if heat sealing is performed twice (multiple times) near the electrode tab 100.

[0043] [4. Manufacturing method of electrode tab] 6 is a flowchart showing a manufacturing procedure of the electrode tab 100. The process shown in this flowchart is executed by, for example, a manufacturing device in a state in which the electrode tab body 110 and the adhesive film 120 are prepared.

[0044] 6, the manufacturing device sandwiches the attachment portion 112 of the electrode tab main body 110 between the adhesive films 120 (step S100). With the attachment portion 112 sandwiched between the adhesive films 120, the manufacturing device heat-seals the adhesive film 120 to the attachment portion 112 (step S110). This completes the electrode tab 100. The effect of previously attaching the adhesive film 120 to the electrode tab main body 110 by heat sealing is as follows. When the electrode tab main body 110 is made of thick metal, even if only one place, specifically, only the attachment portion 112 which is a part of the electrode tab main body 110, is heat-sealed and heated, heat is transferred to the entire area other than the attachment portion 112 and dissipated from the metal surface that is not in contact with the seal bar. Therefore, rather than heat-sealing the electrode tab main body 110 and the adhesive film 120 at the same time as heat-sealing the housing 200, it is possible to more stably adhere the adhesive film 120 to the electrode tab main body 110 by heat-sealing the adhesive film 120 to the electrode tab main body 110 in advance.

[0045] [5. How to attach the electrode tab] 7 is a flowchart showing a procedure for attaching the electrode tab 100 to the housing 200. The process shown in this flowchart is executed, for example, by a manufacturing device in a state in which the electrode tab 100 and the housing 200 are prepared.

[0046] 7, the manufacturing apparatus places the electrode tab 100 on the housing 200 (step S200). For example, the manufacturing apparatus places the electrode tab 100 on the housing 200 so that the electrode tab 100 is sandwiched between the peripheral edge of the housing 200. In this state, one end of the electrode tab 100 is connected to an electrode of the battery element 300.

[0047] The manufacturing equipment performs a first heat seal (primary heat seal) with the electrode tab 100 sandwiched between the periphery of the housing 200 (step S210). As a result, the entire periphery of the housing 200 is heat sealed. Thereafter, the manufacturing equipment performs a second heat seal (secondary heat seal) to further strengthen the seal around the electrode tab 100 (step S220). As a result, the periphery of the electrode tab 100 (recess 212) is further strongly heat sealed. As a result, the electrode tab 100 is attached to the housing 200.

[0048] [6. Features] As described above, in the electrode tab 100 according to the present embodiment, in the cross section of the mounting portion 112, a curve connecting at least a portion between any point on the outer periphery corresponding to the widthwise center (points P1, P2) and any point on the outer periphery corresponding to the widthwise end (points P3, P4) has at least one inflection point (inflection points P5, P6, P7, P8, P9, P10, P11, P12).

[0049] That is, in the cross section of the attachment portion 112 of the electrode tab 100, the cross-sectional thickness is large and smoothly decreases in the region near the center, and the cross-sectional thickness is small and smoothly decreases in the region near the end. In addition, the region near the center and the region near the end are smoothly connected. Therefore, according to the electrode tab 100, the thickness does not rapidly decrease at the end of the electrode tab 100 in the width direction, and each region is smoothly connected, so that even if the thickness of the electrode tab 100 becomes thick to a certain extent, the electrode tab 100 can be sufficiently adhered to the housing 200, and the airtightness of the battery 10 can be sufficiently ensured.

[0050] [7. Modifications] Although the embodiment has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0051] <7-1> In the above embodiment, the cross-sectional shape of the mounting portion 112 is the shape shown in Fig. 3. However, the cross-sectional shape of the mounting portion 112 is not limited to the shape shown in Fig. 3. For example, the cross-sectional shape of the mounting portion 112 may be a shape such as the following modified example 1-3.

[0052] Fig. 8 is a diagram showing the cross-sectional shape of attachment portion 112A of electrode tab 100A in Modification 1. As shown in Fig. 8, the cross-sectional shape of the attachment portion may have only one inflection point P7A in a curve connecting point P1A on the outer periphery corresponding to the center in the width direction and point P4A on the outer periphery corresponding to the end in the width direction.

[0053] Moreover, Fig. 9 is a diagram showing a cross-sectional shape of attachment portion 112B of electrode tab 100B in Modification 2. As shown in Fig. 9, the cross-sectional shape of the attachment portion may include flat portions 117, 118, for example, between a point on the outer periphery corresponding to the center in the width direction and a point on the outer periphery corresponding to an end in the width direction.

[0054] 10 is a diagram showing a cross-sectional shape of an attachment portion 112C of an electrode tab 100C in Modification Example 3. As shown in Fig. 10, the cross-sectional shape of the attachment portion may be such that, for example, a curve connecting a point on the outer periphery corresponding to the center in the width direction and a point on the outer periphery corresponding to an end in the width direction has only one inflection point, and a flat portion is included between the point on the outer periphery corresponding to the center in the width direction and the point on the outer periphery corresponding to the end in the width direction.

[0055] <7-2> Furthermore, in the electrode tab 100 according to the above embodiment, the adhesive film 120 is pre-adhered to the electrode tab main body 110. However, the adhesive film 120 does not necessarily have to be pre-adhered to the electrode tab main body 110. For example, the adhesive film 120 may be sandwiched between the electrode tab 100 and the housing 200 for the first time when the electrode tab 100 and the housing 200 are heat-sealed.

[0056] <7-3> Furthermore, in the electrode tab 100 according to the above embodiment, the adhesive film 120 is adhered to the electrode tab main body 110. However, the adhesive member adhered to the electrode tab main body 110 is not limited to the adhesive film 120. For example, an adhesive resin layer may simply be formed on the surface of the attachment portion 112 of the electrode tab main body 110.

[0057] <7-4> In the above embodiment, heat sealing is performed twice to attach the electrode tab 100 to the housing 200. However, heat sealing does not necessarily have to be performed twice. For example, heat sealing may be performed only once to bond the seal portion 210.

[0058] <7-5> In addition, in the cross section of the attachment portion 112 of the electrode tab 100 according to the above embodiment, the curve connecting any point on the outer circumference corresponding to the center in the width direction and any point on the outer circumference corresponding to the end in the width direction has two inflection points. However, the number of inflection points included in the curve is not limited to two. The number of inflection points included in the curve may be one as described above, or may be three or more.

[0059] <7-6> In the above embodiment, the adhesive film 120 includes a core material. However, the adhesive film 120 does not necessarily need to include a core material.

[0060] <7-7> In the above embodiment, the electrode tabs 100A, 100B are arranged on opposing sides of the battery 10. However, the locations of the electrode tabs 100A, 100B are not limited to this. For example, the electrode tabs 100A, 100B may be arranged on the same side of the battery 10. [Explanation of symbols]

[0061] 10 battery, 100, 100A, 100B, 100C electrode tab, 102 circular portion, 104, 106 wing-shaped extension end, 110 electrode tab body, 112, 112A, 112B mounting portion, 114 wiring connection portion, 116 electrode connection portion, 117, 118 flat portion, 120 adhesive film, 200 container, 210 sealing portion, 212 recess, 300 battery element.

Claims

1. An electrode tab that can be attached to a pouch-shaped container that contains a battery element and is configured to be electrically connected to an electrode of the battery element, a mounting portion configured to be attached to the housing; In a cross section of the mounting portion in the width direction, a thickness of a central portion in the width direction is greater than a thickness of an end portion in the width direction, In the cross section, a curve connecting at least a part between any point on the outer periphery corresponding to the central portion and any point on the outer periphery corresponding to the end portion has at least one inflection point; The central portion has a curved shape, The mounting portion includes a circular portion including the central portion. Electrode tab.

2. The mounting portion is In the width direction, a wing-shaped extension end portion extends in the width direction from an end portion of the circular portion, In the width direction, the width of the circular portion is longer than the wing-like extension tip. The electrode tab of claim 1 .

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