Current collector foil for liquid battery and liquid battery

Abstract

To provide a current collector foil for a liquid battery which can reduce the number of pinholes extending from a first-1 electrode foil to a second electrode foil.SOLUTION: The current collector foil for a liquid battery includes: a first-1 electrode foil with a pinhole; a first intervening layer; a first-2 electrode foil with a pinhole; a second intervening layer; and a second electrode foil in that order. One of the pair of the first-1 electrode foil and the first-2 electrode foil, and the second electrode foil, is a positive electrode foil, and the other is a negative electrode foil.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a current collector foil for a liquid battery, and to a liquid battery. [Background technology]

[0002] Conventionally, a current collector foil for a liquid battery has been used in which a positive electrode foil and a negative electrode foil are bonded together.

[0003] For example, Patent Document 1 discloses a bipolar current collector having a positive electrode current collector with an aluminum layer, a negative electrode current collector with a copper layer, and an intermediate layer interposed between the aluminum layer and the copper layer, the copper layer having a thickness of 3 to 10 μm, and the intermediate layer having a porous anodized aluminum portion and a nickel portion present in the pores of the anodized aluminum portion.

[0004] Patent Document 2 discloses a bipolar battery comprising a first member, a second member, and a laminated electrode body arranged between them, the laminated electrode body comprising a first current collector constituting one end face in the stacking direction, a second current collector constituting the other end face in the stacking direction, at least one bipolar current collector arranged between the first current collector and the second current collector, and a plurality of power generating elements electrically connected in series between the first current collector and the second current collector via the bipolar current collector, the first current collector being arranged between the first member and the bipolar current collector, the second current collector being arranged between the second member and the bipolar current collector, the first current collector having a first tab, and the second current collector having a second tab, the amount of heat generated by the first tab being greater than the amount of heat generated by the second tab when the battery is energized, the first member being a cooling member that cools the first current collector, and the cooling performance of the first member being greater than the cooling performance of the second member. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2023-053669 A [Patent Document 2] JP 2021-136115 A Summary of the Invention [Problem to be solved by the invention]

[0006] Conventionally, current collector foils in which a positive electrode foil and a negative electrode foil are bonded together with an intervening agent have been used as current collector foils for liquid batteries. However, metal foils used for the positive electrode foil and the negative electrode foil may have pinholes during the manufacturing process. When a current collector foil having a pinhole in at least one of the positive electrode foil and the negative electrode foil is used in a liquid battery, a through hole penetrating the positive electrode foil, the intervening layer, and the negative electrode foil may be formed, and a liquid junction may occur through the through hole in the liquid battery.

[0007] The present disclosure has been made in consideration of the above circumstances, and aims to provide a current collecting foil for a liquid battery that can reduce the number of pinholes reaching from the 1-1 electrode foil to the 2nd electrode foil, and a liquid battery that can suppress the occurrence of liquid junctions. [Means for solving the problem]

[0008] Means for solving the above problems include the following aspects. <1> A 1-1 electrode foil having a pinhole; A first intermediate layer; A first-second electrode foil having a pinhole; A second intermediate layer; a second electrode foil, and One of the 1-1 electrode foil and the 1-2 electrode foil, and the second electrode foil, is a positive electrode foil, and the other is a negative electrode foil. <2> <1> 13. A liquid battery comprising the liquid battery current collector foil according to claim 12, a positive electrode active material layer, a negative electrode active material layer, a separator, and an electrolyte. Effect of the Invention

[0009] According to the present disclosure, there is provided a current collecting foil for a liquid battery that can reduce the number of pinholes reaching from the 1-1 electrode foil to the 2nd electrode foil, and a liquid battery that can suppress the occurrence of liquid junctions. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a schematic cross-sectional view showing the configuration of a current collector foil according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is a schematic cross-sectional view showing the configuration of a conventional current collector foil. [Diagram 3] FIG. 2 is a schematic cross-sectional view showing a current collector foil manufacturing apparatus used to manufacture a current collector foil according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] An embodiment that is an example of the present disclosure will now be described. These descriptions and examples are merely illustrative of the embodiments and are not intended to limit the scope of the invention. In this specification, a numerical range expressed using "to" means a range that includes these numerical values ​​as the lower limit and upper limit. In the present specification, the upper limit of a certain numerical range may be replaced by the upper limit of another numerical range, or may be replaced by a value shown in an example. The lower limit of a certain numerical range may be replaced by the lower limit of another numerical range, or may be replaced by a value shown in an example. Furthermore, "%" for the content means "% by mass" unless otherwise specified.

[0012] Each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of those multiple substances present in the composition. The term "process" includes not only independent processes, but also processes that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved.

[0013] <Current collecting foil for liquid batteries> A current collector foil for a liquid battery according to an embodiment of the present disclosure (hereinafter also simply referred to as a "current collector foil") is formed by laminating, in this order, a 1-1 electrode foil having a pinhole, a first intermediate layer, a 1-2 electrode foil having a pinhole, a second intermediate layer, and a second electrode foil. One of the 1-1 and 1-2 electrode foils and the second electrode foil is a positive electrode foil, and the other is a negative electrode foil. In other words, when the 1-1 and 1-2 electrode foils are positive electrode foils, the second electrode foil is a negative electrode foil, and when the 1-1 and 1-2 electrode foils are negative electrode foils, the second electrode foil is a positive electrode foil.

[0014] That is, in the current collector foil according to the embodiment of the present disclosure, two or more layers of positive electrode foil having a pinhole are laminated, and a negative electrode layer is further laminated on one surface of the laminated foil, or two or more layers of negative electrode foil having a pinhole are laminated, and a positive electrode layer is further laminated on one surface of the laminated foil.

[0015] The current collecting foil according to the embodiment of the present disclosure has the above-mentioned configuration, and thus can reduce the number of pinholes extending from the 1-1 electrode foil to the 2nd electrode foil. As a result, when this current collecting foil is used in a liquid battery, the occurrence of through holes in the current collecting foil can be suppressed, and the occurrence of liquid junctions in the liquid battery can be suppressed.

[0016] Conventionally, current collector foils have been used in which a positive electrode foil and a negative electrode foil are bonded together via an intervening layer (e.g., an adhesive layer). However, the metal foils used for the positive electrode foil and the negative electrode foil can have pinholes (small holes penetrating the metal foil) during the manufacturing process.

[0017] 2, when a current collector foil 110 obtained by bonding a positive electrode foil 112 having a pinhole 1120 to a negative electrode foil 114 via an intermediate layer 140 is used in a liquid battery, a through hole penetrating all of the positive electrode foil 112, the intermediate layer 140, and the negative electrode foil 114 may be formed at the location of the pinhole 1120 in the positive electrode foil 112. Specifically, at the location of the pinhole 1120 in the positive electrode foil 112, a hole may also be formed in the intermediate layer 140 formed on the pinhole 1120, that is, the pinhole 1120 may not be blocked by the intermediate layer 140. When the current collector foil 110 obtained by laminating the negative foil 114 to the positive foil 112 and the intermediate layer 140 is used in a liquid battery, the electrolyte penetrates into the holes penetrating the positive foil 112 and the intermediate layer 140, and the electrolyte comes into contact with the negative foil 114. When the battery is repeatedly charged and discharged in this state, a reaction with the electrolyte (for example, when a copper foil is used as the negative foil 114, Cu → Cu 2+ +2e - The reaction (reaction (a) of the positive electrode foil 112 with the negative electrode foil 114) may also cause holes in the negative electrode foil 114. As a result, holes are formed that extend completely through the positive electrode foil 112, the intermediate layer 140, and the negative electrode foil 114. In addition, when a current collector foil obtained by laminating a negative foil having a pinhole and a positive foil with an intervening layer is used in a liquid battery, a through hole may be formed at the pinhole in the positive foil, penetrating the positive foil, the intervening layer, and the negative foil. Specifically, at the pinhole in the negative foil, a hole may also be formed in the intervening layer formed on the pinhole, that is, the pinhole may not be blocked by the intervening layer. When a current collector foil obtained by laminating a positive foil to the negative foil and the intervening layer is used in a liquid battery, the electrolyte penetrates into the hole penetrating the negative foil and the intervening layer, and the electrolyte comes into contact with the positive foil. When the battery is repeatedly charged and discharged in this state, the positive foil may crack, and as a result, a through hole is formed that completely penetrates the negative foil, the intervening layer, and the positive foil.

[0018] In a current collector foil having a through hole formed therein that penetrates the positive electrode foil, the intervening layer, and the negative electrode foil, one side of the current collector foil communicates with the other side through the through hole, resulting in a liquid junction.

[0019] Therefore, in the current collector foil according to the embodiment of the present disclosure, a 1-1 electrode foil having a pinhole, a first intermediate layer, a 1-2 electrode foil having a pinhole, a second intermediate layer, and a second electrode foil are laminated in this order. For example, as shown in FIG. 1, a current collector foil 10A may be formed by stacking a positive electrode foil 12A having a pinhole 120A, a first intermediate layer 40A, a positive electrode foil 12B having a pinhole 120B, a second intermediate layer 40B, and a negative electrode foil 14A in this order. Both the positive electrode foil 12A and the positive electrode foil 12B have pinholes 120A and 120B, but the possibility that the position of the pinhole 120A in the positive electrode foil 12A and the position of the pinhole 120B in the positive electrode foil 12B overlap is extremely small. In other words, by stacking the positive electrode foil 12A having the pinhole 120A and the positive electrode foil 12B having the pinhole 120B, it is possible to reduce pinholes reaching from the positive electrode foil 12A to the negative electrode foil 14A.

[0020] Thus, with the current collecting foil according to the embodiment of the present disclosure, it is possible to reduce the number of pinholes extending from the 1-1 electrode foil to the 2nd electrode foil, and as a result, when this current collecting foil is used in a liquid battery, it is possible to suppress the occurrence of through holes in the current collecting foil, and thus the occurrence of liquid short circuits in the liquid battery.

[0021] No. 1-1 electrode foil and No. 1-2 electrode foil In the current collector foil according to the embodiment of the present disclosure, one of the 1-1 electrode foil and the 1-2 electrode foil having pinholes and the second electrode foil is a positive electrode foil, and the other is a negative electrode foil. In other words, the 1-1 electrode foil and the 1-2 electrode foil having pinholes may be either a positive electrode foil or a negative electrode foil. However, it is the positive electrode foil (particularly an Al foil) that is most likely to have pinholes, and from the viewpoint of reducing the number of pinholes that are caused by pinholes in the positive electrode and reach from the 1-1 electrode foil to the second electrode foil, it is preferable that the 1-1 electrode foil and the 1-2 electrode foil are positive electrode foils.

[0022] The 1-1 electrode foil and the 1-2 electrode foil are not particularly limited in material, so long as they are both positive electrode foils or negative electrode foils. Therefore, the 1-1 electrode foil and the 1-2 electrode foil may be positive electrode foils made of different materials, or may be negative electrode foils made of different materials. However, it is more preferable that the 1-1 electrode foil and the 1-2 electrode foil are foils made of the same material.

[0023] The current collector foil according to the embodiment of the present disclosure may further include, in addition to the 1-1 electrode foil and the 1-2 electrode foil, a foil having a pinhole and having the same curve as the 1-1 electrode foil and the 1-2 electrode foil. That is, when the 1-1 electrode foil and the 1-2 electrode foil are positive electrode foils, three or more layers of positive electrode foils having pinholes may be laminated. Similarly, when the 1-1 electrode foil and the 1-2 electrode foil are negative electrode foils, three or more layers of negative electrode foils having pinholes may be laminated. In addition, the second electrode foil may further include a foil having the same curve as the second electrode foil; that is, when the second electrode foil is a negative electrode foil, two or more layers of negative electrode foils may be laminated, and when the second electrode foil is a positive electrode foil, two or more layers of positive electrode foils may be laminated.

[0024] Positive electrode foil The positive electrode foil used in the embodiment of the present disclosure is preferably a conductive member made of a metal with good conductivity (e.g., aluminum). The thickness of the positive electrode foil is preferably, for example, 10 μm or more and 100 μm or less, and more preferably 20 μm or more and 60 μm or less.

[0025] Negative electrode foil On the other hand, the negative electrode foil is preferably a conductive member made of a metal with good conductivity (for example, copper). The thickness of the negative electrode foil is preferably, for example, 1 μm or more and 20 μm or less, and more preferably 3 μm or more and 12 μm or less.

[0026] ·First intervening layer and second intervening layer The first and second intermediate layers (hereinafter, both of which are also simply referred to as "intermediate layers") of the current collector foil according to the embodiment of the present disclosure are not particularly limited as long as they are layers that have the function of adhering the 1-1 electrode foil and the 1-2 electrode foil, and the 1-2 electrode foil and the 2nd electrode foil. An example of the intermediate layer is an adhesive layer (adhesive layer). The adhesive constituting the adhesive is preferably an adhesive in which a curing agent (e.g., an isocyanate-based curing agent) is added to a base material (e.g., an olefin-based resin). A conductive assistant (e.g., particles with Ni plating on the surface) may also be added to the adhesive. The thickness of the intermediate layer is not particularly limited, but is preferably, for example, from 0.5 μm to 15 μm, and more preferably from 1.0 μm to 10 μm.

[0027] (Manufacturing method) Next, an example of a method for producing a current collector foil according to an embodiment of the present disclosure will be described with reference to the drawings.

[0028] Fig. 3 is a schematic diagram showing a current collector foil manufacturing apparatus for manufacturing a current collector foil according to an embodiment of the present disclosure. The current collector foil according to an embodiment of the present disclosure can be manufactured, for example, by laminating a 1-1 electrode foil having a pinhole and a 1-2 electrode foil having a pinhole with a first intermediate layer therebetween using the current collector foil manufacturing apparatus shown in Fig. 3, and then further laminating a second electrode foil on the 1-2 electrode foil side with a second intermediate layer therebetween using the current collector foil manufacturing apparatus shown in Fig. 3.

[0029] Hereinafter, a method for manufacturing a current collector foil according to an embodiment of the present disclosure using the current collector foil manufacturing apparatus shown in Fig. 3 will be specifically described. Note that in the following, an example will be described in which the 1-1 electrode foil having a pinhole is a first aluminum foil (first Al foil) serving as a positive electrode foil, the 1-2 electrode foil having a pinhole is a second aluminum foil (second Al foil) serving as a positive electrode foil, the second electrode foil is a copper foil (Cu foil) serving as a negative electrode foil, and the first and second intermediate layers are a first adhesive layer and a second adhesive layer, respectively.

[0030] (A1) First coating process First, in the current collector foil manufacturing apparatus 100 shown in FIG. 3, a first Al foil is used for the base foil 12, a second Al foil is used for the laminating foil 14, and an adhesive for forming a first adhesive layer is used for the adhesive 40. The first Al foil, which is the base foil 12, is transported to a roll pair consisting of a coating roll 22A (e.g., a gravure roll) and an opposing roll 22B. The coating roll 22A is partially immersed in an adhesive 40, and the adhesive 40 (adhesive for forming a first adhesive layer) attached to the surface of the coating roll 22A is applied (e.g., gravure coated) from the coating roll 22A to one side of the base foil 12 (first Al foil).

[0031] (A2) First drying process Next, the base foil 12 (first Al foil) that has passed the contact position with the coating roll 22A is transported via the transport roll 24 to the drying furnace 30. In the transport path 30, the adhesive 40 on the base foil 12 (first Al foil) is heated in the drying furnace 30 and dried.

[0032] (A3) First heat welding process Next, the base foil 12 (first Al foil) that has passed through the drying furnace 30 is transported to a contact position with the pair of heated rolls 28A and 28B via the transport roll 26. At the nip between the pair of heated rolls 28A and 28B, the lamination foil 14 (second Al foil) transported from another direction is laminated to the surface of the base foil 12 (first Al foil) on which the adhesive 40 is applied, and is heated and pressed by the pair of heated rolls 28A and 28B, so that the base foil 12 (first Al foil) and the lamination foil 14 (second Al foil) are thermally welded together via the adhesive 40 (first adhesive layer). In this way, a foil in which the first Al foil and the second Al foil are thermally welded together (hereinafter referred to as a "double Al foil") is obtained as the wound foil 10.

[0033] Next, the current collector foil manufacturing apparatus shown in FIG. 3 is used again to laminate the Cu foil.

[0034] (B1) Second coating process Specifically, in the current collector foil manufacturing apparatus 100 shown in FIG. 3, the double Al foil obtained above is used for the base foil 12, a Cu foil is used for the laminating foil 14, and an adhesive for forming a second adhesive layer is used for the adhesive 40. The double-layered Al foil, which is the base foil 12, is transported to a roll pair consisting of a coating roll 22A (e.g., a gravure roll) and an opposing roll 22B. The adhesive 40 (adhesive for forming a second adhesive layer) attached to the surface of the coating roll 22A is applied (e.g., gravure coated) from the coating roll 22A to one side of the base foil 12 (double-layered Al foil).

[0035] (B2) Second drying process Next, the base foil 12 (double-layered Al foil) that has passed the contact position with the coating roll 22A is transported via the transport roll 24 to the drying furnace 30. In the transport path 30, the adhesive 40 on the base foil 12 (double-layered Al foil) is heated in the drying furnace 30 and dried.

[0036] (B3) Second heat welding process Next, the base foil 12 (double Al foil) that has passed through the drying furnace 30 is transported to a contact position with the pair of heated rolls 28A and 28B via the transport roll 26. In the nip between the pair of heated rolls 28A and 28B, the lamination foil 14 (Cu foil) transported from another direction is laminated to the surface of the base foil 12 (double Al foil) on which the adhesive 40 has been applied, and is heated and pressed by the pair of heated rolls 28A and 28B, whereby the base foil 12 (double Al foil) and the lamination foil 14 (Cu foil) are thermally welded together via the adhesive 40 (second adhesive layer). Through these steps, a current collector foil is produced as the winding foil 10 in which the first Al foil, the second Al foil, and the Cu foil are bonded together via the first adhesive layer and the second adhesive layer, respectively.

[0037] The heating temperature in the first and second drying steps (the temperature inside the drying furnace 30 in FIG. 3) can be adjusted depending on the material of the intervening layer used, and is preferably, for example, from 80° C. to 200° C., and more preferably from 100° C. to 180° C.

[0038] In addition, the heating temperatures in the first and second thermal welding steps (the temperatures of the thermal roll pairs 28A and 28B in FIG. 3) can be adjusted according to the material of the intervening layer used. For example, it is preferably 50°C or higher and 150°C or lower, and more preferably 70°C or higher and 120°C or lower. In addition, the pressure applied in the first and second thermal welding steps (the nip pressure by the thermal roll pairs 28A and 28B in FIG. 3) is preferably, for example, 0.20 MPa or higher and 0.70 MPa or lower, and more preferably 0.30 MPa or higher and 0.60 MPa or lower.

[0039] <Liquid-based battery> The liquid-based battery according to the embodiment of the present disclosure includes the current collector foil for the liquid-based battery according to the embodiment of the present disclosure described above, a positive electrode active material layer, a negative electrode active layer, a separator, and an electrolytic solution.

[0040] (Positive electrode active material layer) The positive electrode composite layer contains a positive electrode active material and may further contain, for example, a binder. Examples of the positive electrode active material include lithium nickel cobalt manganese composite oxide (hereinafter sometimes simply referred to as "LNCM"). The simplest LNCM has the following general formula: LiNi x Co y Mn z O2 (where x, y, and z in the formula satisfy 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1). LNCM may contain, in addition to Li, Ni, Co, and Mn, other additive elements, for example, transition metal elements other than Ni, Co, and Mn, and typical metal elements other than Li. LNCM has a layered crystal structure. LNCM exceeds 50% by mass of the entire positive electrode active material and preferably occupies, for example, 80 to 100% by mass. The positive electrode active material may be composed of only LNCM. Examples of other positive electrode active materials include lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel manganese composite oxide, and the like.

[0041] An example of the binder contained in the positive electrode mixture layer is a vinyl halide resin such as polyvinylidene fluoride (PVdF). The positive electrode mixture layer may further contain other components, such as a conductive material, etc. Examples of the conductive material include non-graphitizable carbon, easily graphitizable carbon such as carbon black, and graphite.

[0042] (Negative electrode active material layer) The negative electrode active material layer is the same as that described above, and the details have already been described, so they will not be repeated here.

[0043] (Separator) The separator is an electrically insulating porous film. The separator electrically isolates the positive electrode and the negative electrode. The separator may have a thickness of, for example, 5 to 30 μm. The separator may be composed of, for example, a porous polyethylene (PE) film, a porous polypropylene (PP) film, or the like. The separator may have a multi-layer structure. For example, the separator may be composed of a porous PP film, a porous PE film, and a porous PP film laminated in this order. The separator may have a heat-resistant layer on its surface. The heat-resistant layer includes a heat-resistant material. Examples of the heat-resistant material include metal oxide particles such as alumina, and high-melting point resins such as polyimide.

[0044] (electrolyte) The battery according to the embodiment of the present disclosure further comprises an electrolyte, and a non-aqueous electrolyte is particularly preferred.

[0045] ·solvent The non-aqueous electrolytic solution contains a solvent (non-aqueous solvent) and an electrolyte. Examples of the solvent (non-aqueous solvent) include N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(fluorosulfonyl)imide (DEME), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI), and 1-ethyl-2,3-dimethylimidazolium bis(fluorosulfonyl)imide (DEMI-FSI).

[0046] ·Electrolytes The electrolyte in the electrolytic solution may be, for example, a Li salt, such as lithium bis(fluorosulfonyl)imide (LiFSI), LiPF6 (lithium hexafluorophosphate), lithium tetrafluoroborate (LiBF4), or Li[N(CF3SO2)2]. The amount of the electrolyte may be, for example, 1.0 to 2.0 mol / L, and is preferably 1.0 to 1.5 mol / L.

[0047] The electrolytic solution may contain various additives, such as a thickener, a film-forming agent, a gas generating agent, etc., in addition to the solvent and the electrolyte. The electrolyte is typically a non-aqueous electrolytic solution that is liquid at room temperature (e.g., 25±10°C). The electrolytic solution is typically liquid in the environment in which the battery is used (e.g., a temperature environment of -20 to +60°C).

[0048] (Application) Applications of the batteries according to the embodiments of the present disclosure include, for example, power sources for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs). EXAMPLES

[0049] The present disclosure will be described below based on examples, but the present disclosure is not limited to these examples in any way.

[0050] <Example> Preparation of adhesive Adhesive 1 was obtained by mixing an olefin resin as a base agent, an isocyanate curing agent, and Ni-plated particles as a conductive assistant.

[0051] -Preparation of current collecting foil In the current collector foil manufacturing apparatus 100 shown in Fig. 1, adhesive 1 was used as the adhesive 40, a first aluminum foil (first Al foil) having a pinhole was used as the base foil 12, and a second aluminum foil (second Al foil) having a pinhole was used as the laminating foil 14. The thicknesses of the first Al foil and the second Al foil were both 40 µm. The line speed (conveying speed) was 15 m / min.

[0052] Adhesive 1 was applied to one surface of the first Al foil by gravure coating (coating step). This layer of adhesive 1 is referred to as the "first adhesive layer." Note that a gravure roll (elongated, 75 lines) was used as the coating roll 22A.

[0053] Next, the first Al foil on which the adhesive 1 (first adhesive layer) was applied was passed through a drying furnace 30 whose temperature was set to 150° C., thereby drying the adhesive 1 (drying step). Thereafter, the second Al foil was attached to the surface of the first Al foil conveyed to the pair of heated rolls 28A and 28B on which the adhesive 1 was applied, and heat-welded (heat-welding step), to obtain a foil in which the first Al foil and the second Al foil were heat-welded (hereinafter referred to as a "double Al foil"). The conditions for the pair of heated rolls 28A and 28B were as follows. Heat roll temperature: 90℃ Heat roll nip pressure: 0.45MPa

[0054] Next, the double Al foil was used as a base foil 12 in a current collector foil manufacturing apparatus 100 shown in Fig. 1, and a copper foil (Cu foil) was used as a lamination foil 14. The Cu foil had a thickness of 7.8 µm. The line speed (transport speed) was the same as above.

[0055] Adhesive 1 was applied to one surface of the double Al foil (the surface on the second Al foil side) by gravure coating (application step). This layer of adhesive 1 is referred to as the "second adhesive layer." Next, the double-layered Al foil on which the adhesive 1 (second adhesive layer) was applied was passed through a drying oven 30 whose temperature was set at 150° C., thereby drying the adhesive 1 (drying step). Thereafter, the double-layered Al foil was conveyed to the pair of heated rolls 28A and 28B, and the Cu foil was attached to the surface on which the adhesive 1 was applied, and heat-welded (heat-welding process). The conditions for the pair of heated rolls 28A and 28B were the same as above. In this way, the current collector foil of the embodiment was obtained. The thicknesses of the first adhesive layer and the second adhesive layer were both 3.0 μm.

[0056] <Comparative Example> -Preparation of current collecting foil In the current collector foil manufacturing apparatus 100 shown in Fig. 1, adhesive 1 was used as the adhesive 40, aluminum foil (Al foil) having pinholes was used as the base foil 12, and copper foil (Cu foil) was used as the lamination foil 14. The thickness of the Al foil was 40 µm, and the thickness of the Cu foil was 7.8 µm. The line speed (conveyance speed) was the same as in the example. The adhesive 1 was applied to one surface of the Al foil by gravure coating (coating step). The conditions for the coating roll 22A were the same as those in the example.

[0057] Next, the Al foil on which the adhesive 1 was applied was passed through a drying furnace 30 whose temperature was set at 150° C., thereby drying the adhesive 1 (drying step). Thereafter, the Cu foil was attached to the surface of the Al foil that had been conveyed to the pair of heated rolls 28A and 28B on which the adhesive 1 had been applied, and thermally welded (thermal welding process). The conditions for the pair of heated rolls 28A and 28B were the same as those in the example. In this way, a current collector foil of the comparative example was obtained. The thickness of the layer of adhesive 1 was 3.0 μm.

[0058] [Evaluation test] Pinhole inspection The current collector foils obtained in the examples and comparative examples were inspected for the presence or absence of pinholes having a diameter of 0.5 mm or less using an inspection machine. The results are shown in Table 1 below.

[0059] [Table 1]

[0060] It can be seen that the current collecting foil of the embodiment, in which two Al layers with pinholes are laminated, has a reduced number of pinholes compared to the current collecting foil of the comparative example, in which only one Al layer with pinholes is formed. [Explanation of symbols]

[0061] 10 Winding foil, 10A, 110 Current collector foil, 12 Base foil, 12A, 12B, 112 Positive electrode foil, 14 Laminated foil, 14A, 114 Negative electrode foil, 22A Coating roll, 22B Counter roll, 24, 26 Transport roll, 28A, 28B Heat roll pair, 30 Drying furnace, 40 Adhesive, 40A First intermediate layer, 40B Second intermediate layer, 140 Intermediate layer, 100 Current collector foil manufacturing device, 120, 120A, 120B, 1120 Pinhole

Claims

1. A 1-1 electrode foil having a pinhole; A first intermediate layer; A first-second electrode foil having a pinhole; A second intermediate layer; a second electrode foil, and One of the first electrode foil and the first-2 electrode foil, and the second electrode foil, is a positive electrode foil, and the other is a negative electrode foil.

2. A liquid battery comprising the current collector foil for a liquid battery according to claim 1, a positive electrode active material layer, a negative electrode active material layer, a separator, and an electrolyte.

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