Current collector foil for liquid battery, and liquid battery

Abstract

The present invention provides a collector foil for a liquid-based battery capable of reducing the number of pinholes, and a liquid-based battery capable of suppressing the occurrence of liquid junction. A current collector foil for a liquid battery, in which a 1-1 electrode foil having a pinhole, a first interposer, a 1-2 electrode foil having a pinhole, a second interposer, and a second electrode foil are laminated in this order, one of the 1-1 electrode foil, the 1-2 electrode foil, and the second electrode foil is a positive electrode foil, and the other is a negative electrode foil.

Description

Technical Field

[0001] The present disclosure relates to a current collector foil for a liquid-based battery and a liquid-based battery. Background Art

[0002] Conventionally, a current collector foil for a liquid-system battery is used, which is formed by laminating a positive electrode foil and a negative electrode foil.

[0003] For example, Japanese Patent Application Laid-Open No. 2023-053669 discloses a bipolar current collector. The bipolar current collector includes a positive electrode current collector having an aluminum layer, a negative electrode current collector having a copper layer, and an intermediate layer between the aluminum layer and the copper layer. The thickness of the copper layer is 3 to 10 μm. The intermediate layer has a porous aluminum oxide portion and a nickel portion present in the pores of the aluminum oxide portion.

[0004] In addition, Japanese Patent Laid-Open No. 2021-136115 discloses a bipolar battery. The bipolar battery comprises a first component, a second component, and a stacked electrode body disposed therebetween. The stacked electrode body comprises: 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 disposed between the first current collector and the second current collector, and a plurality of power generation elements electrically connected in series between the first current collector and the second current collector via the bipolar current collector. The first current collector is disposed between the first component and the bipolar current collector. The second current collector is disposed between the second component and the bipolar current collector. The first current collector has a first joint. The second current collector has a second joint. When the battery is powered on, the heat generated by the first joint is greater than the heat generated by the second joint. The first component is a cooling component for cooling the first current collector. The cooling performance of the first component is higher than the cooling performance of the second component. Summary of the invention

[0005] As a collector foil for liquid batteries, a collector foil formed by laminating a positive electrode foil and a negative electrode foil through an intermediary layer agent is used. However, in the metal foil used for the positive electrode foil and the negative electrode foil, pinholes are sometimes generated during the manufacturing process. In addition, when a collector foil having pinholes in at least one of the positive electrode foil and the negative electrode foil is used for a liquid battery, a through hole penetrating the positive electrode foil, the intermediary layer, and the negative electrode foil is sometimes generated, and in the liquid battery, a liquid junction is generated through the through hole.

[0006] The present disclosure has been made in view of the above circumstances and provides a current collector foil for a liquid-based battery capable of reducing the number of pinholes reaching from a 1-1 electrode foil to a second electrode foil, and a liquid-based battery capable of suppressing the occurrence of liquid contact.

[0007] Means for solving the above-mentioned problems include the following.

[0008] <1> A collector foil for a liquid battery,

[0009] The 1-1 electrode foil having pinholes,

[0010] The first intermediary layer,

[0011] The first and second electrode foils with pinholes,

[0012] The second intermediate layer, and

[0013] Second electrode foil

[0014] Stacked in sequence,

[0015] The 1-1 electrode foil and the 1-2 electrode foil, and

[0016] The second electrode foil

[0017] One of them is the positive electrode foil and the other is the negative electrode foil.

[0018] <2> A liquid battery having <1> A current collector foil, a positive electrode active material layer, a negative electrode active material layer, a separator and an electrolyte solution for a liquid battery are described.

[0019] According to the present disclosure, there are provided a current collector foil for a liquid system battery capable of reducing the number of pinholes reaching from a 1-1 electrode foil to a second electrode foil, and a liquid system battery capable of suppressing the occurrence of liquid contact. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Hereinafter, features, advantages, and technical and industrial significance of exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings, wherein like numerals denote like elements.

[0021] Figure 1 It is a schematic cross-sectional view showing the structure of a current collector foil according to an embodiment of the present disclosure.

[0022] Figure 2 This is a schematic cross-sectional view showing the structure of a conventional current collector foil.

[0023] Figure 3 This is a schematic cross-sectional view showing a current collector foil manufacturing apparatus used for manufacturing the current collector foil according to the embodiment of the present disclosure. DETAILED DESCRIPTION

[0024] An embodiment as an example of the present disclosure will be described. These descriptions and examples are illustrative of the embodiments and do not limit the scope of the invention.

[0025] In addition, in this specification, the numerical range expressed using "to" means the range including these numerical values ​​as a lower limit and an upper limit.

[0026] In the numerical range recorded in stages in this specification, the upper limit of a certain stage numerical range can be replaced by the upper limit of another stage numerical range, and can also be replaced by the value shown in the embodiment. In addition, the lower limit of a certain stage numerical range can be replaced by the lower limit of another stage numerical range, and can also be replaced by the value shown in the embodiment.

[0027] In addition, regarding the content, "%" means "mass %" unless otherwise specified.

[0028] Each component may also contain a plurality of corresponding substances.

[0029] When the amount of each component in a composition is mentioned, when there are multiple substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of these multiple substances present in the composition.

[0030] "Process" is not limited to independent processes. Even if it cannot be clearly distinguished from other processes, it is also included in this term as long as the intended effect of the process can be achieved.

[0031] Collector foil for liquid battery

[0032] The collector foil for liquid battery of the embodiment of the present disclosure (hereinafter also referred to as "collector foil") is formed by sequentially stacking a 1-1 electrode foil with pinholes, a first intermediate layer, a 1-2 electrode foil with pinholes, a second intermediate layer and a second electrode foil.

[0033] Furthermore, one of the 1-1 electrode foil and the 1-2 electrode foil and the 2nd electrode foil is a positive electrode foil, and the other is a negative electrode foil. That is, when the 1-1 electrode foil and the 1-2 electrode foil are positive electrode foils, the 2nd electrode foil is a negative electrode foil, and when the 1-1 electrode foil and the 1-2 electrode foil are negative electrode foils, the 2nd electrode foil is a positive electrode foil.

[0034] That is, in the collector foil of the embodiment of the present disclosure, two or more layers of positive electrode foil having pinholes are stacked, and a negative electrode layer is stacked on one of the layers, or two or more layers of negative electrode foil having pinholes are stacked, and a positive electrode layer is stacked on one of the layers.

[0035] The collector foil of the embodiment of the present disclosure has the above structure, thereby reducing the number of pinholes from the 1-1 electrode foil to the 2nd electrode foil. As a result, when the collector foil is used in a liquid battery, the generation of through holes in the collector foil can be suppressed, and the generation of liquid junction in the liquid battery can be suppressed.

[0036] Conventionally, a collector foil is used in which a positive electrode foil and a negative electrode foil are bonded together via an intermediate layer (such as an adhesive layer). However, pinholes (small holes penetrating the metal foil) may be generated in the metal foil used for the positive electrode foil and the negative electrode foil during the manufacturing process.

[0037] For example Figure 2 As shown, a positive electrode foil 112 having a pinhole 1120 is used. When the current collector foil 110 obtained by laminating the positive electrode foil 112 and the negative electrode foil 114 through the intermediary layer 140 is used for a liquid battery, a through hole that penetrates all of the positive electrode foil 112, the intermediary 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 positive electrode foil 112 having the pinhole 1120, a hole may also be formed in the intermediary layer 140 formed on the pinhole 1120, that is, the pinhole 1120 is not blocked by the intermediary layer 140. In addition, if the current collector foil 110 obtained by laminating the negative electrode foil 114 to the positive electrode foil 112 and the intermediary layer 140 is used for a liquid battery, the electrolyte penetrates into the hole penetrating the positive electrode foil 112 and the intermediary layer 140, and the electrolyte is in contact with the negative electrode foil 114. If the battery is repeatedly charged and discharged in this state, the reaction with the electrolyte (for example, when copper foil is used as the negative electrode foil 114, Cu→Cu 2+ +2e - The reaction of the positive electrode foil 112 and the negative electrode foil 114 may also generate holes. As a result, through holes that completely penetrate the positive electrode foil 112, the intermediate layer 140, and the negative electrode foil 114 are formed.

[0038] In addition, a negative electrode foil with pinholes is used. When the collector foil obtained by laminating the negative electrode foil and the positive electrode foil through an intermediary layer is used for a liquid battery, a through hole that penetrates all of the positive electrode foil, the intermediary layer and the negative electrode foil is sometimes formed at the location of the pinhole in the positive electrode foil. Specifically, at the location of the negative electrode foil with pinholes, a hole is sometimes formed in the intermediary layer formed on the pinhole, that is, the pinhole is not blocked by the intermediary layer. Moreover, if the collector foil obtained by laminating the positive electrode foil to the negative electrode foil and the intermediary layer is used for a liquid battery, the electrolyte invades the hole that penetrates the negative electrode foil and the intermediary layer, and the electrolyte is in contact with the positive electrode foil. If the battery is repeatedly charged and discharged in this state, cracks sometimes occur in the positive electrode foil, and as a result, a through hole that completely penetrates the negative electrode foil, the intermediary layer and the positive electrode foil is formed.

[0039] Furthermore, in the current collector foil having the through-holes penetrating the positive electrode foil, the interlayer, and the negative electrode foil, one side and the other side of the current collector foil are connected through the through-holes, so that liquid contact occurs.

[0040] Therefore, in the current collector foil according to the embodiment of the present disclosure, the 1-1 electrode foil having pinholes, the first intermediary layer, the 1-2 electrode foil having pinholes, the second intermediary layer, and the second electrode foil are stacked in this order.

[0041] For example Figure 1 As shown, a collector foil 10A having a structure in which a positive electrode foil 12A having a pinhole 120A, a first intermediary layer 40A, a positive electrode foil 12B having a pinhole 120B, a second intermediary layer 40B, and a negative electrode foil 14A are sequentially stacked can be made. The positive electrode foil 12A and the positive electrode foil 12B have the pinhole 120A and the pinhole 120B, respectively, but 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 are unlikely to overlap. In other words, by stacking the positive electrode foil 12A having the pinhole 120A and the positive electrode foil 12B having the pinhole 120B, the number of pinholes reaching the negative electrode foil 14A from the positive electrode foil 12A can be reduced.

[0042] Thus, according to the collector foil of the embodiment of the present disclosure, the number of pinholes reaching the second electrode foil from the 1-1 electrode foil can be reduced. As a result, when the collector foil is used in a liquid battery, the generation of through holes in the collector foil can be suppressed, and the generation of liquid junction in the liquid battery can be suppressed.

[0043] 1-1 electrode foil and 1-2 electrode foil

[0044] In the collector foil of the embodiment of the present disclosure, one of the 1-1 electrode foil and the 1-2 electrode foil and the 2nd electrode foil having pinholes is a positive electrode foil, and the other is a negative electrode foil. That is, the 1-1 electrode foil and the 1-2 electrode foil having pinholes can be positive electrode foils or negative electrode foils. However, the positive electrode foil (especially Al foil) is more likely to have pinholes. From the viewpoint of reducing the number of pinholes from the 1-1 electrode foil to the 2nd electrode foil caused by the pinholes on the positive electrode, it is preferred that the 1-1 electrode foil and the 1-2 electrode foil are positive electrode foils.

[0045] Furthermore, the materials of the 1-1 electrode foil and the 1-2 electrode foil are not particularly limited as long as both are positive electrode foils or negative electrode foils. Therefore, the 1-1 electrode foil and the 1-2 electrode foil may be positive electrode foils of different materials, and may also be negative electrode foils of different materials. However, it is more preferred that the 1-1 electrode foil and the 1-2 electrode foil are foils of the same material.

[0046] In addition to the 1-1 electrode foil and the 1-2 electrode foil, the collector foil of the embodiment of the present disclosure may also include a foil having pinholes and having the same polarity as 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 stacked. 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 stacked.

[0047] In addition, a foil having the same polarity as the second electrode foil may be further provided. That is, when the second electrode foil is a negative electrode foil, two or more layers of negative electrode foil may be stacked, and when the second electrode foil is a positive electrode foil, two or more layers of positive electrode foil may be stacked.

[0048] Positive electrode foil

[0049] The positive electrode foil used in the embodiment of the present disclosure is preferably a conductive member made of a metal with good conductivity (eg, aluminum). The thickness of the positive electrode foil is preferably 10 μm to 100 μm, and more preferably 20 μm to 60 μm.

[0050] Negative electrode foil

[0051] On the other hand, the negative electrode foil is preferably a conductive member made of a metal with good conductivity (such as copper). The thickness of the negative electrode foil is preferably 1 μm to 20 μm, and more preferably 3 μm to 12 μm.

[0052] Intermediary Layer 1 and Intermediary Layer 2

[0053] The first intermediary layer and the second intermediary layer (hereinafter, referred to as "intermediary layer") of the collector foil of the embodiment of the present disclosure are not particularly limited as long as they are layers having the function of bonding the 1-1 electrode foil and the 1-2 electrode foil, and the 1-2 electrode foil and the 2nd electrode foil. As the intermediary layer, for example, a layer of an adhesive (adhesive layer) can be cited.

[0054] As the adhesive constituting the adhesive layer, for example, an adhesive having a curing agent (such as an isocyanate curing agent) added to a main agent (such as an olefin resin) is preferably used. In addition, a conductive auxiliary agent (such as particles with Ni plated on the surface) may be added to the adhesive.

[0055] The thickness of the interposer layer is not particularly limited, but is, for example, preferably 0.5 μm to 15 μm, and more preferably 1.0 μm to 10 μm.

[0056] Manufacturing method

[0057] Next, a method for producing a current collector foil according to an embodiment of the present disclosure will be described by taking an example and using drawings.

[0058] Figure 3 The collector foil of the embodiment of the present disclosure is schematically shown in FIG. Figure 3 The collector foil manufacturing device shown in the figure stacks the 1-1 electrode foil having pinholes and the 1-2 electrode foil having pinholes via the first intermediate layer. Figure 3 The current collector foil manufacturing apparatus shown can manufacture the current collector foil by laminating the second electrode foil on the first-second electrode foil side via the second intermediary layer.

[0059] The following specifically describes how to use Figure 3 The collector foil manufacturing device shown in the figure is a method for manufacturing the collector foil of the embodiment of the present disclosure. Furthermore, in the following, the 1-1 electrode foil having pinholes is the 1st aluminum foil (1st Al foil) as the positive electrode foil. The 1-2 electrode foil having pinholes is the 2nd aluminum foil (2nd Al foil) as the positive electrode foil. The 2nd electrode foil is a copper foil (Cu foil) as the negative electrode foil. The first intermediate layer and the second intermediate layer are respectively the first adhesive layer and the second adhesive layer.

[0060] (A1) First coating step

[0061] First, in Figure 3 In the current collector foil manufacturing apparatus 100 shown, the base foil 12 is a first Al foil, the bonding foil 14 is a second Al foil, and the adhesive 40 is an adhesive for forming a first adhesive layer.

[0062] The first Al foil as the base foil 12 is fed to a roller pair consisting of a coating roller 22A (e.g., a gravure roller) and an opposing roller 22B. A portion of the coating roller 22A is immersed in an adhesive 40. The adhesive 40 (adhesive for forming the first adhesive layer) attached to the surface of the coating roller 22A is applied (e.g., gravure coating) from the coating roller 22A to one surface of the base foil 12 (the first Al foil).

[0063] (A2) First Drying Step

[0064] Next, the base foil 12 (first Al foil) that has passed the contact position with the coating roller 22A is conveyed to the drying furnace 30 via the conveying roller 24. On the conveying path 30, the adhesive 40 on the base foil 12 (first Al foil) is heated in the drying furnace 30 and dried.

[0065] (A3) First thermal welding step

[0066] Next, the base foil 12 (first Al foil) that has passed through the drying furnace 30 is conveyed to a contact position with the heat roller pair 28A, 28B via the conveying roller 26. In the nip portion of the heat roller pair 28A, 28B, the laminating foil 14 (second Al foil) conveyed from another direction is laminating to the surface of the base foil 12 (first Al foil) coated with the adhesive 40. And by heating and pressurizing by the heat roller pair 28A, 28B, the base foil 12 (first Al foil) and the laminating foil 14 (second Al foil) are thermally fused via the adhesive 40 (first adhesive layer). In this way, as the winding foil 10, a foil in which the first Al foil and the second Al foil are thermally fused (hereinafter referred to as "double Al foil") is obtained.

[0067] Then, use Figure 3 The current collector foil manufacturing apparatus shown stacks Cu foils.

[0068] (B1) Second coating step

[0069] Specifically, in Figure 3 In the current collector foil manufacturing apparatus 100 shown, the double Al foil obtained above is used as the base foil 12 , the Cu foil is used as the bonding foil 14 , and the adhesive for forming the second adhesive layer is used as the adhesive 40 .

[0070] The double Al foil as the base foil 12 is fed to a roller pair consisting of a coating roller 22A (e.g., a gravure roller) and an opposing roller 22B. The adhesive 40 (adhesive for forming the second adhesive layer) attached to the surface of the coating roller 22A is applied (e.g., gravure coating) from the coating roller 22A to one surface of the base foil 12 (double Al foil).

[0071] (B2) Second Drying Step

[0072] Next, the base foil 12 (double Al foil) having passed the contact position with the coating roller 22A is conveyed to the drying oven 30 via the conveying roller 24. On the conveying path 30, the adhesive 40 on the base foil 12 (double Al foil) is heated in the drying oven 30 and dried.

[0073] (B3) Second heat welding step

[0074] Next, the base foil 12 (double Al foil) that has passed through the drying furnace 30 is conveyed to a contact position with the heat roller pair 28A, 28B via the conveying roller 26. In the nip portion of the heat roller pair 28A, 28B, the laminating foil 14 (Cu foil) conveyed from another direction is laminated to the surface of the base foil 12 (double Al foil) coated with the adhesive 40. And by heating and pressurizing by the heat roller pair 28A, 28B, the base foil 12 (double Al foil) and the laminating foil 14 (Cu foil) are thermally fused via the adhesive 40 (second adhesive layer).

[0075] Through these processes, as the winding foil 10, a current collector foil is manufactured in which the first Al foil, the second Al foil, and the Cu foil are laminated via the first adhesive layer and the second adhesive layer, respectively.

[0076] Furthermore, the heating temperature in the first drying process and the second drying process (the temperature in the drying furnace 30 in Figure 3 ) can be adjusted according to the material of the interlayer used. For example, it is preferably 80°C or higher and 200°C or lower, and more preferably 100°C or higher and 180°C or lower.

[0077] In addition, the heating temperature in the first thermocompression bonding process and the second thermocompression bonding process ( Figure 3 the temperature of the hot roll pairs 28A and 28B in

[0078] ) can be adjusted according to the material of the interlayer 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. Figure 3 In addition, the pressure applied in the first thermocompression bonding process and the second thermocompression bonding process (

[0079] the clamping pressure formed by the hot roll pairs 28A and 28B in

[0080] ) is preferably, for example, 0.20 MPa or higher and 0.70 MPa or lower. More preferably, it is 0.30 MPa or higher and 0.60 MPa or lower.

[0081] Positive electrode active material layer

[0082] The positive electrode mixture layer contains a positive electrode active material and may also contain, for example, a binder.

[0083] As the positive electrode active material, for example, lithium nickel cobalt manganese composite oxide (hereinafter sometimes simply referred to as "LNCM") can be cited. The simplest LNCM is represented by the following general formula: LiNi x Co y Mn z O 2 (where x, y, and z in the formula are 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1). In addition to Li, Ni, Co, and Mn, LNCM may also contain other additive elements, such as transition metal elements other than Ni, Co, and Mn, and typical metal elements other than Li. LNCM has a layered crystal structure. LNCM can account for more than 50% by mass of the entire positive electrode active material, for example, 80 to 100% by mass. The positive electrode active material may also be composed only of LNCM.

[0084] Examples of other positive electrode active materials include lithium nickel composite oxides, lithium cobalt composite oxides, and lithium nickel manganese composite oxides.

[0085] Examples of the binder contained in the positive electrode mixture layer include vinyl halide resins such as polyvinylidene fluoride (PVdF).

[0086] The positive electrode mixture layer may further contain other components, such as a conductive material, etc. Examples of the conductive material include hardly graphitizable carbon, graphitizable carbon such as carbon black, and graphite.

[0087] Negative electrode active material layer

[0088] The negative electrode active material layer uses the negative electrode active material layer described above, and its details have been explained, so they are omitted here.

[0089] Diaphragm

[0090] The separator is an electrically insulating porous film. The separator electrically isolates the positive electrode and the negative electrode. The thickness of the separator may be, for example, 5 to 30 μm. The separator may be composed of, for example, a porous polyethylene (PE) film, a porous polypropylene (PP) film, etc. The separator may also have a multilayer structure. For example, the separator may be composed of a porous PP film, a porous PE film, and a porous PP film stacked in this order. The separator may also have a heat-resistant layer on its surface. The heat-resistant layer contains 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.

[0091] Electrolyte

[0092] The battery according to the embodiment of the present disclosure further comprises an electrolyte solution, and a non-aqueous electrolyte solution is particularly preferred.

[0093] Solvents

[0094] The non-aqueous electrolyte solution contains a solvent (non-aqueous solvent) and an electrolyte.

[0095] Examples of the solvent (non-aqueous solvent) include N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(fluorosulfonyl)imide (DEME), 1-ethyl-3-methylimidazole bis(fluorosulfonyl)imide (EMI), and 1-ethyl-2,3-dimethylimidazole bis(fluorosulfonyl)imide (DEMI-FSI).

[0096] Electrolytes

[0097] Examples of the electrolyte in the electrolytic solution include Li salts. Examples of the Li salts include lithium bis(fluorosulfonyl)imide (LiFSI), LiPF 6 (lithium hexafluorophosphate), lithium tetrafluoroborate (LiBF 4 ), Li[N(CF3 SO 2 ) 2 ]wait.

[0098] The amount of the electrolyte may be, for example, 1.0 to 2.0 mol / L, and preferably 1.0 to 1.5 mol / L.

[0099] In addition to the solvent and the electrolyte, the electrolyte may also contain various additives, such as a thickener, a film-forming agent, a gas generator, etc. Typically, the electrolyte is a non-aqueous electrolyte that is liquid at room temperature (e.g., 25±10°C). Typically, the electrolyte is liquid in the battery's operating environment (e.g., a temperature environment of -20 to +60°C).

[0100] use

[0101] Examples of applications of the battery according to the embodiment of the present disclosure include power sources for hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), battery electric vehicles (BEV), and the like.

[0102] Hereinafter, the present disclosure will be described based on examples, but the present disclosure is not limited to these examples at all.

[0103] Preparation of adhesive

[0104] An adhesive 1 was obtained by mixing an olefin resin as a main agent, an isocyanate curing agent, and Ni-plated particles as a conductive auxiliary agent.

[0105] Production of collector foil

[0106] As Figure 3 The adhesive 40 in the current collector foil manufacturing apparatus 100 shown in the figure uses the adhesive 1, the first aluminum foil (first Al foil) having pinholes is used as the base foil 12, and the second aluminum foil (second Al foil) having pinholes is used as the bonding foil 14. The thickness of the first Al foil and the second Al foil is 40 μm. In addition, the production line speed (transport speed) is 15 m / min.

[0107] Adhesive 1 is applied to one surface of the first Al foil by gravure coating (coating step). The layer formed by the adhesive 1 is referred to as a “first adhesive layer.” A gravure roll (stretch type, 75 lines) is used as the coating roll 22A.

[0108] Next, the first Al foil coated with the adhesive 1 (first adhesive layer) is passed through a drying furnace 30 set at a temperature of 150° C., thereby drying the adhesive 1 (drying step).

[0109] Then, the first Al foil fed to the heat roller pair 28A, 28B is bonded to the second Al foil on the surface coated with the adhesive 1 and heat-fused (heat-fusion step), thereby obtaining a foil in which the first Al foil and the second Al foil are heat-fused (hereinafter referred to as "double Al foil"). The conditions of the heat roller pair 28A, 28B are as follows.

[0110] Temperature of hot roller pair: 90℃

[0111] The clamping pressure of the hot roller pair: 0.45MPa

[0112] Next, double Al foil was used as Figure 3 The base foil 12 in the current collector foil manufacturing apparatus 100 shown above uses a copper foil (Cu foil) as the bonding foil 14. The thickness of the Cu foil is 7.8 μm. The line speed (conveying speed) is the same as above.

[0113] Adhesive 1 is applied to one surface (the surface on the second Al foil side) of the double Al foil by gravure coating (coating step). The layer formed by the adhesive 1 is referred to as a "second adhesive layer".

[0114] Next, the double Al foil coated with the adhesive 1 (second adhesive layer) is passed through a drying furnace 30 set at a temperature of 150° C., thereby drying the adhesive 1 (drying step).

[0115] Then, the double Al foil conveyed to the hot roller pair 28A, 28B is bonded with the Cu foil on the surface coated with the adhesive 1 and heat-fused (heat-fusion process). The conditions of the hot roller pair 28A, 28B are the same as those described above. In this way, the collector foil of the embodiment is obtained. The thickness of the first adhesive layer and the second adhesive layer are both 3.0 μm.

[0116] Comparative Example

[0117] Production of collector foil

[0118] As Figure 3 The adhesive 40 in the current collector foil manufacturing device 100 shown in the figure uses the adhesive 1, the aluminum foil (Al foil) having pinholes is used as the base foil 12, and the copper foil (Cu foil) is used as the bonding foil 14. The thickness of the Al foil is 40 μm, and the thickness of the Cu foil is 7.8 μm. In addition, the production line speed (transport speed) is the same as that of the embodiment.

[0119] Adhesive 1 was applied to one surface of the Al foil by gravure coating (coating step). The conditions of the coating roller 22A were the same as those in the example.

[0120] Next, the Al foil coated with the adhesive 1 is passed through a drying furnace 30 set at a temperature of 150° C. to dry the adhesive 1 (drying step).

[0121] Then, the Al foil fed to the heat roller pair 28A, 28B was bonded to the Cu foil on the surface coated with the adhesive 1 and heat-fused (heat-fusion step). The conditions of the heat roller pair 28A, 28B were the same as those of the embodiment. Thus, the collector foil of the comparative example was obtained. The thickness of the layer of the adhesive 1 was 3.0 μm.

[0122] Evaluation test

[0123] Pinhole inspection

[0124] The current collector foils obtained in the examples and comparative examples were inspected using an inspection machine to see if there were pinholes with a diameter of 0.5 mm or less. The results are shown in Table 1 below.

[0125] Table 1

[0126]

[0127] It is found that the collector foil of the example in which two Al layers having pinholes are stacked can reduce the number of pinholes compared to the collector foil of the comparative example in which only one Al layer having pinholes is formed.

Claims

1. A collector foil for a liquid battery, The 1-1 electrode foil having pinholes, The first intermediary layer, The first and second electrode foils with pinholes, The second intermediate layer, and Second electrode foil Stacked in sequence, The 1-1 electrode foil and the 1-2 electrode foil, and The second electrode foil One of them is the positive electrode foil and the other is the 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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