Coated current collector, electrode, and power storage device

Abstract

[Problem] To provide a current collector that is capable of improving reliability when used in a power storage device. [Solution] According to one embodiment of the present invention, provided is a coated current collector comprising a substrate and a coating that is layered onto at least one surface of the substrate. The substrate includes aluminum or an aluminum alloy; the coating includes a polymer resulting from the polymerization of a monomer with an ethylenically unsaturated double bond; and the polymer is provided with a hydrocarbon chain derived from the ethylenically unsaturated double bond as a principal chain and a functional group with a coordinating property to aluminum ions as a side chain.

Description

Coated current collector, electrode, and electricity storage device

[0001] The present invention relates to a coated current collector, an electrode, and an electricity storage device.

[0002] Conventionally, various types of secondary batteries and electricity storage devices such as electrochemical capacitors have been developed. In this regard, Patent Document 1 discloses a negative electrode material useful for lithium ion secondary batteries. Furthermore, Patent Document 2 discloses an aluminum foil having a predetermined structure as an electrode current collector used for the positive or negative electrode of an electricity storage device.

[0003] JP 2019-114393 A International Publication No. 2020 / 203085 Pamphlet

[0004] Aluminum is a material that is readily available and has excellent processability, making it a suitable material for current collector applications. However, the inventors' investigations have revealed that there is still room for improvement in the reliability of aluminum current collectors when applied to electricity storage devices.

[0005] In view of the above circumstances, the present invention provides a current collector and the like that can improve reliability when applied to an electricity storage device.

[0006] According to one aspect of the present invention, there is provided a coated current collector comprising a substrate and a coating laminated on at least one surface of the substrate, wherein the substrate contains aluminum or an aluminum alloy, and the coating contains a polymer obtained by polymerizing a monomer having an ethylenically unsaturated double bond, the polymer comprising, as a main chain, a hydrocarbon chain derived from the ethylenically unsaturated double bond, and, as a side chain, a functional group capable of coordinating to an aluminum ion.

[0007] According to the above aspect, a current collector or the like is provided that can improve reliability when applied to an electricity storage device.

[0008] Fig. 1 is a cross-sectional view showing an example of a coated current collector of the present embodiment; Fig. 2 is a cross-sectional view showing an example of an electrode of the present embodiment; Fig. 3 is a cross-sectional view showing another example of an electrode of the present embodiment; Fig. 4 is a graph showing the results of oxidation resistance test 1 in the examples; Fig. 5 is a graph showing the results of oxidation resistance test 2 in the examples; Fig. 6 is a graph showing the results of measuring the element distribution of coated current collector 1.

[0009] Hereinafter, embodiments of the present invention will be described. Note that the various features shown in the following embodiments can be combined with each other. In addition, "to" in this specification means "above" or "below" unless otherwise specified. In addition, (meth)acrylic acid is a general term for methacrylic acid and acrylic acid (referring to methacrylic acid or acrylic acid).

[0010] That is, the coated current collector of this embodiment is as follows: A coated current collector comprising a substrate and a coating layered on at least one surface of the substrate, wherein the substrate contains aluminum or an aluminum alloy, and the coating contains a polymer obtained by polymerizing a monomer having an ethylenically unsaturated double bond, the polymer comprising a hydrocarbon chain derived from the ethylenically unsaturated double bond as a main chain and a functional group capable of coordinating to an aluminum ion as a side chain.

[0011] The outline and uses of such a coated current collector are described below. FIG. 1 is a cross-sectional view showing an example of a coated current collector of this embodiment. FIG. 2 is a cross-sectional view showing an example of an electrode of this embodiment. FIG. 3 is a cross-sectional view showing another example of an electrode of this embodiment. Note that these figures show the relationship between the layers in a schematic manner. Therefore, the thickness ratio of each layer is not limited to that shown in these figures.

[0012] As shown in Fig. 1, a coated current collector 100 of this embodiment includes a substrate 1 and a coating 2 laminated on at least one surface of the substrate 1. In a typical embodiment, the substrate 1 and the coating 2 are laminated so as to have a region where they contact each other, as shown in Fig. 1.

[0013] Such a coated current collector 100 is preferably used as a component constituting an electrode of an electricity storage device. The electrode 200 shown in FIG. 2 includes, in addition to the coated current collector 100 described above, an active material layer 3 provided on the side of the coating 2 opposite the side where the substrate 1 is present. That is, the electricity storage device of this embodiment may include an electrode formed from the coated current collector 100. The shapes of the coated current collector and electrode are not limited to these. For example, as in the electrode 300 shown in FIG. 3 , coatings (2A, 2B) and active material layers (3A, 3B) may be provided on both sides of the substrate 1. When coatings or the like are provided on both sides of the substrate 1 as shown in FIG. 3 , both coatings and active material layers may have the same composition. On the other hand, when coatings or the like are provided on both sides of the substrate 1 as shown in FIG. 3 , both coatings and active material layers may have different compositions.

[0014] The power storage device to which the electrode 200 or the electrode 300 is applied may be appropriately selected from known devices. For example, the power storage device to which the electrode of this embodiment is applied may be a secondary battery (lithium secondary battery or sodium secondary battery) or a capacitor. The electrode 200 or the electrode 300 may constitute the positive electrode of the above-mentioned power storage device, or the electrode 200 or the electrode 300 may constitute the negative electrode of the above-mentioned power storage device. As an example, assuming that the power storage device is a coin-type secondary battery, a coin-type secondary battery can be obtained by inserting a positive electrode, a negative electrode, and optionally a separator into a coin-type outer can, and then adding and sealing an electrolyte solution therein. The above-mentioned electrode 200 or the electrode 300 can be used as a constituent material of such a secondary battery. However, the shape of the power storage device is not limited thereto and may be any known shape, such as a cylindrical shape or a sheet shape.

[0015] The elements constituting the coated current collector and electrode of this embodiment will be described in detail below.

[0016] [Substrate 1] In this embodiment, the substrate 1 functions as a substrate for a current collector. Here, the substrate 1 is characterized by containing aluminum or an aluminum alloy. Aluminum is highly workable and is therefore a promising material for constituting an electricity storage device.

[0017] The substrate 1 may be in the form of a sheet, foil, or the like. The sheet or foil may be porous. The average thickness of the substrate 1 can be set appropriately depending on the contents of the applied power storage device, and may be, for example, in the range of 1 to 500 μm, 3 to 400 μm, or 5 to 300 μm. In this specification, the term "average thickness" refers to the average value of thicknesses measured at 20 arbitrary locations on a predetermined member (here, the substrate 1).

[0018] When an aluminum alloy is used as the base material 1, the metal to be combined with aluminum may be appropriately selected. For example, the combined metal may be copper, manganese, iron, etc. That is, the aluminum alloy used as the base material 1 of this embodiment may be, for example, an Al—Cu alloy, an Al—Mn alloy, an Al—Mn—Cu alloy, an Al—Fe—Cu alloy, etc.

[0019] [Coating 2] In this embodiment, coating 2 includes a polymer obtained by polymerizing a monomer having an ethylenically unsaturated double bond. Here, the polymer has a hydrocarbon chain derived from the ethylenically unsaturated double bond as its main chain and functional groups capable of coordinating to aluminum ions as its side chains.

[0020] That is, while aluminum and aluminum alloys used for the substrate 1 are considered to be industrially advantageous materials, the present inventors have come to realize the following problem. Specifically, it has been found that there is a concern that aluminum may be oxidized (ionized) during the use of a current collector containing aluminum, which may cause defects in the current collector. In response to this, the coating 2 of this embodiment uses a polymer that has the ability to coordinate to aluminum ions. This is thought to suppress the occurrence of the aforementioned defects and ultimately contribute to improving the reliability when applied to an electricity storage device.

[0021] The polymer used in the coating 2 has a structure in which a monomer having an ethylenically unsaturated double bond is polymerized. In a typical embodiment, the polymer has the following structural unit (I):

[0022]

[0023] In the structural unit (I), each symbol is as follows: １ and R ２ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. １ and R ２ may be linked to each other to form a ring structure including the main chain of the polymer. The ring structure here may be a 4- to 8-membered ring. １ and Y ２ are each independently a single bond or an alkylene group having 1 to 3 carbon atoms. ３ is a group selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, and a functional group having the ability to coordinate to aluminum. FG is a functional group having the ability to coordinate to an aluminum ion. n is the number of repeating structural units (I) in the polymer. There are no particular restrictions on the value of n, but the lower limit may be, for example, 50 or more, or 70 or more. There are also no particular restrictions on the upper limit of n, but it may be, for example, 20,000 or less, or 18,000 or less.

[0024] The functional group capable of coordinating to aluminum ions provided on the polymer may be various functional groups, but a typical example is a functional group containing a heteroatom. More specifically, the functional group capable of coordinating to aluminum ions may be selected from the group consisting of a carboxyl group, a hydroxyl group, a hydrosulfur group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, and an amino group. The amino group here may be either a primary amino group or a secondary amino group. In addition, R ３ When a functional group having the ability to coordinate to an aluminum ion is used as R ３ The functional group may be the same as or different from the functional group employed as FG.

[0025] Among the above, from the viewpoint of improving the availability of the polymer, the functional group capable of coordinating to aluminum ions is preferably a carboxyl group or a hydroxyl group. Examples of polymers having a carboxyl group include polymers of (meth)acrylic acid. Furthermore, as polymers having two carboxyl groups, polymers of maleic acid or fumaric acid may be used as the polymer constituting the coating 2. Examples of polymers having hydroxyl groups include polymers of vinyl alcohol (polyvinyl alcohol; PVA). The molecular weight of the above polymers can be set as appropriate. For example, the viscosity-average molecular weight Mv of the polymer may be in the range of 50,000 to 1,500,000.

[0026] The polymer may have a structural unit other than the structural unit (I) described above. In other words, the polymer contained in the coating 2 need only contain at least the structural unit (I), and does not necessarily have to be a homopolymer. When the polymer is a copolymer, the other monomer is appropriately selected from monomers capable of constituting a polymer, such as ethylene, propylene, cyclohexene, norbornene, etc.

[0027] In polymer, the proportion of structural unit (I) in all structural units can be appropriately set.On the other hand, from the viewpoint of enhancing the coordination effect to aluminum ion, the proportion of structural unit (I) in all structural units of polymer is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, particularly preferably 80 mol% or more, and particularly preferably 90 mol% or more.In addition, the proportion of structural unit (I) in all structural units of polymer may be 100 mol% (i.e., all structural units of polymer correspond to structural unit (I)).

[0028] Furthermore, the coating 2 may contain other polymers that do not fall under the category of the polymers described above. These other polymers can be selected as appropriate within a range that does not deviate from the intended function of the coating 2. For example, the coating 2 may contain, as other polymers, polyester resin, polyurethane resin, polyamide resin, polyvinyl chloride resin, polyether resin, acrylic resin, melamine resin, vinyl resin, phenolic resin, epoxy resin, urea resin, vinyl acetate resin, polybutadiene resin, vinyl chloride-vinyl acetate copolymer resin, fluororesin (including polyvinylidene fluoride, etc.), silicone resin, rosin, rosin ester, chlorinated polyolefin resin, modified chlorinated polyolefin resin, chlorinated polyurethane resin, cellulose-based resin, etc.

[0029] Coating 2 may contain a material other than the above-described polymer. In an exemplary embodiment, coating 2 may further contain a conductive material. By employing such an embodiment, electrical conduction between substrate 1 and active material layer 3 can be easily achieved when an electrode is fabricated, thereby providing a member with higher reliability.

[0030] The conductive material may be selected from known materials and may be an inorganic or organic material. In an exemplary embodiment, the conductive material may include one or more selected from the group consisting of carbon black, ketjen black, carbon nanotubes, graphene, and acetylene black. These materials are readily available and have excellent conductivity, making them suitable as materials for forming the coating 2.

[0031] When a conductive material is included in the coating 2, the content of the conductive material is appropriately set depending on the physical properties of the conductive material. For example, when the total mass of the coating 2 (solid content equivalent) is 100 parts by mass, the content of the conductive material may be in the range of 30 to 70 parts by mass, 35 to 65 parts by mass, or 40 to 60 parts by mass. The content value of the conductive material may also be smaller than the above range. For example, when the total mass of the coating 2 (solid content equivalent) is 100 parts by mass, the content of the conductive material may be in the range of 1 to 50 parts by mass. The content value of the conductive material may also be larger than the above range. For example, when the total mass of the coating 2 (solid content equivalent) is 100 parts by mass, the content of the conductive material may be in the range of 50 to 99 parts by mass.

[0032] Additionally, the coating 2 may contain any additives or the like to improve the physical properties of the coating.

[0033] The thickness of the coating 2 can be set appropriately depending on the type of electricity storage device to which it is applied, but it is typically preferable to set it to a thin film thickness. This increases the degree of freedom in designing the active material layer 3, which will be described later, and ultimately contributes to improving the capacity of the electricity storage device. As an example, the average thickness of the coating 2 is preferably less than 5 μm, more preferably less than 3 μm, and even more preferably less than 2 μm. There is no particular lower limit to the thickness of the coating 2, but an example is 0.5 μm or more.

[0034] [Active Material Layer 3] The type of active material layer 3 can be appropriately determined depending on requirements such as whether the electrode 200 or the like is used as a positive electrode or a negative electrode. The thickness of the active material layer 3 can also be appropriately determined depending on the requirements. In a typical example, the average thickness of the active material layer 3 is set in the range of 100 μm to 1 mm, but is not limited thereto and any thickness may be set.

[0035] For example, when the electrode 200 is used as a positive electrode, the active material layer 3 may contain a positive electrode active material and a binder resin. Examples of the positive electrode active material include lithium metal oxide compounds. Specifically, lithium cobalt oxide (LiCoO ２), lithium nickel oxide (LiNiO ２ ), lithium manganese oxide (LiMn ２ O ４ ), olivine-type lithium iron phosphate (LiFePO ４ Of course, the positive electrode active material is not limited to these, and various positive electrode active materials that are used in the field of electricity storage devices can be employed.

[0036] In addition, when the electrode 200 or the like is used as a negative electrode, the active material layer 3 may contain a negative electrode active material and a binder resin. Examples of the negative electrode active material include lithium, carbon materials such as graphite, graphene, hard carbon, and acetylene black; Li ４ Ti ５ O １２ Lithium titanium oxides such as Ti ｘ Nb ｙ O ｚ Of course, the negative electrode active material is not limited to these, and various negative electrode active materials that are used in the field of electricity storage devices can be used.

[0037] Examples of binder resins that can be used in the active material layer 3 include binders that are widely used in the field of electricity storage devices, such as polyacrylic acid, lithium polyacrylate, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, styrene butadiene rubber, polyvinyl alcohol, polyvinyl acetal, polyethylene oxide, polyethylene glycol, carboxymethyl cellulose, polyacrylonitrile, and polyimide. The active material layer 3 may also contain a polymer similar to the polymer contained in the coating 2.

[0038] In addition to the above-mentioned materials, the active material layer 3 may contain a conductive aid and various additives in any amount.

[0039] [Method for Manufacturing Coated Current Collector / Electrode] Next, an example of a method for manufacturing the coated current collector and electrode of this embodiment will be described.

[0040] The coated current collector of this embodiment is typically produced by the following method: (Step 11) Preparing a substrate 1 (Step 12) Forming a coating 2 on at least one surface of the substrate 1

[0041] In step 11, a substrate 1 (current collector) containing aluminum or an aluminum alloy as described above is prepared. Subsequently, in step 12, a coating 2 is formed on at least one surface of the prepared substrate 1.

[0042] The coating 2 is formed, for example, by preparing a solution (or slurry) containing the polymer described above, applying it to the surface of the substrate 1, and drying it. The application method here may be appropriately selected from known techniques. Examples of application methods include dip coating, spray coating, roll coating, doctor blade coating, gravure coating, screen printing, and casting. For the polymer-containing solution, the solvent may be appropriately selected from solvents that dissolve or disperse raw materials such as the polymer. The solvent here may be water or an organic solvent, or a mixture of water and an organic solvent. Specific examples of organic solvents include alcohols such as methanol, ethanol, 1-propanol, and 2-propanol; amide-based solvents such as 1-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide; and ketone-based solvents such as acetone, 2-butanone, and cyclohexanone.

[0043] The drying method may also be appropriately selected, and examples thereof include natural drying or air drying at reduced or normal pressure in an atmosphere at room temperature to a temperature close to the boiling point of each solvent.

[0044] By carrying out the above steps, a coated current collector (coated current collector 100) can be obtained.

[0045] The electrode of this embodiment is typically produced by the following method: (Step 21) Preparing a coated current collector 100 (Step 22) Forming an active material layer 3 on the side of the coated current collector 100 opposite to the side of the coating 2 where the substrate 1 is present

[0046] For (Step 21), a coated current collector 100 may be prepared by the method shown as (Step 12). Subsequently, in (Step 22), an active material layer 3 is formed on the coating 2. The active material layer 3 here can be formed by applying a solution or slurry containing a predetermined active material (positive electrode active material or negative electrode active material) to the coating 2 and drying the applied solution or slurry. The same solvents that can be used for the solution, the application method, and the drying method as those shown as (Step 12) can be used.

[0047] In this manner, a predetermined electrode (such as the electrode 200) can be obtained. In the case of a coated current collector or electrode, when a coating or an active material layer is provided on both sides of the substrate 1, the above-described treatment may be performed on both sides of the substrate 1.

[0048] Furthermore, it may be provided in the following aspects.

[0049] (1) A coated current collector comprising a substrate and a coating layered on at least one surface of the substrate, wherein the substrate contains aluminum or an aluminum alloy, and the coating contains a polymer obtained by polymerizing a monomer having an ethylenically unsaturated double bond, the polymer having a hydrocarbon chain derived from the ethylenically unsaturated double bond as a main chain and a functional group capable of coordinating to an aluminum ion as a side chain.

[0050] (2) The coated current collector according to (1) above, wherein the coating further contains a conductive material.

[0051] (3) The coated current collector according to (2) above, wherein the conductive material includes one or more selected from the group consisting of carbon black, ketjen black, carbon nanotubes, graphene, and acetylene black.

[0052] (4) The coated current collector according to any one of (1) to (3) above, wherein the functional group capable of coordinating to an aluminum ion is selected from the group consisting of a carboxyl group, a hydroxyl group, a hydrosulfur group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, and an amino group.

[0053] (5) The coated current collector according to any one of (1) to (4) above, wherein the polymer is a polymer of (meth)acrylic acid.

[0054] (6) The coated current collector according to any one of (1) to (5) above, wherein the coating has an average thickness of less than 5 μm.

[0055] (7) An electrode comprising the coated current collector according to any one of (1) to (6) above, and an active material layer provided on the side of the coating opposite to the side on which the substrate is present.

[0056] (8) An electricity storage device comprising the electrode according to (7) above. Of course, the invention is not limited to this.

[0057] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0058] [Preparation of Coated Current Collector 1] First, a slurry for forming a coating was obtained by mixing polyacrylic acid (manufactured by Sigma-Aldrich; viscosity average molecular weight Mv: 450,000 or less), carbon black (Denka Corporation, product name DENKA BLACK Li-400), and N-methyl-2-pyrrolidone (manufactured by Sigma-Aldrich, solvent) in a weight ratio of 1:1:10. On the other hand, aluminum foil manufactured by Fuchikawa Metals Co., Ltd., having a thickness of 15 to 20 μm, was used as a substrate. The above-mentioned slurry was coated with a 10 μm doctor blade, dried at 80° C. for 30 minutes, and then roll-pressed to form a coating having an average thickness of 2 μm on the substrate. A current collector having this coating layered on the substrate was obtained as coated current collector 1.

[0059] [Preparation of Coated Current Collector 2] Coated current collector 2 was obtained under the same conditions as those for [Coated Current Collector 1], except that the binder resin (polyacrylic acid) in [Coated Current Collector 1] was changed to polyvinylidene fluoride (manufactured by Kureha Corporation, product name: KF Polymer W#1300).

[0060] [Oxidation Resistance Test 1] The oxidation resistance of the resulting coated current collectors 1 and 2, as well as the aluminum foil (current collector) used as the substrate, was examined. The experimental procedure involved injecting the electrolyte into a three-electrode cell using various coated current collectors, lithium foil, and lithium foil as the working electrode, counter electrode, and reference electrode, respectively, followed by chronoamperometry. The electrode potential was increased from 3.6 V to 5.0 V (vs. Li / Li+) in 0.2 V increments at 60°C, and each potential was maintained for 10 hours. The results are shown in Figure 4. The electrolyte used here was propylene carbonate (PC) containing 1 M LiTFSI.

[0061] 4 is a graph showing the results of oxidation resistance test 1 in the examples. As can be seen from this graph, coated current collector 1 (PAA in the figure), which is formed with a coating using polyacrylic acid as a binder resin, can provide higher oxidation resistance than coated current collector 2 (PVdF in the figure) and aluminum foil (Bare in the figure). A hypothetical mechanism is also shown in FIG. 4, and it is assumed that the carboxyl groups of polyacrylic acid appropriately capture aluminum ions, thereby achieving such oxidation resistance.

[0062] [Oxidation Resistance Test 2] Using the same apparatus as in [Oxidation Resistance Test 1], the leakage current density was measured after each time period under fixed temperature conditions of 60° C. and electrode potential of 4.6 V. Fig. 5 is a graph showing the results of Oxidation Resistance Test 2 in the examples. In addition to the coated current collector 1 (PAA in the figure) using polyacrylic acid as the binder resin and the coated current collector 2 (PVdF in the figure) using polyvinylidene fluoride as the binder resin, the coated current collector 3 (PVA in the figure) using polyvinyl alcohol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name Polyvinyl Alcohol (n=1500 to 1800)) as the binder resin, the coated current collector 4 (CMC in the figure) using carboxymethyl cellulose (manufactured by Daicel Miraize, trade name CMC Daicel 2200) as the binder resin, and the coated current collector 5 (CMC in the figure) using polyacrylonitrile latex (LA133; MSE A coated current collector 5 (LA133 in the figure) made of polyallylamine (purchased from Nittobo Medical, product name PAA-05) and a coated current collector 6 (Polyallylamine in the figure) made of polyallylamine (purchased from Nittobo Medical, product name PAA-05) were also evaluated.

[0063] As can be seen from the results in Figure 5, when a binder resin (polymer) having a functional group, such as a carboxyl group or a hydroxyl group, in its side chain that has aluminum ion coordinating ability is used, high oxidation resistance is demonstrated. In particular, the coated current collector 1 using polyacrylic acid as the binder resin exhibited a current resistance of 0.2 μA cm even after 100 hours. －２ The leakage current density was within the following range, confirming the high oxidation resistance.

[0064] [Elemental Distribution of Coated Current Collector 1] In [Oxidation Resistance Test 2], the elemental distribution of the coated current collector 1 after 5 hours had elapsed was measured. A focused ion beam scanning electron microscope (SMF2000) manufactured by Hitachi High-Tech Science was used as the measuring instrument to measure the elemental distribution in the film thickness direction of the coated current collector. FIG. 6 is a graph showing the results of measuring the elemental distribution of the coated current collector 1. In FIG. 6, the positional relationship between the aluminum substrate and the coating is also shown along with the elemental distribution measurement results. As shown in FIG. 6, it can be seen that the abundance ratio of aluminum element decreases from the current collector surface toward the upper layer of the coating. Furthermore, as shown in FIG. 6, a significant amount of aluminum is no longer detected at a distance of approximately 0.5 μm from the current collector surface toward the upper layer of the coating.

[0065] The results of the above examples support the idea that by applying a polymer having a predetermined functional group as a coating, it is possible to provide a current collector or the like that can improve reliability when applied to an electricity storage device.

[0066] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.

[0067] 1: Base material, 2, 2A, 2B: Film, 3, 3A, 3B: Active material layer, 100: Current collector with film, 200: Electrode, 300: Electrode

Claims

1. A coated current collector comprising: a substrate; and a coating laminated on at least one surface of the substrate; wherein the substrate comprises aluminum or an aluminum alloy; and the coating comprises a polymer formed by polymerizing a monomer having an ethylenically unsaturated double bond, the polymer comprising, as a main chain, a hydrocarbon chain derived from the ethylenically unsaturated double bond, and, as a side chain, a functional group capable of coordinating to an aluminum ion.

2. A coated current collector according to claim 1, wherein the coating further contains a conductive material.

3. A coated current collector according to claim 2, wherein the conductive material comprises one or more selected from the group consisting of carbon black, ketjen black, carbon nanotubes, graphene, and acetylene black.

4. A coated current collector according to any one of claims 1 to 3, wherein the functional group capable of coordinating to aluminum ions is selected from the group consisting of a carboxyl group, a hydroxyl group, a hydrosulfur group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, and an amino group.

5. A coated current collector according to any one of claims 1 to 4, wherein the polymer is a polymer of (meth)acrylic acid.

6. A coated current collector according to any one of claims 1 to 5, wherein the coating has an average thickness of less than 5 μm.

7. An electrode comprising: a current collector with a coating according to any one of claims 1 to 6; and an active material layer provided on the side of the coating opposite to the side on which the substrate is present.

8. An electricity storage device comprising the electrode according to claim 7.

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