Method for manufacturing electrode for energy storage device and manufacturing equipment for electrode for energy storage device

Abstract

To provide an electrode for an energy storage device that has an active material layer with a novel structure consisting mainly of carbon nanostructure and that can achieve high battery performance.SOLUTION: An electrode for an energy storage device comprises a metal substrate that constitutes a current collector and has a micro-uneven structure formed on its surface, and an active material layer consisting mainly of carbon nanostructure composed of nanographene and amorphous carbon, and densely covering the surface of the uneven structure, in which metal atoms involved in the charging and discharging of the energy storage device are deposited on the surface when the device is charged.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The technology of the present disclosure relates to an electrode for a power storage device, a secondary battery, a method for manufacturing an electrode for a power storage device, and a manufacturing apparatus for an electrode for a power storage device.

Background Art

[0002] As a charge-dischargeable power storage device, for example, a secondary battery is known. Generally, in an electrode for a power storage device, an active material layer composed of a substance involved in the charge-discharge reaction of the power storage device is formed on the surface of a current collector. For example, Patent Documents 1 and 2 below disclose a lithium-ion secondary battery having an active material layer containing lithium (Li) as a positive electrode and an active material layer containing carbon (C) as an active material in the form of graphite, carbon nanotubes, or the like as a negative electrode.

[0003] Generally, it is known that the configuration of the active material layer greatly affects the battery performance of the power storage device. For example, there is also a technical finding that the battery performance of a power storage device is improved when a carbon nanostructure such as a carbon nanotube wall is applied to the active material layer as in Patent Document 2 rather than when graphite is applied to the active material layer as in Patent Document 1.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a conventional configuration in which graphite is applied to the active material layer as in Patent Document 1, it may become impossible to sufficiently achieve the high battery performance target required for power storage devices in the future.

[0006] On the other hand, when applying carbon nanowalls to the active material layer as in Patent Document 2, it takes time to manufacture the carbon nanowalls, and the manufacturing cost of the power storage device may increase significantly. Further, when the electrode with carbon nanowalls applied to the active material layer is wound in a roll shape for transportation or storage during the manufacturing process of the power storage device, the carbon nanowalls on the surface may be broken or fall off due to compressive stress or shear stress.

[0007] As described above, there is still room for improvement in the electrodes for power storage devices that use carbon as the active material. The present disclosure aims to provide an electrode for a power storage device having a structure different from the conventional one and including an active material layer capable of realizing high battery performance.

Means for Solving the Problems

[0008] While repeatedly researching carbon nanostructures applicable to the active material layer, the inventor of the present invention succeeded in developing an electrode for a power storage device that can be easily manufactured by a method different from the conventional one and can dramatically improve battery performance. The technology of the present disclosure can be realized, for example, in the following forms.

[0009] One form of the present invention is provided as an electrode for a power storage device. The electrode for a power storage device of this form includes a metal substrate that constitutes a current collector and has a fine uneven structure formed on its surface, and a carbon nanostructure composed of nanographene and amorphous carbon as a main component, and is formed so as to densely cover the surface of the uneven structure, and an active material layer in which metal atoms involved in charging and discharging of the power storage device are deposited on the surface during charging of the power storage device.

[0010] According to the electrode for a power storage device of this form, since a carbon nanostructure composed of nanographene and amorphous carbon is used as an active material, the battery performance of the power storage device can be enhanced. Further, since the surface of the active material layer is formed uneven, the surface area of the active material layer is increased, the amount of metal deposited during charging of the power storage device can be increased, and the charging capacity of the power storage device can be enhanced. Also, due to the uneven structure of the active material layer, a large number of convex portions are formed on the surface of the active material layer, so that the deposition of metal on the surface of the active material layer during charging of the power storage device is promoted. Therefore, the battery performance of the power storage device can be further enhanced. In addition, since the active material layer is formed like a thin film that densely covers the surface of the metal substrate, unlike carbon nanotubes that grow so as to extend from the surface of the metal substrate, it can be suppressed from being broken or falling off in the manufacturing process of the power storage device.

[0011] The present invention can be realized in various forms other than an electrode for a power storage device, a secondary battery, a method for manufacturing an electrode for a power storage device, and an apparatus for manufacturing an electrode for a power storage device. The present invention can be realized, for example, in forms such as various power storage devices other than secondary batteries, an active material layer used in the power storage device, a method for manufacturing the active material layer, an apparatus for manufacturing the active material layer, and the like. Further, the present invention can also be realized in forms such as a device or a system including a power storage device.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of an electrode for a power storage device, a secondary battery, a method for manufacturing an electrode for a power storage device, and a manufacturing apparatus for an electrode for a power storage device according to the present invention will be described with reference to the drawings.

[0014] 1. Embodiment: 1-1. Configuration of a secondary battery and its electrodes: FIG. 1 is a schematic diagram showing the configuration of a secondary battery 10 according to the present embodiment. In FIG. 1, for convenience, the container 11 is illustrated by a dashed line, and the separator 15 is illustrated by a two-dot chain line.

[0015] The secondary battery 10 is an aspect of a rechargeable power storage device and is a lithium-ion secondary battery in which lithium (Li) ions are involved in charge and discharge. The secondary battery 10 includes a container 11, an electrolytic solution 12, a separator 15, a first electrode 20, and a second electrode 30.

[0016] Container 11 has an internal space filled with electrolyte 12. Container 11 is hermetically configured with a material that is less reactive to electrolyte 12. Electrolyte 12 has the property of being able to transfer metal ions involved in charge and discharge between the first electrode 20 and the second electrode 30.

[0017] In this embodiment, electrolyte 12 is composed of a solution in which a lithium salt is dissolved in an organic solvent and can transfer lithium ions. As the lithium salt of electrolyte 12, for example, lithium hexafluorophosphate (LiPF6) can be used. As the organic solvent, for example, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), etc. can be used.

[0018] Separator 15 divides the internal space of container 11 into a first electrode chamber 16 in which the first electrode 20 is accommodated and a second electrode chamber 17 in which the second electrode 30 is accommodated. Separator 15 is composed of, for example, a thin film member such as a resin film or non-woven fabric having a porous structure and has electrical insulation and ion conductivity. Separator 15 electrically insulates the first electrode 20 and the second electrode 30 and allows metal ions transmitted through electrolyte 12 to pass through.

[0019] The first electrode 20 corresponds to the electrode for the power storage device of this embodiment. In the following description, the first electrode 20 is also simply referred to as "electrode 20". In the secondary battery 10 of this embodiment, electrode 20 constitutes the negative electrode. Electrode 20 includes a metal substrate 21 and an active material layer 22.

[0020] The metal substrate 21 constitutes a current collector. In this embodiment, the metal substrate 21 is composed of a metal foil of copper (Cu) or a Cu alloy. By configuring the metal substrate 21 with Cu or a Cu alloy, high battery performance can be achieved in the power storage device.

[0021] In other embodiments, the metal substrate 21 may be made of a metal other than Cu or a Cu alloy. The metal substrate 21 may be made of, for example, nickel (Ni), a Ni alloy, aluminum (Al), an Al alloy, or the like. The metal substrate 21 does not necessarily have to be made of a metal foil, and may be made of, for example, a thin metal plate. The metal substrate 21 does not necessarily have to be configured in a flat plate shape, and may be bent into various shapes such as a cylindrical shape or a corrugated shape. The metal substrate 21 may have a porous structure.

[0022] The active material layer 22 is provided on both the first surface 21a and the second surface 21b of the metal substrate 21. Details of the configuration of the active material layer 22 will be described later. As will be described later, since a fine concavo-convex structure is formed on the first surface 21a and the second surface 21b of the metal substrate 21, the first surface 21a and the second surface 21b are illustrated by broken lines in FIG. 1 for convenience.

[0023] The second electrode 30 constitutes the positive electrode of the secondary battery 10. The second electrode 30 includes a positive electrode current collector 31 and a positive electrode active material layer 32. The positive electrode current collector 31 is made of, for example, a metal foil such as aluminum (Al) or titanium (Ti). The positive electrode current collector 31 may be made of another metal or may have a form other than a metal foil. The positive electrode current collector 31 does not necessarily have to be configured in a flat shape, and may be bent into various shapes such as a cylindrical shape or a corrugated shape.

[0024] The positive electrode active material layer 32 is formed on each of the first surface 31a and the second surface 31b of the positive electrode current collector 31. The positive electrode active material layer 32 contains a positive electrode active material containing metal atoms involved in charge and discharge, a conductive assistant, and a binder. The positive electrode active material layer 32 may contain a thickener.

[0025] In this embodiment, the metal atoms involved in charge and discharge are Li atoms. As the positive electrode active material, for example, a ternary material can be used, and lithium cobaltate (LiCoO2), lithium manganate (LMO), lithium nickelate (NCA), or the like can be used.

[0026] As the conductive assistant, for example, acetylene black or carbon black can be used. As the binder, for example, polyvinylidene fluoride (PVDF) or styrene-butadiene rubber (SBR) can be used. As the thickener, for example, carboxymethyl cellulose (CMC) can be used.

[0027] Referring to FIG. 2, the configuration of the active material layer 22 of the electrode 20 will be described. FIG. 2 is a schematic cross-sectional view schematically showing the metal substrate 21 and the active material layer 22 in an arbitrary cross-section along the thickness direction of the metal substrate 21. In FIG. 2, the first surface 21a of the metal substrate 21 is shown, but the configuration described below is common to both the first surface 21a and the second surface 21b of the metal substrate 21.

[0028] On the first surface 21a and the second surface 21b of the metal substrate 21, a fine concavo-convex structure 23 in micron units is formed. The active material layer 22 is formed in a thin film shape so as to densely cover the surface of the concavo-convex structure 23. The average thickness of the active material layer 22 may be, for example, 0.1 μm to 15.0 μm.

[0029] The active material layer 22 has a surface concavo-convex structure 24 which is a concavo-convex structure finer than the concavo-convex structure 23 of the metal substrate 21. In order to improve the battery performance of the power storage device, it is preferable that a plurality of granular convex portions 24t having a width of 0.1 μm or more and 10.0 μm or less are densely distributed on the surface of the active material layer 22 when viewed in the thickness direction of the metal substrate 21. The "width of the convex portion 24t" means the maximum value among the widths measured in all directions orthogonal to the thickness direction of the metal substrate 21 for one convex portion 24t. In addition, in the formation process of the concavo-convex structure 23 of the metal substrate 21 and the active material layer 22, minute cavities 25 may be formed inside.

[0030] The active material layer 22 is mainly composed of a carbon nanostructure composed of nanographene and amorphous carbon. The active material layer 22 has a structure in which particles of nanographene or amorphous carbon are deposited. The particles of nanographene or amorphous carbon include those having a spherical shape and those having a plate-like shape. The convex portions 24t of the active material layer 22 described above include those formed by the particles alone and those formed by randomly aggregating.

[0031] The active material layer 22 is formed by plasma treatment described later. However, hydroxyl groups may remain as impurities mixed in by the plasma treatment inside the active material layer 22. The method for forming the active material layer 22 will be described in the explanation of the manufacturing method of the secondary battery 10 described later.

[0032] 1-2. Charge and discharge reactions in the power storage device: The chemical reactions during charge and discharge in the secondary battery 10 can be represented by, for example, the following reaction formulas. When the positive electrode material is LiCoO2, the reaction formula at the second electrode 30 which is the positive electrode is represented by the following formula (1). x represents the ratio of reacting atoms and is a real number greater than 0 and less than 1. Li 1-x CoO2+ xLi + + xe - ⇔ LiCoO2…(1)

[0033] When the metal involved in charge and discharge is Li, the reaction formula at the electrode 20 which is the negative electrode is represented by the following formula (2). In the active material layer 22 mainly composed of a carbon nanostructure, during charging of the secondary battery 10, Li is deposited on the surface of the active material layer 22 of the electrode 20 by the reaction shown in formula (2). Li + + e - ⇔ Li …(2)

[0034] In the case of the conventional negative electrode configuration in which graphite is disposed as an active material on the surface of a flat metal substrate, in principle, one lithium ion is occluded per six carbon atoms during charging, and lithium carbide (LiC6) is formed. Therefore, the reaction formula for this conventional configuration as a comparative example is represented as the following formula (3). xLi+ + C6+ xe - ⇔ Li x C6…(3)

[0035] As shown in the formula (3) of the above comparative example, in the case of an electrode having a conventional configuration using graphite as a negative electrode active material, the number of lithium ions that can be occluded by charging is determined by the number of carbon atoms contained in the active material layer. On the other hand, according to the secondary battery 10 having the electrode 20 of the present embodiment, as shown in the above formula (2), theoretically, as long as Li can be deposited on the electrode 20, charging is possible. Therefore, according to the electrode 20 of the present embodiment, a higher charging capacity can be realized in a power storage device such as the secondary battery 10.

[0036] Also, as described above, in the electrode 20 of the present embodiment, the active material layer 22 is formed so as to cover the surface of the concavo-convex structure 23 of the metal substrate 21 as described above, and has a surface concavo-convex structure 24 finer than the concavo-convex structure 23 of the metal substrate 21. As a result, the surface area of the surface of the active material layer 22 where Li can be deposited is significantly increased. Therefore, according to the electrode 20 of the present embodiment, a high charging capacity can be obtained in the secondary battery 10.

[0037] On the surface of the active material layer 22, a large number of convex portions 24t constituting the surface concavo-convex structure 24 are formed. According to the nucleation theory, since Li is likely to be deposited starting from the convex portions 24t on the surface of the active material layer 22, the deposition of Li on the surface of the active material layer 22 is promoted. Therefore, according to the electrode 20 of the present embodiment, battery performance such as the charging capacity and specific capacity of the secondary battery 10 can be improved.

[0038] In addition, if the convex portions 24t are uniformly distributed on the surface of the active material layer 22, Li can be uniformly deposited on the surface of the active material layer 22. Therefore, it is possible to suppress the generation of dendrites on the electrode 20 due to repeated charge and discharge of the secondary battery 10, and it is possible to suppress damage and deterioration of the power storage device caused by dendrites.

[0039] 1-3. Method for manufacturing a secondary battery: FIG. 3 is a process flow diagram showing the manufacturing process of the secondary battery 10. Processes P1 to P5 are the manufacturing processes of the electrode 20. In the present embodiment, a plurality of electrodes 20 are continuously manufactured.

[0040] In process P1, the base material BM of the metal substrate 21 is prepared. In the present embodiment, the base material BM has a strip-shaped configuration in which a plurality of portions are connected so that a plurality of electrodes 20 can be continuously manufactured. The fine concavo-convex structure 23 on the surface described above is not yet formed on the base material BM, and the surface of the base material BM is configured to be flat.

[0041] In processes P2 to P4, the active material layer 22 is formed on the surface of the base material BM by the plasma treatment described below. In this plasma treatment, a fine concavo-convex structure 23 is formed on the surface of the base material BM, and the active material layer 22 is formed so as to cover the surface of the concavo-convex structure 23.

[0042] In the present embodiment, the plasma treatment is performed by the plasma treatment apparatus 50 of the first configuration example or the plasma treatment apparatus 50a of the second configuration example. The plasma treatment apparatuses 50 and 50a are each an example of an apparatus for forming the active material layer 22 on the base material BM of the metal substrate 21, and correspond to the manufacturing apparatus of the electrode 20. Below, after explaining the plasma treatment apparatus 50 of the first configuration example, the plasma treatment apparatus 50a of the second configuration example will be explained, and then the contents of processes P2 to P4 for the plasma treatment will be explained.

[0043] FIG. 4 is a schematic diagram showing the configuration of a plasma processing apparatus 50 according to the first configuration example. The plasma processing apparatus 50 performs plasma processing for forming the active material layer 22 on a belt-like base material BM conveyed in the longitudinal direction. The plasma processing apparatus 50 includes a reaction chamber 51, a liquid supply unit 52, a liquid discharge unit 53, a base material conveyance unit 55, and a plasma generation unit 60.

[0044] The reaction chamber 51 is configured to be liquid-tight so that the solution LQ can be stored inside. Further, the reaction chamber 51 is configured to be airtight so that plasma can be generated in the region above the stored solution LQ.

[0045] The solution LQ contains alcohols. The alcohol concentration of the solution LQ may be, for example, about 50 to 100% by mass. The C atoms contained in the solution LQ constitute the active material of the active material layer 22. The alcohols contained in the solution LQ may be, for example, primary alcohols. In the present embodiment, the alcohol contained in the solution LQ is ethanol (C2H6O).

[0046] The alcohol in the solution LQ is not limited to ethanol. In other embodiments, the alcohol in the solution LQ may be, for example, butanol (C4H 10 O) or hexanol (C6H 14 O). Further, the solution LQ may be a mixture of multiple types of alcohols. The solution LQ may be, for example, a mixture of ethanol and methanol (CH3OH). In addition, the solution LQ may be a mixture of hydrocarbons such as hexane (C6H 14 ) or benzene (C6H6) and alcohols such as ethanol.

[0047] The liquid supply unit 52 and the liquid discharge unit 53 are connected to the lower part of the reaction chamber 51. The liquid supply unit 52 supplies the solution LQ to the reaction chamber 51, and the liquid discharge unit 53 discharges the solution LQ to the outside of the reaction chamber 51. During plasma processing, by controlling the liquid supply unit 52 and the liquid discharge unit 53, the amount of the solution LQ stored in the reaction chamber 51 and the concentration of the solution LQ are controlled to predetermined target values.

[0048] The substrate conveyance unit 55 conveys the substrate BM of the metal substrate 21. As described above, in this embodiment, the substrate BM of the metal substrate 21 is in a strip shape, and the substrate conveyance unit 55 conveys the substrate BM in its longitudinal direction. In FIG. 4, an arrow indicating the conveyance direction MD of the substrate BM is shown.

[0049] The substrate conveyance unit 55 includes a substrate supply unit 56, a plurality of conveyance rollers 57, and a recovery unit 58. The substrate supply unit 56 stores a roll body BMr in which the substrate BM is wound in a roll shape in the longitudinal direction, and feeds out a strip of the substrate BM from the roll body BMr and sends it into the reaction chamber 51.

[0050] The plurality of conveyance rollers 57 are installed in the reaction chamber 51 and constitute a conveyance path for the substrate BM. The substrate BM sent out from the substrate supply unit 56 is introduced into a region above the solution LQ in the reaction chamber 51. The plurality of conveyance rollers 57 are installed so as to convey the substrate BM into the solution LQ, immerse it in the solution LQ, and then convey it again to a region above the solution LQ in the reaction chamber 51. Further, the conveyance roller 57 in the solution LQ is installed so that the substrate BM is arranged in a posture along the liquid surface of the solution LQ below the plasma electrode 65.

[0051] Although details will be described later, in the plasma processing apparatus 50, while being immersed in the solution LQ, the upper surface is irradiated with plasma generated by the plasma electrode 65 to form the active material layer 22. The substrate BM in which the active material layer 22 is formed and sent out of the reaction chamber 51 by the conveyance roller 57 is recovered by the recovery unit 58. The recovery unit 58 is configured to wind up and recover the substrate BM on which the active material layer 22 is formed in a roll shape.

[0052] The plasma generation unit 60 is provided above the reaction chamber 51 and generates plasma in the reaction chamber 51. The plasma generation unit 60 includes a gas supply unit 61, an exhaust unit 62, a plasma electrode 65, an electrode holding unit 66, and a plasma power supply unit 67.

[0053] The gas supply unit 61 is connected to the upper part of the reaction chamber 51 and supplies a reaction gas for generating plasma in the region above the solution LQ in the reaction chamber 51. In the present embodiment, the gas supply unit 61 supplies argon (Ar) as the reaction gas. Note that the reaction gas is not limited to argon. For example, hydrogen may be used as the reaction gas.

[0054] The gas supply unit 61 supplies the reaction gas at a flow rate of, for example, about 1 to 10 slm. The unit "slm" indicates the flow rate per minute at 1 atmosphere (atm) and 0°C.

[0055] The exhaust unit 62 is connected to the upper part of the reaction chamber 51 and discharges the gas in the region above the solution LQ in the reaction chamber 51. During the execution of the plasma treatment, the exhaust unit 62 controls the atmospheric pressure in the reaction chamber 51 to a predetermined target value. The target value of the atmospheric pressure in the reaction chamber 51 is, for example, 0.5×10 5 ~1.5×10 5 Pa or so.

[0056] The plasma electrode 65 is installed in the region above the solution LQ in the reaction chamber 51. The plasma electrode 65 is composed of, for example, a carbon base material such as a graphite sintered body. The plasma electrode 65 has a columnar shape, and its tip is installed so as to face the surface of the base material BM immersed in the solution LQ above the liquid level of the solution LQ.

[0057] The distance Da between the tip of the plasma electrode 65 and the liquid level of the solution LQ may be, for example, about 1 to 10 mm. Also, the distance Db between the tip of the plasma electrode 65 and the surface of the base material BM may be, for example, about 5 to 20 mm. The plasma electrode 65 is held by the electrode holder 66. The electrode holder 66 will be described later.

[0058] The substrate BM being conveyed and immersed in the solution LQ is grounded via the conveyance roller 57. Also, the plasma electrode 65 is connected to the plasma power supply unit 67. The plasma power supply unit 67 applies a high-frequency voltage for generating plasma between the plasma electrode 65 and the substrate BM. The voltage of the high-frequency voltage may be, for example, 5 to 15 kV, and the frequency may be 50 to 80 Hz. Note that the frequency for generating plasma is not limited to the aforementioned frequency, and may be, for example, a frequency within the range of several Hz to several hundred Hz. Also, it may be a frequency in the GHz unit corresponding to microwaves.

[0059] Referring to FIG. 5A, the electrode holder 66 in the first configuration example will be described. FIG. 5A schematically shows the electrode holder 66 and the substrate BM being conveyed in the conveyance direction MD below it when viewed from above to below. In FIG. 5A, the position of the tip of the plasma electrode 65 is shown by a dashed line, and the moving direction thereof is shown by an arrow of the dashed line.

[0060] In the plasma processing apparatus 50 of the first configuration example, the electrode holder 66 is configured as a moving mechanism capable of moving the plasma electrode 65 along the surface of the substrate BM in the width direction of the substrate BM. Thereby, since the irradiation region of the plasma on the substrate BM can be moved in the width direction of the substrate BM, it becomes possible to form the active material layer 22 over the entire width direction of the substrate BM.

[0061] In the plasma processing by the plasma processing apparatus 50 of the first configuration example, the step of scanning the plasma electrode 65 to form the active material layer 22 over the width direction of the substrate BM and the step of conveying the substrate BM in the conveyance direction MD by the substrate conveyance unit 55 are alternately repeated. Thereby, the active material layer 22 can be efficiently formed over the entire surface of the substrate BM.

[0062] Referring to FIG. 5B, the configuration of the plasma processing apparatus 50a of the second configuration example will be described. The configuration of the plasma processing apparatus 50a of the second configuration example is substantially the same as the configuration of the plasma processing apparatus 50 of the first configuration example, except that it includes a plurality of plasma electrodes 65 and the configuration of the electrode holding unit 66a is different. FIG. 5B schematically shows, as in FIG. 5A, the electrode holding unit 66a of the second configuration example and the substrate BM being conveyed in the conveyance direction MD below it when viewed from above to below.

[0063] The electrode holding unit 66a holds a plurality of plasma electrodes 65 in a state of being arranged in the width direction of the substrate BM. The plasma electrodes 65 are arranged at a predetermined interval so that the active material layer 22 can be formed without gaps in plasma processing. The plasma electrodes 65 are arranged, for example, at an interval of 1 to 50 mm. In the present embodiment, the plasma electrodes 65 are arranged at equal intervals.

[0064] In other embodiments, the plurality of plasma electrodes 65 do not have to be arranged in a row. The plurality of plasma electrodes 65 may be arranged, for example, in a staggered manner. Also, the plurality of plasma electrodes 65 do not have to be arranged parallel to the width direction of the substrate BM, and may be arranged, for example, in a direction obliquely intersecting the conveyance direction MD. The plurality of plasma electrodes 65 do not have to be arranged at equal intervals.

[0065] In the plasma processing apparatus 50a of the second configuration example, during plasma processing, each of the plurality of plasma electrodes 65 can simultaneously generate plasma between itself and the substrate BM. Therefore, the active material layer 22 can be formed at once over the arrangement direction of the plasma electrodes 65. Therefore, it is possible to shorten the formation time of the active material layer 22.

[0066] In the plasma processing by the plasma processing apparatus 50a of the second configuration example, while forming the active material layer 22 over the arrangement direction of the plasma electrodes 65 by the plurality of plasma electrodes 65, the substrate BM is conveyed in the conveyance direction MD by the substrate conveyance unit 55. Thereby, the active material layer 22 can be efficiently formed on the entire surface of the substrate BM.

[0067] Returning to FIG. 3, the process of forming the active material layer 22 on the substrate BM by plasma treatment in the plasma treatment apparatuses 50 and 50a will be described. In step P2, the substrate BM is conveyed by the substrate conveyance unit 55, and the substrate BM is immersed in the solution LQ in the reaction chamber 51.

[0068] In step P3, the plasma generation unit 60 of the plasma treatment apparatuses 50 and 50a generates plasma in the reaction chamber 51. First, the gas supply unit 61 supplies a reaction gas into the reaction chamber 51. Subsequently, by controlling the gas supply unit 61 and the exhaust unit 62, when the concentration of the reaction gas in the reaction chamber 51 reaches a predetermined concentration and pressure, the plasma power supply unit 67 applies a high-frequency voltage between the plasma electrode 65 and the substrate BM to generate discharge from the plasma electrode 65. As a result, plasma is generated from the tip of the plasma electrode 65 toward the surface of the substrate BM in the solution LQ, and as shown by the dashed line in FIG. 4, the surface of the substrate BM in the solution LQ is irradiated with plasma. In step P4, the active material layer 22 is formed on the surface of the substrate BM by the irradiation of the plasma.

[0069] Referring to FIG. 6, the mechanism by which the active material layer 22 is formed by irradiating the substrate BM with plasma will be described. FIGS. 6(a) to 6(c) schematically show the time change in the state of the solution LQ and the surface of the substrate BM in the solution LQ after the plasma treatment is started. Note that the mechanism described below is based on the considerations derived by the inventor of the present invention from the examples described later.

[0070] When plasma irradiation is started on the substrate BM in the solution LQ, as shown in Fig. 6(a), alcohols and hydrocarbons in the solution LQ are decomposed, and hydrogen atoms H and radicals RD are generated in the solution LQ. Then, as shown in Fig. 6(b), the surface of the substrate BM is eroded by the hydrogen atoms H and radicals RD, and a fine concavo-convex structure 23 is formed. During the plasma irradiation, the erosion of the surface of the substrate BM by the hydrogen atoms H and radicals RD continues, and as shown in Figs. 6(b) and 6(c), the concave and convex portions of the concavo-convex structure 23 become larger. During this period, hydrogen atoms H may enter the interior of the metal substrate 21, and minute cavities 25 may be formed inside the concavo-convex structure 23.

[0071] Also, during the formation of the concavo-convex structure 23, as shown in Fig. 6(b), carbon atoms generated in the solution LQ by the decomposition of alcohol due to plasma irradiation precipitate as particles CP of nanographene or amorphous carbon and begin to adhere to the surface of the concavo-convex structure 23 of the substrate BM. Then, as shown in Figs. 6(b) and 6(c), in parallel with the growth of the concavo-convex structure 23 on the surface of the substrate BM, particles CP of nanographene or amorphous carbon are deposited so as to cover the surface of the concavo-convex structure 23, and the active material layer 22 is formed. Minute cavities 25 may also be formed inside the active material layer 22 during this growth process.

[0072] The degree of concavity and convexity of the active material layer 22 and the deposition amount of the carbon nanostructure can be adjusted by the plasma irradiation time. The plasma irradiation time for forming the active material layer 22 may be at least 1 second or more. The plasma irradiation time may be, for example, about 1 to 60 minutes.

[0073] The active material layer 22 can be formed more efficiently in a shorter time in the region located directly below the plasma electrode 65 of the substrate BM. In the plasma processing apparatuses 50, 50a, the formation region of the active material layer 22 is expanded by alternately repeating the movement of the plasma irradiation region on the surface of the substrate BM and the plasma irradiation for a predetermined time.

[0074] Refer to FIG. 4. In the plasma processing apparatuses 50 and 50a, an active material layer 22 is formed on one surface of the base material BM by the first plasma treatment on the base material BM. In order to form the active material layer 22 on both surfaces of the base material BM, the base material BM having the active material layer 22 formed only on one side recovered by the recovery unit 58 is set as a roll body BMr in the base material supply unit 56, and the second plasma treatment is executed.

[0075] Note that during the second plasma treatment on the base material BM, the surface on the opposite side to that during the first conveyance is conveyed so as to face upward in the solution LQ. Therefore, during the first plasma treatment, it is preferable that in the recovery unit 58, the base material BM is wound so that the front and back are reversed from when it constituted the roll body BMr stored in the base material supply unit 56.

[0076] Refer to FIG. 3. In step P5, a plurality of first electrodes 20 are individually cut out from the strip-shaped base material BM having the active material layer 22 formed on both surfaces. The first electrode 20 is completed by the above steps P1 to P5.

[0077] In step P6, a second electrode 30 serving as a positive electrode is manufactured. In the subsequent step P7, as shown in FIG. 1, the first electrode 20 and the second electrode 30 are assembled in a container 11 filled with the electrolytic solution 12. The secondary battery 10 is completed by the above steps.

[0078] 1-4. Summary: As described above, the electrode 20 of the present embodiment mainly includes a carbon nanostructure composed of nanographene and amorphous carbon, and is provided with an active material layer 22 having a structure not found in the prior art, which is formed so as to cover the surface of the uneven structure 23 of the metal substrate 21. According to this electrode 20, as shown in the examples described later, the charge and discharge performance of the secondary battery 10 can be significantly improved.

[0079] Further, according to the method for manufacturing the electrode 20 and the plasma processing apparatuses 50 and 50a which are the manufacturing apparatuses for the electrode 20 of the present embodiment, the active material layer 22 can be easily formed by plasma processing together with the concavo-convex structure 23 of the metal substrate 21. Therefore, the electrode 20 can be efficiently manufactured. According to the plasma processing apparatus 50 of the first configuration example, the active material layer 22 can be formed over the entire base material BM for forming the plurality of electrodes 20 by transporting the strip-shaped base material BM and moving the plasma electrode 65 by the electrode holding unit 66. Further, according to the plasma processing apparatus 50a of the second configuration example, the active material layer 22 can be formed over the entire base material BM for forming the plurality of electrodes 20 by plasma irradiation by each of the plurality of plasma electrodes 65 and transporting the strip-shaped base material BM. Therefore, by using the plasma processing apparatuses 50 and 50a, continuous manufacturing of the plurality of electrodes 20 is possible, and the electrodes 20 can be manufactured more efficiently.

[0080] Here, for example, in the manufacturing process of a conventional secondary battery having an active material layer of carbon nanotubes, when the electrode having the active material layer formed thereon is wound into a roll for transportation, storage, etc., a part of the carbon nanotubes may be damaged or may fall off. On the other hand, according to the electrode 20 of the present embodiment, since the active material layer 22 has a thin film-like configuration, even if it is wound into a roll and transported or stored in the manufacturing process of the secondary battery 10, deterioration and dropout of the active material layer 22 are suppressed. Therefore, according to the electrode 20 of the present embodiment, since it is easy to handle, mass production of the electrode 20 becomes easy.

Example

[0081] 2. Example: 2-1. Plasma processing: Referring to FIG. 7, an example of the process of forming the active material layer 22 by the plasma treatment described in the above embodiment will be described. FIG. 7 shows captured images for each plasma irradiation time when the plasma treatment described in the above embodiment was executed under the treatment conditions shown in Table 1 below. Each captured image in FIG. 7 is an image of the surface of the base material BM of the metal substrate 21 taken from the side. The plasma irradiation time is displayed in the upper left corner of each captured image.

[0082] [Table 1]

[0083] When the plasma irradiation was started, the surface of the base material BM was flat. When 0.5 minutes had elapsed since the start of the plasma irradiation, unevenness began to be formed on the surface of the base material BM. This is presumably due to the erosion by hydrogen atoms and radicals in the solution LQ. As the plasma irradiation time further elapsed, the unevenness on the surface of the base material BM gradually became larger. When the plasma irradiation time had elapsed for 10 minutes, a plurality of minute cavities were seen in the uneven structure. During this experiment, it was confirmed that the concentrations of C atoms and O atoms increased in the vicinity of the surface of the base material BM between 1 and 10 minutes of the plasma irradiation time. This indicates that the active material layer 22 is formed while the uneven structure 23 is formed on the surface of the base material BM.

[0084] 2-2. Example of the active material layer: FIG. 8 shows a captured image of the active material layer 22 of the electrode 20 as Example E1 taken in the thickness direction of the metal substrate 21. The active material layer 22 of Example E1 was formed by the plasma treatment under the conditions shown in Table 1 above. The plasma irradiation time was 30 minutes. As shown in this captured image, in the active material layer 22 of Example E1, when viewed in the thickness direction of the metal substrate 21, a plurality of granular convex portions 24t having a width of 0.1 μm or more and 10.0 μm or less were densely distributed.

[0085] FIG. 9 shows a graph of the Raman spectrum of the active material layer 22 of Example E1. In this graph, peaks of the D band (1340 cm -1 ) and the G band (1580 cm -1 ) were observed. This result indicates that the active material layer 22 is mainly formed of a carbon nanostructure composed of nanographene or amorphous carbon.

[0086] 2-3. Comparative Examples of the Active Material Layer: FIG. 10 shows a list summarizing the photographed images of the electrodes of Comparative Examples C1, C2, and C3.

[0087] FIGS. 10(a) and 10(b) show photographed images of the surface of the electrode of Comparative Example C1, respectively. FIG. 10(a) is an image taken facing the surface of the electrode of Comparative Example C1 with a scanning electron microscope. FIG. 10(b) is an image taken at a higher magnification than the photographed image of FIG. 10(a).

[0088] The electrode of Comparative Example C1 does not have an active material layer and is composed only of a metal substrate constituting a current collector. The metal substrate of Comparative Example C1 is composed of the same copper foil as the base material BM of the metal substrate 21 of Example E1 before forming the active material layer 22. Therefore, the surface of Comparative Example C1 was composed of a flat surface as shown in the images of FIGS. 10(a) and 10(b).

[0089] FIG. 10(c) shows a photographed image of the electrode of Comparative Example C2. FIG. 10(c) is an image taken facing the surface of the active material layer of Comparative Example C2 with a scanning electron microscope. The electrode of Comparative Example C2 was configured such that a graphite active material layer was provided on the surface of a metal substrate having a flat surface similar to that of Comparative Example C1. Granular graphite constituting the active material layer is shown in FIG. 10(c).

[0090] Figures 10(d) and 10(e) show the photographed images of the electrodes of Comparative Example C3. Figure 10(d) is an image obtained by photographing the surface layer of the electrode from a direction perpendicular to the thickness direction of the electrode of Comparative Example C1 with a scanning electron microscope. Figure 10(e) is an image obtained by photographing the electrode of Comparative Example C1 facing the surface with a scanning electron microscope.

[0091] The electrode of Comparative Example C3 was configured such that carbon nanowalls were provided as an active material layer on the surface of a metal substrate having a flat surface similar to that of Comparative Example C1. In the image of Figure 10(d), the wrinkled white image, and in the image of Figure 10(e), the mesh-like white streak-like image are carbon nanowalls. The carbon nanowalls were formed in a random mesh pattern over the entire surface of the metal substrate with a substantially uniform height of about 1.0 μm by the CVD method.

[0092] 2-4. Battery performance of Examples and Comparative Examples: With reference to Figures 11 to 15, the evaluation test results of the battery performance of secondary batteries using the electrodes of the above Examples E1 and Comparative Examples C1, C2, and C3 as negative electrodes will be described.

[0093] Figure 11 shows a graph obtained from a secondary battery using the electrode of Example E1. Also, Figures 12, 13, and 14 respectively show graphs obtained from secondary batteries using the electrodes of Comparative Examples C1, C2, and C3. In Figures 11 to 14, the relationship between the voltage and the charge capacity of the secondary battery is shown by a solid-line graph during charging and a dashed-dotted line graph during discharging.

[0094] Figure 15 shows the charge capacity and specific capacity of the secondary batteries using Example E1 and Comparative Examples C2 and C3 as bar graphs, respectively. In this evaluation test, both the charging current and the discharging current were 0.5 mA.

[0095] The secondary batteries using Example E1 and Comparative Examples C1, C2, and C3 were lithium-ion secondary batteries and were fabricated with the configurations shown in Table 2 below.

[0096]

Table 2

[0097] As shown in FIGS. 11 and 15, in the secondary battery using Example E1, the charge capacity was 14.2 [mAh], and the specific capacity was 10.8 [mAh / cm 2 . In contrast, as shown in FIG. 12, in the secondary battery using the electrode composed only of the metal substrate having a flat surface of Comparative Example C1 as the negative electrode, charge and discharge could not be performed. Further, as shown in FIGS. 13 and 15, in the secondary battery using Comparative Example C2 having a graphite active material layer, the charge capacity was 4.0 [mAh], and the specific capacity was 2.0 [mAh / cm 2 . As shown in FIGS. 14 and 15, in the secondary battery using Comparative Example C3 having a carbon nanotube active material layer, the charge capacity was 12.6 [mAh], and the specific capacity was 9.4 [mAh / cm 2 .

[0098] Thus, according to the secondary battery 10 using the electrode 20 of Example E1, not only the secondary battery using the electrode of Comparative Example C1 having no active material layer, but also the secondary batteries using Comparative Examples C2 and C3 having a carbon active material layer, the battery performance was significantly improved.

[0099] As described above, according to the electrode for a power storage device according to the present invention, the battery performance of a power storage device such as a secondary battery can be significantly improved. Further, according to the manufacturing method and manufacturing apparatus of the electrode for a power storage device according to the present invention, the electrode for a power storage device can be easily manufactured.

[0100] 3. Other Embodiments: The present invention is not limited to the configurations of the above-described embodiments and examples. For example, it can also be realized in the following forms. In the following, all the configurations described as other embodiments are also positioned as one example of the forms for carrying out the present invention, similar to the above-described embodiments, the configurations described as other embodiments in the above-described embodiments, and the examples.

[0101] 3-1. Other Embodiment 1: The secondary battery using the electrode 20 of the above embodiment may be configured to involve metal ions other than lithium ions in charge and discharge. The secondary battery using the electrode 20 of the above embodiment may be configured to involve, for example, sodium (Na) ions, potassium (K) ions, magnesium (Mg) ions, etc. in charge and discharge.

[0102] 3-2. Other Embodiment 2: In the electrode 20, the active material layer 22 may be formed on at least one of the first surface 21a and the second surface 21b of the metal substrate 21. For example, it may be formed only on the first surface 21a. The electrode 20 may be applied to other power storage devices other than secondary batteries. For example, the electrode 20 may be applied to a capacitor.

[0103] 3-3. Other Embodiment 3: The plasma processing apparatuses 50, 50a do not necessarily have a configuration for continuously manufacturing a plurality of electrodes 20, and may have a configuration for manufacturing the electrodes 20 one by one. In this case, the plasma processing apparatuses 50, 50a do not necessarily have a configuration for conveying the belt-shaped base material BM by the conveying roller 57. For example, the plasma processing apparatuses 50, 50a may have a configuration for supporting the base material BM of one metal substrate 21 by a support portion installed in the solution LQ. Even with such a configuration, it is possible to manufacture the electrode 20 of the secondary battery 10 having a small size.

[0104] 3-4. Other Embodiment 4: The configuration of the plasma processing apparatus that executes the plasma processing for forming the active material layer 22 is not limited to the first configuration example and the second configuration example described in the above embodiment. The plasma processing apparatus may have, for example, a configuration in which a plurality of electrode holders 66a of the second configuration example are arranged in the conveying direction MD of the base material BM. Further, the plasma processing apparatus may include a moving mechanism that movably holds a group of a plurality of plasma electrodes 65 in a direction intersecting the conveying direction MD of the base material BM.

[0105] 3-5. Other Embodiment 5: The plasma treatment described in the above embodiment may also be applied to a method for manufacturing a power storage device other than a secondary battery. Further, the plasma treatment may be applied not only to power storage devices but also to methods for manufacturing various electrodes.

[0106] 4. Embodiment Example: The present invention can be realized in the following forms.

[0107] [First Embodiment] The first embodiment is provided as an electrode for a power storage device. The electrode for a power storage device according to the first embodiment includes a metal substrate that constitutes a current collector and has a fine concavo-convex structure formed on its surface, and a carbon nanostructure mainly composed of nanographene and amorphous carbon, which is formed so as to densely cover the surface of the concavo-convex structure, and an active material layer in which metal atoms involved in charging and discharging of the power storage device are deposited on the surface during charging of the power storage device. According to the electrode for a power storage device of the first embodiment, since a carbon nanostructure composed of nanographene and amorphous carbon is used as an active material, the battery performance of the power storage device can be enhanced. Further, since the surface of the active material layer is formed in concavo-convex shapes, the surface area of the active material layer is increased, the amount of metal deposited during charging of the power storage device can be increased, and the charging capacity of the power storage device can be enhanced. Furthermore, due to the concavo-convex structure of the active material layer, a large number of convex portions are formed on the surface of the active material layer, so that the deposition of metal on the surface of the active material layer during charging of the power storage device is promoted. Therefore, the battery performance of the power storage device can be further enhanced. In addition, since the active material layer is formed like a thin film that densely covers the surface of the metal substrate, unlike carbon nanotubes that grow so as to extend from the surface of the metal substrate, it can be suppressed from being broken or falling off in the manufacturing process of the power storage device.

[0108] [Second Embodiment] In the electrode for a power storage device according to the first embodiment, a plurality of convex portions having a width of 0.1 μm or more and 10.0 μm or less may be densely distributed on the surface of the active material layer when viewed in the thickness direction of the metal substrate. According to the electrode for the energy storage device of the second embodiment, the surface area of the active material layer can be further increased, and more convex portions can be formed on the surface of the active material layer. Therefore, the battery performance of the energy storage device can be further improved.

[0109] [Third Embodiment] In the electrode for the energy storage device of the third embodiment, the metal substrate may be made of copper or a copper alloy. If it is an electrode for the energy storage device of the third embodiment, higher battery performance can be realized in the energy storage device.

[0110] [Fourth Embodiment] The fourth embodiment is provided as a secondary battery. The secondary battery of the fourth embodiment includes a container filled with an electrolytic solution, a separator having electrical insulation and ion conductivity and partitioning the internal space of the container into a first electrode chamber and a second electrode chamber, a first electrode housed in the first electrode chamber and composed of the electrode for the energy storage device according to any one of the above embodiments, and a second electrode housed in the second electrode chamber and containing metal atoms that ionize during charging and move to the first electrode. According to the secondary battery of the fourth embodiment, the battery performance can be enhanced by the electrode for the energy storage device of the above embodiment.

[0111] [Fifth Embodiment] The fifth embodiment is provided as a method for manufacturing an electrode for an energy storage device. The manufacturing method of the fifth embodiment includes a step of immersing a base material of a metal substrate constituting a current collector in a solution of alcohols, and a step of generating plasma by applying a high-frequency voltage between a plasma electrode disposed above the solution and the base material in the solution while supplying a reaction gas for generating plasma above the solution, and a step of forming, while forming a fine concavo-convex structure on the surface of the base material by the plasma, an active material layer mainly composed of a carbon nanostructure composed of nanographene and amorphous carbon and in which metal atoms involved in charging and discharging of the energy storage device are deposited on the surface during charging of the energy storage device so as to densely cover the surface of the concavo-convex structure. According to the manufacturing method of the fifth embodiment, while forming an uneven structure on the surface of the metal substrate by plasma treatment, an active material layer of a carbon nanostructure can be formed. Therefore, an electrode for a power storage device that can improve the battery performance of the power storage device can be easily and efficiently manufactured.

[0112] [Sixth Embodiment] The manufacturing method of the sixth embodiment may further include a step of moving the plasma electrode along the surface of the base material in the solution to move the irradiation region of the plasma on the surface of the base material. According to the manufacturing method of the sixth embodiment, since the irradiation region of the plasma where the active material layer is formed on the surface of the base material can be moved, an electrode with a large area can be manufactured more efficiently.

[0113] [Seventh Embodiment] The seventh embodiment is provided as a manufacturing apparatus for an electrode for a power storage device. The manufacturing apparatus of the seventh embodiment includes a reaction chamber in which a solution of alcohols in which a base material of a metal substrate constituting a current collector is immersed is stored, and in a region above the solution in the reaction chamber, a plasma electrode disposed so as to face the surface of the base material immersed in the solution, a gas supply unit that supplies a reaction gas for generating plasma to the region above the solution in the reaction chamber, and a plasma power supply unit that applies a high-frequency voltage for generating plasma between the plasma electrode and the base material, and by the plasma generated between the plasma electrode and the base material, while forming a fine uneven structure on the surface of the base material, a carbon nanostructure composed of nanographene and amorphous carbon is used as a main component, and an active material layer in which metal atoms involved in charging and discharging of the power storage device are deposited on the surface during charging of the power storage device is formed so as to cover the surface of the uneven structure. According to the manufacturing apparatus of the seventh embodiment, while forming an uneven structure on the surface of the metal substrate by plasma treatment, an active material layer of a carbon nanostructure can be formed. Therefore, an electrode for a power storage device that can improve the battery performance of the power storage device can be easily manufactured.

[0114] [Eighth Embodiment] The manufacturing apparatus according to the seventh embodiment may further include a moving mechanism that moves the plasma electrode along the surface of the substrate in the solution. According to the manufacturing apparatus of the eighth embodiment, by moving the plasma electrode by the moving mechanism, it is possible to move the plasma irradiation region where the active material layer is formed on the surface of the substrate. Therefore, an electrode with a large electrode area can be manufactured more efficiently.

[0115] [Ninth Embodiment] The manufacturing apparatus according to the seventh embodiment or the eighth embodiment may include a plurality of the plasma electrodes arranged along the surface of the substrate, and may be configured to be able to generate plasma simultaneously between each of the plurality of plasma electrodes and the substrate. According to the manufacturing apparatus of the ninth embodiment, a wide area on the surface of the substrate can be irradiated with plasma at once by the plurality of plasma electrodes. Therefore, an electrode with a large electrode area can be manufactured more efficiently. [Description of Reference Numerals]

[0116] 10... secondary battery, 11... container, 12... electrolytic solution, 15... separator, 16... first electrode chamber, 17... second electrode chamber, 20... first electrode, 21... metal substrate, 21a... first surface, 21b... second surface, 22... active material layer, 23... concavo-convex structure, 24... surface concavo-convex structure, 24t... convex portion, 25... cavity, 30... second electrode, 31... positive electrode current collector, 31a... first surface, 31b... second surface, 32... positive electrode active material layer, 50, 50a... plasma processing apparatus, 51... reaction chamber, 52... liquid supply unit, 53... drainage unit, 55... substrate conveyance unit, 56... substrate supply unit, 57... conveyance roller, 58... recovery unit, 60... plasma generation unit, 61... gas supply unit, 62... exhaust unit, 65... plasma electrode, 66, 66a... electrode holding unit, 67... plasma power supply unit, BM... substrate, BMr... roll body, CP... particle, H... hydrogen atom, LQ... solution, MD... conveyance direction, RD... radical

Claims

1. A method for producing an electrode for an electricity storage device, comprising the steps of: A step of immersing a base material of a metal substrate constituting a current collector in an alcohol solution; A step of generating plasma by applying a high frequency voltage between a plasma electrode disposed above the solution and the substrate in the solution while supplying a reactive gas for generating plasma above the solution; forming an active material layer, which is mainly composed of a carbon nanostructure composed of nanographene and amorphous carbon and in which metal atoms involved in charging and discharging of the electricity storage device are deposited on the surface during charging of the electricity storage device, so as to densely cover the surface of the uneven structure while forming a fine uneven structure on the surface of the base material by the plasma; A manufacturing method comprising:

2. The method according to claim 1, The manufacturing method further comprises a step of moving the plasma electrode along the surface of the substrate in the solution to move a plasma irradiation area on the surface of the substrate.

3. An apparatus for manufacturing an electrode for an electricity storage device, comprising: a reaction chamber in which an alcohol solution is stored in which the base material of the metal substrate constituting the current collector is immersed; a plasma electrode disposed in a region above the solution in the reaction chamber so as to face a surface of the substrate immersed in the solution; a gas supply unit that supplies a reactive gas for generating plasma to a region above the solution in the reaction chamber; a plasma power supply unit that applies a high-frequency voltage between the plasma electrode and the substrate to generate the plasma; Equipped with The manufacturing apparatus is configured such that a fine uneven structure is formed on the surface of the substrate by plasma generated between the plasma electrode and the substrate, and an active material layer is formed so as to cover the surface of the uneven structure, the active material layer being mainly composed of a carbon nanostructure composed of nanographene and amorphous carbon, and in which metal atoms involved in the charging and discharging of the electricity storage device are precipitated on the surface when the electricity storage device is charged.

4. The manufacturing apparatus according to claim 3, further comprising: A manufacturing apparatus comprising a moving mechanism that moves the plasma electrode along the surface of the substrate in the solution.

5. The manufacturing apparatus according to claim 3 or 4, A manufacturing apparatus having a plurality of the plasma electrodes arranged along a surface of the substrate, the manufacturing apparatus being configured to be capable of simultaneously generating plasma between each of the plurality of plasma electrodes and the substrate.

Images