JP7722683B2 - Metal substrate for growing carbon nanowalls, metal substrate with carbon nanowalls, and methods for manufacturing these - Google Patents

Description

The technical field of this specification relates to metal substrates for growing carbon nanowalls used in electricity storage devices, metal substrates with carbon nanowalls, and methods for manufacturing these.

Examples of chargeable and dischargeable electricity storage devices include secondary batteries and electric double-layer capacitors. Furthermore, examples of electricity storage devices that use lithium ions include lithium-ion secondary batteries, lithium-ion primary batteries, and lithium-ion capacitors.

For example, Patent Document 1 discloses a lithium-ion secondary battery having a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte. It discloses technology that uses lithium cobalt oxide or lithium nickel oxide as the positive electrode active material and carbon as the negative electrode active material (see the claims and examples of Patent Document 1). Graphite is often used as the carbon material. Graphite can absorb and release one lithium ion per six carbon atoms in a six-membered ring.

Patent No. 2668678

The inventors are currently researching and developing technology for using carbon nanowalls in the negative electrodes of lithium-ion secondary batteries. However, in order to form a film of carbon nanowalls on copper foil, which serves as the negative electrode current collector, or aluminum foil, which serves as the positive electrode current collector, it is necessary to form the film under high-temperature conditions of approximately 500°C to 600°C. In this case, when the copper foil or aluminum foil is heated before film formation, or when it is cooled after film formation, stress is generated due to the difference in thermal expansion coefficients between the copper foil or aluminum foil and the carbon nanowalls. In some cases, wrinkles occur in the negative electrode current collector or positive electrode current collector.

The problem that the technology of this specification aims to solve is to provide a metal substrate for growing carbon nanowalls, a metal substrate with carbon nanowalls, and a method for manufacturing these, which are capable of forming carbon nanowalls under low-temperature conditions of approximately 0°C or higher and lower than 500°C.

One aspect of the present invention is
a metal substrate having a first surface;
carbon nanowalls formed on the first surface of the metal substrate;
and
The metal substrate is
a plurality of protrusions on the first surface;
The area of a projected region obtained by projecting each of the protrusions onto the first surface is
10 nm ² 10000nm or more ² is as follows:
The density of the protrusions is
1 piece/μm ² More than 1000 pieces/μm ² is as follows:
The carbon nanowalls are
The protrusion is straddled.
The carbon nanowall-containing metal substrate is

This metal substrate has protrusions on its first surface. The protrusions serve as starting points for generating carbon nanowalls. In this way, the protrusions act, for example, as a catalyst. Therefore, carbon nanowalls can be formed on the metal substrate at a low temperature of 0°C or higher but lower than 500°C.

This specification provides a metal substrate for growing carbon nanowalls, a metal substrate with carbon nanowalls, and methods for manufacturing these, which are capable of forming carbon nanowalls under low-temperature conditions of approximately 0°C or higher and lower than 500°C.

1 is a schematic configuration diagram of a lithium-ion secondary battery LiB1 according to a first embodiment. 2 is a diagram schematically illustrating a cross section of a carbon nanowall CNW1 of the lithium ion secondary battery LiB1 according to the first embodiment. FIG. 1 is a diagram conceptually illustrating the structure of a carbon nanowall CNW1 of a lithium ion secondary battery LiB1 according to a first embodiment. FIG. 1 is a schematic diagram showing the configuration of a manufacturing apparatus for growing carbon nanowalls CNW1 in a lithium ion secondary battery LiB1 according to a first embodiment. FIG. 1 is a scanning electron microscope photograph (part 1) showing the surface of a copper foil after irradiating the copper foil with hydrogen radicals. 1 is a scanning electron microscope photograph showing the surface of carbon nanowalls grown at a heater set temperature of 500° C. 1 is a scanning electron microscope photograph showing a cross section of carbon nanowalls grown at a heater set temperature of 500° C. 1 is a scanning electron microscope photograph showing the surface of carbon nanowalls grown at a heater set temperature of 400° C. 1 is a scanning electron microscope photograph showing a cross section of carbon nanowalls grown at a heater set temperature of 400° C. 1 is a scanning electron microscope photograph showing the surface of carbon nanowalls grown at a heater set temperature of 300° C. 1 is a scanning electron microscope photograph showing a cross section of carbon nanowalls grown at a heater set temperature of 300° C. 1 is a scanning electron microscope photograph showing the surface of carbon nanowalls grown at a heater set temperature of 200° C. 1 is a scanning electron microscope photograph showing a cross section of carbon nanowalls grown at a heater temperature of 200° C. 1 is a scanning electron microscope photograph showing the surface of carbon nanowalls grown at a heater set temperature of 20° C. 1 is a scanning electron microscope photograph showing a cross section of carbon nanowalls grown at a heater temperature of 20° C. 1 is a scanning electron microscope photograph showing the surface of carbon nanowalls grown at a substrate temperature of 500° C. without irradiation with hydrogen radicals. 1 is a graph showing the relationship between the capacity and voltage of a lithium ion secondary battery having a negative electrode in which carbon nanowalls are grown on a copper foil at a substrate temperature of 500° C. 1 is a graph showing the relationship between the capacity and voltage of a lithium ion secondary battery having a negative electrode in which carbon nanowalls are grown on a copper foil at a substrate temperature of 400° C. 1 is a graph showing the relationship between the capacity and voltage of a lithium ion secondary battery having a negative electrode in which carbon nanowalls are grown on a copper foil at a substrate temperature of 300° C. 1 is a graph showing the relationship between the capacity and voltage of a lithium ion secondary battery having a negative electrode in which carbon nanowalls are grown on copper foil at a substrate temperature of 200° C. 1 is a graph showing the relationship between the capacity and voltage of a lithium ion secondary battery having a negative electrode in which carbon nanowalls are grown on a copper foil at a substrate temperature of 20° C. 1 is a scanning electron microscope photograph (part 2) showing the surface of a copper foil after irradiating the copper foil with hydrogen radicals. 1 is a scanning electron microscope photograph (part 3) showing the surface of a copper foil after irradiating the copper foil with hydrogen radicals. 24 is a graph showing the measurement results of the unevenness on the line in FIG. 23. 10 is a graph showing the relationship between the amount of hydrogen supplied and the number of protrusions having an area of 10 nm ² or more and 100 nm ² or less. 10 is a graph showing the relationship between the amount of hydrogen supplied and the number of protrusions having an area of 100 nm ² or more and 1000 nm ² or less. 10 is a graph showing the relationship between the amount of hydrogen supplied and the number of protrusions having an area of 1000 nm ² or more and 10000 nm ² or less. 10 is a graph showing the relationship between the amount of hydrogen supplied and the number of protrusions. 10 is a graph showing the relationship between the magnitude of the bias and the number of protrusions having an area of 10 nm ² or more and 100 nm ² or less. 10 is a graph showing the relationship between the magnitude of the bias and the number of protrusions having an area of 100 nm ² or more and 1000 nm ² or less. 10 is a graph showing the relationship between the magnitude of the bias and the number of protrusions having an area of 1000 nm ² or more and 10000 nm ² or less. 10 is a graph showing the relationship between the magnitude of bias and the number of protrusions. 1 is a photomicrograph showing the surface of a substrate when the hydrogen supply rate is 100 sccm and the bias is −25V. 34 is a micrograph showing carbon nanowalls grown on the substrate of FIG. 33. 1 is a photomicrograph showing the surface of a substrate when the hydrogen supply rate is 100 sccm and the bias is −100V. 36 is a micrograph showing carbon nanowalls grown on the substrate of FIG. 35.

Specific embodiments will be described below with reference to the drawings, taking as examples a metal substrate for growing carbon nanowalls, a metal substrate with carbon nanowalls, and a method for manufacturing these. In this specification, an energy storage device is a device that can be charged and discharged. Energy storage devices include lithium ion primary batteries, lithium ion secondary batteries, lithium ion capacitors, and other devices that use lithium ions for charging and discharging.

(First embodiment)
1 is a schematic diagram of a lithium-ion secondary battery LiB1 according to a first embodiment. The lithium-ion secondary battery LiB1 includes a positive electrode PE, a negative electrode NE, a separator Sp1, an electrolytic solution ES1, and a container V1.

The positive electrode PE is the positive electrode of the lithium-ion secondary battery LiB1. The positive electrode PE has a positive electrode current collector P1 and a positive electrode active material layer P2. The positive electrode active material layer P2 is formed on the first surface P1a and the second surface P1b of the positive electrode current collector P1.

The positive electrode current collector P1 is a metal substrate. The positive electrode current collector P1 is, for example, a metal foil. The positive electrode current collector P1 may have other shapes. The material of the positive electrode current collector P1 is, for example, Al or Ti. The material of the positive electrode current collector P1 may also be a conductor such as another metal.

The positive electrode active material layer P2 contains a positive electrode active material, a conductive additive, and a binder. The positive electrode active material layer P2 may also contain a thickener, etc. Examples of positive electrode active materials include lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, and ternary systems. Examples of conductive additives include carbon black. Examples of binders include SBR. Examples of thickeners include carboxymethyl cellulose. In this way, the positive electrode active material layer P2 contains lithium atoms.

The negative electrode NE is the negative electrode of the lithium-ion secondary battery LiB1. The negative electrode NE has a negative electrode current collector N1 and a negative electrode active material layer N2. The negative electrode active material layer N2 is formed on the first surface N1a and the second surface N1b of the negative electrode current collector N1. The negative electrode NE is a carbon nanowall body on which carbon nanowalls CNW1 are formed.

The negative electrode current collector N1 is a metal substrate for growing carbon nanowalls. The negative electrode current collector N1 is a metal substrate. The negative electrode current collector N1 is, for example, a metal foil. The negative electrode current collector N1 may have other shapes. The material of the negative electrode current collector N1 is, for example, Cu. The negative electrode current collector N1 is, for example, a copper plate or copper foil. The material of the negative electrode current collector N1 may also be a conductor such as aluminum, titanium, or other metals.

The negative electrode active material layer N2 contains a negative electrode active material. The negative electrode active material layer N2 includes carbon nanowalls CNW1 as the negative electrode active material. The carbon nanowalls CNW1 will be described later.

The separator Sp1 electrically insulates the positive electrode PE from the negative electrode NE. The separator Sp1 allows lithium ions in the electrolyte ES1 to pass through.

The electrolyte solution ES1 has the property of transferring lithium ions between the positive electrode PE and the negative electrode NE. The electrolyte solution ES1 fills the container V1. The electrolyte solution ES1 is a liquid obtained by dissolving a lithium salt such as lithium hexafluorophosphate (LiPF6) in dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or the like.

Container V1 contains a positive electrode PE, a negative electrode NE, a separator Sp1, and an electrolyte solution ES1. Container V1 is made of a material that is not easily reactive with the electrolyte solution ES1.

2. Protrusions Fig. 2 is a diagram schematically illustrating a cross section of the carbon nanowalls CNW1 of the lithium-ion secondary battery LiB1 of the first embodiment. The negative electrode current collector N1 is a metal substrate for growing the carbon nanowalls. The negative electrode current collector N1 has a first surface N1a. The first surface N1a is one surface of the negative electrode current collector N1. A plurality of protrusions PR1 are formed on the first surface N1a of the negative electrode current collector N1.

The protrusion PR1 is a portion of the negative electrode current collector N1 that partially protrudes from the first surface N1a. The protrusion PR1 may be composed of a single particle GR1, or may be composed of multiple particles GR1. In this case, the material of the particle GR1 is preferably the same as the material of the negative electrode current collector N1. The particle GR1 is preferably fused with the first surface N1a of the negative electrode current collector N1 and integrated with the negative electrode current collector N1. This is to increase the adhesion between the negative electrode current collector N1 and the particle GR1 and prevent the particle GR1 from peeling off from the negative electrode current collector N1.

The planar size of the protrusion PR1 is determined by observing the surface using a scanning electron microscope from a direction perpendicular to the first surface N1a of the negative electrode current collector N1. The area of the projection region of the protrusion PR1 projected onto the first surface N1a is 10 ^nm2 or more and 10,000 ^nm2 or less, preferably 20 nm2 or ^more and 5,000 ^nm2 or less.

The protrusions PR1 are present, for example, at a density of 10 to 10,000 per 10 μm ² of the first surface N1a of the negative electrode current collector N1. In other words, ^{the density of the projected region of the protrusions PR1 projected onto the first surface N1a is 1 to 1,000/μm 2 .} Preferably, it is 2 to 800/μm ^{2 .} More preferably, it is 3 ^{to 500/μm 2 .}

As will be described later, when protrusions PR1 are formed by irradiating hydrogen plasma, it is believed that protrusions PR1 are formed as follows: Copper particles GR1 are knocked out from the first surface N1a of the negative electrode current collector N1, and the knocked-out particles GR1 re-adhere to the first surface N1a of the negative electrode current collector N1 and fuse with the first surface N1a of the negative electrode current collector N1, thereby forming protrusions PR1. It is believed that the size and density of protrusions PR1 are important factors that determine the growth density of carbon nanowalls CNW1.

The protrusions PR1 serve as starting points for the growth of the carbon nanowalls CNW1. Therefore, the carbon nanowalls CNW1 are formed on the first surface N1a of the negative electrode current collector N1, straddling the protrusions PR1.

3. Carbon Nanowalls 3-1. Structure of Carbon Nanowalls In this specification, carbon nanowalls refer to conductive nanostructures composed primarily of carbon atoms arranged in a wall shape on a substrate such as the negative electrode current collector N1.

Figure 3 is a conceptual diagram showing the structure of the carbon nanowall CNW1 of the lithium-ion secondary battery LiB1 of the first embodiment. Figure 3 conceptually illustrates one graphene sheet GS1. The carbon nanowall CNW1 is electrically conductive. The carbon nanowall CNW1 may be composed of multiple graphene sheets GS1. The graphene sheet GS1 may not have a complete graphene structure, but may be a thin film primarily composed of carbon with a six-membered ring structure. The graphene sheet GS1 may also have a mosaic structure primarily composed of carbon with a six-membered ring structure. A mosaic structure is a structure in which multiple regions having a six-membered ring structure are discretely arranged. In other words, the carbon nanowall CNW1 does not have to be entirely single-crystal six-membered rings.

The negative electrode NE has a negative electrode current collector N1 and a negative electrode active material layer N2. The negative electrode active material layer N2 has carbon nanowalls CNW1.

The carbon nanowall CNW1 is a graphite-like material in which approximately 10 layers of graphene sheets GS1 are stacked in the thickness direction of the carbon nanowall CNW1. The number of layers may be other than the above. Because the carbon nanowall CNW1 is a graphite-like material, the carbon nanowall CNW1 has a higher electrical conductivity than carbon materials such as activated carbon.

The carbon nanowall CNW1 has a root portion R1 on the side of the negative electrode current collector N1 and a tip portion E1 on the opposite side of the negative electrode current collector N1. The root portion R1 is often a fixed portion that is fixed to the negative electrode current collector N1 via a protrusion portion PR1. The root portion R1 is also a connection portion that is electrically connected to the negative electrode current collector N1.

In the carbon nanowall CNW1, the graphene sheet GS1 is formed in a direction that intersects with the surface (first surface N1a, second surface N1b) of the negative electrode current collector N1. In FIG. 3, the graphene sheet GS1 and the negative electrode current collector N1 are approximately perpendicular. Note that the carbon nanowall CNW1 does not have to be perpendicular to the negative electrode current collector N1. Even in this case, the carbon nanowall CNW1 functions as the negative electrode NE of the lithium ion secondary battery LiB1.

As mentioned above, the carbon nanowall CNW1 is graphite made up of many stacked graphene sheets GS1. In reality, the graphene sheets GS1 do not extend completely parallel to each other. Because the graphene sheets GS1 grow in different directions at each initial growth nucleus, the graphene sheets GS1 actually merge and overlap at random (see Figure 6). As shown in Figure 3, the distance between adjacent wall-like graphite is referred to as the wall spacing D1.

The average wall spacing, which is the average value of this wall spacing D1, is related to the density of the carbon nanowalls CNW1. In other words, the wider the average wall spacing, the lower the density of the carbon nanowalls CNW1. Conversely, the narrower the average wall spacing, the higher the density of the carbon nanowalls CNW1.

3-2. Height of Carbon Nanowalls The average height H1 of the carbon nanowalls CNW1 is preferably 50 nm or more. Alternatively, the average height H1 of the carbon nanowalls CNW1 may be 200 nm or more. If the average height H1 of the carbon nanowalls CNW1 is 100 nm or more, lithium is likely to precipitate starting from the carbon nanowalls CNW1. The higher the average height H1, the longer the growth time. In other words, the higher the manufacturing cost. Therefore, for example, the average height H1 is 1 μm or more and 10 μm or less.

The average thickness W1 of the carbon nanowalls CNW1 is, for example, 0.5 nm or more and 100 nm or less. Preferably, it is 1 nm or more and 50 nm or less. More preferably, it is 1.5 nm or more and 30 nm or less.

The layer spacing of graphite is approximately 0.35 nm. Therefore, the thickness of a carbon nanowall CNW1 composed of 10 graphene sheets GS1 is approximately 3.5 nm. Although it depends on the manufacturing conditions, the average thickness of a carbon nanowall CNW1 is approximately 3.5 nm, and it is thought to be composed of 5 to 20 graphene sheets GS1. The thickness of a carbon nanowall CNW1 is, for example, 1.5 nm or more and 7 nm or less.

3-3. Wall Spacing The average wall spacing D1 between adjacent carbon nanowalls CNW1 is, for example, 10 nm or more and 500 nm or less. Preferably, it is 15 nm or more and 100 nm or less. More preferably, it is 20 nm or more and 50 nm or less. These numerical ranges are examples, and other numerical values may be used. Note that the long walls of the carbon nanowalls do not necessarily grow in parallel, and the walls may merge with each other (see Figure 6). Therefore, the spacing between the carbon nanowalls CNW1 near this merging point is narrower than the spacing between the carbon nanowalls CNW1 at other locations.

In order to grow carbon nanowalls CNW1 with a wall spacing D1 of 15 nm to 100 nm in this way, the area of the protrusions PR1, which are the starting points of the growth of the carbon nanowalls CNW1, projected onto the first surface N1a is preferably 20 ^nm2 to 5000 ^nm2 , and the density of the protrusions PR1 is preferably 3/ ^μm2 to 2500/ ^μm2 . This can be modeled as follows: To grow carbon nanowalls CNW1 with a wall spacing D1 of 20 nm, one protrusion PR1 is located at a lattice point spaced 20 nm apart, and the carbon nanowall CNW1 grows starting from the PR1 at that lattice point. In this case, assuming that the protrusions are hemispherical, a diameter of approximately 10 nm is preferable, and the area of the protrusions PR1 projected onto the first surface N1a is approximately 80 ^nm2 . Furthermore, the density of the protrusions PR1 is 2500/ ^μm2 . Similarly, to grow carbon nanowalls CNW1 with a wall spacing D1 of 50 nm, the area of the protrusions PR1 projected onto the first surface N1a is approximately 500 ^nm2 , and the density of the protrusions PR1 is ⁴⁰⁰ pieces/μm2. Furthermore, to grow carbon nanowalls CNW1 with a wall spacing D1 of 100 nm, the area of the protrusions PR1 projected onto the first surface N1a is approximately 2000 ^nm2 , and the density of the protrusions PR1 is 100 pieces/ ^μm2 . That is, in order to grow carbon nanowalls CNW1 with a wall spacing D1 of 20 nm or more and 100 nm or less, the area of the protrusions PR1, which are the starting points of the growth of the carbon nanowalls CNW1, projected onto the first surface N1a is preferably 80 nm or ^more and 2000 nm or ^less , and the density of the protrusions PR1 is preferably 100/μm or ^more and 2500/μm ^{or less} . In reality, it is not necessary for the protrusions PR1 to be present at all of the lattice points, and it is considered that the protrusions PR1 may be present at a slightly lower density.

4. Charge-Discharge Reaction Mediated by Lithium Ions 4-1. Charge-Discharge Reaction The negative electrode NE has carbon nanowalls CNW1. The carbon nanowalls CNW1 can cause two or more lithium ions per carbon atom to participate in a charge-discharge reaction during one charge or discharge.

Here, the charge/discharge reaction is, for example, a chemical reaction expressed by the following chemical reaction formula.
Li ⁺ + e ^- ⇔ Li...(1)
Li1-x CoO2 + xLi ⁺ + xe ^- ⇔ LiCoO2 …(2)
Equation (1) represents a reaction in the negative electrode active material layer N2. Equation (2) represents a reaction in the positive electrode active material layer P2. Both reactions involve lithium ions and electrons. A charge/discharge reaction is a chemical reaction in the positive electrode PE or negative electrode NE in which lithium ions are involved and electrons are exchanged. This charge/discharge reaction can result in the absorption or release of lithium ions, as well as the precipitation, deposition, adsorption, and dissolution of lithium or lithium compounds. Note that if lithium or lithium compounds are precipitated, the charge/discharge reaction can occur outside the positive electrode active material layer P2 or negative electrode active material layer N2. Note that the type of charge/discharge reaction varies depending on the materials of the positive electrode active material layer P2 and the negative electrode active material layer N2.

5. Manufacturing Apparatus A manufacturing apparatus for forming the carbon nanowalls CNW1 on the first surface N1a of the negative electrode current collector N1 will be described.

Figure 4 is a schematic diagram showing the configuration of a manufacturing apparatus 1 for growing carbon nanowalls CNW1 in a lithium-ion secondary battery LiB1 according to the first embodiment. The manufacturing apparatus 1 has a plasma generation chamber 46 and a reaction chamber 10. The plasma generation chamber 46 is used to generate plasma therein and also to generate radicals to be supplied to the reaction chamber 10. The reaction chamber 10 is used to form carbon nanowalls CNW1 using the radicals generated in the plasma generation chamber 46.

The manufacturing apparatus 1 also has a waveguide 47, a quartz window 48, and a slot antenna 49. The waveguide 47 is used to introduce microwaves 39. The slot antenna 49 is used to introduce microwaves 39 from the quartz window 48 into the plasma generation chamber 46.

The plasma generation chamber 46 is used to generate surface wave plasma (SWP) using microwaves 39. The plasma generation chamber 46 is provided with a radical source inlet 42. The radical source inlet 42 is used to supply a radical source gas into the plasma 61 generated in the plasma generation chamber 46.

A partition wall 44 is provided between the plasma generation chamber 46 and the reaction chamber 10. The partition wall 44 separates the plasma generation chamber 46 from the reaction chamber 10. The partition wall 44 also serves as the first electrode 22 for applying voltage. A through-hole 14 is formed in the partition wall 44. This is to supply radicals generated in the plasma generation chamber 46 to the reaction chamber 10.

The reaction chamber 10 is used to generate capacitively coupled plasma (CCP). It is also used to form carbon nanowalls CNW1 on the negative electrode current collector N1. The reaction chamber 10 includes a second electrode 24, a heater 25, a raw material inlet 12, and an exhaust port 16. The second electrode 24 is used to apply a voltage between the first electrode 22 and the second electrode 24. The heater 25 is used to heat the negative electrode current collector N1 and control the temperature of the negative electrode current collector N1. The raw material inlet 12 is used to supply a carbon-based gas 32, which is a raw material for the carbon nanowalls. The exhaust port 16 is connected to a vacuum pump or the like. The vacuum pump is used to adjust the pressure inside the reaction chamber 10.

As mentioned above, the partition wall 44 also serves as the first electrode 22 for applying a voltage between it and the second electrode 24. A power source and a circuit are connected to the first electrode 22. This is to control the potential of the first electrode 22 over time. The second electrode 24 is used to apply a voltage between it and the first electrode 22. The second electrode 24 also serves as a mounting base for placing the negative electrode current collector N1. The second electrode 24 is grounded. The distance between the first electrode 22 and the second electrode 24 is approximately 5 cm. Of course, this value is not limited to this value.

6. Negative Electrode Manufacturing Method 6-1. Protrusion Formation Step First, the negative electrode current collector N1 before the formation of carbon nanowalls CNW1 is placed inside the manufacturing apparatus 1. At this time, the first surface N1a of the negative electrode current collector N1 faces up, and the second surface N1b is in contact with the second electrode 24. Next, microwaves 39 are introduced into the waveguide 47. The microwaves 39 are introduced into the plasma generation chamber 46 through the quartz window 48 by the slot antenna 49. This generates high-density plasma 60.

This high-density plasma 60 then diffuses inside the plasma generation chamber 46, becoming plasma 61. This plasma 61 contains ions of the radical source supplied from the radical source inlet 42. A gas containing hydrogen gas is used as the radical source. Most of the ions in the plasma 61 are attracted to and collide with the partition wall 44. The radicals 38 in the plasma 61 pass through the through-holes 14 in the partition wall 44 without being attracted to the partition wall 44, and enter the reaction chamber 10. A voltage is then applied between the first electrode 22 and the second electrode 24. This generates plasma 34 inside the reaction chamber 10.

Radicals 38 are present in the plasma 34 atmosphere. In this plasma 34 atmosphere, protrusions PR1 grow on the first surface N1a of the negative electrode current collector N1. During this process, copper particles GR1 are scattered from the first surface N1a of the negative electrode current collector N1 and re-adhere to the first surface N1a of the negative electrode current collector N1.

The pressure inside the reaction chamber 10 is within the range of 5 to 2000 mTorr (0.65 Pa to 267 Pa). The temperature of the negative electrode current collector N1 is within the range of 0°C or higher and lower than 500°C. Preferably, it is within the range of 0°C or higher and 400°C or lower. Of course, these are merely examples, and the temperature is not limited to these numerical ranges.

6-2. Carbon Nanowall Growth Process Next, carbon nanowalls CNW1 are grown on the protrusions PR1 inside the manufacturing apparatus 1. As in the case of growing the protrusions PR1, plasma 61 is generated. In addition to radicals 38, a carbon-based gas 32 is supplied from the raw material inlet 12 into the reaction chamber 10. Hydrogen gas is used as the radical source for the radicals 38, and, for example, CH4 or C2F6 is used as the carbon-based gas 32. Of course, other gases may also be used. Furthermore, a rare gas such as Ar may be added to these gases.

In this way, a gas containing carbon atoms is converted into plasma inside the manufacturing apparatus 1 and supplied to the negative electrode current collector N1. Carbon nanowalls are grown on the protrusions PR1 on the first surface N1a of the negative electrode current collector N1, with the protrusions PR1 serving as growth starting points.

The pressure inside the reaction chamber 10 is within the range of 5 to 2000 mTorr (0.65 Pa to 267 Pa). Furthermore, the temperature of the negative electrode current collector N1 is within the range of 0°C to 500°C. Of course, these are merely examples and are not limited to these numerical ranges.

In this way, in the first embodiment, a gas containing hydrogen gas is converted into plasma and supplied to a metal substrate, and protrusions are formed on the first surface of the metal substrate by fusing multiple particles of the same material as the metal substrate with the first surface. A gas containing carbon atoms is converted into plasma and supplied to the metal substrate, and carbon nanowalls are grown on the protrusions on the first surface of the metal substrate.

8. Effects of the First Embodiment The negative electrode NE of the lithium-ion secondary battery LiB1 of the first embodiment has a protrusion PR1. The protrusion PR1 is formed by an aggregate of a plurality of particles GR1 fused to the first surface N1a of the negative electrode current collector N1. Therefore, carbon nanowalls CNW1 are easily generated starting from the protrusion PR1. Therefore, the film formation temperature of the carbon nanowalls CNW1 is 0°C or higher and 500°C or lower, which is lower than the conventional film formation temperature.

9. Modification 9-1. Amorphous Carbon Layer The negative electrode NE may have an amorphous carbon layer AC1. The amorphous carbon layer AC1 is conductive. The amorphous carbon layer AC1 is located between the first surface N1a of the negative electrode current collector N1 and the carbon nanowall CNW1. The amorphous carbon layer AC1 is a layer that can serve as a starting point for the growth of the graphene sheet GS1 that constitutes the carbon nanowall CNW1. The film thickness of the amorphous carbon layer AC1 is, for example, 10 nm or more and 300 nm or less. Preferably, it is 10 nm or more and 100 nm or less. More preferably, it is 12 nm or more and 30 nm or less.

9-2. Manufacturing Apparatus In the first embodiment, the protrusion formation process and the carbon nanowall growth process are performed consecutively inside the manufacturing apparatus 1. However, the protrusion formation process and the carbon nanowall growth process may be performed in separate apparatuses. Also, a plasma-based film formation apparatus other than the manufacturing apparatus 1 may be used.

9-3. Protrusion Forming Step Other treatments may be performed as the protrusion forming step. Examples of treatments in the protrusion forming step include pressure treatment such as pressing, chemical treatment, and sputtering using a copper or aluminum target.

9-4. Metal Substrate The metal substrate preferably contains at least one of copper and aluminum. For example, the metal substrate contains copper, a copper alloy, aluminum, or an aluminum alloy. The metal substrate may be in the form of a plate, foil, or other shape.

9-5. Combinations The above modifications may be freely combined.

(experiment)
1. Formation of protrusions Protrusions PR1 were formed on copper foil (copper substrate) inside the manufacturing apparatus 1. The conditions are shown in Table 1. The flow rate of hydrogen gas was 50 sccm. The flow rate of Ar was 5 sccm. The microwave power (MW power) was 400 W. The power applied between the electrodes (CCP power) was 400 W. The temperature of the heater 25 was 560°C. The processing time was 10 minutes.

Note that no carbon-based gas 32, which serves as the raw material gas for carbon nanowalls CNW1, is supplied to the interior of the manufacturing apparatus 1. As a result, hydrogen gas plasma is generated, and hydrogen radicals are supplied to the copper foil.

[Table 1]
Conditions Protrusion formation process H2 (sccm) 50
Ar (sccm) 5
MW power (W) 400
CCP power (W) 400
Pressure (Pa) 2
Heater temperature (℃) 560
Processing time (min) 10

Figure 5 is a scanning electron microscope photograph (part 1) showing the surface of copper foil after it has been irradiated with hydrogen radicals. Figure 5 shows that numerous copper particles have accumulated on the surface of the copper foil, forming protrusions. Judging from the shape of the particles observed, it is believed that the copper particles were knocked out of the copper foil by the irradiation of hydrogen radicals and have re-adhered to the surface of the copper foil.

2. Formation of protrusions and carbon nanowalls 2-1. Film formation Protrusions PR1 and carbon nanowalls CNW1 were formed on copper foil (copper substrate) inside the manufacturing apparatus 1. The conditions for this are shown in Table 2. When growing the protrusions PR1 and carbon nanowalls CNW1, the temperature of the heater 25 was changed between room temperature (RT) and 500°C.

[Table 2]
Conditions Protrusion formation process CNW growth process CH4 (sccm) 0 100
H2 (sccm) 50 50
Ar(sccm) 5 5
MW power (W) 400 400
CCP power (W) 400 400
Pressure (Pa) 2 1
Heater temperature (℃) 20-500 20-500
Processing time (min) 10 10

2-2. Photograph of carbon nanowalls Figure 6 is a scanning electron microscope photograph showing the surface of carbon nanowalls grown at a heater set temperature of 500°C. The substrate temperature is determined by the heater set temperature and the energy imparted to the substrate by the plasma. Although the substrate temperature may become higher than the heater set temperature due to collision of particles from the plasma with the substrate, these temperatures are estimated to be roughly the same. As shown in Figure 6, the carbon nanowalls grow randomly, with the walls merging with each other.

Figure 7 is a scanning electron microscope photograph showing the cross section of carbon nanowalls grown at a heater setting temperature of 500°C. As shown in Figure 7, carbon nanowalls 1 μm in height were formed after 10 minutes of film formation.

Figure 8 is a scanning electron microscope photograph showing the surface of carbon nanowalls grown at a heater setting temperature of 400°C. As shown in Figure 8, the carbon nanowalls grow randomly, with the walls merging with each other.

Figure 9 is a scanning electron microscope photograph showing the cross section of carbon nanowalls grown at a heater setting temperature of 400°C. As shown in Figure 9, carbon nanowalls 900 nm in height were formed after 10 minutes of film formation.

Figure 10 is a scanning electron microscope photograph showing the surface of carbon nanowalls grown at a heater setting temperature of 300°C. As shown in Figure 10, the carbon nanowalls grow randomly, with the walls merging with each other.

Figure 11 is a scanning electron microscope photograph showing the cross section of carbon nanowalls grown at a heater setting temperature of 300°C. As shown in Figure 11, carbon nanowalls with a height of 850 nm were formed after 10 minutes of film formation.

Figure 12 is a scanning electron microscope photograph showing the surface of carbon nanowalls grown at a heater setting temperature of 200°C. As shown in Figure 12, the carbon nanowalls grow randomly, with the walls merging with each other.

Figure 13 is a scanning electron microscope photograph showing the cross section of carbon nanowalls grown at a heater setting temperature of 200°C. As shown in Figure 13, carbon nanowalls with a height of 750 nm were formed after 10 minutes of film formation.

Figure 14 is a scanning electron microscope photograph showing the surface of carbon nanowalls grown at a heater setting temperature of 20°C. As shown in Figure 14, the carbon nanowalls grow randomly, with the walls merging with each other.

Figure 15 is a scanning electron microscope photograph showing the cross section of carbon nanowalls grown at a heater setting temperature of 20°C. As shown in Figure 15, carbon nanowalls with a height of 800 nm were formed after 10 minutes of film formation.

Figure 16 is a scanning electron microscope photograph showing the surface of carbon nanowalls grown at a heater set temperature of 500°C without irradiating with hydrogen radicals. In this case, protrusions PR1 are not formed. As shown in Figure 16, even without irradiating with hydrogen radicals, carbon nanowalls grow slightly. However, the density of the carbon nanowalls is sparse. Therefore, the density of these carbon nanowalls is insufficient for use in the negative electrode of a lithium-ion secondary battery.

2-3. Lithium-ion secondary battery A lithium-ion secondary battery LiB1 of the first embodiment was manufactured. The positive electrode current collector P1 was aluminum, and the positive electrode active material was lithium cobalt oxide. The negative electrode current collector N1 was copper, and the negative electrode active material was carbon nanowalls. The electrolyte was 1 M LiPF6. The positive electrode active material layer had a diameter of 1.6 cm. The negative electrode active material layer had a diameter of 1.3 cm.

The positive electrode active material layer contained lithium cobalt oxide, a conductive additive, and a binder. The conductive additive was acetylene black. The binder was PVDF. The weight ratio of lithium cobalt oxide, acetylene black, and PVDF was 100:5:3.

Figure 17 is a graph showing the relationship between capacity and voltage of a lithium-ion secondary battery having a negative electrode in which carbon nanowalls were grown on copper foil with a heater set temperature of 500°C. The horizontal axis of Figure 17 represents charge/discharge capacity. The vertical axis of Figure 17 represents voltage. The charge or discharge current was 0.5 mA. As shown in Figure 17, the discharge capacity of the lithium-ion secondary battery was 13.1 mAh.

Figure 18 is a graph showing the relationship between capacity and voltage of a lithium-ion secondary battery having a negative electrode in which carbon nanowalls were grown on copper foil with a heater set temperature of 400°C. The horizontal axis of Figure 18 represents charge/discharge capacity. The vertical axis of Figure 18 represents voltage. The charge or discharge current was 0.5 mA. As shown in Figure 18, the discharge capacity of the lithium-ion secondary battery was 13.1 mAh.

Figure 19 is a graph showing the relationship between capacity and voltage of a lithium-ion secondary battery having a negative electrode in which carbon nanowalls were grown on copper foil with a heater set temperature of 300°C. The horizontal axis of Figure 19 represents charge/discharge capacity. The vertical axis of Figure 19 represents voltage. The charge or discharge current was 0.5 mA. As shown in Figure 19, the discharge capacity of the lithium-ion secondary battery was 13.1 mAh.

Figure 20 is a graph showing the relationship between capacity and voltage of a lithium-ion secondary battery having a negative electrode in which carbon nanowalls were grown on copper foil with a heater set temperature of 200°C. The horizontal axis of Figure 20 represents charge/discharge capacity. The vertical axis of Figure 20 represents voltage. The charge or discharge current was 0.5 mA. As shown in Figure 20, the discharge capacity of the lithium-ion secondary battery was 12.8 mAh.

Figure 21 is a graph showing the relationship between capacity and voltage of a lithium-ion secondary battery having a negative electrode in which carbon nanowalls were grown on copper foil with a heater set temperature of 20°C. The horizontal axis of Figure 21 represents charge/discharge capacity. The vertical axis of Figure 21 represents voltage. The charge or discharge current was 0.5 mA. As shown in Figure 21, the discharge capacity of the lithium-ion secondary battery was 13.1 mAh.

3. Particles 3-1. Plasma Apparatus In this experiment, the protrusion formation step was carried out using an inductively coupled plasma (ICP) apparatus instead of the manufacturing apparatus 1. Table 3 shows the processing conditions in the ICP apparatus.

[Table 3]
Conditions Protrusion formation process H2 (sccm) 100
Ar(sccm) 15
ICP power (W) 1000
Pressure (Pa) 3
Heater temperature (℃) 560
Processing time (min) 10

3-2. Hydrogen Gas Supply Amount and Protrusions The amount of hydrogen gas supplied was changed to examine the number and size of protrusions. The bias applied to the second electrode 24 was 0 V.

Figure 22 is a scanning electron microscope photograph (part 2) showing the surface of copper foil after irradiating it with hydrogen radicals.

Figure 23 is a scanning electron microscope photograph (part 3) showing the surface of copper foil after irradiating it with hydrogen radicals. Figure 23 is an enlarged photograph of a portion of Figure 22. The white areas are the protrusions.

Figure 24 is a graph showing the measurement results of the unevenness on the line in Figure 23. The horizontal axis in Figure 24 is position. The vertical axis in Figure 24 is height from the reference plane. As shown in Figure 24, protrusions with a height of approximately 200 nm and a width of approximately 200 nm were observed. As can be inferred from Figure 24, the height and width of the protrusions are approximately the same.

The area of the white region in the scanning electron microscope was measured using the scanning electron microscope's functions. The area of the white region corresponds to the two-dimensional size of the protrusion.

25 is a graph showing the relationship between the amount of hydrogen supplied and the number of protrusions with an area of 10 ^nm2 or more and 100 ^nm2 or less. The horizontal axis of FIG. 25 represents the amount of hydrogen supplied (sccm). The vertical axis of FIG. 25 represents the number of protrusions per ¹⁰ μm2. When the amount of hydrogen supplied is 100 sccm, there tends to be a large number of small protrusions with an area of 10 nm2 or ^more and 100 ^nm2 or less.

Fig. 26 is a graph showing the relationship between the amount of hydrogen supplied and the number of protrusions with an area of 100 ^nm2 or more and 1000 ^nm2 or less. The horizontal axis of Fig. 26 represents the amount of hydrogen supplied (sccm). The vertical axis of Fig. 26 represents the number of protrusions per 10 ^µm2 . When the amount of hydrogen supplied is 50 sccm, there tends to be a large number of medium-sized protrusions with an area of 100 ^nm2 or more and 1000 ^nm2 or less.

Fig. 27 is a graph showing the relationship between the amount of hydrogen supplied and the number of protrusions with an area of 1000 ^nm2 or more and 10,000 ^nm2 or less. The horizontal axis of Fig. 27 represents the amount of hydrogen supplied (sccm). The vertical axis of Fig. 27 represents the number of protrusions per ¹⁰ µm2. When the amount of hydrogen supplied is 100 sccm, there tends to be a large number of large protrusions with an area of 1000 nm2 or ^more and 10,000 ^nm2 or less.

Fig. 28 is a graph showing the relationship between the amount of hydrogen supplied and the number of protrusions. The horizontal axis of Fig. 28 represents the amount of hydrogen supplied (sccm). The vertical axis of Fig. 28 represents the number of protrusions per 10 ^µm2 . When the amount of hydrogen supplied is 100 sccm, the number of protrusions tends to be large.

As such, when the hydrogen supply rate is 100 sccm, the number of protrusions tends to be high. In this case, there are many small and large protrusions.

When the hydrogen supply rate is 50 sccm, there tends to be a large number of medium-sized protrusions with an area of 100 ^nm2 or more and 1000 ^nm2 or less. At this time, the number of large and small protrusions is not so large. Therefore, in this case, the protrusions are uniform in size to a medium extent.

3-3. Bias and protrusions The hydrogen supply rate was set to 100 sccm, and the bias applied to the second electrode 24 was varied. The bias applied to the second electrode 24 was a DC bias.

Figure 29 is a graph showing the relationship between the magnitude of the bias and the number of protrusions with an area of 10 ^nm2 or more and 100 ^nm2 or less. The horizontal axis of Figure 29 is bias. The vertical axis of Figure 29 is the number of protrusions per ¹⁰ µm2. As shown in Figure 29, by applying a negative bias, the number of protrusions with an area of 10 ^nm2 or more and 100 ^nm2 or less decreases.

FIG. 30 is a graph showing the relationship between the magnitude of the bias and the number of protrusions having an area of 100 ^nm2 or more and 1000 ^nm2 or less. The horizontal axis of FIG. 30 is the bias. The vertical axis of FIG. 30 is the number of protrusions per ¹⁰ μm2. As shown in FIG. 30, when a bias of -25 V is applied, the number of protrusions having an area of 100 nm2 or ^more and 1000 ^nm2 or less is the greatest. Therefore, when forming a substrate having a large number of protrusions having an area of 100 nm2 or ^more and 1000 ^nm2 or less, it is preferable to apply a bias of about -25 V.

FIG. 31 is a graph showing the relationship between the magnitude of the bias and the number of protrusions having an area of 1000 ^nm2 or more and 10,000 ^nm2 or less. The horizontal axis of FIG. 31 represents the bias. The vertical axis of FIG. 31 represents the number of protrusions per ¹⁰ μm2. As shown in FIG. 31, when a bias of -50 V is applied, the number of protrusions having an area of 1000 nm2 ^or more and 10,000 ^nm2 or less is the greatest. Therefore, when forming a substrate having a large number of protrusions having an area of 1000 nm2 or ^more and 10,000 nm2 or ^less , it is preferable to apply a bias of about -50 V.

Figure 32 is a graph showing the relationship between the magnitude of bias and the number of protrusions. The horizontal axis of Figure 32 is bias. The vertical axis of Figure 32 is the number of protrusions per ¹⁰ μm2. When a negative bias is applied, the number of protrusions tends to decrease as the absolute value of the bias increases.

When the bias is 0 V, there tends to be a large number of small protrusions with an area of 10 nm ^{or more} and 100 nm or ^less . When the bias is -25 ^V , there tends to be a large number of ^medium -sized protrusions with an area of 100 nm ^{or more} and 1000 nm or less. When the bias is -50 V, there tends to be a large number of large protrusions with an area of 1000 nm or ^more and 10,000 nm or less. When the bias is -100 V, there tends to be a small number of protrusions, regardless of their size.

The larger the absolute value of the negative bias, the more likely hydrogen ions are to collide with the substrate. The kinetic energy of the hydrogen ions is also higher.

In this way, by selecting the amount of hydrogen supplied and the bias value, it is possible to control to some extent the size and number of protrusions formed on the substrate.

Figure 33 is a micrograph showing the surface of a substrate when the hydrogen supply rate is 100 sccm and the bias is -25 V. As shown in Figure 33, a relatively large number of protrusions are formed.

Figure 34 is a micrograph showing carbon nanowalls grown on the substrate shown in Figure 33. The carbon nanowalls have grown sufficiently and are merging with each other.

Figure 35 is a micrograph showing the surface of a substrate when the hydrogen supply rate is 100 sccm and the bias is -100 V. As shown in Figure 35, the protrusions are sparse and few in number.

Figure 36 is a micrograph showing carbon nanowalls grown on the substrate of Figure 35. The carbon nanowalls also grow sparsely, with wide spacing between the walls. In other words, the density of the carbon nanowalls is low.

Therefore, when growing carbon nanowalls, the greater the number of protrusions, the higher the density of the carbon nanowalls tends to be.

(Additional Note)
A first aspect of the present invention provides a metal substrate for growing carbon nanowalls, comprising a first surface having a plurality of protrusions on the first surface, the protrusions projected onto the first surface having an area of 10 ^nm2 or more and 10,000 ^nm2 or less, and the protrusions having a density of 1/μm2 or ^more and 1,000/μm2 or ^less .

In the second embodiment of the metal substrate for growing carbon nanowalls, the protrusions are made of the same material as the metal substrate and are fused to the first surface of the metal substrate to form an integral part of the metal substrate.

The metal substrate for growing carbon nanowalls in the third embodiment contains at least one of copper and aluminum.

A fourth aspect of the present invention provides a metal substrate with carbon nanowalls, comprising a metal substrate having a first surface and carbon nanowalls formed on the first surface of the metal substrate. The metal substrate has a plurality of protrusions on the first surface. The area of the protrusions projected onto the first surface is 10 ^nm2 or more and 10,000 ^nm2 or less. The density of the protrusions is 1/μm2 or ^more and 1,000/μm2 or ^less . The carbon nanowalls straddle the protrusions.

In the fifth embodiment of the metal substrate with carbon nanowalls, the protrusions are made of the same material as the metal substrate and are fused to the first surface of the metal substrate, becoming one with the metal substrate.

In the sixth embodiment of the metal substrate with carbon nanowalls, the metal substrate is a copper plate or copper foil.

In the seventh aspect, the metal substrate with carbon nanowalls has an amorphous carbon layer between the first surface of the metal substrate and the carbon nanowalls.

In the eighth aspect of the method for manufacturing a metal substrate for growing carbon nanowalls, a gas containing hydrogen gas is converted into plasma and supplied to the metal substrate, forming multiple protrusions made of the same material as the metal substrate on the first surface of the metal substrate.

In the ninth aspect of the method for manufacturing a metal substrate for growing carbon nanowalls, the protrusions are made of the same material as the metal substrate and are fused to the first surface of the metal substrate.

In the tenth aspect of the method for producing a metal substrate for growing carbon nanowalls, the metal substrate is a copper plate or copper foil.

In the eleventh aspect of the method for producing a metal substrate with carbon nanowalls, a gas containing carbon atoms is converted into plasma and supplied to the metal substrate for growing carbon nanowalls, and carbon nanowalls are grown using the protrusions on the first surface of the metal substrate as growth starting points.

In the twelfth aspect of the method for producing a metal substrate with carbon nanowalls, a gas containing hydrogen is converted into plasma and supplied to the metal substrate, forming multiple protrusions made of the same material as the metal substrate on the first surface of the metal substrate; a gas containing carbon atoms is converted into plasma and supplied to the metal substrate, and carbon nanowalls are grown using the protrusions on the first surface of the metal substrate as growth starting points.

In the thirteenth aspect of the method for manufacturing a metal substrate with carbon nanowalls, the protrusions are made of the same material as the metal substrate and are fused to the first surface of the metal substrate.

In the fourteenth aspect of the method for producing a metal substrate with carbon nanowalls, the metal substrate is a copper plate or copper foil.

In the fifteenth aspect of the method for producing a metal substrate with carbon nanowalls, the temperature of the metal substrate when growing the carbon nanowalls is equal to or higher than 0°C and lower than 500°C.

LiB1...lithium ion secondary battery PE...positive electrode P1...positive electrode current collector P2...positive electrode active material layer NE...negative electrode N1...negative electrode current collector N1a...first surface PR1...projection portion GR1...particle N2...negative electrode active material layer CNW1...carbon nanowall Sp1...separator ES1...electrolyte solution V1...container E1...tip portion R1...base portion GS1...graphene sheet

Claims (13)

a metal substrate having a first surface;
carbon nanowalls formed on the first surface of the metal substrate;
and
The metal substrate is
a plurality of protrusions on the first surface;
The area of a projected region obtained by projecting each of the protrusions onto the first surface is
10 nm² or ^more and 10,000 ^nm² or less,
The density of the protrusions is
1 particle/μm ² or more and 1000 particles/μm ² or less,
The carbon nanowalls are
The metal substrate with carbon nanowalls includes the carbon nanowalls straddling the protrusions. The carbon nanowall-bearing metal substrate according to claim 1 ,
The protrusion is
The material is the same as that of the metal substrate,
The metal substrate with carbon nanowalls includes carbon nanowalls fused to the first surface of the metal substrate to be integrated with the metal substrate. The carbon nanowall-bearing metal substrate according to claim 1 or 2,
The metal substrate with carbon nanowalls may be a copper plate or a copper foil. The metal substrate with carbon nanowalls according to any one of claims 1 to 3,
The metal substrate with carbon nanowalls includes an amorphous carbon layer between the first surface of the metal substrate and the carbon nanowalls. A gas containing hydrogen gas is converted into plasma to supply hydrogen radicals to the metal substrate,
forming a plurality of protrusions made of the same material as the metal substrate on a first surface of the metal substrate ;
A method for manufacturing a metal substrate , wherein each of the protrusions is composed of one or more particles . The method for manufacturing a metal substrate according to claim 5,
The protrusion is
The material is the same as that of the metal substrate,
and fusing the first surface of the metal substrate with the second surface of the metal substrate. 7. The method for producing a metal substrate according to claim 5 or 6,
The method for manufacturing a metal substrate, wherein the metal substrate is a copper plate or a copper foil. A gas containing hydrogen gas is converted into plasma to supply hydrogen radicals to the metal substrate,
forming a plurality of protrusions made of the same material as the metal substrate on a first surface of the metal substrate;
a plasma of a gas containing carbon atoms is supplied to the metal substrate, and carbon nanowalls are grown from the protrusions on the first surface of the metal substrate as growth starting points ;
In the method for producing a metal substrate with carbon nanowalls , each of the protrusions is composed of one or more particles . 9. The method for producing a metal substrate with carbon nanowalls according to claim 8,
forming the plurality of protrusions so that the area of a projected region obtained by projecting each of the protrusions onto the first surface is 10 ^nm2 or more and 10,000 nm2 or ^less , and the density of the protrusions is 1 piece/μm2 or ^more and 1,000 pieces/ ^μm2 or less;
A method for producing a metal substrate with carbon nanowalls, comprising: 10. The method for producing a metal substrate with carbon nanowalls according to claim 9,
The protrusion is
The material is the same as that of the metal substrate,
and fusing the first surface of the metal substrate with the carbon nanowalls. 11. The method for producing a metal substrate with carbon nanowalls according to claim 8, wherein:
The method for producing a metal substrate with carbon nanowalls includes the metal substrate containing at least one of copper and aluminum. The method for producing a metal substrate with carbon nanowalls according to claim 11,
The method for producing a metal substrate with carbon nanowalls, wherein the metal substrate is a copper plate or copper foil. 13. The method for producing a metal substrate with carbon nanowalls according to claim 8, wherein:
The temperature of the metal substrate during the growth of the carbon nanowalls is
The method for producing a metal substrate with carbon nanowalls includes heating at a temperature of 0°C or higher but lower than 500°C.