Carbon nanomaterials production equipment

Abstract

To provide a carbon nano material generator capable of preventing generation of dust.SOLUTION: A carbon nano material generator for forming a carbon nano material on a body to be processed includes a reaction chamber arranging the body to be processed and having supplied carbon source gas and hydrogen and a plasma generator for generating inductive coupled plasma in a reaction chamber. The reaction chamber has an opening; the plasma generator provided so as to seal the opening includes a high frequency antenna being a metal plate and arranged on the outside of the reaction chamber; and a mesh-shaped dust prevention material without deactivating radicals in the periphery and without generating dust is arranged in the inside of the reaction chamber.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an apparatus for producing carbon nanomaterials. [Background technology]

[0002] Currently, lithium ion secondary batteries are widely used as secondary batteries for driving electronic devices, electric devices, etc. Patent Document 1 discloses a lithium ion secondary battery having a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte. It is described that lithium cobalt oxide or lithium nickel oxide is used as the positive electrode active material, and carbon is used as the negative electrode active material. 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.

[0003] In order to improve the output and operating time of lithium-ion secondary batteries, it is necessary to improve the weight energy density, and it is necessary to increase the amount of lithium ions absorbed in the positive electrode active material and the negative electrode active material.

[0004] In order to increase the amount of lithium ions absorbed by the negative electrode active material, the use of carbon nanomaterials instead of graphite as the negative electrode active material is being considered and research and development is underway. Carbon nanomaterials include carbon nanowalls, carbon nanotubes, carbon nanoflakes, carbon nanoflowers, fullerenes, and diamonds.

[0005] Patent Document 2 describes the use of carbon nanowalls as a negative electrode material for lithium ion secondary batteries. It also describes that the carbon material adheres to the inner wall surface of the reaction chamber due to the formation of the carbon nanowalls, and that the carbon material is removed by washing. It also describes that the carbon nanowalls are formed by repeating the carbon nanowall growth process and the reaction chamber washing process. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 2668678 [Patent Document 2] International Publication No. 2021 / 201199 [Patent Document 3] International Publication No. 2013 / 146182 [Patent Document 4] JP 2018-186183 A Summary of the Invention [Problem to be solved by the invention]

[0007] When carbon nanowalls are formed on a negative electrode current collector by plasma CVD, dust is generated in the gas phase during film formation, and deposits form on the inner walls of the reaction chamber. These dust and deposits fall off during film formation and adhere to the carbon nanowalls, degrading the quality and uniformity of the carbon nanowalls and significantly reducing product yields.

[0008] To prevent dust from adhering to the carbon nanowalls, it is possible to repeat the steps of growing and cleaning the carbon nanowalls as in Patent Document 2, but this would increase the number of steps and take time and effort.

[0009] In addition, while it is possible to install a shield on the inner wall of the reaction chamber, there is a possibility that the shield itself may become contaminated with dust, and there is a risk that the dust may fall off the shield and onto the carbon nanowalls. Therefore, there was a need for a technology to suppress the generation of dust and other contaminants.

[0010] The present disclosure has been made in consideration of such problems, and aims to provide a carbon nanomaterial production device in which dust generation is suppressed. [Means for solving the problem]

[0011] One aspect of the present disclosure is A carbon nanomaterial production apparatus comprising: a reaction chamber in which a workpiece is placed and to which a carbon source gas and hydrogen are supplied; and a plasma generation device that generates inductively coupled plasma in the reaction chamber, the carbon nanomaterial production apparatus forming the carbon nanomaterial on the workpiece, the carbon nanomaterial production apparatus comprising: the reaction chamber has an opening; the plasma generating device is provided so as to seal the opening and has a high-frequency antenna which is a metal plate, the high-frequency antenna being disposed outside the reaction chamber; A dust prevention material having a mesh shape and made of a material that does not deactivate radicals around the reaction chamber and does not generate dust is placed inside the reaction chamber. R, The dust prevention material is a metal material containing at least one of Cu, Al, Ti, Ni, Zn, and Si; 2 O 3 , Si 3 N 4 , pBN, SiO 2 , TiO 2 , an insulating material containing one or more of borosilicate glass, or a composite material of the metal material and the insulating material; Located in a carbon nanomaterial production device. Effect of the Invention

[0012] According to the above aspect, a high-frequency antenna which is a metal plate is used as a plasma generation device, and a dust prevention material which is made of a material that does not deactivate radicals and has a mesh-like shape is placed inside the reaction chamber, so that a carbon nanomaterial generation device can be provided which suppresses dust generation in the vicinity of the dust prevention material, and allows dust generated away from the dust prevention material to adhere. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing the configuration of a carbon nanomaterial production apparatus in embodiment 1. [Diagram 2] FIG. 1 is a cross-sectional view showing a configuration of a plasma generating device. [Diagram 3] A photograph of the inside of the reaction chamber after the formation of carbon nanowalls. [Figure 4] A photograph showing the placement of metal plates inside the reaction chamber. [Diagram 5] A photograph showing the placement of metal plates inside the reaction chamber. [Figure 6]A photo of the alumina mounting location inside the reaction chamber. [Figure 7] FIG. 13 is a diagram showing the configuration of a carbon nanomaterial production apparatus in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The carbon nanomaterial generation apparatus has a reaction chamber in which the workpiece is placed and to which a carbon source gas and hydrogen are supplied, and a plasma generation device which generates inductively coupled plasma within the reaction chamber, and forms a carbon nanomaterial on the workpiece.The reaction chamber has an opening, and the plasma generation device is arranged to seal the opening and has a high-frequency antenna which is a metal plate.The high-frequency antenna is arranged outside the reaction chamber, and a dust prevention material having a mesh-like shape and made of a material that does not deactivate radicals in its surroundings and does not generate dust is arranged inside the reaction chamber.

[0015] The dust prevention material may cover at least a part of the inner wall surface of the reaction chamber. The dust prevention material may be a container disposed inside the reaction chamber and covering at least a part of the object to be treated.

[0016] The mesh size of the dust prevention material may be 0.05 to 0.09 mm.

[0017] In addition, two or more dust prevention materials having mesh openings of different sizes may be arranged in layers.

[0018] The dust-preventing material may have periodic unevenness. The surface of the dust-preventing material may be modified with an OH group. The dust-preventing material may be positively charged.

[0019] (Embodiment 1) 1. Configuration of carbon nanomaterial production device 1 1 is a diagram showing the configuration of a carbon nanomaterial generation apparatus 1 in embodiment 1. The carbon nanomaterial generation apparatus 1 has a reaction chamber 10 in which a target object is placed, a prevention wall 11, two plasma generation devices 12, a heater 14, a susceptor 15, a quartz cover 16, a gas inlet pipe 17, and a gas outlet pipe 18. The prevention wall 11, the heater 14, the susceptor 15, and the quartz cover 16 are attached inside the reaction chamber 10.

[0020] This carbon nanomaterial generating apparatus 1 is used to form carbon nanowalls. In particular, it is used to manufacture the negative electrode of a lithium ion secondary battery. The negative electrode of a lithium ion secondary battery is formed by forming carbon nanowalls on a negative electrode current collector N1. The negative electrode current collector N1 is a metal plate or metal foil such as Cu.

[0021] The reaction chamber 10 is a container having an internal space for disposing the negative electrode current collector N1, generating plasma, and forming carbon nanowalls on the negative electrode current collector N1. The reaction chamber 10 is made of, for example, stainless steel. The reaction chamber 10 is earthed.

[0022] The reaction chamber is provided with two openings 13, and a plasma generating device 12 is provided so as to seal the openings.

[0023] The prevention wall 11 is disposed near the inner wall surface of the reaction chamber 10. The prevention wall 11 does not need to be in contact with the inner wall surface. The material of the prevention wall 11 is a material that does not inactivate radicals around the prevention wall 11 and does not generate dust. Such a material will be referred to as a dust prevention material hereinafter. Not inactivating radicals means that the life of radicals can be extended to such an extent that dust or deposits are not generated. The radicals referred to here are radicals resulting from gases (carbon source gas, hydrogen gas, inert gas) introduced from the gas introduction pipe 17 into the reaction chamber 10, and radicals resulting from the carbon source gas are radicals such as C and CH3.

[0024] The dust prevention material may be, for example, a metal material such as Cu, Al, Ti, Ni, Zn, or Si, or an insulating material such as Al2O3, Si3N4, pBN, SiO2, TiO2, or borosilicate glass. It may contain a plurality of these materials, or may be a composite material of a metal and an insulating material. For example, it may be brass (Cu-Zn alloy).

[0025] By using the above-mentioned material for the prevention wall 11, it is possible to prevent dust from being generated in the gas phase near the prevention wall 11 when carbon nanowalls are formed using the carbon nanomaterial generation apparatus 1. As a result, it is possible to prevent deposits from being generated on the inner wall surface of the reaction chamber 10 near the prevention wall 11. In addition, no deposits are generated on the prevention wall 11 itself.

[0026] Conventionally, an adhesion prevention plate is provided on the inner wall surface of the reaction chamber 10 to prevent the inner wall surface from coming into contact with the atmosphere inside the furnace, thereby preventing dust from accumulating on the inner wall surface. In this case, dust accumulates on the adhesion prevention plate, and it has become necessary to frequently replace the plate. In contrast, in the first embodiment, dust is not generated around the prevention wall 11. By making the inner wall surface of the reaction chamber 10 a space where dust is not generated, dust accumulation on the inner wall surface is prevented. Furthermore, in the first embodiment, no adhesion occurs on the prevention wall 11 itself. Therefore, the prevention wall 11 does not need to be frequently replaced, the number of steps can be reduced, and maintenance is also excellent.

[0027] As described above, the prevention wall 11 can suppress the generation of dust in the vicinity thereof, and the reason why such an effect is obtained can be presumed as follows.

[0028] The inventors analyzed the yellow dust and deposits that were generated and found that they were some kind of organic matter. As a result, it is believed that the radicals were deactivated in the reaction chamber 10, the carbon source gas polymerized, and the yellow organic matter was generated. Then, as in Experiments 2 and 3 described below, when the prevention wall 11 was provided, dust was not generated near the prevention wall 11, and no deposits were generated on the prevention wall 11 itself. It is believed that the prevention wall 11 suppresses the deactivation of radicals, and thus prevents the generation of dust around the prevention wall 11. For these reasons, it is believed that the material of the prevention wall 11 should be a material that does not deactivate radicals. It is believed that stainless steel, which is the material of the reaction chamber 10, is a material that easily deactivates radicals.

[0029] In addition, the use of a plasma generating device 12 having a structure described below is also believed to be one of the reasons why dust is not generated around the prevention wall 11. When a plasma generating device 12 having a structure described below is used, the dust and deposits are yellow organic matter, and when a capacitively coupled plasma (CCP) is used, the dust and deposits are black carbonaceous matter. Therefore, it is believed that the substance of the dust and deposits is different from that in the case of CCP. This difference in the substance of the dust and deposits is believed to be one of the reasons why dust and deposits are not generated by the prevention wall 11.

[0030] The prevention wall 11 has a mesh-like shape. The mesh-like shape may be realized by periodically providing a plurality of holes, or may be realized by weaving fibrous metal.

[0031] The reason for making the prevention wall 11 mesh-like is as follows. Since the prevention wall 11 is made of the material described above, no dust is generated around the prevention wall 11. However, dust may be generated in areas away from the prevention wall 11. By making the prevention wall 11 mesh-like, such dust can be made to adhere to the prevention wall 11 efficiently. Because the prevention wall 11 is mesh-like, the gas in the reaction chamber 10 passes through the prevention wall 11, but dust particles larger than the mesh holes cannot pass through. In short, making the prevention wall 11 mesh-like allows it to function as a filter that filters out dust.

[0032] The entire prevention wall 11 does not need to be mesh-like, and only a part of it may be mesh-like, but in order to allow dust to adhere efficiently, it is preferable that the entire prevention wall 11 be mesh-like.

[0033] The size of the mesh (diameter of the circumscribed circle of the mesh) is preferably 0.05 to 0.09 mm. Since the size of dust is approximately 0.1 to 0.2 mm, if the size of the mesh is within the above range, the gas in the reaction chamber 10 can pass through smoothly while the dust can be efficiently captured. The shape of the mesh is a circle, a square, a rectangle, a rhombus, a regular hexagon, an equilateral triangle, or the like. The arrangement of the mesh is a triangular lattice, a square lattice, a honeycomb, or the like. Two or more prevention walls 11 having different sizes of holes may be arranged in a stacked manner. Dust can be more efficiently attached to the prevention walls 11.

[0034] The surface of the prevention wall 11 may be modified with an OH group. Since the carbon fine particles are terminated with a C-H bond, by modifying the surface of the prevention wall 11 with an OH group, dust can be more efficiently attached to the prevention wall 11.

[0035] Also, the prevention walls 11 may be positively charged. Since the carbon fine particles are negatively charged, dust can adhere to the prevention walls 11 more efficiently. In this case, it is better to charge the prevention walls 11 located sufficiently far from the plasma generating device 12 positively and not charge the prevention walls 11 located in other positions. This is because there is a possibility of affecting the generation of plasma. For example, it is good to charge the prevention walls 11 located 10 cm or more away from the plasma generating device 12 positively.

[0036] The thickness of the prevention wall 11 may be any thickness within a range in which the effects described below can be obtained, and is, for example, 10 μm or more. When the prevention wall 11 is made of a metal material, the prevention wall 11 may be in the form of a plate or foil. For example, the prevention wall 11 may be formed by attaching a metal foil made of Cu to the inner wall surface of the reaction chamber 10. The prevention wall 11 may also be formed by forming a metal coating by plating or the like. When the prevention wall 11 is made of an insulating material, the prevention wall 11 may also be formed by attaching a ceramic plate to the inner wall surface of the reaction chamber 10.

[0037] Periodic projections and recesses may be provided on the prevention wall 11. This makes it difficult for dust adhering to the prevention wall 11 to peel off. It is preferable that the width of the projections is 0.02 to 0.05 mm, and the interval between the projections is 0.3 to 0.5 mm. This makes it possible to effectively prevent dust from peeling off.

[0038] The prevention wall 11 does not need to cover the entire inner wall surface of the reaction chamber 10, and may cover only a part of it.

[0039] A heating device for heating the prevention wall 11 may be provided to heat the prevention wall 11 during the formation of the carbon nanowalls. By heating the prevention wall 11, the space around the prevention wall 11 where no dust is generated can be expanded. As a result, the area in which the prevention wall 11 is provided can be reduced. Also, the distance between the prevention wall 11 and the inner wall surface of the reaction chamber 10 can be expanded. When the prevention wall 11 is heated, the temperature of the prevention wall 11 is preferably set to 100° C. or higher and 400° C. or lower. Setting the temperature to 100° C. or higher has the advantage of effectively suppressing the generation of compounds that are considered to be organic substances. Setting the temperature to 400° C. or lower has the advantage of suppressing the unnecessary growth of carbon nanowalls on the prevention wall 11.

[0040] The plasma generating device 12 is attached so as to seal the opening 13 of the reaction chamber 10. A sealing member (not shown) is used to seal the opening. The plasma generating device 12 is a device that generates inductively coupled plasma (ICP) inside the reaction chamber 10 and generates radicals. The plasma generating device 12 is a low inductance antenna, and has a structure including a high-frequency antenna 100, a reinforcing material 101, and a protective plate 102.

[0041] Fig. 2 is a diagram showing the configuration of the plasma generating device 12. Fig. 2(a) is a plan view of the plasma generating device 12 seen from the high frequency antenna 100 side, and Fig. 2(b) is a cross-sectional view taken along line AA in Fig. 2(a). Note that Fig. 2(a) shows a state in which a protective plate 102, which will be described later, has been removed.

[0042] As shown in FIG. 2, the plasma generating device 12 has a structure in which a protective plate 102, a high-frequency antenna 100, and a reinforcing material 101 are laminated in this order from the reaction chamber 10 side.

[0043] The radio frequency antenna 100 is a rectangular metal plate. One end of the long side of the metal plate is connected to a radio frequency power supply via an impedance matching device (not shown), and the other end is grounded. By using such a metal plate as the radio frequency antenna 100, the impedance is reduced. The material of the radio frequency antenna 100 is a metal such as Cu or Al.

[0044] The shape of the high frequency antenna 100 is not limited to a rectangle, but may be a polygon such as a square, a circle, an ellipse, or the like.

[0045] The reinforcing material 101 is an insulating plate provided in contact with the surface of the high-frequency antenna 100 opposite to the reaction chamber 10. The reinforcing material 101 reinforces the high-frequency antenna 100 so that it can physically withstand the pressure inside the reaction chamber 10. The reinforcing material 101 is provided with a hole (not shown) for connecting the high-frequency antenna 100 to a high-frequency power source.

[0046] The protective plate 102 is an insulating plate provided in contact with the surface of the radio frequency antenna 100 facing the reaction chamber 10. The protective plate 102 prevents the radio frequency antenna 100 from coming into contact with plasma, and prevents the metal material of the radio frequency antenna 100 from being sputtered.

[0047] Insulating materials such as alumina, quartz, aluminum nitride, silicon carbide, zirconium oxide, etc. may be used for the reinforcing material 101 and the protective plate 102. The reinforcing material 101 and the protective plate 102 may be made of the same material.

[0048] In the first embodiment, two plasma generating devices 12 are provided, but one or three or more may be provided. The number of plasma generating devices 12 may be changed depending on the size of the inside of the reaction chamber 10, etc.

[0049] The heater 14 is a device that heats the negative electrode current collector N1 on the susceptor 15 and controls the temperature. The heater 14 generates heat when a voltage is applied to it. The temperature of the heater 14 is measured by a thermocouple, and the temperature of the heater 14 is controlled by controlling the applied voltage according to the temperature.

[0050] The susceptor 15 is a base on which the negative electrode current collector N1, which is the object to be processed, is placed, and conducts heat from the heater 14 to the negative electrode current collector N1. Above the susceptor 15, a plasma generating device 12 is disposed.

[0051] The quartz cover 16 protects the heater 14, supports the load of the susceptor 15, and prevents the heater 14 and the susceptor 15 from contacting each other.

[0052] The gas inlet pipe 17 is a pipe for introducing gas into the reaction chamber 10. To form carbon nanowalls, a mixed gas of a carbon source gas and hydrogen is introduced. The carbon source gas may be a hydrocarbon gas such as CH4, or a fluorocarbon gas such as C2F6. The flow rates of the carbon source gas and hydrogen are controlled to predetermined values, and a mixed gas of the carbon source gas and hydrogen is sent from the gas inlet pipe 17 into the reaction chamber 10. In addition to the carbon source gas and hydrogen, an inert gas such as argon may be mixed. By mixing an inert gas, plasma can be generated more easily.

[0053] The gas exhaust pipe 18 is a pipe that exhausts gas from inside the reaction chamber 10 to the outside. The gas exhaust pipe 18 is connected to a vacuum pump, and the amount of gas exhausted is controlled. The pressure inside the reaction chamber 10 is controlled by controlling the amount of gas introduced from the gas inlet pipe 17 and the amount of gas exhausted from the gas exhaust pipe 18.

[0054] 2. Manufacturing method of negative electrodes for lithium-ion secondary batteries Next, a method for producing a negative electrode of a lithium ion secondary battery using the carbon nanomaterial production apparatus according to the first embodiment will be described.

[0055] First, the negative electrode current collector N1, which is the object to be processed, is placed on the susceptor 15 in the reaction chamber .

[0056] Next, the negative electrode current collector N1 is heated by the heater 14, and a mixed gas of carbon source gas and hydrogen is supplied from the gas inlet pipe 17 into the reaction chamber 10. An inert gas such as a rare gas or nitrogen may be mixed. The carbon source gas is a hydrocarbon gas such as CH4, or a fluorocarbon gas such as C2F6. Then, an ICP is generated by the plasma generator 12 to generate radicals. It is preferable that the light-emitting part of the ICP does not reach the negative electrode current collector N1. If the light-emitting part reaches the negative electrode current collector N1, a lot of ion irradiation occurs, destroying the generated nanographene, making it difficult to actually generate nanographene.

[0057] The temperature of the negative electrode current collector N1 is controlled by the heater 14 to a predetermined value in the range of 100 to 800° C. The predetermined value is, for example, 500° C. The pressure inside the reaction chamber 10 is controlled to be in the range of 0.5 to 300 Pa. The pressure is controlled by controlling the amount of gas introduced and discharged.

[0058] Under the above conditions, carbon source radicals such as CH3 reach the surface of the negative electrode current collector N1, and multiple growth nuclei of nanographene are formed discretely. The growth nuclei then grow into wall-like structures to form carbon nanowalls. The shape, growth rate, and crystallinity of the carbon nanowalls can be controlled by adjusting the flow rate ratio of the carbon source gas and hydrogen. In this way, the negative electrode of a lithium-ion secondary battery is manufactured.

[0059] Here, since the prevention wall 11 is provided near the inner wall surface of the reaction chamber 10, dust is not generated around the prevention wall 11, and the generation of dust in the gas phase and the generation of deposits on the inner wall surface during the formation of carbon nanowalls are prevented. Therefore, it is possible to prevent dust in the gas phase and deposits on the inner wall surface from falling onto the carbon nanowalls and adhering to the carbon nanowalls, thereby improving the quality and uniformity of the carbon nanowalls. Furthermore, as a result of preventing the generation of dust, the number of times a cleaning process for cleaning the inside of the reaction chamber 10 can be reduced, or a cleaning process is not necessary.

[0060] Furthermore, since the prevention wall 11 is in a mesh shape, when dust generated in an area away from the prevention wall 11 is carried by the gas flow in the reaction chamber 10, the prevention wall 11 can capture the dust while the gas passes through it. Therefore, the dust in the reaction chamber 10 can be efficiently reduced.

[0061] 3. Various Experimental Results Various experimental results relating to the first embodiment will be described.

[0062] Experiment 1 Carbon nanowalls were formed on the negative electrode current collector N1 using a carbon nanomaterial generating device that does not have a protective wall 11 on the inner wall of the reaction chamber 10. Methane was used as the carbon source gas, and a mixed gas of methane, hydrogen, and argon was supplied to the reaction chamber 10. The flow rates were methane 100 sccm, hydrogen 50 sccm, and argon 5 sccm. The ICP power was 400 W, the pressure was 1 Pa, the substrate temperature was 500° C., and the treatment time was 10 minutes.

[0063] 3 is a photograph taken inside the reaction chamber 10 after the carbon nanowalls were formed. Yellow deposits were observed on the inner wall of the reaction chamber 10, and a large amount of yellow dust was generated and fell. Thus, it was found that dust is generated when carbon nanowalls are formed without providing the prevention wall 11.

[0064] Experiment 2 A barrier wall 11 was placed on the inner wall of the reaction chamber 10 of the carbon nanomaterial production device to cover the inner wall. A metal plate made of Cu was used for the barrier wall 11, and two types of metal plate were used: a flat plate and a corrugated plate. With the barrier wall 11 placed, carbon nanowalls were formed on the negative electrode current collector N1. Other growth conditions were the same as in Experiment 1.

[0065] 4 shows photographs of the location of the metal plate in reaction chamber 10 when a flat plate was used as the metal plate, including a photograph of the state in which the metal plate was placed before carbon nanowalls were formed (left side of the figure) and a photograph of the state after carbon nanowalls were formed and with the metal plate removed (right side of the figure). As shown in Figure 4, no dust was attached to the area of ​​the inner wall of reaction chamber 10 that was covered with the metal plate, whereas dust was attached to the area that was not covered with the metal plate.

[0066] FIG. 5 shows photographs of the metal plate placement location in the reaction chamber 10 when a corrugated metal plate is used, including a photograph of the state before carbon nanowall formation (left side of the figure) and a photograph of the state after carbon nanowall formation with the metal plate removed (right side of the figure). As shown in FIG. 5, the same results as in FIG. 4 were obtained. Because the metal plate is corrugated, the inner wall of the reaction chamber 10 and the metal plate are not in close contact with each other, and there are some gaps. In other words, the inner wall surface is not completely covered. Despite this, no dust was found to adhere to the area of ​​the inner wall of the reaction chamber 10 near the metal plate. On the other hand, dust was found to adhere to the area away from the metal plate. From these results, it is considered that a space that does not generate dust spreads around the metal plate, and as a result, dust did not adhere to the area of ​​the inner wall of the reaction chamber 10 near the metal plate.

[0067] 4 and 5, it was found that dust did not adhere to the inner wall surface of the reaction chamber 10 because the inner wall surface was covered with a metal plate, but dust did not occur around the metal plate because a space in which dust is not generated spreads around the metal plate. As a result, it was found that the occurrence of adhesion to the inner wall surface of the reaction chamber 10 can be prevented even if the prevention wall 11 is not in close contact with the inner wall surface of the reaction chamber 10.

[0068] Experiment 3 A barrier wall 11 was attached to the inner wall of the reaction chamber 10 of the carbon nanomaterial production device to cover the inner wall. A flat plate made of alumina was used as the barrier wall 11. With the barrier wall 11 attached, carbon nanowalls were formed on the negative electrode current collector N1. The other growth conditions were the same as in Experiment 1.

[0069] FIG. 6 is a photograph of the location where alumina was attached inside the reaction chamber 10. In FIG. 6, the white rectangles represent the alumina. As shown in FIG. 6, no deposits were found on the alumina. Meanwhile, deposits were found on the inner walls of the reaction chamber 10 that were not covered with alumina. As a result, it was found that dust generation and adhesion can be prevented by covering the inner walls of the reaction chamber 10 with a prevention wall 11 made of alumina.

[0070] (Embodiment 2) 7 is a diagram showing the configuration of a carbon nanomaterial generation apparatus 2 in embodiment 2. The carbon nanomaterial generation apparatus 2 in embodiment 2 is provided with a container 211 instead of the prevention wall 11 of the carbon nanomaterial generation apparatus in embodiment 1, and other configurations are the same as those of the carbon nanomaterial generation apparatus 1.

[0071] The container 211 is in the shape of a box with one side open. The container 211 is placed on the susceptor 15 with the open side facing the susceptor 15 and the negative electrode current collector N1 contained inside the container 211. As a result, the negative electrode current collector N1 is covered on the sides and above by the container 211. The container 211 is also provided with a through hole (not shown) so that the gas introduced into the reaction chamber 10 can reach the inside of the container 211. The position, size, and shape of the through hole may be arbitrary as long as gas can pass through.

[0072] The container 211 is made of the same material as the prevention wall 11. That is, the material does not deactivate radicals, and is a metal material such as Cu, Al, Ti, Ni, Zn, or Si, or an insulating material such as Al2O3, Si3N4, pBN, SiO2, TiO2, or borosilicate glass.

[0073] Providing such a container 211 can prevent dust and other attachments from being generated around the container 211. As a result, dust and other attachments can be prevented from being generated around the negative electrode current collector N1, and the dust and other attachments can be prevented from falling onto the carbon nanowalls.

[0074] In the carbon nanomaterial generating apparatus 2 in the second embodiment, the container 211 is box-shaped and covers the sides and the top of the negative electrode current collector N1, but it is sufficient to cover at least a part of the negative electrode current collector N1, and it may cover only the sides or the top. However, it is preferable that as much of the area as possible is covered. For example, the container 211 may be cylindrical or rectangular tubular with both ends open, and the container 211 may be placed on the susceptor 15 so that the negative electrode current collector N1 fits inside the tube, thereby covering the sides of the negative electrode current collector N1 but not covering the top.

[0075] In addition, the container 211 is made mesh-shaped. By making the container 211 mesh-shaped, the negative electrode current collector N1 can be covered without impeding the flow of gas in the reaction chamber 10, and the arrival of the carbon source gas to the negative electrode current collector N1 is less affected. In addition, even if the container 211 is made mesh-shaped, the effect of not generating dust around it is not impaired. In addition, since the container 211 is mesh-shaped, when dust generated in an area away from the container 211 is carried by the gas flow in the reaction chamber 10, the container 211 can capture the dust while passing the gas. Therefore, the dust in the reaction chamber 10 can be efficiently reduced. In particular, it is possible to prevent dust from entering the space in the container 211. In addition, the container 211 may also be heated in the same manner as the prevention wall 11 in the first embodiment.

[0076] (Various variations) In the first embodiment, the prevention wall 11 and in the second embodiment, the container 211 are provided to prevent dust and deposits from being generated around the prevention wall 11 and the container 211, but it is of course possible to provide both the prevention wall 11 and the container 211.

[0077] In the first and second embodiments, the carbon nanomaterial generating apparatus is used to produce the negative electrode of a lithium ion secondary battery, but it can be used not only to produce the negative electrode but also to produce carbon nanowalls for other purposes. It can also be applied to produce carbon nanomaterials other than carbon nanowalls. For example, it can be applied to produce carbon nanotubes, graphene, carbon nanoflakes, carbon nanoflowers, carbon nanohorns, nanodiamonds, and fullerenes. [Explanation of symbols]

[0078] 1, 2: Carbon nanomaterial generation device 10: Reaction chamber 11: Prevention wall 12: Plasma generating device 14: Heater 15: Susceptor 16;Quartz cover 17: Gas inlet pipe 18: Gas exhaust pipe 211: Container

Claims

1. A carbon nanomaterial production apparatus comprising: a reaction chamber in which a workpiece is placed and to which a carbon source gas and hydrogen are supplied; and a plasma generation device that generates inductively coupled plasma in the reaction chamber, the carbon nanomaterial production apparatus forming the carbon nanomaterial on the workpiece, the carbon nanomaterial production apparatus comprising: the reaction chamber has an opening; the plasma generating device is provided so as to seal the opening and has a high-frequency antenna which is a metal plate, the high-frequency antenna being disposed outside the reaction chamber, a dust prevention material having a mesh shape and made of a material that does not deactivate radicals around the reaction chamber and does not generate dust is disposed inside the reaction chamber; A carbon nanomaterial generating apparatus, wherein the dust prevention material is a metal material containing one or more of Cu, Al, Ti, Ni, Zn, and Si, an insulating material containing one or more of Al2O3, Si3N4, pBN, SiO2, TiO2, and borosilicate glass, or a composite of the metal material and the insulating material.

2. The carbon nanomaterial generating apparatus according to claim 1 , wherein the dust prevention material covers at least a part of an inner wall surface of the reaction chamber.

3. 2. The carbon nanomaterial generating apparatus according to claim 1, wherein the dust prevention material is a container disposed inside the reaction chamber and covering at least a portion of the object to be processed.

4. 4. The carbon nanomaterial generating apparatus according to claim 1, wherein the mesh size of the dust prevention material is 0.05 to 0.09 mm.

5. 4. The carbon nanomaterial generating apparatus according to claim 1, wherein two or more of the dust prevention materials having different mesh sizes are arranged in a layered manner.

6. The carbon nanomaterial generating apparatus according to claim 1 , wherein the dust prevention material has periodic unevenness.

7. 4. The carbon nanomaterial generating apparatus according to claim 1, wherein the surface of the dust prevention material is modified with an OH group.

8. 4. The carbon nanomaterial generating apparatus according to claim 1, wherein the dust prevention material is positively charged.

Images