Capacitor electrode and method for manufacturing the same

Abstract

To provide a capacitor electrode and a manufacturing method thereof that can be charged by chemical reaction of an active material, increasing the storage capacity, and improving the energy density in addition to charge storage, and can firmly hold the sufficient amount of the active material without the need for an adhesive.SOLUTION: A capacitor electrode that can be charged by accumulating charges on the surface as a voltage is applied, a substrate 4 made of a conductive metal, a carbon film 5 made of a carbon material film formed on the surface of the substrate 4, and nanoparticles 6 made of a metal or its oxide encapsulated in a carbon film 5.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an electrode for a capacitor capable of storing charges on its surface and a method for manufacturing the same.

Background Art

[0002] An electric double layer capacitor, which is one of the energy storage devices, is capable of storing charges on the surface of the electrode and being charged. Since it does not involve a chemical reaction, it has characteristics such as rapid charging, a long cycle life, and a low risk of ignition, and is expected to be used in applications such as automobiles and mobile terminals. However, compared with a battery, such an electric double layer capacitor has a low energy density and a small storage capacity, and thus, conventionally, what is called a pseudo-capacitor or a hybrid capacitor has been proposed.

[0003] As a conventional pseudo-capacitor, for example, as disclosed in Patent Document 1, there is one in which a pseudo-capacitance metal oxide is attached to a carbon network capable of storing charges on its surface. According to such a conventional pseudo-capacitor, charges can be stored on the surface of the carbon network and it can be charged by chemically reacting the pseudo-capacitance metal oxide attached to the upper surface thereof as an active material, and the storage capacity can be increased.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above prior art, since the area for attaching the pseudo-capacitance metal oxide (active material layer) depends on the surface area of the carbon network, there is a limit to the attachment area of the pseudo-capacitance metal oxide, and there is a possibility that the pseudo-capacitance metal oxide may peel off from the surface of the carbon network. Further, in the prior art, when attaching the pseudo-capacitance metal oxide to the surface of the carbon network using an adhesive, there is also a problem that the electrical resistance during power transmission increases due to the adhesive.

[0006] The present invention has been made in view of such circumstances, and can be charged by a chemical reaction of an active material in addition to the accumulation of charges, increases the storage capacity and improves the energy density, and can firmly hold a sufficient amount of the active material while eliminating the need for an adhesive. An object of the present invention is to provide an electrode for a capacitor and a method for manufacturing the same.

Means for Solving the Problems

[0007] The invention according to claim 1 is an electrode for a capacitor that can be charged by accumulating charges on the surface upon application of a voltage, comprising a substrate made of a conductive metal, a carbon film made of a coating of a carbon material formed on the surface of the substrate, and nanoparticles made of a metal or its oxide encapsulated in the carbon film, wherein the surface of the substrate on which the carbon film is formed has a conical uneven shape 、1 μm or more Less than 5 μm protruding from the substrate with a length of Including a conical uneven shape and is characterized by this.

[0008] The invention according to claim 2 is In the capacitor electrode according to claim 1, the nanoparticles are three-dimensionally dispersed and encapsulated in the carbon film characterized by this.

[0009] The invention according to claim 3 is the electrode for a capacitor according to claim 1 or claim 2, characterized in that the carbon film has a crystalline structure or an amorphous structure.

[0010] The invention according to claim 4 is the capacitor electrode according to any one of claims 1 to 3, wherein the nanoparticles are made of a metal such as Ru, Ni, Ti, Mn, Nb, W, Mo, Ir, Ta, V, Sn, Li or Fe or an oxide thereof.

[0011] The invention according to claim 5 is the capacitor electrode according to any one of claims 1 to 4, wherein the nanoparticles are composed of particles having a diameter of 100 nm or less.

[0012] The invention according to claim 6 is applied to an electric double layer capacitor in which an electric double layer is formed on the surface of the carbon film, a pseudo-capacitor in which the nanoparticles are chemically reacted as an active material in addition to the electric double layer, or a hybrid capacitor having a positive electrode side electrode in which only an electric double layer is formed and a negative electrode in which the nanoparticles are chemically reacted as an active material in addition to the electric double layer, in the capacitor electrode according to any one of claims 1 to 5.

[0013] The invention according to claim 7 is a method for manufacturing a capacitor electrode capable of being charged by accumulating charges on the surface upon voltage application , conduction A manufacturing method in which a carbon material is formed in a film shape on the surface of a substrate made of an electrically conductive metal to form a carbon film, and nanoparticles made of a metal or an oxide thereof are encapsulated in the carbon film, wherein by irradiating the substrate with energy particles, conical irregularities having a length protruding from the substrate of 1 μm or more are formed on the surface of the substrate to cause fluffing, and at the same time, or after causing fluffing, carbon and metal are supplied to form the carbon film encapsulating the nanoparticles on the surface of the substrate where fluffing has occurred.

[0016] The invention according to claim 8 is a voltage application In a method for manufacturing a capacitor electrode capable of being charged by accumulating charges on the surface upon voltage application, Sputtering a target containing a carbon material and a metalA manufacturing method for forming a carbon film by forming a carbon material in a film shape on the surface of a substrate made of a conductive metal and encapsulating nanoparticles made of a metal or its oxide therein, wherein the surface of the substrate is irradiated with energy particles to form conical irregularities on the surface of the substrate to Fuzzing and simultaneously performing nanoparticle formation to form nanoparticles from the target and film formation Forming the carbon film encapsulated with the nanoparticles on the surface of the substrate that has been fuzzed

Figure 1

Effect of the Invention

[0017] According to the present invention, since it has a carbon film composed of a coating of a carbon material formed on the surface of a substrate and nanoparticles composed of a metal or its oxide encapsulated in the carbon film, in addition to the accumulation of charges on the surface of the carbon film, it can be charged by the chemical reaction of the nanoparticles as active materials, increasing the capacitance and improving the energy density, and can firmly hold a large amount of nanoparticles as active materials while eliminating the need for an adhesive.

Brief Description of the Drawings

[0018]

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. The capacitor electrode according to this embodiment is composed of an electrode capable of charging by accumulating charges on the surface along with voltage application and is applied to the positive electrode 2 and the negative electrode 3 of the capacitor 1 as shown in FIG. 1. Such a capacitor 1 includes a positive electrode 2 and a negative electrode 3, a case C containing an electrolytic solution Q, a separator S that divides the inside of the case C into a positive electrode side and a negative electrode side, and a power source E connected to the positive electrode 2 and the negative electrode 3.

[0020] As shown in FIGS. 1 and 2, the positive electrode 2 has a substrate 4 made of a conductive metal (Au (gold) in this embodiment), a carbon film 5, and nanoparticles 6, and is electrically connected to the power source E. When a voltage is applied to such a positive electrode 2 by the power source E, ions in the electrolytic solution Q adsorb positive charges on the surface of the carbon film 5 to form an electric double layer, thereby enabling charging (electric energy storage). application

[0021] liquid As shown in FIGS. 1 and 3, the negative electrode 3 has a substrate 4 made of a conductive metal (Au (gold) in this embodiment), a carbon film 5, and nanoparticles 6, and is electrically connected to the power source E. When a voltage is applied to such a negative electrode 3 by the power source E, ions in the electrolytic solution Q adsorb negative charges on the surface of the carbon film 5 to form an electric double layer, thereby enabling charging (electric energy storage).

[0022] ​​The carbon film 5 is composed of a film of a carbon material (C) formed on the surface of the substrate 4, and in this embodiment, it is composed of amorphous carbon including all allotropes having a molecular defect and an irregular structure. Note that the carbon film 5 may be made of a carbon material having a crystalline structure instead of amorphous carbon, or may be made of a carbon material having an amorphous structure with either a molecular defect or an irregular structure.

[0023] The nanoparticles 6 are composed of a metal or its oxide encapsulated (present) in the carbon film 5, and as shown in FIGS. 2 and 3, they are three-dimensionally dispersed and encapsulated in the carbon film 5. These nanoparticles 6 are composed of particles with a diameter of 100 nm or less, and are preferably composed of a metal such as Ru, Ni, Ti, Mn, Nb, W, Mo, Ir, Ta, V, Sn, Li, or Fe or its oxide.

[0024] Also, the nanoparticles according to this embodiment 6 function as an active material and can store electricity by undergoing a chemical reaction (electron transfer reaction and active material internal diffusion reaction between the ions in the electrolyte liquid Q and the active material). That is, according to the capacitor electrodes (positive electrode 2 and negative electrode 3) according to this embodiment, the carbon film 5 causes an electrostatic reaction to form an electric double layer, and the nanoparticles 6 in the carbon film 5 cause a chemical reaction (electron transfer reaction between the active material and the ions in the electrolyte application Q and active material internal diffusion reaction), so that the capacitance can be increased.

[0025] Next, a method for manufacturing the capacitor electrode according to this embodiment will be described. First, as shown in FIG. 8, a substrate 4 made of gold (Au) is placed on a mounting table D, and a target T is attached at an adjacent position. Such a target T is formed by forming a material plate Tb made of the material of the nanoparticles 6 at a predetermined position on a carbon material plate Ta made of a carbon material (C). In this embodiment, the material plate Tb is made of nickel (Ni).

[0026] Then, energy particles P (for example, argon ions) are irradiated onto the surface of the mounting table D at an angle of 45 degrees. In ion irradiation, a phenomenon of knocking out surface constituent elements called sputtering occurs, and the surface of the substrate 4 and the target T are sputtered. In such sputtering, since the energy particles P are irradiated onto a predetermined range of the target T including the carbon material plate Ta and the material plate Tb and the surface of the substrate 4 at an incident angle of 45 degrees, the surface of the substrate 4 is roughened, and at the same time, carbon particles from the carbon material plate Ta and the nanoparticles 6 from the material plate Tb are laminated on the substrate 4 respectively, and a carbon film 5 containing the nanoparticles 6 can be formed on the surface of the substrate 4. Note that the present invention is not limited to being manufactured by the apparatus shown in FIG. 8, and carbon and metal (oxide) may be simultaneously supplied from a film forming apparatus such as a vacuum evaporation source or an arc plasma film forming source during or after sputtering.

[0027] When the surface of the substrate 4 after sputtering is observed with a scanning electron microscope, as shown in FIG. 5, conical irregularities are densely formed, and the length of each cone is approximately 5 μm or less. Further, when observing a specific cone, regarding the part indicated by the reference sign X in FIG. 6, as shown in FIG. 7, the presence of carbon material (C) constituting the carbon film 5, gold (Au) constituting the substrate 4, and nickel (Ni) with a diameter of about 2 nm constituting the nanoparticles 6 was confirmed by measuring the interatomic distance. Note that the nanoparticles 6 may be particles of other metals or their oxides as long as the diameter is 100 nm or less (preferably about 1 to 10 nm).

[0028] Therefore, it can be seen that a carbon material (C) containing nickel (Ni) as the nanoparticles 6 is formed on the roughened surface of the substrate 4 by sputtering. Thus, in the present embodiment, by sputtering, roughening for forming conical irregularities on the surface of the substrate 4, nanoparticle formation for forming the nanoparticles 6 from the target T, and film formation for forming the carbon film 5 containing the nanoparticles 6 on the surface of the substrate 4 can be performed simultaneously.

[0029] The capacitor electrode manufactured in this way was applied to the capacitor 1 as the positive electrode 2 and the negative electrode 3 (see Fig. 1), and the voltage and current were measured by the cyclic voltammetry method for characteristic evaluation. As a result, the results shown in Fig. 4 were obtained. In this figure, those in which the nanoparticles 6 (nickel) are not encapsulated in the carbon film 5 were also measured as comparative examples, and their characteristics were displayed as graph b, while the characteristics of the examples in which the nanoparticles 6 are encapsulated in the carbon film 5 were shown as graph a and the capacitance (electric double layer capacitance) was shown as graph c.

[0030] As can be seen from such a graph, in both the examples and the comparative examples, there is a characteristic region as an electric double layer capacitor. In particular, in the examples, the storage capacitance as an electric double layer capacitor is improved compared to the comparative examples. This is considered to be due to the surface area effect of the nanoparticles 6 of 100 nm or less (1 to 2 nm in this embodiment).

[0031] Also, for the examples, after kV (for those using nickel as the nanoparticles 6 as in this embodiment, it is about 0.35 V), a typical peak due to a chemical reaction (Faraday reaction) (the site of the chemical capacitance indicated by the symbol W in Fig. 4) is seen, and it can be understood that charge storage by a chemical reaction (electron transfer reaction between the electrolyte Q and the active material and diffusion reaction within the active material) occurs. Therefore, according to the capacitor electrode according to this embodiment, by applying a voltage of a specific value kV or less with the power source E, it can be applied to an electric double layer capacitor in which an electric double layer is formed on the surface of the carbon film 5, and by applying a voltage of a specific value kV or more with the power source E, it can be applied to a pseudo-capacitor in which the nanoparticles 6 are chemically reacted as an active material in addition to the electric double layer. application Furthermore, as shown in Fig. 9, by using, for example, a positive electrode 8 made of activated carbon instead of the positive electrode 2, it can be applied to the hybrid capacitor 1'. This hybrid capacitor 1' has a positive electrode in which only an electric double layer is formed positive electrode side

[0032] 8 and a negative electrode 3, and can be used as a hybrid capacitor that combines the characteristics of an electric double layer capacitor and a pseudo-capacitor. 8 ​It has a negative electrode 3 that has [something] and causes a chemical reaction using nanoparticle 6 as an active material in addition to the electric double layer. Note that the positive electrode 8 is electrode connected to a power source E via a current collector electrode 7.

[0033] However, in this embodiment, by irradiating a target T having a carbon and nanoparticle material with energy particles P and performing sputtering, a carbon film 5 containing nanoparticle 6 is formed on the surface of the substrate 4. Any manufacturing method may be used as long as the carbon film 5 is formed by a dry method such as a physical film formation method or a surface chemical method. That is, the manufacturing method of the capacitor electrode according to this embodiment may be any method as long as a carbon material is formed in a film shape on the surface of a substrate 4 made of a conductive metal to form a carbon film 5 and nanoparticles 6 made of a metal or its oxide are encapsulated in the carbon film 5.

[0034] According to this embodiment, since it has a carbon film 5 composed of a coating of a carbon material formed on the surface of the substrate 4 and nanoparticles 6 made of a metal or its oxide encapsulated in the carbon film 5, in addition to the accumulation of charges (surface charges) on the surface of the carbon film 5, it can be charged by the chemical reaction of the nanoparticles 6 as active materials, increasing the storage capacity and improving the energy density, and can firmly hold a sufficient amount of nanoparticles 6 as active materials while eliminating the need for an adhesive.

[0035] In particular, since the nanoparticles 6 according to this embodiment are three-dimensionally dispersed and encapsulated in the carbon film 5, a larger amount of nanoparticles 6 can be dispersed and held in the carbon film 5, further increasing the storage capacity. Also, by using a carbon film 5 made of a carbon material having an amorphous structure, the chemical reaction can be more sufficiently and favorably performed using the nanoparticles 6 as active materials.

[0036] Furthermore, by sputtering, it is possible to simultaneously perform roughening to form conical irregularities on the surface of the substrate 4, nanoparticle formation to form nanoparticles 6 from the target T, and film formation to form a carbon film 5 containing the nanoparticles 6 on the surface of the substrate 4. Therefore, the manufacturing cost can be reduced, and an inexpensive capacitor electrode can be provided. Additionally, since the nanoparticles 6 are composed of particles with a diameter of 100 nm or less, they can be surely buried in the carbon film 5 and can be well encapsulated.

[0037] As described above, the present embodiment has been explained, but the present invention is not limited thereto. For example, the substrate 4 may be a conductive metal of other materials, and the nanoparticles 6 may be particles composed of other metals capable of accumulating chemical energy or their oxides. Also, the energy particles P to be irradiated are not limited to ions such as argon ions, and may be electron beams, lasers, neutral particles, or the like.

Industrial Applicability

[0038] A capacitor electrode having a substrate made of a conductive metal, a carbon film made of a carbon material coating formed on the surface of the substrate, and nanoparticles made of a metal or its oxide encapsulated in the carbon film, and a manufacturing method thereof can be applied to those having different external shapes or those with other functions added.

Explanation of Reference Numerals

[0039] 1 Capacitor 1’ Hybrid Capacitor 2 Positive Electrode Side Electrode 3 Negative Electrode Side Electrode 4 Substrate 5 Carbon Film 6 Nanoparticles 7 Positive Electrode Side Current Collector liquid 8 Positive Electrode Side Electrode E Power Supply S Separator D Mounting Table T Target Ta Carbon Material Plate Tb material plate Q electrolysis ​ C case P energy particle

Claims

1. An electrode for a capacitor that can be charged by accumulating electric charges on the surface with the application of voltage, comprising a substrate made of a conductive metal, a carbon film composed of a coating of a carbon material formed on the surface of the substrate, and nanoparticles made of a metal or its oxide encapsulated in the carbon film, and characterized in that the surface of the substrate on which the carbon film is formed has a conical uneven shape, including a conical uneven shape protruding from the substrate with a length of 1 μm or more and 5 μm or less. An electrode for a capacitor.

2. The nanoparticles are characterized by being three-dimensionally dispersed and encapsulated in the carbon film. The electrode for a capacitor according to Claim 1.

3. The carbon film is characterized by having a crystalline structure or an amorphous structure. The electrode for a capacitor according to Claim 1 or Claim 2.

4. The nanoparticles are characterized by being made of a metal or its oxide of Ru, Ni, Ti, Mn, Nb, W, Mo, Ir, Ta, V, Sn, Li, or Fe. The electrode for a capacitor according to any one of Claims 1 to 3.

5. The nanoparticles are characterized by being composed of particles with a diameter of 100 nm or less. The electrode for a capacitor according to any one of Claims 1 to 4.

6. An electric double layer capacitor in which an electric double layer is formed on the surface of the carbon film, a pseudo-capacitor in which the nanoparticles are chemically reacted as an active material in addition to the electric double layer, or a hybrid capacitor having a positive electrode side electrode on which only an electric double layer is formed and a negative electrode in which the nanoparticles are chemically reacted as an active material in addition to the electric double layer, characterized in that it is applied to the above. The electrode for a capacitor according to any one of Claims 1 to 5.

7. In a method for manufacturing an electrode for a capacitor that can be charged by accumulating charges on the surface with the application of voltage, a method of forming a carbon film by forming a carbon material in a film shape on the surface of a substrate made of a conductive metal and encapsulating nanoparticles made of a metal or its oxide in the carbon film, wherein by irradiating the substrate with energy particles, conical irregularities having a length protruding from the substrate of 1 μm or more are formed on the surface of the substrate to cause flocking, and at the same time, or after causing flocking, carbon and metal are supplied, and the carbon film encapsulating the nanoparticles is formed on the surface of the substrate on which flocking has occurred, characterized in that A method for manufacturing an electrode for a capacitor.

8. In a method for manufacturing an electrode for a capacitor that can be charged by accumulating charges on the surface with the application of voltage, a method of forming a carbon film by sputtering a target containing a carbon material and a metal to form a carbon film in a film shape on the surface of a substrate made of a conductive metal and encapsulating nanoparticles made of a metal or its oxide in the carbon film, characterized in that by irradiating the substrate with energy particles, flocking for forming conical irregularities on the surface of the substrate, nanoparticle formation for forming nanoparticles from the target, and film formation for forming the carbon film encapsulating the nanoparticles on the surface of the substrate on which flocking has occurred are performed simultaneously. A method for manufacturing an electrode for a capacitor.

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