Conductive film, method for manufacturing conductive film, electrode, battery, capacitor, and dielectric elastomer transducer

Abstract

To provide a conductive film, a method for manufacturing the conductive film, an electrode, and a battery, capacitor, and dielectric elastomer transducer using the same, which make it possible to improve conductivity and flexibility.SOLUTION: The conductive film comprises a conductive polymer and carbon nanotubes disposed in a distributed manner in the conductive polymer, and is stretchable by elastic deformation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a conductive film, a method for manufacturing a conductive film, an electrode, a battery, a capacitor, and a dielectric elastomer transducer. [Background technology]

[0002] Conductive polymers are widely used as conductors in various devices and equipment. Patent Document 1 discloses an example of a conventional conductive polymer. The conductive polymer disclosed in this document is intended to be used in the solid electrolyte layer of a solid capacitor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-114604 Summary of the Invention [Problem to be solved by the invention]

[0004] In various devices and equipment, portions where conductors are used may be required to have flexibility and resistance to breakage in addition to good conductivity.

[0005] The present invention was conceived in light of the above circumstances, and its object is to provide a conductive film that can improve conductivity and flexibility, a method for manufacturing a conductive film, an electrode, and a battery, a capacitor, and a dielectric elastomer transducer that use these. [Means for solving the problem]

[0006] A conductive film provided by a first aspect of the present invention comprises a conductive polymer and carbon nanotubes dispersed in the conductive polymer, and is stretchable by elastic deformation.

[0007] In a preferred embodiment of the present invention, the stretch rate is 1% to 100% when the length in the natural state is taken as 100%.

[0008] A second aspect of the present invention provides a method for producing a conductive film, which comprises a conductive polymer and carbon nanotubes dispersed in the conductive polymer, and is stretchable, and includes a step of dispersing the carbon nanotubes in a conductive polymer solution.

[0009] The electrode provided by the third aspect of the present invention is formed using the conductive film provided by the first aspect of the present invention.

[0010] A battery provided by a fourth aspect of the present invention comprises an electrode provided by the third aspect of the present invention.

[0011] A capacitor provided by a fifth aspect of the present invention comprises an electrode provided by the third aspect of the present invention.

[0012] A sixth aspect of the present invention provides a dielectric elastomer transducer comprising an electrode provided by the third aspect of the present invention. [Effects of the Invention]

[0013] According to the present invention, it is possible to improve the conductivity and flexibility.

[0014] Other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a flowchart illustrating an example of a method for manufacturing a conductive film according to the present invention. [Figure 2] 1 is a cross-sectional perspective view showing an example of a battery according to the present invention. [Figure 3] 1 is a cross-sectional perspective view showing an example of a capacitor according to the present invention. [Figure 4] 1A and 1B are a perspective view and an enlarged cross-sectional view of a main portion showing an example of a dielectric elastomer transducer according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Preferred embodiments of the present invention will now be described in detail with reference to the drawings.

[0017] 1 is a flowchart showing an example of a method for producing a conductive film according to the present invention, which comprises a pulverized carbon particle producing step, a mixing step, and an electrode producing step.

[0018] (Pulverized carbon particle generation process) The process for producing pulverized carbon particles includes pretreatment, pulverization, and extraction.

[0019] (Pretreatment) First, single-walled carbon nanotubes (hereinafter referred to as SWCNTs, for example, SG101 manufactured by Zeon Corporation) were mixed and dispersed in a solvent so that the content was 0.35 wt %. MEK (methyl ethyl ketone) was used as the solvent. This solution was dispersed using a high-pressure homogenizer to obtain an SWCNT dispersion (first dispersion). Next, this SWCNT dispersion was left at a liquid temperature of 20 to 40°C to remove the solvent. Thereafter, the mixture was stirred using a glass stirring rod or the like until it became powdery. Note that the carbon material used in the present invention is not limited to SWCNTs, and may be, for example, double-walled nanotubes, multi-walled nanotubes, or the like.

[0020] (Crushing process) The powdered SWCNTs were pulverized using a planetary ball mill. A solvent was added to the pulverized SWCNT powder, and the mixture was dispersed again using a high-pressure homogenizer. The solvent used was CyH (cyclohexane). The SWCNT content was 0.07 to 0.15 wt%. The redispersed SWCNT dispersion (second dispersion) was transferred to a glass container and subjected to ultrasonic vibration. The mixture was then left for 24 hours to confirm that the SWCNTs had not separated from the solvent. If separation was observed, ultrasonic vibration was applied again.

[0021] (Extraction process) After confirming that no separation of the SWCNTs from the solvent was observed, ultrasonic vibrations were further applied. After leaving the mixture for approximately 30 minutes, the upper part of the SWCNT dispersion near the liquid surface was sucked up with a dropper or similar and extracted into a separate container. This yielded a pulverized carbon particle dispersion containing pulverized SWCNTs (carbon nanotubes).

[0022] (Mixing process) Next, the pulverized carbon particle dispersion produced in the pulverized carbon particle production step is mixed with a conductive polymer. Various mixing steps are performed depending on the state of the conductive polymer used in this step.

[0023] (When the conductive polymer is in solution) First, the solvent for the conductive polymer solution and the solution contained in the extracted pulverized carbon particle dispersion are selected to be the same or to be mutually miscible.

[0024] Next, a conductive polymer solution is added to the pulverized carbon particle dispersion. The amount of conductive polymer solution added is an amount that can form a conductive polymer that can expand and contract due to elastic deformation, and varies depending on the amount of conductive polymer blended and the physical properties of the conductive polymer. These are mixed in appropriate amounts and then mixed using a stirrer. Preferably, a redispersion process may be performed on these mixed solutions after the mixing process. Preferably, a redispersion process is performed using a high-pressure homogenizer. This can reduce unintended damage to the shape of the pulverized carbon particles containing SWCNTs (carbon nanotubes).

[0025] (When the conductive polymer is not in solution) The conductive polymer is not in a solution state when it is in a film state or a solid state, for example.

[0026] First, the conductive polymer is pulverized using a planetary ball mill. Next, a solvent is added to the pulverized conductive polymer, and a dispersion process is performed using a rotary homogenizer. Next, this dispersion is subjected to a second dispersion process using a high-pressure homogenizer. The solvent used here is preferably one that can dissolve the conductive polymer, even to a small extent. Furthermore, a pretreatment may be performed to improve the affinity of the conductive polymer for the solvent.

[0027] After confirming that no separation of the conductive polymer and the solvent is observed, ultrasonic vibrations may be further applied. After that, the mixture is left for about 30 minutes, and the upper part of the conductive polymer dispersion liquid near the liquid surface is sucked up with a dropper or the like and extracted into a separate container. This extracts the conductive polymer dispersion liquid. Note that this extraction process after leaving the mixture may be omitted.

[0028] The subsequent mixing of the conductive polymer dispersion and the pulverized carbon particle dispersion is performed in the same manner as in the case where the conductive polymer is in a solution state, for example. After the mixing step, the mixed solution may be subjected to the re-dispersion step described above.

[0029] (Electrode generation process) In the electrode production step, the pulverized carbon particles derived from carbon nanotubes obtained in the pulverized carbon particle production step are used to produce an electrode. This electrode is made of a conductive film in which the pulverized carbon particles derived from carbon nanotubes are impregnated in a conductive polymer.

[0030] In the electrode production step, an electrode is produced, for example, by applying the conductive dispersion obtained in the mixing step of the pulverized carbon particle dispersion and the conductive polymer dispersion. Examples of application methods include a spray method using a spray or airbrush, a roll method using a roller to apply the dispersion (including methods using an applicator or bar coater), a spin coating method in which the dispersion is spread using centrifugal force, and a dip method in which the object to be coated is immersed in the conductive dispersion. Preferably, the conductive dispersion is applied using a spray method using a spray or airbrush, and then dried to produce an electrode.

[0031] The conductive polymer for forming the conductive film of the present invention is not limited in any way. Specific examples of the conductive polymer include polypyrrole, PEDOT / PSS (dryre-dispersible pellets) Orgacon DRY manufactured by Aldrich Chemical Industries, Ltd., polyaniline (emeraldine salt) long chain / lignin graft type, SELFTRON (registered trademark) manufactured by Tosoh Corporation, SAS-F manufactured by Shin-Etsu Polymer Co., Ltd., ED-0130-M manufactured by Soken Chemical & Engineering Co., Ltd., ED-BF4 manufactured by Soken Chemical & Engineering Co., Ltd., AN-SO3-T manufactured by Soken Chemical & Engineering Co., Ltd., Aedotron (registered trademark) manufactured by Aldrich Chemical Industries, Ltd., and Oligotron (registered trademark) manufactured by Aldrich Chemical Industries, Ltd.

[0032] <Battery B1> FIG. 2 shows an example of the use of the conductive film A1. The battery B1 shown in the figure is, for example, a lithium-ion battery, and includes a positive electrode case 51, a negative electrode terminal 52, an electrode 53, an electrode 54, and a separator 55. However, the specific configuration of the battery according to the present invention is not limited in any way. The conductive film A1 is elastically stretchable. In the present invention, "elastically stretchable" does not necessarily mean that the conductive film A1 is stretched by an external force or the like and then returns to its original size when the external force is removed. This concept also includes a configuration in which the conductive film A1 is stretched by an external force or the like and then shrinks to a state slightly larger than its original size when the external force is removed. The specific configuration of the battery B1 is not limited in any way and includes various specific configurations, such as lithium-ion batteries containing a liquid inside, as well as all-solid-state batteries.

[0033] The positive electrode case 51 is a case made of metal such as aluminum, and also serves as a positive electrode terminal. The positive electrode case 51 is electrically connected to an electrode 53 serving as a positive electrode plate. The negative electrode terminal 52 is electrically connected to an electrode 54 serving as a negative electrode plate. The electrodes 53 and 54 are alternately stacked. A separator 55 is provided between the electrodes 53 and 54. In the illustrated example, the electrodes 53 and 54 and the separator 55 are wound into a cylindrical shape.

[0034] Next, the functions of the conductive film A1, the electrodes 53 and 54, and the battery B1 will be described.

[0035] The resistance of the conductive polymer used as the material for the conductive film A1 was approximately 550 Ω, while the resistance of the conductive film A1 was reduced to approximately 15 Ω. Furthermore, the conductive film A1 had sufficient flexibility, with an expansion rate of 25% when the natural length was 100%. This makes it possible to improve conductivity compared to when a single conductive polymer is used. It also makes it possible to improve flexibility compared to when a good conductor similar to the conductive film A1 is used.

[0036] The electrodes 53, 54 made of the conductive film A1 have excellent conductivity and flexibility. Therefore, when the battery B1 is used, for example, and an external impact is applied to the battery B1, it is possible to prevent the electrodes 53, 54 from being damaged. Furthermore, even if the electrodes 53, 54 are deformed by an impact, they are expected to maintain good conductivity. Furthermore, the electrodes 53, 54 made of the conductive film A1 have the advantage of being less susceptible to corrosion than electrodes made of metals, etc.

[0037] 3 and 4 show another embodiment of the present invention. In these figures, elements that are the same as or similar to those in the above embodiment are given the same reference numerals as those in the above embodiment.

[0038] <Capacitor C1> 3 shows a capacitor as another example of the use of the conductive film A1. The capacitor C1 shown in the figure is a multilayer capacitor, which is a type of solid capacitor. However, the specific configuration of the capacitor according to the present invention is not limited in any way.

[0039] The capacitor C1 includes an external electrode 61, an external electrode 62, an internal electrode 63, an internal electrode 64, and a dielectric 65. The internal electrodes 63 and 64 are made of conductive films A1. The multiple internal electrodes 63 and the multiple internal electrodes 64 are stacked on top of each other with the dielectric 65 sandwiched between them. The external electrode 61 is electrically connected to the multiple internal electrodes 63. The external electrode 62 is electrically connected to the multiple internal electrodes 64.

[0040] In the capacitor C1, the internal electrodes 63, 64 made of the conductive film A1 also have excellent conductivity and flexibility. Therefore, when the capacitor C1 is used, for example, if an external impact is applied to the capacitor C1, it is possible to prevent the internal electrodes 63, 64 from being damaged. Furthermore, even if the internal electrodes 63, 64 are deformed by an impact, they are expected to maintain good conductivity. Furthermore, the internal electrodes 63, 64 made of the conductive film A1 have the advantage of being less susceptible to corrosion than electrodes made of metal, etc.

[0041] <Dielectric elastomer transducer D1> FIG. 4 shows a dielectric elastomer transducer as another example of using the conductive film A1. The dielectric elastomer transducer D1 shown in the figure comprises a pair of dielectric elastomer elements 71 and a support member 72. However, the specific configuration of the dielectric elastomer transducer according to the present invention is not limited in any way. The pair of dielectric elastomer elements 71 comprises a dielectric elastomer layer 711 and a pair of electrode layers 712. The dielectric elastomer layer 711 is made of, for example, a silicone-based material, an acrylic-based material, or a nitrile-based rubber. The pair of electrode layers 712 comprises the conductive film A1.

[0042] The support member 72 includes an inner peripheral member 721, a pair of outer peripheral members 722, and multiple rods 723. The support member 72 is preferably made of an insulating material, and a wiring layer may be formed on its surface to provide electrical continuity with the pair of electrode layers 712. The inner peripheral member 721 is fixed to the inner peripheral portions of each of the pair of dielectric elastomer elements 71. The pair of outer peripheral members 722 are individually fixed to the outer peripheral portions of each of the pair of dielectric elastomer elements 71. The multiple rods 723 maintain the pair of outer peripheral members 722 spaced apart from each other. This maintains the pair of dielectric elastomer elements 71 in a truncated cone shape under tension. A portion of the support member 72 may be made of a conductive material. This portion made of a conductive material can be used, for example, as a conductive path between the electrode layers 712 and an external circuit. For example, the rod 723 may be made of a conductive material, and the electrode layers 712 of the pair of dielectric elastomer elements 71 that are connected to ground may be electrically connected to each other via the rod 723. In this case, the number of wires for connecting the pair of dielectric elastomer elements 71 to an external circuit can be reduced.

[0043] In the dielectric elastomer transducer D1, the electrode layer 712 made of the conductive film A1 also has excellent conductivity and flexibility, so that the electrode layer 712 can easily follow the expansion and contraction of the dielectric elastomer layer 711 when the dielectric elastomer transducer D1 is in use.

[0044] The conductive film, conductive film manufacturing method, electrode, battery, capacitor, and dielectric elastomer transducer according to the present invention are not limited to the above-described embodiments. The specific configurations of each part of the conductive film, conductive film manufacturing method, electrode, battery, capacitor, and dielectric elastomer transducer according to the present invention can be freely designed in various ways. [Explanation of symbols]

[0045] A1: Conductive film B1:Battery C1: Capacitor D1: Dielectric elastomer transducer 51: Positive electrode case 52: Negative terminal 53: Electrode 54: Electrode 55: Separator 61,62: External electrode 63,64: Internal electrode 65: Dielectric 71: Dielectric elastomer element 72: Support member 711: Dielectric elastomer layer 712: Electrode layer 721: Inner peripheral member 722: Peripheral member 723: Rod

Claims

1. a conductive polymer; carbon nanotubes dispersed in the conductive polymer; A conductive film that is stretchable by elastic deformation.

2. 2. The conductive film according to claim 1, wherein the stretching rate is 1% to 100%, where the length in the natural state is 100%.

3. A method for manufacturing a conductive film that is stretchable and includes a conductive polymer and carbon nanotubes dispersed in the conductive polymer, the method comprising: A method for producing a conductive film, comprising a step of dispersing carbon nanotubes in a conductive polymer solution.

4. An electrode formed using the conductive film according to claim 1 or 2.

5. A battery comprising the electrode according to claim 4.

6. A capacitor comprising the electrode according to claim 4.

7. A dielectric elastomer transducer comprising the electrode of claim 4.

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