TWI700852B - Electrode for battery and biochemical fuel cell - Google Patents

Abstract

The present invention provides a battery electrode and a biochemical fuel cell that can increase the output.

The battery electrode 1 of the present invention includes: a skeleton 2 formed by laminating a plurality of carbon fibers 3 to form a three-dimensional network structure; a carbon nanotube structure 5 formed on the surface of the plurality of carbon fibers 3, the carbon nanotube The structure 5 is a network structure formed by a plurality of carbon nanotubes 6 directly connected to each other, and is directly fixed to the surface of the carbon fiber 3. Since the skeleton 2 does not need to be cohesive through an adhesive, it does not hinder the flow of electrolyte. The specific surface area of the battery electrode can be increased, and the carbon nanotube is directly fixed to the carbon fiber 3 without penetrating the insulator. Therefore, the resistance increase of the battery electrode can be suppressed more than before. When applied to the battery, the battery's performance can be improved. Output.

Description

Electrode for battery and biochemical fuel cell

The invention relates to an electrode for a battery and a biochemical fuel cell.

In recent years, biochemical fuel cells have attracted attention as fuel cells that use enzymes as catalysts instead of metal catalysts such as platinum. The biochemical fuel cell system uses redox enzymes to oxidize fuel and reduce oxygen to convert chemical energy into electrical energy.

In order to increase the output of this biochemical fuel cell, various improvements have been made.

For example, Patent Document 1 discloses an electrode in which zirconia and Ketjenblack (Ketjenblack, also known as superconducting carbon black) are bonded to carbon fiber cloth with polytetrafluoroethylene (PTFE) to increase the specific surface area of the electrode. .

【Prior Technical Literature】

Patent literature

Patent Document 1: Japanese Patent Application Publication No. 2012-28181

However, in the electrode disclosed in Patent Document 1, PTFE as an adhesive is clogged in the pores of the carbon fiber cloth, and the carbon fiber cloth is agglomerated by PTFE, which hinders the flow of electrolyte when used in the electrode of a biochemical fuel cell. Biofuel It is difficult to increase the output of the battery.

In addition, the electrode disclosed in Patent Document 1 has an increased specific surface area due to the adhesion of Ketjen black to the carbon fiber cloth. However, the Ketjen black and the carbon fiber cloth are fixed through the insulator PTFE. When used as an electrode of a biochemical fuel cell, the internal resistance of the biochemical fuel cell increases, and the output of the biochemical fuel cell becomes difficult to increase.

Here, the object of the present invention is to provide a battery electrode and a biochemical fuel cell that can further increase the output.

The battery electrode system of the present invention includes: a skeleton formed by laminating a plurality of carbon fibers to form a three-dimensional network structure; a carbon nanotube structure formed on the surface of the plurality of carbon fibers, the carbon nanotube structure being A plurality of carbon nanotubes form a network structure directly connected to each other and are directly fixed on the surface of the carbon fiber.

The biochemical fuel cell of the present invention uses the battery electrode described in any one of items 1 to 7 of the scope of patent application.

In the battery electrode of the present invention, the skeleton of the three-dimensional network structure does not need to be cohesive through the adhesive, so it does not hinder the flow of electrolyte, and can increase the specific surface area of the battery electrode, and the carbon nanotube does not penetrate the insulator It is directly fixed to the carbon fiber, so the increase in the resistance of the battery electrode can be suppressed more than before, and when applied to a battery, the output of the battery can be improved.

Since the biochemical fuel cell of the present invention does not hinder the flow of electrolyte, it can generate electric energy more efficiently than before. In addition, due to the comparison of battery electrodes The increased surface area can increase the current density more than before, so the output of the battery can be improved.

1‧‧‧Electrode for battery

2‧‧‧Frame

3‧‧‧Carbon Fiber

4‧‧‧Connecting part

5‧‧‧Carbon Nanotube Structure

6‧‧‧Carbon Nanotube

Fig. 1 is a schematic diagram showing an enlarged part of a battery electrode.

Fig. 2 is an SEM image of the surface of the battery electrode.

Fig. 3A is an enlarged SEM image showing the carbon fiber of the battery electrode.

Figure 3B shows a more enlarged SEM image of the carbon fiber of the battery electrode.

(1) Biochemical fuel cell of this embodiment

Regarding the biochemical fuel cell of this embodiment, as the anode electrode and the cathode electrode, except for the battery electrode of this embodiment described below, a conventional biochemical fuel cell configuration can be used.

For example, the biochemical fuel cell of this embodiment has a configuration in which the anode electrode and the cathode electrode are arranged in an electrolyte. The electrolyte contains a fuel that emits electrons through oxidation; a redox enzyme that oxidizes the fuel at the anode electrode and reduces oxygen at the cathode electrode; an electron transfer medium that mediates the transfer of electrons between the enzyme and the electrode.

As fuels, sugars, alcohols, organic acids, amines, hydrogen, and inorganic compounds can be used as energy sources and all reducing substances can be used.

More specifically, as the fuel, alcohols such as methanol, ethanol, propanol, glycerin, and polyvinyl alcohol; sugars such as glucose, fructose, and sorbose; aldehydes such as formaldehyde and acetaldehyde; and mixtures thereof can be used.

As a redox enzyme, it can be used to oxidize the above fuel, The enzyme that reduces oxygen can be selected according to the fuel used.

For example, as redox enzymes, laccase (laccase), ascorbate oxidase, bilirubinase (BOD), glucose dehydrogenase (GDH), alcohol dehydrogenase (ADH), aldehyde dehydrogenase, glucose oxidation can be used Enzyme (GOD), alcohol oxidase (AOD), and aldehyde oxidase, etc.

Redox enzymes may be used alone or in combination of two or more kinds.

As the electron transfer medium, for example, metal complexes with metal elements such as Os, Fe, Ru, Co, Cu, Ni, V, Mo, Cr, Mn, Pt, and W as the central metal can be used; quinone, benzoquinone, onion Quinones and naphthoquinones; heterocyclic compounds such as viologen, methyl viologen and benzyl viologen. The electron transfer medium can be selected according to the redox enzyme used. In addition, it is better to use an electronic transfer medium, but it may not be used.

(2) The structure of the battery electrode of this embodiment

As shown in FIG. 1, the battery electrode 1 includes a skeleton 2 and a carbon nanotube (hereinafter referred to as CNT) structure 5 formed on the surface of the skeleton 2. The skeleton 2 has a plurality of carbon fibers 3 and a connecting portion 4 connecting the carbon fibers 3 to each other, and forms a three-dimensional network structure in which the plurality of carbon fibers 3 are stacked. Actually, the battery electrode 1 is in the shape of a plate, but for the convenience of description, Fig. 1 shows a part of the battery electrode 1 enlarged.

The skeleton 2 is a part of the contact part of a plurality of carbon fibers 3 intertwined with each other, a part of adjacent carbon fibers 3 in contact with each other, and a part of the mesh formed by the plurality of carbon fibers 3, connected by an adhesive such as resin The part 4 is formed, and the carbon fibers 3 are connected to each other by the connecting part 4.

In the case of this embodiment, the connecting portion 4 is carbonized to have conductivity. Therefore, the frame 2 has higher conductivity than when the connecting portion 4 is formed of an insulator such as resin. The connecting portion 4 is formed by, for example, a resin composition made of Teflon (registered trademark) or the like attached to the frame 2 and the resin composition is carbonized in this state.

The skeleton 2 is not limited to a three-dimensional network structure formed of carbon fibers, and may not have the connecting portion 4. As the skeleton 2, for example, commercially available carbon paper, carbon nonwoven fabric, carbon fiber cloth, and the like can be used. In the case of this embodiment, the frame 2 is carbon paper.

In addition, in the case of this embodiment, the surfaces of the carbon fibers 3 and the connecting portion 4 forming the skeleton 2 are oxidized, and functional groups such as hydroxyl groups and carboxyl groups are formed on part of the surfaces of the carbon fibers 3 and the connecting portions 4.

A CNT structure 5 is formed on the surface of the carbon fiber 3 forming the skeleton 2. The CNT structure 5 includes a plurality of CNTs 6 uniformly dispersed. A plurality of CNT6 are directly connected to each other to form a network structure. The direct connection here refers to the state in which CNT6 are not covered with dispersant, surfactant, adhesive, etc., and are entangled with each other, that is, CNT6 is not connected to each other through media such as adhesive, dispersant, surfactant, etc. , Including physical connection (simple contact), chemical connection. Such a CNT structure 5 is also formed on the surface of the connecting portion 4.

The CNT structure 5 preferably has an average thickness of 500 nm or less. When the average thickness of the CNT structure 5 exceeds 500 nm, the CNT structure 5 covering the surface of the carbon fiber 3 becomes excessive. As a result, the proportion of CNT6 agglomerated becomes higher, which reduces electrical conductivity or thermal conductivity, and restricts the function of CNT structure 5 derived from carbon fiber 3. In addition, when the battery electrode 1 is used as an electrode of a biochemical fuel cell, It hinders the circulation of electrolyte, redox enzymes, etc., and there is a concern that the output performance of the battery will decrease.

In addition, the average thickness of the CNT structure 5 is measured by comparing the scanning electron microscope (Scanning Electron Microscope: SEM) images of the carbon fibers 3 before and after the formation of the CNT structure 5. Specifically, first, the diameter of the carbon fibers 3 before the formation of the CNT structure 5 is measured at 30 places in the SEM image of the carbon fibers 3 before the formation of the CNT structure 5, and the average of the carbon fibers 3 before the formation of the CNT structure 5 is calculated. path. Next, the diameter of the carbon fiber 3 after the formation of the CNT structure 5 is measured at 30 places in the SEM image of the carbon fiber 3 after the formation of the CNT structure 5, and the average diameter of the carbon fiber 3 after the formation of the CNT structure 5 is calculated. Finally, the average diameter of the carbon fibers 3 before the formation of the CNT structure 5 is subtracted from the average diameter of the carbon fibers 3 after the formation of the CNT structure 5 to calculate the average thickness of the CNT structure 5.

The average thickness of the CNT structure 5 is more preferably 5 nm or more and 100 nm or less. As long as the thickness of the CNT structure 5 is within the above range, the CNT6 is dispersed on the surface of the carbon fiber 3 and directly connected to each other to form a good CNT6 network structure. The network structure here is not limited to the case of forming a whole network on the surface of the carbon fiber 3, but also includes a structure in which multiple network structures exist independently, a structure in which multiple network structure parts are directly connected, and a network structure on the surface of carbon fiber 3 and The other carbon fibers 3 or the network structure on the surface of the connecting portion 4 are directly connected to each other.

CNT6 is preferably multilayered. In addition, the length of CNT6 is preferably 0.1 μm or more and 50 μm or less. When the length of CNT6 is 0.1 μm or more, CNT6 is entangled with each other and directly connected. Also, when the length of CNT6 is 50μm or less, it is easy to Disperse evenly. On the other hand, when the length of CNT6 is less than 0.1 μm, it becomes difficult for CNT6 to be entangled with each other. In addition, when the length of CNT6 exceeds 50 μm, it becomes easy to aggregate.

CNT6 preferably has a diameter of 30 nm or less. When the diameter of CNT6 is 30nm or less, it is rich in flexibility, deforms along the curvature of the carbon fiber 3 or the surface, and easily forms a network structure. On the other hand, when the diameter of CNT6 exceeds 30 nm, it becomes non-flexible, and it is difficult to deform along the surface of the carbon fiber 3, so it is difficult to form a network structure.

The diameter of CNT6 is more preferably 20 nm or less. Also, before attaching the CNT6 to the carbon fiber 3 with the diameter of the CNT6 according to the method described below, take out a part of the CNT6 used for attachment, and photograph the CNT6 with a transmission electron microscope (TEM: Transmission Electron Microscope). The image is the measured average diameter.

In addition, the surface of CNT6 is oxidized to form functional groups such as hydroxyl and carboxyl on a part of the surface of CNT6. Since a hydroxyl group or a carboxyl group is formed on the surface of CNT6, when the battery electrode 1 is applied to an electrode of a battery, the electron transfer of the active material of the electrode is performed through the hydroxyl group or the carboxyl group, and the electron transfer proceeds more smoothly. As a result, the battery using the battery electrode 1 for the electrode can efficiently generate electric energy and increase the output of the battery. When the battery electrode 1 is used as an electrode of a biochemical fuel cell, the electron transfer between CNT6 and the electron transfer medium proceeds through the hydroxyl group or the carboxyl group, the electron transfer becomes smoother, and the battery output is improved.

The CNT6 constructed in this way is fixed on the surface of the carbon fiber 3 and the connecting part 4 at a ratio of 0.001wt% to 2wt% relative to the skeleton 2. good. When the ratio of CNT6 is within the above range, a portion not covered with CNT6 is formed on the surface of the carbon fiber 3. These parts that are not covered with CNT6 are not covered with adhesives, etc., exposing the surface of the carbon fiber 3. Thereby, the skeleton 2 does not impair the function of CNT6. The ratio of CNT6 relative to the skeleton 2 is preferably 0.005 wt% or more and 1 wt% or less, and more preferably 0.01 wt% or more and 0.1 wt% or less.

Such a CNT structure 5 is directly fixed to the surface of the carbon fiber 3. In other words, CNT6 is neither on the surface of the carbon fiber 3, but also covered and fixed to the surface of the carbon fiber 3 with an adhesive, dispersant, surfactant, etc., nor is it fixed to the carbon fiber 3 through an adhesive, dispersant, surfactant, etc. , But directly fixed to the surface of the carbon fiber 3. The fixing system here includes the bonding of carbon fiber 3 and CNT6 with Chidvar force, the chemical bonding of carbon fiber 3 and CNT6 through the hydroxyl or carboxyl group formed on the surface of carbon fiber 3, and the bonding of carbon fiber 3 and CNT6 through the hydroxyl or carboxyl group formed on the surface of CNT6 Chemical bonding.

In addition, the CNT structure 5 is also directly fixed to the surface of the connecting portion 4 as well. In addition, as long as the functions of the framework 2 and CNT6 are not limited, the battery electrode 1 may include carbon fibers 3 and CNT6 bonded through an adhesive or a dispersant.

(3) Manufacturing method of battery electrode of this embodiment

Next, the manufacturing method of the electrode 1 for a battery is demonstrated. The battery electrode 1 consists of (3-1) CNT production step, (3-2) CNT dispersion step using the produced CNT, and (3-3) CNT structure formation step on the surface of carbon fiber using CNT dispersion Become. Hereinafter, each step will be explained in order.

(3-1) CNT production steps

CNT6 can be produced using, for example, the thermal CVD method described in JP 2007-126311 A. In this case, first, a film made of aluminum and iron is formed on a silicon substrate The formed catalyst film is heat-treated to form catalyst particles on the surface of the catalyst film. Next, the hydrocarbon gas is brought into contact with the catalyst particles in a heating environment, and the catalyst particles start to grow into CNT6, thereby making CNT6.

The CNT6 produced in this way is aligned in a straight line in the vertical direction facing the surface of the substrate on the substrate, and has a so-called high aspect ratio of hundreds to thousands. Cut CNT6 from the substrate for use. The cut CNT6 may contain catalyst residues such as catalyst particles or fragments. It is expected that the catalyst residue can be removed from CNT6 by high-temperature annealing and acid treatment in an inert gas.

In addition, CNT6 can also be obtained by other production methods such as arc discharge method and laser evaporation method. However, it is desirable to produce CNT6 using a method that does not contain impurities (catalyst residue, etc.) other than CNT6 as much as possible. Regarding these impurities, it is desirable to remove them in the same manner as the catalyst residue.

(3-2) Steps to generate CNT dispersion using the produced CNT

First, the CNT6 produced by the above method is oxidized in an oxygen environment at a predetermined temperature. At this time, on a part of the surface of CNT6, functional groups such as hydroxyl or carboxyl groups are formed on the surface of CNT6. An ozone processor can be used to oxidize CNT6, or, for example, CNT6 can be immersed in a mixed acid containing a 1:1 ratio of nitric acid and sulfuric acid to be oxidized.

Next, CNT6 whose surface has been oxidized is thrown into a dispersion solvent so as to have a predetermined mass concentration, and the CNT6 is uniformly dispersed using a homogenizer, high pressure shear, ultrasonic disperser, etc., to thereby produce a CNT dispersion. The resulting CNT dispersion is dispersed in a dispersion solvent in a physically separated and untangled state per CNT6, and the ratio of aggregates of two or more CNT6 aggregates relative to the number of CNT6 is 10% or less. CNT6 is a condensed collection The ratio of objects is determined by measuring the number of CNT6 and the number of aggregates from the TEM image.

As a dispersion solvent, water, alcohols (ethanol, methanol, isopropanol, etc.), organic solvents (toluene, acetone, THF, MEK, hexane, n-hexane, ether, xylene, methyl acetate, ethyl acetate, etc.) can be used Wait). In addition, as long as the functions of the skeleton 2 and CNT6 are not limited, the dispersion may contain a dispersant, a surfactant, an adhesive, and the like.

(3-3) Steps of forming CNT structure on the surface of carbon fiber using CNT dispersion

First, prepare carbon nano paper cut into a predetermined size as the skeleton 2. In addition, in the case of this embodiment, the prepared carbon paper has the above-mentioned connecting portion 4.

Next, in an oxygen environment, the skeleton 2 is heated at a predetermined temperature to oxidize the surface of the carbon fiber 3. At this time, a part of the surface of the carbon fiber 3 forms a functional group such as a hydroxyl group or a carboxyl group. The surface of the carbon fiber 3 can be oxidized using an ozone processor, or, for example, the skeleton 2 can be immersed in a mixed acid containing nitric acid and sulfuric acid in a ratio of 1:1 to be oxidized. When the surface of the carbon fiber 3 is oxidized, the surface of the connecting portion 4 is also oxidized at the same time.

Next, in the CNT dispersion liquid produced as described above, the skeleton 2 whose surface has been oxidized on the carbon fiber 3 is impregnated, and mechanical energy such as shearing or ultrasonic waves is applied to the CNT dispersion liquid to form a CNT structure 5 on the surface of the carbon fiber 3.

When mechanical energy such as shearing or ultrasonic waves is applied to the CNT dispersion, the CNT6 in the CNT dispersion repeatedly undergoes a reversible reaction state between the dispersed state and the aggregated state. This reversible reaction state also occurs when the skeleton 2 is immersed in the CNT dispersion. Therefore, the dispersion of CNT6 also occurs on the surface of the carbon fiber 3 of the skeleton 2 A state of reversible reaction between the state and the aggregated state. When the CNT6 moves from the dispersed state to the aggregated state, CNT6 is wound and adhered to the surface of the carbon fiber 3 to form a CNT structure 5 on the carbon fiber 3.

When the CNT6 aggregates, the CNT6 is bonded to the surface of the carbon fiber 3 via the Van der Waals force acting between the carbon fiber 3 and the CNT6 through the combination of the hydroxyl group or the carboxyl group formed on the surface of the carbon fiber 3.

At this time, the CNT 6 is also attached to the surface of the connecting portion 4 in the same manner, and the CNT structure 5 is also formed on the connecting portion 4.

Finally, the skeleton 2 is taken out from the CNT dispersion liquid to obtain the battery electrode 1 in which the CNT structure 5 in which the CNT 6 has a network structure directly connected to each other is formed on the surface of the carbon fiber 3.

Furthermore, by repeating the step (3-3) of forming a CNT structure on the surface of a carbon fiber using a CNT dispersion, the battery electrode 1 with a thicker CNT structure 5 can be formed. In this case, for the CNT dispersion used after the second time, add CNT6 to a predetermined amount each time, while adjusting the concentration of CNT6, and applying mechanical energy to disperse CNT6.

(4) Function and effect

The battery electrode 1 of the present embodiment includes a skeleton 2 formed by laminating a plurality of carbon fibers 3 to form a three-dimensional network structure; and a CNT structure 5 formed on the surface of the plurality of carbon fibers 3. In addition, the CNT structure 5 is a structure in which a plurality of CNTs 6 form a network structure directly connected to each other and are directly fixed to the surface of the carbon fiber 3.

This kind of battery electrode 1 is different from the conventional ones. Since the CNT6 is directly fixed to the carbon fiber 3 without using an adhesive, there is no need to form a three-dimensional network skeleton 2 Through the adhesion of the adhesive, it will not hinder the circulation of the electrolyte. When applied to the battery, the output of the battery can be improved.

In addition, since the battery electrode 1 includes the CNT structure 5 formed on the surface of the carbon fiber 3, the specific surface area can be increased, and the CNT6 is directly fixed to the carbon fiber 3 without penetrating the insulator. Therefore, compared with the past, the battery electrode can be suppressed. 1 Increase in resistance, so when applied to batteries, the output of the battery can be improved.

The biochemical fuel cell of this embodiment is constructed using the battery electrode 1 of this embodiment.

Since this type of biochemical fuel cell is not obstructed in the flow of electrolyte or enzymes, it generates electric energy more efficiently than in the past. In addition, the battery electrode 1 has a larger specific surface area. Therefore, the current density can be increased compared with the past and the battery can be improved. Output.

(5) Example

The battery electrode 1 of Example 1 was produced in the procedure shown in the above-mentioned "(3) Method for manufacturing battery electrode of this embodiment". In Example 1, a multilayer carbon nanotube with a diameter of 10-15 nm and a length of 100 μm or more grown on a silicon substrate according to the above-mentioned thermal CVD method was used as the CNT6.

In addition, in Example 1, the produced CNT6 was immersed in a mixed acid containing a 3:1 ratio of nitric acid and sulfuric acid, washed and filtered and dried to remove catalyst residue. In addition, in Example 1, when the CNT6 was immersed in a mixed acid in order to remove the catalyst residue, the surface of the CNT6 was also oxidized, so there was no need to perform an additional oxidation step of the CNT6.

Furthermore, in Example 1, the length of the produced CNT6 is Therefore, after putting CNT6 into methyl ethyl ketone as a dispersion solvent, CNT6 is pulverized into a length of 0.5-10 μm for CNT6 with an ultrasonic homogenizer, and CNT6 is uniformly dispersed. The concentration of CNT6 in the CNT dispersion is 0.01 wt%.

Also, in Example 1, carbon paper made by Toray Co., Ltd. (model: TGP-H-120) was used, cut into a size of 100×100 mm as the skeleton 2, and placed in a closed container (the volume of 1000 cc contains 1 cc of oxygen) Heat the skeleton 2 at 500°C for 10 minutes.

The CNT dispersion in which the skeleton 2 was immersed was subjected to ultrasonic waves of 28 kHz and 40 kHz for 10 seconds to adhere CNT 6 to the surface of the carbon fiber 3, thereby fabricating the battery electrode 1. After that, the skeleton 2 was taken out from the CNT dispersion and dried on a hot plate at 80° C. to obtain the battery electrode 1 of Example 1 containing about 0.1% by weight of CNT6 relative to the skeleton 2.

The surface of the battery electrode 1 of Example 1 was observed with a scanning electron microscope (Scanning Electron Microscope: SEM). As shown in Figure 2, it can be confirmed that the skeleton 2 has a contact part of a plurality of carbon fibers 3 intertwined with each other, a part where adjacent carbon fibers 3 contact each other, and a connection part of a mesh formed by a plurality of carbon fibers 3 4. The connecting portion 4 has a skeleton 2 before the CNT structure 5 is formed on the surface of the carbon fiber 3. Except for the connection portion 4, no adhesion was observed in the skeleton 2 of the battery electrode 1. Therefore, it was confirmed that in the battery electrode 1, the CNT structure 5 was formed on the surface of the carbon fiber 3 forming the skeleton 2, but no agglomeration occurred in the skeleton 2.

In addition, as shown in Figure 3A, it can be confirmed that CNTs formed by a network structure in which a plurality of CNTs 6 are directly connected to each other are formed on the surface of the carbon fiber 3. Structure 5.

Furthermore, as shown in Figure 3B, CNT6 can be directly fixed on the surface of carbon fiber 3.

Use platinum as the counter electrode, Ag-AgCl electrode as the reference electrode, battery electrode 1 of Example 1 as the test electrode, PH7 phosphate buffer (0.1 mol/L) as the electrolyte, and BOD as the enzyme. The oxygen is reduced in the electrolyte, and the oxygen reduction current is measured. In addition, as Comparative Example 1, the test electrode was replaced with a conventional electrode made of carbon paper and Ketjen black adhered with PTFE, and the oxygen reduction current was measured under the same conditions. As a result, it was confirmed that the use of the battery electrode 1 of Example 1 as a test electrode has an increase in oxygen reduction current compared to the use of a conventional electrode.

(6) Variations

In addition, the present invention is not limited to the above-mentioned embodiment, and various modifications can be implemented within the scope of the gist of the present invention.

Although the foregoing embodiment described the case where the electron transfer medium and the redox enzyme are present in the electrolyte, the present invention is not limited to this, and the electron transfer medium and the redox enzyme may be fixed to the battery electrode 1.

Although the above embodiment describes the case where the battery electrode 1 of the present invention is used for both the anode electrode and the cathode electrode of a biochemical fuel cell, the present invention is not limited to this, and only either the anode electrode or the cathode electrode may use the battery electrode 1 can.

Although the foregoing embodiment describes the case where the battery electrode 1 of the present invention is used as an electrode of a biochemical fuel cell, the present invention is not limited to this, and can be used as an electrode of a battery such as a fuel cell and a lithium ion secondary battery.

In addition, although the above embodiments describe the case where a plurality of CNT6 are directly fixed on the surface of the carbon fiber 3, the present invention is not limited to this. The plurality of CNT6 on the surface of the carbon fiber 3 can be directly fixed by a part of the surface of the CNT6 as an adhesion component, or At least a part other than the attachment part may be physically fixed by providing an adhesive member.

At this time, in the battery electrode of the modified example, an adhesive member is provided adjacent to the attachment portion of CNT6. The next member is formed of a cured product of thermosetting resin, and for example, an epoxy resin or a resin emulsified adhesive can be used. Then, the member physically fixes the CNT6 to the carbon fiber 3 by wetting.

As a result, the battery electrode of the modified example has CNT6 around the attached part, and at least a part of the CNT6 attached part is reinforced with an adhesive member. Therefore, it can be firmly fixed by the carbon fiber 3 and used in a battery. In this case, it is possible to suppress a decrease in battery output or a short circuit between electrodes caused by the peeling of CNT6, and the durability of the battery can be improved.

The battery electrode of this modified example is fixed to the surface of the carbon fiber 3 without covering the bonding member together with the carbon fiber 3, nor is it fixed to the carbon fiber 3 via the bonding member, so that the electrode caused by the installation of the bonding member can be suppressed The decrease in area and the increase in resistance between CNT6 and carbon fiber 3 can improve the output and durability of the battery when used in batteries.

1‧‧‧Electrode for battery

2‧‧‧Frame

3‧‧‧Carbon Fiber

4‧‧‧Connecting part

5‧‧‧Carbon Nanotube Structure

6‧‧‧Carbon Nanotube

Claims (8)

An electrode for a battery, comprising: a skeleton formed by laminating a plurality of carbon fibers to form a three-dimensional network structure; and a carbon nanotube structure formed on the surface of the plurality of carbon fibers; characterized in that: the carbon nanotube The structure is a network structure formed by a plurality of carbon nanotubes directly connected to each other and is directly fixed on the surface of the carbon fiber. The ratio of the plurality of carbon nanotubes to the skeleton is 0.01wt% or more and 0.1wt% or less . According to the battery electrode according to the first item of the scope of patent application, the average thickness of the carbon nanotube structure is 500 nm or less. According to the first or second battery electrode of the scope of patent application, at least one of a hydroxyl group and a carboxyl group is formed on the surface of the carbon nanotube. The battery electrode according to item 1 or 2 of the scope of patent application, wherein the surface of the carbon fiber is oxidized. According to the battery electrode according to item 4 of the scope of patent application, at least one of a hydroxyl group and a carboxyl group is formed on the surface of the carbon fiber. The battery electrode according to item 5 of the patent application, wherein the carbon fiber and the carbon nanotube are connected through at least one of the hydroxyl group and the carboxyl group. According to the battery electrode according to item 1 or 2 of the scope of patent application, wherein the skeleton is a plurality of the carbon fibers connected to each other by a connecting portion, and the connecting portion is carbonized. A kind of biochemical fuel cell, using the battery of item 1 or 2 in the scope of patent application Use electrodes.

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