JP7063128B2 - Conductive substrate for enzyme power generation device, electrode for enzyme power generation device and enzyme power generation device - Google Patents

Description

The present invention relates to a conductive substrate for an enzyme power generation device, an electrode for an enzyme power generation device, and an enzyme power generation device.

In recent years, research and development have been conducted on enzyme power generation devices that use enzymes as electrode catalysts and generate power using sugars, alcohols and other biomass resources as fuel. Enzymatic power generation devices typically include electrodes immersed in a solution containing fuel, of which the anode contains an enzyme that promotes the oxidation of the fuel and the oxidation of the fuel at the anode (eg glucose to glucono). The electrons taken out by (change to lactone) move to the cathode side, and oxygen is reduced to generate water (H ₂ O). The movement of electrons generated in the above process is used for power generation.
Furthermore, using the principle of an enzyme power generation device, it can be used as a self-power generation sensor that generates power while detecting an object.
Enzymatic power generation devices that utilize enzyme reactions can simplify the structure of the battery, can operate at room temperature, and have the features of enzyme fuel cells such as high compatibility with the environment and living organisms. Since the type sensor doubles as a power source and a sensor, it is possible to reduce the size, weight, and cost, and it is possible to obtain high sensing accuracy due to high substrate selectivity by an enzyme.
From the above, the enzyme power generation device has been studied as a power source and a sensor device in a field unsuitable for conventional batteries such as wearable devices and disposable devices.
In order to obtain high output and high sensing accuracy, a conductive base material having good conductivity is required, but a conductive base material using a metal has problems in terms of cost and oxidation over time. Further, when it is used as a wearable device, a disposable device, or the like, there are problems in terms of environment, safety, biocompatibility, and the like. On the other hand, various studies have been made on conductive compositions using conductive carbon that does not use metal, but the conductivity is often insufficient, and there remains a problem.
Patent Document 1 describes a method of using a carbon paste for a conductive layer, and Patent Document 2 describes a method of using a conductive paste composed of carbon black, biocarbon, vapor phase carbon fiber and activated carbon on a non-woven fabric. However, since the conductivity is not sufficient, there remains a problem that it is difficult to stably exert a high output.
Patent Document 3 describes a method of using carbon paper, carbon cloth, carbon sponge, or the like for the electrodes. Although it has excellent conductivity, there are still problems in using it for wearable devices, such as cracks due to deformation and difficulty in thinning.

WO2016 / 062419 WO2013 / 065581 Japanese Unexamined Patent Publication No. 2012-252955

An object of the present invention is to provide a conductive substrate having excellent conductivity and having excellent conductivity and flexibility of the conductive layer.

As a result of diligent studies, the present inventors have come to solve the above-mentioned problems.
That is, the present invention is a conductive base material for an enzyme power generation device having a non-conductive base material and a conductive layer arranged on the non-conductive base material, and the conductive layer is a conductive carbon material (that is, A) and binder (B) are included.
The density of the conductive layer is 0.9 to 2.2 g / cm ³ .
The present invention relates to a conductive substrate for an enzyme power generation device.

The present invention also relates to the conductive substrate for an enzyme power generation device, characterized in that the volume resistivity of the conductive layer is 1 × 10 ⁻² Ω · cm or less.

The present invention also relates to the conductive substrate for an enzyme power generation device, wherein the binder (B) contains a water-soluble resin (Ba) or water-dispersed resin fine particles (Bb).

The present invention also relates to the conductive substrate for an enzyme power generation device, wherein the conductive carbon material (A) contains at least graphite (AA).

Further, in the present invention, the content of the carbon material (A) in the total solid content of the conductive layer of 100% by mass is 50 to 90% by mass, and the graphite (Aa) contained in the carbon material (A) has a content of 50 to 90% by mass. The present invention relates to the conductive substrate for an enzyme power generation device, wherein the mass ratio (Aa) / (A) × 100 is 25 to 100% by mass.

The present invention also relates to the conductive substrate for an enzyme power generation device, wherein the content of the binder (B) in the total solid content of the conductive layer is 100% by mass is 5 to 50% by mass.

The present invention also relates to an electrode for an enzyme power generation device, which comprises using the conductive substrate for an anode and a cathode.

The present invention also relates to an enzyme power generation device formed by using the electrodes for the enzyme power generation device as an anode and a cathode.

In the conductive layer containing the conductive carbon material (A) and the binder (B), since the density of the conductive layer is within a specific range, the carbon materials in the conductive layer have good contact with each other, so that the conductivity is excellent. It is possible to form a network and provide a conductive base material having excellent conductivity.

<Conductive base material>
The conductive substrate of the present invention requires a conductive carbon material (A) and a binder (B) on at least one surface of a non-conductive substrate such as paper or PET (polyethylene terephthalate) film. A conductive composition containing a solvent can be applied, and if necessary, a press treatment or the like can be performed to form a conductive layer to obtain a conductive substrate.

(Conductive carbon material (A))
In the present invention, the conductive carbon material (A) is used as the conductive material from the viewpoint of disposableness, biocompatibility and the like. The carbon material is not particularly limited as long as it is a conductive carbon material. Examples of the conductive carbon material (A) include graphite, carbon black, conductive carbon fibers (carbon nanotubes, carbon nanofibers, carbon fibers), graphene, fullerene and the like. These can be used alone or in combination of two or more.

Further, as the carbon material (A) of the conductive layer, it is preferable to contain graphite (Aa). By having graphite in the conductive layer, a conductive base material having excellent conductivity can be obtained. The mass ratio (Aa) / (A) × 100 of graphite (Aa) contained in the conductive carbon material (A) contained in the conductive layer is preferably 25 to 100% by mass, more preferably. It is 50 to 100% by mass, more preferably 50 to 90% by mass.

As the graphite (Aa), for example, artificial graphite, natural graphite, or the like can be used. Artificial graphite is made by artificially orienting irregularly arranged micrographite crystals by heat treatment of amorphous carbon, and is generally manufactured using petroleum coke or coal-based pitch coke as the main raw material. To. As the natural graphite, spherical graphite, scaly graphite, lump graphite, earth graphite and the like can be used. It is also possible to use expanded graphite (also referred to as expandable graphite) obtained by chemically treating scaly graphite, or expanded graphite obtained by heat treatment and expansion of expanded graphite and then miniaturization or pressing. You can. Among these graphites, when used for the conductive layer of a conductive substrate, natural graphite is preferable from the viewpoint of conductivity, and flaky graphite such as spherical graphite, scaly graphite expanded graphite, and flaky graphite is preferable. ..

The average particle size of the graphite (Aa) used is preferably 0.5 to 500 μm, and particularly preferably 2 to 100 μm.

The average particle size referred to in the present invention is a particle size (D50) that becomes 50% when the volume ratio of the particles is integrated from the fine particle size distribution in the volume particle size distribution, and is generally used. It is measured with a standard particle size distribution meter, for example, a dynamic light scattering type particle size distribution meter (“Microtrack UPA” manufactured by Nikkiso Co., Ltd.).

As commercially available graphite, for example, as flaky graphite, CMX, UP-5, UP-10, UP-20, UP-35N, CSSP, CSPE, CSP, CP, CB-150, CB manufactured by Nippon Graphite Industry Co., Ltd. -100, ACP, ACP-100, ACB-50, ACB-100, ACB-150, SP-10, SP-20, J-SP, SP-270, HOP, GR-60, LEP, F # 1, F # 2, F # 3, CX-3000, FBF, BF, CBR, SSC-3000, SSC-600, SSC-3, SSC, CX-600, CPF-8, CPF-3, CPB- made by Chuetsu Graphite Co., Ltd. 6S, CPB, 96E, 96L, 96L-3, 90L-3, CPC, S-87, K-3, CF-80, CF-48, CF-32, CP-150, CP-100, CP, HF- 80, HF-48, HF-32, SC-120, SC-80, SC-60, SC-32, EC1500, EC1000, EC500, EC300, EC100, EC50 manufactured by Ito Graphite Industry Co., Ltd. 10099M manufactured by Nishimura Graphite Co., Ltd. , PB-99 and the like. Examples of the spherical natural graphite include CGC-20, CGC-50, CGB-20, and CGB-50 manufactured by Nippon Graphite Industry Co., Ltd. Examples of earth-like graphite include blue P, AP, AOP, P # 1 manufactured by Nippon Graphite Industry Co., Ltd., and APR, S-3, AP-6, 300F manufactured by Chuetsu Graphite Co., Ltd. As artificial graphite, PAG-60, PAG-80, PAG-120, PAG-5, HAG-10W, HAG-150 manufactured by Nippon Graphite Industry Co., Ltd., RA-3000, RA-15, RA- of Chuetsu Graphite Co., Ltd. 44, GX-600, G-6S, G-3, G-150, G-100, G-48, G-30, G-50, SGP-100, SGP-50, SGP-25 manufactured by SEC Carbon Co., Ltd. , SGP-15, SGP-5, SGP-1, SGO-100, SGO-50, SGO-25, SGO-15, SGO-5, SGO-1, SGX-100, SGX-50, SGX-25, SGX -15, SGX-5, SGX-1 can be mentioned.

The conductive carbon material (Ab) other than graphite is not particularly limited, but it is preferable to use carbon black or conductive carbon fiber from the viewpoint of conductivity and cost.

Carbon black includes furnace black, which is produced by continuously pyrolyzing gas or liquid raw materials in a reactor, especially acetylene black, which uses ethylene heavy oil as a raw material, and the raw material gas is burned to burn the flame to the bottom of the channel steel. Various types such as channel black that has been rapidly cooled and precipitated, thermal black that is obtained by periodically repeating combustion and pyrolysis using gas as a raw material, and acetylene black that uses acetylene gas as a raw material, alone or 2 It can be used in combination with more than one type. In addition, normally oxidized carbon black, hollow carbon, and the like can also be used.
Oxidation treatment of carbon is performed by treating carbon at a high temperature in the air or secondarily treating it with nitric acid, nitrogen dioxide, ozone, etc., for example, phenol group, quinone group, carboxyl group, carbonyl group, etc. It is a process of directly introducing (covalently bonding) an oxygen-containing polar functional group to the carbon surface, and is generally performed to improve the dispersibility of carbon. However, since the conductivity of carbon generally decreases as the amount of the functional group introduced increases, it is preferable to use carbon that has not been oxidized.

As the specific surface area of the carbon black used increases, the contact points between the carbon black particles increase, which is advantageous for lowering the internal resistance of the electrode. Specifically, the specific surface area (BET) obtained from the amount of nitrogen adsorbed is 20 m ² / g or more and 1500 m ² / g or less, preferably 50 m ² / g or more and 1500 m ² / g or less, and more preferably 100 m ² It is desirable to use the one of / g or more and 1500 m ² / g or less. If carbon black having a specific surface area of less than 20 m ² / g is used, it may be difficult to obtain sufficient conductivity, and carbon black having a specific surface area of more than 1500 m ² / g may be difficult to obtain as a commercially available material. be.
The particle size of the carbon black used is preferably 0.005 to 1 μm in primary particle size, and particularly preferably 0.01 to 0.2 μm. However, the primary particle diameter referred to here is an average of the particle diameters measured by an electron microscope or the like.

Examples of commercially available carbon black include Talker Black # 4300, # 4400, # 4500, # 5500 manufactured by Tokai Carbon, Printex L manufactured by Degusa, Raven 7000, 5750, 5250, 5000 ULTRAIII and 5000 ULTRA manufactured by Colombian. Conductex SC ULTRA, Conductex 975 ULTRA, PUERBLACK100, 115, 205, # 2350, # 2400B, # 2600B, # 3050B, # 3030B, # 3230B, # 3350B, # 3400B, # 5400B, manufactured by Mitsubishi Chemical Co., Ltd. MONARCH1400, 1300, 900, VulcanXC-72R, BlackPearls2000, Ensaco250G, Ensaco260G, Ensaco350G, SuperP-Li, etc. Examples thereof include acetylene black such as Denka Black, Denka Black HS-100, and FX-35 manufactured by Denka Black, but the present invention is not limited to these, and two or more types may be used in combination.

As the conductive carbon fiber, one obtained by firing from a raw material derived from petroleum is preferable, but one obtained by firing from a raw material derived from a plant can also be used. Further, the carbon nanotubes include a single-walled carbon nanotube in which a graphene sheet forms a tube having a diameter in a nanometer region, and a multi-walled carbon nanotube in which the graphene sheet is a multi-walled layer. Therefore, the diameter of the multi-walled carbon nanotube shows a large value of 30 nm with respect to 0.7-2.0 nm of a typical single-walled carbon nanotube.

Examples of commercially available conductive carbon fibers and carbon nanotubes include vapor-phase carbon fibers such as VGCF manufactured by Showa Denko Co., Ltd., EC1.0, EC1.5, EC2.0, EC1.5-P manufactured by Meijo Nanocarbon Co., Ltd., etc. Examples thereof include single-walled carbon nanotubes manufactured by CNano, FloTube9000, FloTube9100, FloTube9110, FloTube9200, NC7000 manufactured by Nanocyl, and 100T manufactured by Knano.

(Binder (B))
The type of the binder (B) can impart the dispersibility of the conductive carbon material (A), the adhesion to the non-conductive substrate, the flexibility of the conductive substrate, and the stability of the conductive composition. If this is the case, the present invention is not particularly limited, and examples thereof include resin and the like.

The binder (B) includes a polyurethane resin, a polyamide resin, an acrylonitrile resin, an acrylic resin, a butadiene resin, a polyvinyl resin, a polyvinyl butyral resin, a polyolefin resin, a polyester resin, a polystyrene resin, and an EVA resin. It can contain one or more kinds selected from the group consisting of resins, polyvinylidene fluoride-based resins, polytetrafluoroethylene-based resins, silicone-based resins, polyether-based resins, cellulose-based resins such as carboxymethyl cellulose, and the like. However, it is not limited to these resins. The binder resin may be used alone or in combination of two or more.

As the binder resin, a curable resin that undergoes a curing (crosslinking) reaction after the binder resin is applied to the substrate can also be used.
As the binder resin, a soluble resin or dispersed resin fine particles that are soluble in an aqueous or non-aqueous solvent can also be used. Dispersed resin fine particles exist in the state of fine particles without dissolving the resin fine particles in an aqueous or non-aqueous dispersion medium, and the dispersion is also generally called an emulsion. These may be used alone or in combination of two or more.

The particle structure of the dispersed resin fine particles may be a multilayer structure, so-called core-shell particles. For example, by localizing a resin obtained by mainly polymerizing a monomer having a can response period in the core portion or the shell portion, or by providing a difference in Tg and composition between the core and the shell, the curability and drying can be achieved. It is possible to improve the property, film forming property, and mechanical strength of the binder.
The average particle size of the resin fine particles is preferably 10 to 1000 nm, preferably 10 to 300 nm, from the viewpoint of binding properties and particle stability. The average particle size in the present invention represents a volume average particle size and can be measured by a dynamic light scattering method.
The average particle size can be measured by the dynamic light scattering method as follows. Dilute 200 to 1000 times with the same dispersion as the dispersion medium, depending on the solid content of the resin fine particles. Approximately 5 ml of the diluted dispersion is injected into a cell of a measuring device (Nikkiso Co., Ltd. name black truck), and the dispersion medium and the refractive index conditions of the resin corresponding to the sample are input, and then the measurement is performed. It can be measured by the peak of the volume particle size distribution data (histogram) obtained at this time.
In addition, enzymes such as glucose oxidase (GOx) often carry those dispersed in an aqueous solution, and fuels such as glucose are often dissolved in an aqueous solvent, so that they are wet and permeable. From the viewpoint of the above, the binder (B) is a water-soluble resin (BA) that is soluble in an aqueous solvent or water-dispersed resin fine particles (B-) that exist in the state of fine particles without being dissolved in an aqueous dispersion medium. It is preferable to use b).

Examples of the water-soluble resin include polyvinyl-based resins, polyurethane-based resins, polyester-based resins, polyether-based resins, cellulose-based resins such as carboxymethyl cellulose, formalin condensates, silicone-based resins, and composite resins thereof. Can be mentioned. Further, these two or more types may be used in combination.

Examples of the water-dispersed resin fine particles include (meth) acrylic emulsion, nitrile emulsion, urethane emulsion, polyolefin emulsion, fluorine emulsion (polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), etc.), and styrene-butadiene. Examples include system resins.
In addition, (meth) acrylic means methacrylic or acrylic.

From the viewpoint of slurry stability and coatability of the conductive composition, water resistance and flexibility of the conductive layer, the water-soluble resin (BA) and the water-dispersed resin fine particles (Bb) may be used in combination. More preferred.

(Solvent (dispersion medium))
When the conductive carbon material (A) and the binder (B) are uniformly mixed, a solvent can be appropriately used. The solvent is not particularly limited as long as it can dissolve the resin or stably disperse the resin fine particle emulsion, and examples thereof include water and organic solvents.

Organic solvents include alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol methyl ether and diethylene glycol methyl ether, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether and the like. Suitable for the composition of the conductive composition from among ethers, hydrocarbons such as hexane, heptane and octane, aromatics such as benzene, toluene, xylene and cumene, and esters such as ethyl acetate and butyl acetate. Can be used.
Further, as the solvent, water and an organic solvent or two or more kinds of organic solvents may be used.

Further, the conductive composition used in the present invention contains, if necessary, an ultraviolet absorber, an ultraviolet stabilizer, a radical catching agent, a filler, a thixotropic agent, and an antistatic agent as long as the effects of the present invention are not impaired. , Antioxidant, Antistatic, Flame Retardant, Thermal Conductivity Improver, Plasticizer, Anti-Dripping Agent, Antifouling Agent, Preservative, Bactericidal Agent, Defoamer, Leveling Agent, Anti-blocking Agent, Hardener, Increase Various additives such as a thickener, a pigment dispersant, and a silane coupling agent may be added.

(Conductive composition)
The conductive composition contains a conductive carbon material (A), a binder (B), and a solvent (dispersion medium) as necessary, and is made into a slurry (paint or ink) using a disperser or a mixer. It was done.

The viscosity of the conductive composition depends on the coating method of the conductive composition, but is generally preferably 10 mPa · s or more and 30,000 mPa · s or less.

(Disperser / Mixer)
As an apparatus used for obtaining a conductive composition, a disperser or a mixer usually used for pigment dispersion or the like can be used.

For example, mixers such as disper, homomixer, or planetary mixer; homogenizers such as "Clairemix" manufactured by M-Technique or "Philmix" manufactured by PRIMIX; paint conditioner (manufactured by Red Devil), ball mill, sand mill. Media type disperser such as (Symmal Enterprises "Dyno Mill" etc.), Atreiter, Pearl Mill (Eirich "DCP Mill" etc.), or Coball Mill; Wet Jet Mill (Genus PY "Genus PY", Sugino Medialess disperser such as "Starburst" manufactured by Machine Co., "Nanomizer" manufactured by Nanomizer, "Claire SS-5" manufactured by M-Technique, or "MICROS" manufactured by Nara Machinery; or other roll mills, etc. However, it is not limited to these.

For example, when using a media-type disperser, a method in which the agitator and vessel use a disperser made of ceramic or resin, or a disperser in which the surface of the metal agitator and vessel is treated with tungsten carbide spraying or resin coating. It is preferable to use. As the medium, it is preferable to use glass beads, zirconia beads, or ceramic beads such as alumina beads. As the dispersive device, only one type may be used, or a plurality of types of devices may be used in combination.

(Non-conductive substrate)
The properties of the base material are not particularly limited, and may be a natural material or a synthetic material. From the viewpoint of compatibility with the environment and living organisms, paper, non-woven fabric, cloth and the like using natural or biodegradable materials are preferable, and by selecting a flexible base material, it is suitable for wearable applications. In addition to the above, resin substrates such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), polyimide, polyvinyl chloride, polyamide, nylon, OPP (stretched polypropylene), and CPP (unstretched polypropylene) may be used. .. The thickness of the base material is not particularly limited and can be selected according to the shape of the enzyme power generation device and the like.

(Conductive layer)
A conductive layer can be formed by applying the conductive composition to the non-conductive base material and, if necessary, performing a press treatment or the like.
The method for coating the conductive composition on the non-conductive substrate is not particularly limited, and a known method can be used.

Specific examples include a die coating method, a dip coating method, a roll coating method, a doctor coating method, a knife coating method, a spray coating method, a gravure coating method, a screen printing method, an electrostatic coating method, and the like, and drying. As the method, a stand-alone dryer, a blower dryer, a warm air dryer, an infrared heater, a far infrared heater, and the like can be used, but the method is not particularly limited thereto.

Further, after coating, rolling processing may be performed by a lithographic press, a calendar roll, or the like, or may be performed while heating in order to soften the conductive layer and facilitate pressing. The thickness of the conductive layer is generally 0.1 μm or more and 1 mm or less, preferably 1 μm or more and 200 μm or less.

(Density of conductive layer)
The density of the conductive layer used in the present invention is 0.9 to 2.2 g / cm ³ , preferably 1.1 to 2.1 g / cm ³ , and more preferably 1.2 to 2.0 g / cm. It is ³ . If the density of the conductive layer is low, the contact between the conductive carbon materials in the conductive layer becomes insufficient, resulting in poor conductivity. On the other hand, if the density of the conductive layer is too high, the impregnation property of the electrolyte may deteriorate and the permeability of the proton (H ⁺ ) may deteriorate, which is not preferable.

(Volume resistivity of conductive layer)
The volume resistivity of the conductive layer used in the present invention is preferably 1 × 10 − ² Ω · cm or less. Since the volume resistivity is 1 × 10 ⁻² Ω · cm or less, it can be suitably used as a conductive substrate.

(Composition of conductive layer)
The ratio of the conductive carbon material (A) contained in the conductive layer used in the present invention is 50 to 90 mass with respect to the total solid content of the conductive layer due to the conductivity and adhesion to the non-conductive substrate. % Is preferable, and 60 to 80% by mass is more preferable. The component other than the conductive carbon material (A) is mainly the binder (B), but any other component may be contained. From the viewpoint of conductivity and adhesion, the total ratio of the conductive carbon material (A) and the binder resin (B) to the total solid content in the conductive layer is preferably 5 to 50% by mass, more preferably. Is 10 to 40% by mass.

<Enzyme power generation device>
The enzyme power generation device can generate power by using an organic substance such as sugar or alcohol as a fuel and utilizing the oxygen reduction reaction on the cathode side by e- ⁽ electrons) and ions generated at the anode. In addition, it is possible to sense an object (fuel) by detecting the presence or absence of power generation and the amount of power generation, and it can function as a sensor that also serves as a power source and a sensor. The power generation type sensor having the above-mentioned function is included in a kind of enzyme power generation device. The configuration of the enzyme power generation device includes an anode that oxidizes fuel, a cathode that undergoes oxygen reduction, and a separator that separates the anode and cathode. However, the separator may not be necessary as long as the anode and cathode can be electrically separated.

The conductive base material in the present invention can be used as a conductive base material or a conductive support for a cathode electrode or an anode electrode.
Further, an ion conductor for transferring ions from the anode to the cathode side may be included. Considering compactness, weight reduction, storage stability, etc., it may be preferable to use an ionic conductor contained in urine, sweat, blood, etc., which are fuels (sensing objects).

(fuel)
The type of fuel that can be used in the enzyme power generation device is not particularly limited as long as it is a substance whose oxidation is promoted by the enzyme. Examples thereof include monosaccharides such as D-glucose, polysaccharides such as starch, alcohols such as ethanol, and organic substances such as organic acids, and may be used alone or in combination of two or more. The fuel may be in an oxidizable state by an enzyme contained in the anode as it is, or may be in an oxidizable state by hydrolysis or the like.
When used as a wearable device, a disposable device, or the like, the fuel preferably contains sugar from the viewpoint of safety and biocompatibility. The type of sugar is not particularly limited, and examples thereof include monosaccharides, disaccharides, oligosaccharides, polysaccharides, and sugar alcohol sugars.

(Cathode electrode)
The cathode electrode of the enzyme power generation device preferably contains a catalyst that promotes the reduction of oxygen on the conductive substrate of the present invention. The type of catalyst is not particularly limited and may be organic or inorganic. Examples of the organic substance include enzymes that promote the reduction of enzymes such as bilirubin oxidase and laccase. Examples of the inorganic substance include a metal catalyst such as platinum and a carbon alloy catalyst. Organic substances and carbon alloy catalysts are preferable from the viewpoint of disposable use and biocompatibility, and carbon alloy catalysts are more preferable from the viewpoint of cost and output stability.
When an enzyme is used as a catalyst, carbon black (Ketjen black, acetylene black, etc.), mesoporous carbon, carbon nanotubes, etc. may be coated on the conductive substrate of the present invention in order to support the enzyme. The enzyme may be supported on a conductive substrate.
In addition, a mediator may be included if necessary, such as the type of enzyme.

The method of supporting the enzyme or the mediator may be carried out by including it in the above-mentioned composition for forming a positive electrode, or may be carried out later on a coating film dried after coating or a conductive support. In the case of performing it later, a method of immersing a liquid in which an enzyme or a mediator is dissolved in the above-mentioned coating film or a conductive support, and then drying and supporting the solution can be used.

(Electrode for anode)
The anode electrode of the enzyme power generation device preferably contains an enzyme that promotes oxidation of the fuel on the conductive substrate of the present invention. The type of enzyme is not particularly limited and can be selected according to the type of fuel to be oxidized, and may be one type or two or more types.
Further, in order to carry an enzyme, carbon having a large specific surface area such as carbon black (Ketjen black, acetylene black, etc.) and carbon nanotubes, and porous carbon having micro to mesopores such as mesoporous carbon are conductive in the present invention. It may be contained on a sex substrate.
Similar to the cathode electrode, a mediator may be included, and the support can be performed in the same manner.

(Mediator)
Depending on the type of enzyme, there are direct electron transfer type (DET type) enzymes that can directly transfer electrons to the electrode and enzymes that cannot directly transfer electrons. Enzymes other than the DET type can be used in combination with a mediator that is responsible for transferring the electrons generated by the oxidation of the fuel from the enzyme to the electrode (anode) or the electrons received from the anode from the electrode (cathode) to the enzyme. preferable. The mediator is not particularly limited as long as it is a redox substance capable of exchanging electrons with the electrode, and conventionally known mediators can be used.

(Conductive support)
The conductive support is used for transferring electrons generated at the anode to the cathode and for extracting electricity generated by the battery reaction, and is not particularly limited as long as it is a conductive material. When used as a wearable device, disposable device, etc., the conductive substrate of the present invention may be used as it is from the viewpoint of safety, biocompatibility, easy disposal, etc., and carbon paper, carbon felt, carbon cloth, etc. may be used. You may.

(Separator)
A separator capable of electrically separating the anode and the cathode (preventing a short circuit) can be used as needed. The separator is not particularly limited, and conventionally known materials can be used. Specifically, polyethylene fiber, polypropylene fiber, glass fiber, resin non-woven fabric, glass non-woven fabric, filter paper, Japanese paper and the like can be used.

(Ion conductor)
The ion conductor in the present invention conducts ions between the anode and the cathode. The form of the ionic conductor is not particularly limited as long as it has ionic conductivity. As the ionic conductor, for example, an electrolytic solution in which an electrolyte is dissolved in a liquid such as a phosphate buffer solution, a solid polymer electrolyte, or the like may be used.

Hereinafter, the present invention will be described in more detail by way of examples, but the following examples do not limit the scope of rights of the present invention in any way.

<Preparation of conductive composition>
(Manufacturing Example 1)
To 200 parts by mass of ion-exchanged water, 2 parts by mass of the water-soluble resin (B-1) was added and dissolved with stirring with a disper. Then, 95 parts by mass of the conductive carbon material (A-1) was added. Then, dispersion was performed with a sand mill.
Next, 6 parts by mass of water-dispersed resin fine particles (B-4: 50% by mass) were added and mixed with a disper to obtain the conductive composition (1) shown in Table 1.

(Manufacturing Example 2)
To 200 parts by mass of ion-exchanged water, 2 parts by mass of the water-soluble resin (B-1) was added and dissolved with stirring with a disper. Then, 95 parts by mass of the conductive carbon material (A-1) was added. Then, dispersion was performed with a disper.

Next, 6 parts by mass of water-dispersed resin fine particles (B-4: 50% by mass) were added and mixed with a disper to obtain the conductive composition (2) shown in Table 1.
(Conductive compositions (3) to (5), (7) to (9))
The conductive compositions (3) to (5) and (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) to (7) 9) was obtained.

(Conductive composition (6))
The conductive composition (6) was obtained by the same method as that of the conductive composition (2) (Production Example 2) except that the composition ratio and the material shown in Table 1 were changed.

The material used in the production example of the conductive composition and the method of dispersing the conductive carbon material (A) are shown below.
(Conductive carbon material (A))
Graphite (AA)
-A-1: Spheroidized graphite CGB-50 (manufactured by Nippon Graphite Co., Ltd.)
-A-2: Scaled graphite CB-150 (manufactured by Nippon Graphite Co., Ltd.)
・ A-3: Thinned graphite UP-20 (manufactured by Nippon Graphite Co., Ltd.)
Carbon materials other than graphite (Ab)
・ A-4: Lionite EC-200L (manufactured by Lion)
(Binder (B))
Water-soluble resin (BA)
B-1: CMC Daicel # 1240 (manufactured by Daicel Chemical Industries, Ltd.)
・ B-2: Kuraray Poval PVA235 (manufactured by Kuraray)
Water-insoluble resin B-3: KF polymer # 9100 (manufactured by Kureha Corporation)
Water-dispersed resin fine particles (Bb)
B-4: Acrylic resin aqueous dispersion W-168 (solid content 50% by mass manufactured by Toyochem Co., Ltd.)
Dispersion method of conductive carbon material (A) ・ D-1: Sandmill ・ D-2: Disper

<Manufacturing of conductive base material>
(Example 1)
A qualitative filter paper (manufactured by No. 5C ADVANTEC) was roll-pressed at room temperature, and a filter paper having a thickness of about 140 μm was used as a non-conductive base material.
The conductive composition (1) was applied onto the non-conductive substrate using a doctor blade and then dried by heating to obtain a conductive substrate.
Table 2 shows the evaluation results of the obtained conductive base material (conductive layer) and electrodes.

(Density of conductive layer)
The density of the conductive layer was evaluated from the mass and volume of the conductive layer. Specifically, the mass and thickness of a 10 cm square conductive base material (area: 100 cm ² ) in which a conductive layer is formed on a non-conductive base material, and a 10 cm square non-conductive base material (area: 100 cm ² ). The mass and thickness of the 10 cm square conductive layer (area: 100 cm ² ) were measured and the mass and thickness were calculated. Next, the density of the conductive layer was calculated by dividing the mass of the conductive layer by the volume (area × thickness). The evaluation results are shown in Table 2.

(Resistivity of conductive layer)
The volume resistivity of the conductive layer was determined by measurement (JIS-K7194) by the 4-terminal method using Loresta GP (manufactured by Mitsubishi Chemical Analytech Co., Ltd.). The evaluation results are shown in Table 2.
⊚: "Volume resistivity is less than 5 x 10 ^-3 Ω · cm (extremely good)"
〇: “Volume resistivity is 5 × 10 ^-3 Ω ・ cm or more and 1 × 10 ^-2 Ω ・ cm or less (good)”
〇 △: "Volume resistivity is 1 x 10 ^-2 Ω · cm or more and 5 x 10 ^-2 Ω · cm or less (usable)"
Δ: “Volume resistivity is 5 × 10 ⁻² Ω · cm or more and 1 × 10 ^-1 Ω · cm or less (defective)”
×: “Volume resistivity is 1 × 10 ^-1 Ω · cm or more (extremely defective)”

(Bending characteristics of conductive substrate)
The conductive current collector was bent to an angle of 45 °, and the presence or absence of cracks was confirmed. The evaluation results are shown in Table 2.
〇: Does not break (good)
×: Cracked (defective)

(Examples 4 to 6, Example 9, Comparative Examples 1 to 3)
Conductive substrates (4) to (6), (9), (11) to (13) of Examples, respectively, by the same method as in Example 1 except that the conductive composition shown in Table 2 was changed. Got

(Example 2)
A qualitative filter paper (manufactured by No. 5C ADVANTEC) was roll-pressed at room temperature, and a filter paper having a thickness of about 140 μm was used as a non-conductive base material.
The conductive composition (1) was applied onto the non-conductive substrate using a doctor blade, and then heat-dried. Then, a roll press was performed to obtain a conductive substrate (2).

(Example 3, Examples 7 to 8, Example 10)
The conductive substrates (3), (7), (8), and (10) of Examples were obtained by the same method as in Example 2 except that the conductive composition shown in Table 2 was changed.

(Comparative Example 4)
Instead of the conductive base material of the present invention, carbon paper (manufactured by Toray Industries, Inc.) was used to prepare the conductive base material (14).

<Manufacturing of electrodes for anodes>
(Examples 1 to 10, Comparative Examples 1 to 4)
20 parts by mass of a water-soluble resin (B-2: Kuraray Poval PVA235 (manufactured by Kuraray Co., Ltd.)) is added to 400 parts by mass of ion-exchanged water while stirring with a disper to dissolve it, and then a conductive carbon material (A-4). : Lionite EC-200L) 60 parts by mass was added. Then, dispersion was performed with a sand mill. Next, 40 parts by mass of water-dispersed resin fine particles (B-4: acrylic resin water dispersion W-168 (solid content 50% by mass, manufactured by Toyochem)) was added and mixed with a disper to obtain a paste for an anode electrode. ..
The conductive substrate ((1) to (14)) is cut into 1 × 3 cm (area: 3 cm ² ), and then 1 × 2 cm (area: 2 cm ² ) is masked with tape and then masked. The paste for the anode electrode was applied to a 1 × 1 cm (area: 1 cm ² ) portion on the untreated conductive substrate using a doctor blade, dried by heating, and then the masking tape was peeled off. The 1 × 1 cm portion coated with the anode electrode paste was used as an electrode, and the uncoated 1 × 2 cm portion was used as a conductive support. Then, a saturated methanol solution of tetrathiafulvalene and an aqueous glucose oxidase solution were added dropwise and air-dried to obtain electrodes (1) to (14) for the anode.

<Electrochemical enzyme activity evaluation (power generation characteristics)>
(Linear sweep voltammetry (LSV) measurement)
0.1M phosphate buffer (pH 7.0) as an electrolytic solution (ion conductor) in the electrolytic tank to which the prepared electrode for anode, counter electrode (platinum coil electrode), and reference electrode (silver / silver chloride electrode) are attached. ) Is added, D-glucose is added as a reaction substrate (sensing object) so as to be 0.1 M, and LSV measurement is performed in the range of -0.2 V (vsAg / AgCl) to +0.5 V (vsAg / AgCl). I did it. (LSV measurement was performed under the same conditions without adding D-glucose to the electrolytic solution, and background correction was performed.)

From the background-corrected reduction current curve obtained from the LSV measurement, the maximum value of the reduction current density (mA / cm ² ) was evaluated using the following criteria as an index. The evaluation results are shown in Table 3.
(Reducing activity of enzyme)
⊚: “Glucose oxidation active current density is 10 mA / cm ² or more (extremely good)”
〇: "Glucose oxidation active current density is 5 mA / cm ² or more and less than 10 mA / cm ² (good)"
Δ: “Glucose oxidation active current density is 3 mA / cm ² or more and less than 5 mA / cm ² (usable)”
×; “Glucose oxidation active current density is less than 3 mA / cm ² (defective)”

As shown in Tables 2 and 3, it was confirmed that in the conductive substrate of the present invention, as a result of improving the conductivity, the reducing activity of the enzyme on the anode side was greatly improved. It is considered that the enzyme reaction does not become rate-determining because the electrons taken out by the oxidation of the fuel move smoothly due to the improvement of the conductivity of the conductive base material.
On the other hand, in Comparative Examples 1 to 3, it is assumed that the above reaction does not occur smoothly and the power generation characteristics are deteriorated because the conductivity is not insufficient. Further, although the carbon paper of Comparative Example 4 exhibits good power generation characteristics, it is not considered to be suitable because its flexibility is not sufficient and its use in wearable devices and the like is greatly restricted.

The conductive substrate described in the present invention can be similarly used for a cathode electrode. Further, by combining the electrode for the anode and the electrode for the cathode using the conductive substrate of the present invention, it can be used as an enzyme power generation device and also as a self-power generation sensor capable of detecting an object to be fuel. Furthermore, by incorporating the fuel inside the enzyme power generation device, it can also be used as a moisture sensor.

Claims (8)

A conductive substrate for an enzyme power generation device having a non-conductive substrate and a conductive layer arranged on the non-conductive substrate, wherein the conductive layer is a conductive carbon material (A) and a binder (B). ) And
The density of the conductive layer is 0.9 to 2.2 g / cm ³ .
Conductive substrate for enzyme power generation devices. The conductive substrate for an enzyme power generation device according to claim 1, wherein the volume resistivity of the conductive layer is 1 × 10 − ² Ω · cm or less. The conductive substrate for an enzyme power generation device according to claim 1 or 2, wherein the binder (B) contains a water-soluble resin (Ba) or water-dispersed resin fine particles (Bb). The conductive substrate for an enzyme power generation device according to any one of claims 1 to 3, wherein the conductive carbon material (A) contains at least graphite (AA). The content of the carbon material (A) in the total solid content of the conductive layer of 100% by mass is 50 to 90% by mass, and the mass ratio (Aa) of the graphite (Aa) contained in the carbon material (A) is (Aa). ) / (A) × 100 is 25 to 100% by mass, according to any one of claims 1 to 4. The conductive substrate for an enzyme power generation device. The conductive substrate for an enzyme power generation device according to any one of claims 1 to 5, wherein the content of the binder (B) in the total solid content of the conductive layer is 5 to 50% by mass. .. An electrode for an enzyme power generation device, wherein the conductive substrate according to any one of claims 1 to 6 is used for the anode and the cathode. An enzyme power generation device formed by using the electrodes for the enzyme power generation device according to claim 7 as an anode and a cathode.