JP2013084363A - Bio fuel cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bio fuel cell module which can be utilized for a long period of time and easily supplied with fuel.SOLUTION: A bio fuel cell module is fabricated by laminating a plurality of plate-like or sheet-like fuel cells having one or more power generation parts provided with an electrode with a redox enzyme existing on the surface thereof, making uniform the positions of their fuel supply parts. This bio fuel cell module makes it possible to supply fuel to all of fuel cells or any number of fuel cells. Moreover, it is also possible to allow an electrode part provided in the power generation part of each fuel cell to be replaceable.

Description

  The present technology relates to a biofuel cell module including a fuel cell using an oxidoreductase. More specifically, the present invention relates to a biofuel cell module in which a plurality of fuel cells are stacked.

  In recent years, a fuel cell (hereinafter referred to as a biofuel cell) in which an oxidoreductase is immobilized as a reaction catalyst on at least one of an anode and a cathode attracts attention. This biofuel cell is expected to be a next-generation fuel cell with high capacity and high safety because it can efficiently extract electrons from fuels that are difficult to react with ordinary industrial catalysts such as glucose and ethanol. Has been.

FIG. 10 is a diagram schematically showing the power generation principle of a biofuel cell using an enzyme. For example, in the case of a biofuel cell using glucose as a fuel as shown in FIG. 10, the negative electrode (anode) 101 decomposes glucose (Glucose) with an enzyme immobilized on the surface to take out electrons (e ⁻ ). Proton (H ⁺ ) is generated. In the positive electrode (cathode) 102, protons (H ⁺ ) transported from the negative electrode (anode) 101 through the proton conductor 103, electrons (e ⁻ ) sent through an external circuit, and air, for example, Water (H ₂ O) is produced by oxygen (O ₂ ) in the medium. And the reaction of these positive / negative electrodes occurs simultaneously, and an electrical energy generate | occur | produces between positive / negative electrodes.

  On the other hand, the direct methanol type fuel cell has a problem that the voltage of a single cell is low. For this reason, the conventional fuel cell is generally used in the form of a module in which a plurality of cells are connected in series (see, for example, Patent Documents 1 to 3). For example, in the vehicle fuel cell reuse system described in Patent Document 3, output adjustment is performed according to the intended use by extracting a partial stack from a fuel cell in which a plurality of cells are stacked. Conventionally, a biofuel cell has also been proposed with a structure in which a plurality of cells are connected in parallel and / or in series for the purpose of improving output (see, for example, Patent Documents 4 and 5).

JP 2006-139985 A JP 2007-149432 A JP 2010-27240 A JP 2009-140646 A JP 2009-48848 A

  However, the conventional fuel cell described above has the following problems. In general, in a biofuel cell, fuel is injected at the time of use. However, in the case of a fuel cell in which a plurality of cells are connected in series, the fuel must be individually injected into each cell, and the work is complicated. There is a point. On the other hand, the power supply device described in Patent Document 4 uses the air layer as an ion blocker after supplying fuel so that fuel can be supplied to a plurality of cells simultaneously. Is necessary and takes time.

  In addition, the conventional biofuel cell has a problem that the power generation performance is lowered in a few days to several weeks from the start of use due to limitations such as enzyme stability during power generation and elution of electron transfer materials.

  Therefore, the main object of the present disclosure is to provide a biofuel cell module that can be used for a long period of time and can be easily supplied with fuel.

In the biofuel cell module according to the present disclosure, a flat or sheet-like fuel cell having one or more power generation units provided with electrodes on the surface of which an oxidoreductase is present is aligned in the position of the fuel supply unit. Are stacked.
In this biofuel cell, the fuel can be supplied only to the uppermost or lowermost fuel cell.
Each fuel cell may be removable or replaceable.
Furthermore, a plurality of fuel cells may be stacked by providing a plurality of fuel cells on one plate or sheet, and forming cuts or folds between the fuel cells, and folding the cuts or folds.
In that case, each fuel cell can be made detachable by the cut or crease.
Furthermore, the power generation unit of each fuel cell is provided with a pair of electrodes constituting an anode or a cathode and a separator disposed between the electrodes to prevent a short circuit. Each electrode and / or separator is exchanged. It can also be possible.

  According to the present disclosure, since a plurality of fuel cells are stacked with the positions of the fuel supply portions thereof aligned, fuel supply is facilitated, and long-term use is also possible.

(A) is a side view which shows typically the structure of the biofuel cell module of 1st Embodiment of this indication, (b) is a figure which shows the usage method. It is a figure which shows typically the structure of the fuel cell 1 shown in FIG. (A) And (b) is sectional drawing which shows typically the fuel supply method in the biofuel cell module 10 shown in FIG. 2 is a diagram illustrating a configuration example of an electrode portion of the fuel cell 1. FIG. It is a figure which shows typically the method of replacing | exchanging the electrode part shown in FIG. It is sectional drawing which shows typically the fuel supply method of the fuel cell 1 provided with a heat retention tank. (A) And (b) is a figure which shows the battery replacement | exchange method in the biofuel cell module of the 1st modification of the 1st Embodiment of this indication. (A)-(c) is a figure showing a battery exchange method in a biofuel cell module of the 2nd modification of a 1st embodiment of this indication. It is a side view showing typically composition of a biofuel cell module of a 2nd embodiment of this indication. It is a figure which shows typically the electric power generation principle of the biofuel cell which uses an enzyme.

Hereinafter, modes for carrying out the present disclosure will be described in detail with reference to the accompanying drawings. In addition, this indication is not limited to each embodiment shown below. The description will be given in the following order.

1. First Embodiment (Example of biofuel cell module in which a plurality of fuel cells are stacked)
2. First Modification of First Embodiment (Example in which a fuel cell is replaced by opening a current collector)
3. Second Modification of First Embodiment (Example in which used fuel cell is bent and taken out)
4). Second Embodiment (Example of biofuel cell module in which fuel cells are stacked by folding)

<1. First Embodiment>
[overall structure]
First, the biofuel cell module according to the first embodiment of the present disclosure will be described. FIG. 1A is a side view schematically illustrating the configuration of the biofuel cell module according to the first embodiment of the present disclosure, and FIG. 1B is a diagram illustrating a method of using the same. As shown in FIG. 1 (a), the biofuel cell module 10 of the present embodiment has a flat or sheet-like fuel cell 1 having one or more power generation units, with the positions of the fuel supply units aligned. It has a laminated structure.

[Fuel cell 1]
FIG. 2 is a diagram schematically showing the configuration of the fuel cell 1 shown in FIG. As shown in FIG. 2, the fuel cell 1 is provided with an anode 11 and a cathode 13, and a separator 12 is disposed between them. A fuel diffusion layer 15 and an anode sealing material 17 are provided outside the anode 11, and a fuel liquid reservoir 19 having a lid 14 is formed at the center of the anode sealing material 17. Yes.

  On the other hand, a cathode sealing material 18 is provided outside the cathode 13. The portion of the cathode sealing material 18 that comes into contact with the cathode 13 is formed by the oxygen permeable film 16, and oxygen is supplied to the cathode 13. Furthermore, an anode terminal 20 and a cathode terminal 21 are connected to the anode 11 and the cathode 13, respectively.

  In the biofuel cell 1, oxidoreductase is present on the electrode surface of the anode 11 or the cathode 13 or both. Here, the surface of the electrode includes the entire outer surface of the electrode and the inner surface of the void inside the electrode, and the same applies to the following description.

(Anode 11)
The anode 11 is a fuel electrode, and for example, an anode in which an oxidoreductase is immobilized on the surface of an electrode made of a conductive porous material can be used. As the conductive porous material used in this case, known materials can be used, and in particular, carbon-based materials such as porous carbon, carbon pellets, carbon felt, carbon paper, carbon fiber, or a laminate of carbon fine particles. Material is preferred.

  As the enzyme immobilized on the surface of the anode 11, for example, when the fuel component is glucose, glucose dehydrogenase (GDH) that decomposes glucose can be used. Furthermore, when a monosaccharide such as glucose is used as a fuel component, a coenzyme oxidase and an electron mediator are immobilized on the anode surface together with an oxidase that promotes and decomposes monosaccharide such as GDH. It is desirable.

The coenzyme oxidase oxidizes a coenzyme (eg, NAD ⁺ , NADP ^+, etc.) reduced by an oxidase and a coenzyme reductant (eg, NADH, NADPH, etc.), such as diaphorase, etc. Is mentioned. By the action of the coenzyme oxidase, electrons are generated when the coenzyme returns to the oxidized form, and the electrons are transferred from the coenzyme oxidase to the electrode via the electron mediator.

  As the electron mediator, a compound having a quinone skeleton is preferably used, and a compound having a naphthoquinone skeleton is particularly preferable. Specifically, 2-amino-1,4-naphthoquinone (ANQ), 2-amino-3-methyl-1,4-naphthoquinone (AMNQ), 2-methyl-1,4-naphthoquinone (VK3), 2- Amino-3-carboxy-1,4-naphthoquinone (ACNQ) and the like can be used.

  In addition to compounds having a naphthoquinone skeleton, compounds having a quinone skeleton include compounds having an anthraquinone skeleton such as anthraquinone-1-sulfonic acid, anthraquinone-2-sulfonic acid and anthraquinone-2-carboxylic acid, and derivatives thereof. Can also be used. Furthermore, you may fix | immobilize the 1 type, or 2 or more types of other compound which acts as an electron mediator with the compound which has quinone skeleton as needed.

  On the other hand, when a polysaccharide is used as the fuel component, in addition to the oxidase, coenzyme oxidase, coenzyme and electron mediator described above, the hydrolysis of the polysaccharide is promoted to decompose, and a monosaccharide such as glucose is added. It is desirable that the degradation enzyme to be produced is immobilized. The term “polysaccharide” as used herein refers to a polysaccharide in a broad sense and refers to all carbohydrates that produce two or more monosaccharides by hydrolysis, and includes oligosaccharides such as disaccharides, trisaccharides, and tetrasaccharides. Specific examples include starch, amylose, amylopectin, glycogen, cellulose, maltose, sucrose, and lactose. These are a combination of two or more monosaccharides, and any polysaccharide contains glucose as a monosaccharide of the binding unit.

  Amylose and amylopectin are components contained in starch, and starch is a mixture of amylose and amylopectin. For example, when glucoamylase is used as a polysaccharide degrading enzyme and glucose dehydrogenase is used as an oxidase degrading monosaccharide, a polysaccharide that can be decomposed into glucose by glucoamylase is used as the fuel component. can do.

  Examples of such polysaccharides include starch, amylose, amylopectin, glycogen and maltose. Here, glucoamylase is a degrading enzyme that hydrolyzes α-glucan such as starch to produce glucose, and glucose dehydrogenase is an oxidase that oxidizes β-D-glucose to D-glucono-δ-lactone. .

  The anode 11 is not limited to the one having the oxidoreductase immobilized on the surface. For example, if the oxidoreductase is present on the electrode surface, the anode 11 has an oxidoreductase, for example. It is also possible to use an electrode to which microorganisms acting as a reaction catalyst are attached.

(Cathode 13)
The cathode 13 is an air electrode and is in contact with the gas phase (air) through the gas-liquid separation film 16. The electrode constituting the cathode 13 is not particularly limited. For example, an electrode in which an oxidoreductase and an electron mediator are immobilized on the surface of an electrode made of a conductive porous material can be used. . As the conductive porous material forming the cathode 13, known materials can be used, and in particular, carbon-based materials such as porous carbon, carbon pellets, carbon felt, carbon paper, carbon fiber, or a laminate of carbon fine particles. Material is preferred.

  Examples of the oxygen reductase immobilized on the cathode 13 include bilirubin oxidase, laccase, and ascorbate oxidase. Examples of the electron mediator immobilized together with these enzymes include potassium hexacyanoferrate (II), potassium hexacyanoferrate (III), potassium ferricyanide and potassium octacyanotungstate.

  The cathode 13 is not limited to the one having the oxidoreductase immobilized on the surface. For example, if the oxidoreductase is present on the electrode surface, the cathode 13 has, for example, an oxidoreductase. It is also possible to use an electrode to which microorganisms acting as a reaction catalyst are attached.

(Separator 12)
The separator 12 prevents a short circuit between the electrodes (the anode 11 and the cathode 13), and is formed of a material that has flexibility and transmits protons (proton conductor). Specifically, a nonwoven fabric, a cellophane, a perfluorosulfonic acid type ion exchange membrane etc. can be used, for example.

(Gas-liquid separation membrane 16)
The gas-liquid separation membrane 16 does not permeate liquid but permeates only gas. For example, a PTFE (PolyTetraFluoroEthylene: polytetrafluoroethylene) membrane or the like can be used. The thickness and physical properties are not particularly limited as long as the fuel solution can be prevented from leaking and oxygen necessary for the reaction can be supplied to the cathode 5.

(Seal materials 17, 18)
The anode sealing material 17 and the cathode sealing material 18 are for sealing the power generation section. For example, an ionomer film, a polyethylene film, a polyvinyl chloride film, a polyvinylidene chloride film, a polyvinyl alcohol film, a polypropylene film, a polyester film, A polycarbonate film, a polystyrene film, a polyacrylonitrile film, an ethylene-vinyl acetate copolymer film, an ethylene-vinyl alcohol copolymer film, an ethylene-methacrylic acid copolymer film, a nylon film, or cellophane can be used. Moreover, sealing and unsealing become easy by giving adhesiveness to the surface at the power generation part side of these sealing materials 17 and 18.

[Fuel supply method]
Next, a method for supplying fuel to each fuel cell 1 of the biofuel cell module 10 of the present embodiment will be described. 3A and 3B are cross-sectional views schematically showing a fuel supply method in the biofuel cell module 10 of the present embodiment. When a plurality of stacked fuel cells 1 are connected in series, it is necessary to supply fuel to all the fuel cells 1. In that case, for example, as shown in FIG. 3A, a through-hole serving as a fuel supply port / vent hole 2 is provided at a corresponding position of each fuel cell 1.

  Then, the fuel 4 is filled into the fuel supply port / vent 2. As a result, the fuel 4 is absorbed inside the battery by the capillary capacity. As a result, the fuel 4 can be easily supplied to all the fuel cells 1 by one operation. In addition, after all the fuel 4 is absorbed, air (oxygen) is supplied from the fuel supply port / vent 2, and thus power generation starts.

  The cathode 13 can be prevented from being submerged when the fuel 4 is supplied by subjecting the cathode 13 to water repellent processing. Further, in the structure shown in FIG. 3A, there is a possibility that the supply amount of oxygen may be insufficient depending on the output, but in that case, it penetrates in the thickness direction to a place other than the fuel supply port / vent 2. Alternatively, it is possible to increase the amount of oxygen shared by providing a plurality of vent holes.

  On the other hand, when the plurality of stacked fuel cells 1 are independent from each other, as shown in FIG. 3B, the amount of fuel 4 supplied is adjusted to adjust the amount of fuel 4 supplied. The number can be controlled. Thereby, an output can be arbitrarily set. Also, for example, first, the fuel 4 is supplied only to the lowermost fuel cell 1 to generate power, and when the performance deteriorates, the fuel 4 is supplied to the fuel cell 1 above to generate power. May be. In that case, the fuel cell 1 can also be supplied by removing the lowermost fuel cell 1 whose power generation performance has deteriorated and using the fuel cell 1 thereabove as the lowermost fuel cell 1.

  FIG. 3 shows an example in which the fuel cell 1 is provided with a through-hole serving as the fuel supply port / ventilation port 2, but the present disclosure is not limited to this, and a plurality of stacked fuel cells are provided. When 1 is independent, the fuel 4 can be supplied only to the uppermost fuel cell 1 to generate electric power. In that case, as shown in FIG. 1 (b), power is first generated in the uppermost fuel cell 1, and when the power generation performance deteriorates, the fuel cell 1 is removed, and the fuel cell 1 below it is removed. What is necessary is just to generate electricity.

  Here, the “fuel solution 4” supplied to each fuel cell 1 of the biofuel cell module 10 of the present embodiment is a fuel component such as sugar, alcohol, aldehyde, lipid and protein, or at least one of these fuel components. A solution containing Examples of the fuel component used in the fuel cell 1 include sugars such as glucose, fructose, and sorbose, alcohols such as methanol, ethanol, propanol, glycerin, and polyvinyl alcohol, aldehydes such as formaldehyde and acetaldehyde, acetic acid, Examples include organic acids such as formic acid and pyruvic acid. In addition, fats and proteins, organic acids that are intermediate products of these sugar metabolisms, and the like can be used as fuel components.

[Replacement of electrode part]
The biofuel cell module 10 of this embodiment can also be used by exchanging the electrode part of the fuel cell 1 having deteriorated power generation performance. FIG. 4 is a diagram showing a configuration example of the electrode portion of the fuel cell 1, and FIG. 5 is a diagram schematically showing a method of replacing the electrode portion shown in FIG. For example, as shown in FIG. 4, when the electrode part has a configuration in which the separator 12, the anode 11, and the cathode 13 are integrated, as shown in FIG. 5, the sealing member 17 or 18 is sealed by the opening / closing tab 22. The power generation performance can be easily recovered by releasing the stop and replacing the electrode part.

  The anode 11, the cathode 13, and the separator 12 do not necessarily have to be integrated, and they can be replaced separately. Moreover, it becomes possible to respond to various fuels by exchanging the anode 11 with a different immobilized enzyme.

[Heating of fuel 4]
In addition, the biofuel module 10 of the present embodiment can fill the fuel diffusion layer 15 and the fuel liquid reservoir 19 with a hydrous heat generating material such as calcium oxide. In this way, when the hydrous heat generating material is filled, the hydrous heat generating material generates an exothermic reaction due to moisture contained in the fuel 4 and the fuel 4 is heated. Therefore, the temperature in the power generation unit is easily increased to increase the output. be able to. As a result, for example, even when a cold beverage is used as the fuel 4 or when the outside air temperature is low, a high output can be stably obtained.

  Or you may provide the thermal insulation tank with which the hydrous heat generating material was filled in the fuel cell 1 separately. FIG. 6 is a cross-sectional view schematically showing a fuel supply method of the fuel cell 1 having a heat retaining tank. As shown in FIG. 6, when the heat retaining tank 23 is disposed in contact with the outside of the anode 11, the fuel 4 is absorbed by the heat retaining tank 23 and the anode 11 by the capillary capacity. Further, oxygen 5 is supplied to the cathode 13 from the fuel supply port / vent 2. Also in the fuel cell 1 configured to include the heat retaining tank 23, the fuel 4 can be heated and the temperature of the power generation unit can be increased by the exothermic reaction of the hydrous heat generating material.

  As described above in detail, the biofuel module 10 of the present embodiment has a structure in which a plurality of fuel cells 1 are stacked. Therefore, by sequentially using them according to the output, long-term power generation is possible. . Further, since the fuel supply ports of the fuel cells 1 are aligned, the fuel supply operation is easy, and the fuel can be supplied to a plurality of fuel cells 1 by a single operation.

  Furthermore, the biofuel module 10 of the present embodiment can recover the reduced power generation performance by making the electrode part of the fuel cell 1 and its constituent members replaceable. As a result, other members can continue to be used, so that cost performance is enhanced and waste is reduced, so that the environmental load can also be reduced. In addition, when used for a long period of time, it is only necessary to facilitate the replacement electrode portion, so there is no need to carry a plurality of batteries, and the mobility is improved. Furthermore, by exchanging different enzymes for the immobilized anode, various substances can be used as fuel.

<2. First Modification of First Embodiment>
FIG. 7A and FIG. 7B are diagrams illustrating a battery replacement method in the biofuel cell module according to the first modified example of the first embodiment of the present disclosure. In the first embodiment described above, the uppermost fuel cell 1 is peeled off and removed, but the present disclosure is not limited to this, and various forms can be applied.

  For example, in the case of the biofuel cell module of this modification, as shown in FIG. 7A, the current collector 3 is connected to the uppermost fuel cell 1a that generates power. When the power generation performance of the fuel cell 1a deteriorates, as shown in FIG. 7B, the current collector 3 is opened and the fuel cell 1a is removed. Thereafter, each fuel cell is pushed up, and the current collector 3 is attached to the fuel cell 1b which is the uppermost layer to generate power. As a result, the fuel cell can be easily replaced.

<3. Second Modification of First Embodiment>
FIGS. 8A to 8C are diagrams illustrating a battery replacement method in the biofuel cell module according to the second modified example of the first embodiment of the present disclosure. Further, for example, as shown in FIGS. 8A to 8C, the used fuel cell 1 a is pushed out by utilizing the flexibility of the fuel cell, and the unused fuel cell 1 b is connected to the current collector 3. It is good also as a structure which fits. Also in this case, the same effect as that of the biofuel cell module of the first embodiment described above can be obtained.

<4. Second Embodiment>
[overall structure]
Next, the biofuel cell module according to the second embodiment of the present disclosure will be described. FIG. 9 is a side view schematically showing the configuration of the biofuel cell module according to the second embodiment of the present disclosure. As shown in FIG. 9, the biofuel module 30 of the present embodiment is provided with a plurality of fuel cells 31 on one plate or sheet, and a cut 32 is formed between the fuel cells 31. The biofuel module 30 is configured by stacking a plurality of fuel cells 31 by being folded at the notches 32.

  In this biofuel cell module 30, each fuel cell 31 may be separable by a cut 32 or a fold. Thereby, the used fuel cell 31 can be easily removed, and the new fuel cell 31 can generate electric power. The biofuel cell module 30 of the present embodiment can also be used by connecting the fuel cells 31 in series or in parallel. The configuration and effects other than those described above in the present embodiment are the same as those in the first embodiment described above.

In addition, this indication can also take the following structures.
(1)
A biofuel cell module in which flat or sheet-like fuel cells having one or more power generation units each having an electrode having an oxidoreductase on the surface are stacked with the positions of the fuel supply units aligned.
(2)
The biofuel cell module according to (1), wherein fuel is supplied only to the uppermost or lowermost fuel cell.
(3)
The biofuel cell module according to (1) or (2), wherein each fuel cell is removable or replaceable.
(4)
A plurality of fuel cells are provided on one plate or sheet, and a cut or fold is formed between the fuel cells, and the plurality of fuel cells are stacked by folding the cut or fold (1 The biofuel cell module according to any one of (1) to (3).
(5)
The biofuel cell module according to (4), wherein each fuel cell can be separated by the cut or crease.
(6)
The power generation unit of each fuel cell is provided with a pair of electrodes constituting an anode or a cathode and a separator disposed between the electrodes to prevent a short circuit, and each electrode and / or separator can be exchanged. The biofuel cell module according to any one of (1) to (5).

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 31 Fuel cell 2 Fuel supply port and vent 3 Current collector 4 Fuel 5 Oxygen 10, 30 Bio fuel cell module 11 Anode 12 Separator 13 Cathode 14 Lid 15 Fuel diffusion layer 16 Gas-liquid separation membrane 17, 18 Sealing Material 19 Fuel Liquid Reservoir 20, 21 Terminal 22 Open / Close Tab 23 Insulation Tank 32 Notch

Claims (6)

  A biofuel cell module in which flat or sheet-like fuel cells having one or more power generation units each having an electrode having an oxidoreductase on the surface are stacked with the positions of the fuel supply units aligned.   The biofuel cell module according to claim 1, wherein fuel is supplied only to the uppermost or lowermost fuel cell.   The biofuel cell module according to claim 1, wherein each fuel cell is removable or replaceable.   A plurality of fuel cells are provided on one plate or sheet, a cut or fold is formed between the fuel cells, and a plurality of fuel cells are stacked by folding at the cut or fold. The biofuel cell module according to 1.   The biofuel cell module according to claim 4, wherein each fuel cell can be separated by the cut or fold.   The power generation unit of each fuel cell is provided with a pair of electrodes constituting an anode or a cathode and a separator disposed between the electrodes to prevent a short circuit, and each electrode and / or separator can be exchanged. The biofuel cell module according to claim 1.