JP2003022830A - Fuel cell power generation system, operation method for fuel cell power generation system, and battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell power generation system, capable of increasing output when the initial alcohol concentration of an alcohol-containing aqueous solution inside a container is increased. SOLUTION: This fuel cell power generation system is equipped with a power generation part; a container 10; an anode passage 9; an alcohol-containing aqueous solution recovering mechanism recovering the excess amount of it of the alcohol-containing aqueous solution supplied to the anode passage 9; and a flow rate control means controlling alcohol-containing aqueous solution supply amount Jm (mL/min) from the container 10, according to the alcohol concentration of the alcohol-containing aqueous solution inside the container, estimated from data recorded as a change with the passage of time by corresponding load current to the operation time, and (1) to (3) of formula 1 is satisfied.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fuel cell power generator, a method of operating the fuel cell power generator, and an assembled battery.

[0002]

2. Description of the Related Art As a power source for portable electronic devices that support an information-oriented society, and as a key element of electric vehicles and power storage systems for coping with air pollution and global warming, high performance secondary batteries and fuel cells have been developed. Expectations are very high. Particularly for application to electric vehicles, PEM (PEFC, solid electrolyte fuel cell) using hydrogen and oxygen as fuels has been regarded as a promising candidate. It is considered to be suitable for electric vehicles in two respects: high output can be obtained by using clean energy such as hydrogen and oxygen, and output can be restored by supplementing fuel. However, since the fuel cell has a drawback that the output decreases with a large change in load current, it is difficult to generate power during sudden acceleration. On the other hand, although an electric vehicle that runs on only a lithium-ion secondary battery has already been realized, an electric vehicle that uses only a lithium-ion secondary battery in view of safety issues and the fact that the output cannot be restored even if electrolyte is replenished. It is also considered difficult to apply to. Therefore, hybrid batteries (assembled batteries), which make the most of the features of both lithium-ion secondary batteries and fuel cells, have become important for application to electric vehicles. Furthermore, in order to solve the problem of reducing the fuel volume used for PEM, compressed hydrogen (250 atm),
A method of using liquid hydrogen, a hydrogen storage alloy, or the like as a fuel is also under study. Under such circumstances, a direct methanol fuel cell (DMFC) that generates electric power by directly extracting protons from methanol has a drawback that its output is smaller than that of a PEM, but it has been noted from this viewpoint. There is. Further, due to the feature that the fuel volume is small, the direct methanol fuel cell is considered to be applied to portable electronic devices, and the application to various fields is expected to be increased.

FIG. 1 shows a schematic structure of a standard direct methanol fuel cell. The electromotive section of the direct methanol fuel cell includes an anode electrode including the anode current collector 1 and the anode catalyst layer 2, a cathode electrode including the cathode current collector 3 and the cathode catalyst layer 4, the anode electrode and the cathode electrode. And an electrolyte membrane 5 disposed between the two. Anode channel plate 6
Are arranged on the anode current collector 1 side. As shown in FIG. 2, the anode flow channel plate 6 is formed with an anode flow channel 9 having a methanol supply port 7 and a methanol discharge port 8. A methanol aqueous solution container 10 containing a methanol aqueous solution is connected to a methanol supply port 7 via a pump 11. On the other hand, the cathode channel plate 12
Are arranged on the cathode current collector 3 side. The cathode channel plate 12 has an oxidant supply port 13 and an oxidant discharge port 14
Is formed in the cathode flow channel 15. An oxidant supply means 16 for supplying an oxidant such as air is connected to the oxidant supply port 13.

As the electrolyte membrane 5, for example, a Nafion membrane having high proton conductivity is used. On the other hand, the catalyst used in the anode catalyst layer 2 is, for example, P, which is less poisoned.
tRu is used, and the catalyst used in the cathode catalyst layer 4 is Pt, for example.

In such a direct methanol fuel cell, an aqueous methanol solution is supplied to the anode catalyst layer 2 to generate protons by a catalytic reaction, and the generated protons pass through the electrolyte membrane 5 and are supplied to the cathode catalyst layer 4. Electricity is generated on the principle that it reacts with oxygen on the catalyst.

In order to improve the output of the direct methanol fuel cell, it is necessary to maintain a high electromotive force up to a high load current. In order to obtain a high load current, it is necessary to increase the amount of methanol supplied to the anode catalyst layer per unit time. However, since the Nafion membrane also permeates an aqueous methanol solution, the aqueous methanol solution that has not been used in the reaction in the anode catalyst layer reaches the cathode catalyst layer and causes the same reaction as the anode catalyst layer in the cathode catalyst layer. Electromotive force is generated. This is a crossover overvoltage and causes a problem of reducing the electromotive force of the direct methanol fuel cell. This crossover overvoltage becomes more serious as the concentration of methanol increases.
When an aqueous methanol solution exceeding the above is supplied to the anode catalyst layer, the output is significantly reduced. Further, from the viewpoint of suppressing deterioration of an electrolyte membrane such as a Nafion membrane, it is preferable that the concentration of the aqueous methanol solution be 5 M or less.
Therefore, in order to operate the direct methanol fuel cell, it is preferable that the concentration of the aqueous methanol solution as the fuel be 5 M or less.

By the way, as a method of reducing the crossover overvoltage, a method of consuming all of the methanol supplied to the anode catalyst layer in the anode catalyst layer and preventing permeation to the cathode catalyst layer can be considered. For this purpose, there is a method of improving the catalyst activity in the anode catalyst layer or increasing the amount of catalyst supported, but it is not possible with the current catalyst. In addition, although an electrolyte membrane that does not allow the methanol aqueous solution that was not used in the anode catalyst layer to permeate is being developed, in reality, many electrolyte membranes have poor proton conductivity, which may reduce the output. Many. Therefore, in order to reduce the crossover overvoltage, it is preferable to reduce the concentration of the aqueous methanol solution used as fuel. However, when a low concentration fuel is used, it is necessary to make the fuel container large, so that the characteristics of the direct methanol fuel cell cannot be fully utilized.

As shown in FIG. 1 described above, the normal direct methanol fuel cell has a structure in which the pump 11 supplies the aqueous methanol solution to the anode flow channel plate 6. As described above with reference to FIG. 2, the aqueous methanol solution supplied from the pump 11 flows through the methanol supply port (inlet) 7 of the anode flow channel plate 6 to the groove portion (anode flow channel 9) of the flow channel plate 6. The convex portion of the flow channel plate 6 is in contact with the anode current collector 1 such as anode carbon paper, and the aqueous methanol solution flowing through the anode flow channel 9 is soaked in the anode current collector 1 so that the anode catalyst layer 2 Aqueous methanol solution is supplied to.

However, almost all of the aqueous methanol solution flowing through the anode flow channel plate 6 hardly penetrates into the anode current collector 1, and a part of it is discharged from the methanol outlet 8 of the flow channel plate 6. . Therefore, the utilization efficiency of the aqueous methanol solution in the container 10 is generally low. Attempts have been made to improve the structure of the flow channel plate in order to increase the efficiency, but the present situation is that the utilization efficiency has not been significantly increased. Further, it is conceivable to prepare a mechanism for returning the aqueous methanol solution discharged from the methanol outlet 8 of the anode flow channel plate 6 to the container 10, but in the anode catalyst layer 2 the methanol and water are 1: 1. Since it is consumed, when the aqueous methanol solution discharged from the anode flow channel plate 6 is returned to the container 10, the concentration of the aqueous methanol solution in the container 10 gradually decreases. As a result, there is a problem that a shortage of methanol occurs inside the battery and the electromotive force is sharply reduced.

As described above, it is desirable to use an aqueous methanol solution having a concentration of 5 M or less as a fuel. However, when a thin aqueous methanol solution is used as a fuel, not only the volume of the container needs to be increased, but also the reaction inside the battery is required. On the other hand, a shortage of methanol is likely to occur, and it is necessary to feed the aqueous methanol solution from the aqueous methanol solution container quickly. If such an operation is performed, the crossover overvoltage can be lowered, so the output as a battery increases, but
Since the pump output for supplying methanol also becomes large, there arises a problem that the output of the entire power generation device decreases conversely.

As described above, from the viewpoint of fuel supply, it is desirable to send a concentrated aqueous methanol solution at a low flow rate, but from the perspective of output, it is desirable to send a dilute aqueous methanol solution at a high flow rate. Occurs. Therefore, in order to reduce the fuel volume and obtain a high output, it is necessary to send an aqueous methanol solution having an optimum concentration at an optimum flow rate. The optimum concentration and flow rate of the aqueous methanol solution also depend on the structure of the battery electromotive section.
It is extremely difficult to systematically investigate experimentally, and it is not yet fully understood. Moreover, if optimization is performed by using a simulation, this problem can be solved promptly, but a theory that gives a sufficient explanation for the output of the direct methanol fuel cell has not been proposed yet.

[0012]

SUMMARY OF THE INVENTION The present invention provides a fuel cell power generator and an assembled battery capable of improving the output when the initial alcohol concentration of the alcohol-containing aqueous solution in the container is increased. To aim.

The present invention also provides a method of operating a fuel cell power generator capable of improving the output density when the initial alcohol concentration of the alcohol-containing aqueous solution in the container is within the range of 2 to 5 mol / L. The purpose is to do.

Further, according to the present invention, it is an object of the present invention to provide a fuel cell power generator and an assembled battery which are excellent in both fuel utilization efficiency and energy conversion efficiency.

[0015]

A first fuel cell power generator according to the present invention includes an anode electrode including an anode catalyst layer,
An electromotive unit including at least one electromotive unit including a cathode electrode and an electrolyte membrane disposed between the anode electrode and the cathode electrode, a container containing an alcohol-containing aqueous solution, and the anode electrode. An anode flow path for supplying the alcohol-containing aqueous solution to the, an alcohol-containing aqueous solution recovery mechanism for recovering an excess of the alcohol-containing aqueous solution supplied to the anode flow path into the container, and a load current at an operating time. A flow rate control means for controlling the alcohol-containing aqueous solution supply amount J _m (mL / min) from the container according to the alcohol concentration of the alcohol-containing aqueous solution in the container evaluated from the correspondingly recorded change over time. And the following numerical formula (1)-
It is characterized in that the condition (3) is satisfied.

[0016]

[Equation 4]

Where C ⁰ _m is the initial alcohol concentration (M) of the alcohol-containing aqueous solution in the container, L is the thickness (μm) of the anode catalyst layer, and S is the reaction of the anode catalyst layer. In an area (cm ² ), the N represents the number of the electromotive unit in the electromotive unit.

A second fuel cell power generator according to the present invention comprises:
An electromotive part comprising at least one electromotive part unit comprising an anode electrode having an anode catalyst layer having a thickness of 40 μm or more, a cathode electrode, and an electrolyte membrane arranged between the anode electrode and the cathode electrode. A fuel cell power generator comprising a container containing an alcohol-containing aqueous solution having an alcohol concentration of 2 M or more and 5 M or less, wherein the alcohol-containing aqueous solution supply amount J _m (mL / min) from the container.
Is within the range defined by the following equation (4).

[0019]

[Equation 5]

Where L is the thickness (μm) of the anode catalyst layer, S is the reaction area (cm ² ) of the anode catalyst layer, and N is the unit of the electromotive unit in the electromotive unit. Indicates the number of.

The assembled battery according to the present invention is the first battery according to the present invention.
Alternatively, it is characterized by including a second fuel cell power generator and a non-aqueous electrolyte secondary battery electrically connected to the fuel cell power generator.

In the method for operating a fuel cell power generator according to the present invention, an anode electrode including an anode catalyst layer having a thickness of 40 μm or more, a cathode electrode, and an electrolyte membrane disposed between the anode electrode and the cathode electrode. An electromotive part having at least one electromotive part unit, a container containing an alcohol-containing aqueous solution having an initial alcohol concentration in the range of 2M to 5M, and an alcohol-containing aqueous solution supplied to the anode electrode. From the anode flow path, an alcohol-containing aqueous solution recovery mechanism for recovering an excess amount of the alcohol-containing aqueous solution supplied to the anode flow path into the container, and a load current recorded as a change with time corresponding to an operating time. A fuel provided with an alcohol concentration evaluation mechanism for evaluating the alcohol concentration of the alcohol-containing aqueous solution in the container and calculating the evaluation concentration. A method of operating a cell power generator,
When the evaluation concentration is within the range of 2 M to 5 M, the alcohol-containing aqueous solution supply amount J _m (mL / mi from the container is
a first power generation step of obtaining power from the fuel cell power generator by maintaining n) at a constant value within the range of Expression (3) below, and when the evaluation concentration drops below 2M,
A second power generation step of obtaining power from the fuel cell power generator by increasing the supply amount J _m (mL / min) within the range of the expression (3). .

[0023]

[Equation 6]

Where L is a thickness (μm) of the anode catalyst layer, S is a reaction area (cm ² ) of the anode catalyst layer, and N is a unit of the electromotive unit in the electromotive unit. Indicates a number.

In the first and second fuel cell power generators and the method for operating the fuel cell power generators according to the present invention, examples of the alcohol-containing aqueous solution include a methanol-containing aqueous solution such as a methanol aqueous solution.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION In order to optimize the concentration of an aqueous methanol solution supplied to a direct methanol fuel cell and its flow velocity, the present inventor created a simulator and systematically examined the output characteristics as described above. Formulas (1) to (4) of Formulas 4 to 5 were derived.

Several equations have already been proposed for methanol conduction, proton conduction, and oxidant conduction in the electromotive section (for example, J. Power Source, 65, No. 1).
-2,159 (1997), Discussions of the Farady Society,
No. 21 (1956), J. Electrochem. Soc., 39, No. 9, 2477
(1992)), these formulas were also used in devising the present invention. That is, the catalytic reaction of the electrode is the Butler shown in the following Equation 7.
-Described by the Volmer equation.

[0028]

[Equation 7]

However, since α represents the number of electrons involved in the catalytic reaction, a value of 2 was used in the cathode catalyst layer and a value of 3 was used in the anode electrode. Also, the effective catalyst surface area a
And the exchange current i ₀ , as is commonly used,
10 ⁻⁵ (70 ° C.) in the cathode catalyst layer and 6.25 exp (8420 (1 / 333-1 /
T)) was used. However, although the activity of the catalyst has a strong dependence on the temperature, 70 ° C. which is generally considered as the operating temperature of the battery was assumed, and all calculations of the present invention were performed. Further, (φ _{H +} −φ _e− ) represents the potential difference between the electron and the proton.

[0030]

[Equation 8-1]

[0031]

[Equation 8-2]

Here, i represents the current density of protons carried by z, and C _m represents the concentration of methanol in z. The γC _m (z) is the number of methanol molecules hydrated by one proton, and is described in the literature (J. Electr.
ochem Soc., 147, No.2, 466 (2000)), γ = 2
5 cm ³ / mol was used. Further, the diffusion coefficient D _m (cm ² / sec) of methanol in the Nafion membrane is 4.
9 × 10 ^-6 exp {2436 (1 / 3333-1 / T)}
As the Nafion content ε in the electrode, a value of 0.5 was used assuming a catalyst layer supporting carbon black. Further, F is a Faraday constant, which is 96485C.
/ Mol. In addition, as the conduction of oxygen,
It is described by the Nernst-Planck equation with convection as shown in.

[0033]

[Equation 9]

However, k _φ = 7.18 × 10 ⁻¹⁶ cm ² , the viscosity of water μ = 3.56 × 10 ⁻⁴ kg / m / sec, and the concentration of fixed charges C _f = 1. 2 x 10 ^-3 mo
1 / cm ³ , diffusion coefficient of oxygen dissolved in the Nafion film (cm ² / sec) D _O2 = 3.1 × 10 ⁻³ exp (−
2768 / T) was used.

By calculating the above equations (7) to (9) in a self-consistent manner, the spatial dependence of the methanol concentration and the oxygen concentration in the electromotive section of the direct methanol fuel cell can be calculated. Further, the concentration of the aqueous methanol solution supplied from the aqueous methanol solution container to the electromotive section and the flow velocity of the solution are expressed as boundary conditions of the methanol equation of conduction. In the direct methanol fuel cell having the structure shown in FIG. 1 described above, the anode catalyst layer 2 has a thickness of 100 μm, and the electrolyte membrane 5 has a Nafion 117 product name manufactured by Dupont and a thickness of 200 μm. FIG. 3 shows the results of calculation of the spatial dependence of the methanol concentration when the cathode catalyst layer 4 has a thickness of 100 μm and a 2M aqueous methanol solution is fed at a flow rate of 1.3 mL / min. However,
The horizontal axis in FIG. 3 represents the moving distance (c
m), the vertical axis represents the aqueous methanol solution concentration (M) at the moving point.

As is clear from FIG. 3, it is found that an aqueous solution of methanol of about 0.25M permeates the cathode catalyst layer. The crossover overvoltage is generated by the methanol that permeates into the cathode catalyst layer, but since the equation that accurately describes the relationship between the methanol concentration and the crossover overvoltage has not been clarified, the output characteristics of the direct methanol fuel cell are not accurate. Could not be discussed. Therefore, in order to derive the relational expressions (1) to (3) in the present invention, the change in the current-voltage characteristic when the concentration of the aqueous methanol solution supplied to the anode catalyst layer was changed was measured, and based on the experimental results. , The equation giving the relationship between the crossover overvoltage and the concentration of methanol permeated into the cathode catalyst layer was derived. The measurement results are shown in FIG. However, in FIG. 4, the horizontal axis represents the current density (A / cm ² ) of the fuel cell, and the vertical axis represents the cell voltage (V).

As is clear from FIG. 4, the crossover overvoltage increases as the concentration of methanol supplied to the anode catalyst layer increases, and a remarkable voltage drop is observed. Next, a theoretical consideration of this phenomenon will be described. First, the methanol that has entered the cathode catalyst layer results in effectively reducing the Pt surface area that should react with the protons. Further, on Pt, methanol causes a four-electron reaction with oxygen to generate a proton. Therefore, a current is locally generated and a counter electromotive force is generated. The former effect is expressed as follows. The disappearance of protons on the cathode catalyst is given by the following equation 10.

[0038]

[Equation 10]

Therefore, the effective catalyst surface area a ′ for the protons changed by the entry of methanol into the cathode catalyst layer is expressed by the following equation 11.

[0040]

[Equation 11]

Further, (a / a ') is a cathode catalyst layer
Average methanol concentration in the electrode <C _m>^{1 / n}Proportional to
And is known as the Freundlich formula. Therefore,
Loss overvoltage ζ_xIs the darkness as shown in the following formula 12.
It is considered to have a degree dependency.

[0042]

[Equation 12]

Furthermore, since the voltage drop caused by the current of the protons generated by the crossover is considered to be proportional to the reaction rate of the direct reaction of methanol and oxygen, the concentration dependence proportional to <C _m > in the first order is shown. Hold. By adding this term to the equation of the above equation 12, the expression of the crossover overvoltage shown in the following equation 13 is obtained.

[0044]

[Equation 13]

However, since the current density of protons locally flowing due to crossover is given by α <C _m > / σ ^c _{H +} / L _c, when it becomes larger than the methanol flux flowing into the cathode catalyst layer, It is necessary to determine the coefficient α according to 14. However, since the methanol flux is generally smaller, the values of α, β, and γ are unknown.

[0046]

[Equation 14]

Therefore, these coefficients were determined from the above-mentioned current-voltage characteristics shown in FIG. 4, and the equation shown in the following equation 15 was obtained.

[0048]

[Equation 15]

Therefore, it becomes possible to systematically calculate the output characteristics of the direct methanol fuel cell based on the above equation.

Next, with respect to the fuel cell measured in FIG. 4, FIG. 5 shows the result of calculation of change in output density when the concentration and flow rate of the aqueous methanol solution to be supplied are changed. Here, the fuel cell measured in FIG. 4 is the same as in FIG.
The number of laminated layers N of the electromotive unit is 1
The thickness of the anode catalyst layer 2 is 100 μm. By the way, in FIG. 5, the vertical axis represents the output density.
The power density is defined by the maximum value of the product of the current density and the voltage, and the value obtained by multiplying this value by the cross-sectional area of the battery gives the power of the battery. The horizontal axis represents the concentration of the aqueous methanol solution supplied from the aqueous methanol solution container. Furthermore, each curve shows the power density change when the flow rate of the methanol aqueous solution sent per unit area of the anode catalyst layer is different.

As is apparent from FIG. 5, when the flow velocity is fixed, the power density has a maximum value with respect to the concentration of the aqueous methanol solution, and the maximum concentration of the aqueous methanol solution shifts to the low concentration side as the flow velocity increases. I know I'm going. That is, as the concentration of the aqueous methanol solution supplied from the aqueous methanol solution container increases, the amount of methanol that enters the anode catalyst layer increases, so that the limiting load current increases and the output also increases. However, when the amount of methanol supplied to the anode catalyst layer exceeds a certain amount, the amount of methanol that permeates to the cathode catalyst layer also increases, so the crossover overvoltage also increases, and conversely the output decreases. Therefore, the power density has the maximum value with respect to the concentration of the aqueous methanol solution supplied. It is also found that the maximum power density monotonically increases as the flow rate of the aqueous methanol solution is increased and saturates at 0.052 cm / min. This is explained by the fact that the output saturates because the maximum rate at which methanol can diffuse through the anode catalyst layer is determined by the anode catalyst layer thickness. That is, 0.0
Even if the aqueous methanol solution is supplied at a flow rate of 52 cm / min or more, the output does not increase, and conversely, the output of the battery device as a whole is reduced due to the increase of the pump output.

Further, FIG. 6 shows a diagram in which the concentration of the aqueous methanol solution supplied to the anode catalyst layer is within a desirable range of 5 M or less.

In FIG. 6, a battery device which feeds an aqueous methanol solution at a flow rate of 0.052 cm / min or less is a desirable battery device from the viewpoint of output. As described above, the upper limit flow velocity (0.052 cm / min) is determined by the methanol flow velocity at which the output is saturated, and the lower limit flow velocity (0.0015 cm).
(cm / min) is a flow rate for preventing fuel shortage when a 5 M aqueous methanol solution is sent. Further, since the optimum flow rate changes depending on the thickness of the anode catalyst layer, the calculation was similarly performed when the thickness of the anode catalyst layer was 40 μm. The result of this calculation is shown in FIG.

As is clear from FIG. 7, when the thickness of the anode catalyst layer is reduced to 40 μm, the methanol concentration at which the output is maximum shifts to the low concentration side, and the maximum output density can be obtained at the methanol concentration of 0.5M. I understand. In order to avoid a rapid methanol shortage, it is preferable to set the anode catalyst thickness at which the methanol concentration that maximizes the power density is 0.5 M or more. From these results, the thickness of the anode catalyst layer is preferably 40 μm or more. Further, as is clear from FIGS. 6 and 7, the flow rate (cm / min) of the methanol aqueous solution fed per unit area of the anode catalyst layer is within the range defined by the following equation 16 (N
= 1 and S = 1 cm ² ), the output density hardly changes in the range of 2 to 5 M in the methanol concentration of the methanol aqueous solution to be fed. Within the range defined by the following formula 16 (N = 1, S = 1 cm ² ), 0.0065 cm / min or more and 0.052 cm / mi surrounded by diagonal lines in FIG.
n or less, while 0.016 surrounded by diagonal lines in FIG.
The range is 25 cm / min or more and 0.13 cm / min or less.

[0055]

[Equation 16]

This is because the crossover phenomenon that occurs in the cathode catalyst layer is in a reaction rate limiting state. The flow velocity (cm / min) is 0.65 / L or less, that is, 0.0065 cm / min or less in FIG. 6, and 0.
It can be seen that when it is set to 01625 cm / min or less, in the range where the methanol concentration of the fed methanol aqueous solution is 2 M or less, a lack of methanol occurs in the anode catalyst layer, so that the output density decreases. However, the methanol concentration of the aqueous methanol solution to be sent is 2M or more and 5M
Below, it can be seen that there is a region where the power density increases even if the flow velocity is reduced. The range of the flow velocity where the output density increases is a region where the power consumption of the pump is reduced and the output density is increased at the same time, and it is considered that the energy conversion efficiency is significantly increased. This is the most optimal flow rate range for sending an aqueous methanol solution having a concentration. The range of the flow velocity in which the output density increases is within the range defined by the following formula 17 (N = 1, S =
1 cm ² ) is a region where a power density higher than that obtained when a flow velocity (5.2 / L) is flowed. Within the range defined by the following Equation 17 in FIG.
0.0015 cm / min or more, 0.0065 cm / m
It is less than or equal to in. On the other hand, the range defined by the following formula 17 in FIG. 7 means 6 × 10 ⁻⁴ cm / min or more, 0.
It is less than or equal to 01625 cm / min.

Further, this phenomenon is caused by the fact that the crossover reaction occurring in the cathode catalyst layer causes the supply rate control by lowering the methanol flow rate, and the overvoltage decreases.
It is explained that the power density increases. However, if the flow velocity of the fed methanol is 1.5 × 10 ⁻⁵ L or less, fuel shortage will occur even if the aqueous methanol solution having a methanol concentration of 5 M is fed.

[0058]

[Equation 17]

Further, in the above-described battery device having the structure shown in FIG. 1, the aqueous methanol solution discharged from the anode flow channel plate 6 was recovered through another route, but in the direct methanol fuel cell power generator according to the present invention, The methanol aqueous solution discharged from the anode channel is collected in a methanol aqueous solution container. FIG. 8 shows a schematic configuration of a main part of an example of the direct methanol fuel cell power generator according to the present invention. Figure 8
In the above description, the same members as those described with reference to FIG. Methanol aqueous solution recovery pipe 17 as a methanol aqueous solution recovery mechanism
Are connected between the methanol outlet 8 of the anode flow channel 9 and the methanol aqueous solution container 10.

According to the direct methanol fuel cell power generator having the structure as shown in FIG. 8, the methanol aqueous solution discharged from the anode channel 9 is supplied to the methanol aqueous solution container 1
Although it has an advantage that the volume of the methanol aqueous solution container 10 can be reduced by the amount of 0, the container 1
Since the concentration of the aqueous methanol solution in 0 gradually decreases, there is a possibility that a shortage of methanol will occur in the electromotive section, resulting in a sharp decrease in output. Therefore, as discussed above, by changing the flow rate of the aqueous methanol solution supplied according to the concentration of the aqueous methanol solution in the aqueous methanol solution container, it is possible to recover the output density even when the aqueous methanol solution concentration decreases. Becomes The range of the methanol flow rate J _m is given by the following equations (2) and (3).

[0061]

[Equation 18]

Where L in the equation (2) is the thickness (μm) of the anode catalyst layer of the direct methanol fuel cell.
In the equation (3), S is the reaction area (cm ² ) of the anode catalyst layer, N is the number of layers of the electromotive unit, and J _m is the aqueous methanol solution supply from the aqueous methanol solution container. Indicates the amount (mL / min). Here, when the number of pumps connected to the methanol aqueous solution container is one, the methanol aqueous solution supply amount J _m (mL
/ Min) is equal to the liquid delivery amount per unit time (minute) of the pump. Further, when the number of pumps connected to the methanol aqueous solution container is two or more, the methanol aqueous solution supply amount J _m (mL / min) is the sum of the liquid feeding amount per unit time (minute) of each pump. Equal to one.

Further, the concentration of methanol aqueous solution (initial concentration) C ⁰ _m (M) to be initially added to the aqueous methanol solution is set within the range defined by the following equation (1), and the aqueous methanol solution in the aqueous methanol solution container is set. If the flow velocity J _m is increased within the range defined by the above equation (3) as the concentration decreases, not only the output of the auxiliary device can be minimized, but also the volume of the methanol aqueous solution container is minimized. It becomes possible to do.

[0064]

[Formula 19]

The anode catalyst layer is preferably prepared by a method of supporting a catalyst on a conductive carbon black carrier (supporting method). By using the anode catalyst layer manufactured by the supporting method, the diffusion rate of the aqueous methanol solution can be improved, so that the output of the fuel cell can be further improved and the driving can be performed for a long time. Further, the manufacturing cost of the fuel cell power generator can be kept low.

The thickness of the anode catalyst layer L is 40 to 150.
It is preferably within the range of μm.

The porosity (Nafion content ε) of the anode catalyst layer is preferably within the range of 0.4 to 0.7. By setting the porosity within the above range, a high methanol aqueous solution diffusion rate can be obtained.

Further, for example, the thickness is 20 μm by the non-supporting method.
The following anode catalyst layer was produced, the concentration of the aqueous methanol solution was set to 1 M or less, and the flow rate of supplying the aqueous methanol solution was set to the upper limit value defined by the equation (3) of the above-mentioned equation 18, ie {(5.2 / L ) × S} (mL / min), as is apparent from FIGS. 6 and 7 described above,
Although it is possible to increase the output density, the output of the auxiliary device increases, so the output density obtained from a fixed amount of methanol decreases. Moreover, since the concentration of the aqueous methanol solution is low, the volume of the aqueous methanol solution container must be increased. Therefore, as in the present invention, a high-concentration aqueous methanol solution is stored in the aqueous methanol solution container from the beginning, the thickness of the anode catalyst layer is increased, and the supply rate of the aqueous methanol solution is set in consideration of the aqueous methanol solution concentration in the container. While slowly flowing, it is possible to increase the output density while achieving downsizing of the methanol aqueous solution container and reduction of the output of the auxiliary device.

In the present invention, the thickness is 40 μm.
It is composed of an electromotive unit including an anode electrode including the following anode catalyst layer, a cathode electrode, and an electrolyte membrane arranged between the anode electrode and the cathode electrode, or a plurality of the electromotive unit units are laminated. And a container storing an alcohol-containing aqueous solution having an alcohol concentration of 2 M or more and 5 M or less, wherein the alcohol-containing aqueous solution supply amount J _m (mL /
(min) is within the range defined by the equation (4) of the following mathematical expression 20, and thus the fuel cell power generator is provided.

[0070]

[Equation 20]

Where L is the thickness (μm) of the anode catalyst layer, S is the reaction area (cm ² ) of the anode catalyst layer, and N is the unit of the electromotive unit in the electromotive unit. Shows the number of laminated layers. Here, when the number of pumps connected to the container is one, the supply amount J _m (mL / min)
Is equal to the amount of liquid delivered per unit time (minute) of the pump. When the number of pumps connected to the container is two or more, the supply amount J _m (mL / min) is equal to the sum of the liquid supply amount per unit time (minute) of each pump. The alcohol-containing aqueous solution may be, for example, a methanol-containing aqueous solution such as a methanol aqueous solution.

According to such a fuel cell power generator, the ratio of the alcohol-containing aqueous solution actually permeated into the anode catalyst layer is increased in the fixed amount of the alcohol-containing aqueous solution supplied from the anode flow path to the anode catalyst layer. Therefore, high fuel utilization efficiency can be obtained without collecting excess alcohol-containing aqueous solution in the container.
Further, since the supply amount J _{m of the} aqueous solution is a low flow rate, and at the same time, the output density can attain the maximum value obtained at that flow rate, the energy conversion efficiency of the fuel cell can be improved. Therefore, it is possible to realize a fuel cell power generator having excellent fuel utilization efficiency and energy conversion efficiency.

[0073]

Embodiments of the present invention will now be described in detail with reference to the drawings.

The first direct methanol fuel cell power generator according to the present invention will be described with reference to FIGS. 8 and 9 to 12 described above.

FIG. 9 is a diagram schematically showing the construction of an embodiment of the first direct methanol fuel cell power generator according to the present invention, and FIG. 10 is a direct methanol fuel cell power generator of FIG. 11 is a perspective view showing the anode electrode of FIG. 11, FIG. 11 is a schematic view showing a state in which electromotive portions of a direct methanol fuel cell are stacked in series, and FIG. 12 is a first direct methanol fuel cell according to the present invention. It is a flowchart which shows an example of the procedure for implementing a power generator.

The fuel cell electromotive section is composed of one fuel cell electromotive section unit 21. Fuel cell electromotive unit 21
For example, as shown in FIG. 8 described above, the anode flow channel plate 6, the anode current collector 1, the anode catalyst layer 2, the electrolyte membrane 5, the cathode catalyst layer 4, the cathode current collector 3 and the cathode flow channel plate 13 are arranged. Prepare A methanol aqueous solution container 10 containing a methanol aqueous solution, which is an example of an alcohol aqueous solution, is connected to a methanol supply port 7 of an anode flow channel plate 6 via a liquid feed pump 11. Further, the methanol discharge port 8 of the anode flow channel plate 6 is connected to the methanol aqueous solution container 10. The oxidant supply means 16 for supplying an oxidant such as air is connected to the oxidant supply port 13 of the cathode flow channel plate 12 via a blower fan 22. Further, a heater (not shown) for heating the fuel cell electromotive section is attached to both the anode flow channel plate 6 and the cathode flow channel plate 13. The power source 23 of the auxiliary device is directly connected to the direct methanol fuel cell in order to drive the auxiliary device including the liquid feed pump 11, the blower fan 22 and the heater with the output of the direct methanol fuel cell.

According to the concentration of the aqueous methanol solution in the aqueous methanol solution container 10 which is evaluated by recording the load current as a change with time corresponding to the operating time, the aqueous methanol solution supply amount J from the aqueous methanol solution container 10 is determined.
_The flow rate control means for controlling _m (mL / min) includes a methanol flow rate control device 24 and a current aging record evaluation device 2.
6 and 6. The methanol flow rate control device 24 is connected to the liquid feed pump 11. The external circuit 25 is connected to the fuel cell electromotive section. Current aging change recording evaluation device 2
6 is connected to the methanol flow rate control device 24 and the external circuit 25.

According to such a flow rate controlling means, the time-dependent change of the current output from the direct methanol fuel cell 21 to the external circuit 25 is recorded by the current time-dependent change recording / evaluating device 26, and the methanol aqueous solution evaluated from the data is recorded. Container 1
The amount of liquid fed by the liquid feed pump 11 can be controlled by the methanol flow controller 24 according to the concentration of the methanol aqueous solution in zero. That is, here, the amount of liquid to be fed by the liquid feed pump 11 every time is regarded as the amount of aqueous methanol solution supply J _m (mL / min) from the aqueous methanol solution container 10. When a plurality of liquid feed pumps are provided, the methanol aqueous solution supply amount J _m (mL / min) is equal to the sum of the liquid feed amount per unit time (minute) of each pump.

The power generator shown in FIG. 9 satisfies the conditions (1) to (3) of the following expression 21.

[0080]

[Equation 21]

However, the C ⁰ _{m in the} equation (1) is the concentration (initial concentration) (M) of the aqueous methanol solution initially contained in the aqueous methanol solution container 10. The L in the equation (2) is the thickness of the anode catalyst layer 2 (μ
m). On the other hand, S in the equation (3) is a reaction area (cm ² ) of the anode catalyst layer 2, and is a hatched region in the case of FIG. 10. Further, N represents the number of stacked layers in the electromotive unit (power generation unit) unit, and is 1 in the case of the power generation device shown in FIG. When the stacking number of the electromotive unit 21 is 1 as shown in FIG. 9, the flow rate of the aqueous methanol solution flowing through the anode flow channel 9 is the aqueous methanol solution supply amount J _m (mL / min) from the aqueous methanol solution container 10. Is almost equal to.

The power generation device shown in FIG. 9 can include a plurality of fuel cell electromotive unit units. Figure 11
An example of stacking a plurality of fuel cell electromotive unit units 21 in series is shown in FIG. In this case, the methanol aqueous solution is supplied to each fuel cell electromotive unit 21 and is discharged from each fuel cell electromotive unit 21 as shown in the methanol flow path of arrow 27 in FIG. Are collected in one path and collected in the methanol aqueous solution container 10 (parallel liquid transfer method). In this case, the flow rate of the aqueous methanol solution in the anode flow channel 9 of each electromotive unit 21 is approximately equal to the amount of the aqueous methanol solution supply J _m (mL / min) divided by the number of laminated electromotive units.

On the other hand, another fuel cell electromotive unit is laminated on the fuel cell electromotive unit unit 21 of FIG.
By connecting the methanol discharge port 8 of the first anode flow channel plate 6 and the methanol supply port 7 of the anode flow channel plate 6 of another fuel cell electromotive unit, the stacked electromotive unit is
It is also possible to feed methanol through a single methanol flow path that does not branch (series feed method). In this case, the flow rate of the aqueous methanol solution flowing through the anode flow channel 9 is substantially equal to the supply amount J _m (mL / min) of the aqueous methanol solution.

A method is also possible in which a plurality of liquid feed pumps are provided, and each pump feeds liquid to several electromotive sections in series and bundles the paths in parallel. in this case,
The methanol aqueous solution supply amount J _m (mL / min) is equal to the sum of the liquid supply amounts per unit time (minute) of each pump.

Since a single direct methanol fuel cell has an electromotive force of 0.6 V or less, for example, a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery having a maximum electromotive force of 4.2 V. In order to charge the battery, it is necessary to stack 10 or more direct methanol fuel cells in series.

The first direct methanol fuel cell power generator according to the present invention can be used as a portable charger and can be used for charging various electronic devices, and thus can be used for industrial purposes. Of high value.

Next, a means for evaluating the concentration of the aqueous methanol solution in the aqueous methanol solution container from the change with time of the load current obtained from the direct methanol fuel cell will be described. Briefly, assuming that the current flowing into the external circuit at time t is I (t), the methanol aqueous solution concentration C _m (t) in the methanol aqueous solution container is given by the following formula 22.

[0088]

[Equation 22]

The equation (22) is based on the fact that the reaction in the anode catalyst layer consumes one molecule of methanol molecule and one molecule of water molecule. However, C ⁰ _m is the concentration of the methanol aqueous solution initially contained in the methanol aqueous solution container (initial concentration)
(M), V _m is the molar volume of methanol, V _w is the molar volume of water, and V is the volume of the methanol aqueous solution container.

To obtain a more accurate methanol concentration, it is possible to measure the quantity of electricity flowing to the external circuit and the methanol concentration of the methanol aqueous solution container and experimentally derive the relationship, and store it in the device. By doing so, it becomes possible to accurately change the flow rate of the aqueous methanol solution to be sent by recording and evaluating the change over time of the current flowing out from the inside of the device. Furthermore, if the relationship between the amount of electricity flowing out to the external circuit and the methanol concentration in the methanol aqueous solution container is stored inside the device, it is possible to know at what point in time the methanol aqueous solution in the methanol aqueous solution container needs to be replaced, and it is commercially available. As with the next battery, it is also possible to give a sign that the battery is dead, which is industrially advantageous.

Various methods are conceivable for detecting the concentration of the aqueous methanol solution in the aqueous methanol solution container. For example, a method of connecting a device for detecting the concentration of aqueous methanol solution such as a methanol sensor to the circuit in the battery device as an auxiliary device can be considered. However, considering that the methanol sensor has not yet been developed and the cost will increase. Then, it is unlikely to be appropriate. It is also possible to measure the concentration inside the container by utilizing the fact that the electric resistance changes depending on the concentration of the methanol aqueous solution, but it is appropriate considering the point that the circuit becomes complicated and the power consumption is large. I don't think so. Furthermore, it is possible to float the float inside the container, detect the position of the liquid surface inside the container, and evaluate the methanol concentration inside the methanol aqueous solution, but as the container volume decreases, it becomes difficult to measure. It is thought to go. Therefore, in the direct methanol fuel cell power generator according to the present invention, a means for evaluating the methanol aqueous solution concentration of the methanol aqueous solution container from the total amount of electricity obtained from the cell is adopted.

An example of the method for implementing the first direct methanol fuel cell power generator according to the present invention will be described with reference to FIG.

At the start, the parameters in the flow chart
The meter Q is set to 0. Loop during time Δt
Run every second. In the current aging record evaluation device 26,
Flow from the direct methanol fuel cell 21 to the external circuit 25
After measuring the output current I (t) as a change with time, Q = Q +
The process represented by I (t) Δt, that is, the electric quantity Q is calculated.
Current is integrated over time to obtain
Concentrated methanol in the methanol solution container 10 using Q
Degree C is evaluated. Methanol concentration using the calculation result Q
The evaluation of the degree C is performed using, for example, the formula of the above-mentioned formula 22.
I can. As shown in FIGS. 6 and 7 described above,
The concentration of the aqueous methanol solution in the tanol aqueous solution container 10
Flow rate below 2M to supply aqueous methanol solution
A higher value makes it easier to obtain a higher power density. F
C in the row chart_AIs set to 2M methanol concentration
The methanol in the methanol aqueous solution container 10
Concentration C is C_AIs equal to or exceeds
To continue power generation without changing the output of the liquid pump 11,
The first power generation step is performed. Conversely, C_A More methano
When the methanol concentration C in the aqueous solution container 10 has dropped
If the output of the liquid feed pump 11 is the flow velocity J_mAs mentioned above
Continuously so as to satisfy the range defined by equation (3).
Power generation while continuing to increase, that is,
The second power generation step is performed. However, methanol
The methanol concentration C in the aqueous solution container 10 is C _BGoing down
The battery runs out and the aqueous methanol solution
A command is given to replace the container 10. By the way
As shown in FIGS. 6 and 7 described above, a methanol aqueous solution container
When the methanol concentration C in 10 is less than 0.5 M,
Speed J _mIt is difficult to obtain high power density even if
is there. Therefore, methanol concentration C_BIs set to 0.5M
Preferably.

When power generation by the direct methanol fuel cell power generator is interrupted, it is preferable to store the value of the parameter Q at the time of interruption. When the power generation is restarted, by setting the parameter Q at the time of interruption to the initial value, the methanol concentration C in the methanol aqueous solution container 10 can be calculated more accurately.

Next, a second direct methanol fuel cell power generator according to the present invention will be described with reference to FIGS. 13 to 15.

FIG. 13 is a diagram schematically showing the structure of one embodiment of the second direct methanol fuel cell power generator according to the present invention, and FIG. 14 is the direct methanol fuel cell power generator of FIG. 15 is a schematic diagram showing an electromotive unit in FIG.
FIG. 6 is a flow chart showing an example of a procedure for implementing the second direct methanol fuel cell power generation device according to the present invention. 13 to 14, the same members as those in FIGS. 8 to 9 described above are designated by the same reference numerals and the description thereof will be omitted.

In the second direct methanol fuel cell power generator, the methanol aqueous solution container 10 is determined according to the concentration of the methanol aqueous solution in the methanol aqueous solution container (first methanol aqueous solution container) 10 evaluated from the change with time of the load current.
And a methanol replenishing means for replenishing the aqueous methanol solution. Such a methanol replenishing means is the second methanol aqueous solution container 27 (methanol replenishing container).
And a second liquid feed pump 28. The methanol flow control device 24 and the current aging record evaluation device 26 are shared by the flow control means and the methanol replenishing means. The second aqueous methanol solution container 27 is connected to the first aqueous methanol solution container 10 via a second liquid feed pump 28. In addition, the second methanol aqueous solution container 27
It is desirable that the concentration of the aqueous methanol solution be higher than the initial concentration C ⁰ _m . The liquid feed pump 28 is connected to the methanol flow rate control device 24.

According to such a methanol replenishing means,
The time-dependent change of the load current output from the direct methanol fuel cell 21 to the external circuit 25 is recorded in the current time-dependent change evaluation device 26, and from the recorded change of the load current with time, the methanol of the first methanol aqueous solution container 10 is recorded. Evaluate the concentration. In the methanol flow rate control device 24, a command is sent to the second liquid feed pump according to the evaluated methanol concentration, and liquid is fed from the second methanol aqueous solution container 27 to the first methanol aqueous solution container 10.

As shown in FIGS. 6 and 7 described above, the first
When the concentration of the aqueous methanol solution in the aqueous methanol solution container 10 becomes lower than 0.5 M, the output sharply decreases. Therefore, when the concentration of the aqueous methanol solution in the first aqueous methanol solution container 10 becomes less than 0.5 M, it is necessary to replace the aqueous methanol solution container with the aqueous methanol solution remaining. Therefore, the second methanol aqueous solution container 2
By sending a concentrated aqueous methanol solution from 7 to the first aqueous methanol solution container 10 to make the concentration of methanol in the first aqueous methanol solution container 10 0.5 M or more,
It becomes possible to continue the second power generation process by reusing the aqueous methanol solution in the first aqueous methanol solution container 10, and the aqueous methanol solution in the container 10 can be used up. Further, since the second methanol aqueous solution container 27 is exclusively used for replenishment, it is possible to replace the second methanol aqueous solution container 27 when all the methanol aqueous solution in the second methanol aqueous solution container 27 is used up. Become.
Further, by replenishing the first methanol aqueous solution container 10 with the methanol aqueous solution from the second methanol aqueous solution container 27, the concentration of methanol in the first methanol aqueous solution container is returned to the initial state, the output is recovered, and the first methanol aqueous solution container 10 is restored again. It is also possible to perform the first power generation step.

Therefore, according to the second direct type methanol fuel cell power generator, not only is it easy to determine when to replace the methanol aqueous solution container, but it is industrially convenient for collecting the used methanol aqueous solution container. Becomes Further, as can be understood from the above discussion, in order to store the concentrated methanol aqueous solution in the second methanol aqueous solution container,
The volume can be made smaller than the volume of the first methanol aqueous solution container. Therefore, the volume of the fuel container of the direct methanol fuel cell can be minimized. Moreover, since the liquid is not fed from the second methanol aqueous solution container 27 until the methanol concentration in the first methanol aqueous solution container 10 becomes less than 0.5 M, the output of the entire device is output by the output of the liquid feeding pump 28. It is possible to avoid a significant decrease, and it becomes possible to drive for a long time.

An example of the method of implementing the second direct methanol battery power generator will be described with reference to FIG.

At the start point, the parameters Q and N are set to 0. The process from the measurement of I (t) to the process of comparing the methanol concentrations C and C _B is performed in the same manner as described with reference to FIG. When the first methanol concentration C in methanol aqueous solution container 10 to be evaluated from the electric quantity Q is below C _B, to actuate the liquid feed pump 28 sends a signal to the liquid feed pump 28 from the methanol flow rate control device 24 ,
The aqueous methanol solution is sent from the second aqueous methanol solution container 27 to the first aqueous methanol solution container 10. It is preferable that the amount of the methanol aqueous solution container for feeding the liquid is always the same amount, and the amount of the liquid required for restoring the methanol concentration in the first methanol aqueous solution container 10 to the initial state is fed. A high output can be maintained by this liquid feeding.

It is necessary to reset the parameter Q to 0 since the initial state is returned after the liquid feeding. By repeating this process, the number of times N _{c of} liquid feeding is the second methanol aqueous solution container 27.
At the time when the number of times of liquid feeding N used up of the aqueous methanol solution is exceeded, the battery is dead, and an instruction is given to replace the second aqueous methanol solution container 27.

When power generation by the direct methanol fuel cell power generator is interrupted, it is preferable to store the values of the parameters Q and N at the time of interruption. When the power generation is restarted, the parameters Q and N at the time of interruption are set to initial values, so that the methanol concentration C in the methanol aqueous solution container 10 can be calculated more accurately.

An example of the assembled battery according to the present invention will be described with reference to FIG.

FIG. 16 is a schematic diagram showing the schematic structure of an example of the assembled battery according to the present invention. In addition, in FIG.
The same members as those in FIGS. 9 and 13 described above are designated by the same reference numerals, and the description thereof will be omitted.

This battery pack is a battery pack of a direct methanol fuel cell and a non-aqueous electrolyte secondary battery (for example, a lithium ion secondary battery). The portion of the direct methanol fuel cell has the same configuration as that of the second direct methanol fuel cell power generator described above, except that the number of stacked electromotive units is 10 or more. The direct methanol fuel cell and the lithium ion secondary battery 29 are connected in parallel. Further, a converter 30 is interposed between the direct methanol fuel cell and the lithium ion secondary battery 29, and the voltage of the direct methanol fuel cell is always set to 4.2V. In addition, an external device (external circuit) 31 that uses the secondary battery 29 as a driving power source is connected to the lithium ion secondary battery 29. When the lithium-ion secondary battery 29 is discharged and the external device 31 is driven, the switch 32 between the converter 30 and the lithium-ion secondary battery 29 is in an open state. However, the switch 32 is always on so that the lithium ion secondary battery can be charged when the external device 31 is not driven. Since it takes a long time to charge the lithium-ion secondary battery, it is expected that it will take about half a day if it is applied to an electric vehicle. Further, there is a drawback that the lithium ion secondary battery cannot be charged in a place without an external power source. Therefore, by connecting the direct-type methanol fuel cell to the lithium-ion secondary battery, the lithium-ion secondary battery can always be charged when not being discharged, so that not only the charging time can be shortened, It is also advantageous in that it requires no external power source because it can be charged simply by supplementing the aqueous methanol solution. Furthermore, if the lithium-ion secondary battery is over-discharged, it has the drawback that the original capacity cannot be obtained even if it is recharged. It becomes possible, and it is possible to avoid the capacity decrease due to over-discharge. As described above, the battery pack with the lithium ion secondary battery is most effective, but the battery pack with the capacitor or the nickel-hydrogen secondary battery is also possible in principle.

(Example 1) <Preparation of electromotive section of direct methanol fuel cell> Known process (R. Ramakumar et al. J. Power Sources 69 (1
997) 75), the catalyst for the anode (Pt: Ru = 1:
1) Supported carbon black and cathode catalyst (Pt) supported carbon black were prepared. The amount of catalyst supported was 30 for the anode and 15 for the cathode in a weight ratio with respect to 100 carbon.

[0109] A perfluorocarbon sulfonic acid solution (Nafion solution SE-20092 manufactured by Dupont) and ion-exchanged water were added to the catalyst-supporting carbon black for anode prepared in the above process, and the catalyst-supporting carbon black was dispersed to prepare a paste. . The anode electrode was obtained by applying 550 μm of the paste on a water repellent treated carbon paper TGPH-120 (manufactured by E-TEK) as an anode current collector and drying it to form an anode catalyst layer.

A perfluorocarbon sulfonic acid solution (Nafion solution SE-20092 manufactured by Dupont) and ion-exchanged water were added to the catalyst-supporting carbon black for cathode prepared in the above process, and the catalyst-supporting carbon black was dispersed to prepare a paste. 225 μm of the paste was applied on a water repellent treated carbon paper TGPH-090 (manufactured by E-TEK) as a cathode current collector and dried to form a cathode catalyst layer, whereby a cathode electrode was obtained.

Between the anode catalyst layer of the anode electrode and the cathode catalyst layer of the cathode electrode, a commercially available perfluorocarbon sulfonic acid membrane (Dupont Nafion 11
7) was placed and subjected to hot pressing (125 ° C., 5 minutes, 50 kg / cm ² ) to join the anode electrode, the electrolyte membrane and the cathode electrode to obtain an electromotive portion. The cross-sectional area S of the anode catalyst layer in the electromotive section is 10 cm.
^{Was 2} . When the electromotive section was cut and the cross-sectional area was observed with an electron microscope, the thickness L of the anode catalyst layer was 105.
In μm, the thickness of the cathode catalyst layer was 50 μm. Moreover, it was possible to confirm that the anode electrode, the electrolyte membrane, and the cathode electrode were in good contact with each other by observing with this electron microscope.

<Fabrication of Direct Methanol Fuel Cell> The fabricated electromotive section was mounted on a carbon separator and tightened with a screw to seal it. A silicon rubber heater was attached to the separator, and a commercially available temperature controller was used to control the temperature inside the holder to always be 70 ° C.

By the way, in the separator located on the anode electrode side, the anode flow channel 9 having the shape as shown in FIG. 2 is formed. A supply tube was connected to the methanol supply port 7 of the anode flow channel 9 and a discharge tube was connected to the methanol discharge port 8 of the anode flow channel 9.
A container 10 (volume: 10 mL) contains an aqueous methanol solution as an example of an aqueous alcohol solution, and a commercially available liquid feed pump 11
Was used to supply the liquid to the anode channel 9 through the supply tube and the supply port 7. The aqueous methanol solution, which had not penetrated into the anode carbon paper as the anode current collector, was discharged from the discharge tube through the methanol discharge port 8.

On the other hand, also in the separator located on the cathode electrode side, the cathode flow channel 15 having the same shape as the anode flow channel is formed.
Are formed. Oxidant supply port 1 of cathode channel 15
3 is connected to the supply tube, and the cathode channel 15
A discharge tube was connected to the oxidant discharge port 14 of. Air was supplied by using a commercially available air pump, and was supplied to the cathode channel 15 through the supply tube and the supply port 13. The air flow rate was adjusted using a commercially available mass flow controller.

The liquid is fed from 0.01 μL / min to 6 mL / min.
It can be adjusted in the range of up to min, and air supply is 20 mL /
It was confirmed that the adjustment was possible within the range from min to 5 L / min. A commercially available electronic load machine was used for the load.
Further, a commercially available digital multimeter was used as the voltage detecting means. Thus, the direct methanol fuel cell power generator having the structure shown in FIGS. 8 and 9 was obtained.

In the obtained fuel cell power generator, the flow rate of the aqueous methanol solution J _m (m
L / min) setting allowable range is 0.062 ≦ J _m ≦
It becomes 0.50.

<Measurement of Current-Voltage Characteristics> As the aqueous methanol solution in the aqueous methanol solution container 10, those having a methanol concentration C ⁰ _m of 5M, 4M, 3M, 2M, 1M and 0.5M were prepared. Flow rate J _m
Is 0.05 mL / min, 0.1 mL / min, 0.2
When the liquid was sent at mL / min and 0.4 mL / min, the voltage value for a constant load current of 1.5 A was measured. The experimental results are shown in FIG. The horizontal axis of FIG. 17 indicates the container 1
Initial concentration C ⁰ _m (M) of the aqueous methanol solution in ⁰ ,
The vertical axis represents the battery voltage (V).

When the solution was sent at a flow rate J _m of 0.05 mL / min, the concentration C ⁰ _{m of the} aqueous methanol solution was about 3.
The voltage value became 0 at 2 M or less. However, 0.2 mL /
If the flow rate J _m is increased to min, the methanol concentration C ⁰
_The voltage was obtained even when a methanol aqueous solution container with _m of 2.6 M or less was obtained, and the result was that the voltage increased at all concentrations. Furthermore, although the flow rate J _m was increased to 0.4 mL / min, it was found that there was almost no change and that the flow rate J _m at 0.2 mL / min was almost saturated. Since the output of the auxiliary device can be made smaller as the flow rate J _m is lower, the optimum flow rate J _{m in} this case is 0.2 mL / min.

Therefore, the methanol concentration C ⁰ _m of the aqueous methanol solution initially put in the aqueous methanol solution container 10 is set to 2
5M, the thickness L of the cathode catalyst layer 2 is 40 μm or more, and the supply flow rate J _{m of the} aqueous methanol solution is a value within the range regulated by the formula (3) (0.2 m in this case).
By setting a low flow rate of L / min),
A sufficient voltage of 0.25 to 0.35V can be obtained. Further, since the initial methanol concentration C ⁰ _m is as high as 2 to 5 M, the volume of the methanol aqueous solution container 10 can be reduced. Furthermore, since the supply flow rate J _m that can obtain a high voltage can be set within the range regulated by the above-described formula (3) (for example, 0.2 mL / min), the output of the auxiliary device can be suppressed. Therefore, the power density obtained from a fixed amount of methanol can be increased.

(Example 2) In the direct methanol fuel cell power generator of Example 1, an aqueous methanol solution having an initial concentration C ⁰ _m of 2 M was supplied to the anode catalyst layer at a flow rate J _m of 0.2 mL / min. Current-voltage characteristics (Example 1) when air was supplied to the cathode catalyst layer at a flow rate of 500 mL / min, and an aqueous methanol solution having an initial concentration C ⁰ _m of 1 M was set at a flow rate J _m of 0.2 mL / min to make the anode catalyst layer. And the air was supplied to the cathode catalyst layer at a flow rate of 500 mL / min, the current-voltage characteristics (Example 2) were measured, and the measurement results are shown in FIG.

From FIG. 18, in the fuel cell power generator of Example 1 which satisfies the relational expressions (1) to (3) described above, the output density of 53 mW / cm ² is obtained, while the initial concentration C ⁰ _m is It can be seen that the output density of the fuel cell power generator of Example 2 which is lower than the expression (1) is 45 mW / cm ² which is lower than that of Example 1.

Furthermore, in the fuel cell power generators of Example 1 and Example 2, the solution flow rate J _{m of the} aqueous methanol solution was 0.8 m.
It changed into L / min and the result is shown in FIG.

As is clear from FIG. 19, the initial concentration C ⁰ _m
In the fuel cell power generator of Example 1 in which the output power is 2 M, the output density is 6
In the fuel cell power generation device of Example 2 in which 3 mW / cm ² was obtained and the initial concentration C ⁰ _m was 1 M, the output density was 81 mW /
cm ² was obtained. 2M by quadrupling the flow rate
No sharp increase in output was observed when using the 1 M aqueous methanol solution, whereas when using the 1 M aqueous methanol solution, the output density increased to nearly double, and when the 2 M aqueous methanol solution was used. The result is that the power density is larger than that of the above. However, the liquid flow rate J _m is 0.
When it becomes larger than the range regulated by the above-mentioned formula (3) at 8 mL / min, the output of the auxiliary device increases and the output density obtained from a fixed amount of methanol becomes low.

(Example 3) In the direct methanol fuel cell power generator of Example 1, an aqueous methanol solution having a concentration C ⁰ _m of 2 M was supplied to the anode catalyst layer at a flow rate J _m of 0.2 mL / min to obtain air. Was supplied to the cathode catalyst layer at a flow rate of 500 mL / min, and the change in voltage was measured while flowing a load current of 1.5 A. The measurement result is shown in FIG.
However, the horizontal axis of FIG. 20 is the elapsed time (h). The vertical axis on the right side is the concentration C _m (t) (M) of the aqueous methanol solution in the container 10 estimated from the above-mentioned formula 22, and the vertical axis on the left side is the battery voltage (V). The voltage was constant at about 0.37 V until a current was passed for 50 minutes, but immediately after that, the voltage drastically decreased. The concentration C _m (t) of the methanol aqueous solution container estimated from the above-mentioned equation 22 is 1.
It was 2M. From the current-voltage characteristics when the 1 M aqueous methanol solution shown in FIG. 18 was used (Example 2), it was assumed that the methanol fuel shortage had occurred. Therefore,
When the flow rate of methanol feed J _m is doubled to 0.4 mL / min, it becomes possible to take the load current of 1.5 A again, the voltage is restored to about 0.45 V, and the load current is further passed for 30 minutes. I was able to continue.

After the measurement, the methanol concentration of the aqueous methanol solution in the aqueous methanol container was measured by gas chromatography and found to be 0.6M. The remaining amount of the aqueous methanol solution in the container was about 9 mL.

(Example 4) At the time when the experiment of Example 3 was completed, the second aqueous methanol solution container 27 was connected to the aqueous methanol solution container 10 of the fuel cell power generator via the liquid feed pump 28, and the above-mentioned diagram was used. 13 and a second direct methanol fuel cell power generator having the configuration shown in FIG.

5 mL of a 15 M aqueous methanol solution was placed in a second aqueous methanol solution container 27 having a volume of 10 mL,
From the second methanol aqueous solution container 27, 1 mL of the methanol aqueous solution was poured into the first methanol aqueous solution container 10.
As a result, the first methanol aqueous solution container 10 contains 10 mL of an approximately 2M aqueous methanol solution. The methanol aqueous solution in the first methanol aqueous solution container 10 was supplied to the anode catalyst layer at a flow rate J _m of 0.2 mL / min, and air was supplied to the cathode catalyst layer at a flow rate of 500 mL / min to load 1.5 A. When the change in voltage was measured while passing a current, a constant voltage of approximately 0.37 V was obtained. Therefore, load current of 1.5A to 1
After 20 minutes of time, the first methanol solution container 10 was replenished with 1 mL of methanol solution from the second methanol solution container 27, and a load current of 1.5 A was applied again. By repeating this operation 5 times, continuous driving could be performed for 6 hours and 40 minutes. After that, when the methanol concentration in the first methanol aqueous solution container 10 was measured by gas chromatography, it was about 0.7 M,
It was also confirmed that 9 mL remained. Meanwhile, the second
Almost no aqueous methanol solution was left in the aqueous methanol solution container 27.

Therefore, the first methanol aqueous solution container 10
It was possible to obtain a high power density for a long time without exchanging the aqueous methanol solution therein. Moreover, since the methanol concentration of the second methanol aqueous solution container was as high as 15 M, the volume of the second methanol aqueous solution container could be reduced.

(Example 5) The thickness L of the anode catalyst layer was set to 5
A direct methanol fuel cell power generator (Example 3) was obtained in the same manner as in Example 1 except that the thickness was 0 μm.
In the obtained fuel cell power generator, the flow rate J _m (mL / min) of the aqueous methanol solution defined by the above-mentioned formula (3)
The setting allowable range of is 0.13 ≦ J _m ≦ 1.0.

Further, the thickness L of the anode catalyst layer is set to 75 μm.
Directly in the same manner as in the first embodiment described above except that
A type methanol fuel cell power generator (Example 4) was obtained. Obtained
In the fuel cell power generator,
Flow rate of aqueous methanol solution J _m(ML / min) setting
Allowable range is 0.087 ≦ J_m≦ 0.69.

Further, the thickness L of the anode catalyst layer is set to 100.
A direct methanol fuel cell power generator (Example 5) was obtained in the same manner as in Example 1 except that the thickness was changed to μm. In the obtained fuel cell power generation device, the allowable setting range of the flow rate J _m (mL / min) of the aqueous methanol solution defined by the above-mentioned formula (3) is 0.065 ≦ J _m ≦ 0.52.

For the direct methanol fuel cell power generator of Example 3, the aqueous solution of methanol was supplied at a flow rate J _m of 0.4 mL /
It is supplied to the anode catalyst layer after making it min.
It was supplied to the cathode catalyst layer at a flow rate of L / min, and the voltage when a load current of 3 A was passed was measured. Figure 21 shows the measurement results.
Shown in. The abscissa of FIG. 21 represents the concentration C ⁰ _m (M) of the methanol aqueous solution initially put in the methanol aqueous solution container, and the ordinate represents the battery voltage (V). The initial concentration C ⁰ _m is 0.5
The voltage was measured for each concentration while varying within the range of ˜5M.

For the direct methanol fuel cell power generator of Example 4, the flow rate J _m was 0.3 mL / min, and for the direct methanol fuel cell power generator of Example 5, the flow rate J _m was 0.2 mL / min. Except for setting to min
The voltage when a load current of 3 A was applied was measured in the same manner as described in Example 3 above, and the measurement results are also shown in FIG.

From FIG. 21, the thickness L of the anode catalyst layer was set to 4
It can be seen that by setting the thickness to 0 μm or more, the direct methanol fuel cell can be driven over a wide range of the initial concentration C ⁰ _m of 0.5 to 5M. Further, similar to the experimental result shown in FIG. 17, the result was obtained that the voltage became higher as the initial methanol concentration C ⁰ _m became thinner. Further, as the thickness L of the anode catalyst layer becomes thinner, it is possible to obtain a voltage up to a lower concentration, and in the case of the anode catalyst layer thickness of 50 μm (Example 3), the limit becomes approximately 0.5M. Was confirmed. However, when the thickness of the anode catalyst layer is 50 μm, the influence of the crossover phenomenon becomes large. Therefore, when the flow rate J _m is increased to 0.4 mL / min, the voltage is increased in the region where the initial concentration C ⁰ _m exceeds 4 M. It was found that, in order to drive the fuel cell, the flow rate J _m needs to be slower than 0.4 mL / min within the range regulated by the above formula (3). From the viewpoint of reducing the influence of the crossover phenomenon, the initial concentration C ⁰ _m is 2 to 4
It is preferably within the range of M.

The limiting load current of the direct methanol fuel cell can be determined by the thickness of the anode catalyst layer and the concentration and flow rate of the methanol aqueous solution sent from the methanol aqueous solution container. Therefore, even if the output density of the battery changes depending on the electrolyte membrane, the catalyst or structure in the cathode catalyst layer, and the flow rate of the oxidizing agent, the relational expressions (1) to () defined in the direct methanol fuel cell power generation device according to the present invention. It is possible to apply 3).

(Embodiment 6) Without using the methanol aqueous solution recovery pipe 17 which is the methanol aqueous solution recovery mechanism, that is,
A direct methanol fuel cell power generator similar to that described in Example 1 was prepared except that the aqueous methanol solution discharged from the anode flow channel plate 6 was recovered through another route. In the obtained fuel cell power generator of Example 6, the setting allowable range of the flow rate J _m (mL / min) of the aqueous methanol solution defined by the equation (4) of the above-mentioned equation 7 was 0.015.
75 ≦ J _m ≦ 0.06190.

In the direct methanol fuel cell power generator of Example 6, the flow rate J of the aqueous methanol solution having a concentration of 3M was used.
Example 6 is a case where _m is 0.042 mL / min and is supplied to the anode catalyst layer, and air is supplied to the cathode catalyst layer at a flow rate of 200 mL / min. On the other hand, the concentration is 3M
Of methanol aqueous solution with a flow rate J _m of 0.168 mL / mi
n to supply to the anode catalyst layer, and 200 m of air
Example 7 is a case where the cathode catalyst layer is supplied at a flow rate of L / min. The measurement results of the current-voltage characteristics of Examples 6 and 7 are shown in FIG.

As is apparent from FIG. 22, the fuel cell power generation device of Example 6 in which the solution was fed at a low aqueous solution flow rate J _m of 0.042 mL / min resulted in a higher output density. It was This result is a result demonstrating FIG. 6 calculated to derive the relational expression (4) of the present invention. That is, when the flow rate J _m of the methanol aqueous solution supplied from the methanol aqueous solution container to the electromotive section is set within the range of the equation (4), the concentration of the methanol aqueous solution in the methanol aqueous solution container falls within the range of 2 to 5 M, and the output density It was confirmed that a peak appeared. This is explained by the increased power density due to the lower crossover overvoltage occurring in the cathode catalyst layer.

Further, the flow rate of the aqueous methanol solution J _{m is set} to 0.
Fixed at 042mL / min or 0.168mL / min, air flow rate 50mL / min, 100mL / m
in, 200 mL / min, 300 mL / min, 40
The change in the current-voltage characteristics when changing to 0 mL / min was measured. The results obtained are J _m when set at 0.042 mL / min in Figure 23, the J _m 0.168 mL /
FIG. 24 shows the result obtained when the value was set to min.

As is clear from FIG. 23, when the liquid feed amount J _m is 0.042 mL / min, the air flow rate is 200
It was possible to confirm that the output was saturated at mL / min. On the other hand, as is clear from FIG. 24, when the liquid feed rate J _m is 0.168 mL / min, the output is not completely saturated even when the air flow rate is increased to 400 mL / min, and The power density obtained at that time is J
It was found to be lower than when _m is 0.042 mL / min.

Therefore, from the results of FIGS. 22 to 24, Example 6 is obtained.
It can be understood that the direct type methanol fuel cell power generation device of (1) can realize the maximum value of the output densities obtained with a low air flow rate and a small amount of methanol aqueous solution feeding amount, and thus can obtain high energy conversion efficiency.

Furthermore, in the fuel cell power generators of Examples 6 and 7, when the fuel utilization efficiency η was calculated based on the following formula for the current density of 0.1 A / cm ² , the fuel of the fuel cell power generator of Example 6 was calculated. The utilization efficiency η was 82%, and the fuel utilization efficiency η of the fuel cell power generator of Example 7 was 20%. That is, according to the fuel cell power generator of Example 6, the fuel utilization efficiency η that is four times or more that of the fuel cell power generator of Example 7 can be realized, so that it is possible to eliminate the need to circulate the aqueous methanol solution on the anode side. .

Fuel utilization efficiency η = (10 ⁴ J) / (FCν ₁ ), where J is the current density (A / cm ² ), C is the concentration of methanol aqueous solution (M), and F is Faraday. It is a constant (96485 C / mol), and ν ₁ is the amount of methanol aqueous solution fed per unit area (ml / min / c).
m ² ).

Therefore, the concentration of the aqueous methanol solution should be 2-5M.
When the flow rate J _m of the aqueous methanol solution supplied from the aqueous methanol solution container to the electromotive section is set within the range of the above formula (4), the direct methanol fuel cell excellent in both energy conversion efficiency and fuel utilization efficiency is obtained. A power generator can be realized.

As a method of supplying an aqueous methanol solution as a fuel to the anode electrode of a direct methanol fuel cell, an internal vaporization method is known in addition to the method using a pump as described in the above-mentioned embodiment. There is. With the internal vaporization method, after introducing an aqueous methanol solution into the fuel permeation section by utilizing the capillary phenomenon, in the fuel vaporization section, the aqueous methanol solution is vaporized using the heat generated by the cell reaction in the electromotive section as the main heat source, The vaporized methanol aqueous solution is supplied to the anode.

However, when the fuel is supplied by the internal vaporization method, the amount of methanol fed per unit area per unit time is about 10 ml / min / cm ^2, and {N × (5. The value is about three orders of magnitude higher than the flow rate calculated from (2 / L) × S}. as a result,
In the fuel cell, a high output density can be obtained, but the output of the auxiliary device increases, so that the energy conversion efficiency becomes low. In addition, according to the internal vaporization method, methanol is continuously supplied to the anode electrode even while power generation of the fuel cell is interrupted, so that there is a problem that methanol crossover easily occurs.

[0147]

As described in detail above, according to the present invention, it is possible to provide a fuel cell power generator and an assembled battery in which the volume of the alcohol-containing aqueous solution container can be reduced and a high output can be obtained.

Further, according to the present invention, it is possible to provide a method of operating a fuel cell power generator capable of simultaneously satisfying energy conversion efficiency and output density.

Further, according to the present invention, it is possible to provide a fuel cell power generator and an assembled battery which are excellent in both fuel utilization efficiency and energy conversion efficiency.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a standard direct methanol fuel cell power generator.

FIG. 2 is a schematic diagram showing a separator as a flow path plate in the direct methanol fuel cell power generator of FIG.

FIG. 3 is a characteristic diagram showing a result of calculating a spatial methanol distribution in an electromotive section of a direct methanol fuel cell.

FIG. 4 shows the current-voltage characteristics of a direct methanol fuel cell,
Methanol concentration in the methanol solution container is 1M, 2
The characteristic view which shows the experimental result which changed and measured M, 5M, and 10M.

FIG. 5 is a characteristic diagram showing the result of calculating the dependence of the output density of the direct methanol fuel cell on the methanol concentration in the methanol aqueous solution container and the liquid supply flow rate.

6 is a characteristic diagram in which the calculation result of FIG. 5 is enlarged in a methanol concentration range of 5 M or less.

FIG. 7 is a characteristic diagram showing the results of calculation of the change in output density with respect to the concentration of methanol in a methanol aqueous solution container and the flow rate of liquid when the thickness of the anode catalyst layer is 40 μm.

FIG. 8 is a schematic diagram showing a main part of an example of a first direct methanol fuel cell power generator according to the present invention.

FIG. 9 is a circuit diagram showing an example of the configuration of a first direct methanol fuel cell power generator according to the present invention.

10 is a perspective view showing an anode electrode of the direct methanol fuel cell power generator of FIG.

FIG. 11 is a schematic diagram showing an example of a method for feeding an aqueous methanol solution when the electromotive portions of the direct methanol fuel cell power generator of FIG. 8 are stacked and connected in series.

FIG. 12 is a flow chart showing an embodiment of a first direct methanol fuel cell power generation device according to the present invention.

FIG. 13 is a circuit diagram showing an example of the configuration of a second direct methanol fuel cell power generator according to the present invention.

14 is a schematic diagram showing a main part of the direct methanol fuel cell power generator of FIG.

FIG. 15 is a flowchart showing an embodiment of a second direct methanol fuel cell power generator according to the present invention.

FIG. 16 is a circuit diagram showing an example of a configuration of an assembled battery according to the present invention.

FIG. 17 is a characteristic diagram showing measurement results in Example 1.

FIG. 18 is a characteristic diagram showing measurement results in Example 2.

FIG. 19 is a characteristic diagram showing another measurement result in Example 2.

20 is a characteristic diagram showing measurement results in Example 3. FIG.

FIG. 21 is a characteristic diagram showing measurement results in Example 5.

FIG. 22 is a characteristic diagram showing measurement results in Example 6.

FIG. 23 is a characteristic diagram showing the relationship between cell voltage, current density, and output density when the air flow rate is changed in the direct methanol fuel cell power generator of Example 6.

FIG. 24 is a characteristic diagram showing the relationship between cell voltage, current density, and output density when the air flow rate is changed in the direct methanol fuel cell power generator of Example 7.

[Explanation of symbols]

1 ... Anode current collector, 2 ... Anode catalyst layer, 3 ... Cathode current collector, 4 ... Cathode catalyst layer, 5 ... Electrolyte membrane, 6 ... Anode flow plate, 7 ... Methanol supply port, 8 ... Methanol outlet, 9 ... Anode channel, 10 ... Methanol aqueous solution container, 11 ... liquid feed pump, 12 ... Cathode channel plate, 15 ... Cathode channel, 16 ... Oxidizing agent supply means, 21 ... Fuel cell electromotive unit, 23 ... Auxiliary power source, 24 ... Methanol flow rate control device, 26 ... Current aging change recording device.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mitsuhiro Tomimatsu             1st Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa             Inside the Toshiba Research and Development Center (72) Inventor Masato Akita             1st Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa             Inside the Toshiba Research and Development Center (72) Inventor Yoshihiko Nakano             1st Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa             Inside the Toshiba Research and Development Center F term (reference) 5H026 AA08 CC03 CX05 HH03                 5H027 AA08 KK25 MM08

Claims (10)

[Claims] 1. An electromotive unit including at least one electromotive unit including an anode including an anode catalyst layer, a cathode, and an electrolyte membrane disposed between the anode and the cathode. A container containing an alcohol-containing aqueous solution, an anode channel for supplying the alcohol-containing aqueous solution to the anode electrode, and a surplus of the alcohol-containing aqueous solution supplied to the anode channel are collected in the container. The alcohol-containing aqueous solution is supplied from the container according to the alcohol concentration of the alcohol-containing aqueous solution in the container, which is evaluated from the recording mechanism of the alcohol-containing aqueous solution and the change in load current recorded as a change over time. ; and a flow control means for controlling the amount J _m (mL / min), the conditions shown in Equation 1 below (1) to (3) Fuel cell power plant characterized by foot. [Equation 1] Where C ⁰ _m is the initial alcohol concentration (M) of the alcohol-containing aqueous solution in the container, L is the thickness (μm) of the anode catalyst layer, and S is the reaction area (cm) of the anode catalyst layer. ² ), N represents the number of the electromotive unit in the electromotive unit. 2. An alcohol replenishment container for accommodating the alcohol-containing aqueous solution having a concentration higher than the initial alcohol concentration C ⁰ _{m, and} for replenishing the high-concentration alcohol-containing aqueous solution to the container, is further provided. Claim 1
The fuel cell power generator described. 3. At least one electromotive unit comprising an anode electrode including an anode catalyst layer having a thickness of 40 μm or more, a cathode electrode, and an electrolyte membrane disposed between the anode electrode and the cathode electrode. A fuel cell power generator comprising: an electromotive unit provided; and a container containing an alcohol-containing aqueous solution having an alcohol concentration of 2 M or more and 5 M or less, wherein the alcohol-containing aqueous solution supply amount J _m (mL
/ Min) is within the range defined by the following equation (4), the fuel cell power generator. [Equation 2] However, L is the thickness (μm) of the anode catalyst layer,
S is a reaction area (cm ² ) of the anode catalyst layer,
The N indicates the number of units of the electromotive unit in the electromotive unit. 4. Further comprising a pump connected to said container
Provision, the supply amount J _m(ML / min) is the pump
Is equal to the amount of liquid sent per unit time (minute) of
The fuel cell power generator according to any one of claims 1 to 3. 5. A plurality of pumps connected to the container are further provided, and the supply amount J _m (mL / min) is a sum of the liquid supply amount per unit time (minute) of each pump. The fuel cell power generator according to claim 1, wherein the fuel cell power generator is a fuel cell power generator. 6. A set comprising: the fuel cell power generation device according to claim 1; and a non-aqueous electrolyte secondary battery electrically connected to the fuel cell power generation device. battery. 7. At least one electromotive section unit comprising an anode electrode including an anode catalyst layer having a thickness of 40 μm or more, a cathode electrode, and an electrolyte membrane disposed between the anode electrode and the cathode electrode. An electromotive unit provided, a container containing an alcohol-containing aqueous solution having an initial alcohol concentration in the range of 2M to 5M, an anode flow channel for supplying the alcohol-containing aqueous solution to the anode electrode, and the anode flow channel. From the alcohol-containing aqueous solution recovery mechanism that recovers the surplus of the supplied alcohol-containing aqueous solution in the container, and the one in which the load current is recorded as a change with time corresponding to the operating time, the alcohol concentration of the alcohol-containing aqueous solution in the container is determined. A method for operating a fuel cell power generator comprising an alcohol concentration evaluation mechanism for evaluating and calculating an evaluation concentration, wherein: When valence concentration is in the range of 2M～5M, alcohol-containing aqueous solution feed amount J _m from the vessel (mL / mi
a first power generation step of obtaining electric power from the fuel cell power generation device by maintaining n) at a constant value within the range of the formula (3) below, and when the evaluation concentration drops below 2M, Supply amount J
Secondly, to obtain electric power from the fuel cell power generator by increasing _m (mL / min) within the range of the formula (3).
The method for operating a fuel cell power generation device, comprising: [Equation 3] However, L is the thickness (μm) of the anode catalyst layer,
S is a reaction area (cm ² ) of the anode catalyst layer,
The N represents the number of units of the electromotive unit in the electromotive unit. 8. The method further comprises an alcohol replenishing step of increasing the evaluation concentration to 0.5 M or more by replenishing the container with an alcohol-containing aqueous solution when the evaluation concentration drops below 0.5 M. The method for operating a fuel cell power generator according to claim 7. 9. In the alcohol replenishment step, while the second power generation step is performed, the evaluation concentration is 0.5 M or more, 2
9. The method for operating a fuel cell power generator according to claim 8, wherein the operation is performed until it becomes less than M. 10. The alcohol replenishment step is performed in parallel with the second power generation step until the evaluation concentration becomes 0.5 M or more and less than 2 M, and when the evaluation concentration reaches 2 M, the second The power generation process of No. 1 is switched to the first power generation process, and the evaluation concentration is 5 while performing the first power generation process.
9. The method for operating a fuel cell power generator according to claim 8, wherein the operation is performed until M is reached.