JPH04274174A - Fuel cell - Google Patents

Abstract

PURPOSE:To achieve load fluctuation operation at a good responsiveness by providing through-holes of corresponding forms to each other in a shutter plate and a collector plate disposed in contact with each other, and changing a through aperture area by the through-holes. CONSTITUTION:A fuel oxidation electrode 3 and an air reduction electrode 5 are provided with a shutter 7 having a number of through-holes 6 and a collector plate 10 having through-holes 8 of the same pitch and the same area as the through-holes 6 in the shutter plate 7 respectively. The shutter plates 7, 7 are movable up and down. A through aperture area formed by the through- holes 6 in the shutter plate and the through-holes in the collector plate 10 is changed by vertical motion of the shutter plate 7, so a passing quantity of fuel such as methanol or air can be controlled. When a cell reaction is stopped, by setting the through-hole area between the through-holes 6, 8 at zero, diffusion of fuel through an electrolyte chamber 12 to an air reduction pole 5 is eliminated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell, and more particularly to a fuel cell that is highly responsive to load fluctuations.

0002

[Prior Art] A fuel such as methanol is supplied to a negative electrode (hereinafter referred to as a fuel oxidation electrode), and air is supplied to a positive electrode on the opposite side of the negative electrode (hereinafter referred to as an air reduction electrode) via an electrolyte. . At the fuel oxidation electrode, supplied fuel such as methanol reacts with water to generate CO2 gas, protons, and electrons. Electrons generated at the fuel oxidation electrode are supplied to the load side via a current collector plate.

[0003] Further, in the air reduction electrode, water is produced by electrons supplied to the air reduction electrode via a load, protons supplied from the electrolyte, and air.

[0004] By electrochemically performing the combustion reaction of fuel such as methanol, the free energy change accompanying the oxidation reaction can be directly extracted as electrical energy.

FIG. 5 shows a detailed diagram of each of the electrodes. In the figure, adjacent to the fuel chamber 32, there is a fuel oxidation electrode 33 consisting of a current collector 39, a gas supply layer 33a of gaseous fuel, and a fuel oxidation reaction layer 33b, and an air chamber 37 is also located. Similarly, the current collector 39, the gas supply layer 36a, and the air reduction reaction layer 36
An air reduction electrode 36 consisting of an electrode 33 and b is adjacent to each other, and an electrolyte chamber 35 is located between these two electrodes 33 and 36. The current collector 39 is made of a mesh-like metal material. Both electrodes 33, 36
The gas supply layers 33a and 36a are provided to prevent fuel such as methanol from directly reaching the reaction layers 33b and 36b.
Consists of carbon clusters of Å. Also, both electrodes 3
The reaction layers 33b and 36b of 3 and 36 are regions in which gaseous fuel or air reacts, and are wetted with the electrolyte (containing, for example, sulfuric acid water at a concentration of several tens of percent) in the adjacent electrolyte chamber 35. In order to improve the properties, for example, hydrophilic carbon is formed into clusters. Further, the reaction layer 33b on the side of the fuel chamber 32 includes a fuel oxidation reaction catalyst,
For example, an alloy of Pt and Ru is contained, and the reaction layer 36b on the side of the air chamber 37 contains a catalyst for air reduction, such as Pt.

Gas supply layer 33a of each electrode 33, 36
, 36a have a function of supplying gasified methanol or oxygen gas, a function of discharging gas generated by the cell reaction in the reaction layers 33b and 36b, and a function of preventing electrolyte from leaking to the fuel chamber 32 side. In addition, reaction layers 33b and 36
b contains a catalyst and has the function of causing a battery reaction.

[0007]

SUMMARY OF THE INVENTION The conventional backside fuel supply type fuel cell described above is capable of steady operation, but has a problem in that it cannot cope with load fluctuation operation. Conventionally, as a countermeasure against this load fluctuation, it has been considered to control the concentration and amount of fuel to be supplied, but there are problems with the accuracy and responsiveness of the above control, and problems such as increasing the size of auxiliary equipment remain. .

[0008]Furthermore, fuel such as methanol is used in the electrolyte chamber 35.
There is also the problem that the air passes through the air and diffuses into the air reduction electrode 36. In particular, when the battery reaction is stopped, a large amount of fuel diffuses into the electrolyte chamber 35, which may cause problems such as deterioration of battery performance and heat generation during startup.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel cell that can operate with load fluctuations with good responsiveness and completely shuts off the electrolyte permeability of the fuel when the cell reaction is stopped.

0010

[Means for Solving the Problems] The above objects of the present invention are achieved by the following configuration. That is, a fuel chamber equipped with a fuel supply/discharge path for supplying and discharging fuel to the fuel oxidation electrode;
In a fuel electrode, an air chamber is provided with an air supply/discharge path for discharging air after supplying air to the air reduction electrode, and an electrolyte chamber is provided between the fuel oxidation electrode and the air reduction electrode, each of which is provided with a current collector plate. Alternatively, a slidable shutter plate having a plurality of through holes is provided at at least one of the boundaries between the air chamber and the electrode adjacent to each of the chambers, and the current collector plate includes the shutter plate. The fuel cell is characterized in that the number of through holes corresponding to each of the plurality of through holes is formed in the same number as the through holes of the shutter plate, and the through holes are arranged in contact with the shutter plate.

The shutter can be driven using hydraulic pressure, an electric motor, an ultrasonic motor, a piezoelectric element that utilizes distortion caused by voltage changes, an electromagnet, a bimetal, a shape memory alloy, or the like. In addition, the diameter of the through-holes in the shutter plate and the current collector plate should be several millimeters. Further, the material of the shutter plate is preferably a corrosion-resistant material such as stainless steel or fluororesin, and sufficient controllability can be ensured by setting the thickness to several millimeters or less.

Furthermore, in order to maintain the rigidity of the shutter plate, the shutter plate may be sandwiched between two collector plates provided with through-holes.

[0013]

[Operation and Effects of the Invention] When the shutter plate is slid, the area of the through-hole through which fuel or air can flow, which is formed between the through holes of the plurality of through holes provided in each of the shutter plate and the current collector plate, is increased. The amount of fuel supplied to the fuel reaction layer of the electrode or the amount of air supplied to the air reaction layer of the electrode can be controlled with good responsiveness. Further, when the battery reaction is stopped, the area of the through-holes formed by the through-holes of the shutter plate and the current collector plate is reduced to zero, thereby eliminating the possibility that fuel will diffuse into the air reduction electrode via the electrolyte chamber.

[0014] In this way, by providing through holes in the shutter plate and the current collecting plate and changing the area of the through-holes formed by the through holes in both, the amount of fuel and air supplied can be controlled arbitrarily, so that changes in the load of the cell reaction can be achieved. Good responsiveness.

Furthermore, by reducing the area of the through-hole to zero when the battery reaction is stopped, there is no fear that the fuel will diffuse toward the air reduction electrode, causing deterioration in battery performance, heat generation, etc.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described with reference to the drawings. Example 1 A vertical cross-sectional view of a fuel cell 1 is shown in FIG. 1, and a side cross-sectional view on the fuel chamber side of FIG. 1 is shown in FIG. A shutter 7 having a large number of through holes 6 in the fuel oxidation electrode 3 and the air reduction electrode 5, and a current collector plate 10 having through holes 8 having the same pitch and the same area as the through holes 6 of the shutter plate 7 are provided.

An electrolyte chamber 12 is provided between both current collector plates 10, 10 with a gas supply layer and a reaction layer 11 interposed therebetween. Each shutter plate 7, 7 can be moved up and down by a motor 16 (FIG. 2) via a cam 15 located in the fuel cell lower chamber 14. At this time, motor 1
A one-way clutch 19 is connected to the connecting shaft 18 between the 6 and the cam 15.
By providing this, the cam 15 can be rotated in only one direction, and the shutter plate 7 can be held halfway even when the motor 16 is turned off. As the shutter plate 7 moves up and down, the area of the through-hole formed by the through-hole 6 of the shutter plate 7 and the through-hole 8 of the current collector plate 10 changes, so that, for example, the amount of fuel such as methanol or air passing through is changed. It becomes possible to control the

Furthermore, when the battery reaction is stopped, the through hole 6
, 8 eliminates the possibility that the fuel will inadvertently pass through the electrolyte chamber 12 and diffuse into the air reduction electrode 5. Note that the end of the shutter plate 7 is sealed with a fuel cell wall sealant 20. Further, the left half of FIG. 2 shows the state when the penetrating opening is open, and the right half shows the state when the penetrating opening is closed.

Example 2 FIGS. 3 and 4 show the fuel cell 1 of this example. In this embodiment, a partition wall 23 having a large number of through holes 22 is provided at the boundary between the fuel chamber 21 and the fuel oxidizing electrode 3, and a rotatable shutter plate 25 is provided with a central axis supported by the partition wall 23. This shutter plate 25 is also formed with pores 26 having the same pitch and the same area as the pores 22 of the partition wall 23. The shutter plate 25 has an extended rack portion 27 driven by a motor 29.
Rotated at 0.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a fuel cell according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the fuel cell of FIG. 1 seen from the front.

FIG. 3 is a sectional view of a fuel cell according to another embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of the fuel cell of the embodiment shown in FIG. 3, seen from the front.

FIG. 5 is a detailed diagram of each electrode of the fuel cell.

[Explanation of symbols]

3 Fuel oxidation electrode 5 Air reduction electrode 7 Shutter board 10 Current collector 6, 8, 22, 26 Pore 7, 25 Shutter board

Claims (1)

[Claims] Claim 1: A fuel chamber equipped with a fuel supply/discharge passage for supplying and discharging fuel to a fuel oxidation electrode, and an air chamber equipped with an air supply/discharge passage for supplying and discharging air to an air reduction electrode. , in a fuel electrode in which an electrolyte chamber is provided between a fuel oxidation electrode and an air reduction electrode, each of which has a current collector plate, at least one of the boundaries between the fuel chamber or the air chamber and an electrode adjacent to each chamber; is provided with a slidable shutter plate having a plurality of through holes formed therein, and the current collector plate is provided with a through hole having a shape corresponding to each of the plurality of through holes of the shutter plate. A fuel cell, characterized in that the same number of fuel cells are formed and arranged in contact with the shutter plate.