JPS6068561A - Electrolyte supplement equipment of matrix type fuel cell - Google Patents

Abstract

PURPOSE:To provide electrolyte supplement equipment of matrix type fuel cell which can surely supplement electrolyte even if fuid resistance in an electrolyte supplement path of a cell is varied. CONSTITUTION:A pressure vessel 21 is incorporated in a manifold cover 11 which supplies reaction gas, for example, fuel gas F for a cell stack 10 formed by stacking a large number of unit cells 1. Electrolyte is supplemented by changing a cross electromagnetic valve to connect a pressure pipe 31 to a piece 38. By this operation, when the pressure of a pressure gas source N is increase by several tens mm.Hg than that of reaction gas, the pressure in the pressure vessel is increased by a specified value than that of reaction gas, and electrolyte stored in an electrolyte vessel 22 is supplemented at one time through electrolyte supplement tubes 23.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an electrolyte replenishing device for a matrix fuel cell formed by stacking a plurality of unit cells including a porous matrix layer as an electrolyte holder.

[Problems with conventional technology]

In the above-mentioned matrix type fuel cell, a fuel gas electrode 1, for example, a hydrogen electrode, to which fuel gas is supplied and which maintains an anode reaction, and an oxidizing gas An oxidizing gas electrode 1, for example an air electrode, is arranged which is supplied and maintains the cathodic reaction.

These constitute a unit cell as a power generation element, but in order to continuously supply the reactant gas, that is, fuel residue and oxidant gas to both the fuel and oxidation electrodes mentioned above, the reactant gas is passed through the electrode itself. Either grooves are cut to separate the fuel gas section and the oxidizing gas section when a plurality of unit cells are stacked, or grooves are provided in the separator plate interposed between the unit cells to separate the fuel gas section and the oxidizing gas section.

The former will be referred to as a grooved electrode structure, and the latter will be referred to as a grooved separator plate structure.

On the other hand, the electrolyte dissolved in the electrolyte or the electrolyte used as the electrolyte is generally a substance that undergoes few chemical changes and is less likely to decrease due to evaporation, etc. 2 For example, phosphoric acid is used, but it is important to avoid long-term battery operation. Although there is only a small amount of electrolyte in the battery, it is unavoidable that the electrolyte will be lost from the inside of the battery, and some means must be taken to replenish the electrolyte or electrolyte.

In order to replenish the matrix with electrolyte that is gradually being lost, a server is often provided to store the electrolyte within the cell or its 84 unit.

For example, in the case of the above-mentioned grooved electrode structure, this node is provided inside the electrode, and in the case of the grooved separator plate structure, it is provided on the separator plate, but it must be provided within the limited space inside the battery. Therefore, there is a limit to the amount of electrolyte that can be stored, and in the case of a grooved electrode structure, the gas diffusion function of the electrode made of a porous material is hindered to some extent by providing a reservoir.

In order to solve the problem of electrolyte replenishment, it is necessary to overcome the above-mentioned drawbacks and to develop an electrolyte replenishment device that satisfies the following requirements.

(at If the electrolyte supply route to each cell is common,
Since a so-called liquid junction occurs between the cells through the electrolyte, the electrolyte supply paths to each cell must be separated or electrically insulated from each other as much as possible.

+bl When operating a battery for a long period of time, it is necessary to prevent leakage from the electrolyte supply path.

tc+ The viscosity of the electrolyte tends to change considerably when the temperature changes, and if air bubbles are mixed into the electrolyte, the apparent viscosity or fluid resistance will change, so even if the fluid resistance changes slightly, it will not cause yellowing. Must be able to replenish.

In particular, the fc1 term is when trying to reduce the external dimensions of the battery stack by making the electrodes or separator plates as thin as possible.
Since the cross-sectional area of the electrolyte replenishment path is naturally reduced accordingly, this is a factor that poses a considerable hindrance to the development of a highly reliable electrolyte replenishment device ζ.

[Purpose of the invention]

An object of the present invention is to take into consideration the above-mentioned drawbacks, and to ensure that even if the fluid resistance in the electrolyte replenishment path inside the battery changes,
The object of the present invention is to obtain an electrolyte replenishing device for a matrix type fuel cell that can replenish iH solution.

[Key points of the invention]

In order to achieve the above object, the present invention
An electrolytic solution container for storing electrolyte to be replenished to the battery is provided outside the two-cell stack, and a sufficient amount of electrolyte necessary for replenishment is stored. Since this container is provided for each stack level of the batteries in the battery stack, liquid junctions through the electrolyte between the stack units are prevented. The laminated unit does not necessarily have to be a single cell, but may be a unit in which several single cells are laminated as long as liquid junction is allowed.

Next, the electrolyte containers are stored in a pressurized container, which is a four-pack box that forms a compartment isolated from the reaction gas supplied to the fuel cell, and is electrically insulated from each other. do. Further, the electrolyte in the electrolyte container Q) is preferably supplied to the valley cell to which the electrolyte is to be replenished from the electrolyte container via an electrolyte replenishment tube consisting of one continuous tube. By connecting the inside θ) to the liquid replenishment path and increasing the scum pressure in the pressurized container by a pressurizing means to a slight degree higher than the reaction scum Q) pressure inside the battery,
The electrolyte in the electrolyte container 17 is pushed out and supplied to the electrolyte supply path of each unit cell through the electrolyte supply tube.

The electrolyte in the matrix layer oozes into the gas-diffusion electrode in contact with it, and is always under a pressure balanced with the pressure of the reaction gas within the electrode, so it can flow into the pressurized container mentioned in i. It is unwise to raise the pressure significantly higher than the reaction pressure within the battery (GAo) without significantly disturbing the pressure balance within the battery, and to ensure that the electrolyte is replenished. Since the pressure is about several tens of millimeters of water column,
The pressurization by the above-mentioned pressurizing means must be controlled quite strictly so that the differential pressure becomes a predetermined value of this order.

In the electrolyte replenishment device according to the present invention configured as described above, it is possible to maintain the pressurized state of the pressurized container at all times so that the electrolyte is constantly replenished into the battery. Although this is possible, the rate at which the electrolyte escapes from the battery is extremely slow, so it is usually sufficient to replenish the electrolyte by intermittently pressurizing the pressurized container. In such case,
After maintaining the pressurized state of the pressurized container for a predetermined period of time, the pressure inside the pressurized container is returned to a controlled state equal to the pressure of the reaction gas within the battery. In this way, when replenishing the electrolyte,
d The electrolyte in the solution supply path is energized to a pressure higher than the pressure of the reaction scum in the battery by a predetermined value, so the fluid resistance to the electrolyte in the supply path is reduced by temperature changes, air bubbles, etc. Replenishment will be ensured even if it varies slightly depending on the cause.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the main part of the electrode base material 3a of the electrode 3 used in a battery with a ribbed electrode structure. As shown in the figure, a large number of grooves 3C are cut, and reaction scum flows through these grooves. It will be done. Electrolyte replenishment grooves 3d and 3e are cut in the edge portion of the electrode base material 3a parallel to the grooves, and an electrolyte replenishment tube 23 is fitted into the groove 3e of these grooves, and an electrolyte replenishment tube 23 is inserted into the groove 3e. An adhesive 23a9 having acid number and corrosion resistance is bonded to the groove 3e by, for example, a Teflon adhesive, and the adhesive 23a
Therefore, the groove 3d is liquid-tightly sealed from the outside of the battery.

As shown in the figure, a communication hole 3f is formed at the bottom of the groove 3d, and serves to communicate the electrolytic solution in the groove 3d with a matrix layer to be described later. Note that since the electrode base material 3a is made of a gas diffusive material 1, for example, a porous graphite material, a liquid-repellent Teflon-based material is infiltrated into the peripheral walls of the grooves 3a and 3e, and the grooves 3d , 3e to prevent unnecessary penetration of the electrolytic solution into the electrode base material 3a.

On the right side of FIG. 2, a partial uJr surface of the battery stack 10 including the electrode substrate 3a having such an electrolyte supply path is shown. In the figure, a portion indicated by the reference numeral 1 represents one unit cell, and each unit cell 1 includes a matrix layer 2, a fuel gas electrode 3, and an oxidizing gas electrode 4. Furthermore, each electrode 3
, 4 are electrode substrates 3a, 4a and catalyst layer 3b, respectively.
, 4b, each of the electrode substrates 3a and 4a has grooves for reactant gas on the curves on the opposite side from the Tx layer 2. Illustrated electrode substrate 4a on the oxidizing gas side
As is well known, the groove 4C is cut in a direction perpendicular to the groove 3C of the electrode substrate 3a on the fuel gas side.

These unit cells 1 are stacked together with a gasket 6 disposed on the periphery through an airtight separator plate 5 to form the above-mentioned battery stack 1O.

The aforementioned grooves 3d and 3e' serve as electrolyte replenishment paths for replenishing electrolyte to each cell 1! 6 and the communication hole 3f, the electrolyte E stored in the electrolyte container 22 housed in the pressurizer 21 shown partially in cross section on the left side of FIG. is communicated with. For this reason, the electrolyte supply tube 23 penetrates the container wall 21a of the pressurized container via an airtight seal 23b, and its end portion 23c opens near the bottom surface of each electrolyte container 22. It is preferable to use one continuous tube for each cooling liquid replenishment tube in order to prevent liquid leakage, and since the material is required to have corrosion resistance against electrolyte 2, such as phosphoric acid, for example, Teflon, etc. Tubes are preferred and their flexibility is advantageous in routing the tubes.

Each electrolyte container 22 is preferably made of an insulating material that has corrosion resistance to the electrolyte and electrically insulates each other.
For example, Teflon moldings are suitable for phosphoric acid electrolytes. Of course, the cough containers do not necessarily have to be electrically insulating, but may be insulated from each other by other appropriate means. As shown in the figure, the container 22 is provided with an opening 22a through which the electrolyte replenishment tube 23 is inserted.If possible, another opening 22b may be provided to communicate with the space inside the pressurized container 21. Convenience in charging the container 22 with electrolyte is provided. These electrolyte containers 22 are fixedly or fixedly placed on the shelf 2Ib provided with the communication hole 2C of the pressurized container 21 by appropriate means (not shown).

FIG. 3 shows an embodiment in which a pressurized vessel 21 is integrated into a manifold section for supplying reactant gases of a fuel cell. In the figure, a supply manifold lid for supplying reactive gas, for example, fuel gas F from the left side of the figure, is provided on both left and right sides of the battery stack 10 formed by stacking a large number of unit cells 1. 11 and an exhaust manifold lid 12 for collecting reaction gas exhausted from the battery. In the illustrated embodiment, a pressurized container 22 is fixedly incorporated into these meat supply side manifold lids 11. Of course, manifold covers are similarly attached to the front and back sides of the battery stack 10, but they are omitted from the figure for the sake of simplicity.

Note that these battery stack 10 and manifold lid],
1, 12, etc. are pressure vessels 1 indicated by dashed lines in the figure.
As is well known, it is common to be housed in the 3. The fuel gas F or oxidizing gas A1, for example, air, is supplied to the fuel cell stack 10 through an inlet pipe 1 ], a which penetrates the manifold lid 11 from the outside, and these reaction scum F or A are supplied. Side manifold section 11
The remaining portion enters the battery stack 10 from the above-mentioned groove 3C or 4C and is not consumed within the battery. is discharged outside.

The pressurizing gas is introduced into the pressurizing container 21 by
In the figure, it is carried out through the pressurizing pipe 31 shown at the bottom,
Inert gas for pressurization.

For example, nitrogen is preferred from a safety standpoint. The pressurizing system 30 as a pressurizing means in the present invention is shown below the θ) 71+1 pressure 31, and includes three-way solenoid valves 32, 33, and regulating valves 34. Differential pressure detector 35. A differential pressure regulator 36 is included.

First, when not replenishing the electrolyte, the three-way 't (L 1
The pressure inside the 1fi pressure vessel 21 is the pressure inside the manifold 11.

In other words, the pressure is equal to that of the reaction scum.

To start replenishing the electrolyte, switch the three-way solenoid valve 32 to connect the pressurizing pipe 31 with the piping 37 shown in the figure, and connect the three-way solenoid valve 33 to connect the piping 37 with the piping 38 from the pressurized gas source N. Resistant to the position where it communicates with. As a result, if the pressure of the pressurized gas source N is set in advance to a pressure several tens of millimeters of water column higher than the pressure of the reaction scum as described above, the pressure inside the pressurized container 21 can be reduced by a predetermined value to the pressure of the reaction gas. The electrolytic solution stored in the electrolytic solution container 22 can be supplied to each unit cell 1 at the same time via the electrolytic solution replenishment tube 23. Of course, in this case, the pipe 38 may be directly connected to the three-way solenoid valve 37 instead of the pipe 37, and the installation of the three-way solenoid valve 33 is not particularly necessary.

The purpose of electrolyte replenishment is usually achieved by the above-mentioned replenishment means, but if a large amount of air bubbles accidentally get mixed into the electrolyte replenishment channel or the electrolyte replenishment tube inside the battery, the fluid resistance becomes extremely high. If the temperature of the electrolyte is low and its viscosity is extremely high when restarting a battery that has been out of operation for a while, it may not be possible to replenish the electrolyte smoothly using only the above-mentioned methods. could be. Replenishment means in such a case will be described below as different embodiments of the present invention with reference to FIGS. 3 and 4.

On the left side of FIG. 4, there is shown in cross section a side portion of the cell which is opposite to that shown in FIG. This sectional view is almost the same as FIG. 2, but the sole layer 7 is provided so that the edge seal shown as the gasket 6 in FIG. The one thing that has been replaced is slightly different. The communication hole 3f passes through this seal shield 7 and communicates with the matrix layer 2, showing a slightly different aspect of the electrolyte supply path. Now,
The groove 3 is connected to the groove 3d as an electrolyte supply path.
A tube 24 leading to an electrolyte reservoir 25 for temporarily storing the electrolyte in d is led out from the side of the battery at $111 on the right in the diagram. Further, the electrolytic solution d 25 is installed at a position several tens of millimeters higher in the water column than the electrolyte g 3 d.

When the electrolyte replenishment starts, the three-way solenoid valve is activated so that the pressurized gas from the pressurized gas source N is introduced into the pressurized container 21 via the pipes 38 and 37 and the pressurized pipe 31 as described above. 32
．． 33 is operated, but the pressure of the pressurized gas source is selected to be slightly higher than the above-mentioned regular predetermined value, and the electrolyte is introduced into the groove 3d by overcoming the high fluid resistance in the electrolyte supply path. so that However, in this case, since the groove 3d is in communication with the electrolyte reservoir 25, the electrolyte that was initially in the groove 3d flows toward the electrolyte reservoir 25 before moving toward the matrix layer 2. It is pushed out and temporarily stored there. As a result, the highly viscous or bubble-containing electrolyte in the groove or electrolyte replenishment tube 23 is temporarily removed to the electrolyte reservoir, and new replenishing electrolyte is filled in the groove 3d.

The three-way solenoid valve 33 is then switched to communicate the pipe 37 with the pipe 39 containing the regulating valve 34.

In this state, the differential pressure detector 35 starts operating and detects the differential pressure between the reaction gas supply pipe 14 (its branch pipe 14a in the figure) and the outlet pressure of the regulating valve 34, and the differential pressure regulator 34 detects the differential pressure. In response to the differential pressure detected by the pressure detector, the differential pressure increases the electrolyte (IJ)
The control valve 34 is controlled to a convenient predetermined value for replenishing the stock layer 2. After this desired state is maintained for a short time, the three-way solenoid valves 32 and 33 are returned to the state before the start of replenishment so that the pressure of the reaction scum is introduced into the pressurizing pipe 31 as described above. Thereafter, the electrolyte temporarily stored in the electrolyte reservoir 25 returns to the groove 3d, and if the amount is excessive, it flows back through the electrolyte supply tube 23 and enters the electrolyte container 22. As shown in FIG. 4, the electrolyte reservoir 25 is secured to the support member 26 by a suitable stopper 25a.
It is reasonable to fix this to the manifold compartment 12b of the manifold lid 12 in FIG. Further, it is preferable that the upper part of the electrolytic solution reservoir 25 is opened into the manifold section 12b so that air bubbles contained in the temporarily stored electrolyte solution can be diffused into the manifold section. However, it is not necessary to provide such an electrolyte reservoir; for example, an electrolyte container similar to that shown in FIG. 2 may be provided in the manifold section 12I) in a manner similar to that shown in FIG. .

The electrolyte replenishing device according to the present invention, which is not limited to the embodiments described above, can be implemented in various ways within the scope of the present invention. For example, as shown in Fig. 3, it is not necessary to introduce the reaction gas itself into the pressure tube in order to balance the pressure in the pressurized container with the pressure of the reaction gas before and after replenishing the electrolyte. Instead, the objective of pressure equalization can be easily achieved using various known means.

[Effect of investigation]

As described above, the electrolyte replenishing device for a matrix fuel cell according to the present invention can sufficiently achieve the intended purpose with a relatively simple configuration as seen in the gist of the present invention. In other words, by pressurizing the edge pressure vessel to an appropriate value using zero-pressure means, it is possible to replenish electrolyte at an appropriate pressure from the electrolyte container housed in the pressurized vessel to each MiL battery in the battery. Therefore, even if the electrolyte undergoes a change in viscosity or fluid resistance due to a change in temperature or the inclusion of air bubbles, the purpose of replenishing the electrolyte can be reliably achieved. Furthermore, since the electrolyte containers are always kept insulated from each other, there is no risk of a liquid junction occurring between the cells or the battery stack unit through the electrolyte, and high battery transport efficiency is ensured.

According to the present invention, electrolyte replenishment can be carried out smoothly even under some adverse conditions, and there is no need to provide an electrolyte reservoir inside the battery, which requires a considerable amount of space as in the past. For both ribbed separator plate structures, the thickness of the electrode substrate and the separator plate can be drastically reduced, making it possible to reduce the external dimensions of the battery. Furthermore, since reliable electrolyte replenishment can be achieved even if the cross-sectional area of the electrolyte replenishment path is reduced, the conventional constraints on the size reduction of the laminated twin battery system from the aspect of electrolyte replenishment are essentially eliminated. , it is possible to drastically rationalize this battery structure. Furthermore, since the electrolyte container according to the present invention is housed in a pressurized container with a closed structure necessary for pressurization, completely isolated from the reaction gas, the possibility of troubles caused by electrolyte leakage can be extremely reduced. can.

[Brief explanation of drawings]

The drawings all show embodiments of the device of the present invention, and FIG. 1 is a perspective view showing the main part of the electrode substrate of a fuel cell in which an electrolyte replenishment path is provided, and FIG. FIG. 3 is a partial cross-sectional view and system diagram showing the entire electrolyte replenishment device according to the present invention in combination with the battery main body; FIG. 4 is a sectional view showing a main part of a different embodiment of the device of the present invention. In the figure, 1:
Cell, 2: Matrix layer, 3d, 3e: Groove as electrolyte supply path, 3f: Communication hole through electrolyte supply path, 1
0: Battery laminate, 21: Pressurized container, 22: Electrolyte container,
23: Electrolyte supply tube, 25: Electrolyte reservoir, 30:
Pressurizing means, 31: Pressurizing pipe, 32, 33: Three-way solenoid valve as pressurizing means, 34: Control valve as pressurizing control means, 3
5: Differential pressure detector as pressurization control means, 36: Differential pressure regulator as pressurization control means, 37, 38, 39: Piping as pressurization means, A: Oxidizing gas as reaction scum, E: Electrolytic solution, F: fuel scum as reaction scum, N: pressurized gas source. jC -it (2) Continuing from page 1 of O-Zaki ■Inventor Nakajima Noriyuki Masukasho

Claims (1)

[Scope of Claims] d) A porous matrix layer serving as an electrolyte holder; A device for replenishing electrolyte to a battery stack made of an electrolytic solution which is housed in a mutually electrically insulated state and each has an opening that opens to the inner compartment of the container, is provided for each stacked unit of batteries in the battery stack, and is to be replenished to each unit; a plurality of electrolyte containers for storing the electrolyte, an electrolyte replenishment tube that connects the electrolyte in each electrolyte container to the electrolyte replenishment path of the unit cell, and An electrolyte replenishing device for a matrix fuel cell, comprising: pressurizing means for controlling the pressure inside the pressurized container so that it is higher than the pressure of the reactant gas within the pressurized container by a predetermined value. 2. An electrolyte replenishing device for a matrix fuel cell according to claim 1, wherein the pressurized container is housed in a manifold section for supplying reaction gas to the fuel cell. 3) An electrolyte replenishing device for a matrix fuel cell according to claim 1, wherein an inert gas is used as pressurizing gas to the pressurized container. 4) The apparatus according to claim 1, wherein the pressurizing means intermittently pressurizes the pressurized container for replenishing the electrolyte to the fuel cell. Device. 5) An electrolyte replenishing device for a matrix fuel cell according to claim 4, wherein the pressurizing means pressurizes the pressurized container for a predetermined period of time during electrolyte replenishment. 6) In the device according to claim 4, the electrolyte replenishment path in the fuel cell has openings on two different side surfaces of the battery stack, and one of the openings is used for electrolysis. The electrolyte is connected to the electrolyte in the electrolyte container via the liquid replenishment tube, and the other opening is located above the opening to temporarily store the electrolyte while communicating with the electrolyte replenishment path. An electrolyte replenishment device for a matrix fuel cell, which is characterized by the connection of a reservoir. 7) In the device according to claim 6, the electrolyte reservoir is housed in a manifold section for supplying reaction gas to the fuel cell, and the liquid level in the electrolyte reservoir is open to the reaction gas in the manifold. An electrolyte replenishment device for an IJ type fuel cell. 8) The apparatus according to claim 4, wherein the pressurizing means controls the pressure in the pressurized container to be equal to the pressure of reaction scum in the fuel cell after replenishing the electrolyte. Electrolyte replenishment device for fuel cells. 9) An electrolyte replenishing device for a matrix fuel cell according to claim 1, wherein each electrolyte replenishing tube is comprised of one continuous flexible Teflon tube. 10) An electrolyte replenishing device for a matrix fuel cell, wherein the electrolyte container is made of an electrically insulating material.