JP2906241B2 - Liquid flow type electrolytic cell - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid flow type electrolytic cell used for a redox flow type battery or the like, and more particularly, to a liquid electrode type electrolytic cell using a porous electrode material such as a carbonaceous fiber aggregate. The present invention relates to a liquid flow type electrolytic cell having a formed three-dimensional electrode.

(Related Art) A redox flow battery, which is a kind of rechargeable chemical battery, is known as a battery for storing surplus electric power at night and releasing it when daytime demand increases to respond to fluctuations in demand. ing. The redox flow battery is also being developed as a backup device for power generation using natural energy such as sunlight, wind, and wave power, or as a power source for electric vehicles.

This redox flow type battery supplies a battery active material from the outside and performs electrochemical energy conversion in the battery body, and is configured with a unit cell called a liquid flow type electrolytic cell as a minimum unit. Since the electrochemical reaction in the liquid flowing type electrolytic cell is a heterogeneous phase reaction occurring on the electrode surface, it generally involves a two-dimensional electrolytic reaction field. When the electrolytic reaction field is two-dimensional, there is a disadvantage that the reaction amount per unit volume of the electrolytic cell is small. Therefore, in order to increase the reaction amount per unit area, that is, the current density, the electrochemical reaction field has been made three-dimensional.

FIGS. 5A and 5B are schematic diagrams of a liquid flow type electrolytic cell having a three-dimensional electrode.

In the electrolytic cell, an ion exchange membrane 3 is provided between two opposing current collectors 1, 1, and the electrolyte flows along the inner surfaces of the current collectors 1, 1 on both sides of the ion exchange membrane 3. Roads 4a and 4b are formed. A porous electrode material 5 such as a carbon fiber aggregate is provided in at least one of the flow passages 4a and 4b, and thus a three-dimensional electrode is formed.

In the case of a redox flow battery, during discharge, an aqueous chloride solution containing Cr ²⁺ is supplied as an electrolytic solution to the flow passage 4a on the negative electrode side, and an aqueous chloride solution containing Fe ³⁺ is supplied to the flow passage 4b on the positive electrode side. You. Cr ²⁺ emits electrons in the flow passage 4a on the negative electrode side.
Oxidized to Cr ³⁺ . The emitted electrons Fe ³⁺ fed to flow passage 4b is transmitted through an external circuit to the passage 4b of the positive electrode side
To Fe ²⁺ . With this oxidation-reduction reaction, Cl ⁻ becomes insufficient in the flow passage 4a on the negative electrode side, and Cl ⁻ becomes excessive in the flow passage 4b on the positive electrode side. The ion exchange membrane 3 passes Cl ^- through the flow passage 4b on the positive electrode side.
From the flow passage 4a on the negative electrode side. During charging, the reverse reaction proceeds. Porous electrode material 5 in flow passages 4a and 4b
Is provided, the redox reaction is performed in a three-dimensional field, thereby increasing the current density.

(Problems to be Solved by the Invention) In such a liquid flow type electrolytic cell having a three-dimensional electrode made of a porous electrode material, a passage pressure loss due to the electrode material inevitably occurs in the electrode. Since the electrolyte is supplied to the inside of the electrode by the pump, if a liquid passing pressure loss occurs in the electrode, the energy consumption for operating the pump increases, and the total energy efficiency of the battery decreases. If the porous electrode material forming the three-dimensional electrode has the same density, if the thickness of the three-dimensional electrode is increased, it is possible to reduce the liquid passing pressure loss,
The load on the pump can be reduced. However, increasing the thickness of the three-dimensional electrode increases the amount of electrode material used, and raises a new problem of increasing the total cost of the battery.

In the case where discharge is performed intermittently, for example,
Once the electrolytic solution is supplied to the three-dimensional electrode, the supply of liquid is stopped and discharge is performed, and after the discharge reaction of the electrolytic solution in the three-dimensional electrode has progressed to a certain extent, a new electrolytic solution is supplied again and similarly. In the case where discharge is performed and this operation is repeatedly used, in addition to the problem of the pressure loss, the amount of the electrolyte retained in the three-dimensional electrode at the time of stopping the liquid supply becomes a problem. In other words, in order to increase the amount of retained electrolyte in order to lengthen one discharge time,
When the electrode structure has the same density, it is necessary to increase the thickness of the three-dimensional electrode. In this case, similarly to the case of the above-described pressure loss, there is a problem that the total cost of the battery is increased.

The present invention has solved these problems, and it is possible to reduce the pressure loss and increase the electrolyte holding amount in the three-dimensional electrode without increasing the amount of expensive electrode material used. It is an object of the present invention to provide an economical and high-performance liquid-flowing electrolytic cell.

(Means for Solving the Problems) In the liquid flow type electrolytic cell of the present invention, an ion exchange membrane is provided between a pair of current collectors disposed to face each other with a gap therebetween. A liquid circulation type electrolytic cell in which a porous electrode material is provided in a flow path of an electrolytic solution formed between the plate and the ion exchange membrane, wherein the porous electrode material is disposed between the porous electrode material and the ion exchange membrane. In this case, a plate-shaped porous insulating material is provided over the entire surface of the porous electrode plate, thereby achieving the above object.

1 (a) and 1 (b) are an exploded perspective view and a vertical cross section of a liquid flow type electrolytic cell showing one embodiment of the present invention.

The liquid circulation type electrolytic cell includes a pair of current collectors 1 and 1 disposed in parallel at a predetermined interval, and a pair of frame-shaped spacers 2 and 2 disposed between the current collectors 1 and 1. And one ion exchange membrane 3 disposed between the spacers 2 and 2.

The current collector plate 1 is formed of a carbon plate or a conductive synthetic resin plate obtained by kneading a carbon material. The lower and upper portions of the outer surface side of the current collector plate 1 have electrolyte introduction pipes 11 communicating with the inner and outer surfaces, respectively. And an outlet pipe 12 are provided. The spacer 2 is made of an insulating material and is formed in a square frame shape. This spacer 2
Liquid passages 4a and 4b are provided therein, and a porous electrode material 5 and a porous insulating material 6 formed in a plate shape and superposed in the thickness direction are fitted into the liquid passages 4a and 4b. Porous electrode material 5
Are arranged on the current collector 1 side, and the porous insulating material 6 is arranged on the ion exchange membrane 3 side. The total thickness of the porous electrode material 5 and the porous insulating material 6 is set substantially equal to the thickness of the spacer 2 so that no gap is formed between the current collector 1 and the ion exchange membrane 3. Also, both side surfaces of the porous electrode material 5 and the porous insulating material 6 are in close contact with the inner surface of the spacer 2, and the upper and lower ends thereof, that is, the upper and lower ends thereof in the liquid flowing direction are on the inner surface of the spacer 2. It does not adhere, and is between the upper end of the porous electrode material 5 and the porous insulating material 6 and the inner surface of the upper frame of the spacer 2, and the lower end of the porous electrode material 5 and the porous insulating material 6 and below the spacer 2. Gaps 13b and 13a are formed between the inner surface of the frame and the inner surface of the frame. Then, the introduction pipe 11 for the electrolytic solution communicates with the lower gap 13a, and the outlet pipe 12 communicates with the gap 13b.The electrolyte introduced from the introduction pipe 11 into the gap 13a is porous. Electrode material 5
And the outlet pipe 12 through the porous insulating material 6 and through the gap 13b.
Is configured to be derived from the outside. The materials and forms of the porous electrode material 5 and the porous insulating material 6 will be described later.

In the case of a redox flow battery, the electrolytic cell is used as a unit cell. A plurality of such cells are combined into a stack, and a plurality of stacks form a module. The modules are further connected in series to form a string, and the strings are combined in parallel to form a power generation unit. This is a basic combination when a power generation unit is configured by a redox flow battery.

In this electrolytic cell, if the left side of the ion exchange membrane 3 shown in FIG. 1 (b) is a negative electrode and the right side is a positive electrode, a chloride aqueous solution containing Cr ²⁺ as an electrolytic solution is supplied to the current path 4a on the negative electrode side during discharging. Is supplied, and an electrolytic solution composed of a chloride aqueous solution containing Fe ³⁺ is supplied to the liquid passage 4b on the positive electrode side. All electrolytes are stored in independent tanks, and the dedicated pump
Circulated to 4a, 4b.

On the negative electrode side, the electrolytic solution enters the gap 13a of the liquid passage 4a through the introduction pipe 11, and the porous electrode material 5 disposed in the liquid passage 4a.
And the porous insulating material 6 flows upward from below.
At this time, Cr ²⁺ in the electrolytic solution emits electrons and becomes Cr ³⁺ .
The emitted electrons are captured by the porous electrode material 5 and collected on the current collector 1. The electrons collected by the current collector 1 pass through the external circuit toward the positive electrode. Similarly, on the positive electrode side, the electrolyte flows from the bottom to the top through the porous electrode material 5 and the porous insulating material 6. The electrons heading to the positive electrode side reach the porous electrode material 5 via the current collector plate 1 on the positive electrode side, and reduce Fe ³⁺ in the electrolytic solution to Fe ²⁺ via the electrode material 5.

In the electrolytic cell, the cross-sectional area of the liquid passages 4a and 4b in the liquid passage direction is increased by the provision of the porous insulating material 6, thereby decreasing the liquid passage pressure loss. .
If the portion where the porous insulating material 6 is provided is a void, the electrolyte flows intensively in the void, so that the porous electrode material 5 loses its function as an electrode. By arranging the porous insulating material 6 in the portion, it is possible to prevent the electrolytic solution from flowing intensively in the void portion, and the porous insulating material 6 functions as a diffusion tank and passes through the porous insulating material 6. The electrolyte solution to be diffused can also be diffused toward the adjacent porous electrode material 5, and a reduction in electrochemical reaction efficiency such as oxidation-reduction efficiency is prevented. Accordingly, the pressure loss is reduced by the provision of the porous insulating material 6, and the amount of retained electrolyte is increased.

The Cl ⁻ increased on the positive electrode side by the oxidation-reduction reaction in the porous electrode material 5 moves to the negative electrode side on which Cl ⁻ has been reduced through the ion exchange membrane 3. Instead of moving Cl ⁻ , H ⁺ may be moved from the negative electrode side to the positive electrode side. At the time of charging, the reverse reaction proceeds.

Next, the form and material of the porous electrode material 5 and the porous insulating material 6 used in the electrolytic cell of the present invention will be described in detail.

As the porous electrode material used in the electrolytic cell of the present invention,
A carbonaceous fiber aggregate is typical. The carbonaceous fiber aggregate is made of non-woven fabric or spun yarn or filament made from carbonizable raw material fibers, such as coal, pitch obtained from petroleum, phenol novolak, acrylic, aromatic polyamide, or cellulose fibers. Knitted fabric, woven fabric,
It is obtained by processing into a string and then carbonizing.
Alternatively, it can also be obtained by processing into the above structure using carbonized fibers or yarns.

The carbonization treatment is performed according to a conventional method, but the nonwoven fabric, the uneven ground, the woven fabric, or the yarn, the filament bundle is subjected to an anti-oxidation treatment as necessary, and then 500 ° C in an inert atmosphere, preferably 100 ° C.
It is common to heat above 0 ° C.

If the carbonaceous fiber obtained by this carbonization treatment has a graphite microcrystal structure with an average (002) interval (d002) of 3.70 ° or less as determined by X-ray wide angle analysis, When such an aggregate is used as a three-dimensional electrode, the amount of hydrogen generated at the negative electrode during charging is suppressed, and the current efficiency is significantly improved. After the above carbonization treatment, 1 × 10
^{-2 The} number of bound oxygen atoms on the fiber surface determined by ESCA surface analysis when heated in an oxygen atmosphere with an oxygen partial pressure of torr or more and subjected to dry oxidation treatment so that the weight yield is 65 to 99%. Of the number of carbon atoms, that is, the O / C ratio becomes 3% or more. In this case, an oxygen-containing functional group effective for the electrochemical reaction is formed on the surface of the carbonaceous fiber, so that the electrochemical reaction rate is significantly increased and the cell resistance is reduced.

The addition of a boron compound is also effective in suppressing the cell resistance. That is, the non-woven fabric, knitted fabric, woven fabric before the carbonization treatment,
String-like material, yarn, filament bundled yarn, boric acid, boric acid edge, boron oxide, tributyl borate, tripropyl borate, or a boron compound such as triphenyl borate, or non-woven fabric after low-temperature carbonization, The above-mentioned boron compound is impregnated to a knitted fabric, a woven fabric, a string-like material, a yarn, or a bundle of filaments. Thereafter, 0.01 to 50% by weight of boron is contained in the carbonaceous fiber obtained by performing the high-temperature treatment. In this case, an increase in cell resistance due to a change with time when the battery is repeatedly charged and discharged is prevented.

The porous insulating material used in the electrolytic cell of the present invention is, for example, a non-woven fabric, a knitted fabric, a woven fabric, which is processed into a fibrous insulating material, or a molded product of a powdered insulating material, Alternatively, it has a form in which these are combined.
As for the material of the porous insulating material, if it is chemically and electrochemically stable with respect to the electrolytic solution and can be processed into the above-described form,
There is no particular limitation. For example, polyethylene,
Polyolefins such as polypropylene, phenol novolaks, polyamides, organic materials such as polyester, glass fibers, rock fibers, or silica, ceramics such as alumina, but particularly inexpensive polyolefins,
Phenol novolak, glass fiber and rock wool are preferred.

The porosity of the porous insulating material is preferably 60% or more.
When the porosity is less than 60%, the movement of ions in the electrolyte from the porous electrode material to the ion exchange membrane is suppressed, and adverse effects such as an increase in cell resistance and a decrease in the amount of retained electrolyte are caused. Sometimes. In order to promote the diffusion of the electrolytic solution to the porous electrode material side, a density gradient may be provided in the thickness direction of the porous insulating material.

Next, the effectiveness of the porous insulating material in the electrolytic cell of the present invention will be quantitatively described.

The above-mentioned plain woven fabric of the carbonaceous fiber subjected to the dry oxidation treatment is cut into an effective area of 10 cm ² of 10 cm in the weft direction and 1 cm in the warp direction, and is laminated and adjusted to various thicknesses. FIG. 2 shows the results measured by the measurement method described above. Incidentally, the basis weight of the carbonaceous fiber fabric used was 98 / m ^2,
The thickness was 0.37 mm. In addition, a spacer having a thickness of 0.9 times the lamination thickness of the carbonaceous fiber woven fabric was used in the measurement of the liquid passing pressure loss. As shown in FIG. 2, as the thickness of the porous electrode material made of the carbonaceous fiber woven fabric increases, the liquid passing pressure loss decreases, but on the contrary, the amount of the electrode material used greatly increases.

On the other hand, FIG. 3 shows the relationship between the cell resistance and the thickness of the electrode material measured by the above-described measuring method using the liquid pressure loss measuring cell.
From this relationship, it can be seen that the dependence of the cell resistance on the electrode material thickness, that is, on the amount of electrode used per unit electrode geometrical area (basis weight) is much smaller than that of the liquid passing pressure loss. In other words, when the flow rate of the electrolytic solution is the same, it can be said that the contribution to the cell resistance is small even when the thickness of the electrode material is increased by increasing the use amount of the electrode material. However, if the thickness of the electrode material is extremely thin,
If the density is reduced by using an extremely coarse structure, the absolute electrode effective area will be insufficient and the electrode performance will be reduced.Therefore, the basis weight of the electrode material depends on the structure, but is usually 100 g. / m ² or more is required.

FIG. 4 shows the relationship between the thickness of the spacer and the cell resistance when the thickness of the spacer is changed by laminating two carbon fiber plain fabrics. In this case, in order to eliminate the difference in the contact resistance between the electrode material and the current collector, one layer of the carbonaceous fiber plain woven fabric was thermocompression-bonded to the current collector made of conductive plastic, and the measurement was performed. From the results shown in FIG. 4, it can be seen that when the spacer thickness is larger than the electrode material thickness, the liquid passing pressure loss decreases, but the cell resistance sharply increases, and the spacer thickness becomes 1.5 times the electrode material thickness.
It can be seen that when the ratio is twice or more, the measurement becomes almost impossible, and the function as the electrode material is lost.

If the thickness of the spacer is made larger than that of the electrode material, a space is created between the ion exchange membrane and the electrode material, and the loss of liquid passing through this space is much smaller than that of the electrode material. It is understood that the electrolyte solution flows preferentially in this space due to the reduction in size, and the supply of the electrolyte solution to the electrode material portion is not effectively performed.

From the above, as shown in FIG.
By disposing a porous insulating material 6 such as a glass fiber nonwoven fabric between the ion-exchange 3 and the ion-exchange 3, the cross-sectional area of the passage of the electrolytic cell can be increased without increasing the amount of the electrode material 5 used. Thus, the pressure loss caused by passing the electrolytic solution can be reduced. In addition, since the porous insulating material 6 also functions as a diffusion layer for the electrolyte, it is possible to promote the supply of the electrolyte to the porous electrode material 5 and prevent the cell resistance from increasing. Further, since the electrolytic solution is also held in the porous insulating material 6, the discharge time during intermittent discharge can be lengthened. In the present invention, the characteristics are <002> spacing, O / C
Since the evaluation is made based on the ratio, cell current efficiency, cell resistance, liquid passing pressure loss, and intermittent discharge time, the evaluation method will be described in advance.

(A) <002> Spacing The carbonaceous fiber yarn or knitted fabric is powdered in an agate mortar, and 5 to 10% by weight of the sample is mixed with high purity silicon powder for X-ray standard as an internal standard substance. Then, the sample is packed in a sample cell, and a wide-angle X-ray diffraction curve is measured by a transmission diffractometer using CuKα radiation as a radiation source. For the correction of the curve, the following simple method is used without correcting so-called Lorentz, polarization factor, absorption factor, atomic scattering factor and the like. That is, a baseline of the peak corresponding to the <002> diffraction is drawn, and the substantial intensity from the baseline is re-plotted to obtain a <002> corrected intensity curve. Find the midpoint of a line where the line parallel to the angle axis drawn to 2/3 of the peak height of this curve intersects the above corrected intensity curve, correct the angle of the midpoint with the internal standard, Is twice the diffraction angle, and the <002> plane spacing d _{002 is} calculated from the wavelength λ of CuKα and the following Bragg equation.
Ask for.

(However, λ: 1.5418 °, θ: diffraction angle) (b) O / C ratio Measured by X-ray photoelectron spectroscopy, abbreviated as ESCA or XP. Shimadzu ESCA750 was used to measure the O / C ratio.
Analyzed with PAC760. Specifically, each sample was punched out to a diameter of 6 mm, attached to a heated sample stand with a double-sided tape, and provided for analysis. However, before the measurement, the sample was heated to 120 ° C. and evacuated for 3 hours or more. MgKα radiation (1253.6 eV) was used as the radiation source, and the degree of vacuum in the apparatus was set to 10 ⁻⁷ torr. Measure Cl
s, Ols peaks, each peak is ESCAPAC760 (J.
H. Scofield) (based on the correction method), the peaks were obtained and the area obtained was obtained by multiplying the relative intensity of 1.00 for Cls and 2.85 for Ols. Direct surface (oxygen / carbon) atomic ratio%
Is calculated by

(C) Cell Current Efficiency As shown in FIG.
A small flow-type electrolytic cell having an effective electrode area of 10 cm ² in the width direction is made, and charge and discharge are repeated at a constant current density to test the electrode performance. For the positive electrode, a 4N hydrochloric acid aqueous solution having a concentration of ferrous chloride and ferric chloride of 1 M / each was used. The liquid flow rate was set to 4.5 ml per minute and the current density was 4
Set to 0 mA / cm ² , in one cycle test starting from charging and ending with discharging, the amount of electricity Q ₁ required for charging up to 1.2 V
Clone followed by constant current discharge to 0.2V, followed by
And the quantity of electricity taken out at a constant potential discharge at 0.8V and Q ₂ clones respectively, and Q ₃ clones, obtaining the current efficiency by the following equation.

Reactions other than the reduction of Cr ³⁺ to Cr ²⁺ during charging, such as H ⁺
When a side reaction such as reduction occurs, the amount of electricity that can be extracted decreases, and the current efficiency decreases.

(D) Cell resistance The ratio of the quantity of electricity taken out during the discharge to the theoretical quantity of electricity Qth required to completely reduce Cr ³⁺ in the negative electrode solution to Cr ²⁺ is defined as the charge rate, The cell resistance (Ωcm ² ) with respect to the electrode geometric area is obtained from the slope of the current / voltage curve when the charging rate is 50%. The smaller the cell resistance, the quicker the oxidation-reduction reaction of ions at the electrode, the higher the discharge potential at a high current density, the higher the cell voltage efficiency, and the cell is judged to be an excellent electrode. The above cell current efficiency and cell resistance tests were performed at 40 ° C.

(E) Flow pressure loss A mercury manometer was attached to the positive and negative electrolytic solution inlet and outlet flow passages of the electrolytic cell shown in FIG.
The electrolyte is allowed to flow at a rate of 4.5 ml, and the pressure loss through the electrode is calculated by subtracting the blank pressure loss when the electrode is not inserted from the average of the positive and negative electrode pressures.

(F) Intermittent discharge time The electrolytic cell used to measure the cell current efficiency.
Until, after the constant current charge at a current density of 40 mA / cm ^2, to stop the feed solution after electrolysis, was discharged to 0.2V until the current density 20 mA / cm ^2, the time required for discharge at this time It was measured. As the discharge time of the electrolytic solution to the electrode portion is longer, the amount of the electrolytic solution held is larger, and the repeated operation of intermittent discharge can be reduced.

(Operation) The porous insulating material provided between the ion exchange membrane and the porous electrode material functions as follows.

First, the cross-sectional area of the liquid passage can be increased by the amount of the porous insulating material without increasing the amount of the electrode material used. As a result, the pressure loss of the liquid passage is reduced, and the amount of the electrolyte solution is reduced. Retention increases.

Secondly, the porous insulating material forms a passage for the electrolytic solution and at the same time has an appropriate resistance to the flow of the electrolytic solution, so that it functions as an effective diffusion layer for the electrolytic solution.

That is, the electrolytic solution passing through the liquid passage is not concentrated and circulated to the porous insulating material side, but is also effectively diffused and supplied to the porous electrode material side, thereby lowering the oxidation-reduction reaction efficiency. Is prevented.

Third, since the porous insulating material is provided on the ion exchange membrane side and the porous electrode material is provided on the current collector plate side,
The current collection efficiency to the current collector does not decrease.

Fourth, the porous insulating material is very inexpensive as compared with the porous electrode material, and the cost increase due to its use is small.

(Example) Comparative Example A plain woven fabric having a weft density of 47 weft yarns and 45 warp yarns per inch was woven using a twentieth yarn of phenol novolak fiber, which is a 20th spun yarn. This is heated from room temperature to 850 ° C in an inert gas
Up to 1 hour and 30 minutes, hold for 1 hour
The temperature was raised to 2000 ° C. at a temperature rising rate of 600 ° C., and further kept for 30 minutes for carbonization, and after cooling, a carbon fiber plain woven fabric was obtained.

Next, the plain fabric was heated to 700 ° C. in the air, kept for 10 minutes to perform an oxidation treatment, and a basis weight of 168 g / m ² and a thickness of 95 mm.
Of a porous electrode material was obtained. X-ray analysis of porous electrode material <
002> The spacing was 3.62mm, and the O / C ratio by ESCA was 8.1%.

This porous electrode material is 10 cm in the weft direction and 1 cm in the warp direction.
Two test pieces were cut out in the size of, and an electrode test was performed using a spacer having a thickness of 0.45 mm.
82 Ωcm ² , current efficiency 97.5%, liquid pressure drop 338 mmHg, intermittent discharge time 1.4 minutes (16.8 clones).

Example Using a spacer having a thickness of 1.5 mm, between the porous electrode material and the ion exchange membrane, both the positive and negative electrode sides as a porous electrode material, a basis weight of 100 g / m ² , a thickness of 3.5 mm, a porosity of 98.9 % Of glass fiber nonwoven fabric was compressed and interposed, and the same electrode test was performed. The porosity of the glass fiber nonwoven fabric when installed in the spacer was 96.0%. As a result of the measurement,
Cell resistance 1.83Ωcm ² , Current efficiency 97.9%, Fluid pressure loss 27m
mHg, intermittent discharge time was 5.1 minutes (61.2 clones).

That is, in Examples of the present invention, despite the use of a porous electrode material made of the same amount of carbonaceous fiber aggregates as compared with the Comparative Example, the liquid passing pressure loss was significantly lower than 1/10, and The intermittent discharge time with the increase of the electrolyte holding amount was as high as about 3.6 times. The cell resistance was substantially the same.

(Effect of the Invention) According to the present invention, since the porous insulating material is disposed between the porous electrode material and the ion exchange membrane, the liquid passing pressure can be increased without increasing the usage of the electrode material. The loss can be significantly reduced, and the pump driving energy and the like required for liquid passing can be reduced, and the overall energy efficiency can be greatly improved. In addition, since the amount of retained electrolyte can be increased, a single discharge time (discharge capacity) in intermittent discharge can be significantly increased. However, the porous insulating material promotes the diffusion of the electrolytic solution to the porous electrode, and does not cause a reduction in electrochemical reaction efficiency. further,
Since porous insulating material is cheaper than porous electrode material,
Its use only slightly increases the total cost of the battery. Therefore, the electrolytic cell of the present invention can be used for, for example, a redox flow type battery to significantly improve overall energy efficiency and economy.

[Brief description of the drawings]

1 (a) and 1 (b) are an exploded perspective view and a longitudinal sectional view of a liquid flow type electrolytic cell showing one embodiment of the present invention, and FIG. FIG. 3 is a graph showing the relationship between the thickness of the porous electrode material and the cell resistance, FIG. 4 is a graph showing the relationship between the thickness of the spacer, the cell resistance and the pressure loss through the liquid, and FIG. Fig. 5 (a)
(B) is a schematic diagram showing a basic structure of a liquid flowing electrolytic cell. 1 ... current collecting plate, 3 ... ion exchange membrane, 4a, 4b ... liquid passage, 5 ... porous electrode material, 6 ... porous insulating material.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H01M 8/00-8/02 H01M 8/08-8/24

Claims (1)

(57) [Claims] An ion exchange membrane is disposed between a pair of current collectors disposed opposite each other with a gap therebetween, and an electrolyte formed between the current collector and the ion exchange membrane is formed. A liquid-flowing electrolytic cell in which a porous electrode material is provided in a liquid passage, wherein a plate-shaped porous insulating material is provided between the porous electrode material and the ion exchange membrane on the porous electrode plate. A liquid flow type electrolytic cell, which is disposed over the entire surface of the electrolytic cell.