KR102662952B1 - Alkaline electrolysis stack assembly - Google Patents

Abstract

The present invention includes a unit stack in which a bipolar plate, a diffuser, and an electrode are sequentially arranged on the cathode side and the anode side with respect to the separator to be symmetrical to each other, and a plurality of the unit stacks are modularized by stacking them in a filter press method. This relates to an alkaline water electrolysis stack assembly, which can simplify gas and liquid flow paths, secure performance by reducing internal resistance, and flexibly respond to various capacities.

Description

Alkaline electrolysis stack assembly

The present invention relates to an alkaline water electrolysis stack assembly combining the single cell stacking method and the filter press stacking method.

Among hydrogen production technologies, water electrolysis is a technology that electrolyzes water to produce high purity (99.999%) green hydrogen, including alkaline water electrolysis (AEL) and polymer electrolyte membrane electrolysis (PEMEL). , Solid Oxide Electrolyser Cell (SOEC) technology, etc.

Among these, alkaline water electrolysis is a technology that generates hydrogen and oxygen by electrolyzing water in a basic environment using an aqueous alkaline solution such as KOH or NaOH as an electrolyte. It has been studied for the longest time and is stable and price competitive through various technologies. This has been proven and the technological maturity is high. Specifically, polymer electrolyte membrane water electrolysis (PEM) uses a precious metal catalyst, but alkaline water electrolysis uses nickel or stainless steel as the main material rather than an expensive precious metal catalyst, so the initial installation cost is relatively low and the system lifespan is relatively low. This technology is suitable for long and large-capacity hydrogen generation.

The water electrolyzer stack used in this alkaline water electrolysis technology consists of hydrogen and oxygen generating electrodes, a separator, a gasket, and a current collector plate. And, the stack of conventional alkaline water electrolysis technology can be divided into a single cell stacking method that stacks single cells and a filter-press method that is a modification of chloro-alkaline technology. Here, the stacking method of stacking a single cell consists of sequentially connecting the cell frame connecting the end plate, current collector, gasket, mesh-type diffusion layer, electrode, and separator to form a single cell, and stacking the desired number of cells with bolts. Fix it to form a stack. In addition, the filter press method modifies the conventional chloro-alkali process to form a stack by connecting a desired number of single cells. These conventional stacking methods can secure capacity by stacking the required number of single cells, simplify the gas and liquid flow paths by continuously connecting single cells, and reduce internal resistance, which is advantageous for securing performance. do.

However, among conventional water electrolysis technologies, single-cell stacking has the disadvantage that when components are damaged or performance deteriorates, the entire stack must be separated and the components must be replaced, so the operation of the water electrolysis system is forced to stop for a long period of time and on-site measures are difficult. There is. In addition, in the single-cell stacking method, when dozens to hundreds of single cells are stacked, it is difficult to accurately align and arrange the components without steps between the stack components.

In addition, the filter press stack is a type that modifies the method of producing caustic soda (NaOH) in the conventional chloro-alkali technology, and the volume of a single cell is large, and compared to the stack method, the volume is larger for hydrogen production of the same capacity. occupies Moreover, since the filter press stack is manufactured through internal welding between parts when manufacturing a single cell, it is difficult to replace when the product is damaged or its performance deteriorates. In addition, the filter press stack requires a larger number of parts compared to the stack method because the flow path or gas flow is configured individually when stacked on top of each other in a single cell structure, and management difficulties arise.

Prior Art Document 1: Public Patent Publication No. 10-2021-0010231 (2021.01.27.)

Prior Art Document 2: Publication of Patent No. 10-2003-0090653 (2003.11.28.)

The present invention was invented to solve the above-mentioned problems. By combining the single cell stacking method and the filter press method, a plurality of independent stacks are connected sequentially by the filter press method, thereby simplifying the flow path of gas and liquid, The purpose is to provide an alkaline water electrolysis stack assembly that can secure performance by reducing internal resistance and can flexibly respond to various capacities.

Meanwhile, the technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and anyone with ordinary knowledge in the technical field to which the present invention pertains can clearly understand other technical problems not mentioned above. There will be.

In order to achieve the above-described object, the present invention includes a unit stack in which a bipolar plate, a diffuser, and an electrode are sequentially disposed on the cathode side and the anode side with respect to the separator to be symmetrical to each other, and a plurality of the unit stacks It is characterized by being modularized by stacking using the filter press method.

Preferably, the unit stack includes a pair of cell frame supports, and between the pair of cell frame supports is the bipolar plate, diffuser, and electrode on the cathode side and the bipolar plate, diffuser, and electrode on the anode side. It is characterized by being stacked in a zero-gap manner.

Preferably, a thin film bipolar plate is inserted between the bipolar plate and the diffuser, the diffuser is laminated on the back of the thin film bipolar plate, and the diffuser is a porous material manufactured by a mesh, knit, or foam method, The diffuser is characterized by having pores of 10㎛ ~ 10mm and a thickness of 0.1mm ~ 20mm.

Additionally, the electrode is laminated on the back of the diffuser, the separator is laminated between a pair of electrodes, and a gasket is installed to prevent water leakage between the bipolar plate, the thin film bipolar plate, and the diffuser. It is characterized by

Preferably, the cell frame support is characterized by having separate cathode chambers and anode chambers.

The present invention further includes a pair of module frames accommodating the plurality of unit stacks and a filter press pressing mechanism for modularizing the plurality of unit stacks by pressurizing and stacking them in a filter press method, wherein the filter press pressing mechanism includes the above one. a hydraulic piston that presses one module frame of the pair of module frames against the side of the other module frame; and an adjustment screw disposed at a corner of one of the pair of module frames to individually adjust the gap and pressure between the module frame and the unit stack.

Preferably, it further includes a hydrogen discharge manifold, an oxygen discharge manifold, a hydrogen electrolyte inlet manifold, and an oxygen electrolyte inlet manifold disposed along the longitudinal direction of the modularized unit stacks, the hydrogen discharge manifold comprising: The oxygen discharge manifold, the hydrogen electrolyte inlet manifold, and the oxygen electrolyte inlet manifold are arranged independently of each other and connected to the unit stacks.

Preferably, the bipolar plate has a contact surface having at least one elastic structure, and the elastic structure includes a metal plate bent and extended from the contact surface of the bipolar plate and disposed in parallel with the contact surface at a predetermined distance. It is characterized by:

More preferably, the elastic structure includes: a spring installed between the contact surface of the bipolar plate and the metal plate to elastically restore the metal plate; and a spring fixture extending from the contact surface of the bipolar plate toward the metal plate and having the spring installed on the outer periphery to limit the amount of compression of the spring.

According to the present invention, one unit stack is composed of 1 to 100 or more electrodes and a separator connected, and 1 to 200 or more unit stacks are continuously connected using a filter press to form one water electrolysis stack assembly. You can. Accordingly, it is possible to manufacture water electrolysis stack assemblies of various capacities that satisfy the desired power generation capacity. Accordingly, water electrolysis stack assemblies of various capacities that satisfy the desired power generation capacity can be freely adjusted and configured, thereby reducing the size of the device and reducing manufacturing costs.

In addition, according to the present invention, when each unit stack fails or performance deteriorates, the pressure of the filter press pressurizing mechanism can be easily released and only the corresponding unit stack can be separated and easily repaired or replaced.

In addition, according to the present invention, the manifolds for transporting electrolyte, hydrogen, and oxygen have a continuous flow path structure independently of each other, and by applying a continuous bipolar current application method, the volume and power consumption of the device can be reduced. there is.

1 is an exploded perspective view showing a unit stack of an alkaline water electrolysis stack assembly according to the present invention;
Figure 2 is a perspective view showing an alkaline water electrolysis stack assembly according to the present invention in which the unit stacks of Figure 1 are stacked by a filter press method;
Figure 3 is a perspective view showing a bipolar plate of an alkaline water electrolysis stack assembly according to the present invention;
Figure 4 is a side view showing the bipolar plate of Figure 3;
Figure 5 is a plan view showing the cell frame support of the alkaline water electrolysis stack assembly according to the present invention.

Hereinafter, a preferred embodiment of an alkaline water electrolysis stack assembly according to the present invention will be described with reference to the attached drawings. For reference, in describing the present invention below, terms referring to the components of the present invention are named in consideration of the function of each component, and should not be understood as limiting the technical components of the present invention. It will be.

Referring to Figures 1 and 2, the alkaline water electrolysis stack assembly 10 according to the present invention is composed of a plurality of unit stacks 100, and each unit stack 100 has a cathode based on the separator 110. ) side and the anode side, respectively, the bipolar plate 120, the diffuser 130, and the electrode 140 are sequentially arranged to be symmetrical to each other. Then, the plurality of unit stacks 100 are modularized by stacking them using a filter press method.

Specifically, the unit stack 100 includes a pair of cell frame supports 150, and within the cell frame supports 150, a bipolar plate 120 on the cathode side, a diffuser 130, an electrode 140, and The bipolar plate 120, the diffuser 130, and the electrode 140 on the anode side are symmetrically stacked. Here, the bipolar plate 120 is a metal plate that functions as a busbar for applying external current to the electrode 140, and serves to connect current between each unit stack 100 in the filter press method. Additionally, the diffuser 130 serves to evenly diffuse the fluid supplied from the separator 110 to the anode-side electrode 140 and the cathode-side electrode 140.

A thin film bipolar plate 160 may be inserted between the bipolar plate 120 and the diffuser 130. This thin film bipolar plate 160 serves to connect the current applied to the bipolar plate 120 to the internal electrode 140, and can be manufactured using SUS, nickel plating, nickel plate, coating, and plasma. Additionally, a diffuser 130 is stacked on the back of the thin film bipolar plate 160. This diffuser 130 is a porous body manufactured using a mesh, knit, or foam method, and may have, for example, pores of 10 μm to 10 mm and a thickness of 0.1 mm to 20 mm.

Meanwhile, the electrode 140 is stacked on the back of the diffuser 130, and the separator 110 is stacked between the pair of electrodes 140. Here, the electrode 140 can mainly be made of transition metals such as Ni, Fe, Co, Mo, etc. based on nickel, iron, etc., and mixed oxides mixed with these transition metals can be used as porous bodies (perforated plates, meshes, etc.) of various metals. Expanded metal, knit) can be manufactured by coating, plasma, or plating processing. In addition, the separator 110 stacked between the electrodes 140 may be a porous composite in which ceramic particles are dispersed to ensure durability in a strong base environment. For example, a zirconium mixture may be sprayed on a PPS or PPSU polymer matrix support. It can be manufactured by: Additionally, a gasket 170 may be installed between the bipolar plate 120, the thin film bipolar plate 160, and the diffuser 130 to prevent water leakage.

Meanwhile, the cell frame support 150 can be made of a material that is resistant to strong alkalis, such as PS, PESU, PP, PPSU, SUS, and PTFE, and is composed of a pair to provide a flow path for discharging hydrogen and oxygen and an inflow of electrolyte. and a flow path for discharge. This pair of cell frame supports 150 are stacked symmetrically with respect to the separator 110, and have the above-described bipolar plate 120, diffuser 130, electrode 140, separator 110, and gasket inside. It plays a role in connecting (170). In particular, the bipolar plate 120, diffuser 130, electrode 140, separator 110, and gasket 170 stacked inside the pair of cell frame supports 150 have a zero-gap. It is stacked in a way that makes current connection smooth and has the effect of reducing current loss with low resistance.

Preferably, the alkaline water electrolysis stack assembly according to the present invention is formed by pressurizing and stacking a pair of module frames 200 accommodating a plurality of unit stacks 100 and a plurality of unit stacks 100 using a filter press method. It includes a filter press pressurizing mechanism 300 that is modularized.

A pair of module frames 200 includes internal parts to make the unit stacks 100 into a single cell structure, namely, a bipolar plate 120, a diffuser 130, an electrode 140, a separator 110, It serves as an external case to accommodate the gasket 170. This module frame 200 may be made of a material that is corrosion resistant to strong alkalis, such as PS, PESU, PP, PPSU, SUS, or PTFE, and has a structure that consists of a pair and is fastened using bolts and nuts.

The filter press pressing mechanism 300 includes a hydraulic piston 310 and adjustment screws 320. The hydraulic piston 310 serves to pressurize one module frame (e.g., anode side module frame) of a pair of module frames 200 toward the other module frame (e.g., cathode side module frame). do. In addition, the adjustment screw 320 is disposed at each corner of one of the pair of module frames 300 (for example, the anode side module frame) to adjust the gap and pressure between the module frame 300 and the unit stack 100. It plays a role in individually controlling the

Here, the hydraulic piston 310 serves to adjust the pressure between the unit stacks 100 and the parts inside the unit stacks 100, and the adjustment screws 320 maintain the flatness of the unit stacks 100. By adjusting the surface, detailed pressure control between unit stacks 100 is possible.

In particular, according to the present invention, one unit stack 100 is formed with a structure in which 1 to 100 electrodes and a separator are connected, and 1 to 200 unit stacks 100 are continuously connected using a filter press method. One water electrolysis stack assembly 10 can be constructed. Accordingly, water electrolysis stack assemblies of various capacities that satisfy the desired power generation capacity can be freely adjusted and configured. In addition, when each unit stack 100 breaks down or performance deteriorates, the pressure of the filter press pressurizing mechanism can be easily released and only the corresponding unit stack 100 can be separated and repaired or replaced.

Preferably, along the longitudinal direction of the modularized unit stacks 100, that is, along the longitudinal direction of the water electrolysis stack assembly 10, a hydrogen discharge manifold 20, an oxygen discharge manifold 30, and a hydrogen electrolyte are formed. The inlet manifold 40 and the oxygen electrolyte inlet manifold 50 may be arranged independently of each other. For example, based on FIG. 2, the hydrogen discharge manifold 20 is disposed on the upper left side of the water electrolysis stack assembly 10, and the oxygen discharge manifold 30 is located on the upper right side of the water electrolysis stack assembly 10. is disposed, the hydrogen electrolyte inlet manifold 40 is disposed at the lower right of the water electrolysis stack assembly 10, and the oxygen electrolyte inlet manifold 50 is disposed at the lower left of the water electrolysis stack assembly 10. It can be. And, these manifolds 20, 30, 40, and 50 are arranged independently from each other and individually connected to the unit stacks 100. Through the arrangement and connection structure of these manifolds 20, 30, 40, and 50, the volume and power consumption of the product can be reduced, and damage to the equipment due to shunt current can be prevented.

Meanwhile, in the case of a filter press type water electrolysis stack, when current is applied to each unit stack in a monopolar manner, the sum of the applied currents generates a much higher voltage than in the bipolar type. For this reason, the present invention adopts a bipolar stacking method. Of course, when multiple unit stacks 100 are used, monopolar current application is also possible.

In addition, in the filter press method, when each unit stack 100 is stacked, the flatness imbalance of the contact surfaces results in a high resistance value, which generates heat and deteriorates product performance. The present invention has a structure to minimize unevenness in the flatness of component contact surfaces during stacking.

Specifically, referring to FIGS. 3 and 4, the bipolar plate 120 of the alkaline water electrolysis stack assembly according to the present invention has a contact surface 121 having at least one elastic structure 180. This elastic structure 180 may include a metal plate 181 bent and extended from the contact surface 121 of the bipolar plate 120. Additionally, this metal plate 181 is arranged in parallel with the contact surface 121 of the bipolar plate 120 at a predetermined distance apart.

Since the metal plate 181 of the elastic structure 180 of the bipolar plate 120 has a certain elasticity in the form of a leaf spring, the bipolar plate 120 and the electrode 140 of the unit stack 100 are sufficient. Since it can be connected by area and force, internal resistance can be reduced.

Preferably, the elastic structure 180 of the bipolar plate 120 further includes a spring 182 and a spring fixture 183 to restore the elasticity of the metal plate 181 and limit the amount of elastic deformation of the metal plate 181. It can be included.

Specifically, the spring 182 is installed between the contact surface 121 of the bipolar plate 120 and the metal plate 181 and serves to elastically restore the metal plate 181. This spring 182 may be an elastic member of various types, such as a leaf spring, tension spring, or compression spring. In addition, the spring fixture 183 extends from the contact surface 121 of the bipolar plate 120 toward the metal plate 181, and a spring 182 is installed on the outer periphery to limit the amount of compression of the spring 182, It serves to limit the amount of elastic deformation of the metal plate 181.

For example, the metal plate 181 of the elastic structure 180 may repeat compression and restoration within a set value of 1 to 5 mm by the spring 182 and the spring fixture 183. In addition, the springs 182 may be composed of 5 to 50 springs 182 depending on the size of the unit stack 100, and the compression range of the metal plate 181 can be set by changing the installation position of the spring 182.

Referring to FIG. 5, the cell frame support 150 of the unit stack 100, which serves to induce the flow of internal electrolyte or gas, has a separate cathode chamber 151 and an anode chamber 152 to supply electrolysis. As a result, damage to the product or deterioration in performance due to shunt current can be prevented.

The embodiments of the present invention described above merely exemplify the technical idea of the present invention, and the scope of protection of the present invention should be interpreted in accordance with the scope of the patent claims below. In addition, those skilled in the art to which the present invention pertains will be able to make various modifications and variations without departing from the essential characteristics of the present invention, and all technical ideas within the scope equivalent to the present invention shall be construed as the scope of the present invention. It should be interpreted as being included in the scope of rights.

10: Stack assembly 20: Hydrogen discharge manifold
30: Oxygen discharge manifold 40: Hydrogen electrolyte inlet manifold
50: Oxygen electrolyte inlet manifold 100: Unit stack
110: Separator 120: Bipolar plate
130: diffuser 140: electrode
150: Cell frame support 160: Thin film bipolar plate
170: gasket 180: elastic structure
181: elastic plate 182: spring
183: spring fixture 200: module frame
300: Filter press pressurizing mechanism 310: Hydraulic piston
320: adjustment screw

Claims (9)

An alkaline water electrolyzer comprising a unit stack in which a bipolar plate, a diffuser, and an electrode are sequentially arranged on the cathode side and the anode side with respect to the separator to be symmetrical to each other, and modularized by stacking a plurality of the unit stacks using a filter press method. As a stack assembly,
The bipolar plate has a contact surface having at least one elastic structure, and the elastic structure includes,
a metal plate bent and extended from the contact surface of the bipolar plate and disposed in parallel with the contact surface at a predetermined distance;
a spring installed between the contact surface of the bipolar plate and the metal plate to elastically restore the metal plate; and
An alkaline water electrolysis stack assembly, comprising a spring fixture extending from the contact surface of the bipolar plate toward the metal plate and having the spring installed on an outer circumference to limit the amount of compression of the spring.
According to paragraph 1,
The unit stack includes a pair of cell frame supports, and between the pair of cell frame supports, the bipolar plate, diffuser, and electrode on the cathode side and the bipolar plate, diffuser, and electrode on the anode side have a zero-gap. An alkaline water electrolysis stack assembly, characterized in that it is stacked in a stacked manner.
According to paragraph 2,
A thin film bipolar plate is inserted between the bipolar plate and the diffuser, the diffuser is laminated on the back of the thin film bipolar plate, the diffuser is a porous material, and the diffuser has pores of 10 μm to 10 mm and 0.1 mm to 0.1 mm. An alkaline water electrolysis stack assembly, characterized in that it has a thickness of 20 mm.
According to paragraph 3,
The electrode is laminated on the back of the diffuser, the separator is laminated between a pair of electrodes, and a gasket is installed to prevent water leakage between the bipolar plate, the thin film bipolar plate, and the diffuser. Alkaline water electrolysis stack assembly.
According to paragraph 2,
The cell frame support is an alkaline water electrolysis stack assembly, characterized in that the cathode chamber and the anode chamber are separately constructed.
According to paragraph 1,
It further includes a pair of module frames accommodating the plurality of unit stacks and a filter press pressing mechanism for modularizing the plurality of unit stacks by pressing and stacking them in a filter press method,
The filter press pressurizing mechanism is,
a hydraulic piston that presses one module frame of the pair of module frames toward the other module frame; and
An alkaline water electrolysis stack assembly, characterized in that it includes an adjustment screw disposed at a corner of one of the pair of module frames to individually adjust the gap and pressure between the module frame and the unit stack.
According to clause 6,
It further includes a hydrogen discharge manifold, an oxygen discharge manifold, a hydrogen electrolyte inlet manifold, and an oxygen electrolyte inlet manifold disposed along the longitudinal direction of the modularized unit stacks,
An alkaline water electrolysis stack assembly, wherein the hydrogen discharge manifold, oxygen discharge manifold, hydrogen electrolyte inlet manifold, and oxygen electrolyte inlet manifold are arranged independently of each other and connected to the unit stacks.
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