FI118344B - Cell structure and method of assembly - Google Patents

Description

1, 118344

CELL STRUCTURE AND METHOD FOR ASSEMBLY IT

ENGINEERING

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The present invention relates to a cellular structure having an electrolyte polymeric film, electrode plates placed on the active surfaces of the polymeric film, and channel plates having channels and ridges, and a method for making such a cellular structure.

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TECHNICAL BACKGROUND

Electrolysis is the process of either converting the energy released in a chemical reaction into an electric current or performing a chemical reaction using the energy of an electric current. 15 An electrolytic cell is a device in which electrolysis is performed. It consists essentially of a vessel filled with an electrolyte and two electrodes immersed in an electrolyte. An electrolyte is a solution which is partially dissociated into ions and thus conductive. Water is one of the electrolyte materials. Some polymers may also act as electrolytes.

20: [[[: The electrode is a conductive material that contacts the electrolyte so that charge can be transferred between it and the electrolyte ions. The electrolytic cell is connected to an external circuit via electrodes. Electrodes are called anodes and cathodes,

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one of which is negative and the other positive depending on whether the cell is used • ·:. i 25 for the production of chemicals or electricity. In the latter case, the cell • «« is called the pickup cell. The electrodes and the medium thus form a circuit when the electrodes are connected to each other.

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* ”· 'Thus electrolysis is used e.g. chemical processes for the production of gases and chemicals. The electrolyte required may be either a liquid bath or a solid polymer, so called. PEM

ΦΙ »membrane (PEM - Polymer Electrolyte Membrane or Proton Exchange Membrane). PEM -: * ·. · Membrane is used, for example, to produce hydrogen and oxygen (in water electrolysis) and to generate electricity and heat by fuel cells. Hydrogen produced by water electrolysis is used either as a fuel in the field or as a gas for energy storage.

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The surfaces of the electrolyte are made active on both the anode and cathode sides by a catalyst coating, most commonly platinum or alloys thereof. The electrolysis feedstock, water or gas, is conducted to the anode or the cathode (and the electrolysis product out there). The raw material is then transported to the active electrolyte through a channel plate 5 through a diffusion plate which serves to support, moisten and conduct electricity to the electrolyte film. Thus, in addition to the material carrying capacity, the duct and diffusion plate are required to have the highest possible electrical conductivity so that the electrical current through the entire cell structure has the smallest electrical resistance to overcome. It is also required for good corrosion resistance, since the conditions in the 10 cells are highly corrosive. An additional requirement is good thermal conductivity, since the heat generated by electrolysis must be removed from the cell.

The material transfer plates, i.e. the channel plate (also called bipolar plate) and the diffusion plate, are made of an electrically conductive material. The channel plate is engraved grooves 15, along which the material moves into and out of elektrolyytillle, while the grooves of the ridges are formed through a metal net or carbon paper diffusion plate, in contact with the anode side or the cathode side surface. A diffusion plate is required to support the flexible and mechanically weak electrolyte film so that it does not bend into the grooves and is not damaged. The electrolyzable substance must be able to pass freely through the diffusion plate and be made of a metal or carbonaceous material to provide electrical conductivity.

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Prior art cell structures have encountered difficulties in assembling it, for example in sealing, and in the construction of an electrolyte / electrode • · 25 connection, which was not sufficiently developed. Poor surface connections lead to a decrease in the power of the cell 4 4 «.

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Dimensionally manufacturing the electrode plates to tight tolerances will improve the problem, but it is expensive to obtain sufficient sealing. For high power cells, the improved 30 dimensional accuracy provides a significant cost advantage, which complicates the commercialization of polymeric electrolyte cells (though generally not accurate enough). However, practice has shown that even with larger electrode surfaces, even small deviations in dimensional accuracy lead to poor surface connections.

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The invention relates to a cell structure having a sufficiently good contact between the electrolyte and the electrodes.

BRIEF DESCRIPTION OF THE INVENTION

The cellular structure according to the invention comprises an electrolyte polymer film, electrode plates placed on the active surfaces of the polymer film, and channel plates with channels and ridges. The invention is mainly characterized in that, in the assembled structure 10, the brush points between the channels of the second plate contact the channels of the second plate to improve the connection between the electrolyte film and the electrode plates. The cell structure is compressed up to the gaskets so that the structure thanks to the fact that the brush points are 15 mm narrower than the channel points.

The cellular structure is thus compressed so tightly that no gaps remain in the structure at the seals.

In the method of the invention, the components of the honeycomb structure are assembled such that in the assembled structure, the bristle between the channels of the second channel plate aligns with the channels of the other channel to improve the connection between the electrolyte film and electrode plates. is ··· sealed at the seals and has a flexible point at the duct brushes • · 25.

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In prior art solutions, the channels in the channel plates are made · · symmetrical, so that when they are aligned, the ends of the plates are • · **: ** opposite. This structure is not flexible.

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BRIEF DESCRIPTION OF THE DRAWINGS

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Figure 1 shows, by way of example, a general view of a unit cell structure in which the individual components 35 are distinguished.

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Fig. 2 shows an assembled honeycomb structure according to the invention.

Figure 3 shows, for comparison, a prior art honeycomb assembly.

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DETAILED DESCRIPTION

Devices having 10 polymer films as electrolyte have been commercially available for several years. In both the embodiment of Figure 1 and Figure 2, a solid polymeric film is used as the electrolyte membrane of the honeycomb structure. A suitable polymer film is manufactured, for example, by DuPont under the trade name Nation. Figure 1 illustrates the unit cell solution shown in F1 patent application 20011044 developed by the applicant.

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The electrolyte cell 1 shown in Figure 1 is for electrolysis of water. The cell is shown with components separately for illustrative purposes. The electrolyte is a polymer film 2 whose surfaces are made active by coating the film on both sides with a suitable noble metal alloy. For example, 20 platinum metals and their alloys are used as precious metal alloys. On the active surfaces, electrically conductive • · · diffusion / electrode plates (3,4), of which the anode diffusion plate is designated by reference numeral 3 and • ·:. *, The cathode diffusion plate (3, 4) are • ♦ · connected to an external electrical voltage source 13, 14. Electrode / diffusion plates (3, 4) • ··: · * ·: consist of areas outside the cell, so-called. switching areas 11 and 12, gas and / or • · · 25 fluid-permeable diffusion zones 5 and 6, and diffusion space boundary sealing surfaces 15 and 16. Electrode / diffusion plates 3,4 are made of a conductive material.

In the embodiment of the invention according to Fig. 1, electrolysis 30 is carried out in the process of producing hydrogen gas. The water is led to the cell 1 through the inlet 9 through the channels 7 in the channel plate 8. From the channels 7 of the channel plate, water passes through the holes in the diffusion region 5 of the diffusion plate 3 to the surface of the polymer film 2. Thereafter, the switching regions 11 and 12 of the electrode / diffusion plates 3 and 4 are coupled to an electrical voltage source 13, 14, whereby an electric potential is formed across the electrolyte. After 35 water molecule comes into contact on the active anode side (the input side) with surface 5 118 344, it disperses the oxygen and hydrogen ions, O 2 'and H *. Each of the oxygen-ion electrolyte to the anode side surface of the transferred electrons and two oxygen atoms agrees with the oxygen molecule 02, which is led out of the cell via diffusion through channels in the channel plates 3 to the output 19. The hydrogen ion migrates prototype Nina membrane 2 through the cathode 4, 5 where it receives an electron. The two hydrogen atoms on the cathode form the hydrogen molecule H2, which is passed through the diffusion plate 4 through the channels (not shown) in the channel plate 10 and the outlet 17 out of the cell. The function of the channel plate 10 is to support both the electrode and to act as a space into which hydrogen is introduced. In some embodiments, the seals 20 are integrated with the channel plates or in the same structure as the electrodes.

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In order to pressurize and recover the hydrogen produced, the cell must be made as gas-tight as possible. Seals 20 prevent gas or water leakage. The sealing must be done very carefully, since small molecules of hydrogen penetrate even the smallest leakage points, rendering the cell unusable or, in any case, creating 15 security risks. The more parts the cell body consists of, the more gaskets and a precisely machined sealing surface are required.

Heat is supplied to the outside of the cell via electrode / diffusion plates 3 and 4.

In the solution of Figure 1, the cell is used to produce gas. When using a fuel cell for energy production, hydrogen gas is conducted to the anode (+), where it decomposes into atoms and releases electrons.

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Anode Reaction: \ * ·: 25 · * ·: 2 H2 - 4 e '-> 4 H + • · ♦ 9

Protons (H *) pass through an electrolytic membrane to the cathode. Electrons pass through an external · · '*: ** circuit from the cathode to the anode.

30 Cathode Reaction: * ·· • · 9 9,999 9

Oxygen is supplied to the cathode where it is combined with hydrogen into water.

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The cellular structure of the invention shown in Figure 2 can be used either in the unit cell solution of Figure 1 or in another unit cell having duct plates. The entire honeycomb assembly is assembled from successive unit cells and pressed between the end-plates by means of surface bolts. The contacts between the polymer electrolyte and the electrodes 5 must be made as good as possible, since even a small distance between them causes the electric current to pass through them.

In the solution of Figure 2, duct plates (8, 10) are mounted behind the electrode plates (3,4) so that the brush points (25) 10 between the channels of the first plate (8) are aligned with the channels (7 ') of the second plate (10) respectively, the ridges (25 ') of the second plate (10) coincide with the channels (7) of the first plate (8). Since the electrode plates 3 and 4 and the electrolyte film 2 are flexible, a flexible point is formed in the structure at the channel ridges 25, 25 '. As a result, the entire structure is resilient so that the cell can be pressed down to the seals 20 so that the seal 15 is secured while the connection between the electrolyte film and the electrode plates is maximized over the entire surface area.

In the prior art solution of Fig. 3, the duct plates (8, 10) are mounted such that the ridges (25) between the channels of the first plate (8) coincide with the ridges (25 ') of the second plate 20 (10) 7 ') at the channels (7) of the first plate (8).

9 In this case, the structure will not be resilient and the contact between the electrolyte and the electrodes ♦ ·· may not occur at times due to differences in plate thickness.

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The above-described embodiments of Figures 1 and 2 according to the invention are not intended to limit the invention, but the details may vary within the scope of the invention and the skill of the person skilled in the art. edges can be rounded to 30 etc.

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Claims (2)

A cell structure (1), wherein a polymer membrane (2) acts as an electrolyte, electrode discs (3,4) placed on top of the active surfaces of polymeric membranes 5 (2) and channel discs (8, 10) with channels (7, 7 '). ) and axes (25, 25 '), characterized in that in the assembled construction, the axes (25, 25') between the channels (7, 7 ') of one channel disk (8, 10) are opposite the channels of the other disk. to improve the connection between the electrolyte membranes (2) and the electrode discs (3, 4), which cell structure is pressed all the way up to the seals (20) in such a manner that the structure is without openings at the seals and that a flexible position has been established at the channel readers ( 25, 25 ') due to the size of the ridge sites (25, 25') being narrower than the channel sites (7, 7 '). A method of assembling a cell structure (1), wherein a polymer membrane (2) acts as an electrolyte, electrode discs (3, 4) placed on top of the active surfaces of the polymeric membranes (2), and channel discs (8, 10) with channels (7, 7 ') and axes (25, 25'), characterized in that said components are assembled such that in the assembled structure the yoke site (25, 25 ') will hit the location of the channels (7, 7') by one channel plate (8, 10) for improving the connection 20 between the electrolyte membranes (2) and the electrode discs (3, 4), and which cell structure is pressed all the way to the seals (20) in such a way that the structure is without openings at the seals and that a flexible position is raised by the channel readers (25, 25 '). «· • • · ··· · · · · · · · · · · · · · · · · ♦ ·· ·« • M ··· • t • · • m · • · * ·· • · • M · 1 · · · · · · · · · · · · ·