RU2496186C1 - Fuel element and battery of fuel elements - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: fuel element (1) includes membrane-electrode assembly (2), to which anode adjacent is elastic plated dielectric gasket from inert material (12), also the first and the second gasket seals (5), (8). In the central part of elastic plated dielectric gasket (12) there made is a hole for passing of anode gas (hydrogen) to membrane-electrode assembly (2). To elastic plated dielectric gasket (12) adjacent is a plate (14) with gas-distributing channels (15) and branch tubes 16, 17 for input and output of anode gas. Battery of fuel elements includes at least two membrane-electrode assemblies (2).

EFFECT: increasing efficiency of energy conversion due to reduction of losses per electric resistance, increasing stability of electrical resistance in time.

6 cl, 9 dwg

Description

The invention relates to the field of electrochemical energy, and in particular to devices for the direct conversion of chemical energy of hydrogen-containing fuel into electrical energy.

One of the strengths of electrochemical energy converters, which include fuel cells (FCs), is their high energy efficiency. Due to direct energy conversion, they have a high efficiency, which theoretically can reach 100%, however, the efficiency of energy conversion in fuel cells depends on many factors, and to a large extent depends on the optimal design of the product. A very significant factor determining the overall efficiency of the device is the heat loss during current collection from the electrodes. Reducing the energy losses associated with the design of fuel cells is currently an urgent task.

A fuel cell is known (see application EP 2417663, IPC H01M 8/02, H01M 8/24, published 02/15/2012), including a furniture-electrode block containing a proton-conducting membrane, to which are adjacent an anode gas diffusion layer and a cathode gas diffusion layer. Anode and cathode separate plates are adjacent to the anode gas diffusion layer and the cathode gas diffusion layer, respectively. An elastic sealing gasket is located on the periphery of the membrane-electrode block.

This design of the known TE makes it possible to stabilize its operation, which limits the scope of the known TE. In addition, this design does not provide a stable low electrical resistance during operation of the fuel cell.

A known fuel cell battery (see patent RU 2387053, IPC H01M 8/10, H01M 8/24, published on April 20, 2010) includes two FCs, each of which includes an anode electrode with an anode gas diffusion layer, a cathode electrode with a cathode gas diffusion layer, and proton conducting membrane located between the cathode and anode diffusion layers. FCs face each other with anode electrodes, between which a dielectric gasket is laid around the entire perimeter, forming a chamber for fuel.

The known fuel cell battery has a reduced thickness and increased specific power due to miniaturization of the structure and the relative position of its parts. However, the stability of the current collection during operation of the device is not provided.

A fuel cell is known (see patent RU 2328060, IPC H01M 8/00, published June 27, 2008), including an anode electrode, a cathode electrode, a proton conducting membrane located between the electrodes, an anode and cathode gas diffusion layers, current collectors of at least 2 metal grids. The proton-conducting membrane with electrodes, the anodic and cathodic gas diffusion layers are combined into a single integral membrane-electrode assembly by means of a polymer frame.

Known FC is difficult to manufacture and does not prevent the degradation of electrical contacts during operation.

A known fuel cell battery (see RU 2328060, IPC H01M 8/00, published June 27, 2008), consisting of at least 2 fuel cells, each of which includes an anode electrode, a cathode electrode located between the electrodes of the proton-conducting membrane hydrogen and oxygen (air) gas diffusion collectors, current collectors made of metal grids and a bipolar cooling plate for separating adjacent fuel elements made in the form of a thin plate heat exchanger with a frame and a metal mesh inside Amki, characterized in that the fuel cells are made according to any one of claims 1 to 7, the frame of the bipolar cooling plate is equipped with channels and holes for supplying and distributing reagents (hydrogen, oxygen, air) through the hydrogen and oxygen chambers of the fuel cell and removing reaction products, and the side walls adjacent to the hydrogen and oxygen chambers of the fuel cells are provided with openings for communicating the collector systems of the battery through hydrogen and oxygen (air) with the corresponding gas chamber of the fuel cell.

The known TE battery is difficult to manufacture and does not prevent the degradation of electrical contacts during operation.

A known fuel cell (see application US 20120034542, IPC H01M 8/00, published 09.02.2012), coinciding with this technical solution for the largest number of essential features and adopted for the prototype. The FC includes a membrane-electrode assembly containing a proton-conducting membrane located between the anode gas diffusion layer and the cathode gas diffusion layer. To the anode gas diffusion layer and the cathode gas diffusion layer are adjacent anode and cathode end plates, respectively. A frame is located along the periphery of the membrane-electrode, one relatively elastic gasket and another less elastic gasket.

This design of the known TE makes it possible to stabilize its operation mainly at low pressures, which limits the scope of the known TE. In addition, this design does not provide a stable low electrical resistance during operation of the fuel cell, since the compression of the elements of the fuel cell occurs only along its periphery.

A known fuel cell battery (see patent RU 70051, IPC H01M 8/00, H01M 16/00, published January 10, 2008), which coincides with this technical solution for the largest number of essential features and adopted as a prototype. The prototype battery contains at least two membrane-electrode assemblies directed to each other by anodes and limiting the common fuel chamber, end plates, channels for supplying anode and cathode gases, current leads and means for sealing and connecting these elements. The battery also contains a gas distribution assembly, which includes a dielectric plate with gas distribution channels and anode metal plates fixed on its opposite sides, provided with windows for supplying anode gas to the membrane-electrode assemblies. Membrane-electrode assemblies are hermetically sealed to the gas distribution assembly by means of end plates provided with peripheral and central holes with holes for screws to tighten the battery and windows for supplying cathode gas to the cathodes of the membrane-electrode assemblies.

The coupler of the battery structure is produced by a large number of screws, including the center of the structure. The central screw requires an appropriate hole in the structure and the membrane-electrode block, which degrades the gas-insulating properties and can lead to communication of the anode and cathode spaces, which, in turn, leads to a deterioration in the electrical characteristics of the power source. In addition, this solution increases the complexity of manufacturing the design and adds extra weight. The presence of a central screw helps to maintain electrical contact mainly in the center of the battery, which is not so effective in case of shrinkage of the structural components of the battery.

The objective of this technical solution is to create a design of a fuel cell and a fuel cell battery with increased energy conversion efficiency by reducing losses on the electrical resistance of current-collecting contacts, and increased stability of this resistance over time while maintaining weight and size parameters, labor costs for its manufacture and cost characteristics.

The problem is solved by a group of inventions, united by a single inventive concept.

In terms of the fuel cell, the problem is solved in that the fuel cell includes a membrane-electrode assembly, a plate with gas distribution channels for supplying and removing anode gas located on the anode side of the membrane-electrode assembly, means for tightening the fuel cell, means for sealing in the form of elastic gaskets in the peripheral part of the membrane-electrode assembly and current leads. The membrane-electrode assembly contains a proton-conducting membrane located between the anode gas diffusion layer and the cathode gas diffusion layer, to which the anode and cathode are adjacent, made in the form of an electrically conductive plate with windows for supplying the cathode gas. A new one is the placement between a plate with gas distribution channels for supplying and discharging anode gas and the anode of an elastic plate dielectric strip made of a chemically inert material with a central hole for the passage of the anode gas, the elastic modulus of which is greater than the elastic modulus of the anode and cathode gas diffusion layers.

An elastic plate-like dielectric gasket with a central hole for the passage of the anode gas, which has an elastic modulus greater than the elastic modulus of the gas diffusion layers, compensates for their bursting by constant compression, thereby maintaining a constant surface area of the electrical contacts between the anode and the anode gas diffusion layer, and also between the cathode and the cathode gas diffusion layer, and, consequently, the resistance between them.

The elastic plate-like dielectric gasket may be made of silicone or other resilient plate-like dielectric chemically inert material, for example rubber.

The fuel element may be square, rectangular, round or any other shape, and means for tightening the fuel element may be in the form of latches, rivets, brackets, screws or bolts with nuts passing through holes in the peripheral parts of the fuel element. Screed construction can be done by gluing along the perimeter of the pre-compressed structure.

In terms of the fuel cell battery, the problem is solved in that the fuel cell battery includes at least two membrane-electrode assemblies directed to each other by anodes, between which there is a plate with gas distribution channels for supplying and discharging anode gas. On the outside of each membrane-electrode assembly, the cathodes are made in the form of a plate with windows for supplying cathode gas, equipped with means for tightening the battery. The battery of fuel cells is also equipped with means for sealing in the form of elastic gaskets in the peripheral part of the membrane-electrode assemblies and current leads. A new one is the placement between the plate with gas distribution channels for supplying and discharging the anode gas and the anode of each membrane-electrode assembly of an elastic plate-like dielectric strip made of a chemically inert material with a central hole for the passage of the anode gas, the elastic modulus of which is greater than the elastic modulus of the anode and cathode gas diffusion layers.

The elastic plate-like dielectric gasket may be made of silicone or other resilient plate-like dielectric chemically inert material, for example rubber.

The fuel cell battery may be square, rectangular, round or any other shape, and the means for tightening the fuel cell may be in the form of latches, rivets, brackets, screws or bolts with nuts passing through holes in the peripheral parts of the fuel cell. Screed construction can be done by gluing along the perimeter of the pre-compressed structure.

The elastic plate-like dielectric gasket constantly runs over the assembly due to its elastic properties during operation or storage of the fuel cell battery, which ensures good electrical contact.

The present invention is illustrated by drawings, where:

figure 1 shows a side view of the fuel cell of the present invention;

figure 2 shows a cross section along aa of the fuel cell depicted in figure 1;

figure 3 shows a front view of an elastic plate dielectric gasket;

figure 4 shows a side view of the elastic plate dielectric gasket shown in figure 3;

figure 5 shows a perspective view of a membrane-electrode assembly, divided for clarity into separate elements;

6 is a side view of a fuel cell battery of the present invention;

in Fig.7 shows a cross section along BB of the battery of fuel cells shown in Fig.5;

on Fig depicted on an enlarged scale the node I of Fig.6;

figure 9 shows the dependence of electrical resistance on time of the battery of fuel cells (● - battery of fuel cells of the present invention; ■ - battery of fuel cells without elastic plate gaskets.

The fuel cell 1 of the present invention (see figure 1-figure 4) contains a membrane-electrode assembly 2, consisting of: anode 3 (see figure 5), for example, of aluminum foil, with a current output 4 in the form of a continuation plate anode 3; the first elastic dielectric strip 5 in the form of a frame made of silicone or another elastic plate-like dielectric chemically inert material, for example rubber; the anode gas diffusion layer 6, for example, of carbon porous paper or fabric, placed in the opening of the first elastic dielectric strip 5; proton-conducting membrane 7 with anodic and cathodic catalytic layers, for example, based on a Nation or MF4-SK type membrane and a catalyst based on platinum or other metals, placed between the first elastic dielectric strip 5 and the second elastic dielectric strip 8 in the form of a frame, made of silicone or other an elastic plate-like dielectric chemically inert material, for example rubber; a cathode gas diffusion layer 9, for example, of carbon porous paper or fabric, placed in the opening of the second elastic dielectric strip 8; the cathode in the form of a plate 10 with AND windows for supplying cathode gas (air). An elastic plate dielectric gasket 12 is adjacent to the anode 3 in the fuel cell 1. The elastic plate gasket 12 may be made of silicone or another elastic plate dielectric chemically inert material, for example rubber. In the central region of the gasket 12, a hole 13 is made for the passage of the anode gas (hydrogen) to the membrane-electrode assembly 2. A plate 14 with gas distribution channels 15 and nozzles 16, 17 for supplying and discharging the anode gas is adjacent to the elastic plate gasket 12. Means for tightening the fuel element 1 are made, for example, in the form of screws 19 with nuts 20 passed through the holes 18 in the peripheral sections of the above components of the fuel element 1, and other types of means for tightening the fuel element 1 can be used, such as, for example, screws , brackets, latches or adhesive bonding.

The battery 21 of the fuel cells (see Fig.6-Fig.8) includes at least two membrane-electrode assemblies 2 with cathodes in the form of plates 10 with windows 11 for supplying cathode gas, identical to those described above, directed to each other by anodes 3, between which there is a plate 22 with gas distribution channels 23, 24 and nozzles 16, 17 for supplying and discharging the anode gas, means (for example, screws 19 from the nut 20) for tightening the battery 21. Elastic adjacent to the anodes 3 of the membrane-electrode assemblies 2 plate dielectric pads 12 (see figure 3-figure 4). The elastic plate gasket 12 may be made of silicone or other resilient plate dielectric chemically inert material, for example rubber. In the central region of the gaskets 12, holes 13 are made for the passage of the anode gas (hydrogen) to the corresponding membrane-electrode assembly 2, as well as holes 18 in the peripheral sections of the gaskets 12 for means of coupler of the battery 21.

The fuel cell 1 operates as follows.

Hydrogen is supplied through the nozzle 16 to the anode space of the fuel element 1, through the gas distribution channel 15 of the plate 14, (the nozzle 17 is used for short-term purging of the anode space and is closed in the operating mode). In the porous anode gas diffusion layer 5, hydrogen is evenly distributed and enters the proton-conducting membrane 7 from the side of the anode catalytic layer. An anodic reaction occurs on the anode catalytic layer. As a result, protons and electrons are formed. Protons through the proton conducting membrane 7 enter the cathode catalytic layer. Electrons from the anode catalytic layer pass through the porous cathode gas diffusion layer 9 and from it enter the anode 3, for example, from aluminum foil. From the anode 3, electrons pass through the load to the cathode 10 in the form of a plate with windows 11 for supplying cathode gas (oxygen).

Oxygen is supplied to the cathode space of the fuel cell 1 from the air, through the windows 11 for supplying the cathode gas (oxygen) in the cathode plate 10. Oxygen is uniformly distributed through the porous cathode gas diffusion layer 9 and enters the proton conducting membrane 7 from the side of the cathode catalytic layer. A cathodic reaction occurs on the cathode catalyst layer. As a result, water is formed from oxygen, hydrogen protons passing through the membrane 7 from the anode side, and electrons passing through the load.

The role of the gasket is to constantly pressurize the fuel element 1, which ensures good electrical contact between the anode 3, the porous anode gas diffusion layer 5 and the proton-conducting membrane 7 from the side of the anode catalytic layer, and also between the cathode 10, the porous cathode gas diffusion layer 9 and proton conductive membrane 7 from the side of the cathode catalytic layer.

A fuel cell battery 21 operates in a similar manner.

A sample of the battery was made of two square-shaped fuel cells of size 50 × 50 × 14 mm. In one case, a sample of a battery of two fuel cells did not contain an elastic plate gasket in its design, but in another case it contained. The test results of the fuel cell battery sample of the present invention and the fuel cell battery sample without elastic plate spacers are shown in FIG. 9, which shows the dependence of the electrical resistance of the fuel cell battery on its operating time. As can be seen in Fig.9, the electrical resistance of the fuel cell battery of the present invention with an elastic plate gasket and without gasket at the initial time is the same, but over time, the electrical resistance of the fuel cell battery with an elastic plate gasket does not increase, unlike a fuel cell battery without an elastic plate gaskets. So, for example, in a fuel cell battery without an elastic plate gasket, after 20 minutes, the resistance increased to 5.0 Ohms, and in a fuel cell battery with an elastic plate gasket, the resistance remained at 0.5 Ohm.

Thus, the elastic plate gasket of the present invention allows to maintain a constant surface area of the electrical contacts, and, consequently, the resistance between the anode and cathode gas diffusion layers and, respectively, the anode and cathode.

Claims (6)

1. A fuel cell comprising a membrane-electrode assembly containing a proton-conducting membrane located between the anode gas diffusion layer and the cathode gas diffusion layer, to which the anode and cathode are adjacent, made in the form of an electrically conductive plate with windows for supplying the cathode gas, a plate with gas distribution channels for supply and removal of anode gas, located on the anode side of the membrane-electrode assembly, means for tightening the fuel element, means for sealing in the form of elastic their gaskets in the peripheral part of the membrane-electrode assembly and current leads, characterized in that between the plate with gas distribution channels for supplying and discharging the anode gas and the anode there is an elastic plate dielectric gasket of chemically inert material with a central hole for the passage of the anode gas, the elastic modulus of which more elastic modulus of the anodic and cathodic gas diffusion layers. 2. The fuel cell according to claim 1, characterized in that the elastic plate dielectric gasket is made of silicone. 3. The fuel cell according to claim 1, characterized in that the elastic plate dielectric gasket is made of rubber. 4. A battery of fuel cells, including at least two membrane-electrode assemblies directed to each other by anodes, with cathodes in the form of plates with windows for supplying cathode gas, a plate with gas distribution channels for supply and removal is placed between the membrane-electrode assemblies anode gas, means for tightening the battery, means for sealing in the form of elastic gaskets in the peripheral part of the membrane-electrode assemblies and current outputs, characterized in that between the plate with gas distribution channels I supply and discharge of anode gas and the anode of each membrane-electrode assembly mounted elastic dielectric plate gasket made of chemically inert material with a central hole for the passage of the anode gas, wherein the elastic modulus greater than the elastic modulus of the anode and cathode gas diffusion layers. 5. The battery according to claim 4, characterized in that the elastic plate dielectric gasket is made of silicone. 6. The battery according to claim 4, characterized in that the elastic plate dielectric gasket is made of rubber.

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