CN100444445C - Composite structure of current collector plate and end plate for fuel cell - Google Patents

Abstract

The present invention relates to a flow-collection mother-board and end-board composite structure for fuel cells, which comprises a flow-collection mother board and a flow-collection end board, wherein the inner side surface of the end board is provided with a concave space in which the flow-collection mother board is inlaid, and the surface of the flow-collection mother board is accordant with the inner side surface of the end board after inlaid. Compared with the prior art, the present invention has the advantages of compact structure, high sealing performance, low cost, etc.

Description

Composite structure of current collector plate and end plate for fuel cell

technical field

The invention relates to a fuel cell, in particular to a composite structure of a current collecting mother plate and an end plate for the fuel cell.

Background technique

An electrochemical fuel cell is a device that converts hydrogen and oxidants into electrical energy and reaction products. The internal core component of the device is the membrane electrode (Membrane Electrode Assembly, referred to as MEA). The membrane electrode (MEA) is composed of a proton exchange membrane and two porous conductive materials, such as carbon paper, sandwiched between the two sides of the membrane. On the two boundary surfaces of the membrane and the carbon paper, there are even and finely dispersed catalysts for initiating electrochemical reactions, such as metal platinum catalysts. Conductive objects can be used on both sides of the membrane electrode to draw the electrons generated during the electrochemical reaction through an external circuit to form a current loop.

At the anode end of the membrane electrode, the fuel can permeate through the porous diffusion material (carbon paper), and an electrochemical reaction occurs on the surface of the catalyst, losing electrons and forming positive ions, which can migrate through the proton exchange membrane, Reach the cathode end of the other end of the membrane electrode. At the cathode end of the membrane electrode, a gas containing an oxidant (such as oxygen), such as air, penetrates through the porous diffusion material (carbon paper), and electrochemically reacts on the surface of the catalyst to obtain electrons to form negative ions. Anions formed at the cathode end react with positive ions migrating from the anode end to form reaction products.

In a proton exchange membrane fuel cell that uses hydrogen as fuel and air containing oxygen as the oxidant (or pure oxygen as the oxidant), the catalytic electrochemical reaction of fuel hydrogen in the anode region produces positive hydride ions (or protons). The proton exchange membrane facilitates the migration of positive hydride ions from the anode region to the cathode region. In addition, the proton exchange membrane separates the hydrogen-containing fuel gas stream from the oxygen-containing gas stream so that they do not mix with each other and cause an explosive reaction.

In the cathode area, oxygen gets electrons on the surface of the catalyst to form negative ions, and reacts with positive hydrogen ions migrated from the anode area to generate water as a reaction product. In a proton exchange membrane fuel cell using hydrogen and air (oxygen), the anode reaction and cathode reaction can be expressed by the following equation:

Anode reaction: H ₂ → 2H ⁺ +2e

Cathode reaction: 1/2O ₂ +2H ⁺ +2e→H ₂ O

In a typical proton exchange membrane fuel cell, the membrane electrode (MEA) is generally placed between two conductive plates, and the surface of each guide plate in contact with the membrane electrode is formed by die-casting, stamping or mechanical milling to form at least More than one diversion groove. These current guide plates can be made of metal or graphite. The fluid channels and flow guide grooves on these guide plates guide the fuel and oxidant into the anode area and the cathode area on both sides of the membrane electrode respectively. In the structure of a single proton exchange membrane fuel cell, there is only one membrane electrode, and the two sides of the membrane electrode are the deflectors of the anode fuel and the cathode oxidant respectively. These deflectors are not only used as current collectors, but also as mechanical supports on both sides of the membrane electrodes. The guide grooves on the deflectors are also used as passages for fuel and oxidant to enter the anode and cathode surfaces, and as a way to take away fuel cells during the operation of the fuel cell. Channels for the resulting water.

In order to increase the total power of the entire proton exchange membrane fuel cell, two or more single cells can usually be stacked in series to form a battery pack or connected in a tiled manner to form a battery pack. In direct-stacked and series-connected battery packs, there can be diversion grooves on both sides of a pole plate, one of which can be used as the anode diversion surface of one membrane electrode, and the other side can be used as the cathode of another adjacent membrane electrode. The diversion surface, this kind of plate is called a bipolar plate. A series of cells are connected together in a certain way to form a battery pack. The battery pack is usually fastened together by the front end plate, the rear end plate and the tie rods to form a whole.

A typical battery pack usually includes: (1) diversion inlet and diversion channel of fuel and oxidant gas, fuel (such as hydrogen, methanol or methanol, natural gas, hydrogen-rich gas obtained by reforming gasoline) and oxidant (mainly Oxygen or air) is evenly distributed into the diversion grooves of each anode and cathode surface; (2) the inlet and outlet of the cooling fluid (such as water) and the diversion channel, the cooling fluid is evenly distributed into the cooling channels in each battery pack, Absorb the heat generated by the electrochemical exothermic reaction of hydrogen and oxygen in the fuel cell and take it out of the battery pack for heat dissipation; (3) the outlet of the fuel and oxidant gas and the corresponding guide channel, when the fuel gas and oxidant gas are discharged, can Carry out the liquid and vapor state water generated in the fuel cell. Usually, the inlets and outlets of all fuels, oxidants, and cooling fluids are opened on one or both end plates of the fuel cell stack.

Proton exchange membrane fuel cells can be used not only as power systems for vehicles, ships and other vehicles, but also as mobile or fixed power stations.

Proton exchange membrane fuel cells are generally composed of several single cells. These single cells are connected in series or parallel to form a proton exchange membrane fuel cell stack, and the proton exchange membrane fuel cell stack is combined with other operating support systems to form the entire proton exchange membrane fuel cell stack. Exchange membrane fuel cell power generation system.

Fig. 1 is the membrane electrode in the existing proton exchange membrane fuel cell single cell, and it comprises air inlet 1a, water inlet 2a, hydrogen gas inlet 3a, electrode active area 4a, air outlet 5a, water outlet 6a, Hydrogen gas outlet 7a; Fig. 2 is the guide plate in the existing proton exchange membrane fuel cell single cell, and it comprises air inlet 1a, water inlet 2a, hydrogen gas inlet 3a, runner 8a, air outlet 5a, water outlet 6a, hydrogen gas outlet 7a; Figure 3 is a fuel cell stack in which several single cells are connected in series, which includes a panel 9a, a first collector board 10a, a battery stack 11a, a second collector flow mother board 12a, load 13a; proton exchange membrane fuel cell stack can be made up of several single cells in series, also can form a unit by several single cells in series, then several such units are formed in parallel form as shown in Figure 4 Fuel cell stack, this fuel cell stack comprises the first current collecting motherboard 10a, cell stack 11a, the second current collecting motherboard 12a, insulating plate 14a; The proton exchange membrane fuel cell stack referred to in Fig. 3 and Fig. 4 above all relate to To two or more collector motherboards, which are respectively positive, negative or negative and positive collector motherboards in the fuel cell stack. These two collector boards have the following two functions:

1. Draw out the current of several fuel cell single cells connected in series or in parallel or the entire fuel cell stack to form the positive and negative poles that conduct the current of the external circuit;

2. There are also various fluid channel holes on the current collecting motherboard, which can allow various fluids of the fuel cell to pass freely, as shown in Figure 5, 1a, 2a, 3a, 5a, 6a, 7a are fluid holes, and 15a is the ear of the current lead-out end , 10a is the current collecting motherboard, so the size of the current collecting motherboard is basically the same as that of the guide plate in the fuel cell stack except for the ears of the two current lead-out ends, and the fluid holes on the top are also the same as those on the guide plate The diversion holes are the same size to form the diversion channels of the entire fuel cell stack.

At present, in order to achieve the above two effects, the current collector plates in various fuel cell stacks all use very special materials, such as metal gold, metal platinum, or other metals such as stainless steel, copper, aluminum, gold plating, and platinum. Using these materials, the electrical conductivity is very good, and when various fluids pass through the current collector, there will be no electrochemical corrosion reaction to produce metal ions that are harmful to the fuel cell. However, these materials such as precious metals such as gold and platinum are very expensive, and electroplating on other metals such as copper, stainless steel, and aluminum is also expensive and inconvenient.

If stainless steel, metal copper, and aluminum are directly used as the current collector plate, electrochemical corrosion will occur when various fluids pass through the current collector plate, and metal ions that are harmful to the fuel cell will be produced.

In order to overcome the above-mentioned technical defects, the patent of Shanghai Shenli Technology Co., Ltd. "A high-efficiency anti-corrosion composite current collector for fuel cells" (China Patent No. 02265853.X) adopts a cheap and corrosion-resistant current collector Motherboard, this kind of current collecting motherboard can be divided into several basic areas: the materials on the current collecting motherboard area A and area C are corrosion-resistant non-conductive materials, such as plastic, epoxy resin board, glass, etc., while area B The material on the surface is an excellent conductive material, such as aluminum, copper, zinc, titanium, area A, area C and area B are bonded together in a certain way, and can be isolated from each other by sealing materials, allowing various fluids to pass through area A When it is connected with area C, it will not leak into area B, so that area B can be completely isolated from media such as air and water, and the current-collecting conduction will not cause electrochemical corrosion reactions. In case of corrosion, the generated ions will not leak into each other. Contaminate the fuel cell through fluid passages. Each region of this composite current collector is equal in thickness.

However, this high-efficiency anti-corrosion composite current collector technology also has certain technical defects:

1. This high-efficiency anti-corrosion composite current collector is composed of different materials in different regions, which is inconvenient to manufacture;

2. When the fuel cell stack is assembled, if there are inlets and outlets of fuel hydrogen, oxidant air, and cooling fluid on the front end plate or rear end plate of the fuel cell stack, then the distance between the front end plate and the rear end plate of the fuel cell and the current collector There should be a sealing device in between to ensure that when the three kinds of incoming and outgoing fluids pass through the diversion holes on the collecting motherboard and the end plate, the fluid will not leak out from between the collecting motherboard and the end plate, and this sealing The device is often a rubber sealing ring, which is not only troublesome, but also prone to aging and failure during repeated disassembly and assembly.

Contents of the invention

The object of the present invention is to provide a composite structure of a current collector plate and an end plate for a fuel cell with a compact structure and good sealing performance in order to overcome the above-mentioned defects in the prior art.

The purpose of the present invention can be achieved through the following technical solutions: a composite structure of a current collector plate and an end plate for a fuel cell, comprising a current collector plate and an end plate, characterized in that the inner surface of the end plate There is a concave space, and the current collecting motherboard is embedded in the concave space, and the surface of the embedded current collecting motherboard is flush with the inner surface of the end plate.

The end plate includes a front end plate and a rear end plate, and the non-concave space position of the front end plate is provided with hydrogen inlet and outlet channels, air inlet and outlet channels, and cooling water inlet and outlet channels.

The current collecting motherboard is provided with at least one current lead-out ear drawn from above or from the left and/or right.

At least one connection hole is provided on the current lead-out ear.

The inner surface of the end plate is milled and dug out a concave space according to the shape and size of the current collecting motherboard, and the current collecting motherboard is embedded in the concave space and fixed with the end plate by adhesive to form a current collecting Motherboard and end plate complex.

The current collecting motherboard is placed in the mould, and the composite body of the current collecting motherboard and the end plate is formed by a pouring molding process.

The current collecting mother plate and the end plate materials are placed in the mould, and the current collecting mother plate and the end plate composite are formed by a compression molding process.

The end plates are made of corrosion-resistant non-conductive materials, including plastics, epoxy resin, and ceramics.

The current collecting motherboard is made of excellent conductive materials, including aluminum, copper, zinc, and titanium.

The surface of the conductive material can also be plated with a thin layer of gold.

The present invention adopts the above technical scheme, that is, the current collecting mother plate is made of a single material (excellent conductive material) and embedded in the end plate, so it overcomes the need for sealing between the current collecting mother plate and the end plate in the prior art and the The current collector motherboard is made of two kinds of materials to produce defects. Compared with the prior art, the invention has the advantages of compact structure, good sealing and low cost.

Description of drawings

FIG. 1 is a schematic structural view of a membrane electrode in an existing fuel cell;

Fig. 2 is a schematic structural view of a current guide plate in a conventional fuel cell;

Fig. 3 is a structural schematic diagram of a fuel cell stack composed of several single cells connected in series;

Fig. 4 is a structural schematic diagram of a fuel cell stack composed of several single cells connected in parallel;

FIG. 5 is a schematic structural view of an existing current collecting motherboard;

Fig. 6 is a structural schematic diagram of a combination of a current collecting motherboard and a front-end plate in the present invention;

Fig. 7 is the right view of Fig. 6;

Fig. 8 is a structural schematic diagram of another combination of current collecting motherboard and front-end plate of the present invention;

Fig. 9 is the right view of Fig. 8;

Fig. 10 is a schematic structural diagram of a combination of a current collecting motherboard and a rear end plate according to the present invention;

Fig. 11 is A-A sectional view of Fig. 10;

Fig. 12 is a structural schematic diagram of a fuel cell stack composed of a composite structure of a current collecting motherboard and an end plate and several single cells of the present invention.

In the above-mentioned drawings, the oblique lines in Fig. 6 to Fig. 10 represent the end plates, and the oblique lines in Fig. 11 represent both the end plates and also serve as section lines.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Example 1

As shown in Fig. 6 and Fig. 7, a composite body of a collector motherboard and a front-end plate for a fuel cell. The complex includes a conductive active block 1, a non-conductive material epoxy resin plate 2, and the non-conductive material epoxy resin plate 2 is used as the front end plate of the fuel cell stack, wherein the air inlet channel 21, the cooling water inlet channel 22, The hydrogen inlet channel 23, the air outlet channel 25, the cooling water outlet channel 26, and the hydrogen outlet channel 27 are all arranged on the upper and lower parts of the front plate, and a rectangular shape is dug out in the middle part of the front plate, about 20cm long, 10cm wide, and 3mm deep The concave space; the conductive active block 1 is used as the current collecting motherboard, the current collecting motherboard is 20cm long, 10cm wide, and about 2.9mm thick, which can just fit into the above concave space, and at the left and right ends There are symmetrical current lead-out ears 11, and the current lead-out ears are provided with connection holes 111; the current collecting motherboard (copper material) is coated with epoxy glue and put into the above-mentioned concave space and ground after curing at a high temperature of 80°C. Just make the end plate and the current collecting mother plate in the same plane.

In addition, the composite method of the rear end plate and the current collecting motherboard is the same as above, as shown in Figure 10 and Figure 11, consisting of the front end plate and the current collecting motherboard composite, several single cells, the rear end plate 2' and the current collecting motherboard 1 'Composite together constitute a fuel cell stack, as shown in Figure 12.

Example 2

As shown in Fig. 8 and Fig. 9, another composite body of a current collector board and a front-end board for a fuel cell. The complex includes a conductive active block 1, a non-conductive epoxy resin plate 2; the non-conductive epoxy resin plate 2 is used as the front end plate of the fuel cell stack, wherein air enters the channel 21, cooling water enters the channel 22, and hydrogen enters the Tunnel 23, air outlet tunnel 25, cooling water outlet tunnel 26, and hydrogen outlet tunnel 27 are all located on the four corners of the front end plate (2).

The composite body is put into a mold by hexagonal red copper plate 1 (i.e. the above-mentioned conductive active block 1) with two symmetrical current lead-out ears 11, poured with epoxy resin, solidified and formed, and smoothed After that, the two parts of the complex become the same plane. Other aspects are the same as in Example 1.

Claims (6)

1. one kind is used for the flow-collection mother-board of fuel cell and the composite construction of end plate, comprise flow-collection mother-board, end plate, it is characterized in that, described end plate medial surface has a concave shaped space, described flow-collection mother-board is embedded in this concave shaped space, and the surface of the flow-collection mother-board after embedding is concordant with the end plate medial surface; Described end plate medial surface mills by the geomery of flow-collection mother-board and digs out a concave shaped space, and described flow-collection mother-board is embedded in this concave shaped space and with end plate and is adhesively fixed by adhesive, forms flow-collection mother-board and end plate complex; Described end plate comprises front end-plate, end plate, and the non-concave shaped space position of described front end-plate is provided with hydrogen turnover duct, air turnover duct, cooling water turnover duct.

2. a kind of flow-collection mother-board of fuel cell and composite construction of end plate of being used for according to claim 1 is characterized in that, described flow-collection mother-board is provided with at least one and draws ear from left and/or right electric current of drawing.

3. a kind of flow-collection mother-board of fuel cell and composite construction of end plate of being used for according to claim 2 is characterized in that described electric current is drawn ear and is provided with at least one connecting hole.

4. a kind of flow-collection mother-board of fuel cell and composite construction of end plate of being used for according to claim 1 is characterized in that described end plate adopts corrosion-resistant non-conducting material, is plastics, epoxy resin or pottery.

5. a kind of flow-collection mother-board of fuel cell and composite construction of end plate of being used for according to claim 1 is characterized in that, described flow-collection mother-board adopts good electric conducting material, is aluminium, copper, zinc or titanium.

6. a kind of flow-collection mother-board of fuel cell and composite construction of end plate of being used for according to claim 5 is characterized in that, described electric conducting material surface plates the thin gold of one deck.

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