CN101335353B - Assembling method for fluid distributing board and current collecting master board of fuel cell - Google Patents

Abstract

The invention relates to an assembly method of a fluid distribution plate and a current collector motherboard of a fuel cell. The method is to open a concave space on one side or both sides of the fluid distribution plate of a fuel cell stack, and insert a collector into the concave space. The current motherboard, and the surface of the embedded current collector motherboard is flush with the side of the fluid distribution plate, and then the corresponding surface of the current guide plate close to the current collector motherboard is bonded and sealed with the non-concave space on the fluid distribution plate, Make the current guide plate closely fit with the current collector motherboard. Compared with the prior art, the invention has the advantages of anti-corrosion, good sealing, small contact resistance, low cost, convenient assembly and disassembly, and the like.

Description

A method for assembling a fluid distribution plate and a current collector motherboard of a fuel cell

technical field

The invention relates to a fuel cell, in particular to an assembly method of a fluid distribution plate and a current collector motherboard of 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 respectively the guide plate of the anode fuel and the guide plate of the cathode oxidant. These guide plates not only serve as current collector plates, but also as mechanical supports on both sides of the membrane electrode. The guide grooves on the guide plates serve as passages for fuel and oxidant to enter the anode and cathode surfaces, and run as a fuel cell. Channels of water generated during the process.

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; As shown in Figure 2 is the guide plate in the existing proton exchange membrane fuel cell single cell, it comprises air inlet 1a, water inlet 2a, hydrogen gas inlet 3a, flow channel 8a, air outlet 5a, water outlet 6a, hydrogen outlet 7a; Figure 3 is a fuel cell stack in which several cells are connected in series, which includes a panel 9a, a first current collector motherboard 10a, a battery stack 11a, a second collector Current motherboard 12a, load 13a; the proton exchange membrane fuel cell stack can be composed of several single cells in series, or several single cells can be connected in series to form a unit, and then several such units can be formed in parallel as shown in Figure 4 A fuel cell stack, which comprises a first current collector motherboard 10a, a cell stack 11a, a second current collector motherboard 12a, and an insulating plate 14a; the proton exchange membrane fuel cell stacks referred to in Fig. 3 and Fig. 4 above all relate to to two or more current collector motherboards, which are respectively positive, negative or negative and positive current collector motherboards in the fuel cell stack. These two current-collecting motherboards 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 collector motherboard, which allow various fluids of the fuel cell to pass freely. The guide plates in the stack are the same size.

At present, in order to achieve the above two effects, the current collector motherboards in various fuel cell stacks 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 motherboard, electrochemical corrosion reactions will not occur 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 motherboard, electrochemical corrosion will occur when various fluids pass through the current collector motherboard, 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 motherboard for fuel cells" (China Patent No. 02265853.X) adopts a cheap and corrosion-resistant current collector Motherboard, this current collector motherboard can be divided into several basic areas: the materials on the current collector motherboard area A and area C are corrosion-resistant non-conductive materials, such as plastics, epoxy resin boards, 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 motherboard 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 motherboard 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 motherboard There should be a sealing device between them to ensure that when the three kinds of incoming and outgoing fluids pass through the diversion holes on the current collector motherboard and the end plate, the fluid will not leak from between the current collector 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. When the fuel cell is integrated, it also involves the sealing of the central current collecting plate, the current collecting mother plate, and the current guiding plate. The process is complicated, the sealing is difficult, and the contact resistance is large.

Contents of the invention

The object of the present invention is to provide a method for assembling a fluid distribution plate and a current collector motherboard of a fuel cell with a compact structure, corrosion resistance and low contact resistance 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 method for assembling a fluid distribution plate and a current collector motherboard of a fuel cell, characterized in that the method is to open one side or both sides of the fluid distribution plate of a fuel cell stack A concave space, in which the current collector motherboard is inlaid, and the surface of the embedded current collector motherboard is flush with the side of the fluid distribution plate, and then the corresponding surface of the current guide plate close to the current collector motherboard is aligned with the The non-concave space on the fluid distribution plate is bonded and sealed, so that the diversion plate and the current collector motherboard are closely attached.

The fuel cell stack includes a single cell stack and an integrated cell stack, and the integrated cell stack includes at least two groups of front, rear, left, right, or upper and lower cells arranged on both sides or the same side of the central collector plate. location of the fuel cell stack.

The fuel cell stack is a single cell stack, and the fluid distribution plate of the single cell stack is the front and rear end plates of the fuel cell stack. A concave space is opened on one side of the front and rear end plates, and a current collector motherboard is embedded in the concave space. , and the surface of the embedded current collector motherboard is flush with the sides of the front and rear end plates, and the concave space positions at both ends of the front and rear end plates of the fuel cell stack are provided with hydrogen inlet and outlet channels, air inlet and outlet channels, and cooling water inlet and outlet channels, and Adhesive layers are arranged beside the channels around the concave space position, so that the front and rear end plates and the adjacent flow guide plates are glued and sealed.

The fuel cell stack is an integrated battery stack, the fluid distribution plate of the integrated battery stack is the central collector plate of the fuel cell stack, and a concave space is opened on both sides of the central collector plate, and a The current collector motherboard, and the surface of the embedded current collector motherboard is flush with the two sides of the central collector plate, and the concave space on both sides of the central collector plate is provided with hydrogen inlet and outlet channels, air inlet and outlet channels, cooling Water flows in and out of the channel, and an adhesive layer is arranged beside the channel around the concave space position, so that the front and rear end plates and the adjacent flow guide plates are glued and sealed.

The two sides of the central current collecting plate are closely connected with the flow guide plate, one side is the air flow channel plate, and the other side is the hydrogen flow channel plate.

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

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

One or both sides of the fluid distribution plate are milled to dig out a concave space according to the shape and size of the current collector motherboard, and the current collector motherboard is embedded in the concave space and bonded with the fluid distribution plate by adhesive fixed.

The current collector motherboard is glued to the concave space of the fluid distribution plate, and the guide plate adjacent to the fluid distribution plate is glued to the peripheral position of the concave space of the fluid distribution plate to form a complex.

Due to the adoption of the above technical scheme, the present invention is to embed the current collector motherboard in the fluid distribution plate, and glue the flow guide plate adjacent to the fluid distribution plate to the fluid distribution plate, so that the flow guide plate and the current collector The motherboards are tightly fitted, and the sealing effect is good. The fluid enters the corresponding fluid holes of the guide plate from the fluid holes on the fluid distribution plate, and will not flow into the current collector motherboard, corrode the current collector motherboard, and keep the current collector motherboard clean. , so that the contact resistance between the current collector plate and the current collector mother plate is small; when multiple stacks are assembled, the side of the current guide plate on both sides of the central current collector plate close to the current collector motherboard is the guide air flow groove The other side of the electrode plate must be the electrode plate of the hydrogen-conducting air flow groove, so that the positive and negative electrodes of the stack on both sides of the central current collector can be directly connected through the central current collector, without the need for additional wires to draw current across the stack. Compared with the prior art, the present invention has the advantages of anti-corrosion, good sealing, small contact resistance, low cost, convenient assembly and disassembly, and the like.

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;

5 is a schematic structural view of a fuel cell stack according to Embodiment 1 of the present invention;

Fig. 6 is a schematic diagram of the structure of the current collecting motherboard in Fig. 5 before being combined with the fluid distribution plate and the guide plate;

Fig. 7 is the structural representation after compounding in Fig. 6;

Fig. 8 is a schematic structural view of the integrated fuel cell stack according to Embodiment 2 of the present invention;

Fig. 9 is a schematic diagram of the structure of the current collecting motherboard in Fig. 8 before being combined with the central current collecting plate and the current guiding plate;

Fig. 10 is a schematic diagram of the composite structure in Fig. 9 .

Detailed ways

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

Example 1

As shown in Figures 5 to 7, a method for assembling a fluid distribution plate and a current collector motherboard of a fuel cell, the fuel cell stack includes a stack 1, a fluid distribution plate, the fluid distribution plate includes a fuel cell stack front plate 21, The rear end plate 22 has a concave space 211 on one side of the front and rear end plates 21, 22, and the current collector motherboards 31, 32 are embedded in the concave space, and the current collector motherboards 31, 32 are respectively glued to the front end plate 21. , the concave space position of the rear end plate 22, and the surface of the embedded current collector motherboard is flush with the side of the front and rear end plates, and the current collector motherboard 31, 32 is provided with a current lead-out ear 311, 321 drawn from the left, The current lead-out ears 311, 321 are provided with connection holes 312, 322, and the non-concave space positions 212 at both ends of the front and rear end plates of the fuel cell stack are provided with hydrogen inlet and outlet channels 41, 42, air inlet and outlet channels 43, 44, cooling Water enters and exits the channels 45, 46, and an adhesive layer 5 is arranged beside the channels, so that the front end plate 21 and the adjacent air-guiding flow channel pole plate 6 are glued and sealed, and the rear end plate 22 is adjacent to the hydrogen-conducting air flow channel pole plate. Sticky seal.

Fig. 6 is a schematic structural view of the front end plate 21 of the fuel cell, the current collector motherboard 31 and the front of the current collector motherboard 31 before it is combined with the adjacent air-conducting flow slot pole plate 6, through the front end plate 21 and the current collector motherboard An adhesive layer is set between 31 to bond the front plate 21 and the current collector motherboard 31, and an adhesive layer is set at the non-concave space position at the two ends of the front plate 21 to guide the air flow groove pole plate 6 and the front plate 21 and The current collector motherboard 31 is glued together to form a composite whole, as shown in FIG. 7 . In the same way, the back end plate 22 current collector motherboard 32 and the front and adjacent air guide slot plate 6 of the current collector motherboard 32 are combined into a whole by gluing.

Example 2

As shown in Figures 8 to 10, a fuel cell integrated with two battery stacks for a forklift includes two battery stacks 1, 1', a fluid distribution plate, and the fluid distribution plate includes a front end plate 21, a rear end plate 22, a central collector Flow plate 23, current collector motherboards 31, 32, 33, current lead-out ears 311, 321, 331 provided on current collector motherboards, connecting holes 312, 322, 332 provided on current lead-out ears, the central collector A rectangular shape is dug out by milling in the middle of both sides of the flow plate 23, about 20cm long, 10cm wide, and 3mm deep; Enter the current collector motherboard 33 in the above-mentioned concave space, coat the current collector motherboard (copper material) 33 with epoxy glue, put it into the above-mentioned concave space and grind it after curing at a high temperature of 80°C, so that the central current collector plate 23 It is on the same plane as the current collector motherboard 33, and the two current collector motherboards 33 on both sides of the central current collector The screw 8 is connected to the corresponding connection hole 332, so that the two battery stacks 1, 1' are connected in series. The non-concave space on both sides of the central collector plate is provided with a hydrogen inlet channel 41, an air inlet channel 43, and a cooling water outlet channel. 46. The front end plate 21 and the rear end plate 22 are provided with a hydrogen outlet channel 42, an air outlet channel 44, and a cooling water inlet channel 45, and an adhesive layer 5 is arranged beside each channel, so that the central collector plate 23 and the The adjacent air-guiding flow channel pole plates 6 and the hydrogen-guiding air flow channel pole plates 7 are glued together to form a composite whole. Figure 9 is a schematic diagram before the composite of the central current collecting plate, the current collecting motherboard, and the current guiding plate, and Figure 10 is a schematic diagram after the composite of the central current collecting plate, the current collecting motherboard, and the current guiding plate.

In addition, the composite method of the front end plate 21, the rear end plate 22, the current collector motherboards 31, 32 and the corresponding current guide plates adjacent to the front of the end plate is the same as above.

The current collector motherboard is embedded in the fluid distribution plate, and the flow guide plate adjacent to the fluid distribution plate is glued to the fluid distribution plate, so that the flow guide plate and the current collector motherboard are closely attached and sealed. The effect is good, the fluid enters the corresponding fluid hole of the guide plate from the fluid hole on the fluid distribution plate, and will not flow into the current collector motherboard, corrode the current collector motherboard, and keep the current collector motherboard clean, so that the guide plate and the The contact resistance of the current collector mother board contact is small; when multiple stacks are assembled, the two sides of the central current collector plate are close to the current guide plate of the current collector mother board. In order to guide the hydrogen flow channel plate, the positive and negative poles of the stacks on both sides of the central current collecting plate can be directly connected through the central current collecting plate, without the need to set additional wires to draw current across the stack.

The fuel cell stack is an integrated battery stack including a single cell stack, two cell stacks are arranged left and right or up and down, four battery stacks are arranged front and back, left and right or up and down, and other multiple battery stacks are arranged front, back, left, right and/or up and down.

Claims (6)

1. An assembly method of a fluid distribution plate and a current collector motherboard of a fuel cell, characterized in that the method is to open a concave space on one side or both sides of the fluid distribution plate of the fuel cell stack, and in the concave space The current collector motherboard is embedded inside, and the surface of the embedded current collector motherboard is flush with the side of the fluid distribution plate, and then the corresponding surface of the current guide plate close to the current collector motherboard is glued to the non-concave space position on the fluid distribution plate Sealing, so that the diversion plate and the current collector motherboard are closely attached; The fuel cell stack includes a single cell stack or an integrated cell stack, and the integrated cell stack includes at least two groups of front, rear, left, right, or upper and lower cells arranged on both sides or the same side of the central collector plate. location of the fuel cell stack; The fuel cell stack is a single cell stack, and the fluid distribution plate of the single cell stack is the front and rear end plates of the fuel cell stack. A concave space is opened on one side of the front and rear end plates, and a current collector motherboard is embedded in the concave space. , and the surface of the embedded current collector motherboard is flush with the sides of the front and rear end plates, and the concave space positions at both ends of the front and rear end plates of the fuel cell stack are provided with hydrogen inlet and outlet channels, air inlet and outlet channels, and cooling water inlet and outlet channels, and Adhesive layers are arranged beside the channels around the concave space position, so that the front and rear end plates are glued and sealed with the adjacent flow guide plates; Alternatively, the fuel cell stack is an integrated battery stack, and the fluid distribution plate of the integrated battery stack is a central collector plate of the fuel cell stack, and a concave space is opened on both sides of the central collector plate, and in the concave space The current collector motherboard is inlaid, and the surface of the embedded current collector motherboard is flush with the two sides of the central current collector plate, and the concave space on both sides of the central current collector plate is provided with hydrogen inlet and outlet channels and air inlet and outlet channels 1. The cooling water enters and exits the channel, and an adhesive layer is arranged beside the channel around the concave space position, so that the front and rear end plates and the adjacent flow guide plates are glued and sealed. 2. The method for assembling a fluid distribution plate and a current collector motherboard of a fuel cell according to claim 1, wherein the current guide plates closely connected to both sides of the central current collector plate are a One side is the polar plate of the air-conducting flow channel, and the other side is the electrode plate of the hydrogen-conducting air flow channel. 3. The method for assembling the fluid distribution plate and the current collector motherboard of a fuel cell according to claim 1, wherein the current collector motherboard is provided with at least one from above or from the left and/or right The drawn current is drawn out of the ears. 4 . The method for assembling the fluid distribution plate and the current collector motherboard of the fuel cell according to claim 3 , wherein at least one connection hole is provided on the current lead-out ear. 5. The method for assembling a fluid distribution plate and a current collector motherboard of a fuel cell according to claim 1, wherein one or both sides of the fluid distribution plate are milled according to the shape and size of the current collector motherboard. A concave space is dug out, and the current collector motherboard is embedded in the concave space and fixed with the fluid distribution plate through adhesive bonding. 6. The method for assembling the fluid distribution plate and the current collector motherboard of a fuel cell according to claim 1, wherein the current collector motherboard is glued to the concave space of the fluid distribution plate, and Adhesive the guide plate adjacent to the fluid distribution plate to the peripheral position of the concave space of the fluid distribution plate to form a complex.

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