CN1815781A - Apparatus for pressing membrane electrode for fuel cell pile - Google Patents

Abstract

The invention relates to a pressing device for a membrane electrode used in a fuel cell stack, comprising a base, a bottom plate, a top plate, a movable plate, a support rod, an upper backing plate, a lower backing plate and a drive controller. The bottom plate is arranged on the base, and the The support rod supports and fixes the base plate and the top plate, the movable plate is arranged between the base plate and the top plate and is threaded on the support rod, the upper backing plate is attached to the bottom of the top plate, and the lower backing plate is attached to the bottom of the top plate. Located on the upper surface of the movable plate, the top plate and the movable plate are provided with a heating device, which can accurately control the temperature of the top plate and the movable plate, and the driving controller drives the movable plate to move up and down along the support rod. Compared with the prior art, the invention can significantly improve the processing quality of membrane electrode products.

Description

A pressing device for a membrane electrode for a fuel cell stack

technical field

The invention relates to a fuel cell, in particular to a pressing device for a membrane electrode used in a fuel cell stack.

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:

Cathode reaction:

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.

The membrane electrode is the core component of the fuel cell stack. As shown in Figure 1, the membrane electrode a is formed by attaching a carbon paper a2 to each side of the proton exchange membrane a1 and pressing it with a pressing device. It is also called a three-in-one electrode. Its production process requires high requirements, and the quality of each processing process directly affects the performance of the electrode, especially the last process - pressing and forming. The existing pressing device generally presses the three-in-one electrode directly on the pressing contact surface of the press. The pressing device with this structure will cause mutual pollution between the electrode and the pressing contact surface, thereby affecting the quality of the membrane electrode product. Therefore, we It is necessary to further improve and perfect the pressing device.

Contents of the invention

The object of the present invention is to provide a pressing device for a membrane electrode for a fuel cell stack in order to overcome the above-mentioned defects in the prior art. The pressing device can significantly improve the processing quality of membrane electrode products.

The purpose of the present invention can be achieved through the following technical solutions: a pressing device for a membrane electrode for a fuel cell stack, comprising a base, a bottom plate, a top plate, a movable plate, a support rod and a drive controller, the bottom plate is arranged on the base, The support rod supports and fixes the bottom plate and the top plate, the movable plate is set between the bottom plate and the top plate and is threaded on the support rod, and the drive controller drives the movable plate to move up and down along the support rod. In that, it also includes an upper backing plate and a lower backing plate, the upper backing plate is attached to the bottom of the top plate, the lower backing plate is attached to the upper surface of the movable plate, and the top plate and the movable plate are provided with heating devices, The heating device can precisely control the temperature of the top plate and the movable plate.

It also includes an upper buffer and a lower buffer, the upper buffer is arranged on the bottom of the top plate, the upper backing plate is attached to the bottom of the upper buffer, the lower buffer is arranged on the upper part of the movable plate, and the lower backing is attached to the bottom of the upper buffer. on the upper surface of the lower buffer.

The upper and lower cushioning parts can be steel plates with spring pads, or steel plates with elastic material pads such as rubber.

The upper backing plate or the lower backing plate includes materials selected from niobium, aluminum, graphite, and titanium.

The upper and lower pads or the upper and lower cushioning parts are materials with good thermal conductivity.

Both ends of the support rod are provided with threads, and the support rod is connected and fixed with the bottom plate and the top plate through nuts.

There are at least three support rods.

There are four support rods.

The invention adopts a backing plate made of niobium, aluminum, graphite or titanium, sandwiches the membrane electrode to be pressed, and then puts them together on a pressing platform of a pressing device for pressing. The device has the following advantages:

1. It can prevent the pressing contact surface of the membrane electrode to be pressed from being chemically corroded, and improve the performance of the membrane electrode.

2. It can prevent the pressing surface of the press from being dirty, rusted or damaged, prolong the service life of the press, and ensure the precision of the press, and finally ensure the quality of the membrane electrode.

Description of drawings

Fig. 1 is the structural representation of the three-in-one membrane electrode to be pressed;

Fig. 2 is a structural schematic diagram of the three-in-one membrane electrode and the upper and lower backing plates of the present invention in working state;

Fig. 3 is a structural schematic diagram of the three-in-one membrane electrode and the pressing device of the present invention in working state.

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. 2 and Fig. 3, a pressing device for a membrane electrode for a fuel cell stack includes a base 1, a bottom plate 2, a top plate 3, a movable plate 4, a support rod 5, an upper backing plate 6, a lower backing plate 7 and a drive The controller (not shown in the figure), the base plate 2, the top plate 3, the movable plate 4, the upper backing plate 6, and the lower backing plate 7 are all rectangular, and the size is 400mm×400mm, and the bottom plate 2 is located on the base 1 Above, the four supporting rods 5 are provided with threads, and the four corners of the bottom plate 2 and the top plate 3 are connected and fixed by nuts, and the movable plate 4 is arranged between the bottom plate 2 and the top plate. 3, its four corners are set on the support rod 5, the drive controller drives the movable plate 4 to move up and down along the support rod 5, the upper backing plate 6 is attached to the bottom of the top plate 3, and the lower The backing plate 7 is pasted on the upper surface of the movable plate 4, and the upper backing plate 6 and the lower backing plate 7 all adopt niobium plates with good thermal conductivity, and the thickness of the niobium plates is 0.1～2mm. The plate 4 is provided with a heating device (not shown in the figure), which can precisely control the temperature of the top plate 3 and the movable plate 4 . When the device is in use, first place the three-in-one membrane electrode to be pressed with a size of 200mm×200mm between the upper backing plate 6 and the lower backing plate 7, and then start the drive controller to drive the movable plate 4 upward to stick to the top plate 3 The temperature of the upper backing plate 6 and the lower backing plate 7 is controlled at 120° C., and the pressure of the pressing device is 10-100 kg/cm ² .

Example 2

As shown in Fig. 2 and Fig. 3, a pressing device for a membrane electrode for a fuel cell stack includes a base 1, a bottom plate 2, a top plate 3, a movable plate 4, a support rod 5, an upper backing plate 6, a lower backing plate 7, an upper Buffer 8, lower buffer 9 and drive controller (not shown), the bottom plate 2, top plate 3, movable plate 4, upper backing plate 6, lower backing plate 7, upper buffer 8, lower buffer 9 All are rectangular, with a size of 400mm×400mm. The base plate 2 is arranged on the base 1, and four support rods 5 are provided. Threads are provided at both ends of the four support rods 5, and the base plate 2 is connected by nuts. , The four corners of the top plate 3 are connected and fixed, the movable plate 4 is arranged between the bottom plate 2 and the top plate 3, and its four corners are set on the support rod 5, and the drive controller drives the movable plate 4 to move up and down along the support rod 5 Moving, the upper cushioning part 8 is located at the bottom of the top plate 3, the upper backing plate 6 is attached to the bottom of the upper cushioning part 8, the lower cushioning part 9 is located at the top of the movable plate 4, and the lower backing plate 7 is attached to the bottom of the upper cushioning part 8. On the upper surface of the lower cushioning member 9, the upper backing plate 6 and the lower backing plate 7 adopt niobium plates with good thermal conductivity, and the thickness of the niobium plates is 0.1 to 2mm. A rubber plate with high precision and good thermal conductivity is used. The top plate 3 and the movable plate 4 are provided with a heating device (not shown), which can accurately control the temperature of the top plate 3 and the movable plate 4. When the device is in use, first place the three-in-one membrane electrode to be pressed with a size of 200mm×200mm between the upper backing plate 6 and the lower backing plate 7, and then start the drive controller to drive the movable plate 4 upward to stick to the top plate 3 The temperature of the upper backing plate 6 and the lower backing plate 7 is controlled at 120° C., and the pressure of the pressing device is 10-100 kg/cm ² . The upper and lower buffer members in this embodiment can play the role of buffering and stabilizing, and can further improve product quality.

Claims (8)

1. A pressing device for a fuel cell stack membrane electrode, comprising a base, a base plate, a top plate, a movable plate, a support rod and a drive controller, the base plate is arranged on the base, and the support rod supports the base plate and the top plate fixed, the movable plate is set between the bottom plate and the top plate and penetrates on the support rod, the drive controller drives the movable plate to move up and down along the support rod, and it is characterized in that it also includes an upper backing plate, a lower backing The upper backing plate is attached to the bottom of the top plate, the lower backing plate is attached to the upper surface of the movable plate, and the top plate and the movable plate are provided with a heating device, which can precisely control the heating of the top plate and the movable plate. temperature. 2. The pressing device of a membrane electrode for a fuel cell stack according to claim 1, further comprising an upper buffer and a lower buffer, the upper buffer is arranged at the bottom of the top plate, and the upper backing plate is pasted It is arranged on the bottom of the upper buffer, the lower buffer is arranged on the upper part of the movable plate, and the lower backing plate is attached to the upper surface of the lower buffer. 3. The pressing device of a membrane electrode for a fuel cell stack according to claim 2, wherein the upper and lower buffer members can be steel plates with spring pads, or rubber and other elastic material pads. steel plate. 4 . The pressing device of a membrane electrode for a fuel cell stack according to claim 1 , wherein the upper backing plate or the lower backing plate is made of materials selected from niobium, aluminum, graphite, and titanium. 5. A pressing device for membrane electrodes for fuel cell stacks according to claim 1 or 2, characterized in that said upper and lower backing plates or upper and lower buffer members are made of materials with good thermal conductivity. 6 . A pressing device for a membrane electrode for a fuel cell stack according to claim 1 , wherein threads are provided at both ends of the support rod, and the support rod is connected and fixed to the bottom plate and the top plate through nuts. 7 . 7 . The pressing device of a membrane electrode for a fuel cell stack according to claim 1 , wherein at least three support rods are provided. 8 . 8. A pressing device for a membrane electrode for a fuel cell stack according to claim 1 or 7, characterized in that four support rods are provided.

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