CN100583494C - Fuel cell seal assembly structure - Google Patents

Abstract

The invention relates to a novel fuel cell sealing component structure, including a flow guide plate or a bipolar plate, a membrane electrode, and a sealing ring. In the tank, the sealing ring is set in two areas, one is set at the junction of the inner side of the plate and the membrane electrode, the sealing ring in this area is zigzag up and down, and the inner side is provided with a tongue-shaped opening that matches the membrane electrode. The membrane electrode is inserted into the tongue-shaped opening, and the upper and lower bipolar plates are pressed together to squeeze the sealing ring through the integrated packaging, so that the tongue-shaped opening bites the membrane electrode and seals; At the sealing groove on the edge of the hole, the sealing ring here is zigzag up and down, and is sealed by pressing and extruding the sealing ring between the upper and lower polar plates or bipolar plates during integrated packaging. Compared with the prior art, the present invention has the advantages of free replacement of electrodes, reduced loss, lower reduction and the like.

Description

Fuel cell seal assembly structure

technical field

The invention relates to a battery sealing method, in particular to an electrochemical novel fuel cell sealing component structure.

Background technique

An electrochemical fuel cell is a device that converts hydrogen fuel and oxidant 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 conductive plate in contact with the membrane electrode is formed by die-casting, stamping or mechanical milling to form at least one above the diversion tank. These conductive plates can be plates of metal material or plates of graphite material. The diversion channels and diversion grooves on these conductive plates guide the fuel and the oxidant into the anode region and the cathode region 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 for fuel and oxidant gas, where fuel (such as hydrogen, methanol or hydrogen-rich gas obtained by reforming methanol, natural gas and 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 and diversion channels of the cooling fluid (such as water), and 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 to dissipate heat; (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 positive hydrogen ions in the anode region migrate through the proton exchange membrane, and usually need to carry a large number of water molecules to pass through. Therefore, water molecules must be kept on both sides of the membrane so that the migration conductance of the positive hydrogen ions will not be affected. Therefore, the fuel and oxidant gas must be humidified before entering the active area of the fuel cell to react, so as to ensure that the membrane in the membrane electrode is in a state of water saturation.

In order to ensure that the fuel and oxidant gas in the proton exchange membrane fuel cell can be distributed to the surface of both sides of the entire membrane electrode without mixing, the sealing technology is very critical. If the seal is not good, two situations may occur. One situation is that the fuel gas and the oxidant gas are mixed inside the fuel cell. In a fuel cell that uses hydrogen and oxygen to operate, this mixing is very fatal. Once an explosion occurs, The destructive power is very large; another situation is that the fuel gas or oxidant gas leaks to the outside of the fuel cell. explode.

In a common fuel cell, the membrane electrode is prepared by using the area of the proton exchange membrane much larger than the porous support material in the membrane electrode, such as carbon paper, and the exposed membrane is not the active area of the electrochemical reaction, but the electrode Two sheets of carbon paper are respectively pressed together on both sides of the membrane in the chemically active area. In this method, the membrane electrode is placed between the two guide plates, and the exposed membrane is directly used as the base material of the sealing material, and it prevents the two adjacent guide plates from directly contacting and short-circuiting. . This design method has the following defects:

(1) The water absorption and contraction of the proton exchange membrane are different under different operating states of the fuel cell (such as low temperature, how much water is generated, gas humidity, etc.), especially when the battery is transferred from a non-operating state or a long-term non-operating state to an operating state Under normal circumstances, the degree of expansion and contraction of the membrane is greater, which will lead to aging, rupture, and leakage after a long time.

(2) The proton exchange membrane is generally a relatively expensive material. After being exposed in large quantities, it is not fully utilized and is seriously wasted.

(3) The proton exchange membrane is a corrosive material with strong acid. It is in long-term contact with the sealing ring on the guide plate, and chemical reactions will inevitably occur.

(4) The proton exchange membrane is easily aged and ruptured directly under the pressure of the guide plate. In addition, if a very thin proton exchange membrane is used to make the membrane electrode, even if the power generation efficiency of the membrane electrode will be greatly improved, the above situation will be more serious, so this design can hardly use a very thin proton exchange membrane to make the membrane electrode .

(5) This design also requires that each guide electrode plate needs to be accurately engraved with a sealing groove for placing a sealing ring.

Shanghai Shenli Technology Co., Ltd. provides a new type of fuel cell sealing assembly structure (invention patent application number 01105975.3, utility model patent application number 01238847.5) in order to overcome the above-mentioned defects in the prior art. It is characterized in that it includes the following process steps: first The first step is to use the proton exchange membrane, catalyst, and porous carbon paper to press the effective part of the membrane electrode, which is called part A. The porous carbon paper on the part A is 1 mm to 10 mm shorter than the proton exchange membrane or the same length; The second step is to make the extended casing part of the above-mentioned part A, which is called part B; the third step is to join the two parts A and B to form a complete membrane electrode; the fourth step is to make the diversion plate and conduct it A sealing ring is provided around the pole plate, or a sealing device is provided in part B; in the fifth step, the two guide plates are relatively pasted and the above-mentioned membrane electrode is clamped in the middle to form a seal of the fuel cell unit.

However, in this sealing method, the materials of the sealing assembly and the three-in-one electrode are different, and the technical requirements for mutual bonding are very high, and the thickness of the transfer zone after the two parts are bonded is almost the same as the thickness of the original two parts. It also increases the difficulty of bonding, and only when the two parts cooperate well can the sealing effect be achieved.

Shanghai Shenli Technology Co., Ltd. provides an improved fuel cell assembly (invention patent application number 03141812.0, utility model patent application number 03255926.7) in order to overcome the above defects. A direct seal produces a complete assembly. The middle of the section of the flow-guiding bipolar plate is a cooling fluid groove, and the two sides are respectively a hydrogen-guiding airflow groove and an air-guiding flow groove, and the groove surface of the hydrogen-guiding airflow groove is glued and sealed with the anode surface of the membrane electrode , thus forming a fuel cell stack assembly.

However, in this sealing method, it is very difficult to bond the membrane electrode and the bipolar plate.

Contents of the invention

The object of the present invention is to provide a novel fuel cell sealing assembly structure that can be freely disassembled and has 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 new type of fuel cell sealing assembly structure, including a guide plate or a bipolar plate, a membrane electrode, and a sealing ring, characterized in that the lower end of the sealing ring is glued to the guide In the sealing groove of the hydrogen-conducting anode surface of the polar plate or bipolar plate, the sealing ring is set in two areas, one is set at the junction of the inner side of the polar plate and the membrane electrode, and the sealing ring in this area is zigzag up and down. There is a tongue-shaped opening matching the membrane electrode on the inner side, and the membrane electrode is inserted into the tongue-shaped opening, and the upper and lower bipolar plates are pressed together to squeeze the sealing ring through the integrated packaging, so that the tongue-shaped opening bites the membrane electrode and seals; One is arranged at the sealing groove at the edge of each diversion hole of the polar plate or bipolar plate, where the sealing ring is zigzag up and down, and is sealed by pressing and extruding the sealing ring of the upper and lower polar plates or bipolar plates during integrated packaging.

The membrane electrode may or may not be provided with a frame, and the area of the intermediate proton exchange membrane is slightly extended or equal to that of the porous support material layer in the membrane electrode, so that the membrane electrode is inserted into the tongue-shaped opening of the sealing ring in a tongue shape around the membrane electrode.

The sealing ring is made of elastic and stretchable material, and the upper and lower diversion plates or bipolar plates squeeze the sealing ring to clamp the membrane electrode. Seal tightly.

The sealing ring includes at least one sawtooth up and down, and the protruding part of the sawtooth is bonded to the hydrogen-conducting anode surface of the flow-guiding plate or the bipolar plate, and the bonding method can be formed by one-time casting through a rubber mold.

The sealing ring is zigzag up and down, and the zigzag includes arc shape, V shape and rectangle shape.

The membrane electrodes can be freely taken out and replaced.

Compared with the prior art, the hydrogen-conducting anode surface sealing groove of the bipolar plate of the present invention uses a mold to cast a sealing ring to form a fixed structure. This structure cooperates with the three-in-one membrane electrode assembly to form a tongue shape up and down, and is squeezed up and down to achieve The sealing effect, if damaged, can be replaced freely to reduce losses, and the membrane electrode does not have a frame, which reduces costs and provides guarantee for mass production.

Description of drawings

FIG. 1 is a schematic structural diagram of an existing battery stack sealing assembly;

Fig. 2 is a partial structural schematic view before the membrane electrode of the present invention is sealed;

Fig. 3 is a partial structural schematic diagram after the membrane electrode of Fig. 2 is sealed;

Fig. 4 is a partial structural schematic diagram of the electrode plate frame seal of the present invention;

Fig. 5 is a schematic diagram of part of the structure after the frame of the electrode plate in Fig. 4 is sealed;

Fig. 6 is a structural schematic diagram of a guide plate provided with a sealing ring in Embodiment 1 of the present invention;

Fig. 7 is a schematic structural view of the guide plate provided with a sealing ring in Embodiment 2 of the present invention.

Detailed ways

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

Example 1

As shown in Figures 2 to 6, a sealing assembly structure of a rectangular fuel cell includes a flow guide plate or a bipolar plate, a membrane electrode, and a sealing ring, and the lower end of the sealing ring is glued 5 on the flow guide plate or In the sealing groove of the hydrogen-conducting anode surface 2 of the bipolar plate, the sealing ring is divided into two kinds of sealing areas, and one sealing area is arranged at the junction 7 of the membrane electrode inside the polar plate (as shown in Figure 2 and Figure 6). The top and bottom of the sealing ring are zigzag, and the inner side of the entire area is provided with a tongue-shaped opening that matches the membrane electrode. The membrane electrode can be provided with or without a frame. Slightly extended or the same length, so that the surroundings of the membrane electrode are tongue-shaped. 3 Insert into the tongue-shaped opening of the sealing ring. The other is set at the sealing groove 6 around the polar plate and the deflector, where the sealing ring is zigzag up and down, and there are no openings on the left and right, and the two bipolar plates are press-fitted and extruded to seal.

The sealing ring is made of elastic and stretchable material, the membrane electrode is inserted into the tongue-shaped opening at one end 3 of the sealing ring, the oxygen-conducting cathode surface 1 of the upper diversion plate or bipolar plate is connected to the lower diversion plate or bipolar plate The hydrogen-conducting anode surface 2 squeezes the sealing ring 4 and clamps the membrane electrode 3. The current-conducting plate or bipolar plate is repeatedly assembled into a battery stack, and the sealing effect is achieved after being compressed with a screw. The guide plate or bipolar plate is rectangular, and the membrane electrode is rectangular (as shown in FIG. 6 ).

The hydrogen-conducting anode surface sealing groove of the bipolar plate of the present invention uses a mold to cast a sealing ring to form a fixed structure. This structure cooperates with the three-in-one membrane electrode assembly to form a tongue shape up and down, and the sealing effect is achieved by pressing up and down. If there is any damage, It can be replaced freely to reduce losses, and the membrane electrode does not have a frame, which reduces costs and provides guarantee for mass production.

Example 2

As shown in Fig. 2 to Fig. 5 and Fig. 7, a sealing assembly structure of a square plate fuel cell includes a guide plate or a bipolar plate, a membrane electrode, and a sealing ring. It is characterized in that the lower end of the sealing ring Adhesive 5 is in the sealing groove of the hydrogen-conducting anode surface 2 of the diversion pole plate or the bipolar plate. 6), the sealing ring in this area is zigzag up and down, and there is a tongue-shaped opening matching the membrane electrode on the inner side of the entire area. The membrane electrode can be provided with or without a frame. The supporting material layer is slightly extended, so that the surroundings of the membrane electrode are tongue-shaped 3 and inserted into the tongue-shaped opening of the sealing ring. The other sealing area is set at 6 sealing grooves around each diversion hole of the pole plate, where the sealing ring is zigzag up and down, and there are no openings on the left and right, and the two bipolar plates are press-fitted and extruded to seal.

The sealing ring is made of elastic and stretchable material, the membrane electrode is inserted into the tongue-shaped opening at one end 3 of the sealing ring, the oxygen-conducting cathode surface 1 of the upper diversion plate or bipolar plate is connected to the lower diversion plate or bipolar plate The hydrogen-conducting anode surface 2 squeezes the sealing ring 4 and clamps the membrane electrode 3. The current-conducting plate or bipolar plate is repeatedly assembled into a battery stack, and the sealing effect is achieved after being compressed with a screw. The guide plate or bipolar plate is square, and the membrane electrode is octagonal (as shown in FIG. 7 ).

The hydrogen-conducting anode surface sealing groove of the bipolar plate of the present invention uses a mold to cast a sealing ring to form a fixed structure. This structure cooperates with the three-in-one membrane electrode assembly to form a tongue shape up and down, and the sealing effect is achieved by pressing up and down. If there is any damage, It can be replaced freely to reduce losses, and the membrane electrode does not have a frame, which reduces costs and provides guarantee for mass production.

The above-mentioned sealing assembly is suitable for various flow guide plates of fuel cells.

Claims (4)

1. kind of fuel cell seal assembly structure, comprise guide plate, membrane electrode, sealing ring, it is characterized in that, described sealing ring lower end is adhesive in the seal groove of leading the hydrogen anode surface of guide plate, the sealing circle is arranged on two kinds of zones, a kind of for being arranged on the inboard and membrane electrode junction of guide plate, sealing ring in this zone is indentation up and down, the inboard is provided with the ligule opening that is complementary with membrane electrode, membrane electrode inserts in this ligule opening, two guide plate pressing crush seal circles about during by integrated encapsulation make the ligule opening sting tight membrane electrode sealing; Another kind is arranged on each seal groove place, pod apertures edge of guide plate, and this place's sealing ring is indentation up and down, two guide plate pressing crush seal circle sealings up and down during by integrated encapsulation; Described membrane electrode is not established frame, and the area of middle proton exchange membrane has prolongation or equally long slightly than the porousness layer of support material in the membrane electrode, makes membrane electrode be ligule all around and inserts in the sealing ring ligule opening; Described membrane electrode can freely take out replacing.

2. kind of fuel cell seal assembly structure according to claim 1, it is characterized in that described sealing ring adopts the material with elastic extension, guide plate crush seal circle clamps membrane electrode up and down, this guide plate compresses the back sealing through repeating to be assembled into battery pile with screw rod.

3. kind of fuel cell seal assembly structure according to claim 1, it is characterized in that, described sealing ring comprises a sawtooth up and down at least, the part of this serrate projections and guide plate to lead the hydrogen anode surface bonding, adhering method is by the moulding of rubber mold disposal pouring.

4. kind of fuel cell seal assembly structure according to claim 1 is characterized in that, described sealing ring is indentation up and down, and this zigzag comprises circular arc, V-arrangement, rectangle.

Images