CN111342076A

CN111342076A - Processing method of sealing line

Info

Publication number: CN111342076A
Application number: CN201811551068.3A
Authority: CN
Inventors: 孙海; 赵世雄; 孙公权
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2018-12-18
Filing date: 2018-12-18
Publication date: 2020-06-26

Abstract

The invention provides a method for processing a seal line of a bipolar plate and a membrane electrode of a fuel cell, which comprises the steps of injecting liquid sealant into a seal groove of the bipolar plate through a through injection hole in a glue injection mode, flowing in the seal groove and filling the seal groove with the sealant, and then heating to enable the sealant to be formed between the bipolar plate and a mould in a cross-linking mode to form the seal line. The invention realizes the integrated molding of the sealing gasket and the bipolar plate, and the method can ensure that the sealing surface of the sealing line, namely the contact surface of the arc top and the second polar plate is smooth, and the sealing is ensured; meanwhile, the glue injection holes are filled with the sealant, so that the gas barrier property is not influenced. Meanwhile, the automatic injection molding is applied to the batch production of integrated bipolar plates and membrane electrodes with sealing elements, the production efficiency is high, the sealing performance is good, the dimensional accuracy of the sealing line is high, and the labor cost is saved.

Description

Processing method of sealing line

Technical Field

The invention relates to a method for processing a seal line of a bipolar plate or a membrane electrode of a fuel cell, belonging to the field of fuel cells.

Background

The bipolar plate of the fuel cell has huge use amount, and because graphite is the main material, the material cost is lower, and the mass production process of the bipolar plate of the fuel cell forms the main cost of the bipolar plate of the fuel cell. The main functions of the bipolar plate include isolating cathode and anode reaction raw materials, conducting electricity, mass transfer, heat transfer and force transfer. Wherein the function of isolating the anode and cathode materials is mainly realized by a sealing piece on the bipolar plate. The existing sealing gasket and sealing line have the problem of difficult batch and rapid production. At present, no automatic equipment capable of realizing quick fixation of a sealing gasket on a bipolar plate exists, manual placement is required, and the process step becomes the bottleneck of batch production, the bottleneck of safety and the bottleneck of product reliability.

Traditional sealed mode no matter use sealed pad or seal line, all have and need the manual work to put, the not high, the low problem of reliability of production efficiency. The manner of using a dispenser is limited by the rubber material, poor flowability and the use of thermosetting resins. For example, the commonly used perfluoroether resin with temperature resistance and chemical corrosion resistance is a very good sealing material, but no perfluoroether resin which can be cured at normal temperature and normal pressure is developed at present, so that an automatic continuous production process for the material is difficult to develop.

Disclosure of Invention

At present, the selection of materials of the fuel cell technology under the high-temperature and high-acidity environment is greatly limited, and particularly, the sealing materials, such as traditional silicon rubber, natural rubber, nitrile rubber and the like, can not meet the use requirement of the fuel cell when the fuel cell is in contact with a high-acidity medium at a high temperature of more than 140 ℃. Fluororubber or ethylene propylene diene monomer rubber has the characteristics of acid resistance, temperature resistance and the like, but the processing performance of the fluororubber or the ethylene propylene diene monomer rubber is inferior to that of materials with high fluidity before curing, such as silicon rubber, natural rubber and the like. The technological means of the mature silicon rubber such as dispensing, room temperature cross-linking injection molding and the like are difficult to be directly used on the fluororubber and the ethylene propylene diene monomer.

Based on the defects of the prior art, the invention reduces the flowing distance of glue solution by manufacturing the through holes on the bipolar plate or the membrane electrode seal edge and injecting glue from the back surface of the bipolar plate or the membrane electrode seal edge provided with the sealing gasket so as to adapt to the low-fluidity characteristic of the sealing rubber, and realizes the integrated molding of the sealing line on the bipolar plate of the fuel cell by injection molding, hot pressing and curing.

The invention provides a processing method of a seal line of a bipolar plate, wherein the two surfaces of the bipolar plate are A, B surfaces respectively; the A surface of the bipolar plate is provided with a sealing groove; a die matched with the seal groove and the bipolar plate integrally is arranged above the bipolar plate mechanism in a matched manner; the sealing groove is provided with a plurality of through holes as through injection holes, the through injection holes penetrate through the surface A and the surface B, the processing method is that liquid or viscoelastic state sealant with fluidity is injected through one end of the through injection holes positioned on the surface of the bipolar plate B in an injection mode, the injected sealant flows into the sealing groove on the surface of the bipolar plate A through the through injection holes, flows in the sealing groove and is filled with the sealing groove, then the sealing groove is heated, the sealant is formed by cross-linking and cross-linking between the bipolar plate and a mould, the sealing line is formed, and a certain amount of sealant is injected into the through injection holes for sealing the through injection holes.

The invention also provides a processing method of the seal line of the membrane electrode, when the membrane electrode is a fuel cell membrane electrode with a seal frame, the membrane electrode comprises a cathode and an anode which are correspondingly superposed on both sides of an electrolyte membrane, the part of the electrolyte membrane without the cathode and the anode is provided with the seal frame, both surfaces of the membrane electrode are A, B surfaces respectively, the surface A is provided with the seal frame, the seal frame is provided with a seal groove, a mould which is matched with the seal groove and the membrane electrode is arranged above the membrane electrode in a matching way, the seal groove is provided with a plurality of through holes as through holes, the through holes penetrate through the surface A and the surface B, the processing method is to inject the fluid sealant into one end of the membrane electrode B surface through the through holes, the injected sealant flows into the seal groove of the surface A of the membrane electrode through the through holes, and flowing and filling the sealing groove in the sealing groove, then heating, and injecting a certain amount of sealant into the through injection hole for sealing the through injection hole after the sealing line is formed.

Based on the technical scheme, preferably, the sealant is one of fluororubber and ethylene propylene diene monomer.

Based on above technical scheme, it is preferred, the quantity that the notes hole set up is related to the mobility of sealed glue and bipolar plate's length, and sealed glue's mobility is stronger, and the notes hole that runs through can set up some less relatively, and sealed glue's mobility is weak, sets up the more hole that runs through relatively, and bipolar plate is longer, and the through notes hole quantity that sets up is more.

Based on the technical scheme, the temperature of the heating treatment is preferably 25-340 ℃.

Based on the technical scheme, preferably, the width of the sealing groove is 0.5-10 mm; the height of the sealing groove is 0.05-5 mm.

Based on the technical scheme, preferably, the width of the sealing line is 0.5-10 mm; the height of the sealing wire groove is 0.05-5 mm.

Based on the technical scheme, the bipolar plate is preferably a graphite bipolar plate, a metal and graphite composite bipolar plate, and a graphite and polymer composite bipolar plate.

Advantageous effects

The invention realizes the integrated molding of the sealing gasket and the bipolar plate or the MEA, and the method can ensure that the sealing surface of the sealing line, namely the contact surface of the arc top and the second polar plate is smooth, and the sealing is ensured; meanwhile, the through holes are filled with the sealant, so that the gas barrier property of the bipolar plate or the membrane electrode is not influenced. Meanwhile, the automatic injection molding is applied to the bipolar plate with the sealing element which is integrated in batch production, the production efficiency is high, the sealing performance is good, the size precision of the sealing line is high, and the labor cost is saved.

Drawings

FIG. 1 is a view of a sealing wire slot;

FIG. 2 is a through-hole view;

FIG. 3 is a cross-sectional view of a sealant line;

FIG. 4 is a seal view;

FIG. 5 is a through-the-note drawing of the present invention;

FIG. 6 is a through mold injection diagram of comparative example 2;

wherein 1: a bipolar plate; 2: a seal line; FIG. 3: a through injection hole; 3': a through injection hole; 4: and (5) molding.

Detailed Description

Example 1

The method of the invention is that a sealing slot is constructed on one side of a first graphite plate bipolar plate (figure 1), a matched mould is arranged above one side of the bipolar plate with a sealing slot, a through injection hole is arranged on the other side of the bipolar plate (figure 2), and a sealing glue is injected into the sealing slot through the through injection hole by adopting an injection molding method (figure 5) to form a sealing line, thereby replacing the traditional sealing form of using an O-shaped ring.

The section of the sealing glue line is a sealing line section diagram (figure 3) formed by injection, the arc part is used as a sealing side to be contacted with a wire groove of a second graphite polar plate, the sealing is realized by the elastic contact of the arc top of the sealing line and the second polar plate, the graphite bipolar plate contacted with the sealing line can be provided with the sealing wire groove (figure 4a) or not (figure 4b), whether the second bipolar plate is provided with the sealing wire groove depends on the height difference between the sealing line of the first graphite bipolar plate and the first bipolar plate, the technical personnel in the field can adjust the sealing glue line by themselves, and the sealing between the two bipolar plates is ensured.

Example 2

The method comprises the steps of constructing a sealing line (figure 1) on one side of an MEA (membrane electrode assembly) edge sealing, placing a matched mold above one side of the MEA edge sealing, arranging a through injection hole (figure 2) on the other side of the MEA edge sealing, and injecting sealant into the surface of the MEA edge sealing through the through injection hole (figure 5) by adopting an injection molding method to form the sealing line instead of the traditional sealing form of an O-shaped ring formed by placing or dispensing.

The section of the sealing rubber line is a sealing line section diagram formed by injection (figure 3), the arc-shaped part is used as a sealing side to be in contact with the line groove of the second graphite polar plate, sealing is realized by the elastic contact of the arc top of the sealing line and the second polar plate, and the sealing edge of the MEA in contact with the sealing line can be provided with the sealing line groove (figure 4a) or not (figure 4 b).

Comparative example 1

The method of the invention is that a sealing slot (figure 1) is constructed on one side of a first graphite plate bipolar plate, a matched mould is arranged above one side of the bipolar plate with a sealing slot, a through injection hole such as 3' (figure 2) is arranged on the other side of the bipolar plate, the through injection hole is not positioned under the sealing slot and is not vertically communicated with the sealing slot, and a sealing glue is injected into the sealing slot (figure 5) through the through injection hole by adopting an injection molding method to form a sealing line, thereby replacing the traditional sealing form of using an O-shaped ring.

The section of the sealing rubber line is a sealing line section diagram formed by injection (figure 3), the arc-shaped part is used as a sealing side to be contacted with a wire groove of a second graphite polar plate, sealing is realized by the elastic contact of the arc top of the sealing line and the second polar plate, a graphite bipolar plate contacted with the sealing line can be provided with the sealing wire groove (figure 4a) or not (figure 4b), holes are formed at the positions outside the sealing line, the sealing line is sensitive to the pressure difference of two sides of the sealing structure, and the sealing failure can be caused by the overlarge pressure difference.

Comparative example 2

The method comprises the steps of constructing a sealing slot (figure 1) on one side of a first graphite plate bipolar plate, placing a matched mould above one side of the bipolar plate with a sealing groove, wherein the mould is provided with a through hole as a through injection hole (figure 6) for injecting a sealant into the sealing groove, injecting a liquid sealant into the sealing groove through the through injection hole, flowing in the sealing groove and filling the sealing groove with the sealant, then heating to enable the sealant to be cross-linked and molded between the bipolar plate and the mould to form the sealing line, and according to the focusing method, the section of the injection hole of the sealing glue line is as shown in figure 6, and after focusing is finished, the circular arc part has the residue of the injection hole.

Claims

1. A processing method of seal line of bipolar plate is characterized in that the two surfaces of the bipolar plate are A, B surfaces respectively; the A surface of the bipolar plate is provided with a sealing groove; a die matched with the sealing groove and the bipolar plate integrally is arranged above the bipolar plate in a matched manner; the processing method comprises the steps of injecting liquid sealant into one end of the bipolar plate B surface through the through injection hole in a glue injection mode, enabling the injected sealant to flow into the sealing groove of the bipolar plate A surface through the through injection hole, enabling the injected sealant to flow into the sealing groove of the bipolar plate A surface and fill the sealing groove, and then conducting heating treatment to enable the sealant to be formed between the sealing groove of the bipolar plate and a mold in a cross-linking mode to form the sealing line.

2. A processing method of a seal line of a membrane electrode is characterized in that: the two sides of the membrane electrode are A, B surfaces respectively, the membrane electrode is attached with a sealing frame, a sealing groove is arranged on the sealing frame, a mold matched with the sealing groove and the whole membrane electrode is arranged above the membrane electrode in a matched mode, the sealing groove is provided with a plurality of through holes as through injection holes, the through injection holes penetrate through the surface A and the surface B, the processing method is that the sealant with fluidity is injected through one end of the through injection holes on the surface B of the membrane electrode in a glue injection mode, the injected sealant flows into the sealing groove on the surface A of the membrane electrode through the through injection holes, flows in the sealing groove and is filled with the sealing groove, and then the sealing groove is heated to enable the sealant to be formed between the sealing groove of the bipolar plate and the mold in a cross.

3. The process of claim 1 or 2, wherein the sealant is one of a fluoro-elastomer and an ethylene propylene diene monomer.

4. The process according to claim 1 or 2, characterized in that the temperature of the heat treatment is between 25 and 340 ℃.

5. The machining method according to claim 1 or 2, wherein the width of the seal groove is 0.5-10 mm; the height of the sealing groove is 0.05-5 mm.

6. The process according to claim 1 or 2, characterized in that the width of the sealing line is between 0.5 and 10 mm; the height of the sealing wire groove is 0.05-5 mm.

7. The process of claim 1 wherein said bipolar plates are graphite bipolar plates, metal and graphite composite bipolar plates, graphite and polymer composite bipolar plates.