Fuel cell seal structure and method of making same

Abstract

The application provides a fuel cell sealing structure and a preparation method thereof, which comprises a carbon plate, a gasket, carbon paper, a CCM and a limiting element, a plurality of limiting holes are formed in the gasket, and the limiting element is arranged in any limiting hole; the carbon paper is arranged at the middle part of the gasket, the upper and lower sides of the CCM are both provided with the carbon paper and the gasket, any gasket is provided with the carbon plate away from the CCM, and any limiting element extends into the carbon plate. The method for sealing by using the soft rubber gasket has weak adhesion with the surface of the CCM, is beneficial to the flattening and positioning of the CCM, can not be limited by the thickness of the gasket, can control the compression amount of the carbon paper at will, and significantly improves the sealing property of the battery; by using the limiting element, the compression amount of the carbon paper can be limited during the fastening process, and the battery performance is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fuel cell, in particular to a fuel cell sealing structure and a preparation method thereof. BACKGROUND

[0002] Small area fuel cells used in laboratories are mainly used for some basic research tests, so the packaging and assembly method is relatively simple. Mainly reflected in: 1, CCM (proton membrane loaded with anode and cathode catalyst layer) is directly used for assembling the battery, and the carbon paper is not pre-assembled; 2, the CCM will not be pre-packaged frame, the flow field plate does not use sealing strip, and the gasket is placed during assembly for sealing and thickness limiting. The purpose of sealing is to ensure that the battery does not leak gas and runs in a reliable environment. The purpose of limiting thickness is to let the gasket play a supporting role in the tightening process of the battery tooling, preventing the carbon paper from being compressed too much and affecting the performance. This assembly method meets the requirements of high efficiency and convenience of battery assembly in basic scientific research, which is conducive to quickly accumulating scientific research data.

[0003] However, this method sacrifices the reliability of the battery to some extent. First of all, in order to achieve the purpose of limiting thickness, the elastic modulus of the gasket is large, and it is difficult to completely match the carbon plate or CCM after tightening, resulting in different degrees of gas leakage. With the continuous new requirements of actual application on the working condition of the stack, the problem of battery sealing in basic research is becoming more and more important. Secondly, due to the use of CCM for direct assembly, the wrinkles and deformation of the proton membrane will also introduce uneven factors, affecting the sealing. Thirdly, the gasket is purchased, and the user cannot control the thickness of the gasket, which is limited in the process of studying the compression amount of the carbon paper. SUMMARY

[0004] In view of the defects in the prior art, the purpose of the present application is to provide a fuel cell sealing structure and a preparation method thereof.

[0005] According to the fuel cell sealing structure provided by the present application, the carbon plate, the gasket, the carbon paper, the CCM and the limiting element are arranged, a plurality of limiting holes are formed in the gasket, and the limiting element is arranged in any limiting hole; the carbon paper is arranged at the middle part of the gasket, the carbon paper and the gasket are arranged on the upper and lower sides of the CCM, the carbon plate is arranged on the side away from the CCM of any gasket, and any limiting element extends into the carbon plate.

[0006] Preferably, the limiting element comprises a large cylinder and a small cylinder, the small cylinder extends into the carbon plate, the thickness of the large cylinder is d2, the thickness of the carbon paper is d1, and the thickness of the gasket is greater than d2 and less than d1.

[0007] Preferably, the gasket comprises a soft gasket with adhesive surface.

[0008] Preferably, the limiting hole has a diameter of no more than 40% of the gasket.

[0009] A method for preparing the fuel cell sealing structure is provided according to the present application, comprising the following steps:

[0010] In step S1, a preset compression thickness d2 is determined according to the electrical conductivity and mass transfer characteristics of the carbon paper.

[0011] In step S2, the insulating plate, the current collecting plate, and the carbon plate are sequentially placed on the fastener steel plate provided with the positioning hole.

[0012] In step S3, the limiting element with a large cylinder height of d2 is selected, and the small cylinder of the limiting element is inserted into the carbon plate of S2.

[0013] In step S4, the gasket with a thickness greater than d2 is selected.

[0014] In step S5, the selected gasket is placed on the carbon plate according to the positioning hole, and is pressed to realize pre-adhesion.

[0015] In step S6, the carbon paper is placed in the central area of the gasket.

[0016] In step S7, the CCM is placed on the carbon paper and the gasket according to the positioning hole, and the outer edge of the CCM is pressed to realize pre-adhesion.

[0017] In step S8, another gasket is placed on the CCM according to the positioning hole, and another piece of carbon paper is placed in the central area of the gasket.

[0018] In step S9, another carbon plate is selected to repeat step S3.

[0019] In step S10, the combined element of S9 is inverted and placed on the carbon paper and the gasket of S8 according to the positioning hole.

[0020] In step S11, the current collecting plate, the insulating plate, and the fastener steel plate are sequentially placed on the carbon plate of S9, and finally the CCM is used as the middle layer to form a symmetrical structure, and the whole structure is fastened by bolts to complete the battery assembly for testing.

[0021] Preferably, in step S2, the fastener steel plate comprises a rectangular stainless steel plate provided with positioning holes at four corners.

[0022] Preferably, in steps S6 and S8, the carbon paper is placed in a 5*5 area in the center of the gasket.

[0023] Preferably, in the step S4, the gasket exceeds d2 by a range between 5-20 μm.

[0024] Preferably, in the step S4, the selection and correction of the gasket comprises the following steps:

[0025] Step A1, place a gasket on the carbon plate, and place a plurality of wax blocks in the middle of the gasket;

[0026] Step A2, place another gasket, and place another carbon plate;

[0027] Step A3, apply a tightening force to the two carbon plates from the top and bottom directions by a torque wrench;

[0028] Step A4, measure the thickness of the compressed wax blocks, and obtain the compression thickness of the gasket;

[0029] Step A5, apply different torques, repeat steps A1-A4, and obtain the relationship between the torque and the compression thickness of the gasket;

[0030] Step A6, select an assembly torque according to the results of step A5, and ensure that the compression thickness corresponding to the torque is less than d2.

[0031] Preferably, in the step A1, the height of the wax blocks is greater than the height of the two gaskets stacked together.

[0032] Compared with the prior art, the present application has the following beneficial effects:

[0033] The present application uses a soft rubber gasket for sealing, the surface adhesion of which forms a weak adhesion with the CCM, which is beneficial to the flattening and positioning of the CCM, and can arbitrarily control the compression amount of the carbon paper without being limited by the thickness of the gasket, significantly improving the sealing performance of the battery; by using a limiting element, the compression amount of the carbon paper can be limited during tightening, ensuring the performance of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0034] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, made with reference to the accompanying drawings:

[0035] Figure 1 The present application mainly embodies the structure of a gasket;

[0036] Figure 2 The present application mainly embodies the schematic diagram of a gasket assembled with a limiting element;

[0037] Figure 3 The present application mainly embodies the cross-sectional view of the fuel cell sealing structure along the middle surface B; Figure 2 ​

[0038] Figure 4 This is a schematic diagram illustrating the height of the uncompressed carbon paper, the gasket, and the limiting element, which are the main features of this invention.

[0039] Figure 5 This invention mainly embodies step A1 of the gasket selection and calibration method;

[0040] Figure 6 Step A2 of this invention mainly embodies the method for selecting and calibrating gaskets;

[0041] Figure 7 Step A3 of this invention mainly embodies the method for selecting and calibrating gaskets;

[0042] Figure 8 This is a schematic diagram illustrating the present invention, which mainly embodies the existing common gasket.

[0043] Figure 9 This invention primarily embodies a cross-sectional view of a conventional gasket;

[0044] Figure 10 This is a schematic diagram illustrating the relationship between carbon paper compression and torque, which is the main feature of this invention.

[0045] Figure 11 This is a schematic diagram illustrating the sealing pressure drop of Comparative Examples 1-6 in this invention.

[0046] Figure 12 This is a schematic diagram illustrating the mass transfer performance of the carbon paper in Comparative Examples 1-6, which are the main components of this invention.

[0047] As shown in the figure:

[0048] Carbon plate 1, spacer 2, carbon paper 3

[0049] CCM4 Limit Element 5 Detailed Implementation

[0050] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0051] Example 1

[0052] like Figures 1-4As shown, a fuel cell sealing structure according to the present invention includes: a carbon plate 1, a gasket 2, carbon paper 3, a CCM 4, and a limiting element 5. The gasket 2 has multiple limiting holes, and a limiting element 5 is provided in any limiting hole. The carbon paper 3 is disposed in the middle of the gasket 2. Carbon paper 3 and gasket 2 are disposed on the upper and lower sides of the CCM 4. A carbon plate 1 is disposed on the side of any gasket 2 away from the CCM 4. Any limiting element 5 extends into the carbon plate 1.

[0053] The limiting element 5 includes a large cylinder and a small cylinder. The small cylinder extends into the carbon plate 1. The thickness of the large cylinder is d2, the thickness of the carbon paper 3 is d1, and the thickness of the gasket 2 is greater than d2 and less than d1. The height of the limiting element 5 is selected based on the thickness of the carbon paper 3 and the required compression amount to achieve the expected compression amount after assembly. The gasket 2 can be a soft rubber material with a low elastic modulus and a certain degree of surface stickiness. Since the gasket 2 is made of a soft material, its thickness only needs to be slightly thicker than d2; precise control is not required.

[0054] To prevent in-plane deformation of the gasket 2, the diameter of the limiting hole should not exceed 40% of the gasket 2, and a diameter of 5mm is preferred in practical applications.

[0055] Example 2

[0056] like Figures 1-4 As shown, a method for preparing the fuel cell sealing structure of Example 1 according to the present invention includes the following steps:

[0057] Step S1: Determine the preset compression thickness d2 based on the conductivity and mass transfer characteristics of carbon paper 3. The conductivity and mass transfer characteristics of carbon paper 3 may vary depending on the brand.

[0058] Step S2: On the fastener steel plate with positioning holes, place the insulating plate, current collector plate and carbon plate 1 in sequence according to the positioning holes;

[0059] Step S3: Select a limiting element 5 with a height of d2 for the large cylinder, and insert the small cylinder of the limiting element 5 into the carbon plate 1 of S2.

[0060] Step S4: Select a gasket 2 with a thickness exceeding d2. The tolerance for the thickness exceeding d2 of the gasket 2 is relatively high, and the range of the thickness exceeding d2 of the gasket 2 is between 5-20μm.

[0061] Step S5: Place the selected pad 2 on the carbon plate 1 according to the positioning hole, and press gently to achieve pre-adhesion;

[0062] Step S6: Place the carbon paper 3 in the 5*5 area in the center of the pad 2;

[0063] Step S7: Place CCM4 on carbon paper 3 and pad 2 according to the positioning hole, and gently press the outer edge of CCM4 to achieve pre-adhesion;

[0064] Step S8, take another gasket 2, according to the positioning hole on the CCM 4, and then place another piece of carbon paper 3 in the 5*5 area in the center of the gasket 2;

[0065] Step S9, take another carbon plate 1 and repeat step S3;

[0066] Step S10, according to the positioning hole, place the combined element of S9 upside down on the carbon paper 3 and gasket 2 of S8;

[0067] Step S11, place the current collector plate, insulating plate, and fastener steel plate in sequence on the carbon plate 1 of S9, finally form a symmetrical structure with CCM 4 as the middle layer, and use bolts to fasten the overall structure to complete the battery assembly for testing.

[0068] In step S2, the fastener steel plate includes a rectangular stainless steel plate with positioning holes at the four corners.

[0069] As shown in Figures 5-7 Step S4, the selection and correction of the gasket 2 includes the following steps:

[0070] Step A1, make gaskets 2 from alternative materials, place a gasket 2 on the carbon plate 1, and place multiple wax blocks in the middle of the gasket 2;

[0071] Step A2, place another gasket 2, and then place another carbon plate 1, without assembling carbon 3, limiting element 5, CCM 4, and assemble the battery tooling;

[0072] Step A3, apply a tightening force to the two carbon plates 1 from the top and bottom directions using a torque wrench;

[0073] Step A4, after tightening, obtain a certain thickness of the wax blocks, measure the thickness of the compressed wax blocks, and obtain the compression thickness of the gasket 2;

[0074] Step A5, apply different torques and repeat steps A1-A4 to obtain the relationship between torque and compression thickness of the gasket 2;

[0075] Step A6, select an assembly torque according to the results of step A5 to ensure that the corresponding compression thickness is less than d2.

[0076] In step A1, the height of the wax blocks is greater than the height of the two gaskets 2 stacked together.

[0077] After assembly, air tightness test and battery test are carried out. The air tightness test refers to filling high pressure in the battery, and observing the degree of pressure drop within 2 minutes after the air source is closed; the battery test refers to the AC impedance under 1600 mA / cm2. In the AC impedance, firstly, the HFR is observed to judge the conductivity of the carbon paper 3; secondly, the second impedance circle is observed to judge the mass transfer performance of the carbon paper 3. The smaller the HFR and the impedance circle are, the better.

[0078] As shown in Figure 8 and 9 , in the prior art, there is no limiting hole in the conventional gasket in the application, that is, the limiting element 5 in the application is not used. As shown in Figure 10 , in the application, the compression characteristics of three materials are obtained according to the selection and correction method of the gasket 2. Since it is planned to compress the carbon paper 3 to about 170 um, a larger torque of 5 Nm is selected to ensure that the gasket 2 is fully compressed. The conventional gasket is generally PTFE, which is relatively hard and not easy to compress, so the thickness of 170 um is directly selected.

[0079] As shown in Figure 11 and 12 , Comparative Examples 1-3 are soft rubber gaskets used in the application, and torques of 5 Nm, 5 Nm and 10 Nm are applied respectively. Comparative Examples 4 and 5 are conventional gaskets using PTFE, and torques of 5 Nm and 10 Nm are applied respectively. Comparative Example 6 is a soft rubber gasket without the limiting element 5 in the application, and a torque of 5 Nm is applied. As can be seen from Figure 8 , the use of soft rubber material can significantly improve the air tightness, because the weak adhesion of the soft rubber gasket can effectively fill the gap; by comparing Comparative Examples 2 and 3, it can be seen that as long as the soft rubber is effectively attached, sealing can be achieved, and the degree of freedom of assembly pressure is improved. As can be seen from Figure 9 , by comparing Comparative Examples 2 and 3 with Comparative Examples 4 and 5, under the action of the limiting element 5, the compression rate of the soft rubber gasket can be effectively controlled, so that the battery test performance of the carbon paper 3 is the same as that of the conventional frame; as can be seen from Comparative Example 6, without the limiting element 5, the carbon paper 3 will be excessively compressed, and the mass transfer impedance will increase.

[0080] The method for sealing by using a soft rubber gasket in the application has weak adhesion on the surface with the CCM 4, which is beneficial to the flattening and positioning of the CCM 4, and can not be limited by the thickness of the gasket 2, and the compression amount of the carbon paper 3 can be arbitrarily controlled, so that the sealing performance of the battery is significantly improved; by using the limiting element 5, the compression amount of the carbon paper 3 can be limited during the tightening process, so that the battery performance is guaranteed.

[0081] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0082] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the specific embodiments described above, and various changes or modifications can be made by those skilled in the art within the scope of the claims, which do not affect the essential content of the present application. The embodiments of the present application and the features in the embodiments can be arbitrarily combined with each other in the case of no conflict.

Claims

1. A fuel cell seal structure, characterized by, The utility model relates to a carbon plate (1), gasket (2), carbon paper (3), CCM (4) and limiting element (5), a plurality of limiting holes are seted up in gasket (2), limiting element (5) is provided in any limiting hole, The carbon paper (3) is arranged in the middle of the gasket (2), and the upper and lower sides of the CCM (4) are provided with the carbon paper (3) and the gasket (2), any gasket (2) is provided with the carbon plate (1) away from the CCM (4) side, any limiting element (5) extends into the carbon plate (1), The limiting element (5) includes a large cylinder and a small cylinder, the small cylinder extends into the carbon plate (1), the thickness of the large cylinder is d2, the thickness of the carbon paper (3) is d1, and the thickness of the gasket (2) is greater than d2 and less than d1. The gasket (2) includes a surface with sticky soft rubber gasket.

2. The fuel cell seal structure of claim 1, wherein The limiting hole diameter is not more than 40% of the gasket (2).

3. The fuel cell seal structure of claim 1, wherein The utility model relates to a carbon plate (1), gasket (2), carbon paper (3), CCM (4) and limiting element (5), a plurality of limiting holes are seted up in gasket (2), limiting element (5) is provided in any limiting hole, 4. A method of making a fuel cell seal structure as claimed in any one of claims 1 to 3, characterised in that, Step S1, according to the conductivity and mass transfer characteristics of the carbon paper (3), determine the preset compression thickness d2; Step S2, on the fastener steel plate provided with the positioning hole, according to the positioning hole, place the insulating plate, current collecting plate, carbon plate (1) in turn; Step S3, select the limiting element (5) with the height of the large cylinder as d2, insert the small cylinder of the limiting element (5) into the carbon plate (1) of S2; Step S4, select the gasket (2) with a thickness greater than d2; Step S5, place the selected gasket (2) on the carbon plate (1) according to the positioning hole, press, realize pre-adhesion; Step S6, place the carbon paper (3) in the center area of the gasket (2); Step S7, place the CCM (4) on the carbon paper (3) and the gasket (2) according to the positioning hole, press the outer edge of the CCM (4), realize pre-adhesion; Step S8, take another gasket (2), place it on the CCM (4) according to the positioning hole, and place another piece of carbon paper (3) in the center area of the gasket (2); Step S9, take another carbon plate (1) and repeat step S3; Step S10, according to the positioning hole, place the combined element of S9 on the carbon paper (3) and the gasket (2) of S8; Step S11, place the current collecting plate, insulating plate and fastener steel plate on the carbon plate (1) of S9 in turn, finally form a symmetrical structure with the CCM (4) as the middle layer, use bolts to fasten the overall structure, complete the battery assembly for testing. In step S2, the fastener steel plate includes a rectangular stainless steel plate, and positioning holes are formed in the four corners of the plate.

5. The method for producing a fuel cell seal structure according to claim 4, wherein In steps S6 and S8, the carbon paper (3) is placed in the 5*5 area of the center of the gasket (2).

6. The method for producing a fuel cell seal structure according to claim 4, wherein In step S4, the gasket (2) exceeds the range of d2 by 5-20 μm.

7. The method for producing a fuel cell seal structure according to claim 4, wherein In step S4, the selection and correction of the gasket (2) include the following steps:

8. The method for producing a fuel cell seal structure according to claim 4, wherein ​ Step A1, place one of the gaskets (2) on the carbon plate (1), and place several wax blocks in the middle of the gasket (2); Step A2, place another gasket (2), and place another carbon plate (1); Step A3, apply fastening force to the two carbon plates (1) from the top and bottom directions by a torque wrench; Step A4, measure the thickness of the compressed wax blocks, which is the compressed thickness of the gasket (2); Step A5, apply different torques, repeat steps A1-A4, and obtain the relationship between torque and the compressed thickness of the gasket (2); Step A6, select an assembly torque according to the results of step A5, and ensure that the corresponding compressed thickness is less than d2.

9. The method for producing a fuel cell seal structure according to claim 8, wherein In step A1, the height of the wax blocks is greater than the height of the two gaskets (2) stacked together.

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