Preparation method of fuel cell composite board

Abstract

The invention discloses a preparation method of a fuel cell composite board, which comprises the following steps: weighing benzenediol, formaldehyde and deionized water in a three-neck flask, adding a transition metal compound as a catalyst, placing the three-neck flask in a water bath kettle, and heating to a stepped temperature; adding a predetermined mass of acetone, soaking for 1-3 days, replacing water, and drying to obtain an organic aerogel solid; placing the organic aerogel solid in a high-temperature tubular furnace, heating, keeping for 12-48 hours, cooling to obtain a carbon aerogel sample, and grinding the aerogel to obtain carbon aerogel powder; weighing the carbon aerogel powder and the resin powder, and placing the carbon aerogel powder and the resin powder in a molding press to obtain a molded bipolar plate, so as to obtain a carbon aerogel composite plate; the composite material has the advantages of high conductivity, high volume density, high mechanical property, high thermal stability and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cells, and in particular to the field of composite graphite bipolar plates for fuel cells. Background Art

[0002] The bipolar plate is one of the important components of the proton exchange membrane and plays a very important role in the long-term operation and function of the battery. The bipolar plate plays the role of hydrophobicity and providing channels for gas in the fuel cell, maintaining mechanical stability and conductive properties.

[0003] The existing bipolar plate preparation technologies are divided into three types: artificial graphite machining, metal plate stamping, and flexible graphite compression molding. Artificial graphite machined bipolar plates must be impregnated with plugging glue to plug leaks after machining because of the pores in artificial graphite. There is a risk of leakage in long-term use. The leakage rate is closely related to the bonding strength between the plugging glue and graphite. The machining time is long and the processing cost is high, which limits the cost of fuel cells and restricts the development of fuel cells. Metal plate stamping bipolar plates have low cost and can be processed in batches, but their materials are not resistant to electrochemical corrosion. At present, most of them use surface coating technology, but the coating process is not mature yet and cannot meet the market's growing requirements for fuel cell life and durability. It requires a breakthrough in basic materials to be fully applicable. Flexible graphite compression molded bipolar plates can be processed in batches, but their strength cannot meet the use requirements of fuel cells and can only meet the use of low-power bipolar plates. Summary of the invention

[0004] In view of this, it is necessary to overcome at least one of the above-mentioned defects in the prior art. The present invention provides a method for preparing a fuel cell composite plate, comprising: Step 1: weigh predetermined masses of hydroquinone, formaldehyde and deionized water into a three-necked flask, add a transition metal compound as a catalyst in a predetermined mass ratio, place the three-necked flask in a water bath, and heat it to a step temperature; Step 2: adding a predetermined mass of acetone into the three-necked flask and soaking for 1-3 days to displace water, and obtaining an organic aerogel solid after drying; Step 3: placing the organic aerogel solid in a high temperature tube furnace, heating it to 600-800° C., maintaining it for 12 to 48 hours under an inert gas atmosphere, cooling it down to obtain a carbon aerogel sample, and grinding the aerogel to obtain a carbon aerogel powder; optionally, 24 hours; Step 4: Weigh carbon aerogel powder and resin powder in a predetermined mass ratio and place them on both sides of the carbon paper, place them in a molding machine, and perform molding to obtain a molded bipolar plate; Step 5: The molded bipolar plate is impregnated and cured to obtain a carbon aerogel composite plate. The present invention aims at the drawback that the existing technologies all use existing solid materials for processing, and innovatively realizes the mixed preparation of raw materials; utilizes composite material technology to innovatively realize the mixing of carbon aerogel and resin from the processing of bipolar plates from single materials; and the present invention prepares the material of carbon aerogel and resin blend as the main body of the bipolar plate, uses carbon paper as the conductive skeleton, places the carbon aerogel and resin mixture on both sides of the carbon paper, and molds them in a molding machine to obtain the molded bipolar plate. The bipolar plate prepared by the present invention has the advantages of good conductivity, good volume density, good mechanical properties, good thermal stability, etc., and its conductivity is 400-600S / cm, bending strength is 85-110MPa, volume density is 1.45-1.67 g / cm3, and average thickness is 1.1-1.5mm; the present invention adopts carbon aerogel to form, which not only takes into account the functions of conductivity and support, but also has the advantages of easy forming, batch processing, and low cost. Carbon aerogel is a new type of carbon material with a cross-linked structure. It is porous, has good conductivity, large specific surface area, high porosity, and a wide range of pore size distribution. It is the only aerogel that conducts electricity. The sol-gel method for preparing carbon microspheres is simple to operate. It only needs to react in a solution. The raw materials are hydroquinone and formaldehyde, and the catalyst is a transition metal catalyst. After the reaction, gel is generated. The low surface tension of acetone is used to replace the water in the organic sol without destroying the structure of the organic gel. Then, the organic gel is converted into carbon aerogel by high-temperature carbonization and applied to bipolar plates. .

[0005] Furthermore, in step (1), the catechol is any combination of catechol, resorcinol and hydroquinone.

[0006] Furthermore, in step (1), the transition metal compound is any combination of ferrocene, ferric hydroxide, copper nitrate, magnesium nitrate, and magnesium hydroxide.

[0007] Furthermore, in step (1), the mass ratio of the hydroquinone to the formaldehyde to the deionized water is 1:(1-1.8):(10-20).

[0008] Furthermore, in step (2), the step temperatures of the water bath for immersion are 40°C, 60°C and 80°C, and the immersion time is 1-3 days.

[0009] Furthermore, in step (2), the mass of the acetone is 1-1.2 times the mass of the deionized water.

[0010] Furthermore, in step (4), the ratio of the carbon aerogel to the resin is (0.4-0.6): (0.6-0.4).

[0011] Furthermore, in step (4), the resin is any one of phenolic resin, epoxy resin and polymethyl methacrylate resin.

[0012] Furthermore, in step (4), the molding process is 5-50MPa, and the molding method is cold pressing.

[0013] Furthermore, in step (4), the impregnation resin is polyacrylic acid resin, and the curing temperature used is 150-200°C. Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which: Figure 1 is a performance data table of embodiments of the present invention and comparative examples; Figure 2 It is a conductivity bar graph of the embodiments of the present invention and the comparative example.

[0015] in, Figure 1 The following is a table of specific physical parameters of the embodiments and comparative examples. The bipolar plate formed by molding carbon aerogel and carbon paper has a moderate thickness, less than 1.5 mm, which reduces the mass of the bipolar plate. The addition of carbon paper improves the conductivity of the plate, making the plate conductivity > 400S / cm, and also improves the strength of the bipolar plate. Implementation

[0016] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0017] In the description of the present invention, it is necessary to understand that the terms "front", "rear", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0018] The preparation method of the fuel cell composite plate of the present invention will be described below with reference to the accompanying drawings, wherein Figure 1 is a performance data table of embodiments of the present invention and comparative examples; Figure 2 It is a conductivity bar graph of the embodiments of the present invention and the comparative example.

[0019] like Figure 1 As shown, an embodiment of the method for preparing a fuel cell composite plate according to the present invention comprises: Step 1: weigh predetermined masses of hydroquinone, formaldehyde and deionized water into a three-necked flask, add a transition metal compound as a catalyst in a predetermined mass ratio, place the three-necked flask in a water bath, and heat it to a step temperature; Step 2: adding a predetermined mass of acetone into the three-necked flask and soaking for 1-3 days to displace water, and obtaining an organic aerogel solid after drying; Step 3: placing the organic aerogel solid in a high-temperature tube furnace, heating it to 600-800° C., maintaining it for 12 to 48 hours under an inert gas atmosphere, cooling it down to obtain a carbon aerogel sample, and grinding the aerogel to obtain carbon aerogel powder.

[0020] Step 4: Weigh carbon aerogel powder and resin powder in a predetermined mass ratio and place them on both sides of the carbon paper, place them in a molding machine, and perform molding to obtain a molded bipolar plate. Step 5: The molded bipolar plate is impregnated and cured to obtain a carbon aerogel composite plate. According to some embodiments of the present invention, in step (1), the catechol is any combination of catechol, resorcinol and hydroquinone.

[0021] According to some embodiments of the present invention, in step (1), the transition metal compound is any combination of ferrocene, ferric hydroxide, copper nitrate, magnesium nitrate, and magnesium hydroxide.

[0022] According to some embodiments of the present invention, in step (1), the mass ratio of the hydroquinone to the formaldehyde to the deionized water is 1: (1-1.8): (10-20).

[0023] According to some embodiments of the present invention, in step (2), the step temperatures of the water bath for immersion are 40° C., 60° C. and 80° C., and the immersion time is 1-3 days.

[0024] According to some embodiments of the present invention, in step (2), the mass of the acetone is 1-1.2 times the mass of the deionized water.

[0025] According to some embodiments of the present invention, in step (4), the ratio of the carbon aerogel to the resin is (0.4-0.6): (0.6-0.4).

[0026] According to some embodiments of the present invention, in step (4), the resin is any one of phenolic resin, epoxy resin and polymethyl methacrylate resin.

[0027] According to some embodiments of the present invention, in step (4), the molding process is 5-50 MPa, and the molding method is cold pressing.

[0028] According to some embodiments of the present invention, in step (4), the impregnation resin is polyacrylic acid resin, and the curing temperature used is 150-200°C.

[0029] According to one embodiment of the present invention, Preparation of carbon aerogel Weigh 30 g of resorcinol into a beaker using an analytical balance.

[0030] Add 300 g of distilled water and 35 g of ferrocene into a beaker and stir for 30-50 min using magnetic stirring to achieve better mixing.

[0031] Use a 50 ml measuring cylinder to weigh 45 g of formaldehyde solution, add it to the beaker, and continue to stir magnetically until the solution is evenly mixed. Seal the beaker with plastic wrap and let it stand at room temperature for 24 hours.

[0032] The beaker was placed in a constant temperature water bath for 3 days, 40°C for one day and 80°C for two days, and reddish-brown hydrogel continued to flow out of the beaker.

[0033] During the drying process, 300 g of acetone was added to the beaker to fully replace the water in the gel to obtain the organic aerogel.

[0034] The organic aerogel was sent to a tubular furnace for calcination at 800°C under N2 protection for 24 hours, and then cooled to room temperature to obtain the desired carbon aerogel.

[0035] Preparation of composite panels (1) Weigh 25 g of carbon aerogel and 25 g of phenolic resin, and mix them by dry mixing to obtain a mixed material.

[0036] (2) Weigh 1 / 2 of the mixture and place it in a molding machine. Scrape it flat with a scraper and then attach carbon paper. Place the remaining 1 / 2 of the mixture on the other side of the carbon paper and scrape it flat with a scraper.

[0037] (3) The cold pressing method is adopted, and the molding is carried out at 5-45MPa in 9 stages.

[0038] (4) The molded bipolar plate was impregnated with polyacrylic acid for 24 hours, and then the impregnated bipolar plate was placed in a 150°C forced air oven for drying. The obtained composite bipolar plate was physically characterized in terms of thickness, conductivity, bending strength, etc.

[0039] Test method: (1) Thickness test: Take six different locations in the flow channel area of ​​the bipolar plate, use a thickness gauge to test the thickness, and record and calculate the average value.

[0040] (2) Conductivity test: The conductivity of the composite board was measured using an RTS-9 dual-electricity four-probe measuring instrument. In order to eliminate the contact resistance between the metal probe and the sample, the DC four-probe method was used to directly test the conductivity.

[0041] (3) Bending strength test: The WD-10D universal testing machine was used to measure the bending resistance of the composite board. The three-point bending method was used to test the bending strength of the composite board. The test steps are as follows: ① Make the sample into a long strip with a width of 10mm.

[0042] ② Adjust the support span so that the pressure head and support head are perpendicular to the specimen axis. ③ The indenter applies load evenly and without impact at a loading speed of 10 mm / s2 until the sample breaks, and reads the breaking load value.

[0043] Among them, the bending strength is calculated according to the following formula: δF=3PL / 2bh2 δF: flexural strength (MPa), P: breaking load value (N), L: support span (30mm), b: sample width (mm), h: sample thickness (mm).

[0044] According to some embodiments of the present invention, Preparation of carbon aerogel (1) Weigh 40 g of hydroquinone into a beaker using an analytical balance.

[0045] (2) Add 400 g of deionized water and 55 g of ferrocene into a beaker and stir for 40 min using a magnetic stirrer to ensure better mixing.

[0046] (3) Use a 100 ml measuring cylinder to weigh 50 g of formaldehyde solution and add it to a beaker. Continue to stir with a magnetic stirrer until the solution is evenly mixed. Cover the beaker with plastic wrap and let it stand at room temperature for 24 h.

[0047] (4) The beaker was placed in a constant temperature water bath for 3 days, 40°C for one day and 60°C for two days. Reddish-brown hydrogel continued to flow out of the beaker.

[0048] (5) During the drying process, 400 g of acetone was added to the beaker to fully replace the water in the gel to obtain an organic aerogel.

[0049] (6) The organic aerogel is calcined in a 600 °C tubular furnace under N2 protection for 24 h, then cooled to room temperature to obtain the desired carbon aerogel.

[0050] Preparation of composite panels (1) Weigh 30 g of carbon aerogel and 20 g of epoxy resin, and mix them by dry mixing to obtain a mixed material.

[0051] (2) Weigh 1 / 2 of the mixture and place it in a molding machine. Scrape it flat with a scraper and then attach carbon paper. Place the remaining 1 / 2 of the mixture on the other side of the carbon paper and scrape it flat with a scraper.

[0052] (3) The cold pressing method is adopted, and the molding is carried out at 5-45MPa in 9 stages.

[0053] (4) The molded bipolar plate was impregnated with polyacrylic acid for 24 hours, and then the impregnated bipolar plate was placed in a 180°C forced air oven for drying. The obtained composite bipolar plate was physically characterized in terms of thickness, conductivity, bending strength, etc.

[0054] According to some embodiments of the present invention, Preparation of carbon aerogel (1) Use an analytical balance to weigh 35 g of catechol into a beaker.

[0055] (2) Add 400 g of deionized water and 40 g of magnesium hydroxide into a beaker and stir for 50 minutes using a magnetic stirrer to achieve better mixing.

[0056] (3) Use a 100 ml measuring cylinder to weigh 50 g of formaldehyde solution and add it to a beaker. Continue to stir with a magnetic stirrer until the solution is evenly mixed. Cover the beaker with plastic wrap and let it stand at room temperature for 24 h.

[0057] (4) The beaker was placed in a constant temperature water bath for 3 days, 60°C for 2 days, and 80°C for 1 day. Reddish-brown hydrogel continued to flow out of the beaker.

[0058] (5) During the drying process, 500 g of acetone was added to the beaker to fully replace the water in the gel to obtain an organic aerogel.

[0059] (6) The organic aerogel is calcined in a tubular furnace at 800 °C under N2 protection for 24 h, then cooled to room temperature to obtain the desired carbon aerogel.

[0060] Preparation of composite panels (1) Weigh 20 g of carbon aerogel and 30 g of polyimide resin, and mix them by dry mixing to obtain a mixed material.

[0061] (2) Weigh 1 / 2 of the mixture and place it in a molding machine. Scrape it flat with a scraper and then attach carbon paper. Place the remaining 1 / 2 of the mixture on the other side of the carbon paper and scrape it flat with a scraper.

[0062] (3) The cold pressing method is adopted, and the molding is carried out at 5-45MPa in 9 stages.

[0063] (4) The molded bipolar plate was impregnated with polyacrylic acid for 24 hours, and then the impregnated bipolar plate was placed in a 200°C forced air oven for drying. The obtained composite bipolar plate was physically characterized in terms of thickness, conductivity, bending strength, etc.

[0064] A comparative example 1 of the present invention (1) Weigh 25 g of expanded graphite and 25 g of phenolic resin, and mix them by dry mixing to obtain a mixed material.

[0065] (2) Place the dry mixed material in a molding machine and use a scraper to flatten the material.

[0066] (3) The cold pressing method is adopted, and the molding is carried out at 5-45MPa in 9 stages.

[0067] (4) The molded bipolar plate was impregnated with polyacrylic acid for 24 hours, and then the impregnated bipolar plate was placed in a 150°C forced air oven for drying. The obtained composite bipolar plate was physically characterized in terms of thickness, conductivity, bending strength, etc. Any reference to "one embodiment," "an embodiment," "an illustrative embodiment," etc., means that a specific component, structure, or feature described in connection with the embodiment is included in at least one embodiment of the present invention. Such illustrative expressions throughout this specification do not necessarily refer to the same embodiment. Moreover, when a specific component, structure, or feature is described in connection with any embodiment, it is claimed that it is within the scope of those skilled in the art to implement such component, structure, or feature in connection with other embodiments.

[0068] Although specific embodiments of the present invention have been described in detail with reference to a number of illustrative embodiments of the present invention, it must be understood that a variety of other modifications and embodiments may be devised by those skilled in the art that will fall within the spirit and scope of the principles of the present invention. Specifically, within the scope of the foregoing disclosure, drawings, and claims, reasonable variations and improvements may be made in the arrangement of parts, modules, and / or their subordinate combination layouts without departing from the spirit of the present invention. Except for variations and improvements in parts, modules, and / or layouts, the scope thereof is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a fuel cell composite plate, the steps of which are as follows: Step 1: weigh predetermined masses of hydroquinone, formaldehyde and deionized water into a three-necked flask, add a transition metal compound as a catalyst in a predetermined mass ratio, place the three-necked flask in a water bath, and heat it to a step temperature; Step 2: adding a predetermined mass of acetone into the three-necked flask and soaking for 1-3 days to displace water, and obtaining an organic aerogel solid after drying; Step 3: placing the organic aerogel solid in a high-temperature tube furnace, heating it to 600-800° C., maintaining it for 12 to 48 hours under an inert gas atmosphere, cooling it down to obtain a carbon aerogel sample, and grinding the aerogel to obtain a carbon aerogel powder; Step 4: Weigh carbon aerogel powder and resin powder in a predetermined mass ratio and place them on both sides of the carbon paper, place them in a molding machine, and perform molding to obtain a molded bipolar plate; Step 5: The molded bipolar plate is impregnated and cured to obtain a carbon aerogel composite plate.

2. The method for preparing a fuel cell composite plate according to claim 1, It is characterized in that In step (1), the catechol is any combination of catechol, resorcinol and hydroquinone.

3. The method for preparing a fuel cell composite plate according to claim 1, It is characterized in that In step (1), the transition metal compound is any combination of ferrocene, ferric hydroxide, copper nitrate, magnesium nitrate and magnesium hydroxide.

4. The method for preparing a fuel cell composite plate according to claim 1, It is characterized in that In step (1), the mass ratio of the hydroquinone to the formaldehyde to the deionized water is 1:(1-1.8):(10-20).

5. The method for preparing a fuel cell composite plate according to claim 1, It is characterized in that In step (2), the step temperatures of the water bath for immersion are 40° C., 60° C. and 80° C., and the immersion time is 1-3 days.

6. The method for preparing a fuel cell composite plate according to claim 1, It is characterized in that In step (2), the mass of the acetone is 1-1.2 times the mass of the deionized water.

7. The method for preparing a fuel cell composite plate according to claim 1, It is characterized in that In step (4), the ratio of the carbon aerogel to the resin is (0.4-0.6): (0.6-0.4).

8. The method for preparing a fuel cell composite plate according to claim 1, It is characterized in that In step (4), the resin is any one of phenolic resin, epoxy resin and polymethyl methacrylate resin.

9. The method for preparing a fuel cell composite plate according to claim 1, It is characterized in that In step (4), the molding process is 5-50MPa, and the molding method is cold pressing.

10. The method for preparing a fuel cell composite plate according to claim 1, It is characterized in that In step (4), the impregnation resin is polyacrylic acid resin, and the curing temperature used is 150-200°C.

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