CN103881123B - A kind of PBI/H used for high-temperature fuel cell3PO4The preparation method of doping - Google Patents

Abstract

A kind of PBI/H used for high-temperature fuel cell₃PO₄The preparation method of doping, including the pretreatment of PBI film, PBI film leaching phosphoric acid, it is dried, and repeats above-mentioned leaching phosphoric acid and dry run to ensure in PBI film that phosphorus acid content reaches the 500% of film quality, and ensure the concordance of film that different batches processes.This method has that technical process is the most controlled, is prone to batch production；In film, phosphorus acid content concordance is high, uniformity is strong；And long-time place phosphoric acid not easily run off, the advantage such as stable content, when using phosphate-doped PBI film prepared by this method as dielectric film used for high-temperature fuel cell, there is the advantages such as electrical conductivity is high, cell discharge performance is good.

Description

A preparation method of PBI/H3PO4 doped film for high temperature fuel cell

technical field

The invention relates to a preparation method of a PBI/H ₃ PO ₄ doped film for a high-temperature fuel cell.

Background technique

Proton exchange membrane fuel cell (PEMFC) is an electrochemical conversion device that directly converts the chemical energy of fuel into electrical energy. It has the advantages of high energy conversion efficiency, no pollution, no noise, and long service life. Power and other fields have broad application prospects.

Proton exchange membrane is the core component of PEMFC. At present, most people use perfluorinated sulfonic acid membrane represented by Nafion membrane for the development and research of fuel cells. However, the high proton conductivity of this type of membrane depends on the presence of water, so its service temperature is usually 100 °C lower. The low temperature operating conditions make fuel cells face many problems in practical applications, such as catalyst CO poisoning, difficult hydrothermal management of the system, and low recovery of heat energy. This will make the application of PEMFC in power supply, facing practical problems such as fuel reformation and purification, difficulty in heat dissipation, complex structure and low overall energy efficiency. In order to increase the operating temperature of PEMFC to above 100℃, it is an important development direction to develop high-temperature PEMFC technology.

At present, when phosphoric acid doped polymer membranes such as polybenzimidazole (PBI) are used, great attention has been paid to the proton conductivity of phosphoric acid even in the anhydrous state. PBI is a class of aromatic heterocyclic compounds with excellent chemical and thermal stability; after being doped with inorganic acid, as a solid proton conductor, the fuel cell can operate at a temperature of up to 200 ° C, and can be used at normal pressure and without humidification operate under the conditions.

PBI can be synthesized by condensation polymerization. In all PBI polymers, the -N group on each benzimidazole repeating unit can combine with the acid in the form of hydrogen bond, which is expected to show better proton conductivity. The PBI membrane used in high-temperature fuel cells is treated with impregnated phosphoric acid to improve its electrical conductivity, because the content of phosphoric acid in the PBI membrane after impregnated with phosphoric acid is as high as 500wt.%. Therefore, the concentration of phosphoric acid varies greatly during the dipping process, which will inevitably affect the uniformity and consistency of phosphoric acid in the PBI film, and ultimately affect the uniformity of phosphoric acid in the PBI/H ₃ PO ₄ doped film and the different batches of PBI/H ₃ PO ₄ doped films. Consistency of heteromembrane.

Patent 200710190632.9 discloses a method for preparing a phosphoric acid-doped polybenzimidazole membrane using a polybenzimidazole-phosphoric acid-water ternary system. In this method, firstly, the PBI-phosphoric acid mixture is prepared and placed on a glass plate Obtain a PBI-phosphoric acid doped film, and then immerse the obtained film in 20-60wt.% phosphoric acid to obtain a PBI-phosphoric acid doped film with high phosphoric acid content. In the preparation process of this method, the process of placing the mixed solution on a glass plate may cause uneven film thickness and thus lead to

The content of phosphoric acid in the medium is uneven and the consistency of different batches of membranes is not high, which is not suitable for mass production and commercial application.

Contents of the invention

The present invention aims at the shortcomings of poor uniformity of H ₃ PO ₄ in the PBI film in the process of preparing PBI/H ₃ PO ₄ doped film in the prior art, and poor consistency of H ₃ PO ₄ content in films prepared in different batches. Phosphoric acid doping of PBI film by impregnation method improves the uniformity of PBI/H ₃ PO ₄ doped film H ₃ PO ₄ and the consistency between batches of films, and at the same time increases the content of phosphoric acid in the doped film And then improved the ionic conductivity of this film, the concrete scheme of the present invention is as follows:

A kind of preparation method of PBI/H ₃ PO ₄ doping film for high temperature fuel cell, comprises the following steps,

1) Pretreatment of PBI membrane: place the cut PBI membrane in a container filled with deionized water, and place the container in a water bath at 50-100°C for 1-12 hours, then take out the PBI membrane in Dry in an oven at 80-180°C for 0.5-2 hours;

2) Weighing of PBI film: mark, weigh and record the PBI film obtained in step 1) one by one;

3) Pickling treatment of PBI film: put the PBI film obtained in the weighing step 2) into a container, and inject phosphoric acid solution into the container, and ensure that the phosphoric acid solution is immersed in all PBI films, and place the container Heat treatment at 80-160°C for 1-96 hours in an oil bath to obtain PBI/H ₃ PO ₄ primary doped film;

4) Drying treatment of PBI/H ₃ PO ₄ primary doped film: put the PBI/H ₃ PO ₄ primary doped film obtained in step 3) into a vacuum oven and dry at 80-180°C for 0.5-5 hours to obtain Dried PBI/H ₃ PO ₄ primary doped film;

5) Weighing of PBI/H ₃ PO ₄ primary doped film: weigh the dried PBI/H ₃ PO ₄ primary doped film obtained in step 4) at room temperature, and record;

6) Calculation of phosphoric acid content: use the following formula to calculate the phosphoric acid content in the PBI film, the percentage of phosphoric acid content = (PBI film mass after pickling - PBI film mass before pickling) / PBI film mass before pickling;

7) Preparation of PBI/H ₃ PO ₄ doped film: If the phosphoric acid content in the PBI film calculated by the calculation method described in step 6) is greater than or equal to the preset value X, the preparation of the PBI/H ₃ PO ₄ doped film is completed;

If the phosphoric acid content in the PBI film is less than the preset value X, repeat the above steps 3)-6) in sequence until the phosphoric acid content in the PBI film is greater than or equal to the preset value X, and a PBI/H ₃ PO ₄ doped film is obtained.

The concentration of the phosphoric acid solution is 65wt.%-98wt.%.

The area of the PBI membrane immersed in the phosphoric acid solution per liter in the step 3) is 100-2000 cm ² .

The dipping conditions are that the temperature of the oil bath is 80-160° C., and the treatment time is 1-48 hours;

Described better dipping condition is that oil bath temperature is 100～150 ℃, and treatment time is better for 12～72 hours;

The best impregnation conditions are that the temperature of the oil bath is 110-130° C., and the treatment time is 24-48 hours.

After soaking in phosphoric acid, the PBI film must be dried in a vacuum oven. The drying temperature is preferably 100-150°C, most preferably 110-130°C.

Phosphoric acid content percentage = (PBI film quality after pickling - PBI film quality before pickling) / PBI film quality before pickling, the preset value X of phosphoric acid content in the obtained film is 100~650%, 300~600% is better, 450 ~550% is best.

High temperature fuel cell membranes for impregnated phosphoric acid are various types of PBI membranes, including AB-PBI, mPBI, F6-PBI, OO-PBI, OSO2-PBI, Py-PBI, Py-O-PBI, SO2-PBI or One or more of SPBI.

Description of drawings

Fig. 1 draws the uniformity curve of phosphoric acid content in single treatment and multiple drying treatment PBI film by comparative example 1 and the data obtained in embodiment 4; 10 samples were weighed to calculate the phosphoric acid content in the film after dipping, and the curve was drawn. It can be seen from the figure that the phosphoric acid content of the membrane treated by single-word immersion fluctuates greatly, and the phosphoric acid content of the membrane treated by multiple immersion and drying fluctuates less, and the uniformity of the same batch is better.

Fig. 2 is the change of phosphoric acid content for placing 6 days by single drawing of the data obtained in Comparative Example 2 and Example 5; The phosphoric acid content in the membrane was tested every 24 hours. The curve in the figure shows that after a long period of storage, the content of phosphoric acid in the PBI membrane treated by single immersion decreases significantly with the prolongation of storage time, while the content of phosphoric acid in the PBI membrane after multiple immersion and drying treatments decreases slowly after being placed for a long time.

Figure 3 is the performance curve of the PBI film assembled battery obtained in Comparative Example 1 and Example 4; wherein the phosphoric acid content in the PBI film is 550%, the battery test temperature is 180 ° C, hydrogen at normal pressure, flow rate 50SCCM; oxygen at normal pressure, flow rate 100 SCCM. The test device is an Arbin electronic load.

detailed description

The present invention is described in detail below through examples, but the present invention is not limited to the examples.

Example 1:

Cut 4 pieces of ab-PBI membrane 10×10cm ² , place the cut PBI membrane in a large beaker, wash it with deionized water, then put the PBI membrane into a beaker filled with high-purity water, and put it in a water bath at 50-100 degrees Celsius Treated for 12 hours. Put the PBI film evenly into the air oven for drying treatment. 120 degrees Celsius, 2 hours. Weigh, record. Slowly pour 85% phosphoric acid into 4 beakers filled with PBI membranes respectively, and the phosphoric acid is completely submerged in the PBI membranes. Put them into 4 oil pans for heat treatment, and the oil temperatures are 90, 100, 110, and 120 degrees Celsius respectively. Take it out at 2, 6, 12, and 24 hours, vacuum dry and weigh it, and calculate the phosphoric acid content at 90, 100, 110, and 120 degrees Celsius for 2 hours. The phosphoric acid content in the PBI film is 108%, 116%, respectively. , 121%, 317%; when the temperature was 90, 100, 110, and 120 degrees Celsius for 6 hours, the phosphoric acid content in the PBI film was: 128%, 134%, 149%, 398%, and the temperature for 12 hours was 90, 100, 110 Phosphoric acid contents in PBI film at 120 degrees Celsius are: 120%, 196%, 253%, 445% 342%, 536%.

Example 2:

Cut 3 pieces of ab-PBI membrane 10×10cm ² , put the cut PBI membrane in a large beaker, wash it with deionized water, then put the PBI membrane into a beaker filled with high-purity water, and put it in a water bath at 50-100 degrees Celsius Treated for 12 hours. Put the PBI film evenly into the air oven for drying treatment. 120 degrees Celsius, 2 hours. Weigh, record. Slowly inject 65%, 85%, and 98% phosphoric acid into three beakers filled with PBI membranes, and the phosphoric acid is completely submerged in the PBI membranes. Put them into 3 oil pans for heat treatment respectively, and the oil temperature is 120 degrees Celsius. 65% and 85% phosphoric acid were treated for 30 hours, and 98% phosphoric acid was treated for half an hour. After the treatment, they were taken out and vacuum-dried and weighed. The calculated phosphoric acid content in the PBI film treated with 65% phosphoric acid for 30 hours is 376%; the calculated phosphoric acid content in the PBI film treated with 85% phosphoric acid for 30 hours is 542%; the calculated phosphoric acid content in the PBI film treated with 98% phosphoric acid for 30 hours is 556% .

Example 3:

Cut 15 pieces of ab-PBI membrane 6× ^10cm2 , place the cut PBI membrane in a large beaker, wash it with deionized water, then put the PBI membrane into a beaker filled with high-purity water, and put it in a water bath at 50-100 degrees Celsius Treated for 12 hours. Put the PBI film evenly into the air oven for drying treatment. 120 degrees Celsius, 2 hours. Weigh, record. Slowly inject 85% phosphoric acid into the beaker containing the PBI membrane, submerging all the PBI membrane. Put it into an oil pan for heat treatment, and the oil temperature is 120 degrees Celsius. At 5, 7.5, 12.5, 17, and 36 hours, take out the marked 6 samples to be tested, vacuum dry and weigh them, and calculate the phosphoric acid content. The average phosphoric acid content of 6 samples after 5 hours drying is 383%; the average phosphoric acid content after 7.5 hours drying is 401%; the average phosphoric acid content after 12.5 hours drying is 424%; the average phosphoric acid content after 17 hours drying is 504%; 36 hours drying The average phosphoric acid content is 576%.

Example 4:

Cut 15 pieces of ab-PBI membrane 6× ^10cm2 , and mark 10 of them, put the cut PBI membrane in a large beaker, wash it with deionized water, then put the PBI membrane into a beaker filled with high-purity water, Put it into a 50-100 degree Celsius water bath for 12 hours. Put the PBI film evenly into the air oven for drying treatment. 120 degrees Celsius, 2 hours. Weigh, record. Slowly inject 85% phosphoric acid into the beaker containing the PBI membrane, submerging all the PBI membrane. Put it into an oil pan for heat treatment, and the oil temperature is 120 degrees Celsius. Dried and impregnated every 7 hours, 5 consecutive treatments for a total of 35 hours of impregnation. Finally, after drying, take out the marked 10 samples to be tested, and the calculated phosphoric acid content is 587%, 601%, 576%, 590%, 568%, 559%, 573%, 585%, 564%, 571%.

Example 5:

In order to prove the stability of the phosphoric acid content in the membrane after the PBI membrane was impregnated with phosphoric acid, the PBI membrane was impregnated and dried for 5 times and then impregnated and dried for a total of 36 hours. One time, continuous test for 144 hours, the phosphoric acid content in the film was 576%, 556%, 556%, 555%, 544%, 545% with the prolongation of placement.

Embodiment 6:

Cut 15 pieces of ab-PBI membrane 6× ^10cm2 , and mark 5 of them, put the cut PBI membrane in a large beaker, wash it with deionized water, then put the PBI membrane into a beaker filled with high-purity water, Put it into a 50-100 degree Celsius water bath for 12 hours. Put the PBI film evenly into the air oven for drying treatment. 120 degrees Celsius, 2 hours. Weigh, record. Slowly inject 85% phosphoric acid into the beaker containing the PBI membrane, submerging all the PBI membrane. Put it into an oil pan for heat treatment, and the oil temperature is 120 degrees Celsius. Dried and impregnated every 8 hours, 6 consecutive treatments for a total of 48 hours of impregnation, 5 batches in total. Finally, after drying, take out the marked 5 samples to be tested, and calculate the phosphoric acid content. The average phosphoric acid content of the five batches was 580%, 573%, 563%, 565%, and 572%, respectively.

Embodiment 7:

Cut 1 piece of m-PBI membrane 10×10cm ² , put the cut PBI membrane in a large beaker, wash it with deionized water, then put the PBI membrane into a beaker filled with high-purity water, and put it in a water bath at 50-100 degrees Celsius Treated for 12 hours. Put the PBI film evenly into the air oven for drying treatment. 120 degrees Celsius, 2 hours. Weigh, record. Slowly inject 85% phosphoric acid into the beaker containing the PBI membrane, submerging all the PBI membrane. Put it into an oil pan for heat treatment, and the oil temperature is 120 degrees Celsius. Treat for 30 hours, vacuum dry and weigh at 120°C every 5 hours, and calculate the phosphoric acid content to be 600%.

Comparative example 1:

Cut 15 pieces of ab-PBI membrane 10× ^10cm2 and mark 10 of them, put the cut PBI membrane in a large beaker, wash it with deionized water, then put the PBI membrane into a beaker filled with high-purity water, put Put it into a 50-100 degree Celsius water bath for 12 hours. Put the PBI film evenly into the air oven for drying treatment. 120 degrees Celsius, 2 hours. Weigh, record. Slowly inject 85% phosphoric acid into the beaker containing the PBI membrane, submerging all the PBI membrane. Heat it in a frying pan. The oil temperature is 120 degrees Celsius, and it is processed for 36 hours. Blot the phosphoric acid on the surface of the treated PBI membrane with filter paper, weigh and calculate the phosphoric acid content of 10 marked pieces: 522%, 578%, 582%, 513%, 571%, 553%, 546% , 553%, 569%, 531%.

Comparative example 2:

In order to prove the stability of the phosphoric acid content in the membrane after the PBI membrane is soaked in phosphoric acid, the PBI membrane treated after soaking in phosphoric acid for 36 hours is tested for the change of phosphoric acid content after standing for a period of time, and the test is performed every 24 hours for 144 hours. , the content of phosphoric acid in the extended film with the placement is respectively: 556%, 494%, 504%, 508%, 512%, 504%.

Table 1 shows the content of phosphoric acid in the PBI film at different temperatures and different immersion times obtained in Example 1; the PBI film was immersed in 85% phosphoric acid solution, and the temperature of the oil bath was set to 90, 100, 110, and 120°C respectively. When the soaking time is 2, 6, 12, and 24 hours under each temperature condition, take it out, dry it and weigh it, and calculate the phosphoric acid content in the film. The data in the table shows that with the increase of immersion temperature and the extension of time, the phosphoric acid content in the PBI membrane increases, and the phosphoric acid content increases significantly when immersing at 120 °C.

Table 1

Table 2 shows the effect of the phosphoric acid concentration obtained in Example 2 on the phosphoric acid content in the PBI film; the PBI film was immersed in 98, 85, and 65% phosphoric acid solutions respectively, the temperature of the oil bath was 120°C, and the immersion time was 0.5, 30 , Take it out after 30 hours, dry it and weigh it, and calculate the phosphoric acid content in the film. The data indicated that the phosphoric acid concentration increased, the time required for impregnating the same concentration of phosphoric acid in the PBI membrane decreased, and the phosphoric acid content of the PBI membrane impregnated with low concentration of phosphoric acid was lower at the same immersion time.

Table 2

Film number phosphoric acid concentration heating temperature heating time Phosphoric acid percentage A 98% 120°C 0.5h 556 B 85% 120°C 30h 542 C 65% 120°C 30h 376

Table 3 shows the phosphoric acid content of the same batch of dry-treated PBI membranes obtained in Example 3; 5 samples were taken from the PBI membranes of the same batch, and when they were dried and weighed each time, the phosphoric acid content of the calculator and the batch average value were obtained. . The data in the table shows that the same batch of immersion and drying treatment, as the immersion time increases, the phosphoric acid content in the PBI membrane gradually increases, and the phosphoric acid content in the membrane exceeds 550% after 36 hours.

table 3

Table 4 is the content of phosphoric acid in PBI membranes processed by different batches obtained in Example 6; under the condition of 5 batches of 120 degrees Celsius, 5 samples were taken from the PBI membranes of 85% phosphoric acid multiple times of drying treatment, weighed and calculated multiple times Phosphoric acid content in the film after immersion, and calculate the average value. The data in the table shows that the average value of phosphoric acid content in each batch of PBI membranes treated by different batches is relatively uniform.

Table 4

Film number 1 2 3 4 5 A 581 572 553 563 578 B 606 578 583 571 582 C 556 582 554 553 563 D. 593 563 569 583 571 E. 565 571 558 553 564 average 580 573 563 565 572

Claims (9)

1. a PBI/H used for high-temperature fuel cell₃PO₄The preparation method of doping, it is characterised in that: comprise the following steps,

1) pretreatment of PBI film: the PBI film cut out is placed in the container filling deionized water, and described container is placed in 50-100 DEG C of water-bath process 1-12 hour after, take out PBI film dried 0.5-2 hour in 80-180 DEG C of baking oven；

2) the weighing of PBI film: by step 1) gained PBI film labelling piecewise, weigh, record；

3) pickling of PBI film processes: will be through the step 2 weighed) the PBI film of gained inserts in container, and in described container, inject phosphoric acid solution, and ensure phosphoric acid solution submergence all PBI film, described container is placed in oil bath pan heat treatment 1-96 hour at 80-160 DEG C, obtains PBI/H₃PO₄Doping；

4)PBI/H₃PO₄The dried of doping: by step 3) gained PBI/H₃PO₄Doping is inserted in vacuum drying oven and is dried 0.5-5 hour under the conditions of 80-180 DEG C, obtains dried PBI/H₃PO₄Doping；

5)PBI/H₃PO₄Weighing of doping: by step 4) the dried PBI/H of gained₃PO₄One time doping is weighed at room temperature, record；

6) calculating of phosphorus acid content: use equation below to calculate the phosphorus acid content in PBI film, PBI film quality before phosphorus acid content percentage ratio=(PBI film quality before PBI film quality-pickling after pickling)/pickling；

7)PBI/H₃PO₄The preparation of doping: according to step 6) in described computational methods calculated PBI film phosphorus acid content more than or equal to preset value X, PBI/H₃PO₄Prepared by doping, preset value X is 450～550%；

If phosphorus acid content is less than preset value X in PBI film, it is repeated in above-mentioned steps 3)-6), to phosphorus acid content in PBI film more than or equal to preset value X, obtain PBI/H₃PO₄Doping.

2. PBI/H as claimed in claim 1₃PO₄The preparation method of doping, it is characterised in that: the concentration of described phosphoric acid solution is 65wt.%-98wt.%.

3. PBI/H as claimed in claim 1₃PO₄The preparation method of doping, it is characterised in that: described step 3) in every liter of phosphoric acid solution the area of the PBI film of dipping be 100-2000cm²。

4. PBI/H as claimed in claim 1₃PO₄The preparation method of doping, it is characterised in that: immersion condition be oil bath temperature be 80～160 DEG C, the process time is 1～48 hour.

5. PBI/H as claimed in claim 4₃PO₄The preparation method of doping, it is characterised in that: preferably immersion condition is: oil bath temperature is 100～150 DEG C, processes time 12～72 hours.

6. PBI/H as claimed in claim 5₃PO₄The preparation method of doping, it is characterised in that: best immersion condition is: oil bath temperature is 110～130 DEG C, processes time 24～48 hours.

7. PBI/H as claimed in claim 1₃PO₄The preparation method of doping, it is characterised in that: must dry in vacuum drying oven after PBI film leaching phosphoric acid, described drying temperature preferably 100～150 DEG C.

8. PBI/H as claimed in claim 7₃PO₄The preparation method of doping, it is characterised in that: described drying temperature is preferably 110～130 DEG C.

9. PBI/H as claimed in claim 1₃PO₄The preparation method of doping, it is characterized in that: the high-temperature fuel cell film for impregnation of phosphoric acid is various types of PBI films, including one or two or more kinds in AB-PBI, mPBI, F6-PBI, OO-PBI, OSO2-PBI, Py-PBI, Py-O-PBI, SO2-PBI or SPBI.