CN1385915A - Composite type proteon exchange film for high-temp. direct methanol fue cell and preparation process thereof - Google Patents

Abstract

The present invention relates to electrochemical fuel cell technology, in particular to a high-temperature direct methanol fuel cell proton exchange membrane and a preparation method of the membrane. The composite proton exchange membrane for high-temperature direct methanol fuel cell of the present invention uses commercially available polyvinylidene fluoride or polyvinyl alcohol as raw material, and adds nano-ceramic powder mixed with inorganic polybasic acid. Composite proton exchange membrane with nano-microporous structure prepared by slurry method, calendering method or dipping method. The proton exchange membrane prepared by the invention has a nano-microporous structure, the methanol permeability in the temperature range of 80-180 DEG C is smaller than that of the Nafion membrane, and the alcohol resistance performance is good. The preparation process of the proton exchange membrane prepared by the present invention is simple, the cost of the membrane is lower than that of the Nafion membrane, the industrialization is easy, and it can be used as the proton exchange membrane of the direct methanol fuel cell which can also operate normally at high temperature (above 100°C).

Description

Composite proton exchange membrane for high temperature direct methanol fuel cell and preparation method thereof

technical field

The invention relates to an electrochemical fuel cell technology, more specifically a proton exchange membrane for a high-temperature direct methanol fuel cell, and also relates to a preparation method for the membrane.

Background technique

In today's world, fuel vehicle exhaust emissions have become one of the main sources of environmental pollution. The development of electric vehicles powered by electric energy is an effective means to reduce the exhaust emissions of fuel vehicles and reduce the degree of environmental pollution. The fuel cell with the characteristics of "zero emission" is the most promising new energy source to replace the existing fuel engine as the power source of automobiles. Among various types of fuel cells, in addition to other general advantages of fuel cells, direct methanol fuel cells (DMFC) also have the advantages of abundant and easy-to-obtain fuel sources, cheap prices, easy transportation and storage, simple battery structure, volume and It has the advantages of small weight (about 1/3 of hydrogen-oxygen fuel cell) and low cost (about 1/2 of hydrogen-oxygen fuel cell). Therefore, the direct methanol fuel cell (DMFC) system is the most suitable mobile power source for electric vehicles or other portable devices. Since the catalytic oxidation reaction of fuel methanol used in the fuel cell system is very slow at temperatures below 100° C., the overall performance of the system is affected. Therefore, high temperature (above 100°C) direct methanol fuel cells have become a new trend in the development of fuel cells. However, the existing Nafion membrane used in direct methanol fuel cells not only has the problem of high price, but also has poor proton conductivity at high temperature, high permeability of methanol to the membrane, and these two shortcomings also decrease with the increase of temperature. Problems such as increase, are not suitable for use in high-temperature direct methanol fuel cells. Therefore, how to improve the high-temperature proton conduction rate of the proton exchange membrane, reduce its methanol permeability at high temperature, and develop a new type of proton exchange membrane with high performance and low cost is a major technical problem in the development of high-temperature direct methanol fuel cells. Researchers are currently focusing their research on this type of fuel cell on the proton exchange membrane.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, to provide a high-temperature proton conductivity and good alcohol resistance, and the price is lower than the price of the commercially available Nafion membrane, which can be applied in high-temperature direct methanol fuel cells Composite proton exchange membrane.

The invention also provides a preparation method of the composite proton exchange membrane for the high-temperature direct methanol fuel cell.

The composite proton exchange membrane for high-temperature direct methanol fuel cell of the present invention uses commercially available polyvinylidene fluoride or polyvinyl alcohol as raw material, and adds nano-ceramic powder mixed with inorganic polybasic acid. Composite proton exchange membrane with nano-microporous structure prepared by slurry method, calendering method or dipping method;

The inorganic polybasic acid refers to a compound with the general formula A ₃ BM ₁₂ O ₄₀ ·nH ₂ O having an anionic cluster of [BM ₁₂ O ₄₀ ] _n structure (Keggin structure), wherein A=H, B=Si, P , M=Mo, W; the inorganic polybasic acid is selected from silicotungstic acid, phosphomolybdic acid, phosphotungstic acid or silicomolybdic acid, etc.;

The nano-ceramic powder refers to a ceramic compound mixed with inorganic polybasic acid, wherein the nano-inorganic ceramic powder is selected from silica, zirconia or silicon dioxide powder, and the particle size is ≤30nm.

Concrete preparation process of the present invention is as follows:

(1) Add 5% to 50% of the weight of the nano-ceramic powder in the nano-ceramic powder without

Organic polybasic acid, mix well and set aside;

(2) Take 100 parts by weight of polyvinylidene fluoride or polyvinyl alcohol and 15 to 70 parts by weight of

The nano-ceramic powder of organic polybasic acid is mixed evenly and prepared;

(3) dissolving polyvinylidene fluoride or polyvinyl alcohol in a conventional solvent to prepare a polymer solution, and

Add nano-ceramic powder mixed with inorganic polybasic acid to the polymer solution, vibrate evenly

Swing for 5 to 30 minutes, the conventional solvent is selected from N-methylpyrrolidone, acetone or

water;

(4) Spread the mixed solution on the surface of the glass petri dish by casting hot pressing method, at room temperature ~

Heating at 90°C for 10-40 minutes, then drying at room temperature for 0.5-20 hours, the solvent

The film formed after drying is torn off from the surface of the petri dish, and hot-pressed at 100-170°C for 3-

It takes 20 minutes; or the film can be prepared by slurrying method, calendering method or dipping method.

Compared with existing materials and technologies, the present invention has the following advantages:

1. The compound type proton exchange compound with nano-microporous structure made by the preparation method proposed by the present invention

The exchange membrane has excellent proton conduction performance at high temperature, and its proton conduction rate is greater than that of Nafion membrane.

sub-conductivity.

2. The proton exchange membrane prepared by the present invention has a nano-microporous structure, and the temperature range is 80-180°C

The methanol permeability is smaller than that of Nafion membrane, and the alcohol resistance performance is good. Take sample 1 as an example, see Table 1 for details.

3. the present invention prepares the preparation technology of proton exchange membrane simple, and membrane cost is lower than Nafion membrane, is easy to produce

Industrialization will promote the development of high-temperature direct methanol fuel cells.

Detailed ways

Example 1

Dope phosphotungstic acid equivalent to 30% of the weight of the silicon dioxide powder into the silicon dioxide powder with a particle size of 7.5nm, and mix evenly. Weigh 100 parts by weight of polyvinylidene fluoride and 60 parts by weight of silicon dioxide doped with phosphotungstic acid, dissolve polyvinylidene fluoride in N-methylpyrrolidone to form a polymer solution, and add 30% phosphotungsten Acidic silicon dioxide, vibrate evenly with ultrasonic waves for 20 minutes; spread the mixed solution on the surface of a petri dish, heat at 80°C for 20 minutes, dry at room temperature for 15 hours to form a film, and finally press the film at 160°C Just 10 minutes, and the prepared film is sample 1. Soak the membrane in deionized water at 80°C for 3 hours before use. The comparison of high temperature methanol permeation between sample 1 and Nafion membrane is shown in Table 1.

Example 2

Add silicotungstic acid equivalent to 45% of the weight of the silicon dioxide powder into the silicon dioxide powder with a particle size of 7.5nm, and mix evenly. Weigh 100 parts by weight of polyvinylidene fluoride and 60 parts by weight of silicon dioxide doped with phosphotungstic acid, dissolve polyvinylidene fluoride in N-methylpyrrolidone to form a polymer solution, add 45% tungsten phospho Acidic silicon dioxide, vibrated by ultrasonic waves for 20 minutes; spread the mixed solution on the surface of a petri dish, heat at 90°C for 5 minutes, dry at room temperature for 15 hours to form a film, and finally press the film at 160°C for 10 minutes That's it. Soak the membrane in deionized water at 80°C for 3 hours before use.

Example 3

Add phosphotungstic acid equivalent to 30% of the weight of the silica powder into the silica powder with a particle size of 12nm, and mix evenly. Weigh 100 parts by weight of polyvinylidene fluoride and 70 parts by weight of silica powder mixed with phosphotungstic acid, dissolve polyvinylidene fluoride in N-methylpyrrolidone to form a polymer solution, and add 30% phosphotungsten Acidic silica, vibrate evenly with ultrasonic wave for 10 minutes; spread the mixed solution on the surface of the petri dish, heat at 25°C for 40 minutes, dry at room temperature for 24 hours to form a film, and finally press the film at 170°C for 3 minutes. Soak the membrane in deionized water at 80°C for 3 hours before use.

Example 4

Add silicotungstic acid equivalent to 50% of the weight of the zirconia powder into the zirconia powder with a particle size of 12nm, and mix evenly. Weigh 100 parts by weight of polyvinylidene fluoride and 15 parts by weight of zirconia powder mixed with silicotungstic acid, dissolve polyvinylidene fluoride in acetone to form a polymer solution, and add zirconia containing 50% silicotungstic acid to it Powder, oscillate with ultrasound for 30 minutes; spread the mixed solution on the surface of a petri dish, heat at 90°C for 5 minutes, dry at room temperature for 1 hour to form a film, and finally press the film at 100°C for 20 minutes. Soak the membrane in deionized water at 80°C for 3 hours before use.

Example 5

Add phosphotungstic acid equivalent to 5% of the weight of the silica powder into the silica powder with a particle size of 12nm, and mix evenly. Weigh 100 parts by weight of polyvinylidene fluoride and 40 parts by weight of silica powder mixed with phosphotungstic acid, dissolve polyvinylidene fluoride in N-methylpyrrolidone to form a polymer solution, and add 1% phosphotungsten Acidic silica powder, oscillated by ultrasound for 1 minute; spread the mixed solution on the surface of a petri dish, heat at 70°C for 20 minutes, dry at room temperature for 0.5 hour to form a film, and finally heat press the film at 160°C for 10 minutes. Soak the membrane in deionized water at 80°C for 3 hours before use.

Example 6

Add phosphotungstic acid equivalent to 45% of the weight of the silica powder into the silica powder with a particle size of 7.5nm, and mix evenly. Weigh 100 parts by weight of polyvinylidene fluoride and 70 parts by weight of silica powder mixed with phosphotungstic acid, dissolve polyvinylidene fluoride in acetone to form a polymer solution, and add silica containing 45% phosphotungstic acid Powder, oscillate with ultrasound for 30 minutes; spread the mixed solution on the surface of a petri dish, heat at 60°C for 10 minutes, dry at room temperature for 20 hours to form a film, and finally press the film at 100°C for 20 minutes. Soak the membrane in deionized water at 80°C for 3 hours before use.

Example 7

Add phosphotungstic acid equivalent to 30% of the weight of the zirconia powder into the zirconia powder with a particle size of 12nm, and mix evenly. Weigh 100 parts by weight of polyvinylidene fluoride and 70 parts by weight of zirconia powder mixed with phosphotungstic acid, dissolve polyvinylidene fluoride in acetone to form a polymer solution, and add zirconia containing 30% phosphotungstic acid Powder, oscillate with ultrasound for 30 minutes; spread the mixed solution on the surface of a petri dish, heat at 50°C for 40 minutes, dry at room temperature for 20 hours to form a film, and finally heat-press the film at 170°C for 5 minutes. Soak the membrane in deionized water at 80°C for 3 hours before use.

Example 8

Add phosphotungstic acid equivalent to 30% of the weight of the zirconia powder into the zirconia powder with a particle size of 12nm, and mix evenly. Weigh 100 parts by weight of polyvinyl alcohol and 70 parts by weight of zirconia powder mixed with phosphotungstic acid and mix evenly. Using the calendering method, heat and knead the adhesive high-pressure polyethylene in a calender until it is completely plasticized, and then add Softener rubber, after uniform mixing, add a small amount of lubricant and the above-mentioned mixed materials, repeatedly knead, pull the film, cover both sides of the film with nylon mesh, and press it with a hydraulic press, and form a film after cooling.

Example 9

Add silicotungstic acid equivalent to 45% of the weight of the silicon dioxide powder into the silicon dioxide powder with a particle size of 7.5nm, and mix evenly. Weigh 100 parts by weight of polyvinyl alcohol and 60 parts by weight of silicon dioxide mixed with phosphotungstic acid, use the slurry method, heat and dissolve polyvinyl alcohol in water, add silicon dioxide containing 45% phosphotungstic acid, Ultrasonic vibration for 1 minute, prepare a slurry, pour it on a steel plate covered with glass cloth in advance, push the film liquid with a glass rod, cover the polyester film, squeeze out the residual liquid with a pressure roller, press it on the steel plate, heat and keep it warm, and finally cool to After peeling off the polyester membrane at room temperature, the required composite proton exchange membrane can be obtained.

Example 10

Add phosphotungstic acid equivalent to 45% of the weight of the silica powder into the silica powder with a particle size of 7.5nm, and mix evenly. Weigh 100 parts by weight of polyvinyl alcohol and 70 parts by weight of silica powder mixed with phosphotungstic acid, heat and dissolve polyvinyl alcohol in water by dipping method, add silica powder containing 45% phosphotungstic acid to it, Vibrate ultrasonically for 30 minutes, mix it into a slurry, after defoaming, apply it on the vinylon mesh, and form a film after air drying.

The comparison of the high-temperature methanol permeability of the proton exchange membrane of the present invention and the Nafion membrane of table 1 Temperature T(°C) Methanol concentration (mol/L) Methanol permeability (S ^-1 cm ² ×10 ^-6 ) sample 1 Nafion117 80 1.0 1.2 4.4 110 1.0 2.0 7.9 130 1.0 2.4 9.1 160 1.0 3.7 13.3

Claims (4)

1. A method for preparing a composite proton exchange membrane for a high-temperature direct methanol fuel cell, characterized in that its proportioning and process conditions are as follows: (1) adding an inorganic polybasic acid equivalent to 5% to 50% of the weight of the nano-ceramic powder in the nano-ceramic powder, and mixing it uniformly for use; (2) Get 100 parts by weight of polyvinylidene fluoride or polyvinyl alcohol and 15 to 70 parts by weight of nano-ceramic powder mixed with inorganic polybasic acid, mix and prepare materials; (3) Dissolve polyvinylidene fluoride or polyvinyl alcohol in a conventional solvent to prepare a polymer solution, and add nano-ceramic powder mixed with an inorganic polybasic acid to the polymer solution, and shake it uniformly for 5 to 30 minutes. The solvent is selected from N-methylpyrrolidone, acetone or water; (4) Spread the mixed solution on the surface of the glass culture dish by casting hot pressing method, heat at room temperature to 90°C for 10 to 40 minutes, and then dry at room temperature for 0.5 to 20 hours; The surface of the dish is torn off, and hot-pressed at 100-170° C. for 3-20 minutes; or prepared into a film by slurrying, calendering or dipping. 2. a kind of high-temperature direct methanol fuel cell composite proton exchange membrane preparation method according to claim 1, is characterized in that: Inorganic polybasic acid refers to the compound whose general formula is A ₃ BM ₁₂ O ₄ 0·nH ₂ O and the anion cluster is [BM ₁₂ O ₄₀ ] _n structure (Keggin structure), where A=H, B=Si, P, M =Mo, W; Inorganic polybasic acid is selected from silicotungstic acid, phosphomolybdic acid, phosphotungstic acid or silicomolybdic acid, etc.; The nano-ceramic powder is selected from silica, zirconia or silicon dioxide powder, and the particle size is less than or equal to 30nm. 3. a kind of high temperature direct methanol fuel cell composite proton exchange membrane preparation method according to claim 1, is characterized in that: (1) Add phosphotungstic acid equivalent to 25-35% of the weight of silicon dioxide powder or silicotungstic acid equivalent to 40-50% of the weight of silicon dioxide powder to the silicon dioxide powder with a particle size of 5-20nm, and mix Uniform and ready for use; (2) Get 100 parts by weight of polyvinylidene fluoride or polyvinyl alcohol and 30 to 60 parts by weight of silicon dioxide powder mixed with phosphotungstic acid or silicotungstic acid and mix them evenly to prepare materials; (3) Dissolve polyvinylidene fluoride or polyvinyl alcohol in a conventional solvent to prepare a polymer solution, and add silicon dioxide powder mixed with phosphotungstic acid or silicotungstic acid to the polymer solution, and oscillate evenly for 30 Minutes, wherein the conventional solvent is selected from N-methylpyrrolidone, acetone or water; (4) Spread the mixed solution on the surface of the glass petri dish, heat it at 40-80°C for 10-30 minutes, and then dry it at room temperature for 2-15 hours; tear off the film formed after the solvent is dried from the surface of the petri dish, and heat it at 130°C- Hot press at 170°C for 5 to 15 minutes, or prepare a film by slurrying, calendering or dipping. 4. The composite proton exchange membrane for high-temperature direct methanol fuel cells prepared by the preparation method according to claims 1-3.