CN101414686A - Compound film and application thereof for high-temperature fuel battery with proton exchange film - Google Patents

Abstract

The invention relates to a composite membrane for a high-temperature proton exchange membrane fuel cell, in particular to an organic and inorganic composite film and the application thereof to a high-temperature proton exchange membrane fuel cell. The composite membrane is composed of proton exchange membrane resin and inorganic adding materials, wherein the inorganic adding materials are modified montmorillonites, and the content of the modified montmorillonites in the membrane is from 2 to 10 wt%. The sulfoacid polyarylether sulphone (ketone)-class proton exchange resin adopted by the invention has high thermomechanical stability and thermochemical stability; the inorganic adding materials are sulfoacid organic sulfoacid montmorillonites with good hydrophilicity and certain proton conduction capability. The organic and inorganic composite membrane has the characteristics of low cost, stable structure and good high-temperature proton conduction performance, and can be used for a high-temperature proton exchange membrane fuel cell.

Description

A kind of composite membrane and its application in high temperature proton exchange membrane fuel cell

technical field

The invention relates to a composite membrane for a high-temperature proton exchange membrane fuel cell, specifically an organic-inorganic composite membrane and its application in a high-temperature proton exchange membrane fuel cell, and is an organic membrane with good high-temperature proton conductivity. —Inorganic composite proton exchange membrane and its application.

Background technique

In the working process of proton exchange membrane fuel cell (PEMFC), the proton exchange membrane plays the role of conducting protons and blocking fuel and oxidant. In order to improve the working efficiency of PEMFC, the proton exchange membrane is required to have high proton conductivity and low fuel penetration. At the same time, since the operating PEMFC is an oxidation/reduction atmosphere, it has a certain temperature, active oxide and electrode potential, which requires the proton exchange membrane to have good thermal/mechanical and chemical stability to ensure the PEMFC. Stable operation. Especially in recent years, with the extensive development and application of PEMFC technology, in order to further improve battery efficiency, enhance catalyst anti-CO ability, simplify hydrothermal management system, etc., the demand for high-temperature PEMFC is constantly increasing. With the increase of PEMFC working temperature, higher and more urgent requirements are put forward for the key material, proton exchange membrane, and it is more closely dependent on the research and development of high temperature resistant proton exchange membrane. Therefore, high temperature resistant proton exchange membrane It has become a new research hotspot in the field of PEMFC key material technology.

The existing perfluorosulfonic acid proton exchange membrane has excellent chemical stability and proton conductivity, but its glass transition temperature (Tg) is 120-130 °C, and there are mechanical problems when it is used in high-temperature PEMFC (~150 °C). unstable factor. More importantly, the proton conduction of this proton exchange membrane depends on the presence of water. When the battery temperature is higher than 100 ° C, the proton conduction capacity of the membrane will decrease due to the loss of water in the membrane, resulting in the failure of PEMFC to operate. At present, the research work on high-temperature-resistant proton exchange membranes is mainly aimed at maintaining a certain proton conductivity under low humidity by reducing the dehydration rate of the membrane when the working temperature is below 150°C. In order to solve the problem of thermal stability of membrane materials, people use high temperature resistant polymers - aromatic polymers containing ether sulfone (ketone) bonds or heterocycles, such as polyaryl ketone, polyaryl sulfone, polyimide, polybenzo Imidazole, etc., they have good thermomechanical stability, and their Tg is above 180°C. In order to solve the problem of the decrease of membrane conductivity caused by high temperature dehydration, Watanabe et al [J. Electrochem. Add noble metal catalysts and/or hydrophilic oxides, the catalysts can catalyze the chemical reaction of hydrogen and oxygen permeated into the membrane to generate water to humidify the membrane, hydrophilic oxides can absorb water under high humidity conditions, and absorb water at low humidity Under certain conditions, water is released to achieve the purpose of humidifying the membrane.

Montmorillonite (MMT) is a monoclinic layered aluminosilicate, due to its large aspect ratio and specific surface area, unique layered one-dimensional nanostructure and programmable reactivity between layers, it makes It has become the most commonly used layered silicate for the preparation of polymer nanocomposites.

In the literature [Journal of Power Sources, 2003, 118: 205-211; Solid State Ionics, 2006, 177: 1137-1144; Electrochimica Acta, 2005, 50: 2639-2645; J.Electrochem.Soc.153: A2239-A2244 ], people use MMT to improve the methanol barrier performance of Nafion membrane, because the addition of MMT increases the bypass channel of fuel permeation in the membrane, thereby reducing the methanol permeation rate of the membrane. Literature [Solid State Ionics, 2006, 177: 1137-1144; Journal of Power Sources, 2006, 162: 180-185; J. Membrane Science, 2006, 278: 35-42] prepared by acidifying or organically modified MMT The Nafion/mMMT composite membranes were used to improve the hydration performance and proton conductivity of these composite membranes.

In US Patent 20070072982, Yeong-suk Choi et al. used non-modified MMT to prepare nano-composite non-fluorosulfonic acid polyarylethersulfone/MMT composite membranes. The methods used included polymer intercalation composite film formation and monomer intercalation — Polymerization and compounding to form a membrane, which improves the mechanical properties of the membrane and reduces the permeation rate of polar organic fuels such as methanol in the membrane.

In CN1677732A, Zhou Zhentao and others evenly added organically modified MMT to sulfonated polymers to prepare an organic-inorganic composite proton exchange membrane, which solved the methanol permeation problem of the proton exchange membrane used in direct methanol fuel cells.

In US20050244697 and US20067008971, Karl Milton Taft III et al. used inorganic cation exchange materials to modify organic polymer electrolyte membranes, such as using clay and sulfonated polyetheretherketone blends to prepare composite membranes, which improved the mechanical strength and alcohol resistance of the membranes. Performance, its low temperature (~50°C) fuel cell performance is better than Nafion-115 membrane.

Contents of the invention

In order to overcome the shortcomings of existing proton exchange membranes in terms of high temperature stability, the object of the present invention is to provide a composite proton exchange membrane suitable for high temperature proton exchange membrane fuel cells with good high temperature stability and low cost.

The sulfonated polyarylether sulfone (ketone) proton exchange resin used in the present invention has higher thermomechanical stability and thermochemical stability; the inorganic additive is sulfonated or organic sulfonated montmorillonite, which has good affinity Water and some proton conductivity. The organic-inorganic composite membrane has the characteristics of low cost and stable structure, and also has good high-temperature proton conductivity, and can be used in high-temperature proton exchange membrane fuel cells.

In order to achieve the above object, the present invention adopts the following technical solutions:

The invention disperses the inorganic additives in the proton exchange resin to form an organic-inorganic composite proton exchange membrane; the thickness of the prepared organic-inorganic composite proton exchange membrane is between 15 and 100 μm.

Specifically:

The composite membrane is composed of organic proton exchange membrane resin and inorganic additive material, the inorganic additive material is modified montmorillonite, and its content in the membrane is 2-10wt%.

The organic proton exchange membrane resin is sulfonated polyarylether sulfone resin or sulfonated polyarylether ketone resin; the organic proton exchange membrane resin is sulfonated polyarylether sulfone (SPSU), sulfonated polyether ether ketone (SPEEK), partially fluorinated sulfonated polyarylether sulfone or partially fluorinated sulfonated polyarylether ketone, etc.

Described modified montmorillonite refers to sulfonated or organic sulfonated modified montmorillonite (SMMT), which can be obtained by conventional modification (concrete modification process can refer to document Journal of Power Sources, 2006,162: 180-185, for operation), the IEC value of the modified montmorillonite is 0.8-1.5meq./g.

The preparation steps of the organic-inorganic composite membrane are as follows:

(1) Mix the modified montmorillonite with an organic solvent, such as N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO ), 1-methyl-2-pyrrolidone (NMP), acetone or n-propanol, etc., wherein the proportion of modified montmorillonite is 1-20wt%, preferably 2-8wt%, prepared by ultrasonic vibration for 10-120 minutes to obtain a homogeneously dispersed suspension;

(2) dissolving the proton exchange resin in a solvent to form a film-making solution, wherein the resin content is 3 to 30wt.%, preferably 10 to 20wt.%; the solvent can be N, N-dimethylacetamide ( DMAC), N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO) or 1-methyl-2-pyrrolidone (NMP) and other high-boiling polar solvents, or any of them A mixed solvent composed of a low-boiling co-solvent, the content of the low-boiling co-solvent can be 5 to 30wt.%, and the low-boiling co-solvent can be acetone, propanol, isopropanol, tetrahydrofuran, etc.;

(3) Mix the suspension of the above (1) with the film-making solution of (2), and stir evenly; the weight ratio of the suspension to the film-making solution is suspension: film-making solution=1: 1～5;

(4) Pour the mixed solution prepared in step (3) on a smooth support plate, dry it on a hot table at 50-100°C for 8-24 hours, then dry it in a vacuum oven at 100°C for 3-24 hours, take it out After soaking in deionized water to remove the composite membrane after the membrane is separated; the support plate can be dense, smooth glass, metal, ceramics or plastics;

(5) Acidify the composite membrane in 0.5 mol/L H ₂ SO ₄ at 80° C. for 1 to 2 hours, and then wash it with deionized water until neutral.

The thickness of the organic-inorganic composite film prepared by the above method is generally controlled at 15-100 μm.

The composite membrane can be used as an electrolyte diaphragm of a high-temperature proton exchange membrane fuel cell, and its operating temperature is 90-150° C. when used in a high-temperature proton exchange membrane fuel cell.

In the organic-inorganic composite membrane prepared by the present invention, the proton exchange resin with proton conductivity forms a continuous phase and constitutes a proton exchange channel; the sulfonated polyarylethersulfone (ketone) resin used has higher thermomechanical stability and thermochemical stability; modified montmorillonite has good hydrophilicity and certain proton conductivity, which significantly improves the water absorption capacity of the composite membrane, slows down the dehydration of the composite membrane at high temperature, and can also improve the performance of the composite membrane. Proton conductivity; these are beneficial to improve the stability of high temperature PEMFC.

The present invention has the following advantages:

1. The cost of the composite film is low. Compared with the method reported in the literature, the basic membrane material used in the present invention is a non-fluorine proton exchange resin, and the cost is greatly reduced compared with the perfluorosulfonic acid resin. At the same time, the inorganic additive used is a clay material, which is relatively cheap, so it is very It is beneficial to reduce the material cost of the composite membrane.

2. The structure of the composite membrane is stable. Compared with the method reported in the literature, the basic membrane material used in the present invention is a non-fluorine proton exchange resin, which has higher thermal stability than perfluorosulfonic acid resin, and has better mechanical stability in a high-temperature PEMFC environment; The chemically modified montmorillonite has a larger interlayer spacing and better compatibility with the base membrane material, which are conducive to the formation and stability of the intercalation composite structure.

3. The high temperature performance of the composite film is stable. The modified montmorillonite added in the composite membrane in the present invention has good hydrophilicity and certain proton conduction ability, which significantly improves the water absorption capacity of the composite membrane, slows down the water loss of the composite membrane at high temperature, and improves the Proton conducting properties of composite membranes.

Description of drawings

In order to better understand the technical contents and implementation effects of the present invention, the following drawings are described in detail in conjunction with the embodiments:

Fig. 1 is the structural representation of the organic-inorganic composite membrane that embodiment 1 prepares, among the figure 1—organic proton exchange resin, 2—inorganic additive;

Fig. 2 is the mechanical strength comparative figure of the organic-inorganic composite membrane prepared by embodiment 1, 2 and the proton exchange membrane prepared by comparative example 1;

Fig. 3 is the comparison figure of the water loss performance of the organic-inorganic composite membrane prepared in Example 1 and the proton exchange membrane prepared in Comparative Example 1 and the modified montmorillonite;

FIG. 4 is a fuel cell polarization performance graph of the organic-inorganic composite membrane prepared in Example 1. FIG.

Detailed ways

Example 1

Stir 15g of sodium montmorillonite in 100ml of 0.5M sulfuric acid at 70°C, filter, wash with water to remove excess acid on the surface, and dry in a vacuum oven at 150°C overnight to obtain hydrogen montmorillonite (H ⁺ -MMT);

Then 2g H ⁺ -MMT and 1.35g 1,3-propane sultone were heated to reflux in toluene for 24 hours, the product was washed with toluene, filtered, and vacuum-dried at 110°C overnight to obtain organic sulfonated modified montmorillonite Soil (SMMT).

Weigh 1.0g of sulfonated polybiphenyl ether sulfone (SPSU, IEC=1.78meq./g), and dissolve it with 10g of NMP to obtain a uniform solution. Mix 0.05g SMMT (IEC=1.06meq./g) with 5g NMP, and disperse with an ultrasonic homogenizer for 90 minutes to obtain a uniform suspension. Mix the SMMT/NMP suspension with the SPSU/NMP solution and stir for 10 minutes to remove air bubbles. The SPSU/NMP solution containing SMMT was poured on a glass plate, heated on a hot stage at 60°C for 3 hours, 80°C for 3 hours, 100°C overnight, and heated in a vacuum oven at 100°C for 8 hours. After taking it out, soak it in deionized water to separate the membrane, then take off the composite membrane to obtain a SMMT/SPSU composite membrane with a thickness of 50 μm. Its SMMT content is 5% (wt.).

Soak the composite membrane in 0.5 mol/L H ₂ SO ₄ at 80°C to acidify for 1 to 2 hours, and then wash it with deionized water until it is neutral.

Comparative example 1

Weigh 1.0 g of sulfonated polybiphenyl ether sulfone (SPSU), and dissolve it with 10 g of NMP to obtain a uniform solution. The SPSU/NMP solution was poured on a glass plate, heated on a hot stage at 60°C for 3 hours, 80°C for 3 hours, 100°C overnight, and heated in a vacuum oven at 100°C for 8 hours. After taking it out, soak it in deionized water to separate the membrane and remove the composite membrane to obtain an SPSU membrane with a thickness of 50 μm. The membrane was acidified by the same acidification method as in Example 1 and set aside.

Example 2

Weigh 1.0 g of sulfonated polybiphenyl ether sulfone (SPSU, IEC=1.78 meq./g) and dissolve it with 10 g of NMP to prepare a uniform solution. Mix 0.03g SMMT (IEC=1.06meq./g) with 5g NMP, and disperse for 90 minutes with an ultrasonic homogenizer to obtain a uniform suspension. Mix the SMMT/NMP suspension with the SPSU/NMP solution and stir for 10 minutes to remove air bubbles. The SPSU/NMP solution containing SMMT was poured on a glass plate, heated on a hot stage at 60°C for 3 hours, 80°C for 3 hours, 100°C overnight, and heated in a vacuum oven at 100°C for 8 hours. After taking it out, soak it in deionized water to separate the membrane, then take off the composite membrane to obtain a SMMT/SPSU composite membrane with a thickness of 50 μm. Its SMMT content is 3% (wt.).

Soak the composite membrane in 0.5 mol/L H ₂ SO ₄ at 80°C to acidify for 1 to 2 hours, and then wash it with deionized water until it is neutral.

Example 3

Weigh 1.0g sulfonated polybiphenyl ether sulfone (SPSU, IEC=1.78meq./g) and dissolve it with 10g NMP to obtain a uniform solution. Mix 0.10g SMMT (IEC=1.26meq./g) with 5g NMP, and disperse with an ultrasonic homogenizer for 90 minutes to obtain a uniform suspension. Mix the SMMT/NMP suspension with the SPSU/NMP solution and stir for 10 minutes to remove air bubbles. The SPSU/NMP solution containing SMMT was poured on a glass plate, heated on a hot stage at 60°C for 3 hours, 80°C for 3 hours, 100°C overnight, and heated in a vacuum oven at 100°C for 8 hours. After taking it out, soak it in deionized water to separate the membrane, then take off the composite membrane to obtain a SMMT/SPSU composite membrane with a thickness of 60 μm. Its SMMT content is 10% (wt.).

Soak the composite membrane in 0.5 mol/L H ₂ SO ₄ at 80°C to acidify for 1 to 2 hours, and then wash it with deionized water until it is neutral.

Example 4

A single-section H ₂ /O ₂ fuel cell with an electrode area of 0.5 cm ² is used: the electrode is a porous gas diffusion electrode, and the amount of platinum loaded for the cathode and anode is 0.7 mg/cm ² and 0.3 mg/cm ² respectively, and the membrane/ The three-in-one electrode (MEA) is made by hot pressing at 1-2MPa and 140°C for 2 minutes. Battery performance test: use hydrogen and oxygen as fuel and oxidant respectively, adopt reaction gas entrained humidification method, adjust the gas pressure to 0.1-0.25MPa; by adjusting the resistance of the external circuit, record the corresponding current and voltage values, and obtain the battery electrode accordingly. curve.

Claims (5)

1. A composite membrane, characterized in that: it is made up of organic proton exchange membrane resin and inorganic additive material, and described inorganic additive material is modified montmorillonite, and its content in membrane is 2～10wt%. 2. The composite membrane according to claim 1, characterized in that: said organic proton exchange membrane resin is sulfonated polyarylether sulfone resin, sulfonated polyarylether ketone resin, partially fluorinated sulfonated polyarylether sulfone or Partially fluorinated sulfonated polyaryletherketone. 3. according to the described composite membrane of claim 1, it is characterized in that: described modified montmorillonite refers to the montmorillonite modified by sulfonation or organic sulfonation, which can be modified by conventional methods, and modified montmorillonite The IEC value of soil removal is 0.8-1.5meq./g. 4. An application of the composite membrane in claim 1 in a high-temperature proton exchange membrane fuel cell, characterized in that: the composite membrane can be used as an electrolyte diaphragm of a high-temperature proton exchange membrane fuel cell. 5. The application according to claim 4, wherein the operating temperature of the electrolyte diaphragm is 90-150°C when used in a high-temperature proton exchange membrane fuel cell.

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