CN110504472A - A direct methanol fuel cell membrane electrode for improving catalyst utilization and its preparation method - Google Patents

Abstract

The invention discloses a direct methanol fuel cell membrane electrode capable of improving catalyst utilization and a preparation method thereof, and relates to the technical field of fuel cells. In the fuel cell membrane electrode prepared by the method of the invention, the microporous layer has a double-layer structure. It includes an outer microporous layer comprising a hydrophobic polymer, and an inner microporous layer comprising a proton-conducting polymer. This double microporous layer structure has a high three-phase reaction interface and electrochemical reaction area, which can effectively reduce the material transport resistance inside the electrode, effectively improve the utilization rate of the catalyst, thereby improving the discharge performance of the electrode and prolonging the life of the battery. Through the single cell performance test, the membrane electrode prepared by the preparation method of the present invention is significantly improved in monomer performance compared with the membrane electrode prepared by the traditional method.

Description

A direct methanol fuel cell membrane electrode with improved catalyst utilization and its preparation method

technical field

The invention relates to the technical field of fuel cells, in particular to a direct methanol fuel cell membrane electrode capable of improving catalyst utilization and a preparation method thereof.

Background technique

Direct Methanol Fuel Cell (DMFC) is a power generation device that can continuously and directly convert the chemical energy in fuel and oxidant into electrical energy. Due to its environmental protection and high efficiency, it has attracted worldwide attention. Methanol fuel cells directly use methanol or methanol aqueous solution as the anode fuel, and oxygen or air as the oxidant. Because of its wide source of methanol, easy to carry, convenient storage and replenishment, high volume and mass specific energy, simple structure, no need for external reforming equipment, etc., it has broad applications in portable power supplies, small civil power supplies and vehicle power supplies. Application prospects.

Membrane electrode, as the core component of direct methanol fuel cell, directly determines the performance of the cell. However, the current DMFC has the problem of low electrocatalytic activity of the methanol anode. Methanol oxidation mechanism is very complex, some unstable and insoluble intermediate products will be generated in this process, some intermediate products will be adsorbed on the surface of the catalyst, inhibiting the activity of the catalyst, resulting in catalyst poisoning and low catalyst utilization . Therefore, it is a hotspot in DMFC research to optimize the membrane electrode structure, improve catalyst utilization and electrochemical reaction area.

Most of the current work focuses on the modification of the catalyst support or the structure of the catalytic layer, but the problem of battery performance degradation due to catalyst sinking caused by assembly pressure, methanol flow, and gas flow remains to be solved. When the battery runs for a period of time, some catalysts cannot The ionic polymer contacts, so that the protons cannot be transferred, and the catalyst cannot work, so the electrode has a large electrochemical reaction resistance, resulting in a decrease in battery performance. In view of this, we constructed a new type of double microporous membrane electrode. The dual microporous layer consists of an inner microporous layer (added with Nafion polymer) and an outer microporous layer (added with PTFE polymer). The existence of the inner microporous layer can expand the three-phase interface area of the reaction and improve the utilization rate of the catalyst.

Contents of the invention

The purpose of the present invention is to provide a direct methanol fuel cell membrane electrode with improved catalyst utilization, so as to increase the three-phase reaction interface and electrochemical active area, improve the catalyst utilization, and reduce the electrochemical reaction resistance and mass transfer of the electrode Resistance, the purpose of improving the performance of the single cell.

Technical scheme of the present invention is as follows:

A direct methanol fuel cell membrane electrode capable of improving catalyst utilization, comprising a direct methanol fuel cell membrane electrode, a microporous layer is prepared on the direct methanol fuel cell membrane electrode, and the microporous layer has a double-layer structure including a an outer microporous layer comprising a hydrophobic polymer and an inner microporous layer comprising a proton-conducting polymer;

A method for preparing a double-microporous membrane electrode, comprising the steps of:

Step 1: Treatment of the gas diffusion layer

Soak the gas diffusion layer in a certain concentration of hydrophobic polymer solution for 30 seconds to 90 seconds, put the gas diffusion layer in an oven to dry, and after the gas diffusion layer is dried, put it into a muffle furnace for sintering to obtain a surface Hydrophobic gas diffusion layer, wherein the mass fraction of hydrophobic polymer on the gas diffusion layer is 20wt.%-40wt.%.

Step 2: Preparation of the outer microporous layer

The surface hydrophobic gas diffusion layer obtained in step 1) is evenly sprayed with a slurry containing carbon powder and a hydrophobic polymer, and the carbon paper sprayed with the slurry is put into an oven for drying, and then put into a muffle furnace for Sintering to obtain the outer microporous layer, the mass fraction of polytetrafluoroethylene in the outer microporous layer is 15wt.%-30wt.%.

Step 3: Preparation of inner microporous layer

The surface of the outer microporous layer obtained in step 2) is evenly sprayed with carbon powder and a slurry of a polymer with proton conductivity, and the microporous layer sprayed with the slurry is put into an oven for drying, and the polymer with proton conductivity The mass fraction of the polymer in the inner microporous layer is 20wt.%-40wt.%, thereby obtaining a microporous layer with a double-layer structure.

Step 4: Preparation of the catalytic layer

The microporous layer of the double-layer structure obtained in step 3) is uniformly coated with a catalyst slurry containing a proton conductor, and the catalyst is Pt/C or PtRu/C with a metal weight percentage of 40wt.%-70wt.%. After spraying, it is put into an oven for a period of time until it is dried, and the electrode of the direct methanol fuel cell with improved catalyst utilization rate is obtained.

Step 5: Membrane Electrode Assembly

Pressing the electrode of the direct methanol fuel cell with improved catalyst utilization obtained in step 4) and the proton exchange membrane with ion conductivity, the pressing pressure is 6.0N·m-8.0N·m, and pressing at room temperature without By hot pressing, the direct methanol fuel cell membrane electrode with improved catalyst utilization can be obtained.

Further, in step 1), the gas diffusion layer is immersed in the hydrophobic polymer for 30-90 seconds, and the sintering temperature in the muffle furnace is 350-400 degrees for 40-60 minutes.

Further, the gas diffusion layer in step 1) is carbon paper, carbon cloth, nickel foam or other conductive materials after removing surface impurities.

Further, the hydrophobic polymer in step 1) is polytetrafluoroethylene or polyvinyl alcohol or polyvinylidene fluoride, and the mass fraction of the hydrophobic polymer on the gas diffusion layer is 20wt.%-40wt.%.

Further, the slurry component in step 2) is a mixed solution of carbon powder, hydrophobic polymer, and dispersing solvent; wherein, the mass fraction of the hydrophobic polymer in the outer microporous layer is 15wt.%-30wt.%.

Further, the slurry component in step 3) is a mixed solution of carbon powder, a polymer with proton conductivity, and a dispersion solvent, wherein the volume of the dispersion solvent is 5-10 ml.

Further, the polymer with proton conductivity in step 3) is perfluorosulfonic acid-polytetrafluoroethylene, and the dispersion solvent is isopropanol, ethanol, acetone; wherein, perfluorosulfonic acid-polytetrafluoroethylene is micro The mass fraction in the hole layer is 20wt.%-40wt.%.

Further, the anode catalyst in step 4) is Pt/C or PtRu/C with a metal weight percentage of 40wt.%-70wt.%, and the metal loading in the anode catalyst layer is 2mg cm ^- 2-5mg cm ^-2 ; The cathode catalyst is Pt/C or PtRu/C with a metal weight percentage of 40wt.%-70wt.%, and the metal loading in the cathode catalyst layer is 1.5mg cm ^-2 -3mg cm ^-2 .

Further, the mass fraction of the proton conductor in the catalytic layer in step 4) is 25wt.%-40wt.%.

Further, the proton exchange membrane described in step 5) is a perfluorosulfonic acid membrane, and the pressing condition of the electrode of the direct methanol fuel cell and the proton exchange membrane is a pressure of 6.0N·m-8.0N·m, and the pressing is carried out at room temperature.

(1) Treatment of the gas diffusion layer

Soak the gas diffusion layer in a polytetrafluoroethylene solution of a certain concentration for 30 seconds, put the carbon paper in an oven to dry, and after the carbon paper is dried, put it in a muffle furnace for sintering to obtain a carbon paper with a hydrophobic surface. Wherein the mass fraction of polytetrafluoroethylene on the gas diffusion layer is 20wt.%-30wt.%.

(2) Preparation of outer microporous layer

The surface hydrophobic carbon paper obtained in step (1) is evenly sprayed with a slurry containing carbon powder and polytetrafluoroethylene, and the carbon paper sprayed with the slurry is put into an oven for drying, and then put into a muffle furnace for Sintering to obtain the outer microporous layer, the mass fraction of polytetrafluoroethylene in the outer microporous layer is 15wt.%-20wt.%.

(3) Preparation of inner microporous layer

The surface of the outer microporous layer obtained in step (2) is uniformly sprayed with a slurry of carbon powder and perfluorosulfonic acid-polytetrafluoroethylene (Nafion) copolymer, and the microporous layer sprayed with the slurry is put into an oven After drying, the mass fraction of Nafion in the inner microporous layer is 25wt.%-35wt.%, thereby obtaining a microporous layer with a double-layer structure.

(4) Preparation of catalytic layer

The microporous layer of the double-layer structure obtained in step (3) is evenly coated with a catalyst slurry containing a proton conductor, and the catalyst is Pt/C or PtRu/C with a weight percentage of metal of 40wt.%-70wt.%. After spraying, put it in an oven and keep it for a period of time until it is dried, that is, the electrode of the direct methanol fuel cell with improved catalyst utilization can be obtained.

(5) Assembly of Membrane Electrode

Pressing the electrode of the direct methanol fuel cell obtained in step (4) to improve the utilization rate of the catalyst and the proton exchange membrane with ion conductivity, the pressing pressure is 7.5N·m, pressing at room temperature without hot pressing, that is A direct methanol fuel cell membrane electrode with improved catalyst utilization is obtained.

Compared with the traditional single microporous layer membrane electrode, the double microporous layer membrane electrode proposed by the present invention has the following advantages:

(1) Larger electrochemical active area

When the battery runs for a period of time, due to the influence of assembly pressure, methanol feed and gas flow, a part of the catalyst will sink into the microporous layer. The structure of the conventional electrode single microporous layer does not contain proton conductors, which makes This part of the catalyst is not utilized, thereby reducing the three-phase reaction interface. However, in the double microporous layer electrode proposed by the present invention, since the proton conductor is added in the inner microporous layer, this part of the catalyst can be utilized, thereby enlarging the electrochemically active area.

(2) Higher catalyst utilization

However, the inner microporous layer of the present invention makes use of the part of the catalyst leaked into the microporous layer, improves the utilization rate of the catalyst, and thus greatly reduces the preparation cost of the electrode.

(3) Lower mass transfer resistance

The single microporous layer of conventional electrodes is usually a hydrophobic structure, which makes it difficult to feed methanol at low concentrations, increases the mass transfer resistance in the electrode, and affects the performance of the single cell. The double microporous layer of the present invention is added with Nafion polymer, which has a high degree of hydrophilicity, strengthens the transmission of methanol, and reduces the mass transfer resistance of the electrode.

Description of drawings

Fig. 1 is the direct methanol fuel cell membrane electrode structure schematic diagram that improves catalyst utilization rate of the present invention;

Fig. 2 is the flow chart of the preparation process of the direct methanol fuel cell electrode for improving the catalyst utilization rate of the present invention;

Fig. 3 is the flow chart of the direct methanol fuel cell membrane electrode assembly process of improving the catalyst utilization rate of the present invention;

Fig. 4 is the fuel cell discharge performance curve of embodiment 1;

Fig. 5 is the discharge performance curve of the fuel cell of embodiment 2;

Fig. 6 is the fuel cell discharge performance curve of embodiment 3;

Fig. 7 is the discharge performance curve of the fuel cell of embodiment 4;

Fig. 8 is the discharge performance curve of the fuel cell of Comparative Example 1;

Fig. 9 is the discharge performance curve of the fuel cell of Comparative Example 2;

Fig. 10 is the discharge performance curve of the fuel cell of Comparative Example 3;

Fig. 11 is the discharge performance curve of the fuel cell of Comparative Example 4.

The reference signs are as follows:

1-gas diffusion layer; 2-microporous layer containing PTFE; 3-microporous layer containing Nafion; 4-anode catalyst layer; 5-proton exchange membrane; 6-cathode catalyst layer.

Detailed ways

Example 1

According to the process and process shown in Figure 2 to prepare direct methanol fuel cell electrodes and membrane electrodes with improved catalyst utilization, and conduct discharge tests, the main steps are as follows:

(1) Preparation of electrodes

Carbon paper containing polytetrafluoroethylene (PTFE) is used as a diffusion layer, and a microporous layer 2 containing PTFE is coated on the hydrophobic diffusion layer, wherein the content of polytetrafluoroethylene is 15 wt.%. A microporous layer 3 containing Nafion is coated on the outer microporous layer, wherein the content of Nafion is 30wt.%. Prepare the appropriate proportion of catalyst slurry, using isopropanol as solvent. Use PtRu/C as a catalyst on the anode side and Pt/C as a catalyst on the cathode side, and spray catalyst slurry on the microporous layer 3 containing Nafion to form a catalyst layer.

(2) Treatment of proton exchange membrane

The membrane was boiled in ₅ wt.% H2O2 solution for ₁ hour, then washed in deionized water, then boiled in 0.5 M sulfuric acid solution for 1 hour, and finally boiled in deionized water for 1 hour. Pretreated membranes were kept in deionized water prior to pressing the MEA.

(3) Membrane electrode assembly

Press two electrodes with double microporous layer structure and Nafion 212 membrane, the pressing condition is pressure 7.5N·m, just press at room temperature, without hot pressing, the improved catalyst utilization rate of the present invention can be obtained Membrane electrodes for direct methanol fuel cells.

(4) Discharge performance test

The obtained membrane electrode assembly and sealing air cushion were assembled in a single cell and then tested. The test conditions were: cell operating temperature 60°C, normal pressure, anode fuel 0.5M methanol (flow 3ml min ^-1 ), cathode air intake was dry Oxygen (flow rate 199ml min ^-1 ). The limiting current density can reach 120.17mA cm ^-2 , and the maximum power density can reach 22.23mW cm ^-2 . Compared with Comparative Example 1, the maximum power density of Example 1 is increased by 56.53%.

Example 2

The direct methanol fuel cell membrane electrode of the catalyst utilization rate of the present invention is tested under the conditions of high concentration methanol and dry oxygen. First, a double microporous layer electrode was prepared according to the same procedure as in Example 1.

The obtained membrane electrode assembly and sealing air cushion were assembled in a single cell and then tested. The test conditions were: cell operating temperature 60°C, normal pressure, anode fuel was 2M methanol (flow rate: 3ml min ^-1 ), cathode gas intake was dry oxygen (The flow rate is 199ml min ^-1 ). The limiting current density can reach 500.21mA cm ^-2 , and the maximum power density can reach 76.29mW cm ^-2 , which is 41.01% higher in Example 2 than in Comparative Example 2.

Example 3

The direct methanol fuel cell membrane electrode of the catalyst utilization rate of the present invention is tested under the conditions of low concentration of methanol and humidified oxygen. First, a double microporous layer electrode was prepared according to the same procedure as in Example 1.

The obtained membrane electrode assembly and sealing air cushion were assembled in a single cell and then tested. The test conditions were: cell operating temperature 60°C, normal pressure, anode fuel was 0.5M methanol (flow rate: 3ml min ^-1 ), cathode intake air was humidified Oxygen (relative humidity 60%, flow rate 199ml min ^-1 ). The limiting current density can reach 135.05mA cm ^-2 , and the maximum power density can reach 29.12mW cm ^-2 , which is 97.38% higher in Example 3 than in Comparative Example 3.

Example 4

The direct methanol fuel cell membrane electrode of the catalyst utilization rate of the present invention is tested under the conditions of high concentration methanol and humidified oxygen. First, a double microporous layer electrode was prepared according to the same procedure as in Example 1.

The obtained membrane electrode assembly and sealing air cushion were assembled in a single cell and then tested. The test conditions were: cell operating temperature 60°C, normal pressure, anode fuel was 2M methanol (flow rate: 3ml min ^-1 ), cathode intake air was humidified oxygen (The relative humidity is 60%, the flow rate is 199ml min ^-1 ). The limiting current density can reach 550.12mA cm ^-2 , and the maximum power density can reach 81.04mW cm ^-2 , which is 36.65% higher in Example 4 than in Comparative Example 4.

Comparative example 1

The fuel cell electrode and membrane electrode with conventional microporous layer structure were prepared to compare the discharge performance. Proceed as follows:

(1) Membrane electrode preparation: carbon paper containing polytetrafluoroethylene (PTFE) was used as the anode diffusion layer. An outer microporous layer with a polytetrafluoroethylene content of 15 wt. % was coated on the hydrophobic diffusion layer. Catalyst slurry was prepared by dispersing appropriate amount of catalyst in deionized water, isopropanol and Nafion solution. Pt Ru/C was used as a catalyst on the anode side and Pt/C was used as a catalyst on the cathode side. The catalyst slurry is coated on the microporous layer to form a catalyst layer. Pretreatment of Nafion 212 membranes to remove organic and inorganic contaminants. The pretreatment process consisted of boiling the membrane in ₅ wt% H2O2 solution for ₁ h, then washing in deionized water, then boiling in 0.5 M sulfuric acid solution for 1 h, and finally boiling in deionized water for 1 h. Before assembling the MEA, keep the pretreated membrane in deionized water.

(2) Membrane electrode assembly: the electrolyte membrane is Nafion 212 membrane. Two prepared identical gas diffusion electrodes are placed on both sides of the electrolyte membrane, and pressed together with an assembly pressure of 7.5N m to obtain a three-in-one membrane electrode components.

(3) Single cell test: The obtained three-in-one membrane-electrode assembly and the sealing air cushion were assembled in a single cell and tested under the same test conditions as in Example 1. The limiting current density reaches 99.98mA cm ^-2 , and the maximum power density reaches 14.20mW cm ^-2 .

Comparative example 2

The fuel cell electrode and membrane electrode with conventional microporous layer structure were compared in discharge performance under the condition of high concentration of methanol and dry oxygen.

First, fuel cell electrodes and membrane electrodes with a conventional microporous layer structure were prepared and assembled according to the same procedures as in Comparative Example 1. The obtained three-in-one membrane-electrode assembly and the sealing air cushion were assembled in a single cell and tested under the same test conditions as in Example 2. The limiting current density reaches 350.07mA cm ^-2 , and the maximum power density reaches 54.11mW cm ^-2 .

Comparative example 3

The fuel cell electrode and membrane electrode with conventional microporous layer structure were compared in discharge performance under the condition of low concentration of methanol and humidified oxygen.

First, fuel cell electrodes and membrane electrodes with a conventional microporous layer structure were prepared and assembled according to the same procedures as in Comparative Example 1. The obtained three-in-one membrane-electrode assembly and the sealing air cushion were assembled in a single cell and tested under the same test conditions as in Example 3. The limiting current density reaches 82.34mA cm ^-2 , and the maximum power density reaches 14.75mW cm ^-2 .

Comparative example 4

The fuel cell electrode and membrane electrode with conventional microporous layer structure were compared in discharge performance under the condition of low concentration of methanol and humidified oxygen.

First, fuel cell electrodes and membrane electrodes with a conventional microporous layer structure were prepared and assembled according to the same procedures as in Comparative Example 1. The obtained three-in-one membrane-electrode assembly and the sealing air cushion were assembled in a single cell and tested under the same test conditions as in Example 4. The limiting current density reaches 375.04mA cm ^-2 , and the maximum power density reaches 59.30mW cm ^-2 .

It can be seen from the comparison examples that the direct methanol fuel cell electrode and membrane electrode with improved catalyst utilization rate in the present invention have better discharge performance. At 60°C, no matter whether it is humidification or drying, compared with the comparative example, the maximum discharge current density and the maximum power density of the embodiment are greatly improved. Compared with the comparative example 1, the maximum power density of the embodiment 1 is Increased by 56.53%; Example 2 increased by 41.01% compared to Comparative Example 2; Example 3 increased by 97.38% compared to Comparative Example 3; Example 4 increased by 36.65% compared to Comparative Example 4. It shows that the addition of the inner microporous layer makes part of the unusable catalyst that seeps down to the microporous layer due to the operation of the battery to be utilized, and the utilization rate of the catalyst is improved. This double microporous layer structure increases the electrochemically active area of the battery, reduces the mass transfer resistance, promotes the electrochemical reaction efficiency and mass transfer, and effectively improves the discharge performance of the battery.

It should be noted that, according to the various embodiments of the present invention, those skilled in the art can fully realize the full scope of the independent claims and dependent claims of the present invention, and the implementation process and method are the same as the above-mentioned embodiments; and the present invention is not elaborated Some of them belong to well-known technologies in the art.

The above is only part of the specific implementation of the present invention, but the scope of protection of the present invention is not limited thereto, any person familiar with the art within the technical scope disclosed in the present invention, can be replaced in the changes that can be easily imagined, all should covered within the protection scope of the present invention.

Claims (11)

1. a kind of direct methanol fuel cell membrane electrode for improving catalyst utilization, including gas diffusion layers, microporous layers, catalysis Layer and proton exchange membrane, which is characterized in that the microporous layers of direct methanol fuel cell membrane electrode have double-layer structure, including one layer The interior microporous layers of outer microporous layers containing hydrophobic polymer and one layer of polymer with proton conductivity.

2. improving the preparation method of the direct methanol fuel cell membrane electrode of catalyst utilization, feature according to claim 1 It is, includes the following steps:

Step 1: the processing of gas diffusion layers: gas diffusion layers being immersed in the solution of certain density hydrophobic polymer, After being soaked for a period of time, gas diffusion layers are placed in oven and dried, Muffle furnace is put into after gas diffusion layers drying and is burnt Knot, obtains the gas diffusion layers of surface hydrophobicity；

Step 2: the preparation of outer microporous layers: by step 1) obtained in surface hydrophobicity gas diffusion layers even application on contain The slurry of carbon dust and hydrophobic polymer, by the gas diffusion layers for spraying spreading mass be put into baking oven drying, after be put into Muffle furnace into Row sintering, obtains outer microporous layers；

Step 3: the preparation of interior microporous layers: by step 2) obtained in carbon dust and there is matter on outer micropore layer surface even application The microporous layers for spraying spreading mass are put into baking oven drying by the slurry of the polymer of sub- conducting power, and obtaining has double-layer structure Microporous layers；

Step 4: the preparation of Catalytic Layer: by step 3) in obtained double-layer structure microporous layers on uniformly it is coated containing proton The catalyst pulp of conductor, and be put into baking oven and kept for a period of time until drying, that is, obtain and improve the straight of catalyst utilization Connect the electrode of methanol fuel cell；

Step 5: the assembling of membrane electrode: by step 4) obtained in raising catalyst utilization direct methanol fuel cell Electrode presses to arrive the direct methanol fuel electricity for improving catalyst utilization with the proton exchange membrane with ionic conductivity Pond membrane electrode.

3. improving the preparation method of the direct methanol fuel cell membrane electrode of catalyst utilization, feature according to claim 2 Be, step 1) in gas diffusion layers to be immersed in time in hydrophobic polymer be 30~90 seconds, the sintering in Muffle furnace Temperature is 350-400 degree, and the time is 40~60 minutes.

4. improving the preparation method of the direct methanol fuel cell membrane electrode of catalyst utilization, feature according to claim 2 Be, step 1) in gas diffusion layers be by the removal carbon paper of surface impurity, carbon cloth, nickel foam or other there is conduction The material of ability.

5. improving the preparation method of the direct methanol fuel cell membrane electrode of catalyst utilization, feature according to claim 2 Be, step 1) in hydrophobic polymer be polytetrafluoroethylene (PTFE) or polyvinyl alcohol or Kynoar, hydrophobic polymeric The mass fraction of object on the gas diffusion is 20wt.%~40wt.%.

6. improving the preparation method of the direct methanol fuel cell membrane electrode of catalyst utilization, feature according to claim 2 Be, step 2) in paste composition be carbon dust, hydrophobic polymer, dispersion solvent mixed solution；Wherein, hydrophobic polymeric Mass fraction of the object in outer microporous layers is 15wt.%-30wt.%.

7. improving the preparation method of the direct methanol fuel cell membrane electrode of catalyst utilization, feature according to claim 2 Be, step 3) in paste composition be carbon dust, the polymer with proton conductivity, dispersion solvent mixed solution, wherein The volume of dispersion solvent is in 5-10ml.

8. improving the preparation method of the direct methanol fuel cell membrane electrode of catalyst utilization, feature according to claim 7 Be, step 3) in proton conductivity polymer be perfluorinated sulfonic acid-polytetrafluoroethylene (PTFE), dispersion solvent be isopropanol, Ethyl alcohol, acetone；Wherein, mass fraction of the perfluorinated sulfonic acid-polytetrafluoroethylene (PTFE) in interior microporous layers is 20wt.%~40wt.%.

9. improving the preparation method of the direct methanol fuel cell membrane electrode of catalyst utilization, feature according to claim 2 Be, step 4) in anode catalyst be metal weight percent be 40wt.%-70wt.% Pt/C or PtRu/C, Metal ladings are 2mg cm in anode catalyst layer^-2-5mg cm^-2；Cathod catalyst is that the weight percent of metal is 40wt.%- The Pt/C or PtRu/C of 70wt.%, metal ladings are 1.5mg cm in cathode catalysis layer^-2-3mg cm^-2。

10. according to the preparation method of the direct methanol fuel cell membrane electrode of claim 2 catalyst utilization, feature exists In step 4) in Catalytic Layer mass fraction shared by proton conductor be 25wt.%-40wt.%.

11. according to the preparation method of the direct methanol fuel cell membrane electrode of claim 2 catalyst utilization, feature exists In step 5) described in proton exchange membrane be perfluoro sulfonic acid membrane, the electrode of direct methanol fuel cell and the pressure of proton exchange membrane Conjunction condition is pressure 6.0N m~8.0N m, is suppressed at room temperature.