CN112825366A

CN112825366A - High-temperature proton membrane fuel cell membrane electrode based on hydrogen-poor reformed gas feeding, preparation and application

Info

Publication number: CN112825366A
Application number: CN201911149914.3A
Authority: CN
Inventors: 王素力; 李焕巧; 孙公权
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2019-11-21
Filing date: 2019-11-21
Publication date: 2021-05-21

Abstract

The invention belongs to the field of electrochemical energy, and in particular relates to a membrane electrode for a high-temperature proton membrane fuel cell based on hydrogen-depleted reformed gas feeding, and its preparation and application. The anode is a gas diffusion electrode coated with a mixed layer of hydrogen oxidation electrocatalyst and CO conversion catalyst on the surface of the gas diffusion layer facing the membrane, and the cathode is a gas diffusion electrode coated with a cathode catalyst layer on the surface of the gas diffusion layer facing the membrane. The direct feeding of hydrogen-depleted reformed gas can be realized, and the discharge performance of the fuel cell has little effect.

Description

High-temperature proton membrane fuel cell membrane electrode based on hydrogen-poor reformed gas feeding, preparation and application

Technical Field

The invention belongs to the field of electrochemical energy, and particularly relates to a high-temperature proton membrane fuel cell membrane electrode based on hydrogen-poor reformed gas feeding and a preparation method thereof

Background art:

the fuel cell is a reaction device which directly converts chemical energy in fuel and oxidant molecules into electric energy through electrocatalysis reaction in a porous electrode, is not limited by Carnot cycle, and is efficientA power generation technology. Conventional Proton Exchange Membrane Fuel Cells (PEMFCs) use hydrogen as a fuel, and are limited by the operating temperature range of the solid proton exchange membrane (e.g., Nafion membrane), and the operating temperature of the PEMFC is generally not higher than 80 ℃. The PEMFC mainly adopts Pt metal nanoparticles as catalysts for anode hydrogen oxidation reaction and cathode oxygen reduction reaction. The PEMFC anode hydrogen is mainly obtained by catalytic reforming of liquid fuels such as methanol or ethanol, however, the CO concentration in the reformed gas is high (1-3%), so that the anode Pt catalyst is easily poisoned, and the battery discharge performance is poor. The CO poisoning effect of the Pt catalyst can be reduced or eliminated by increasing the operation temperature, for example, in a high-temperature proton membrane fuel cell, the cell temperature can be increased to 150 ℃ to 200 ℃ by introducing a high-temperature PBI membrane, and further reformed gas can be directly used for feeding without an additional hydrogen purification device. For example, CN 206340609U discloses a methanol-based external reforming fuel cell system, which mainly comprises an evaporator, a reforming chamber and a high-temperature fuel cell stack, wherein the evaporator is connected with the reforming chamber, a gas outlet of the reforming chamber is connected with an inlet of the high-temperature fuel cell stack, and reformed hydrogen, CO of methanol₂And the steam enters the galvanic pile to react to release electric energy. CN 105720288B discloses a methanol internal reforming fuel cell stack, in which a methanol reforming chamber is located between adjacent anode plate and cathode plate in the fuel cell stack, and the system realizes efficient heat utilization by controlling heat matching between fuel cell heat release and reforming reaction heat absorption, and improves system efficiency of high temperature reforming fuel cell.

In summary, the high temperature membrane fuel cell based on the reformed gas feed has many advantages, but the technology is still in the initial stage of development, and the technologies are still not mature. Due to the difference of fuels and reforming methods, the quality of the reformed gas has obvious difference, and the discharge performance of the fuel cell is obviously deteriorated and sometimes even can not discharge stably along with the reduction of the hydrogen content and the increase of the CO content in the reformed gas. So far, the high-temperature membrane electrode aiming at reformed gas feeding is mostly suitable for hydrogen-rich gas (hydrogen content > 75%, CO content < 1%) of methanol reforming, and the component and structural design of the membrane electrode aiming at reformed gas with poor hydrogen and high CO content is lacked.

In view of the above problems, the present invention aims to provide a high temperature proton membrane fuel cell membrane electrode based on hydrogen-deficient reformed gas feed, which is characterized in that:

the membrane electrode comprises an anode, a phosphoric acid-impregnated PBI membrane and a cathode which are sequentially stacked, wherein the anode is a gas diffusion electrode of which the surface of one side, facing the membrane, of a gas diffusion layer is coated with a hydrogen oxidation electrocatalyst and CO conversion catalyst mixed layer, and the cathode is a gas diffusion electrode of which the surface of one side, facing the membrane, of the gas diffusion layer is coated with a cathode catalyst layer.

The anode hydrogen oxidation electrocatalyst is one or the combination of more than two of Pt/C or Pt black electrocatalyst with the mass loading of 20-60%;

the Pt loading capacity of the anode hydrogen oxidation electrocatalyst is 0.5-2mg/cm²；

The CO conversion catalyst is one or the combination of more than two of RuNi/C, RuNi black with 20-60% of active metal mass loading, AuNi/C, AuNi black with 20-60% of active metal mass loading and IrNi/C, IrNi black with 20-60% of active metal mass loading; the molar ratio of the noble metal to the Ni in the active metal is 1:1 to 3: 1;

the active metal loading of the CO conversion catalyst is 0.1-0.5mg/cm²。

The cathode catalyst is one or the combination of more than two of Pt/C, Pt black with the mass loading of 20-60%, PtCo/C with the mass loading of 20-60% and PtNi/C electrocatalyst with the mass loading of 20-60%; the molar ratio of Pt to Co or Ni in the active metal is 1:1 to 3: 1;

the Pt loading capacity of the cathode is 0.5-3mg/cm²。

A high-temperature proton membrane fuel cell membrane electrode based on hydrogen-poor reformed gas feeding is characterized in that a gas diffusion layer is one of carbon paper, carbon cloth and conductive carbon felt, wherein the surface of one side, facing the membrane, of the gas diffusion layer is coated with a carbon powder and adhesive PTFE mixed layer; the carbon powder loading capacity is 1-3mg/cm²Binder PTFE carrying capacity of 0.1-0.3mgcm²；

The content of phosphoric acid in the PBI-phosphoric acid doped membrane is 300-500 wt%.

A high-temperature proton membrane fuel cell membrane electrode based on hydrogen-poor reformed gas feeding comprises the following steps:

preparing a gas diffusion layer: coating carbon powder and a PTFE (polytetrafluoroethylene) mixed layer serving as a binder on the surfaces of the carbon paper, the carbon cloth and the conductive carbon felt facing one side of the membrane, and drying and carrying out heat treatment to obtain a gas diffusion layer;

the preparation method of the diffusion layer slurry comprises the steps of weighing carbon powder and PTFE emulsion, mechanically stirring at a high speed, and uniformly dispersing in an alcohol-water mixed solution, wherein the mass concentrations of the carbon powder and the PTFE in the slurry are 20-40mg/mL and 5-20 mg/mL; the mass ratio of the carbon powder to the PTFE in the diffusion layer is 9:1-6: 4; the carbon powder loading in the diffusion layer is 1-3mg/cm²The loading amount of the adhesive PTFE is 0.1-0.3mg/cm²。

Coating catalyst slurry of a cathode and an anode on the surface of the gas diffusion layer, and drying, heat treating and activating to obtain a gas diffusion electrode; placing the gas diffusion electrodes on two sides of a PBI membrane soaked with phosphoric acid for hot pressing to obtain a membrane electrode;

the anode catalyst slurry is a dispersion of a hydrogen oxidation electric catalyst, a CO conversion catalyst and PTFE in an alcohol-water mixed solvent; the cathode catalyst slurry is a dispersion liquid of an oxygen reduction electrocatalyst and PTFE in an alcohol-water mixed solvent;

the preparation method of the catalyst slurry comprises the steps of weighing electrocatalyst powder and PTFE emulsion, uniformly dispersing the electrocatalyst powder and the PTFE emulsion in an alcohol-water mixed solution after high-speed mechanical stirring, wherein the mass concentration of the catalyst and PTFE in the slurry is 10-40 mg/mL; the mass ratio of the anode electrocatalyst to the PTFE is 3:1-5: 1; the mass ratio of the CO conversion catalyst to the anode electrocatalyst is 1:5 and 1: 1; the mass ratio of the cathode electrocatalyst to PTFE is 3:1-5: 1;

the preparation method of the gas diffusion electrode is to prepare catalyst slurry on the gas diffusion layer by adopting a spraying or silk-screen method; drying to remove alcohol-water solvent, and placing in a tubular furnace for heat treatment to activate the electrode;

the drying temperature is 60-80 ℃, and the drying time is 10-24 h;

the heat treatment temperature is 200-400 ℃, the atmosphere is inert, and the time is 15-60 min;

The hot pressing temperature is 100-150 ℃; the hot pressing time is not less than 3min, and the pressure is not less than 2000 Pa.

The high-temperature fuel cell membrane electrode prepared by the preparation method.

The application of the membrane electrode of the high-temperature proton membrane fuel cell based on hydrogen-poor reformed gas feed in the high-temperature fuel cell.

The high-temperature fuel cell of the membrane electrode can directly adopt reformed gas as raw material gas feed, wherein the volume content of hydrogen in the reformed gas is 20-99%, and the content of hydrogen in the reformed gas is preferably 30-50%; the reformed gas contains 0.01-10% by volume of CO, preferably 0.5-3%, and the balance of nitrogen and CO₂One or two of them.

The invention has the advantages that:

1) CO conversion catalyst is introduced into the anode gas diffusion electrode catalyst layer, so that in-situ elimination of CO in the catalyst layer can be realized;

2) the direct feeding of the hydrogen-poor reformed gas can be realized, and the discharge performance of the fuel cell is not greatly influenced.

Drawings

FIG. 1 shows a comparison of the discharge properties of the membrane electrodes prepared in example 1 and comparative example 1.

Detailed Description

The invention will be further understood by reference to the following examples.

Comparative example 1:

preparing a traditional membrane electrode: accurately weighing 100mg of Pt/C electrocatalyst powder, adding the powder into 5mL of alcohol-water mixed solution according to the amount of 20mg of catalyst per milliliter of alcohol-water mixed solution, ultrasonically dispersing in ice bath for 10min, adding 50mg of PTFE aqueous solution (60 wt%), enabling the mass ratio of PTFE to Pt/C electrocatalyst to be 3:10, and continuously ultrasonically dispersing for 10min to obtain anode catalyst slurry. All in oneThe same procedure prepared a cathode catalyst slurry containing PtCo/C and PTFE. Preparing slurry with the anode and cathode electrocatalyst, respectively, and depositing on the gas diffusion electrode by ultrasonic spray method to form anode and cathode catalyst layer, wherein the anode and cathode Pt loading amounts are 1.0mgPt/cm²And 1.5mgPt/cm²(ii) a And (3) placing the gas diffusion electrode attached with the catalytic layer in a nitrogen oven, heating to 300 ℃, and carrying out heat treatment for 60 minutes to carry out activation treatment to obtain the anode and cathode gas diffusion electrodes.

Membrane electrode preparation and single cell assembly test: respectively placing the anode gas diffusion electrode and the cathode gas diffusion electrode on two sides of a high-temperature proton membrane PBI adsorbing 450 wt%, and then overlapping the two sides to obtain a composite membrane with an effective area of 20cm²The membrane electrode is arranged between membrane electrode hot-pressing moulds, the moulds are arranged in an oil press to be preheated for 5min at the temperature of 150 ℃, hot-pressed for 10min at the temperature of 2500 pounds after being burnt, and cooled to room temperature to obtain the membrane electrode of the high-temperature proton membrane fuel cell. And testing the assembled membrane electrode into a single cell under the following test conditions: the anode was fed with 0.4 l/min of a simulated reformed gas containing 50% hydrogen, 3% CO and the balance nitrogen at 180 ℃ under normal pressure, and the cathode was fed with 0.8 l/min of air. After the battery is stably discharged, 200mA/cm²The discharge voltage was 350 mV.

Example 1:

preparing a traditional membrane electrode: accurately weighing 100mg of Pt/C electrocatalyst powder and 20mg of RuNi/C catalyst, adding the obtained product into 6ml of alcohol-water mixed solution according to the amount of 20mg of catalyst per ml of alcohol-water mixed solution, carrying out ultrasonic dispersion in ice bath for 10min, adding 50mg of PTFE aqueous solution (60 wt%) to ensure that the mass ratio of PTFE to Pt/C electrocatalyst is 3:10, and continuing to carry out ultrasonic dispersion for 10min to obtain anode catalyst slurry. A cathode catalyst slurry containing PtCo/C and PTFE was prepared in the same manner. The anode and cathode catalysts are distributed to prepare slurry and are deposited on a gas diffusion electrode by an ultrasonic spraying method to form an anode catalyst layer and a cathode catalyst layer, wherein the loading amounts of the anode Pt and the cathode Pt are respectively 1.0mgPt/cm²And 1.5mgPt/cm²RuNi/C loading of 0.2mg/cm²The gas diffusion electrode with the attached catalyst layer was placed in a nitrogen ovenHeating to 300 ℃ for 60 minutes to carry out activation treatment, thus obtaining the anode and cathode gas diffusion electrodes.

Membrane electrode preparation and single cell assembly test: respectively placing the anode gas diffusion electrode and the cathode gas diffusion electrode on two sides of a high-temperature proton membrane PBI adsorbing 450 wt%, and then overlapping the two sides to obtain a composite membrane with an effective area of 20cm²The membrane electrode is arranged between membrane electrode hot-pressing moulds, the moulds are arranged in an oil press to be preheated for 5min at the temperature of 150 ℃, hot-pressed for 10min at the temperature of 2500 pounds after being burnt, and cooled to room temperature to obtain the membrane electrode of the high-temperature proton membrane fuel cell. And testing the assembled membrane electrode into a single cell under the following test conditions: the anode was fed with 0.4 l/min of a simulated reformed gas containing 50% hydrogen, 3% CO and the balance nitrogen at 180 ℃ under normal pressure, and the cathode was fed with 0.8 l/min of air. After the battery is stably discharged, 200mA/cm²The discharge voltage was 650 mV.

Example 2:

the difference between this example and example 1 is that the CO conversion catalyst in this example is AuNi/C, and the loading in the anode catalytic layer is 1mg/cm²During the test of the cell, the content of hydrogen in the simulated reformed gas is 30%, the content of CO is 1%, and the rest is nitrogen, and after the membrane electrode prepared based on the catalyst is stably discharged, the concentration of the hydrogen is 200mA/cm²The discharge voltage was 610 mV.

Example 3:

the difference between this example and example 1 is that the CO conversion catalyst in this example is IrNi/C, and the loading in the anode catalytic layer is 2.0mg/cm²In the process of testing the battery, the content of hydrogen in the simulated reformed gas is 35 percent, the content of CO is 3 percent, and the balance is nitrogen, and after the membrane electrode prepared based on the catalyst is stably discharged, the concentration of the hydrogen is 200mA/cm²The discharge voltage is 590 mV.

Claims

1. based on hydrogen-depleted reformed gas feed high temperature proton membrane fuel cell membrane electrode, it is characterized in that:

The membrane electrode comprises an anode, a phosphoric acid-impregnated PBI membrane, and a cathode that are stacked in sequence, wherein the anode is a gas diffusion electrode with a gas diffusion layer coated with a mixed layer of hydrogen oxidation electrocatalyst and CO conversion catalyst on the surface of the gas diffusion layer facing the membrane, and the cathode is a gas diffusion electrode. A gas diffusion electrode whose surface is coated with a cathode catalyst layer on the surface of the layer facing the membrane.

2. The membrane electrode according to claim 1, characterized in that:

The anode hydrogen oxidation electrocatalyst is one or a combination of two or more of Pt/C or Pt black electrocatalysts with a mass loading of 20-60%;

The Pt loading of the anode hydrogen oxidation electrocatalyst is 0.5-2 mg/cm ² ;

The CO conversion catalyst is RuNi/C with an active metal mass loading of 20-60%, RuNi black, AuNi/C with an active metal mass loading of 20-60%, AuNi black, and an active metal mass loading of 20-60%. A combination of one or more of IrNi/C and IrNi black catalysts; the molar ratio of noble metal to Ni in the active metal is 1:1 to 3:1;

The active metal loading of the CO conversion catalyst is 0.1-0.5 mg/cm ² .

3. The membrane electrode according to claim 1, characterized in that:

Cathode catalyst is one or both of Pt/C with mass loading of 20-60%, Pt black, PtCo/C with mass loading of 20-60%, and PtNi/C with mass loading of 20-60% A combination of the above; the molar ratio of Pt to Co or Ni in the active metal is 1:1 to 3:1;

Cathode Pt loadings were 0.5-3 mg/cm ² .

4. The membrane electrode according to claim 1, characterized in that:

The gas diffusion layer is one of carbon paper, carbon cloth and conductive carbon felt coated with carbon powder and binder PTFE mixed layer on the surface facing the membrane; the carbon powder loading is 1-3 mg/cm ² , and the adhesive The agent PTFE loading is 0.1-0.3mg/cm ² ;

The phosphoric acid content in the PBI-phosphoric acid doped film is 300-500 wt%.

5. a preparation method of any one of claims 1-4 based on the hydrogen-depleted reformed gas feed high temperature proton membrane fuel cell membrane electrode, it is characterized in that:

Include the following steps:

Preparation of gas diffusion layer: coating carbon powder and binder PTFE mixed layer on the surface of carbon paper, carbon cloth and conductive carbon felt facing the membrane side, and obtaining a gas diffusion layer after drying and heat treatment;

The preparation method of the slurry of the diffusion layer is to weigh the carbon powder and the PTFE emulsion and uniformly disperse them in the alcohol-water mixed solution after high-speed mechanical stirring. 5-20mg/mL; the mass ratio range of carbon powder and PTFE in the diffusion layer is 9:1-6:4; the carbon powder loading in the diffusion layer is 1-3mg/cm ² , and the binder PTFE is loaded The amount is 0.1-0.3 mg/cm ² ;

The surface of the gas diffusion layer is coated with the catalyst slurry of the cathode and the anode, and activated by drying and heat treatment to obtain a gas diffusion electrode; the gas diffusion electrode is placed on both sides of the PBI membrane impregnated with phosphoric acid and hot pressed to obtain a membrane electrode;

The anode catalyst slurry is a dispersion of a hydroxide electrocatalyst, a CO conversion catalyst and PTFE in an alcohol-water mixed solvent; the cathode catalyst slurry is a dispersion of an oxygen reduction electrocatalyst and PTFE in an alcohol-water mixed solvent;

The preparation method of the catalyst slurry is to weigh the electrocatalyst powder and the PTFE emulsion and uniformly disperse them in the alcohol-water mixed solution after high-speed mechanical stirring. The mass concentration of the catalyst and PTFE in the slurry is 10-40 mg/mL; the anode The mass ratio of electrocatalyst to PTFE is in the range of 3:1-5:1; the mass ratio of the CO conversion catalyst to the anode electrocatalyst is 1:5 and 1:1; the mass ratio of the cathode electrocatalyst to PTFE is in the range of 3:1-5:1;

The preparation method for the gas diffusion electrode is to prepare the catalyst slurry on the gas diffusion layer by spraying or screen printing; and after drying to remove the alcohol-water solvent, place it in a tube furnace for heat treatment to activate the electrode;

The drying temperature is 60-80°C, and the time is 10-24h;

The heat treatment temperature is 200-400°C, the atmosphere is inert, and the time is 15-60min;

The phosphoric acid content in the PBI-phosphoric acid doped film is 300-500wt%;

The hot-pressing temperature is 100-150°C; the hot-pressing time is not less than 3min, and the pressure is not less than 2000Pa.

6 . The application of the membrane electrode of a high temperature proton membrane fuel cell based on hydrogen-depleted reformate gas fed in any one of claims 1 to 4 in a high temperature fuel cell. 7 .

7. According to the application of claim 6, the high temperature fuel cell using the membrane electrode can directly use the reformed gas as the raw material gas feed.

8. The application according to claim 6 or 7, wherein the hydrogen volume content in the reformed gas is 20-99%, preferably 30%-50%; the CO volume content in the reformed gas is 0.01-10%, preferably It is 0.5-3%, and the rest is one or two of nitrogen and CO ₂ .