CN111063925B

CN111063925B - Catalyst coated membrane, fuel cell and method of making

Info

Publication number: CN111063925B
Application number: CN202010046138.0A
Authority: CN
Inventors: 杨成; 樊建涛; 谢小军; 黄鹏辉; 张立; 徐娇艳; 黄衡恢
Original assignee: Shenzhen General Hydrogen Energy Technology Co ltd
Current assignee: Shenzhen General Hydrogen Energy Technology Co ltd
Priority date: 2019-08-28
Filing date: 2020-01-16
Publication date: 2020-12-15
Anticipated expiration: 2040-01-16
Also published as: CN110444791A; CN111063925A

Abstract

The invention discloses a catalyst coating film, a fuel cell and a preparation method, wherein the catalyst coating film comprises the following components: a proton exchange membrane; and the catalytic layers are formed on two opposite sides of the proton exchange membrane, and the surfaces of the catalytic layers are provided with three-dimensional microstructures. In this way, the invention can provide technical support for obtaining the membrane electrode and the fuel cell which simultaneously give consideration to water management, reduce mass transfer impedance and improve the utilization efficiency of the catalyst.

Description

Catalyst coated membrane, fuel cell and method of making

Technical Field

The invention relates to the technical field of batteries, in particular to a catalyst coating membrane, a fuel battery and a preparation method.

Background

A fuel cell is an electrochemical cell whose main principle is to convert chemical energy in a fuel and an oxidant directly into electrical energy through an oxidation-reduction reaction. The proton exchange membrane fuel cell, as an important branch in the field of fuel cells, has the general characteristics of fuel cells, and also has the outstanding advantages of high starting speed at room temperature, small volume, no electrolyte loss, easy water drainage, long service life, high specific power and specific energy and the like.

The membrane electrode is the core component of the proton exchange membrane fuel cell. The Catalyst layer is combined on the proton exchange Membrane to prepare a Catalyst Coated Membrane (CCM), and then the CCM and the gas diffusion layer are bonded together to prepare a Membrane electrode. There are two current methods for CCM production: one is to coat the catalyst directly on the proton exchange membrane, and the method has the problems that the proton exchange membrane easily absorbs the solvent in the catalyst, swells and deforms, the uniformity of the CCM structure is greatly influenced, and the structure of the catalyst layer is easy to crack. The other method is to coat the catalyst slurry on an inert substrate to form a catalyst layer, and then transfer the catalyst layer to a proton exchange membrane in a high-temperature hot-pressing mode.

Although the preparation process of the membrane electrode is improved all the time, the performance of the fuel cell is also improved, the membrane electrode cannot simultaneously give consideration to water management, mass transfer impedance reduction and catalyst utilization efficiency improvement.

Disclosure of Invention

The invention mainly solves the technical problem of providing a catalyst coating membrane, a fuel cell and a preparation method of the catalyst coating membrane, and can provide technical support for obtaining a membrane electrode and a fuel cell which simultaneously give consideration to water management, reduce mass transfer impedance and improve the utilization efficiency of a catalyst.

In order to solve the technical problems, the invention adopts a technical scheme that: providing a catalyst coated membrane comprising: a proton exchange membrane; the catalytic layers are formed on two opposite sides of the proton exchange membrane, and the surfaces of the catalytic layers are provided with three-dimensional microstructures; wherein the catalytic layer is prepared by a transfer method; the transfer printing basement membrane has indentations with different shapes; the indentation shape comprises at least one of a strip shape, a circular ring shape, a grid shape, a snake shape and a mountain peak shape; the length range of the indentation is 1-1000 um; the width range of the indentation is 1-1000 um; the depth range of the indentation is 0.1-10 um.

Wherein the surface of the catalytic layer is provided with a flow channel; the shape of the flow channel comprises at least one of a strip shape, a circular ring shape, a grid shape, a snake shape and a mountain peak shape; the length range of the flow channel is 1-1000 um; the width range of the flow channel is 1-1000 um; the depth range of the flow channel is 0.1-10 um.

In order to solve the technical problem, the invention adopts another technical scheme that: there is provided a fuel cell comprising a membrane electrode comprising a catalyst coated membrane as described in any one of the above.

In order to solve the technical problem, the invention adopts another technical scheme that: there is provided a method for producing a catalyst-coated membrane, comprising: providing a proton exchange membrane; forming a catalyst layer with a three-dimensional microstructure on the surface on two opposite sides of the proton exchange membrane;

wherein, the catalytic layer with three-dimensional microstructure on the surface is formed on two opposite sides of the proton exchange membrane, and the catalytic layer comprises: forming catalyst layers with three-dimensional microstructures on the surfaces on two opposite sides of the proton exchange membrane by a transfer printing method;

the method for forming the catalyst layer with the three-dimensional microstructure on the surface on two opposite sides of the proton exchange membrane by using a transfer printing method comprises the following steps: providing a transfer substrate film with indentations of different shapes; providing a catalyst slurry; coating the catalyst slurry on the transfer printing base film with the indentations of different shapes to form a catalyst layer; transferring the catalyst layer to upper and lower sides of the proton exchange membrane to form the catalyst coating membrane.

Wherein the providing a proton exchange membrane comprises: respectively utilizing a hydrogen peroxide solution and a sulfuric acid solution to pretreat the proton exchange membrane to obtain the pretreated proton exchange membrane.

Wherein the providing of the transfer substrate film having indentations of different shapes comprises: carrying out indentation treatment on the transfer printing base film by utilizing dies with different shapes to obtain the transfer printing base film with indentations with different shapes; wherein, the indentation shape comprises at least one of a strip shape, a circular ring shape, a grid shape, a snake shape and a mountain peak shape; the length range of the indentation is 1-1000 um; the width range of the indentation is 1-1000 um; the depth range of the indentation is 0.1-10 um; wherein the providing a catalyst slurry comprises: uniformly mixing a catalyst, a solvent and a perfluorinated sulfonic acid polymer solution to obtain catalyst slurry;

wherein the catalyst comprises platinum on carbon; the solvent comprises water and isopropanol; the mass ratio of the carbon-supported platinum to the perfluorinated sulfonic acid polymer is (1-5) to (3-1); the mass ratio of the water to the isopropanol ranges from (1-10) to (10-1); the catalyst slurry has a solids content in the range of 10-30%;

wherein the coating of the catalyst paste on the transfer substrate film having indentations of different shapes to form a catalytic layer comprises: coating the catalyst slurry on the transfer printing base film with the indentations of different shapes, and drying in an environment with a first preset temperature range to form a catalyst layer; the first predetermined temperature range is 60-80 ℃.

Wherein, the catalyst layer with three-dimensional microstructure on the surface is formed on two opposite sides of the proton exchange membrane by using a transfer printing method, and the catalyst layer comprises: providing a transfer printing substrate film and providing catalyst slurry; coating the catalyst slurry on the transfer printing base film to form a catalyst layer; transferring the catalyst layer to the upper side and the lower side of the proton exchange membrane to form a catalyst coating membrane without a three-dimensional microstructure; and carrying out indentation treatment on the surface of the catalytic layer of the catalyst coating film without the three-dimensional microstructure by using the base film with the three-dimensional microstructure to form the catalyst coating film.

The invention has the beneficial effects that: different from the situation of the prior art, the catalyst coating film of the invention has a three-dimensional microstructure on the surface of the catalyst layer formed on two opposite sides of the proton exchange membrane, on one hand, the catalyst coating film can keep the original advantages, can reduce mass transfer impedance and improve the utilization efficiency of the catalyst; on the other hand, the surface of the catalyst layer is provided with three-dimensional microstructures, which is beneficial to discharging water, increasing the three-phase interfaces of reaction gas, active catalyst and ion-conducting polymer, and further reducing mass transfer impedance.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts. Wherein:

FIG. 1 is a schematic structural view of one embodiment of a catalyst coated membrane of the present invention;

FIG. 2 is a schematic structural view of one embodiment of a catalytic layer in the catalyst coated membrane of the present invention;

FIG. 3 is a schematic structural view of another embodiment of a catalytic layer in the catalyst coated membrane of the present invention;

FIG. 4 is a schematic structural view of yet another embodiment of a catalytic layer in a catalyst coated membrane of the present invention;

FIG. 5 is a schematic structural view of yet another embodiment of a catalytic layer in a catalyst coated membrane of the present invention;

FIG. 6 is a schematic structural view of yet another embodiment of a catalytic layer in a catalyst coated membrane of the present invention;

FIG. 7 is a schematic flow chart of an embodiment of a method of making a catalyst coated membrane of the present invention;

FIG. 8 is a schematic flow diagram of another embodiment of a method of making a catalyst coated membrane of the present invention;

FIG. 9 is a schematic flow chart of yet another embodiment of a method of making a catalyst coated membrane of the present invention;

FIG. 10 is a schematic surface electron microscope view of a catalytic layer in a catalyst coated membrane made according to one embodiment of the present invention;

FIG. 11 is a schematic surface electron microscope view of a catalytic layer in a catalyst coated membrane made according to another embodiment of the present invention;

FIG. 12 is a schematic surface electron microscope view of a catalytic layer in a catalyst coated membrane made in accordance with yet another embodiment of the present invention;

FIG. 13 is a schematic surface electron microscope view of a catalytic layer in the catalyst coated film obtained in the comparative example;

FIG. 14 is a schematic polarization curve of membrane electrodes prepared from the catalyst coated membranes of FIGS. 10-13 applied to fuel cells for performance testing;

fig. 15 is a schematic diagram of performance testing of membrane electrodes prepared from the catalyst coated membranes of fig. 10-13 applied to a fuel cell with ac impedance testing at a current density of 1000 milliamps per square centimeter.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Prior to describing the present invention in detail, a description will be given of a state of the art related to the present invention.

A fuel cell is an electrochemical cell whose main principle is to convert chemical energy in a fuel and an oxidant directly into electrical energy through an oxidation-reduction reaction. Proton Exchange Membrane Fuel cells (PEMFCs, Proton Exchange Membrane Fuel cells) are an important branch of the Fuel Cell field, and besides having general characteristics of Fuel cells such as high energy conversion efficiency and environmental friendliness, they also have the outstanding advantages of fast starting speed at room temperature, small volume, no electrolyte loss, easy water discharge, long service life, high specific power and specific energy, and the like. The method is not only suitable for the construction of a distributed power station, but also suitable for mobile power supply. It is a novel military and civil portable power source.

A Membrane Electrode (MEA) is a core component of a proton exchange Membrane fuel cell, is a place where the fuel cell performs an oxidation-reduction reaction, and mainly comprises a perfluorosulfonic acid proton exchange Membrane, a catalyst, a gas diffusion layer, and a sealing material. The structural design and the preparation process proposal of the MEA, which is used as the basic unit of the electrochemical reaction of the fuel cell, need to take the basic principle and the characteristics of the electrochemical reaction of the fuel cell as the theoretical basis and take comprehensive consideration in combination with the actual working conditions. The structural design and preparation process technology of the MEA are key technologies of fuel cell research, and determine the working performance of the fuel cell. Therefore, the preparation of a high performance membrane electrode is crucial to the development of proton exchange membrane fuel cells.

The preparation methods commonly used for the membrane electrode at present mainly comprise the following methods. The traditional method is to coat a catalyst on a gas diffusion layer to prepare a gas diffusion layer electrode, and then the gas diffusion layer electrode and a proton exchange membrane are pressed together by a high-temperature hot-pressing method to prepare a membrane electrode. In the membrane electrode manufacturing method, active material particles in the catalyst layer are easily pressed into the pore channels of the microporous layer in the gas diffusion layer under high pressure to block the pore channels of the gas diffusion layer, thereby greatly increasing the mass transfer resistance and reducing the utilization efficiency of the catalyst. Meanwhile, because the proton exchange membrane and the gas diffusion layer are pressed together through high-temperature hot pressing, the contact between the proton exchange membrane and the catalyst layer is not very tight, and the contact resistance of the fuel cell is relatively high.

In order to improve the performance of the Membrane electrode of the proton exchange Membrane fuel cell, a Catalyst-Coated Membrane (CCM) prepared by bonding a Catalyst layer on a proton exchange Membrane was developed, and then the CCM and a gas diffusion layer were bonded together to prepare a Membrane electrode. The membrane electrode prepared by CCM can effectively protect the original pore structure of the gas diffusion layer, effectively improve the transmission of reaction gas and greatly increase the utilization efficiency of the catalyst. The membrane electrode prepared by CCM is developed into two preparation modes, one mode is that the catalyst is directly coated on a proton exchange membrane to prepare the CCM, and the proton exchange membrane is easy to absorb the solvent in the catalyst to swell and further deform, so that the uniformity of the structure of the prepared CCM is greatly influenced, and the structure of the catalyst layer is easy to crack. The other CCM preparation method is to coat the catalyst slurry on an inert substrate to form a catalyst layer, and then transfer the catalyst layer to the proton exchange membrane in a high-temperature hot-pressing mode.

Although the manufacturing process of the membrane electrode is continuously improved and the performance of the fuel cell is also improved, the structure of the membrane electrode has a great influence on the performance of the fuel cell. In the catalyst layer of the gas reaction site in the proton exchange membrane fuel cell, the three-phase interface formed by the reaction gas, the active catalyst and the ion-conducting polymer is mainly determined by the internal microstructure of the catalyst layer in the membrane electrode, and the three-phase interface plays a role in determining the performance of the proton exchange membrane fuel cell. In addition, cathode water management in proton exchange membrane fuel cells has a large impact on the mass transfer impedance of the fuel cell in the case of high current power generation. If the water accumulated on the cathode can not be discharged in time, the catalytic layer can be flooded by water, so that the three-phase interface is greatly reduced, the active area of the catalyst is reduced, and the performance of the fuel cell is greatly reduced.

The catalyst coating film has a three-dimensional microstructure on the surfaces of the catalyst layers formed on the two opposite sides of the proton exchange membrane, so that on one hand, the catalyst coating film can keep the original advantages, the mass transfer impedance can be reduced, and the utilization efficiency of the catalyst can be improved; on the other hand, the surface of the catalyst layer is provided with three-dimensional microstructures, which is beneficial to discharging water, increasing the three-phase interfaces of reaction gas, active catalyst and ion-conducting polymer, and further reducing mass transfer impedance.

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

Referring to fig. 1, fig. 1 is a schematic view of the structure of one embodiment of the catalyst coated membrane of the present invention, the catalyst coated membrane 100 comprising: a proton exchange membrane 1 and a catalytic layer 2. The catalytic layer 2 is formed on two opposite sides of the proton exchange membrane 1, and the surface of the catalytic layer 2 has a three-dimensional microstructure 21.

Proton Exchange Membrane 1 (PEM) plays a key role in cell performance. It has not only the barrier function but also the function of conducting protons. In the present embodiment, the proton exchange membrane 1 may be a conventional proton exchange membrane for a fuel cell, and is not limited thereto. For example: perfluorosulfonic acid proton exchange membranes, nafion recast membranes, non-fluoropolymer proton exchange membranes, novel composite proton exchange membranes, and the like.

The catalyst layer 2 is not only a place for electrochemical reaction, but also provides a transport channel for protons, electrons, reaction gas and water, and the structure thereof has a great influence on the cost and performance of the fuel cell. In this embodiment, the catalyst layers 2 are formed on two opposite sides of the proton exchange membrane 1 and belong to a CCM structure, so the catalyst coated membrane CCM of this embodiment has its own advantages, i.e., can effectively protect the original pore structure of the gas diffusion layer and effectively improve the transmission of the reaction gas; the proton exchange membrane 1 is closely contacted with the catalyst layer 2, so that the mass transfer impedance can be reduced, and the utilization efficiency of the catalyst can be greatly improved.

Meanwhile, the catalytic layer 2 of the present embodiment has a specific structure, that is, the surface of the catalytic layer 2 has a three-dimensional microstructure 21. The three-dimensional microstructure 21 refers to a non-planar and tiny three-dimensional structure, and it should be noted that some three-dimensional microstructures 21 can be seen by naked eyes, some can not be seen by naked eyes, and some can be seen by means of a magnifying glass, a microscope and the like. The structure can be beneficial to discharging water, increases the three-phase interfaces of reaction gas, active catalyst and ion-conducting polymer, further reduces mass transfer impedance, and meanwhile, the three-dimensional microstructures can also increase the specific surface area of the catalyst, thereby being beneficial to fully contacting the reaction gas with the catalyst, further increasing the active area of the catalyst and further improving the utilization efficiency of the catalyst. In this embodiment, the specific structure of the three-dimensional microstructure 21 is not limited, and the manner of forming the three-dimensional microstructure 21 is not limited.

In one embodiment, the surface of the catalytic layer 2 has a flow channel; the flow channel has a simpler structure, and the flow channel can be prepared on the catalyst layer 2 more simply. Wherein, the shape of the flow channel comprises at least one of a strip shape (as shown in fig. 2), a grid shape (as shown in fig. 3), a circular ring shape (as shown in fig. 4), a snake shape (as shown in fig. 5) and a peak shape (as shown in fig. 6); the length of the flow channel ranges from 1 to 1000um (micrometers), for example: 1um, 10um, 50um, 100um, 400um, 700um, 1000um, etc.; the width of the flow channel ranges from 1 to 1000um, for example: 1um, 10um, 50um, 100um, 400um, 700um, 1000um, etc.; the depth of the flow channel ranges from 0.1 to 10um, for example: 0.1um, 0.5um, 1um, 5um, 10um, and so forth.

Wherein the catalytic layer 2 is prepared by a transfer method; the catalyst layer 2 of the catalyst coated membrane of the present example was prepared by the transfer method, and the catalyst layer 2 was not only thin and the amount of catalyst used could be reduced, but also the influence of the solvent on the proton exchange membrane 1 could be avoided.

Specifically, the transfer base film used in the transfer method has indentations of different shapes, and functions to form a three-dimensional microstructure 21 on the surface of the catalytic layer; the indentation shape comprises at least one of a strip shape, a circular ring shape, a grid shape, a snake shape, a mountain peak shape and the like; the length of the indentations ranges from 1 to 1000um, for example: 1um, 10um, 50um, 100um, 400um, 700um, 1000um, etc.; the width of the indentations ranges from 1 to 1000um, for example: 1um, 10um, 50um, 100um, 400um, 700um, 1000um, etc.; the depth of the indentations ranges from 0.1 to 10um, for example: 0.1um, 0.5um, 1um, 5um, 10um, and so forth.

The invention also provides a fuel cell comprising a membrane electrode comprising a catalyst coated membrane as defined in any one of the preceding claims. For a detailed description of the catalyst-coated membrane, reference is made to the above description, which is not repeated herein.

Referring to fig. 7, fig. 7 is a schematic flow chart of an embodiment of the preparation method of the catalyst coated membrane of the present invention, it should be noted that the preparation method of this embodiment can prepare the above-mentioned catalyst coated membrane, and for the detailed description of the catalyst coated membrane, refer to the above-mentioned contents, and will not be described in detail herein. The method comprises the following steps:

step S101: a proton exchange membrane is provided.

Step S102: and catalyst layers with three-dimensional microstructures on the surfaces are formed on two opposite sides of the proton exchange membrane.

The method of forming the catalytic layer with three-dimensional microstructure on the surface on the two opposite sides of the proton exchange membrane includes but is not limited to: after catalyst layers are formed on two opposite sides of the proton exchange membrane, a three-dimensional microstructure is formed on the surfaces of the catalyst layers in an additional processing mode; or, a catalyst layer with a three-dimensional microstructure is formed first and then transferred to two opposite sides of the proton exchange membrane; and so on.

The catalyst coating film prepared by the embodiment of the invention has a three-dimensional microstructure on the surface of the catalyst layer formed on two opposite sides of the proton exchange membrane, so that on one hand, the catalyst coating film can keep the original advantages, the mass transfer impedance can be reduced, and the utilization efficiency of the catalyst can be improved; on the other hand, the surface of the catalyst layer is provided with three-dimensional microstructures, which is beneficial to discharging water, increasing the three-phase interfaces of reaction gas, active catalyst and ion-conducting polymer, and further reducing mass transfer impedance.

Wherein, the surface of the catalytic layer is provided with a flow channel; the shape of the flow channel comprises at least one of a strip shape, a circular ring shape, a grid shape, a snake shape, a mountain peak shape and the like; the length range of the flow channel is 1-1000 um; the width range of the flow channel is 1-1000 um; the depth of the flow channel ranges from 0.1 to 10 um.

In an embodiment, step S101, providing a proton exchange membrane may include:

respectively utilizing a hydrogen peroxide solution and a sulfuric acid solution to pretreat the proton exchange membrane to obtain the pretreated proton exchange membrane.

The purpose of the pretreatment is to remove organic and inorganic impurities from the proton exchange membrane. The hydrogen peroxide solution can remove organic impurities, and the sulfuric acid solution can remove inorganic metal ions. In general, the hydrogen peroxide solution is usually used in a concentration of 3 to 5%, and the sulfuric acid solution is usually in a concentration of 0.5 mol/L.

For example, in one practical application, the pretreatment process for the proton exchange membrane is: soaking a proton exchange membrane in 3-5% hydrogen peroxide solution, placing the proton exchange membrane in an environment of 60-120 ℃ for 3-6h, then washing the proton exchange membrane for 3-5 times by using deionized water, soaking the proton exchange membrane in 0.5mol/L sulfuric acid, placing the proton exchange membrane in a constant temperature environment of 50-90 ℃ for 1-3h, then washing the proton exchange membrane for 3-5 times by using deionized water, and finally placing the proton exchange membrane in a vacuum drying oven for drying for 24h at 60 ℃.

In an embodiment, in step S102, forming a catalytic layer with a three-dimensional microstructure on the surface on two opposite sides of the proton exchange membrane specifically includes: and forming a catalytic layer with a three-dimensional microstructure on the surface on two opposite sides of the proton exchange membrane by using a transfer printing method.

The transfer printing method is that catalyst slurry is coated on an inert transfer printing basement membrane to form a catalyst layer, then the catalyst layer is transferred to a proton exchange membrane in a high-temperature hot pressing mode, and the membrane electrode prepared through transfer printing is thin in catalyst layer, so that the use amount of catalyst can be reduced, and the influence of solvent on the proton exchange membrane can be avoided.

Specifically, referring to fig. 8, forming a catalytic layer having a three-dimensional microstructure on the surface thereof on both opposite sides of a proton exchange membrane by a transfer method may include:

step S201: a transfer substrate film having indentations of different shapes is provided, and a catalyst paste is provided.

Step S202: and coating the catalyst slurry on a transfer printing base film with indentations of different shapes to form a catalytic layer.

Step S203: the catalyst layer is transferred to the upper and lower sides of the proton exchange membrane to form a catalyst coating membrane.

In the embodiment, indentations with different shapes are formed on the transfer base film in advance, and after the catalyst slurry is coated on the transfer base film, the indentations with different shapes are transferred to the catalyst layer and further transferred to the upper side and the lower side of the proton exchange membrane during transfer. The surface of the prepared catalyst layer has a specific three-dimensional microstructure, the three-dimensional microstructure on the surface of the catalyst layer can be beneficial to water management, the performance of the fuel cell is greatly improved, the utilization efficiency of the catalyst is improved, and the using amount of the catalyst can be reduced, so that the cost of the fuel cell is reduced. In addition, the preparation process is simple and controllable, and industrial large-scale production can be easily realized.

Specifically, in step S201, providing a transfer substrate film having indentations of different shapes may specifically include: and carrying out indentation treatment on the transfer printing base film by using the molds with different shapes to obtain the transfer printing base film with indentations with different shapes.

Wherein, the indentation shape comprises at least one of a strip shape, a circular ring shape, a grid shape, a snake shape, a mountain peak shape and the like; the length range of the indentation is 1-1000 um; the width range of the indentation is 1-1000 um; the depth of the indentation ranges from 0.1 to 10 um.

The surface three-dimensional microstructure of the catalytic layer can be properly changed according to the actual operation condition of the fuel cell, correspondingly, the shape of the indentation can be properly changed, and can be different, and the size of the indentation can be easily adjusted.

In step S201, providing a catalyst slurry may include: and uniformly mixing the catalyst, the solvent and the perfluorinated sulfonic acid polymer solution to obtain catalyst slurry.

Wherein the catalyst comprises platinum on carbon; the solvent comprises water and isopropanol; the mass ratio of platinum on carbon to perfluorosulfonic acid polymer ranges from (1-5) to (3-1), for example: 1:3, 3:2, 5:1, etc.; the mass ratio of water to isopropyl alcohol ranges from (1-10) to (10-1), for example: 1:10, 1:1, 10:1, etc.; the catalyst slurry has a solids content in the range of 10-30%, for example: 10%, 20%, 30%, etc.

In step S202, coating the catalyst slurry on the transfer substrate film having indentations of different shapes to form the catalyst layer may include: coating the catalyst slurry on a transfer printing base film with indentations of different shapes, and drying in an environment with a first preset temperature range to form a catalyst layer; the first predetermined temperature range is 60-80 ℃, for example: 60 ℃, 70 ℃, 80 ℃, etc.

Referring to fig. 9, in another embodiment, forming a catalytic layer with a three-dimensional microstructure on two opposite sides of a proton exchange membrane by a transfer method may further include:

step S301: providing a transfer substrate film and providing a catalyst slurry.

Step S302: and coating the catalyst slurry on the transfer substrate film to form the catalytic layer.

Step S303: and transferring the catalyst layer to the upper side and the lower side of the proton exchange membrane to form the catalyst coating membrane without a three-dimensional microstructure.

Step S304: and (3) carrying out indentation treatment on the surface of the catalyst layer of the catalyst coating film without the three-dimensional microstructure by using the base film with the three-dimensional microstructure to form the catalyst coating film.

In the present embodiment, the transfer base film is a normal, impression-free transfer base film. In this embodiment, a common and normal catalyst coating film without a three-dimensional microstructure is formed according to the existing transfer printing technology, and then the surface of the catalyst layer of the catalyst coating film without a three-dimensional microstructure is subjected to indentation treatment by using the base film with a three-dimensional microstructure, so as to obtain the catalyst coating film of this embodiment.

The preparation method of the catalyst and the catalyst prepared by the method of the present invention will be described below with reference to specific examples.

Example 1:

the first step is as follows: pretreatment of a proton exchange membrane and preparation of catalyst slurry, which comprises the following steps:

(1) pretreatment of the proton exchange membrane: soaking a 7.1 cm-7.1 cm proton exchange membrane in a 5% hydrogen peroxide solution, placing the membrane in an environment at 70 ℃ for 5 hours, then washing the membrane with deionized water for 3 times, soaking the membrane in 0.5mol/L sulfuric acid, placing the membrane in a constant temperature environment at 60 ℃ for 1 hour, then washing the membrane with deionized water for 3 times, and finally placing the membrane in a vacuum drying oven for drying at 60 ℃ for 24 hours.

(2) Preparation of catalyst slurry: fully and uniformly mixing a certain mass of Pt/C catalyst, deionized water, isopropanol and Nafion solution. Wherein the mass ratio of the Pt/C catalyst to the nafion is 2: 1. Deionized water: the mass ratio of the isopropanol is 5: 3. Wherein the catalyst slurry has a solids content of 25%.

In example 1 above, the mass of the Pt/C catalyst was 1.2g, the mass of the 20% nafion solution was 3g, the mass of deionized water was 2.17g, and the mass of isopropyl alcohol was 0.83 g.

The second step is that: the membrane electrode preparation comprises the following steps:

for the treatment of transfer substrate films for CCM, an inert, smooth-surfaced Polytetrafluoroethylene (PTFE) substrate film was scored with a mold having a different serpentine shape. The size of the indentation shape can be 800um in length, 4um in width and 2um in depth.

Coating the catalyst slurry on a transfer printing basement membrane subjected to indentation treatment, drying the transfer printing basement membrane at 60 ℃, then transferring the catalyst layer to the upper surface and the lower surface of a proton exchange membrane through high-temperature hot pressing to prepare CCM, and finally attaching the gas diffusion layers to the upper surface and the lower surface of the CCM to prepare the membrane-forming electrode. A schematic surface electron microscope of the catalytic layer prepared by indentation treatment of the transfer base film is shown in fig. 10.

Example 2:

In example 2 above, the mass of the Pt/C catalyst was 1.2g, the mass of the 20% nafion solution was 3g, the mass of deionized water was 2.17g, and the mass of isopropyl alcohol was 0.83 g.

for the treatment of a transfer base film for CCM production, a polytetrafluoroethylene base film having a smooth inert surface was subjected to indentation treatment using a mold having a strip shape. The size of the indentation shape can be 1000um in length, 1um in width and 1um in depth.

Coating the catalyst slurry on a transfer printing basement membrane subjected to indentation treatment, drying the transfer printing basement membrane at 60 ℃, then transferring the catalyst layer to the upper surface and the lower surface of a proton exchange membrane through high-temperature hot pressing to prepare CCM, and finally attaching the gas diffusion layers to the upper surface and the lower surface of the CCM to prepare the membrane-forming electrode. A schematic surface electron microscope of the catalytic layer prepared by indentation treatment of the transfer base film is shown in fig. 11.

Example 3:

In example 3 above, the mass of the Pt/C catalyst was 1.2g, the mass of the 20% nafion solution was 3g, the mass of deionized water was 2.17g, and the mass of isopropyl alcohol was 0.83 g.

for the treatment of the transfer base film for CCM production, a polytetrafluoroethylene base film having a smooth inert surface was subjected to indentation treatment using a mold having a grid shape. The size of the indentation shape can be 1000um in length, 2um in width and 1um in depth.

Coating the catalyst slurry on a transfer printing basement membrane subjected to indentation treatment, drying the transfer printing basement membrane at 60 ℃, then transferring the catalyst layer to the upper surface and the lower surface of a proton exchange membrane through high-temperature hot pressing to prepare CCM, and finally attaching the gas diffusion layers to the upper surface and the lower surface of the CCM to prepare the membrane-forming electrode. Fig. 12 is a schematic surface electron microscope view of the catalytic layer prepared by subjecting the transfer base film to indentation treatment.

Comparative example:

the first step is as follows: the proton exchange membrane treatment and the preparation of the catalyst slurry comprise the following steps:

In the above comparative example, the mass of the Pt/C catalyst was 1.2g, the mass of the 20% nafion solution was 3g, the mass of deionized water was 2.17g, and the mass of isopropyl alcohol was 0.83 g.

coating the catalyst slurry on a PTFE (polytetrafluoroethylene) base membrane with a smooth surface, drying the PTFE base membrane at 60 ℃, transferring the catalyst layer to the upper surface and the lower surface of a proton exchange membrane through high-temperature hot pressing to prepare CCM (continuous current mode membrane), and finally attaching the gas diffusion layers to the upper surface and the lower surface of the CCM to prepare a membrane-forming electrode. Fig. 13 is a schematic surface electron microscope view of the catalytic layer prepared by subjecting the transfer base film to no indentation treatment.

The membrane electrodes of examples 1 to 3 and comparative example were assembled into fuel cells respectively and subjected to a performance test, the polarization curve test being shown in fig. 14; the ac impedance test at a current density of 1000 ma/cm is shown in fig. 15, with test conditions: the temperature is 70 ℃, the humidity is 100%, the flow rate of hydrogen and air is 1.3/2.0 according to the metering ratio, the back pressure of a hydrogen end is 0.2MPa, and the back pressure of an air end is 0.2 MPa.

From example 1 of fig. 10 to example 3 of fig. 12, a comparison with fig. 13 shows: and performing indentation treatment on the transfer printing base film to prepare a catalytic layer with a specific three-dimensional microstructure on the surface. As can be seen from fig. 14: the voltage of inventive examples 1 to 3 was higher and the power density was higher than that of comparative example at the same current density, while the maximum power density of inventive examples 1 to 3 was much higher than that of comparative example, indicating that the performance of inventive fuel cells of examples 1 to 3 was better than that of comparative fuel cells. As can be seen from fig. 15: the charge transfer impedance and the mass transfer resistance of the membrane electrode in the embodiments 1 to 3 of the present invention are smaller than those of the comparative example, which shows that the catalytic layer in the serpentine structure, the strip structure, and the grid structure in the embodiments 1 to 3 can not only increase the specific surface area of the catalytic layer and improve the utilization rate of the catalyst, but also facilitate the removal of water from the fuel cell and improve the gas permeability.

In general, the three-dimensional microstructure on the surface of the catalytic layer in the embodiment of the invention can be beneficial to water management, greatly improve the performance of the fuel cell, improve the utilization efficiency of the catalyst, and reduce the dosage of the catalyst, thereby realizing the reduction of the cost of the fuel cell.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A catalyst coated membrane, comprising:

a proton exchange membrane;

the catalytic layers are formed on two opposite sides of the proton exchange membrane, and the surfaces of the catalytic layers are provided with three-dimensional microstructures;

the catalytic layer is prepared by a transfer method; the transfer printing basement membrane has indentations with different shapes; the indentation shape comprises at least one of a strip shape, a circular ring shape, a grid shape, a snake shape and a mountain peak shape; the length range of the indentation is 1-1000 um; the width range of the indentation is 1-1000 um; the depth range of the indentation is 0.1-10 um.

2. The catalyst coated membrane of claim 1, wherein the surface of the catalytic layer has flow channels; the shape of the flow channel comprises at least one of a strip shape, a circular ring shape, a grid shape, a snake shape and a mountain peak shape; the length range of the flow channel is 1-1000 um; the width range of the flow channel is 1-1000 um; the depth range of the flow channel is 0.1-10 um.

3. A fuel cell comprising a membrane electrode comprising a catalyst coated membrane according to any one of claims 1-2.

4. A method of making a catalyst coated membrane, comprising:

providing a proton exchange membrane;

forming a catalyst layer with a three-dimensional microstructure on the surface on two opposite sides of the proton exchange membrane;

wherein, the catalytic layer with three-dimensional microstructure on the surface is formed on two opposite sides of the proton exchange membrane, and the catalytic layer comprises:

forming catalyst layers with three-dimensional microstructures on the surfaces on two opposite sides of the proton exchange membrane by a transfer printing method;

the method for forming the catalyst layer with the three-dimensional microstructure on the surface on two opposite sides of the proton exchange membrane by using a transfer printing method comprises the following steps:

providing a transfer printing substrate film with indentations of different shapes, and providing catalyst slurry;

coating the catalyst slurry on the transfer printing base film with the indentations of different shapes to form a catalyst layer;

transferring the catalyst layer to upper and lower sides of the proton exchange membrane to form the catalyst coating membrane.

5. The method of claim 4, wherein the surface of the catalytic layer has flow channels; the shape of the flow channel comprises at least one of a strip shape, a circular ring shape, a grid shape, a snake shape and a mountain peak shape; the length range of the flow channel is 1-1000 um; the width range of the flow channel is 1-1000 um; the depth range of the flow channel is 0.1-10 um.

6. The method of claim 4, wherein the providing a proton exchange membrane comprises:

7. The method according to claim 4, wherein the providing of the transfer substrate film with indentations of different shapes comprises:

carrying out indentation treatment on the transfer printing base film by utilizing dies with different shapes to obtain the transfer printing base film with indentations with different shapes;

wherein, the indentation shape comprises at least one of a strip shape, a circular ring shape, a grid shape, a snake shape and a mountain peak shape; the length range of the indentation is 1-1000 um; the width range of the indentation is 1-1000 um; the depth range of the indentation is 0.1-10 um;

wherein the providing a catalyst slurry comprises:

uniformly mixing a catalyst, a solvent and a perfluorinated sulfonic acid polymer solution to obtain catalyst slurry;

wherein the coating of the catalyst paste on the transfer substrate film having indentations of different shapes to form a catalytic layer comprises:

coating the catalyst slurry on the transfer printing base film with the indentations of different shapes, and drying in an environment with a first preset temperature range to form a catalyst layer; the first predetermined temperature range is 60-80 ℃.

8. The method according to claim 6, wherein the forming of the catalytic layer with three-dimensional microstructure on the surface of the catalytic layer on two opposite sides of the proton exchange membrane by transfer method comprises:

providing a transfer printing substrate film and providing catalyst slurry;

coating the catalyst slurry on the transfer printing base film to form a catalyst layer;

transferring the catalyst layer to the upper side and the lower side of the proton exchange membrane to form a catalyst coating membrane without a three-dimensional microstructure;

and carrying out indentation treatment on the surface of the catalytic layer of the catalyst coating film without the three-dimensional microstructure by using the base film with the three-dimensional microstructure to form the catalyst coating film.