CN-121983589-A - Membrane electrode based on direct coating process and preparation method and application thereof

Abstract

The invention provides a membrane electrode based on a direct coating process, and a preparation method and application thereof, and belongs to the technical field of fuel cells. The invention directly coats the cathode or anode catalyst slurry on one side of the proton exchange membrane with a temporary support substrate, then directly coats the proton exchange membrane functional layer and the catalyst slurry on the surface of the coated catalyst layer, thereby realizing the continuous construction of the proton exchange membrane and the double-side catalyst layer, and finally promotes interface fusion and structure densification through annealing treatment to obtain the complete three-in-one membrane electrode. The method completely eliminates the transfer film and the hot-pressing transfer step required in the traditional transfer printing process, simplifies the manufacturing process, reduces the material and energy consumption cost, and obviously improves the production speed. More importantly, by precisely controlling the coating sequence, the slurry formula and the drying-annealing process, the swelling and deformation of the proton exchange membrane in the wet-dry cycle process are effectively inhibited, and the membrane electrode structure is ensured to be flat and the interface is ensured to be firmly combined.

Inventors

• WANG SHANGSHANG
• WANG XIAOXING
• HUANG QIRUI

Assignees

• 常州氢龙科技有限公司

Dates

Publication Date

20260505

Application Date

20251229

Claims (10)

1. 1. The preparation method of the membrane electrode based on the direct coating process is characterized by comprising the following steps of: (1) Preparation of cathode or anode catalyst slurry: Mixing perfluorinated sulfonic acid resin and organic alcohol to obtain ionomer-alcohol mixed solution, adding the ionomer-alcohol mixed solution into the catalyst dispersion, and ball milling to obtain cathode or anode catalyst slurry; (2) Preparation of proton membrane solution: Mixing perfluorinated sulfonic acid resin, ultrapure water, organic alcohol and an additive to obtain a proton membrane solution; (3) Preparation of a membrane electrode: And (3) coating cathode or anode catalyst slurry on a substrate membrane of the proton exchange membrane, then directly coating a proton exchange membrane layer prepared based on the proton membrane solution in the step (2) and anode or cathode catalyst slurry on the substrate membrane, respectively drying the layers, and annealing to obtain the membrane electrode.
2. 2. The preparation method of claim 1, wherein in the step (1), the solid content of the cathode or anode catalyst slurry is 10-20%, the Pt content is 10-60%, the mass ratio of ultrapure water to organic alcohol is 0.45-2:1, and the mass ratio of perfluorosulfonic acid resin to catalyst I to C is 0.7-1.4:1.
3. 3. The method according to claim 2, wherein in the step (1), the organic alcohol comprises one or more of n-propanol, isopropanol and ethanol, and the catalyst comprises one of Pt/C catalyst and PtM/C catalyst.
4. 4. The preparation method of claim 1, wherein in the step (2), the mass ratio of the ultrapure water to the organic alcohol is 0.45-2:1, the solid content of the perfluorosulfonic acid resin in the proton membrane solution is 10-35%, and the dosage of the additive is 0.5-2% of the total solid content.
5. 5. The method according to claim 1, wherein in the step (2), the organic alcohol comprises one or more of n-propanol, isopropanol, and ethanol.
6. 6. The preparation method according to claim 1, wherein in the step (3), the wet thickness of the cathode catalyst slurry is 120-160 μm, the coating speed is 0.8-3.5 m/min, the wet thickness of the anode catalyst slurry is 30-40 μm, the coating speed is 0.8-3.5 m/min, and the drying temperature is 80-100 ℃.
7. 7. The preparation method of claim 1, wherein in the step (3), the proton exchange membrane comprises a first slurry layer, an intermediate reinforcing layer and a second slurry layer, wherein the wet thickness of the first slurry layer is 40-60 μm, the wet thickness of the intermediate reinforcing layer e-PTFE is 2-4 μm, the wet thickness of the second slurry layer is 20-50 μm, the coating speed is 0.8-3.5 m/min, and the drying temperature is 120-140 ℃.
8. 8. The method according to claim 7, wherein the annealing temperature is 160-200 ℃.
9. 9. A membrane electrode prepared according to the preparation method of any one of claims 1 to 8.
10. 10. Use of the membrane electrode of claim 9 in a fuel cell.

Description

Membrane electrode based on direct coating process and preparation method and application thereof Technical Field The invention relates to the technical field of fuel cells, in particular to a membrane electrode based on a direct coating process, and a preparation method and application thereof. Background The membrane electrode (Membrane Electrode Assembly, MEA) is a core component for realizing electrochemical energy conversion in a Proton Exchange Membrane Fuel Cell (PEMFC) stack, and the structure directly determines the output performance, the operation stability and the service life of the cell. As the only place where the electrochemical reaction occurs, the membrane electrode is required to efficiently conduct protons and transport electrons, and also ensure smooth diffusion of reaction gases (such as hydrogen and oxygen) and effective discharge of generated water. Therefore, the design and manufacturing process thereof have a decisive influence on the efficiency and reliability of the entire fuel cell system. The cost of the membrane electrode is about 50% or more of the total cost of the fuel cell stack, which is one of the key factors that restrict the large-scale commercial application of fuel cells. A typical membrane electrode is in a "three-in-one" (Catalyst Coated Membrane, CCM) structure, and is formed by sandwiching a proton exchange membrane (e.g., nafion membrane) between an anode catalytic layer and a cathode catalytic layer. The catalytic layer is typically composed of a noble metal catalyst (e.g., platinum or platinum alloy), a carbon support, an ionomer (e.g., perfluorosulfonic acid resin), and a suitable amount of solvent, and is attached to the proton exchange membrane surface by a precision coating process. The ideal catalytic layer should possess high catalytic activity, good proton/electron conducting network, suitable porosity and strong interfacial bonding with the membrane. In order to achieve the above-mentioned goal, the industry has developed various membrane electrode preparation technologies, mainly including the three kinds of first, double-sided transfer printing method, namely, coating cathode-anode catalyst slurry on two high-temperature resistant transfer printing substrates (such as PTFE membrane) respectively, baking and solidifying, placing a proton exchange membrane between two catalytic layers, transferring the catalytic layers from the transfer printing membrane to the proton exchange membrane through hot pressing, second, single-sided direct coating+single-sided transfer printing method, wherein the cathode catalytic layer is usually directly coated on one side of the proton exchange membrane, and the anode is bonded in a transfer printing mode, and third, double-sided direct coating method, namely, coating one catalytic layer on the proton exchange membrane with a temporary support substrate, removing the substrate, and then directly coating a second catalytic layer on the other side of the bare membrane. Although the above method has a certain feasibility in laboratory or small volume production, significantly short plates are exposed in industrial applications. Although the double-sided transfer printing method can better control the appearance of the catalytic layer, the process flow is long, multiple coating, drying, hot pressing and stripping operations are needed, and a large amount of disposable transfer printing films are used as intermediate consumable materials, so that the material cost is increased, and the production efficiency and consistency are reduced. The single-sided direct coating and transfer printing simplifies the process to a certain extent, but can not thoroughly get rid of the dependence on a transfer printing film, and can not fundamentally solve the problems of cost and environmental protection. While the double-sided direct coating method has the most cost advantage in theory, the method faces serious challenges in practical operation, namely, the proton exchange membrane is soft in texture and strong in hydrophilicity, and when a second catalytic layer is coated, irreversible swelling, curling or wrinkling is extremely easy to occur in the solvent infiltration-drying cycle process due to lack of rigid support, so that the defects of cracking, uneven thickness, interface debonding and the like of the catalytic layer are caused, and the electrochemical performance and yield of the membrane electrode are seriously affected. In addition, as fuel cells move toward higher power densities, longer lifetimes, and lower costs, higher demands are placed on membrane electrode structural uniformity, interface integrity, and mass production capabilities. The traditional process has approaching the technical limit in aspects of micron-scale coating control, membrane deformation inhibition, ionomer distribution optimization and the like. Therefore, it is important to break through the existing preparation paradigm and develop a novel one-step m