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CN-121983590-A - PEM fuel cell membrane electrode and preparation method thereof

CN121983590ACN 121983590 ACN121983590 ACN 121983590ACN-121983590-A

Abstract

The invention belongs to the technical field of fuel cells, and particularly relates to a PEM fuel cell membrane electrode and a preparation method thereof. The preparation method of the PEM fuel cell membrane electrode comprises the following steps of preparing composite hydrophilic resin and composite hydrophobic resin, preparing cathode first catalytic layer slurry by adopting the composite hydrophilic resin, controlling the spraying rate to obtain a cathode first catalytic layer with gradually changed content of the composite hydrophilic resin, preparing cathode second catalytic layer slurry by adopting the composite hydrophobic resin, controlling the spraying rate to obtain a cathode second catalytic layer with gradually changed content of the composite hydrophobic resin, performing transfer printing hot pressing on the cathode first catalytic layer, the cathode second catalytic layer, the anode catalytic layer and a proton membrane to obtain the membrane electrode, wherein the content of the composite hydrophilic resin in the cathode first catalytic layer is uniformly reduced from top to bottom along the gravity direction, and the content of the composite hydrophobic resin in the cathode second catalytic layer is uniformly increased from top to bottom along the gravity direction.

Inventors

  • WANG LINAN
  • WANG SHUNZHONG
  • CAO YALI
  • WANG ZHICHANG
  • CHEN WEI
  • NI HAIFANG
  • Cui Lirui
  • ZHAO WEI
  • ZHOU MINGZHENG

Assignees

  • 国家电投集团氢能科技发展有限公司

Dates

Publication Date
20260505
Application Date
20260120

Claims (10)

  1. 1. A method of making a PEM fuel cell membrane electrode comprising the steps of: (1) Preparing composite hydrophilic resin and composite hydrophobic resin; (2) Preparing cathode first catalytic layer slurry by adopting the composite hydrophilic resin in the step (1), spraying the slurry on a substrate, drying to form a cathode first catalytic layer, wherein the spraying flow is 0.3-3 mL/min, and the spraying rate is increased from 0.1 m/min to 1 m/min; (3) Preparing cathode second catalytic layer slurry by adopting the composite hydrophobic resin in the step (1), spraying the slurry on a substrate, drying to form a cathode second catalytic layer, wherein the spraying flow is 0.3-3 mL/min, and the spraying rate is linearly reduced from 1 m/min to 0.1 m/min; (4) Preparing anode catalytic layer slurry, spraying the slurry on a substrate, and drying to form an anode catalytic layer; (5) And carrying out transfer printing and hot pressing on the cathode first catalytic layer, the cathode second catalytic layer, the anode catalytic layer and the proton membrane to obtain a membrane electrode, wherein the content of the composite hydrophilic resin in the cathode first catalytic layer is uniformly reduced from top to bottom along the gravity direction, the cathode second catalytic layer is far away from the proton membrane, and the content of the composite hydrophobic resin in the cathode second catalytic layer is uniformly increased from top to bottom along the gravity direction.
  2. 2. The method of preparing a PEM fuel cell membrane electrode according to claim 1 wherein in said step (1), said complex hydrophilic resin comprises a resin and a hydrophilic agent, The resin is a perfluorinated sulfonic acid resin, The hydrophilic agent comprises at least one of polyvinyl alcohol, polyethylene oxide, polyethylene glycol, gas phase hydrophilic nano silicon dioxide, hydroxylated carbon nano tube or carboxylated carbon nano tube, The mass ratio of the hydrophilic agent to the resin is (1.5-3): 1.
  3. 3. The method for preparing a PEM fuel cell membrane electrode according to claim 2, wherein the method for preparing the composite hydrophilic resin comprises the steps of mixing an aqueous solution of a hydrophilic agent and an n-propanol solution of the resin, physically crosslinking for 3-4 hours at 150-200 ℃ and 700-1000 rpm in a reflux condensing device, and then sequentially performing natural cooling, filtering separation, recrystallization purification and drying treatment.
  4. 4. The method of making a PEM fuel cell membrane electrode according to claim 1 wherein in said step (1) said composite hydrophobic resin comprises a resin and a hydrophobic agent; the resin is perfluorinated sulfonic acid resin; the hydrophobizing agent comprises at least one of gas phase hydrophobic nano silicon dioxide, polytetrafluoroethylene, polyethylene propylene copolymer, perfluoroalkoxy vinyl ether copolymer or polyethylene tetrafluoroethylene copolymer; the mass ratio of the hydrophobizing agent to the resin is 1 (1.5-3).
  5. 5. The method for preparing a PEM fuel cell membrane electrode according to claim 4, wherein the preparation method of the composite hydrophobic resin comprises the steps of crushing a mixed solution of a hydrophobic agent and ethanol in a cell crusher to form a suspension, mixing the suspension, n-propanol and the resin, performing physical crosslinking in a reflux condensing device at 200-250 ℃ and 500-800 rpm for 3-4 hours, and then performing natural cooling, filtering separation, recrystallization purification and drying treatment in sequence.
  6. 6. The method for preparing the PEM fuel cell membrane electrode according to claim 1, wherein in the step (2), the preparation method of the first catalytic layer slurry comprises the steps of putting a Pt/C catalyst into a ball milling tank, adding deionized water, stirring uniformly, standing, adding n-propanol, composite hydrophilic resin and ZrO 2 ball milling beads in sequence, and carrying out ball milling treatment for 8-12 hours at a rotating speed of 400-500 r/min; The mass ratio of the Pt/C catalyst to the deionized water to the n-propanol to the composite hydrophilic resin to the ZrO 2 ball-milling beads is (0.2-0.3), 3-10, 10-40, 0.5-1.2 and 150-250.
  7. 7. The method for preparing the PEM fuel cell membrane electrode according to claim 1, wherein in the step (3), the preparation method of the second catalyst layer slurry comprises the steps of weighing Pt/C catalyst, putting the Pt/C catalyst into a ball milling tank, adding deionized water, stirring uniformly, standing, sequentially adding n-propanol, composite hydrophobic resin and ZrO 2 ball milling beads, and performing ball milling treatment for 8-12 hours at a rotating speed of 400-500 r/min; The mass ratio of the Pt/C catalyst to the deionized water to the n-propanol to the composite hydrophobic resin to the ZrO 2 ball-milling beads is (0.2-0.3), 3-10, 20-40, 0.3-0.5 and 150-250.
  8. 8. The preparation method of the PEM fuel cell membrane electrode according to claim 1, wherein in the step (4), the preparation method of the anode catalytic layer slurry comprises the steps of putting a Pt/C catalyst and IrO 2 into a ball milling tank, adding deionized water to fully wet the catalyst, stirring uniformly, standing, sequentially adding n-propanol, short-chain resin and ZrO 2 ball milling beads, and carrying out ball milling treatment for 8-12 hours at a rotating speed of 400-500 r/min, wherein the mass ratio of the Pt/C catalyst, the IrO 2 , deionized water, the n-propanol, the short-chain resin and the ZrO 2 ball milling beads is (0.2-0.3): (20×10 -6 ~40×10 -6 ): (3-10): (20-40): (0.4-0.6): (150-250); And/or in the step (4), the spraying comprises stirring the anode catalytic layer slurry for 20-30 min at a rotating speed of 200-400 r/min, transferring the slurry into an injector of a spraying machine, wherein the spraying flow is 0.3-1 mL/min, and the spraying speed is 0.1-1 m/min; And/or in the step (4), the temperature of the drying treatment is 70-90 ℃ and the time of the drying treatment is 5-8 hours.
  9. 9. The method for producing a PEM fuel cell membrane electrode according to claim 1 wherein in said step (5), said hot pressing is performed at a temperature of 155 to 175 ℃, a pressure of 20 to 40 kgf/cm 2 , and a time of 75 to 200 seconds.
  10. 10. A PEM fuel cell membrane electrode produced by the method of any one of claims 1 to 9.

Description

PEM fuel cell membrane electrode and preparation method thereof Technical Field The invention belongs to the technical field of fuel cells, and particularly relates to a PEM fuel cell membrane electrode and a preparation method thereof. Background Proton Exchange Membrane Fuel Cells (PEMFCs) are a clean, efficient power generation device that converts chemical energy directly into electrical energy. During its operation, a Membrane Electrode (MEA) is the core component of an electrochemical reaction, and water management inside it is critical. The ideal water management state is that the proton exchange membrane remains sufficiently wet to ensure high proton conductivity while the reactant gas channels are not blocked by excess liquid water to ensure smooth transfer of reactant gas to the catalytic layer. However, in actual operation, particularly under high current, high humidity conditions, a large amount of water is generated at the cathode side. Due to gravity, this liquid water naturally migrates and accumulates below the fuel cell, causing the lower half of the membrane electrode (near the ground end) to be susceptible to "flooding". Flooding can clog the pores of the porous electrode, hinder the diffusion of reactant gases (e.g., hydrogen, air/oxygen) to the catalytic layer, resulting in increased mass transfer polarization and a dramatic drop in output voltage and power density. In order to cope with the above-mentioned water management challenges, especially the problem of uneven water volume in the upper and lower parts caused by gravity, various technical solutions have been proposed in the industry. Wherein the hydrophilic or hydrophobic treatment of the catalytic layer (CCM) and the Gas Diffusion Layer (GDL) is mainly focused on to regulate the distribution and drainage of moisture. One common implementation is to coat a microporous layer with a single, uniform hydrophobicity over the gas diffusion layer substrate. This homogeneous hydrophobic layer is intended to prevent liquid water from stagnating in the channels by virtue of its hydrophobicity and to be discharged by gas purging. Another improvement is to attempt to build a gradient hydrophobic structure, i.e. progressively increasing hydrophobicity from CCM to GDL to the double-layer plate side, to create a water drainage driving force directed to the flow channels. Although the above prior art improves the water management capability of the fuel cell to some extent, there are significant limitations in solving the specific problem of maldistribution of water in the upper and lower parts of the membrane electrode due to gravity. Firstly, the upper and lower differences caused by gravity cannot be solved pertinently, and the whole membrane electrode or the gas diffusion layer is globally and uniformly modified in terms of material whether uniform hydrophobic treatment or longitudinal gradient design is carried out. This "one-shot" strategy ignores the objective fact that the gravitational field causes much more bottom water than top. Secondly, the homogeneous hydrophobic treatment may cause the upper half of the membrane electrode to be too dry in the area which is easy to dry, so that the proton exchange membrane is insufficiently wetted, the resistance is increased, the low electrical tightness is low, and for the lower half with large water accumulation, the hydrophobic capacity of the membrane electrode is insufficient to effectively discharge excessive accumulated water, and the membrane electrode is flooded at high electrical density, and the performance is reduced. Therefore, a new water management scheme capable of matching the gravitational field distribution is urgently needed, and different areas of the membrane electrode can be differentiated so as to solve the problems of drying risk of the upper half and flooding of the lower half at the same time. Disclosure of Invention The present invention has been made based on the findings and knowledge of the inventors regarding the following facts and problems: CN116435525A discloses a graded gas diffusion layer, the gradient is along the horizontal direction (gas inlet to outlet), mainly to cope with the problems of gradually decreasing concentration of the reaction gas along the flow channel and gradually increasing the generated water. In fuel cells, however, there is a great difference in the accumulation and distribution of liquid water mainly in the vertical direction (from top to bottom) due to gravity, and the flooding problem at the bottom is much higher than at the top. A horizontal wettability gradient is ineffective in draining excess water accumulated at the bottom of the cell. CN115241506a discloses a preparation method of a membrane electrode in which ionic liquid is distributed in a gradient manner along the inlet and outlet directions, and the preparation method cannot realize two different functional requirements of 'strong moisture retention' of a top area and 'stron