Proton exchange membrane structure and membrane electrode
By embedding a discontinuous free radical quenching layer on the surface of the proton exchange membrane, the problem of chemical degradation of the proton exchange membrane caused by free radical attack is solved, the chemical stability and lifetime of the membrane electrode are improved, and the proton conduction performance remains unchanged.
Patent Information
- Application Number
- CN202520084621.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-14
- Publication Date
- 2026-02-24
- Estimated Expiration
- 2035-01-14
AI Technical Summary
In fuel cells, proton exchange membranes undergo irreversible chemical degradation due to free radical attack, affecting cell lifespan.
A discontinuous free radical quenching layer is embedded on the surface of a proton exchange membrane. It is prepared by coating with a dispersion emulsion containing a free radical quencher. The layer is uniformly or randomly distributed by means of template method, screen printing or atomization spraying. The shape is regular or irregular circular, elliptical or polygonal, with a thickness of 1-3 μm, accounting for 1/5-2/3 of the membrane area, and the content is 0.01-0.2 mg/cm2.
It effectively captures free radicals generated during fuel cell operation, improves the chemical stability of the membrane electrode, extends the life of the proton exchange membrane, and does not increase the resistance of the proton conduction path.
Smart Images
Figure CN223941795U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of proton exchange membrane structure technology, specifically relating to a proton exchange membrane structure and membrane electrode. Background Technology
[0002] The statements herein provide only background information related to this invention and do not necessarily constitute prior art.
[0003] The membrane electrode assembly (MEA) is the core component of a proton exchange membrane fuel cell (PEMFC), and it has a crucial impact on the overall performance, lifespan, and cost of the fuel cell. A typical MEA consists of a proton exchange membrane, a cathode catalyst layer, an anode catalyst layer, a cathode gas diffusion layer, and an anode gas diffusion layer. The proton exchange membrane is the core component. It is generally composed of a perfluorosulfonic acid membrane, consisting of a fluorocarbon backbone and ether branches with sulfonic acid groups. It is an ion-selective permeable membrane that provides a channel for proton migration and transport, separates gaseous reactants, and blocks electrolytes. During the reaction, it allows only hydrogen ions (protons) that have lost electrons at the anode to pass through to the cathode, while blocking electrons, hydrogen molecules, water molecules, etc., making it the most critical component of the fuel cell.
[0004] However, proton exchange membranes (PEMs) undergo continuous and irreversible chemical degradation caused by free radicals during battery operation. The chemical degradation of perfluorosulfonic acid (PFS) PEMs originates from attacks by free radicals such as OH· and OOH·. Transition metal impurities such as Fe2+ can be introduced during battery raw material production, handling, assembly, reactant gas impurities, and component release. 2+ H2O2 and Fe 2+ The Fenton reaction generates free radicals. These free radicals attack the perfluorosulfonic acid proton exchange membrane (PTM), causing cracks, pinholes, and thinning. This process is accompanied by the release of fluoride ions, affecting the PTM's lifespan. Therefore, the chemical degradation of the PTM causes irreversible damage to the battery, severely reducing its lifespan. Utility Model Content
[0005] The purpose of this invention is to provide a proton exchange membrane structure and membrane electrode, wherein a discontinuous free radical quenching thin layer is formed on one or both sides of the proton membrane, which does not increase the thickness of the proton membrane and the proton conduction resistance, while being able to withstand free radical attacks.
[0006] To achieve the above objectives, this utility model is implemented through the following technical solution:
[0007] In a first aspect, embodiments of the present invention provide a proton exchange membrane structure, including a proton exchange membrane, wherein a discontinuous free radical quenching layer is embedded on the surface of the proton exchange membrane, and the free radical quenching layer is prepared by coating with a dispersion emulsion containing a free radical quencher.
[0008] As a further technical solution, the free radical quenching layer is embedded on one or both sides of the proton exchange membrane.
[0009] As a further technical solution, the free radical quenching layer is uniformly or randomly distributed on the surface of the proton exchange membrane, and the shape of the free radical quenching layer is either regular or irregular.
[0010] As a further technical solution, the free radical quenching layer embedded on the surface of the proton exchange membrane can be of different sizes and the same or different shapes.
[0011] As a further technical solution, the shape of the free radical quenching layer can be circular, elliptical, or polygonal.
[0012] As a further technical solution, when the free radical quenching layer is uniformly distributed on the surface of the proton exchange membrane, the free radical quenching layer is embedded by template method or screen printing; when the free radical quenching layer is randomly distributed on the surface of the proton exchange membrane, the free radical quenching layer is embedded by atomization spray method.
[0013] As a further technical solution, the thickness of the free radical quenching layer is 1-3 μm.
[0014] As a further technical solution, the content of free radical quencher in the embedded free radical quenching layer is 0.01–0.2 mg / cm³. 2 .
[0015] As a further technical solution, the free radical quenching layer occupies 1 / 5 to 2 / 3 of the surface area of the proton exchange membrane.
[0016] Secondly, embodiments of the present invention provide a membrane electrode comprising the proton exchange membrane structure described in the first aspect.
[0017] The beneficial effects of the above-described embodiments of this utility model are as follows:
[0018] (1) The proton exchange membrane structure provided by this utility model embeds a dispersion containing free radical quenching components on the surface of the proton exchange membrane, so that a discontinuous free radical quenching thin layer is embedded on one or both sides of the proton membrane, which can capture free radicals generated during the operation of the fuel cell in situ, greatly alleviate the attack of free radicals on perfluorosulfonic acid resin, and improve the chemical stability of the membrane electrode.
[0019] (2) The proton exchange membrane structure provided by this utility model uses a template method, screen printing, or atomized spraying to embed a dispersion containing free radical quenching components. This is a one-step operation, simple in method, and the thin-layer structure is not limited. It can be randomly or uniformly distributed, with diverse forms, simple operation, and obvious effect. The free radical quenching components are embedded in the proton membrane in a discontinuous form, which hardly increases the thickness of the proton membrane, does not change the proton conduction path, and does not increase the conduction resistance. That is, it improves the free radical tolerance without changing the intrinsic properties of the proton membrane. Attached Figure Description
[0020] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.
[0021] Figure 1 For existing blank proton exchange membranes;
[0022] Figure 2 This invention relates to a proton exchange membrane containing a uniformly distributed, regularly shaped free radical quenching layer.
[0023] Figure 3 This invention relates to a proton exchange membrane containing a randomly distributed, irregularly shaped free radical quenching layer.
[0024] Figure 4 This is a comparison chart showing the mass retention rate of proton exchange membranes with and without free radical quenching layers in Fenton's reagent.
[0025] Figure 5 The values of hydrogen permeation current density change of the proton exchange membranes of this invention with and without free radical quenching layers before and after single-cell open-circuit (OCV) accelerated durability test are shown. (a) is the proton exchange membrane without free radical quenching layer, and (b) is the proton exchange membrane with free radical quenching layer.
[0026] The diagram is for illustrative purposes only.
[0027] Among them, 1. Proton exchange membrane; 2. Free radical quenching layer. Detailed Implementation
[0028] It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0029] Example 1
[0030] In a typical embodiment of this utility model, such as Figure 2 and Figure 3 As shown, a proton exchange membrane structure is provided, including a proton exchange membrane 1, on the surface of which a discontinuous free radical quenching layer 2 is embedded, wherein the free radical quenching layer 2 is prepared by coating with a dispersion emulsion containing a free radical quencher.
[0031] This proton exchange membrane structure is in Figure 1 Based on existing unmodified proton exchange membranes, a discontinuous free radical quenching thin layer is obtained by embedding a dispersion containing free radical quenching components into one or both sides of the proton membrane through certain means and then drying it. This does not increase the thickness of the proton membrane or the proton conduction resistance, while being able to withstand free radical attacks.
[0032] In this embodiment, the free radical quenching layer is embedded on one or both sides of the proton exchange membrane.
[0033] In this embodiment, the free radical quenching layer is uniformly or randomly distributed on the surface of the proton exchange membrane, and the shape of the free radical quenching layer can be regular or irregular. Further, as... Figure 2 and Figure 3 As shown, the free radical quenching layers embedded on the surface of the proton exchange membrane are of different sizes and the same or different shapes. Specifically, the free radical quenching layers are circular, elliptical, or polygonal in shape.
[0034] In this embodiment, when the free radical quenching layer is uniformly distributed on the surface of the proton exchange membrane, it is embedded using a template method or screen printing; when the free radical quenching layer is randomly distributed on the surface of the proton exchange membrane, it is embedded using an atomization spray method. The template method involves covering part of the proton exchange membrane surface with a template, embedding the free radical quencher only in the exposed areas. Discontinuous embedding of the free radical quencher can be achieved by changing parameters such as the shape and coverage area of the template. Screen printing achieves discontinuous embedding by designing specific screen patterns so that the free radical quencher is coated only in the desired areas. Atomization spray can be achieved using a sprayer, spray gun, nano-sprayer, etc.
[0035] In this embodiment, the thickness of the free radical quenching layer is 1-3 μm.
[0036] In this embodiment, the content of free radical quencher in the embedded free radical quenching layer is 0.01-0.2 mg / cm³. 2 Furthermore, the free radical quenching layer occupies 1 / 5 to 2 / 3 of the surface area of the proton exchange membrane, which ensures that the thickness of the proton membrane is hardly increased, the proton conduction path is not changed, and the conduction resistance is not increased. That is, while improving the free radical tolerance, the intrinsic properties of the proton membrane are not changed.
[0037] The proton exchange membrane structure provided in this embodiment is a three-layer or multi-layer structure, which can be a fluorosulfonic acid type proton exchange membrane, a Nafion recast membrane, a non-fluoropolymer proton exchange membrane, a novel composite proton exchange membrane, etc., with a thickness of 6-50 μm. The dispersion emulsion used to prepare the free radical quenching layer includes a free radical quencher and a solvent. The free radical quencher includes cerium oxide and its derivatives, or other inorganic oxides such as manganese oxide and cobalt oxide, or aromatic organic compounds. The solvent uses water, ethanol, isopropanol, etc. A uniform dispersion emulsion can be obtained by one or more methods such as ultrasonication, cell disruption, mechanical stirring, or Primix, with the concentration of the dispersion emulsion controlled at 0.02%-0.5%. The amount of free radical quencher added can be calculated by weighing after drying, ensuring that the free radical quencher content on the proton membrane is 0.01-0.2 mg / cm³. 2 During drying, the solvent is evaporated by heating at room temperature or low temperature, and the heating temperature is required to be ≤100℃.
[0038] The following provides two specific methods for preparing proton exchange membrane structures:
[0039] Implementation Method 1
[0040] A regular template was applied to the surface of a blank proton exchange membrane. Then, a dispersion emulsion containing a free radical quencher was embedded onto the surface of the proton exchange membrane by coating or screen printing until the CeO2 content on one side of the proton exchange membrane reached 0.05 mg / cm³. 2 Then, the same process is repeated on the other side, followed by drying and weighing, until the CeO2 content on the proton exchange membrane on the other side is 0.1 mg / cm³. 2 This results in a uniformly distributed, regular free radical quenching thin-layer structure.
[0041] The preparation of the free radical quencher-containing dispersion emulsion was achieved by dispersing CeO2 nanoparticles in a solution of Nafion (perfluorosulfonic acid) and isopropanol (Nafion mass ratio of 1%), controlling the concentration at 0.1%, mechanically stirring for 30 min, and ultrasonically dispersing for 30 min.
[0042] like Figure 2 As shown, the free radical quenching layer is a regular, discontinuously distributed layer with uniform size and shape on the surface of the proton exchange membrane.
[0043] Implementation Method 2:
[0044] A dispersion emulsion containing a free radical quencher was atomized using a nano-sprayer. The atomizing nozzle was aimed at one side of the proton exchange membrane, and the mixture was dried and weighed until the CeO2 content on one side of the proton exchange membrane reached 0.05 mg / cm³. 2Then spray the other side, dry and weigh, until the CeO2 content on the other proton exchange membrane is 0.1 mg / cm³. 2 This results in a randomly distributed, irregularly quenched thin-layer structure of free radicals.
[0045] The preparation of the free radical quencher-containing dispersion emulsion was achieved by dispersing CeO2 nanoparticles in a solution of Nafion and isopropanol (Nafion mass ratio of 1%), controlling the concentration at 0.1%, mechanically stirring for 30 min, and ultrasonically dispersing for 30 min.
[0046] like Figure 3 As shown, the free radical quenching components are distributed discontinuously in the form of dots of uneven size on the surface of the proton membrane.
[0047] The following verification was performed on a proton exchange membrane containing a free radical quenching thin-layer structure and a blank proton exchange membrane:
[0048] 1) Prepare Fenton's solution according to the ratio of Fe(NH4)2·(SO4)·6H2O:3% H2O2 = 7mg:100mL. Immerse the proton exchange membrane (weight m1) in Fenton's solution at 80℃ for 4 hours. Remove, dry and weigh, and record as m2. Mass retention rate = [(m1-m2) / m1]×100%.
[0049] 2) Proton exchange membrane accelerated durability test in single cell open circuit (OCV): The cathode catalyst layer was sprayed on the proton exchange membrane side with CeO2 content of 1000ppm, and the anode catalyst layer was sprayed on the side with CeO2 content of 2000ppm, and a gas diffusion layer was used for single cell testing.
[0050] The test conditions were: battery temperature 90℃, anode / cathode ratio 30% / 30%, anode / cathode H2 / Air stoichiometric ratio 10 / 10, pressure 50 kPa, and continuous operation of the open-circuit OCV for 500 hours. The change in proton exchange membrane hydrogen permeation current density before and after the durability test was performed.
[0051] The results are as follows Figure 4 As shown, the mass retention rate of the proton exchange membrane without free radical quenchers was only 89.3% after treatment with Fenton's reagent, while the mass retention rate of the proton exchange membrane with free radical quenchers was as high as 98.9% in Fenton's reagent, indicating that the proton exchange membrane after being constructed with free radical quenchers has good resistance to free radical attack.
[0052] like Figure 5 As shown, the hydrogen permeation current density of the two proton exchange membranes before and after durability testing was compared. Before durability testing, the hydrogen permeation current density (the current density corresponding to a voltage of 0.4V) of the proton exchange membrane was 3.5 mA / cm². 2 After approximately 500 hours of durability testing, the hydrogen permeation current density of the proton exchange membrane without embedded free radical quenchers was 7.8 mA / cm².2 The hydrogen permeation current density of the proton exchange membrane with surface-embedded free radical quenchers is 3.7 mA / cm². 2 .
[0053] Example 2
[0054] In a typical embodiment of this utility model, a membrane electrode is provided, including the proton exchange membrane structure as described in Example 1.
[0055] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. A proton exchange membrane structure, characterized in that, The invention includes a proton exchange membrane, on the surface of which a discontinuous free radical quenching layer is embedded, the free radical quenching layer being prepared by coating with a dispersion emulsion containing a free radical quencher.
2. The proton exchange membrane structure as described in claim 1, characterized in that, The free radical quenching layer is embedded on one or both sides of the proton exchange membrane.
3. The proton exchange membrane structure as described in claim 1, characterized in that, The free radical quenching layer is uniformly or randomly distributed on the surface of the proton exchange membrane, and the shape of the free radical quenching layer can be regular or irregular.
4. The proton exchange membrane structure as described in claim 3, characterized in that, The free radical quenching layers embedded on the surface of the proton exchange membrane can be of different sizes and the same or different shapes.
5. The proton exchange membrane structure as described in claim 3, characterized in that, The free radical quenching layer can be circular, elliptical, or polygonal in shape.
6. The proton exchange membrane structure as described in claim 3, characterized in that, When the free radical quenching layer is uniformly distributed on the surface of the proton exchange membrane, it is embedded using a template method or screen printing; when the free radical quenching layer is randomly distributed on the surface of the proton exchange membrane, it is embedded using an atomization spray method.
7. The proton exchange membrane structure as described in claim 1, characterized in that, The thickness of the free radical quenching layer is 1-3 μm.
8. The proton exchange membrane structure as described in claim 1, characterized in that, The content of free radical quencher in the embedded free radical quenching layer is 0.01–0.2 mg / cm³. 2 .
9. The proton exchange membrane structure as described in claim 1, characterized in that, The free radical quenching layer occupies 1 / 5 to 2 / 3 of the surface area of the proton exchange membrane.
10. A membrane electrode, characterized in that, Including the proton exchange membrane structure as described in any one of claims 1-9.