Method for improving durability of membrane electrode by adopting imidazolium ionic liquid
By using imidazole ionic liquid as a protective layer in the membrane electrode and diffusing it deeply into the HSA by freezing, the transmission resistance problem of the catalytic layer under high current density conditions is solved, and higher catalytic efficiency and durability are achieved.
Patent Information
- Application Number
- CN202510245302.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-04
- Publication Date
- 2025-06-06
AI Technical Summary
Under the conditions of high current density, the local transport resistance of the catalytic layer is obvious, which causes water molecules to be unable to effectively transport protons to the active site of platinum Pt, limiting the performance of the catalytic layer.
Imidazole ionic liquid is used as the protective layer, and the ionic liquid is diffused deeply into the micropores and smaller mesopores in HSA through freezing, so that protons can be efficiently transported to the active sites of platinum.
It effectively protects the Pt surface, reduces the oxidation and aging of platinum, improves the catalytic efficiency, extends the durability of the membrane electrode, and avoids the toxicity of sulfonic acid groups to Pt.
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Figure CN120109240A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of membrane electrode manufacturing, and in particular to a method for improving the durability of a membrane electrode by using imidazole ionic liquid. Background Art
[0002] As a clean, efficient and sustainable energy source, hydrogen energy is considered one of the most promising energy solutions. Fuel cell vehicles, as an important way to utilize hydrogen energy, have ushered in a booming trend due to their high efficiency and zero emissions. In fuel cell vehicles, the membrane electrode (MEA) is its most core component, and the catalyst layer is the key part of the MEA. However, improving the durability of the catalyst layer has become a difficulty and focus of development in the industry.
[0003] High specific surface area (HSA) carbon carriers have become the preferred material for fuel cells due to their rich internal mesoporous structure. HSA carbon carriers can accommodate up to 75% of platinum catalysts (mesopore size is 5-14 nanometers), which makes them exhibit high activity in oxygen reduction reaction (ORR). However, under high current density conditions, the local transport resistance problem of HSA carbon carriers becomes more obvious. Specifically, water molecules cannot completely and effectively transfer protons to the active sites of platinum Pt, thereby limiting the performance of the catalytic layer. Therefore, how to improve the hydrophilic and hydrophobic properties of the catalytic layer, especially under high potential mass transfer conditions, how to quickly bring oxygen to the platinum Pt reaction point, thereby improving the performance of the overall membrane electrode, is a technical problem that needs to be solved urgently. Summary of the invention
[0004] The main technical problem solved by the present invention is to provide a method for improving the durability of membrane electrode by using imidazole ionic liquid. The ionic liquid is added to the catalytic layer and the ionic liquid is diffused deeply into the micropores and smaller mesopores of HSA by freezing, so that the membrane electrode has excellent initial performance and durability.
[0005] In order to solve the above technical problems, a technical solution adopted by the present invention is: to provide a method for improving the durability of membrane electrode by using imidazole ionic liquid, comprising the following steps: (1) Preparing a proton exchange membrane: cutting a proton membrane as a proton exchange membrane; (2) Preparing catalyst slurry: Weigh a certain amount of catalyst, using PtRu / C catalyst for the anode and Pt / C catalyst for the cathode, using an organic solvent as a dispersion liquid, and dispersing the catalysts into a cathode catalyst slurry and an anode catalyst slurry respectively; (3) Spraying catalyst slurry: Spray the dispersed cathode and anode catalyst slurries evenly on both sides of the proton exchange membrane, with the anode catalyst loading being 0.05-0.1 mg / cm² and the cathode catalyst loading being 0.3-0.4 mg / cm², to form a catalyst coating membrane CCM1; (4) Spraying imidazole ionic liquid: After uniformly mixing the imidazole derivative solution with the organic solvent, spray it again on both sides of CCM1, spray 4 to 6 times on the anode and 6 to 8 times on the cathode, and then freeze and store it to form a catalyst coating membrane CCM2; (5) Hot pressing: CCM2 and the diffusion layer are hot pressed to form an improved membrane electrode assembly.
[0006] In a preferred embodiment of the present invention, the proton membrane in step (1) is Gore 765.08 membrane, Gore 788.12 membrane or Gore 775.15 membrane.
[0007] In a preferred embodiment of the present invention, the anode in step (2) uses a PtRu / C catalyst with a mass fraction of platinum Pt of 20% and a mass fraction of ruthenium Ru of 5%.
[0008] In a preferred embodiment of the present invention, the Pt / C catalyst used in the cathode in step (2) is one of 40% Pt / C catalyst, 50% Pt / C catalyst and 60% Pt / C.
[0009] In a preferred embodiment of the present invention, the organic solvent in step (2) and step (4) is one or more of isopropanol, n-butanol, n-propanol, ethylene glycol and NMP.
[0010] In a preferred embodiment of the present invention, the imidazole derivative in step (4) is one or more of [C2mim]+[NTf2]-, [C4mim]+[NTf2]- and [C4dmim]+[NTf2]-.
[0011] In a preferred embodiment of the present invention, the mass ratio of the imidazole derivative to the solvent in step (4) is 0.1-1:5-10.
[0012] In a preferred embodiment of the present invention, the frozen storage in step (4) is to place the sprayed CCM1 in a freezer at -20°C to -10°C for 6 to 8 hours.
[0013] In a preferred embodiment of the present invention, the diffusion layer in step (5) is one or more of Toray055, Freudenberg H23CX653 and Freudenberg H15CX653.
[0014] In a preferred embodiment of the present invention, in step (5), the hot pressing temperature is 100-120°C, the hot pressing pressure is 0-60 kPa, and the hot pressing time is 20-80 s.
[0015] The beneficial effects of the present invention are as follows: the present invention can effectively protect Pt in contact with the ionic liquid by adding an ionic liquid as a protective layer, prevent its surface from being attacked by oxygen-containing groups, thereby reducing the oxidation and aging of platinum; the ionic liquid is deeply diffused into the micropores and smaller mesopores of HSA by freezing, which can provide an effective proton transport means for Pt, and under high current density conditions, it is ensured that protons can efficiently reach the active sites of platinum, thereby improving the catalytic efficiency; because the ionic liquid is filled into the micropores and smaller mesopores, the sulfonic acid group (-SO 3 ) to Pt toxicity, and at the same time prevent the deactivation of the membrane electrode caused by Pt particle agglomeration, so that the entire membrane electrode maintains high activity and durability. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which: Figure 1 It is the Zeta bar graph of the imidazole dispersions of Examples 1-3 of the present invention and Comparative Example 1. DETAILED DESCRIPTION
[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.
[0018] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0019] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.
[0020] In the description of the present invention, it should be noted that the terms "front", "rear", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is usually placed when in use, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.
[0021] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0022] In the present invention, unless otherwise clearly specified and limited, a first feature being above or below a second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them. Moreover, a first feature being above, above, and above a second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being below, below, and below a second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.
[0023] The embodiments of the present invention include: Embodiment 1: A method for improving the durability of a membrane electrode using an imidazole ionic liquid comprises the following steps: (1) Cut 5*5 cm Gore788.12 membrane as proton exchange membrane.
[0024] (2) Weigh 0.2 g of PtRu / C catalyst, 10 mL of ethylene glycol, and 10 mL of deionized water, and mix them in an ice bath for 15 min to prepare the anode slurry.
[0025] Weigh 0.2 g of 50% Pt / C catalyst, 10 mL of ethylene glycol, and 10 mL of deionized water, and disperse them in an ice bath with stirring for 15 min to prepare cathode slurry.
[0026] (3) Spray the anode and cathode slurries on both sides of the proton exchange membrane respectively, and control the anode Pt loading to 0.05 mg / cm 2, the cathode Pt loading is controlled at 0.3 mg / cm 2 , as CCM1.
[0027] (4) Weigh 0.2 g [C2mim] + [NTf2] - , 10mL ethylene glycol, mixed for 10 minutes using an ice bath spherical ink method, sprayed the mixed slurry on the anode 4 times and the cathode 8 times, placed in a freeze drying box at -20°C, stored for 6 hours, and made CCM2.
[0028] (5) The prepared CCM2 and Toray TGL-R055 were hot-pressed at a temperature of 100°C, a time of 60 seconds, and a pressure of 60 kPa to form an improved membrane electrode assembly.
[0029] The improved membrane electrode assembly was placed in a fuel cell test system for testing. Embodiment 2:
[0030] A method for improving the durability of a membrane electrode using an imidazole ionic liquid comprises the following steps: (1) Cut 5*5 cm Gore788.12 membrane as proton exchange membrane.
[0031] (2) Weigh 0.3 g of PtRu / C catalyst, 12 mL of isopropanol, and 12 mL of deionized water, and mix them in an ice bath for 15 min to prepare the anode slurry.
[0032] Weigh 0.3 g of 60% Pt / C catalyst, 15 mL of isopropanol, and 15 mL of deionized water, and disperse them in an ice bath with stirring for 15 min to prepare cathode slurry.
[0033] (3) Spray the anode and cathode slurries on both sides of the proton exchange membrane respectively, and control the anode Pt loading to 0.1 mg / cm 2 , the cathode Pt loading is controlled at 0.4 mg / cm 2 , as CCM1.
[0034] (4) Weigh 0.3 g [C4mim] + [NTf2] - , 12mL of isopropanol, mixed for 12 minutes using an ice bath spherical ink method, sprayed the mixed slurry on the anode 6 times and the cathode 6 times, placed in a freeze drying box at -15°C, stored for 6 hours, and made CCM2.
[0035] (5) The prepared CCM2 and Freudenberg diffusion layer H23CX653 were hot-pressed at a temperature of 120°C, a time of 60 seconds, and a pressure of 40 kPa to form an improved membrane electrode assembly.
[0036] The improved membrane electrode assembly was placed in a fuel cell test system for testing. Embodiment 3:
[0037] A method for improving the durability of a membrane electrode using an imidazole ionic liquid comprises the following steps: (1) Cut 5*5 cm Gore775.15 membrane as proton exchange membrane.
[0038] (2) Weigh 0.2 g of PtRu / C catalyst, 15 mL of n-propanol, and 12 mL of deionized water, and mix them in an ice bath for 12 min to prepare the anode slurry. Weigh 0.25 g of 40% Pt / C catalyst, 10 mL of isopropanol, and 12 mL of deionized water, and disperse them in an ice bath for 10 min to prepare the cathode slurry.
[0039] (3) Spray the anode and cathode slurries on both sides of the proton exchange membrane respectively, and control the anode Pt loading to 0.05 mg / cm 2 , the cathode Pt loading is controlled at 0.4 mg / cm 2 , as CCM1.
[0040] (4) Weigh 0.3 g [C4dmim] + [NTf2] - , 12mL isopropanol, mixed for 12min using ice bath spherical ink, sprayed the mixed slurry on the anode 6 times and the cathode 6 times, placed in a -15℃ freeze drying box, stored for 8h, to make CCM2 (5) The prepared CCM2 and Freudenberg diffusion layer H15CX653 were hot-pressed at a temperature of 120°C, a time of 60 seconds, and a pressure of 50 kPa to form an improved membrane electrode assembly.
[0041] The improved membrane electrode assembly is placed in a fuel cell test system to prepare for testing.
[0042] Comparative Example 1: A membrane electrode preparation method comprises the following steps: (1) Cut 5*5 cm Gore 12µm membrane as proton exchange membrane.
[0043] (2) Weigh 0.2 g of PtRu / C catalyst, 10 mL of ethylene glycol, and 10 mL of deionized water, and mix them in an ice bath for 15 min to prepare the anode slurry. Weigh 0.2 g of 50% Pt / C catalyst, 10 mL of ethylene glycol, and 10 mL of deionized water, and disperse them in an ice bath for 15 min to prepare the cathode slurry.
[0044] (3) Spray the anode and cathode slurries on both sides of the proton exchange membrane respectively, and control the anode Pt loading to 0.05 mg / cm 2 , the cathode Pt loading is controlled at 0.3 mg / cm 2 , as CCM1.
[0045] (4) The sprayed CCM1 and Toray TGL-R055 were hot-pressed at a temperature of 120°C, a time of 60 seconds, and a pressure of 50 kPa to form a membrane electrode assembly.
[0046] The membrane electrode assembly was placed in a fuel cell test system in preparation for durability testing.
[0047] The polarization test conditions in the fuel cell test system of Examples 1-3 and Comparative Example 1 are as follows: scan from open circuit potential to 0.55 V, run for 3 min at each current, anode stoichiometric ratio of 1.2, cathode stoichiometric ratio of 2.5. Anode humidity 100% RH, cathode humidity 100% RH, hydrogen back pressure 200 kPa, air back pressure 200 kPa, anode 80°C, cathode 80°C, single cell temperature 80°C.
[0048] The durability test conditions in the fuel cell test system of Examples 1-3 and Comparative Example 1 are as follows: the temperature of the single fuel cell is set at 80°C, the anode and cathode are respectively charged at 100 mL min -1 The flow rate supplies H with a relative humidity of 100%. 2 , and at 40 mL min -1 The flow rate supplies N with a relative humidity of 100%. 2 The square wave cycling was performed by alternating between 0.6 V and 0.95 V for 30,000 cycles, with each step lasting 3 seconds and a rise time of approximately 0.5 seconds or less.
[0049] After cycling 0, 10,000, and 30,000 times at a square wave potential of 0.6-0.95 V, a polarization test was performed to obtain the final data, as shown in Table 1: Table 1 Comparison of current density at 0.65V between Examples 1-3 and Comparative Example 1 after 0.6-0.95V square wave accelerated Pt durability test for 0, 10000, and 30000 cycles Number of cycles <![CDATA[Example 1 (A / cm 2 ).]]> <![CDATA[Example 2 (A / cm 2 ).]]> <![CDATA[Example 3 (A / cm 2 )]]> <![CDATA[Comparative Example 1 (A / cm 2 )]]> 0 2.835 2.913 2.732 2.512 10000 2.324 2.213 2.489 0.732 30000 1.876 1.723 1.787 0.543 The initial membrane electrode was subjected to a Zeta potential test, and the membrane electrode after 5000 cycles of aging was subjected to a Zeta potential test, such as Figure 1 shown.
[0050] Through Table 1 and Figure 1 The test data can be analyzed to obtain: The embodiment of the present invention using ionic liquid has a smaller performance degradation after 5K cycles of aging because the addition of ionic liquid avoids the adsorption of oxygen-containing groups on Pt, avoids the agglomeration of Pt, and reduces the corrosion of the carbon carrier. The Zeta potential also explains this problem. The electrostatic repulsion between the groups of ionic liquid molecules and the organic functional groups can make higher local charges and Zeta potentials, stabilizing Pt.
[0051] Therefore, the present invention can effectively protect Pt in contact with the ionic liquid by adding the ionic liquid as a protective layer, preventing its surface from being attacked by oxygen-containing groups, thereby reducing the oxidation and aging of platinum.
[0052] The use of freezing to diffuse ionic liquids deeply into the micropores and smaller mesopores of HSA can provide an effective means of proton transport for Pt. Under high current density conditions, it ensures that protons can efficiently reach the active sites of platinum, thereby improving the catalytic efficiency.
[0053] Since the ionic liquid fills the micropores and smaller mesopores, the sulfonic acid groups (-SO 3 ) to Pt toxicity, and at the same time prevent the deactivation of the membrane electrode caused by Pt particle agglomeration, so that the entire membrane electrode maintains high activity and durability.
[0054] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.
Claims
1. A method for improving the durability of a membrane electrode using imidazole ionic liquids, characterized in that: The following steps are involved: (1) Preparing a proton exchange membrane: cutting a proton membrane as a proton exchange membrane; (2) Preparing catalyst slurry: Weigh a certain amount of catalyst, using PtRu / C catalyst for the anode and Pt / C catalyst for the cathode, using an organic solvent as a dispersion liquid, and dispersing the catalysts into a cathode catalyst slurry and an anode catalyst slurry respectively; (3) Spraying catalyst slurry: Spray the dispersed cathode and anode catalyst slurries evenly on both sides of the proton exchange membrane, with the anode catalyst loading being 0.05-0.1 mg / cm² and the cathode catalyst loading being 0.3-0.4 mg / cm², to form a catalyst coating membrane CCM1; (4) Spraying imidazole ionic liquid: After uniformly mixing the imidazole derivative solution with the organic solvent, spray it again on both sides of CCM1, spray 4 to 6 times on the anode and 6 to 8 times on the cathode, and then freeze and store it to form a catalyst coating membrane CCM2; (5) Hot pressing: CCM2 and the diffusion layer are hot pressed to form an improved membrane electrode assembly.
2. The method for improving the durability of membrane electrode using imidazole ionic liquid according to claim 1, characterized in that: In step (1), the proton membrane is Gore 765.08 membrane, Gore 788.12 membrane or Gore 775.15 membrane.
3. The method for improving the durability of membrane electrode using imidazole ionic liquid according to claim 1, characterized in that: In step (2), the anode uses a PtRu / C catalyst with a mass fraction of platinum Pt of 20% and a mass fraction of ruthenium Ru of 5%.
4. The method for improving the durability of membrane electrode using imidazole ionic liquid according to claim 1, characterized in that: The Pt / C catalyst used in the cathode in step (2) is one of 40% Pt / C catalyst, 50% Pt / C catalyst and 60% Pt / C catalyst.
5. The method for improving the durability of membrane electrode using imidazole ionic liquid according to claim 1, characterized in that: The organic solvent in step (2) and step (4) is one or more of isopropanol, n-butanol, n-propanol, ethylene glycol and NMP.
6. The method for improving the durability of membrane electrode using imidazole ionic liquid according to claim 1, characterized in that: In step (4), the imidazole derivative is one or more of [C2mim]+[NTf2]-, [C4mim]+[NTf2]- and [C4dmim]+[NTf2]-.
7. The method for improving membrane electrode durability using imidazole ionic liquid according to claim 1, characterized in that: In step (4), the mass ratio of the imidazole derivative to the solvent is 0.1-1:5-10.
8. The method for improving the durability of membrane electrode using imidazole ionic liquid according to claim 1, characterized in that: In step (4), the frozen storage is to place the sprayed CCM1 in a freezer at -20°C to -10°C for 6 to 8 hours.
9. The method for improving the durability of membrane electrode using imidazole ionic liquid according to claim 1, characterized in that: In step (5), the diffusion layer is one or more of Toray TGL-R055, Freudenberg H23CX653 and Freudenberg H15CX653.
10. The method for improving the durability of membrane electrode using imidazole ionic liquid according to claim 1, characterized in that: In step (5), the hot pressing temperature is 100-120°C, the hot pressing pressure is 0-60kPa, and the hot pressing time is 20-80s.