Hydroxyl radical eliminating layer, preparation method and application thereof, and membrane electrode

Abstract

The invention provides a hydroxyl radical elimination layer, a preparation method and application thereof, and a membrane electrode, and particularly relates to the technical field of proton exchange membrane fuel cells. The hydroxyl free radical eliminating layer is prepared from slurry containing a hydroxyl free radical eliminating agent; the hydroxyl free radical eliminating agent comprises NZP-Ce and / or ZP-Ce. The hydroxyl free radical scavenger in the hydroxyl free radical scavenging layer provided by the invention comprises NZP-Ce and / or ZP-Ce, and cerium is fixed on NZP or ZP for anchoring, so that migration and reaction of cerium are limited, and the free radical scavenging efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of proton exchange membrane fuel cells, and in particular to a hydroxyl radical elimination layer, a preparation method and application thereof, and a membrane electrode. Background Art

[0002] The membrane electrode is the core component of the proton exchange membrane fuel cell, which is composed of a proton exchange membrane, anode and cathode catalyst layers, and cathode and cathode gas diffusion layers. The membrane material plays an important role in the life of the membrane electrode. Damage to the membrane material will cause the failure of the membrane electrode and then the failure of the fuel cell stack.

[0003] Hydroxyl radicals are inevitably generated during the membrane electrode reaction. Hydroxyl radicals attack the molecular chains of the membrane material, causing the molecular chains to continue to be lost, thereby causing the membrane to be destroyed and small holes to be formed. The ability to block gas is reduced, leading to failure.

[0004] The life of the membrane is improved by applying a CeO2 coating on the membrane to eliminate hydroxyl radicals, but studies have found that the electric field can cause the migration of cerium ions; the cerium ions may cooperate with the sulfonic acid groups on the membrane, resulting in a decrease in proton conductivity.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] One of the purposes of the present invention is to provide a hydroxyl radical scavenging layer to alleviate the technical problems of cerium ion migration and reduced proton conductivity caused by CeO2 as a hydroxyl radical scavenger in the prior art.

[0007] A second object of the present invention is to provide a method for preparing a hydroxyl radical elimination layer.

[0008] A third object of the present invention is to provide an application of a hydroxyl radical elimination layer in a membrane electrode.

[0009] A fourth object of the present invention is to provide a membrane electrode.

[0010] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0011] The first aspect of the present invention provides a hydroxyl radical scavenging layer, which is made of a slurry containing a hydroxyl radical scavenger;

[0012] The hydroxyl radical scavenger includes NZP-Ce and / or ZP-Ce.

[0013] Furthermore, the slurry also includes water, alcohol and perfluorosulfonic acid resin solution.

[0014] Preferably, the alcohol includes at least one of ethanol, ethylene glycol, n-propanol, isopropanol and glycerol.

[0015] Preferably, the water includes deionized water, distilled water and ultrapure water, preferably ultrapure water.

[0016] Furthermore, the slurry includes, by weight, 10-20 parts of a hydroxyl radical scavenger, 50-65 parts of water, 3-12 parts of alcohol, and 10-30 parts of a perfluorosulfonic acid resin solution.

[0017] Preferably, in parts by weight, the slurry comprises 13-17 parts of hydroxyl radical scavenger, 56-60 parts of water, 5-10 parts of alcohol and 13-26 parts of perfluorosulfonic acid resin solution.

[0018] Furthermore, in the perfluorosulfonic acid resin solution, the perfluorosulfonic acid resin accounts for 5wt.%-20wt.%.

[0019] The second aspect of the present invention provides a method for preparing the hydroxyl radical elimination layer, wherein the slurry is coated on a substrate and then dried to obtain the hydroxyl radical elimination layer.

[0020] Furthermore, the coating method includes spraying, slit coating or screen printing.

[0021] Preferably, the drying temperature is 50°C-70°C.

[0022] The third aspect of the present invention provides the use of the hydroxyl radical elimination layer in a membrane electrode.

[0023] A fourth aspect of the present invention provides a membrane electrode, comprising a proton exchange membrane, an anode and cathode catalyst layers, and an cathode and cathode gas diffusion layers;

[0024] The hydroxyl radical elimination layer is arranged on at least one surface of the proton exchange membrane.

[0025] Furthermore, the hydroxyl radical elimination layer is arranged on a side close to the anode catalyst layer.

[0026] Preferably, the thickness of the hydroxyl radical elimination layer is 1 μm-5 μm.

[0027] Furthermore, the hydroxyl radical elimination layer is formed by coating on the proton exchange membrane through a transfer method, a direct coating method or a spray coating method.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] The hydroxyl radical scavenger in the hydroxyl radical scavenging layer provided by the present invention includes NZP-Ce and / or ZP-Ce. By anchoring cerium on NZP or ZP, the migration and reaction of cerium are restricted, thereby improving the free radical scavenging efficiency.

[0030] The preparation method provided by the invention has simple process, is easy to operate and can realize industrial production.

[0031] The application of the hydroxyl radical elimination layer provided by the present invention in the membrane electrode effectively reduces the free radical concentration in the proton exchange membrane, thereby reducing the degradation of the proton exchange membrane structure, increasing the life of the proton exchange membrane, and thereby increasing the life of the membrane electrode.

[0032] The membrane electrode provided by the present invention uses a better hydroxyl radical scavenger. In view of the beneficial effects of the above-mentioned hydroxyl radical scavenging layer, the membrane electrode has a better effect, expands the application scenarios of the membrane electrode, and promotes the development of downstream industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 A schematic diagram of the structure of the first membrane electrode provided by the present invention;

[0035] Figure 2 A schematic diagram of the structure of a second membrane electrode provided by the present invention;

[0036] Figure 3 This is a schematic diagram of the structure of the third membrane electrode provided by the present invention.

[0037] Icon: 10-proton exchange membrane; 20-cathode catalyst layer; 30-cathode gas diffusion layer; 40-hydroxyl radical elimination layer; 42-first hydroxyl radical elimination layer; 44-second hydroxyl radical elimination layer; 50-anode catalyst layer; 60-anode gas diffusion layer. DETAILED DESCRIPTION

[0038] The embodiments of the present invention will be described in detail below in conjunction with the embodiments and examples, but those skilled in the art will understand that the following embodiments and examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0039] The first aspect of the present invention provides a hydroxyl radical scavenging layer, which is made of a slurry containing a hydroxyl radical scavenger;

[0040] The hydroxyl radical scavenger includes NZP-Ce and / or ZP-Ce.

[0041] The hydroxyl radical scavenger in the hydroxyl radical scavenging layer provided by the present invention includes NZP-Ce and / or ZP-Ce. By anchoring cerium on NZP or ZP, the migration and reaction of cerium are restricted, thereby improving the free radical scavenging efficiency.

[0042] The NZP described in the present invention is a broad sense of NZP, i.e., NZP family phosphate compounds, the parent composition of which is NaZr2(PO4)3 (referred to as NZP). NZP family phosphate compounds represent a class of compounds with the same crystal structure and adjustable chemical composition, and their general chemical formula is:

[0043] M Ⅰ M Ⅱ A2(BO4)3;

[0044] M Ⅰ The position can be replaced by alkali metal elements (Li + 、Na + , K + 、Ru + , Cs + ) and alkaline earth metal elements (Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ )

[0045] M Ⅱ The vacancies are usually not occupied by ions, but in a few cases they are filled by alkali metal ions;

[0046] A is a tetravalent hexacoordinate ion, mainly Zr, Ti, Sn, Nb, Cr, and Sr; B is a pentavalent four-coordinate ion, mainly Si, P, and S.

[0047] The above vacancies are filled with different ions to produce a series of derivatives with the same crystal structure.

[0048] NZP-Ce refers to a substance formed when the vacancies in the NZP family phosphate compound are filled with cerium ions. In this substance, the NZP family phosphate compound anchors the cerium ions in its structure, restricts the dissolution and transfer of the cerium ions, and reacts with hydroxyl radicals at a fixed position to eliminate them. When NZP-Ce is used as a hydroxyl radical scavenger to make a hydroxyl radical scavenging layer, the uniformity of the distribution of free radical scavenging sites is ensured, thereby increasing the life of the proton exchange membrane.

[0049] ZP is zirconium phosphate, a special phosphate used to prepare metal and rare earth element composite materials. The phosphate ions contained in the ZP component can form a composite of zirconium and cerium ions, ZP-Ce, in which some zirconium ions are partially replaced by cerium ions to form active sites for cerium ions to eliminate hydroxyl radicals.

[0050] Furthermore, the slurry also includes water, alcohol and perfluorosulfonic acid resin solution.

[0051] Perfluorosulfonic acid resin (Nafion) is the strongest known solid superacid, with good heat resistance, chemical stability and high mechanical strength.

[0052] It is used as a resin solution in the slurry. Considering that the material of the proton exchange membrane is perfluorosulfonic acid resin, resins of the same material have better compatibility and higher bonding strength when bonding.

[0053] Preferably, the alcohol includes at least one of ethanol, ethylene glycol, n-propanol, isopropanol and glycerol.

[0054] Preferably, the water includes deionized water, distilled water and ultrapure water, preferably ultrapure water.

[0055] Furthermore, the slurry includes, by weight, 10-20 parts of a hydroxyl radical scavenger, 50-65 parts of water, 3-12 parts of alcohol, and 10-30 parts of a perfluorosulfonic acid resin solution.

[0056] Preferably, in parts by weight, the slurry comprises 13-17 parts of hydroxyl radical scavenger, 56-60 parts of water, 5-10 parts of alcohol and 13-26 parts of perfluorosulfonic acid resin solution.

[0057] Among them, the typical but non-limiting weight portions of hydroxyl radical scavenger are 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts or 20 parts; the typical but non-limiting weight portions of water are 50 parts, 53 parts, 56 parts, 59 parts, 62 parts or 65 parts; the typical but non-limiting weight portions of alcohol are 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts or 12 parts; the typical but non-limiting weight portions of perfluorosulfonic acid resin solution are 10 parts, 13 parts, 16 parts, 19 parts, 22 parts, 25 parts, 26 parts or 30 parts.

[0058] Furthermore, in the perfluorosulfonic acid resin solution, the perfluorosulfonic acid resin accounts for 5wt.%-20wt.%.

[0059] When the proportion of perfluorosulfonic acid resin is less than 5wt.%, the conductivity of protons from the anode to the cathode will be hindered; when the proportion of perfluorosulfonic acid resin is higher than 20wt.%, the thickness of the membrane material will increase, and the mass transfer resistance will increase accordingly, affecting the electrochemical performance of the battery.

[0060] The proportion of the perfluorosulfonic acid resin may be 5 wt.%, 10 wt.%, 15 wt.% or 20 wt.%.

[0061] The second aspect of the present invention provides a method for preparing the hydroxyl radical elimination layer, wherein the slurry is coated on a substrate and then dried to obtain the hydroxyl radical elimination layer.

[0062] The preparation method provided by the invention has simple process, is easy to operate and can realize industrial production.

[0063] It should be noted that the substrate in the present invention is not specifically limited, and it is required that the substrate does not react with the slurry and has a flat and smooth surface. The substrate is only used to provide physical support for the slurry and to form a coating after drying. For example, it can be glass, ceramic, metal sheet, PVC, PE, PET or Nafion.

[0064] Furthermore, the coating method includes spraying, slit coating or screen printing.

[0065] Preferably, the drying temperature is 50°C-70°C.

[0066] Typically, but not limiting, the drying temperature is 50°C, 55°C, 60°C, 65°C or 70°C.

[0067] The third aspect of the present invention provides the use of the hydroxyl radical elimination layer in a membrane electrode.

[0068] The application of the hydroxyl radical elimination layer provided by the present invention in the membrane electrode effectively reduces the free radical concentration in the proton exchange membrane, thereby reducing the degradation of the proton exchange membrane structure, increasing the life of the proton exchange membrane, and thereby increasing the life of the membrane electrode.

[0069] A fourth aspect of the present invention provides a membrane electrode, comprising a proton exchange membrane, an anode and cathode catalyst layers, and an cathode and cathode gas diffusion layers;

[0070] The hydroxyl radical elimination layer is arranged on at least one surface of the proton exchange membrane.

[0071] The membrane electrode provided by the present invention uses a better hydroxyl radical scavenger. In view of the beneficial effects of the above-mentioned hydroxyl radical scavenging layer, the membrane electrode has a better effect, expands the application scenarios of the membrane electrode, and promotes the development of downstream industries.

[0072] Furthermore, the hydroxyl radical elimination layer is located on a side close to the anode catalyst layer.

[0073] Preferably, the thickness of the hydroxyl radical elimination layer is 1 μm-5 μm.

[0074] In a first embodiment of the present invention, the structure of the membrane electrode is as follows Figure 1 As shown, it includes a proton exchange membrane 10, a cathode catalyst layer 20, a cathode gas diffusion layer 30, an anode catalyst layer 50, and an anode gas diffusion layer 60.

[0075] A cathode catalyst layer 20 and an anode catalyst layer 50 are respectively arranged on the left and right sides of the proton exchange membrane 10, and an anode gas diffusion layer 60 is arranged on the outside of the anode catalyst layer 50 and away from the proton exchange membrane 10; a cathode gas diffusion layer 30 is arranged on the outside of the cathode catalyst layer 20 and away from the proton exchange membrane 10.

[0076] The hydroxyl radical elimination layer 40 is disposed on the proton exchange membrane 10 .

[0077] The hydroxyl radical scavenging layer 40 is disposed on a side close to the anode catalyst layer 50 .

[0078] In a second embodiment of the present invention, the structure of the membrane electrode is as follows Figure 2 As shown, different from the first embodiment, the hydroxyl radical elimination layer 40 is arranged on a side close to the cathode catalyst layer 20.

[0079] In a third embodiment of the present invention, the structure of the membrane electrode is as follows Figure 3 As shown, different from the first embodiment, a first hydroxyl radical elimination layer 42 and a second hydroxyl radical elimination layer 44 are provided on the proton exchange membrane 10 .

[0080] The first hydroxyl radical elimination layer 42 is disposed on a side close to the anode catalyst layer 50 , and the second hydroxyl radical elimination layer 44 is disposed on a side close to the cathode catalyst layer 20 .

[0081] It should be noted that Figure 1 , Figure 2 and Figure 3 Each layer is only used to describe the relative position relationship and does not represent the thickness or the size relationship of the thickness.

[0082] Furthermore, the hydroxyl radical elimination layer is formed by coating on the proton exchange membrane through a transfer method, a direct coating method or a spray coating method.

[0083] The present invention is further described below by specific examples and comparative examples, but it should be understood that these examples are only used for more detailed description and should not be understood as limiting the present invention in any form. The raw materials used in the examples and comparative examples of the present invention, if no specific conditions are specified, are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially.

[0084] The NZP-Ce or ZP-Ce used in the embodiments of the present invention and the comparative examples are homemade products, and the preparation process is as follows: NZP (Hubei Langbowan Biotechnology Co., Ltd.) or ZP (13772-29-7, Hubei Langbowan Biotechnology Co., Ltd.) is prepared into a suspension solution with a mass concentration of 20%, CeO2 is added to the suspension solution and a high-temperature reaction is carried out, the reaction temperature is 180°C, and the reaction time is 24h. Finally, the solution is washed and filtered, and the filtered substance is dried at 80°C to obtain NZP-Ce or ZP-Ce powder.

[0085] Example 1

[0086] This embodiment provides a hydroxyl radical elimination layer, and the preparation method is as follows:

[0087] 1. In a stirrer, 14 g of NZP-Ce particles were mixed with 58 g of ultrapure water, and then 7 g of ethanol and 21 g of Nafion solution (mass percent concentration of 20%) were added in sequence.

[0088] 2. The stirrer continued stirring at a speed of 400 rpm. After stirring for 5 hours, a uniform and stable slurry was formed.

[0089] 3. Use spraying equipment to evenly coat the slurry on the Nafion membrane. After coating, place the Nafion membrane in an oven at 60°C until it is completely dried to obtain the Nafion / NZP-Ce membrane material.

[0090] Example 2

[0091] This embodiment provides a hydroxyl radical elimination layer. The difference from Embodiment 1 is that ZP-Ce particles are used to replace NZP-Ce particles. The remaining raw materials and methods are the same as those in Embodiment 1 and will not be described again.

[0092] Example 3

[0093] This embodiment provides a hydroxyl radical elimination layer, and the preparation method is as follows:

[0094] 1. In a stirrer, 10 g of NZP-Ce particles were mixed with 50 g of ultrapure water, and then 3 g of ethanol and 10 g of Nafion solution (mass percentage concentration of 20%) were added in sequence.

[0095] Step 2 and step 3 are the same as those in Example 1 and will not be described in detail here.

[0096] Example 4

[0097] This embodiment provides a hydroxyl radical elimination layer, and the preparation method is as follows:

[0098] 1. Mix 20 g of NZP-Ce particles and 65 g of ultrapure water in a stirrer, and then add 12 g of ethanol and 30 g of Nafion solution (mass percentage concentration is 20%) in sequence.

[0099] Step 2 and step 3 are the same as those in Example 1 and will not be described in detail here.

[0100] Example 5

[0101] This embodiment provides a hydroxyl radical elimination layer, and the preparation method is as follows:

[0102] 1. In a stirrer, 13 g of NZP-Ce particles were mixed with 56 g of ultrapure water, and then 5 g of ethanol and 13 g of Nafion solution (mass percentage concentration of 20%) were added in sequence.

[0103] Step 2 and step 3 are the same as those in Example 1 and will not be described in detail here.

[0104] Example 6

[0105] This embodiment provides a hydroxyl radical elimination layer, and the preparation method is as follows:

[0106] 1. In a stirrer, 17 g of NZP-Ce particles were mixed with 60 g of ultrapure water, and then 10 g of ethanol and 26 g of Nafion solution (mass percentage concentration of 20%) were added in sequence.

[0107] Step 2 and step 3 are the same as those in Example 1 and will not be described in detail here.

[0108] Example 7

[0109] This embodiment provides a hydroxyl radical elimination layer. The difference from Embodiment 1 is that the amount of NZP-Ce particles used is 15 g, and the other raw materials and methods are the same as those in Embodiment 1, which will not be repeated here.

[0110] Example 8

[0111] This embodiment provides a hydroxyl radical elimination layer. The difference from Embodiment 1 is that the amount of NZP-Ce particles used is 30 g, and the other raw materials and methods are the same as those in Embodiment 1, which will not be repeated here.

[0112] Comparative Example 1

[0113] This comparative example provides a hydroxyl radical elimination layer. The difference from Example 1 is that CeO2 particles are used to replace NZP-Ce particles. The remaining raw materials and methods are the same as those in Example 1 and will not be repeated here.

[0114] Examples 9-16

[0115] These embodiments provide membrane electrodes, wherein the Nafion / NZP-Ce or Nafion / ZP-Ce membrane materials and anode and cathode catalyst layers obtained in accordance with embodiments 1-8 are transferred into Nafion / NZP-Ce CCM or Nafion / ZP-Ce CCM, and then hot-pressed with a frame membrane and a gas diffusion layer to form a Nafion / NZP-Ce membrane electrode or a Nafion / ZP-Ce membrane electrode.

[0116] Comparative Example 2

[0117] This comparative example provides a membrane electrode, wherein the Nafion / CeO2 membrane material and the anode and cathode catalyst layers obtained in comparative example 1 are transferred into Nafion / CeO2 CCM, and then hot-pressed with a frame membrane and a gas diffusion layer to form a Nafion / CeO2 membrane electrode.

[0118] Test Example 1

[0119] The membrane electrodes obtained in Examples 9-16 and Comparative Example 2 were subjected to life evaluation tests.

[0120] The test process is: under the conditions of battery temperature of 90°C and humidity of 30%, the membrane electrodes obtained in Examples 9-16 and Comparative Example 2 are subjected to OCV cycles for 500 hours, and the voltage decay rate is calculated. The obtained data are shown in Table 1 below.

[0121] Table 1

[0122] Voltage attenuation rate / % Example 9 3.0 Example 10 3.3 Embodiment 11 3.1 Example 12 3.0 Example 13 3.4 Embodiment 14 3.2 Embodiment 15 3.3 Example 16 3.1 Comparative Example 2 10

[0123] It can be seen from Table 1 that coating the Nafion membrane with NZP-Ce or ZP-Ce improved OH radical scavenger can further improve the life of the membrane.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hydroxyl radical elimination layer, characterized in that: Made from a slurry containing a hydroxyl radical scavenger; The hydroxyl radical scavenger includes NZP-Ce and / or ZP-Ce.

2. The hydroxyl radical scavenging layer according to claim 1, characterized in that The slurry also includes water, alcohol and perfluorosulfonic acid resin solution; Preferably, the alcohol comprises at least one of ethanol, ethylene glycol, n-propanol, isopropanol and glycerol; Preferably, the water includes deionized water, distilled water and ultrapure water, preferably ultrapure water.

3. The hydroxyl radical scavenging layer according to claim 2, characterized in that: In terms of weight, the slurry includes 10-20 parts of a hydroxyl radical scavenger, 50-65 parts of water, 3-12 parts of an alcohol, and 10-30 parts of a perfluorosulfonic acid resin solution; Preferably, in parts by weight, the slurry comprises 13-17 parts of hydroxyl radical scavenger, 56-60 parts of water, 5-10 parts of alcohol and 13-26 parts of perfluorosulfonic acid resin solution.

4. The hydroxyl radical scavenging layer according to claim 2, characterized in that: In the perfluorosulfonic acid resin solution, the perfluorosulfonic acid resin accounts for 5wt.%-20wt.%.

5. A method for preparing the hydroxyl radical elimination layer according to any one of claims 1 to 4, characterized in that: The slurry is coated on a substrate and then dried to obtain the hydroxyl radical elimination layer.

6. The preparation method according to claim 5, characterized in that: The coating method includes spraying, slot coating or screen printing; Preferably, the drying temperature is 50°C-70°C.

7. Use of the hydroxyl radical elimination layer according to any one of claims 1 to 4 in a membrane electrode.

8. A membrane electrode, characterized in that: It includes a proton exchange membrane, an anode and cathode catalyst layers, and an anode and cathode gas diffusion layers; At least one surface of the proton exchange membrane is provided with the hydroxyl radical elimination layer according to any one of claims 1 to 4.

9. The membrane electrode according to claim 8, characterized in that: The hydroxyl radical elimination layer is arranged on a side close to the anode catalyst layer; Preferably, the thickness of the hydroxyl radical elimination layer is 1 μm-5 μm.

10. The membrane electrode according to claim 8, characterized in that: The hydroxyl radical elimination layer is formed by coating on the proton exchange membrane through a transfer method, a direct coating method or a spray coating method.

Images