Modified proton exchange membrane, preparation method thereof, membrane electrode, fuel cell and application

Abstract

The invention relates to the technical field of fuel cells, in particular to a modified proton exchange membrane, a preparation method thereof, a membrane electrode, a fuel cell and application. The preparation method of the modified proton exchange membrane provided by the invention comprises the following steps: performing first soaking treatment on a proton exchange membrane in a first solution of H2O2, and performing second soaking treatment on the proton exchange membrane in a second solution of H2SO4 to prepare a modified intermediate; performing third soaking treatment on the modified intermediate in a third solution of ionic liquid to prepare a modified proton exchange membrane; wherein cations of the ionic liquid are selected from one or more of structures as shown in a formula (I-1)-a formula (I-2); anions of the ionic liquid are selected from one or more of structures as shown in formulas (II-1)-(II-2). According to the modified proton exchange membrane prepared by the preparation method, the problem that the conductivity is reduced under a low-humidity condition can be improved, so that the performance of a membrane electrode can be ensured.

Description

Technical Field

[0001] The present application relates to the field of fuel cell technology, and in particular to a modified proton exchange membrane and a preparation method thereof, a membrane electrode, a fuel cell and applications thereof. Background Art

[0002] Proton exchange membrane fuel cell (PEMFC) is a power generation device that can convert chemical energy into electrical energy without combustion. Its advantages include: high conversion efficiency, no emission of harmful gases, high operating quality, low operating temperature, fast starting speed, simple structure, high specific power, easy operation, etc. Therefore, it is considered to be the preferred energy supply method for electric vehicles.

[0003] Proton exchange membrane is the core of fuel cells. The performance of proton exchange membrane directly affects the performance, energy conversion efficiency and service life of fuel cells. The proton exchange membrane currently used is easy to dehydrate under low humidity conditions, making it have low conductivity, which seriously affects the performance of the battery. Summary of the invention

[0004] Based on this, it is necessary to provide a modified proton exchange membrane and its preparation method, membrane electrode, fuel cell and application for the above technical problems. The modified proton exchange membrane prepared by the preparation method of the present application can improve the problem of reduced conductivity under low humidity conditions, thereby ensuring the performance of the membrane electrode.

[0005] In a first aspect of the present application, a method for preparing a modified proton exchange membrane is provided, comprising the following steps:

[0006] The proton exchange membrane is subjected to a first soaking treatment in a first solution of H2O2 and a second soaking treatment in a second solution of H2SO4 to prepare a modified intermediate;

[0007] performing a third immersion treatment on the modified intermediate in a third solution of ionic liquid to prepare the modified proton exchange membrane;

[0008] Wherein, the cation of the ionic liquid is selected from one or more structures represented by formula (I-1) to formula (I-2):

[0009] , , R 11 and R 12 Each is independently a C1~C6 alkyl;

[0010] The anion of the ionic liquid is selected from one or more structures represented by formula (II-1) to formula (II-3):

[0011] , , .

[0012] In one embodiment, the cation of the ionic liquid is selected from When the anion of the ionic liquid is selected from or ;

[0013] The cation of the ionic liquid is selected from When the anion of the ionic liquid is selected from , or .

[0014] In one embodiment, the first immersion treatment has one or more of the following characteristics:

[0015] (1) The temperature of the first immersion treatment is 60°C to 100°C;

[0016] (2) The first immersion treatment time is 0.5h~24h.

[0017] In one embodiment, the first solution of H2O2 has one or more of the following characteristics:

[0018] (1) The volume fraction of the first H2O2 solution is 1% to 10%;

[0019] (2) The solvent included in the first solution of H2O2 is water.

[0020] In one embodiment, the second soaking treatment has one or more of the following characteristics:

[0021] (1) The temperature of the second immersion treatment is 60°C to 100°C;

[0022] (2) The second immersion treatment time is 0.5h~24h.

[0023] In one embodiment, the second solution of H2SO4 has one or more of the following characteristics:

[0024] (1) The molar concentration of the second H2SO4 solution is 0.1 mol / L to 5 mol / L;

[0025] (2) The solvent included in the second solution of H2SO4 is water.

[0026] In one embodiment, the third immersion treatment has one or more of the following characteristics:

[0027] (1) The temperature of the third immersion treatment is 20°C to 40°C;

[0028] (2) The third immersion treatment time is 10 min to 30 min.

[0029] In one embodiment, the third solution of the ionic liquid has one or more of the following characteristics:

[0030] (1) The molar concentration of the third solution of the ionic liquid is 0.05 mol / L to 0.5 mol / L;

[0031] (2) The solvent included in the third solution of the ionic liquid is water.

[0032] In one embodiment, the first soaking treatment, the second soaking treatment and the third soaking treatment are each independently followed by a washing step.

[0033] The second aspect of the present application provides a modified proton exchange membrane prepared by the preparation method described in any embodiment of the first aspect of the present application.

[0034] The third aspect of the present application provides a membrane electrode, comprising an anode catalyst layer, a proton exchange membrane and a cathode catalyst layer stacked in sequence; the proton exchange membrane is the proton exchange membrane described in the second aspect of the present application.

[0035] A fourth aspect of the present application provides a fuel cell, comprising the membrane electrode described in the third aspect of the present application.

[0036] The preparation method of the modified proton exchange membrane provided in the present application has at least the following beneficial effects:

[0037] In the preparation method provided by the present application, the proton exchange membrane is firstly subjected to a first soaking treatment in a first solution of H2O2. This pretreatment step can remove organic impurities remaining in the preparation process of the proton exchange membrane, such as unreacted polymer monomers or free radicals, to remove impurities in the proton exchange membrane. Further assisted by a second soaking treatment in a second solution of H2SO4, it can further remove impurities such as metal oxides or alkaline functional groups present in the proton exchange membrane. The first soaking treatment and the second soaking treatment cooperate with each other to effectively reduce the impurity content in the proton exchange membrane, thereby improving the conductivity of the proton membrane.

[0038] The modified intermediate is further subjected to a third soaking treatment in a third solution of a specific type of ionic liquid. At this time, the cations in the ionic liquid can replace the protons in the exchange membrane to play a plasticizing role. On the other hand, after the cations in the ionic liquid replace the protons in the exchange membrane, the modified proton exchange membrane can have good thermal stability and reduce the swelling effect of water on ions. This allows the proton membrane to maintain good conductivity under conditions of low water content, thereby ensuring the performance of the membrane electrode. In addition, the presence of anions in the ionic liquid can maintain the electrically neutral environment of the proton exchange membrane to ensure the conduction mode and conduction rate of the protons.

[0039] In addition, the preparation method provided in the present application is simple to operate and suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a test diagram of polarization curves when the CCM prepared in Examples 1 to 3 and Comparative Examples 1 to 4 of the present application is applied to membrane electrodes. DETAILED DESCRIPTION

[0041] The modified proton exchange membrane and its preparation method, membrane electrode, fuel cell and application of the present application are further described in detail below in conjunction with specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0042] The term "alkyl" refers to a saturated hydrocarbon group containing primary (normal) carbon atoms, or secondary carbon atoms, or tertiary carbon atoms, or quaternary carbon atoms, or a combination thereof. Phrases containing this term, for example, "C1~C6 alkyl" refers to an alkyl group containing 1 to 6 carbon atoms, and each occurrence can be independently C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl or C6 alkyl. Suitable examples include, but are not limited to: methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1-propyl (n-propyl, n-Pr, n-propyl, -CH2CH2CH3), 2-propyl (i-Pr, i-propyl, -CH(CH3)2), 1-butyl (n-butyl, n-Bu, n-butyl, -CH2CH2CH2CH3), 2-methyl-1-propyl (i-Bu, i-butyl, -CH2CH(CH3)2), 2-butyl (s-Bu, s-butyl, - CH(CH3)CH2CH3), tert-butyl (1,1-dimethylethyl, 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH3)3), 1-pentyl (n-pentyl, n-pentyl, -CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH( CH3)2), 3-methyl-1-butyl (-CH2CH2CH(CH3)2), 2-methyl-1-butyl (-CH2CH(CH3)CH2CH3), 1-hexyl (n-hexyl, -CH2CH2CH2CH2CH2CH3), 2-hexyl (-CH(CH3)CH2CH2CH2CH3), 3-hexyl (-CH(CH2CH3)(CH2CH2CH3)), 2-methyl-2-pentyl (-C(CH3)2CH2CH2CH3), 3- Methyl-2-pentyl (-CH(CH3)CH(CH3)CH2CH3), 4-methyl-2-pentyl (-CH(CH3)CH2CH(CH3)2), 3-methyl-3-pentyl (-C(CH3)(CH2CH3)2), 2-methyl-3-pentyl (-CH(CH2CH3)CH(CH3)2), 2,3-dimethyl-2-butyl (-C(CH3)2CH(CH3)2), 3,3-dimethyl-2-butyl (-CH(CH3)C(CH3)3.

[0043] Proton exchange membrane fuel cells are an efficient, pollution-free power source that can provide higher energy density and energy efficiency. In proton exchange membrane fuel cells, the proton exchange membrane is the core component that conducts protons and plays the role of conducting protons and blocking reactive gases. However, traditional proton exchange membranes are easily dehydrated under low humidity conditions, resulting in lower conductivity, which can seriously affect the performance of the battery.

[0044] At present, there are mainly the following methods for modifying proton exchange membranes: (1) soaking the porous aromatic skeleton material in a first phosphoric acid solution to load phosphoric acid once, thereby obtaining a porous aromatic skeleton material loaded with phosphoric acid; then mixing the porous aromatic skeleton material loaded with phosphoric acid with polybenzimidazole in a solvent to obtain a casting solution; using the casting solution to form a membrane to obtain a modified polybenzimidazole membrane; soaking the modified polybenzimidazole membrane in a second phosphoric acid solution to load phosphoric acid twice to obtain a proton exchange membrane. This modification method prepares a proton membrane by recasting the raw material solution of the proton membrane and immersing it in an acid solution. The preparation process is cumbersome and the process is complicated. (2) preparing an antioxidant, a water retaining agent or a mixture with antioxidant and water retaining functions; using a coating device to coat the obtained mixed solution on both sides of the microporous reinforced membrane, and after drying, preparing a modified perfluorosulfonic acid proton exchange membrane; and preparing a fuel cell membrane electrode with the modified PEM membrane. This preparation method is similar to the first preparation method, both of which involve recasting the raw material solution of the proton membrane. (3) Casting a resin solution on one or both sides of the proton exchange membrane to form a resin raw material layer with proton conductivity; then, the resin raw material layer is micro-nano-imprinted and structurally replicated using a template. This modification method also requires the manufacture of a mold specifically for low-temperature imprinting, which increases the manufacturing cost, and this method has limited effect on improving the proton transfer rate under low humidity.

[0045] Based on this, the first aspect of the present application provides a method for preparing a modified proton exchange membrane, comprising the following steps:

[0046] The proton exchange membrane is subjected to a first soaking treatment in a first solution of H2O2 and a second soaking treatment in a second solution of H2SO4 to prepare a modified intermediate;

[0047] performing a third immersion treatment on the modified intermediate in a third solution of ionic liquid to prepare the modified proton exchange membrane;

[0048] Wherein, the cation of the ionic liquid is selected from one or more structures represented by formula (I-1) to formula (I-2):

[0049] , , R 11 and R 12 Each is independently a C1~C6 alkyl;

[0050] The anion of the ionic liquid is selected from one or more structures represented by formula (II-1) to formula (II-3):

[0051] , , .

[0052] In the preparation method provided by the present application, the proton exchange membrane is firstly subjected to a first soaking treatment in a first solution of H2O2. This pretreatment step can remove organic impurities remaining in the preparation process of the proton exchange membrane, such as unreacted polymer monomers or free radicals, to remove impurities in the proton exchange membrane. Further assisted by a second soaking treatment in a second solution of H2SO4, it can further remove impurities such as metal oxides or alkaline functional groups present in the proton exchange membrane. The first soaking treatment and the second soaking treatment cooperate with each other to effectively reduce the impurity content in the proton exchange membrane, thereby improving the conductivity of the proton membrane.

[0053] The modified intermediate is further subjected to a third soaking treatment in a third solution of a specific type of ionic liquid. At this time, the cations in the ionic liquid can replace the protons in the exchange membrane to play a plasticizing role. On the other hand, after the cations in the ionic liquid replace the protons in the exchange membrane, the modified proton exchange membrane can have good thermal stability and reduce the swelling effect of water on ions. This allows the proton membrane to maintain good conductivity under conditions of low water content, thereby ensuring the performance of the membrane electrode. In addition, the presence of anions in the ionic liquid can maintain the electrically neutral environment of the proton exchange membrane to ensure the conduction mode and conduction rate of the protons.

[0054] In addition, the preparation method provided in the present application is simple to operate and suitable for mass production.

[0055] For example, the cation of the ionic liquid is selected from , , , , and One or more of .

[0056] In one example, the cation of the ionic liquid is selected from When the anion of the ionic liquid is selected from or .

[0057] In one example, the cation of the ionic liquid is selected from When the anion of the ionic liquid is selected from , or .

[0058] The present application has found that the cations and anions of the above-mentioned specific structure can better play a synergistic role. At this time, the cations in the ionic liquid can be exchanged with the protons in the proton exchange membrane, thereby ensuring the mechanical properties of the modified proton exchange membrane. Further synergizing the anions in the ionic liquid, this plays an important role in maintaining the electrically neutral environment of the modified proton exchange membrane and ensuring the conduction rate of the modified proton exchange membrane. Further, after being soaked in the ionic liquid solution of the above-mentioned specific structure, the prepared modified proton exchange membrane can still maintain good conductivity under the condition of low water content, thereby helping to improve the performance of the membrane electrode.

[0059] In one example, the process parameters of the first immersion treatment include: the temperature of the first immersion treatment is 60° C. to 100° C. For example, the temperature of the first immersion treatment includes but is not limited to 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., 95° C. or 100° C., or a range formed by any two of the above point values ​​as end values.

[0060] In one example, the process parameters of the first immersion treatment include: the time of the first immersion treatment is 0.5h~24h. For example, the time of the first immersion treatment includes but is not limited to 0.5h, 1h, 2h, 5h, 10h, 15h, 20h, 22h or 24h, or a range formed by any two of the above point values ​​as end values.

[0061] In one example, the volume fraction of the first H2O2 solution is 1% to 10%. For example, the volume fraction of the H2O2 aqueous solution includes, but is not limited to, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, or a range consisting of any two of the above points as end values.

[0062] In one example, the solvent included in the first solution of H2O2 is water.

[0063] The temperature and time of the first immersion treatment and the volume fraction of the first H2O2 solution are important for ensuring the oxidative activity of H2O2, decomposing unreacted polymer monomers or free radicals, etc., so as to improve the impurity removal efficiency of the proton exchange membrane and avoid excessive oxidation from damaging the main structure of the proton exchange membrane.

[0064] In one example, the process parameters of the second immersion treatment include: the temperature of the second immersion treatment is 60° C. to 100° C. For example, the temperature of the second immersion treatment includes but is not limited to 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., 95° C. or 100° C., or a range formed by any two of the above point values ​​as end values.

[0065] In one example, the process parameters of the second immersion treatment include: the time of the second immersion treatment is 0.5h~24h. For example, the time of the second immersion treatment includes but is not limited to 0.5h, 1h, 2h, 5h, 10h, 15h, 20h, 22h or 24h, or a range formed by any two of the above point values ​​as end values.

[0066] In one example, the molar concentration of the second solution of H2SO4 is 0.1 mol / L to 5 mol / L. For example, the molar concentration of the second solution of H2SO4 includes, but is not limited to, 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 0.7 mol / L, 0.9 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.5 mol / L, 2.8 mol / L, 3 mol / L, 3.2 mol / L, 3.5 mol / L, 3.8 mol / L, 4 mol / L, 4.2 mol / L, 4.5 mol / L, 4.8 mol / L or 5 mol / L, or a range consisting of any two of the above point values ​​as end values.

[0067] The solvent included in the second solution of H2SO4 is water.

[0068] Limiting the temperature and time of the soaking treatment can provide suitable reaction conditions for the chemical reaction between the impurities such as metals or metal oxides in the proton exchange membrane and sulfuric acid. At the same time, using sulfuric acid for the second soaking treatment can obtain a hydrogen-type proton exchange membrane, which is easier to perform the third soaking treatment with the ionic liquid.

[0069] In one example, the process parameters of the third immersion treatment include: the temperature of the third immersion treatment is 20° C. to 40° C. For example, the temperature of the third immersion treatment includes but is not limited to 20° C., 22° C., 25° C., 28° C., 30° C., 32° C., 35° C., 38° C. or 40° C., or a range formed by any two of the above point values ​​as endpoint values.

[0070] In one example, the process parameters of the third immersion treatment include: the time of the third immersion treatment is 10 min to 30 min. For example, the time of the third immersion treatment includes but is not limited to 10 min, 12 min, 14 min, 15 min, 16 min, 18 min, 20 min, 22 min, 25 min, 28 min or 30 min.

[0071] In one example, the molar concentration of the third solution of the ionic liquid is 0.05 mol / L to 0.5 mol / L. For example, the molar concentration of the third solution of the ionic liquid includes but is not limited to 0.05 mol / L, 0.07 mol / L, 0.09 mol / L, 0.1 mol / L, 0.11 mol / L, 0.15 mol / L, 0.18 mol / L, 0.2 mol / L, 0.22 mol / L, 0.25 mol / L, 0.28 mol / L, 0.3 mol / L, 0.33 mol / L, 0.35 mol / L, 0.38 mol / L, 0.4 mol / L, 0.45 mol / L, 0.48 mol / L or 0.5 mol / L.

[0072] In one example, the solvent included in the third solution of ionic liquid is water.

[0073] The concentration of ionic liquid affects the proton conduction performance of the proton exchange membrane. Ensuring the concentration of ionic liquid can make the cations in the ionic liquid effectively replace the protons in the exchange membrane to ensure the mechanical properties of the proton exchange membrane and increase the number of proton conduction sites.

[0074] In one example, the proton exchange membrane includes one or more of a Nafion membrane, a Gore-select membrane, and a Flemion membrane.

[0075] In one example, after the first soaking treatment, the second soaking treatment and the third soaking treatment, a washing step is independently included. It is understandable that the present application does not limit the washing liquid and washing method in the washing step. For example, the washing liquid includes but is not limited to water. The washing method includes but is not limited to rinsing.

[0076] In one specific example, the method for preparing the modified proton exchange membrane comprises the following steps:

[0077] S100, subjecting the proton exchange membrane to a first immersion treatment in a H2O2 aqueous solution having a volume fraction of 1% to 10% for 0.5 h to 24 h, wherein the temperature of the first immersion treatment is 60°C to 100°C.

[0078] S200, performing a second immersion treatment in a H2SO4 aqueous solution with a molar concentration of 0.1 mol / L to 5 mol / L for 0.5 h to 24 h, the temperature of the second immersion treatment being 60°C to 100°C, to prepare a modified intermediate.

[0079] S300, subjecting the modified intermediate to a third immersion treatment in an ionic liquid aqueous solution with a molar concentration of 0.05 mol / L to 0.5 mol / L for 10 min to 30 min, wherein the temperature of the third immersion treatment is 20° C. to 40° C. to prepare the modified proton exchange membrane.

[0080] In a second aspect of the present application, a modified proton exchange membrane is provided, which is prepared by the preparation method described in any example of the first aspect of the present application.

[0081] The third aspect of the present application provides a membrane electrode, comprising an anode catalyst layer, a proton exchange membrane and a cathode catalyst layer stacked in sequence; the proton exchange membrane is the proton exchange membrane described in the second aspect of the present application.

[0082] In one example, the membrane electrode further comprises an anode gas diffusion layer and a cathode gas diffusion layer. It can be understood that the anode gas diffusion layer is arranged close to the anode catalyst layer, and the cathode gas diffusion layer is arranged close to the cathode gas diffusion layer.

[0083] The present application also provides a method for preparing a membrane electrode, comprising the following steps:

[0084] The anode catalyst layer slurry and the cathode catalyst layer slurry are respectively applied to two opposite surfaces of the proton exchange membrane, and after drying, the membrane electrode is prepared. For example, the coating method of the anode catalyst layer slurry and the cathode catalyst layer slurry on the surface of the proton exchange membrane includes but is not limited to ultrasonic spraying, direct coating or transfer printing.

[0085] A fourth aspect of the present application provides a fuel cell, comprising the membrane electrode described in the third aspect of the present application.

[0086] The following further specific examples are provided to explain the present application in detail. It should also be understood that the following examples are only used to further explain the present application and cannot be understood as limiting the scope of protection of the present application. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present application belong to the scope of protection of the present application. The specific process parameters of the following embodiments are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not necessarily limited to the specific values ​​of the embodiments below.

[0087] Example 1

[0088] Preparation of modified proton exchange membrane:

[0089] (1) A proton exchange membrane (Nafion 117, purchased from Dupont) was immersed in a 5% by volume H2O2 aqueous solution for 1 hour at a temperature of 80°C. After the first immersion, the proton exchange membrane was taken out and rinsed with ultrapure water for later use.

[0090] (2) Perform a second soaking treatment in a H2SO4 aqueous solution with a molar concentration of 0.5 mol / L to 5 mol / L for 1 hour at a temperature of 80°C to prepare a modified intermediate. Rinse the modified intermediate with ultrapure water and set aside.

[0091] (3) The modified intermediate after washing was subjected to a third soaking treatment in an ionic liquid aqueous solution with a molar concentration of 0.1 mol / L for 15 min at a temperature of 25° C. to prepare a modified proton exchange membrane. The ionic liquid included in the ionic liquid solution is [BMIM][BF4], and its corresponding cation structure is , the anion structure is .

[0092] Preparation of catalyst-coated proton exchange membrane (CCM): (1) Pt / C catalyst (Pt mass fraction is 60%, model: JM9100) and ionomer dispersion (ionomer mass fraction in ionomer dispersion is 5%, model: D520, purchased from DuPont) are added to an isopropanol-water mixed solution (wherein the volume ratio of the isopropanol-water mixed solution is 1:3), and then oscillated and dispersed in an ultrasonic water bath for 3 hours to prepare a catalyst layer slurry. In the catalyst layer slurry, the mass volume ratio of the Pt / C catalyst is 10 mg / mL, and the mass fraction of the ionomer included in the ionomer dispersion is 30%.

[0093] (2) Under the operating condition of 100°C, the catalyst layer slurry was sprayed onto both sides of the modified proton exchange membrane using an ultrasonic spray device, where the platinum loading of the cathode catalyst layer was 0.4 mg / cm 2 The platinum loading of the cathode catalyst layer is 0.1 mg / cm 2 , CCM was prepared.

[0094] Example 2

[0095] Preparation of modified proton exchange membrane:

[0096] (1) A proton exchange membrane (Nafion 117, purchased from Dupont) was immersed in a 5% by volume H2O2 aqueous solution for 1 hour at a temperature of 80°C. After the first immersion, the proton exchange membrane was taken out and rinsed with ultrapure water for later use.

[0097] (2) Perform a second soaking treatment in a H2SO4 aqueous solution with a molar concentration of 0.5 mol / L to 5 mol / L for 1 hour at a temperature of 80°C to prepare a modified intermediate. Rinse the modified intermediate with ultrapure water and set aside.

[0098] (3) The modified intermediate after washing was subjected to a third soaking treatment in an ionic liquid aqueous solution with a molar concentration of 0.1 mol / L for 15 min at a temperature of 25° C. to prepare a modified proton exchange membrane. The ionic liquid included in the ionic liquid solution is [EMIM][NTF2], and its corresponding cation structure is , the anion structure is .

[0099] Preparation of CCM: (1) Pt / C catalyst (Pt mass fraction is 60%, model: JM9100) and ionomer dispersion (ionomer mass fraction in ionomer dispersion is 5%, model: D520, purchased from DuPont) are added to an isopropanol-water mixed solution (wherein the volume ratio of the isopropanol-water mixed solution is 1:3), and then oscillated and dispersed in an ultrasonic water bath for 3 hours to prepare a catalytic layer slurry. In the catalytic layer slurry, the mass volume ratio of the Pt / C catalyst is 10 mg / mL, and the mass fraction of the ionomer included in the ionomer dispersion is 30%.

[0100] (2) Under the operating condition of 100°C, the catalyst layer slurry was sprayed onto both sides of the modified proton exchange membrane using an ultrasonic spray device, where the platinum loading of the cathode catalyst layer was 0.4 mg / cm 2 The platinum loading of the cathode catalyst layer is 0.1 mg / cm 2 , CCM was prepared.

[0101] Example 3

[0102] Preparation of modified proton exchange membrane:

[0103] (1) A proton exchange membrane (Nafion 117, purchased from Dupont) was immersed in a 5% by volume H2O2 aqueous solution for 1 hour at a temperature of 80°C. After the first immersion, the proton exchange membrane was taken out and rinsed with ultrapure water for later use.

[0104] (2) Perform a second soaking treatment in a H2SO4 aqueous solution with a molar concentration of 0.5 mol / L to 5 mol / L for 1 hour at a temperature of 80°C to prepare a modified intermediate. Rinse the modified intermediate with ultrapure water and set aside.

[0105] (3) The modified intermediate after washing was subjected to a third soaking treatment in an ionic liquid aqueous solution with a molar concentration of 0.1 mol / L for 15 min at a temperature of 25° C. to prepare a modified proton exchange membrane. The ionic liquid included in the ionic liquid solution is [EMIM][NTF2], and its corresponding cation structure is , the anion structure is .

[0106] Preparation of CCM: (1) Pt / C catalyst (Pt mass fraction is 60%, model: JM9100) and ionomer dispersion (ionomer mass fraction in ionomer dispersion is 5%, model: D520, purchased from DuPont) are added to an isopropanol-water mixed solution (wherein the volume ratio of the isopropanol-water mixed solution is 1:3), and then oscillated and dispersed in an ultrasonic water bath for 3 hours to prepare a catalytic layer slurry. In the catalytic layer slurry, the mass volume ratio of the Pt / C catalyst is 10 mg / mL, and the mass fraction of the ionomer included in the ionomer dispersion is 30%.

[0107] (2) Under the operating condition of 100°C, the catalyst layer slurry was sprayed onto both sides of the modified proton exchange membrane using an ultrasonic spray device, where the platinum loading of the cathode catalyst layer was 0.4 mg / cm 2 The platinum loading of the cathode catalyst layer is 0.1 mg / cm 2 , CCM was prepared.

[0108] Comparative Example 1

[0109] Comparative Example 1 is substantially the same as Example 1, with the main difference being that in Comparative Example 1, the preparation of the modified proton exchange membrane does not include the step of performing a first immersion treatment in a H2O2 aqueous solution.

[0110] Comparative Example 2

[0111] Comparative Example 2 is substantially the same as Example 1, with the main difference being that in Comparative Example 2, the preparation of the modified proton exchange membrane does not include the step of performing a second immersion treatment in an aqueous H2SO4 solution.

[0112] Comparative Example 3

[0113] Comparative Example 3 is substantially the same as Example 1, with the main difference being that in Comparative Example 3, the preparation of the modified proton exchange membrane does not include the step of performing a third immersion treatment in an ionic liquid aqueous solution.

[0114] Comparative Example 4

[0115] Preparation of CCM: (1) Pt / C catalyst (Pt mass fraction is 60%, model: JM9100) and ionomer dispersion (ionomer mass fraction in ionomer dispersion is 5%, model: D520, purchased from DuPont) are added to an isopropanol-water mixed solution (wherein the volume ratio of the isopropanol-water mixed solution is 1:3), and then oscillated and dispersed in an ultrasonic water bath for 3 hours to prepare a catalytic layer slurry. In the catalytic layer slurry, the mass volume ratio of the Pt / C catalyst is 10 mg / mL, and the mass fraction of the ionomer included in the ionomer dispersion is 30%.

[0116] (2) Under the operating condition of 100°C, the catalyst layer slurry was sprayed onto both sides of the proton exchange membrane (Nafion 117, purchased from Dupont) using an ultrasonic spray device, where the platinum loading of the cathode catalyst layer was 0.4 mg / cm 2 The platinum loading of the cathode catalyst layer is 0.1 mg / cm 2 , CCM was prepared.

[0117] The CCM prepared in the examples and comparative examples was subjected to performance tests:

[0118] (1) The gas diffusion layers on both sides of the CCM of the embodiment and the comparative example were hot pressed at 0.1 MPa and 60°C for 10 s to prepare a membrane electrode.

[0119] (2) The membrane electrode after hot pressing was subjected to polarization curve test. The test conditions were: battery temperature 75°C, gas excess coefficient H2 / Air = 1.5 / 2, humidity 40%, pressure 0.1MPa. The test results are as follows: Figure 1 shown.

[0120] Depend on Figure 1 It can be seen that when the modified proton exchange membrane prepared in Example 1 of the present application is applied to a fuel cell membrane electrode, its performance is better than that of Comparative Examples 1 to 4. 2 At a current density of , the voltage value of the membrane electrode prepared in Example 1 of the present application is 0.685V, the voltage value of Comparative Example 1 which does not perform the first immersion treatment in the H2O2 aqueous solution is 0.679V, the voltage value of Comparative Example 2 which does not perform the immersion treatment in the H2SO4 aqueous solution is 0.672V, the voltage value of Comparative Example 3 which does not perform the third immersion treatment in the ionic liquid solution is 0.662V, and the voltage value of Comparative Example 4 which does not perform the immersion treatment in the H2O2 aqueous solution, the H2SO4 aqueous solution, and the ionic liquid aqueous solution is 0.652V, that is, the preparation method of Example 1 can make the fuel cell membrane electrode at 2000mA / cm 2This shows that in the preparation method of the present application, the modified proton exchange membrane prepared under the cooperation of the first immersion treatment, the second immersion treatment and the third immersion treatment can effectively improve the problem of reduced conductivity under low humidity conditions.

[0121] In addition, by Figure 1 It can be seen that when the modified proton exchange membranes prepared in Examples 1, 2 and 3 of the present application are treated with different types of ionic liquid solutions and applied to membrane electrodes, they have better voltage values, which indicates that the modified proton exchange membranes of Examples 2 and 3 have higher electrical conductivity under low humidity conditions.

[0122] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0123] The above-described embodiments only express several implementation methods of the present application, which is convenient for understanding the technical solution of the present application in detail, but it cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description can be used to interpret the content of the claims.

Claims

1. A method for preparing a modified proton exchange membrane, characterized in that: The following steps are involved: The proton exchange membrane is subjected to a first soaking treatment in a first solution of H2O2 and a second soaking treatment in a second solution of H2SO4 to prepare a modified intermediate; performing a third immersion treatment on the modified intermediate in a third solution of ionic liquid to prepare the modified proton exchange membrane; Wherein, the cation of the ionic liquid is selected from one or more structures shown in formula (I-1) to formula (I-2): , , R 11 and R 12 Each is independently a C1~C6 alkyl; The anion of the ionic liquid is selected from one or more structures represented by formula (II-1) to formula (II-3): 、 、 。 2. The method for preparing a modified proton exchange membrane according to claim 1, characterized in that: The cation of the ionic liquid is selected from When the anion of the ionic liquid is selected from or ; The cation of the ionic liquid is selected from When the anion of the ionic liquid is selected from , or .

3. The method for preparing a modified proton exchange membrane according to claim 1 or 2, characterized in that: The first immersion treatment has one or more of the following characteristics: (1) The temperature of the first immersion treatment is 60°C to 100°C; (2) The first immersion treatment time is 0.5h~24h.

4. The method for preparing a modified proton exchange membrane according to claim 3, characterized in that: The first solution of H2O2 has one or more of the following characteristics: (1) The volume fraction of the first H2O2 solution is 1% to 10%; (2) The solvent included in the first solution of H2O2 is water.

5. The method for preparing a modified proton exchange membrane according to claim 1 or 2, characterized in that: The second immersion treatment has one or more of the following characteristics: (1) The temperature of the second immersion treatment is 60°C to 100°C; (2) The second immersion treatment time is 0.5h~24h.

6. The method for preparing a modified proton exchange membrane according to claim 5, characterized in that: The second solution of H2SO4 has one or more of the following characteristics: (1) The molar concentration of the second H2SO4 solution is 0.1 mol / L to 5 mol / L; (2) The solvent included in the second solution of H2SO4 is water.

7. The method for preparing a modified proton exchange membrane according to claim 1 or 2, characterized in that: The third immersion treatment has one or more of the following characteristics: (1) The temperature of the third immersion treatment is 20°C to 40°C; (2) The third immersion treatment time is 10 min to 30 min.

8. The method for preparing a modified proton exchange membrane according to claim 7, characterized in that: The third solution of the ionic liquid has one or more of the following characteristics: (1) The molar concentration of the third solution of the ionic liquid is 0.05 mol / L to 0.5 mol / L; (2) The solvent included in the third solution of the ionic liquid is water.

9. The method for preparing a modified proton exchange membrane according to claim 1 or 2, characterized in that: After the first soaking treatment, the second soaking treatment and the third soaking treatment, each independently includes a washing step.

10. A modified proton exchange membrane, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 9.

11. A membrane electrode, characterized in that: It comprises an anode catalyst layer, a proton exchange membrane and a cathode catalyst layer stacked in sequence; the proton exchange membrane is the proton exchange membrane according to claim 10.

12. A fuel cell, characterized in that: Comprising the membrane electrode according to claim 11.

13. An electrical device, characterized in that: Comprising the fuel cell according to claim 12.

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