Cathode catalyst slurry introduced with serine polybenzimidazole and preparation method of cathode catalyst slurry
By introducing serine polybenzimidazole into the cathode catalyst layer and utilizing its cross-linking effect with phosphoric acid, the problems of phosphoric acid coverage and migration loss were solved, thereby improving the performance of high-temperature proton exchange membrane fuel cells.
Patent Information
- Application Number
- CN202511505339.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-21
- Publication Date
- 2026-02-10
AI Technical Summary
In traditional cathode catalyst layers, phosphoric acid covers Pt active sites, hindering the transport of reactive gases, and its migration and loss lead to a decline in battery performance.
Serine polybenzimidazole (SerPBI) was generated by condensation of serine and polybenzimidazole and introduced into the cathode catalyst layer. The hydroxyl groups of SerPBI were crosslinked with phosphoric acid at high temperature to fix phosphoric acid and reduce its adsorption and migration loss at Pt active sites.
It effectively reduces the adsorption of phosphoric acid on Pt active sites, improves the transport of reactant gases, and enhances the output power and stability of high-temperature proton exchange membrane fuel cells.
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Figure CN121506967A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of high-temperature proton exchange membrane fuel cell, in particular to a cathode catalyst slurry with serine polybenzimidazole and a preparation method thereof. BACKGROUND
[0002] Proton exchange membrane fuel cell (PEMFC) is a kind of high-efficiency energy conversion device, which has the advantages of high power density, environmental friendliness, renewable fuel and wide application range, so it has very broad application prospect. Proton exchange membrane fuel cell (PEMFC) is divided into low-temperature proton exchange membrane fuel cell (LT-PEMFC) mainly using Nafion membrane and high-temperature proton exchange membrane fuel cell (HT-PEMFC) mainly using phosphoric acid doped polybenzimidazole. The operation temperature of PEMFC is increased to more than 100 DEG C, which is called high-temperature proton exchange membrane fuel cell (HT-PEMFC), and the working temperature is generally 100-200 DEG C. Compared with the commercial low-temperature PEMFC, the high-temperature PEMFC has the advantages of simple water and heat management, strong CO poisoning resistance and high catalytic reaction activity.
[0003] Membrane electrode assembly (MEA) is the core component of high-temperature proton exchange membrane fuel cell (HT-PEMFC), and the catalytic layer in MEA plays an extremely important role in determining the performance of fuel cell as the place where chemical reaction occurs. The phosphoric acid in the traditional cathode catalyst layer will cover the active sites of the catalyst Pt, hindering the transmission of the reaction gas to the Pt active sites. In addition, the phosphoric acid in the traditional cathode catalyst layer will also migrate and lose from the catalyst layer, resulting in the performance degradation of the battery. SUMMARY
[0004] The purpose of the present application is to solve the problems of covering Pt active sites and migration loss of phosphoric acid in the traditional cathode catalyst layer, and a cathode catalyst slurry with serine polybenzimidazole and a preparation method thereof are provided.
[0005] In order to achieve the above purpose, the present application provides a preparation method of a cathode catalyst slurry with serine polybenzimidazole, comprising the following steps: Step 1: using serine and polybenzimidazole as reactants to undergo condensation reaction to obtain serine polybenzimidazole; Step 2: mixing the serine polybenzimidazole, the binder and the catalyst to obtain the cathode catalyst slurry with serine polybenzimidazole.
[0006] Optionally, the specific steps of step 1 are as follows: dissolving serine and polybenzimidazole in dimethyl sulfoxide solution, heating the solution to 90-100 DEG C, and reacting for 22-24 h to obtain the serine polybenzimidazole.
[0007] Optionally, the mass ratio of serine and polybenzimidazole is 1:(1-5).
[0008] Optionally, in step 2, the binder is polytetrafluoroethylene, and the catalyst is a platinum-based catalyst or a platinum-based alloy catalyst.
[0009] Optionally, in step 2, the mass ratio of serine polybenzimidazole and the binder is 1:(0.1-5).
[0010] Optionally, in step 2, the mass ratio of serine polybenzimidazole and the catalyst is 1:(5-20).
[0011] Optionally, the specific steps of step 2 are: Step 2.1, dispersing the binder in water and a surfactant solution to obtain a binder solution; Step 2.2, dispersing the catalyst in a solvent to obtain a catalyst solution; Step 2.3, mixing the serine polybenzimidazole, the binder solution and the catalyst solution to obtain the serine polybenzimidazole-introduced cathode catalyst slurry.
[0012] Optionally, the surfactant is FC-4430 or FC-003.
[0013] The application also provides a serine polybenzimidazole-introduced cathode catalyst slurry, which comprises an ionomer, a binder and a catalyst; the ionomer is serine polybenzimidazole, the binder is polytetrafluoroethylene, and the catalyst is a platinum-based catalyst or a platinum-based alloy catalyst.
[0014] The application also provides a proton exchange membrane fuel cell membrane electrode, which comprises a proton exchange membrane, a cathode catalyst layer and an anode catalyst layer, the cathode catalyst layer and the anode catalyst layer are arranged on the two sides of the proton exchange membrane, and the cathode catalyst layer is made of the above-mentioned cathode catalyst slurry.
[0015] Compared with the prior art, the application has the following beneficial effects: By introducing the ionomer serine polybenzimidazole into the cathode catalyst layer, the hydroxyl groups on the ionomer serine polybenzimidazole can be crosslinked with phosphoric acid under the high-temperature environment of the high-temperature proton exchange membrane fuel cell (HT-PEMFC), the phosphoric acid is fixed on the ionomer serine polybenzimidazole, the adsorption of phosphoric acid on the Pt active sites is reduced, the migration and loss of phosphoric acid in the cathode catalyst layer are reduced, the distribution of phosphoric acid in the catalyst layer is adjusted, the proton conduction of phosphoric acid is improved, and the output power and stability of the HT-PEMFC are improved. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1are polarization curves of the membrane electrode prepared from the catalyst slurry of Examples 1-3 and Comparative Examples.
[0017] Figure 2 are cyclic voltammograms of the membrane electrode prepared from the catalyst slurry of Examples 1-3 and Comparative Examples. DETAILED DESCRIPTION
[0018] The technical solutions of the present application are further described below in combination with the drawings and examples.
[0019] As described in the background, phosphoric acid in the conventional cathode catalyst layer of the membrane electrode covers the active sites of the catalyst Pt, hindering the transmission of gas to the Pt active sites. In addition, the phosphoric acid in the conventional cathode catalyst layer also migrates and loses from the catalyst layer, resulting in the degradation of battery performance.
[0020] To solve the problems of phosphoric acid covering the Pt active sites and migrating and losing in the conventional cathode catalyst layer, the present application condenses serine and polybenzimidazole (OPBI) to obtain ionomer serine polybenzimidazole (SerPBI), and introduces it into the cathode catalyst layer. Since the hydroxyl group of the ionomer SerPBI can crosslink with phosphoric acid under high temperature conditions, the phosphoric acid is fixed on the ionomer SerPBI, thereby effectively reducing the adsorption of phosphoric acid on the Pt active sites, reducing the migration and loss of phosphoric acid, and adjusting the distribution of phosphoric acid in the cathode catalyst layer.
[0021] Specifically, the present application provides a preparation method of a cathode catalyst slurry introducing serine polybenzimidazole, which comprises: Step 1: serine polybenzimidazole is obtained by condensation reaction using serine and polybenzimidazole as reactants. The reaction formula is as follows:
[0022] Step 2: the cathode catalyst slurry introducing serine polybenzimidazole is obtained by mixing the serine polybenzimidazole, a binder and a catalyst.
[0023] In some embodiments, the binder is polytetrafluoroethylene (PTFE), the surfactant is FC-4430 or FC-003, and the catalyst is a platinum-based catalyst (such as Pt / C) or a platinum alloy catalyst (such as PtCo / C).
[0024] A certain mass of serine polybenzimidazole is dissolved in dimethyl sulfoxide (DMSO) to obtain a serine polybenzimidazole solution. The serine polybenzimidazole solution is mixed with a binder solution and a catalyst solution to obtain the cathode catalyst slurry introducing serine polybenzimidazole.
[0025] In some embodiments, the mass ratio of serine polybenzimidazole to binder is 1:(0.1-5).
[0026] The technical solutions of the present application are further described below in combination with examples.
[0027] Example 1 The present example provides a preparation method of a cathode catalyst slurry introducing serine polybenzimidazole, which comprises: (1) Preparation of serine polybenzimidazole solution: 10 parts by mass of polybenzimidazole is dissolved in dimethyl sulfoxide to obtain a polybenzimidazole solution, the dissolution temperature is 60℃, and the dissolution time is 6h. Then 5 parts by mass of serine is added to the polybenzimidazole solution to undergo condensation reaction to obtain a serine polybenzimidazole solution, the reaction temperature is 100℃, and the reaction time is 24h.
[0028] (2) Preparation of catalyst slurry: A certain mass of polytetrafluoroethylene is dispersed in deionized water, and a certain mass of surfactant FC-4430 is dissolved in dimethyl sulfoxide to obtain a polytetrafluoroethylene solution. Then a certain mass of PtCo / C catalyst is dispersed in dimethyl sulfoxide to obtain a PtCo / C catalyst solution. Then 20 parts by mass of the polytetrafluoroethylene solution and 5 parts by mass of the serine polybenzimidazole solution are added to 100 parts by mass of the PtCo / C catalyst solution to obtain the cathode catalyst slurry introducing serine polybenzimidazole of the present example.
[0029] Example 2 The difference between the present example and Example 1 is that the serine polybenzimidazole solution is 10 parts by mass.
[0030] Example 3 The difference between the present example and Example 1 is that the serine polybenzimidazole solution is 15 parts by mass.
[0031] Example 4 The difference between the present example and Example 1 is that the polytetrafluoroethylene solution is 25 parts by mass.
[0032] Example 5 The difference between the present example and Example 1 is that the reaction temperature of serine and polybenzimidazole is 95℃.
[0033] Example 6 The present example provides a membrane electrode prepared by using the catalyst slurry of Example 1, and the preparation method is as follows: The catalyst slurry of Example 1 is uniformly sprayed onto the surface of the cathode gas diffusion layer using an ultrasonic spraying method, and the loading of the catalyst Pt is controlled at 0.4-0.6mg / cm 2, and the cathode gas diffusion electrode is obtained after drying. The polybenzimidazole proton exchange membrane and the anode gas diffusion electrode are hot-pressed on two sides of the polybenzimidazole proton exchange membrane respectively, and a membrane electrode is prepared. The active area of the membrane electrode is 4 cm 2 , the hot-pressing temperature is 160 DEG C, and the time is 6 min. The hot-pressed membrane electrode is placed in a constant temperature and humidity cabinet for storage.
[0034] The cathode gas diffusion layer comprises a support layer (thickness 150 um) and a microporous layer (thickness 30 um), wherein the support layer is carbon paper or carbon cloth, and the microporous layer comprises carbon powder and PTFE. The loading of the carbon powder in the microporous layer is 2 mg / cm 2 , and the content of PTFE in the microporous layer is 10%-30%. The cathode gas diffusion layer is prepared by the following method: Vulcan XC-72 carbon powder and PTFE emulsion are mixed, and a proper amount of ethanol is added. The slurry is prepared by ultrasonic stirring, and then coated on the surface of a commercial Torray carbon paper. The loading of the carbon powder and the content of PTFE are determined by weighing. Finally, the cathode gas diffusion layer is obtained by hot treatment at 340 DEG C for 30 min in a muffle furnace and then cooling to room temperature.
[0035] The anode gas diffusion electrode mainly comprises an anode gas diffusion layer and an anode catalyst layer. The anode gas diffusion layer is the same as the cathode gas diffusion layer, and the anode catalyst layer mainly comprises a catalyst and PTFE. The catalyst is Pt / C, the loading of the noble metal Pt is 0.1-0.3 mg / cm 2 , and the content of PTFE is 10%-30%. The anode catalyst layer is prepared by the following method: A certain amount of Pt / C catalyst is weighed, and then stirred and dispersed uniformly after being wetted with a small amount of deionized water. Then a certain amount of PTFE hydroalcoholic solution is added, and the catalyst slurry is obtained after ultrasonic dispersion. The anode catalyst layer is obtained by uniformly coating the surface of the microporous layer of the anode gas diffusion layer by ultrasonic spraying.
[0036] The thickness of the polybenzimidazole proton exchange membrane is 10-40 um, and the phosphoric acid doping amount is 200 wt%-400 wt%. The polybenzimidazole proton exchange membrane is prepared by the following method: The dried polybenzimidazole membrane is cut into a certain size, and the cut membrane is soaked in 85 wt% phosphoric acid at 120 DEG C for 60 min. The excess phosphoric acid on the surface of the membrane is absorbed with filter paper, and then weighed quickly to calculate the phosphoric acid doping amount of the membrane. The phosphoric acid doping amount of the membrane is investigated by the mass ratio of phosphoric acid to polybenzimidazole resin (mass of doped phosphoric acid / original mass of polybenzimidazole membrane). The acid immersion step is repeated until the phosphoric acid doping amount reaches 400 wt%.
[0037] Comparative Example The difference between this comparative example and Example 1 is that no serine polybenzimidazole solution was added to the catalyst slurry.
[0038] The catalyst slurries of Examples 1-3 and the comparative examples were uniformly sprayed onto the surface of the cathode gas diffusion layer using an ultrasonic spraying method. After drying, the cathode gas diffusion electrode was obtained. Each cathode gas diffusion electrode was then further fabricated into a high-temperature proton exchange membrane fuel cell.
[0039] According to GB / T 20042.5-2009, polarization curves were tested on each high-temperature proton exchange membrane fuel cell. The specific operating conditions were: single cell operating temperature of 160℃, anode feed of pure hydrogen, cathode feed of atmospheric pressure oxygen, and cathode / anode feed ratio of 1 / 1.
[0040] According to GB / T 20042.5-2009, cyclic voltammetry tests were conducted on various high-temperature proton exchange membrane fuel cells. The specific operating conditions were as follows: the single cell operating temperature was 160℃, the anode was fed with pure hydrogen, the cathode was fed with nitrogen at atmospheric pressure, and the cathode / anode feed ratio was 1 / 1.
[0041] See Figure 1 The polarization characteristic curves of the high-temperature proton exchange membrane fuel cells of Examples 1-3 and the comparative example of the present invention were obtained. As can be seen from the graphs, at 0.1 A / cm... 2 The membrane electrode voltages for Examples 1, 2, 3, and the comparative example of the present invention were measured to be 0.716V, 0.712V, 0.723V, and 0.710V, respectively. The fuel cell power densities for Examples 1, 2, 3, and the comparative example of the present invention were measured to be 71.6 mW / cm². -2 71.2mW cm -2 72.3mW cm -2 71.0mW cm -2 At 0.5A / cm 2 At that time, the membrane electrode voltages corresponding to Examples 1, 2, 3, and the comparative example of the present invention were measured to be 0.605V, 0.597V, 0.597V, and 0.579V, respectively. The fuel cell power densities corresponding to Examples 1, 2, 3, and the comparative example of the present invention were measured to be 302.5 mW / cm². -2 298.5 mW cm -2 298.5 mW cm -2 289.5mW cm -2 .
[0042] At low current densities, the membrane electrode polarization losses of the high-temperature proton exchange membrane fuel cells prepared in Examples 1-3 and the comparative example are comparable. At high current densities, the membrane electrode polarization losses of Examples 2-3 are smaller than those of the high-temperature proton exchange membrane fuel cells prepared in the comparative example, while the membrane electrode polarization loss of Example 1 is slightly larger than that of the comparative example. This indicates that when the proportion of SerPBI is larger, the power density of the fuel cell is greater and the performance is better.
[0043] See Figure 2 Cyclic voltammograms of the membrane electrodes of Examples 1-3 of this invention and the high-temperature proton exchange membrane fuel cell of the comparative example were obtained. Calculations showed that the electrochemical active area (ECSA) of Examples 1, 2, 3, and the comparative example was 89.9 m². 2 / g、69.6m 2 / g, 62.1m 2 / g, 57.8m 2 / g. Example 1 showed the highest ECSA content, indicating that the addition of SerPBI can regulate the phosphate distribution in the catalyst layer, thereby increasing the active surface area of the catalyst.
[0044] In summary, this invention provides a cathode catalyst slurry incorporating serine-polybenzimidazole and its preparation method. Serine-polybenzimidazole is obtained by condensing serine and polybenzimidazole, and then introduced into the cathode catalyst layer. Since the hydroxyl groups of SerPBI can crosslink with phosphoric acid under high-temperature conditions, the phosphoric acid is immobilized on SerPBI, thereby effectively reducing the adsorption of phosphoric acid at Pt active sites and minimizing phosphoric acid migration and loss, thus regulating the distribution of phosphoric acid in the cathode catalyst layer.
[0045] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.
Claims
1. A method for preparing a cathode catalyst slurry incorporating serine-polybenzimidazole, characterized in that, Includes the following steps: Step 1: Serine and polybenzimidazole are used as reactants to undergo a condensation reaction to obtain serine polybenzimidazole; Step 2: Mix the serine polybenzimidazole, binder and catalyst to obtain the cathode catalyst slurry incorporating serine polybenzimidazole.
2. The method for preparing the cathode catalyst slurry incorporating serine polybenzimidazole as described in claim 1, characterized in that, The specific steps of step 1 are as follows: Serine and polybenzimidazole were dissolved in dimethyl sulfoxide solution, and the solution was heated to 90℃-100℃ and reacted for 22h-24h to obtain the serine polybenzimidazole.
3. The method for preparing the cathode catalyst slurry incorporating serine polybenzimidazole as described in claim 1, characterized in that, In step 1, the mass ratio of serine to polybenzimidazole is 1:(1-5).
4. The method for preparing the cathode catalyst slurry incorporating serine polybenzimidazole as described in claim 1, characterized in that, In step 2, the binder is polytetrafluoroethylene, and the catalyst is a platinum-based catalyst or a platinum-based alloy catalyst.
5. The method for preparing the cathode catalyst slurry incorporating serine polybenzimidazole as described in claim 1, characterized in that, In step 2, the mass ratio of the serine polybenzimidazole to the binder is 1:(0.1-5).
6. The method for preparing the cathode catalyst slurry incorporating serine polybenzimidazole as described in claim 1, characterized in that, In step 2, the mass ratio of the serine polybenzimidazole to the catalyst is 1:(5-20).
7. The method for preparing the cathode catalyst slurry incorporating serine polybenzimidazole as described in claim 1, characterized in that, The specific steps of step 2 are as follows: Step 2.1: Disperse the adhesive in water and a surfactant solution to obtain an adhesive solution; Step 2.2: Disperse the catalyst in a solvent to obtain a catalyst solution; Step 2.3: Mix the serine polybenzimidazole, binder solution and catalyst solution to obtain the cathode catalyst slurry incorporating serine polybenzimidazole.
8. The method for preparing the cathode catalyst slurry incorporating serine polybenzimidazole as described in claim 7, characterized in that, The surfactant is FC-4430 or FC-003.
9. A cathode catalyst slurry incorporating serine-polybenzimidazole, characterized in that, It includes an ionomer, a binder, and a catalyst; the ionomer is serine polybenzimidazole, the binder is polytetrafluoroethylene, and the catalyst is a platinum-based catalyst or a platinum-based alloy catalyst.
10. A membrane electrode assembly for a proton exchange membrane fuel cell, characterized in that, It includes a proton exchange membrane, a cathode catalyst layer, and an anode catalyst layer, wherein the cathode catalyst layer and the anode catalyst layer are disposed on both sides of the proton exchange membrane, and the cathode catalyst layer is made of the cathode catalyst slurry as described in claim 9.