High-temperature fuel cell binder, preparation method and application
The preparation of polyether-type benzimidazole fiber filaments by electrospinning solved the problem of phosphoric acid blockage in high-temperature proton exchange membrane fuel cells, improved catalyst utilization and gas transport, and enhanced battery performance.
Patent Information
- Application Number
- CN202511048325.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-29
- Publication Date
- 2025-12-12
AI Technical Summary
In existing high-temperature proton exchange membrane fuel cells, the high phosphoric acid content of polybenzimidazole binder leads to the covering of catalyst active sites and pore blockage, affecting the cell output power.
Polyether-type benzimidazole short filaments were prepared by electrospinning technology and used in catalyst slurry to improve the compatibility between the membrane and the catalyst layer, and to absorb phosphoric acid in the catalyst layer, thereby reducing the occupation of active sites and pore blockage by phosphoric acid.
The improved catalyst utilization efficiency and gas transport channel construction enhanced the output power and performance of the fuel cell.
Smart Images
Figure CN121108930A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fuel cell technology, and in particular to a high-temperature fuel cell binder, its preparation method, and its application. Background Technology
[0002] A proton exchange membrane fuel cell (PEMFC) is a type of fuel cell that uses a proton exchange membrane as the electrolyte. Due to its high energy conversion efficiency and zero pollutant emissions, it is considered one of the future directions for green energy development. Compared to low-temperature proton exchange membrane fuel cells (LT-PEMFC), high-temperature proton exchange membrane fuel cells (HT-PEMFC) have an operating temperature range of 140-200℃ and offer advantages such as high CO poisoning tolerance, simplified hydrothermal management system, and enhanced fuel reactivity.
[0003] The membrane electrode assembly (MEA), the core component of the HT-PEMFC, consists of a proton exchange membrane, a catalyst layer, and a gas diffusion layer. The catalyst layer, the site of electrochemical reactions, is mainly composed of a catalyst, a binder, and pores between components. The binder in the catalyst layer not only conducts protons but also modulates its internal structure, promoting gas mass transfer; therefore, the binder plays a crucial role in the catalyst layer.
[0004] Currently, catalyst layers containing polybenzimidazole binders have a high phosphoric acid content. However, excessive free phosphoric acid can easily occupy catalyst active sites and clog catalyst layer pores, resulting in low catalyst utilization and hindered gas mass transfer, leading to a decrease in fuel cell output power.
[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention
[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a high-temperature fuel cell binder, preparation method and application, which aims to solve the problem that the high phosphoric acid content of the polybenzimidazole binder in the catalyst layer of high-temperature proton exchange membrane fuel cells leads to a decrease in battery output power due to the occupation of active sites and blockage of pores.
[0007] The technical solution of the present invention is as follows:
[0008] In a first aspect, the present invention provides a method for preparing a high-temperature fuel cell binder, comprising the following steps:
[0009] At room temperature, polyether-type benzimidazole is dissolved in an organic solvent to form a spinning solution;
[0010] The spinning solution is electrospinned to obtain fiber precursor, and the fiber precursor is cut into short fiber filaments;
[0011] The short fiber filaments are dispersed in a dispersion to obtain the high-temperature fuel cell binder.
[0012] Optionally, the mass percentage of polyether-type benzimidazole in the spinning solution is 8-15%.
[0013] Optionally, the organic solvent is N,N-dimethylacetamide or N-methylpyrrolidone.
[0014] It should be noted that centrifugation is required to remove impurities before forming the spinning solution. Centrifugation should be performed at 7000 rpm for 15 minutes.
[0015] Optionally, the dispersion is isopropanol or ethanol. Preferably, the dispersion is isopropanol.
[0016] Optionally, the voltage during electrospinning is 14-18kV, the flow rate is 0.1-0.5mL / h, the receiving distance is 10-20cm, and the temperature is 30-50℃.
[0017] Optionally, the fiber filament is cut into short filaments by first subjecting it to ultrasound and then homogenizing it. The ultrasound frequency is 30-40kHz and the homogenization speed is 1000-2000rpm.
[0018] Optionally, the mass fraction of short fiber filaments in the high-temperature fuel cell binder is 2-3%.
[0019] In a second aspect, the present invention provides a high-temperature fuel cell binder prepared by the aforementioned preparation method.
[0020] In a third aspect, the present invention provides an application of a high-temperature fuel cell binder, wherein the high-temperature fuel cell binder is applied in a catalyst slurry and together with the catalyst slurry forms a catalytic layer of a membrane electrode.
[0021] Optionally, the short fiber filaments in the high-temperature fuel cell binder account for 2-3.5% of the weight of the catalyst slurry.
[0022] Beneficial effects: This invention provides a high-temperature fuel cell binder, its preparation method, and its application. The polyether-type benzimidazole fiber prepared by this invention has the following advantages: First, since the polyether-type benzimidazole has the same composition as the high-temperature membrane, it can improve the compatibility between the membrane and the catalyst layer. Second, the short fiber can absorb phosphoric acid in the catalyst layer, reducing the occupation of active sites and pore blockage by phosphoric acid, thereby improving the utilization of the catalyst and the construction of gas transport channels. Attached Figure Description
[0023] Figure 1 This is a flowchart illustrating the process of preparing the high-temperature fuel cell binder according to the present invention.
[0024] Figure 2The following are SEM comparison images of fibers in Example 3 of the present invention: (a) is an SEM image of polyether-type benzimidazole fiber precursor, and (b) is an SEM image of fiber staple.
[0025] Figure 3 This is a diameter distribution diagram of the short fiber filaments obtained in Example 3 of the present invention.
[0026] Figure 4 The image shows the cell polarization curves of the membrane electrode obtained in various embodiments of the present invention.
[0027] Figure 5 The images show the in-situ electrochemical impedance spectroscopy of the membrane electrodes obtained in various embodiments of the present invention. Detailed Implementation
[0028] This invention provides a high-temperature fuel cell binder, its preparation method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0029] Proton exchange membrane fuel cells (PEMFCs) have become one of the most promising types of fuel cells due to their high energy density, high power density, and fast start-up. Based on temperature, PEMFCs can be divided into low-temperature proton exchange membrane fuel cells (LT-PEMFCs) and high-temperature proton exchange membrane fuel cells (HT-PEMFCs). Compared to LT-PEMFCs, HT-PEMFCs have an operating temperature range of 140-200℃ and offer advantages such as higher CO poisoning tolerance, a simplified hydrothermal management system, and enhanced fuel reactivity.
[0030] As a core component of HT-PEMFC, the membrane electrode assembly consists of a proton exchange membrane, a catalyst layer, and a gas diffusion layer. The catalyst layer, serving as the site of electrochemical reactions, includes the catalyst, binder, and pores between components. The binder not only facilitates proton transport within the catalyst layer but also modulates its structure, promoting gas mass transfer. Therefore, the binder has a significant impact on the catalyst layer.
[0031] Significant progress has been made in binders for LT-PEMFCs. For example, commercially available perfluorosulfonic acid (PFSA) ionomers exhibit good proton conductivity at low temperatures and are therefore widely used as catalyst layer binders. However, under high-temperature dehydration conditions, the PFSA ion channels, which rely on liquid water for proton conduction, collapse, leading to a sharp drop in proton conductivity. Under high-temperature anhydrous conditions, the imidazole groups on polybenzimidazole (PBI) can adsorb phosphoric acid to form acid-base pairs. Protons migrate via hopping conduction through the phosphoric acid network without the need for liquid water; therefore, PBI is commonly used as a binder in HT-PEMFCs. However, the acid-loving nature of PBI results in a higher concentration of free phosphoric acid in the catalyst layer, which can easily cover the catalyst and clog pores, leading to low catalyst utilization and poor gas mass transfer, thus limiting the fuel cell's output power. Therefore, modifying the PBI structure is essential.
[0032] Based on this, this embodiment provides a method for preparing a high-temperature fuel cell binder, such as... Figure 1 As shown, it includes the following steps:
[0033] S1. At room temperature, polyether-type benzimidazole is dissolved in an organic solvent to form a spinning solution;
[0034] S2. The spinning solution is electrospinned to obtain fiber filaments, and the fiber filaments are cut into short fiber filaments;
[0035] S3. Disperse the short fiber filaments in a dispersion liquid to obtain the high-temperature fuel cell binder.
[0036] In this embodiment, a spinning solution is formed by dissolving polyether-type benzimidazole, and then the fiber precursor is obtained by electrospinning. The fiber precursor is then cut into short polyether-type benzimidazole fibers and dispersed in a dispersion solution to prepare a high-temperature fuel cell binder. The short fibers obtained in this embodiment are nanofibers with a length between 300-400 nm and a diameter between 10-30 nm.
[0037] Since polyether-type benzimidazole has the same composition as the high-temperature membrane of HT-PEMFC, using this binder as a catalyst can improve the compatibility between the membrane and the catalyst layer. On the other hand, the fiber can absorb phosphoric acid in the catalyst layer, reducing the occupation of active sites and pore blockage by phosphoric acid, thereby improving the utilization efficiency of the catalyst and the construction of gas transport channels.
[0038] The polyether-type benzimidazole in this embodiment has the property of absorbing phosphoric acid. The short fibers prepared still retain the property of absorbing phosphoric acid. In addition, since the specific surface area of the short fibers is also higher, the ability to absorb phosphoric acid is even higher.
[0039] In some embodiments, the mass percentage of polyether-type benzimidazole in the spinning solution is 8-15%, for example, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%.
[0040] In some embodiments, the organic solvent is N,N-dimethylacetamide or N-methylpyrrolidone.
[0041] It should be noted that centrifugation is required to remove impurities before forming the spinning solution. Centrifugation should be performed at 7000 rpm for 15 minutes.
[0042] In some embodiments, the dispersion is isopropanol or ethanol. Preferably, the dispersion is isopropanol.
[0043] In some embodiments, the voltage during electrospinning is 14-18 kV, preferably 17.3 kV; the flow rate is 0.1-0.5 mL / h, preferably 0.1 mL / h; the receiving distance is 10-20 cm, preferably 20 cm; and the temperature is 30-50 °C, preferably 50 °C.
[0044] In some embodiments, the fiber filament is first cut into short filaments by ultrasonication followed by homogenization. The ultrasonic frequency is 30-40kHz, preferably 40kHz, and the homogenization speed is 1000-2000rpm, preferably 2000rpm.
[0045] Optionally, the mass fraction of short fiber filaments in the high-temperature fuel cell binder is 2-3%, preferably 2.5%.
[0046] This embodiment also provides a high-temperature fuel cell binder, which is prepared by the aforementioned preparation method.
[0047] This embodiment also provides an application of a high-temperature fuel cell binder, which is applied to a catalyst slurry and together with the catalyst slurry forms the catalytic layer of the membrane electrode.
[0048] In some embodiments, the short fiber filaments in the high-temperature fuel cell binder account for 2-3.5% of the weight of the catalyst slurry.
[0049] The present invention will be further described below with reference to specific embodiments.
[0050] Example 1
[0051] 1. Preparation of polyether-type benzimidazole short fibers:
[0052] 0.5 g of commercial polyether benzimidazole (OPBI) was added to a sample vial containing 4.5 g of N,N-dimethylacetamide. A magnetic stir bar was added, and the mixture was stirred at room temperature until the OPBI was completely dissolved, preparing a 10% OPBI mixed solution. Impurities were then removed by centrifugation at 7000 rpm for 15 minutes to obtain the spinning solution. Fiber precursors were obtained from the spinning solution under the conditions of 17.3 kV, a flow rate of 0.1 mL / h, a receiving distance of 20 cm, and a temperature of 50 °C. OPBI short filaments were then obtained by ultrasonication at 40 kHz and homogenization at 1000 rpm.
[0053] 2. Preparation of high-temperature fuel cell binder:
[0054] 0.1 mg of OPBI short fibers were added to a 10 mL transparent bottle containing 3.9 mg of isopropanol, and the mixture was sonicated at room temperature until the OPBI short fibers were evenly dispersed, thus preparing an OPBI short fiber solution with a mass fraction of 2.5%.
[0055] 3. Membrane electrode:
[0056] Add 5.6 mg of OPBI short filament solution (where the weight of OPBI short filament is 2% of the platinum-carbon catalyst) to a slurry containing 7 mg of platinum-carbon catalyst, and sonicate for 40 minutes to disperse the OPBI short filament solution evenly in the catalyst slurry. The catalyst slurry obtained in this example is named 2% OPBI / spinning.
[0057] Example 2
[0058] The difference between this embodiment and Embodiment 1 is that 7 mg of OPBI short filament solution (where the weight of OPBI short filament is 2.5% of the weight of the platinum-carbon catalyst) was added to the slurry containing 7 mg of platinum-carbon catalyst, and the OPBI short filament solution was sonicated for 40 minutes to disperse the OPBI short filament solution evenly in the catalyst slurry. The catalyst slurry obtained in this embodiment is named 2.5% OPBI / spinning.
[0059] Example 3
[0060] The difference between this embodiment and Example 1 is that 8.4 mg of OPBI short filament solution (where the weight of OPBI short filament is 3% of the platinum-carbon catalyst) was added to a slurry containing 7 mg of platinum-carbon catalyst, and the OPBI short filament solution was sonicated for 40 minutes to disperse the OPBI short filament solution evenly in the catalyst slurry. The catalyst slurry obtained in this embodiment is named 3% OPBI / spinning. Figure 2 The following are SEM comparison images of fibers in Example 3 of the present invention: (a) is an SEM image of polyether-type benzimidazole fiber precursor, and (b) is an SEM image of fiber staple. Figure 3 This is a diameter distribution diagram of the short fiber filaments obtained in Example 3 of the present invention. From... Figure 3It can be seen that the diameter of the short fiber obtained in this embodiment is between 10-30 nm.
[0061] Example 4
[0062] The difference between this embodiment and Example 1 is that 9.8 mg of OPBI short filament solution (where the weight of OPBI short filament is 3.5% of the platinum-carbon catalyst) was added to a slurry containing 7 mg of platinum-carbon catalyst, and the mixture was sonicated for 40 minutes to ensure that the OPBI short filament solution was evenly dispersed in the catalyst slurry. The catalyst slurry obtained in this embodiment is named 3.5% OPBI / spinning.
[0063] The catalyst slurry formulations for the above embodiments are shown in Table 1. Then, catalyst slurries with different binder contents are sprayed onto the gas diffusion layer (carbon paper) to form a catalyst layer, with an effective catalytic area of 5 cm² for each layer. 2 Then, the relevant performance was characterized.
[0064] Table 1 Catalyst slurry formulation for Examples 1-4
[0065]
[0066] The effect of binder content on MEAs cell performance:
[0067] To investigate the effect of different binder contents on proton exchange membrane fuel cells, the membrane electrodes of Example 1 (containing 2% binder), Example 2 (containing 2.5% binder), Example 3 (containing 3% binder), and Example 4 (containing 3.5% binder) were placed in hydrogen-oxygen fuel cells and their respective cell performance was measured under anhydrous conditions at 160°C.
[0068] from Figure 4 As can be seen, the binder content has a significant impact on battery performance. With increasing binder content, the power density first increases and then decreases, with the membrane electrode containing 3% binder exhibiting the highest power density, reaching 678 mW / cm². -2 Therefore, a suitable binder can help improve the proton conduction of the catalyst layer while fixing the phosphoric acid in the catalyst layer, reducing the coverage of active sites and pore blockage by phosphoric acid.
[0069] Electrochemical impedance:
[0070] from Figure 5 As can be seen, the ohmic resistance of the membrane electrode first decreases and then increases with the increase of the binder content. In Example 3, the membrane electrode with a binder content of 3% OPBI short filaments has the lowest ohmic resistance of 1.4 ohms cm⁻¹. 2 This indicates a good interfacial contact between the catalyst layer and the film; its charge transfer resistance is relatively small, at 2.0 ohm cm⁻¹. 2This indicates that the addition of short fiber filaments can absorb phosphoric acid, thereby improving gas mass transfer in the catalyst layer, resulting in the highest battery performance. Therefore, the addition of a binder increases the interfacial contact between the catalyst layer and the membrane.
[0071] In summary, the polyether-type benzimidazole short filaments provided by this invention have the following advantages: firstly, since the polyether-type benzimidazole has the same composition as the high-temperature membrane, it can improve the compatibility between the membrane and the catalyst layer; secondly, the short fibers can absorb phosphoric acid in the catalyst layer, reducing the occupation of active sites and pore blockage by phosphoric acid, thereby improving the utilization of the catalyst and the construction of gas transport channels.
[0072] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.
Claims
1. A method of making a high temperature fuel cell binder, characterized by: The method comprises the following steps: dissolving the polyether benzimidazole in an organic solvent to form a spinning solution at room temperature; spinning the spinning solution to obtain fiber filaments; cutting the fiber filaments into fiber short filaments; 2. The method for preparing a high-temperature fuel cell binder according to claim 1, characterized in that: dispersing the fiber short filaments in a dispersion liquid to obtain the high-temperature fuel cell binder.
3. The method for preparing a high-temperature fuel cell binder according to claim 1, characterized in that: The organic solvent is N,N-dimethylacetamide or N-methyl pyrrolidone.
4. The method of claim 1, wherein the high temperature fuel cell binder is prepared by: The mass percentage of the polyether benzimidazole in the spinning solution is 8%-15%.
5. The method for preparing a high-temperature fuel cell binder according to claim 1, characterized in that: The dispersion liquid is isopropyl alcohol or ethanol.
6. The method of claim 1, wherein the high temperature fuel cell binder is prepared by: The voltage during electrospinning is 14-18 kV, the flow rate is 0.1-0.5 mL / h, the receiving distance is 10-20 cm, and the temperature is 30-50 °C.
7. The method for preparing a high-temperature fuel cell binder according to claim 1, characterized in that: The fiber filaments are cut into fiber short filaments by ultrasonic treatment and then by homogenization, the ultrasonic frequency is 30-40 kHz, and the homogenization speed is 1000-2000 rpm.
8. A high temperature fuel cell binder characterized by: The mass percentage of the fiber short filaments in the high-temperature fuel cell binder is 2-3%.
9. Use of a high temperature fuel cell binder, characterized in that: Prepared by the preparation method of any one of claims 1-7.
10. Use of a high temperature fuel cell binder according to claim 9, characterized in that: The high-temperature fuel cell binder of claim 8 is applied to a catalyst slurry, and together with the catalyst slurry, forms a catalytic layer of a membrane electrode. The fiber short filaments in the high-temperature fuel cell binder account for 2-3.5% of the weight of the catalyst slurry.