Proton exchange membrane with ordered ion transport channels and preparation method thereof

Abstract

The present invention provides a proton exchange membrane with ordered ion transport channels and a method for preparing the same. The present invention utilizes electrospinning to simultaneously co-spin coaxial multilayer fibers and reinforcing fibers to produce a composite fiber porous membrane. A pore-blocking agent comprising a perfluorosulfonic acid resin and fibers is then used to fill the interstices within the composite fiber porous membrane. The membrane is then subjected to heat pressing, flattening, and other processes to produce a proton exchange membrane with ordered ion transport channels. The resulting proton exchange membrane exhibits excellent mechanical strength, good electrical conductivity, and stability at both high and low temperatures.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a proton exchange membrane with ordered ion transmission channels and a preparation method thereof. Background Art

[0002] The proton exchange membrane fuel cell (PEMFC) is one of the most promising energy sources for electric vehicles. It consists of end plates, insulating plates, current collectors, bipolar plates, and a membrane electrode. The membrane electrode, the core of the fuel cell stack, is where the electrochemical reaction occurs. Inside the membrane electrode, hydrogen molecules on the anode side lose electrons under the action of a catalyst, becoming protons. These protons then pass through the selective proton exchange membrane to the cathode side, where they gain electrons under the action of the cathode catalyst and combine with oxygen molecules to form water molecules.

[0003] Proton exchange membranes must exhibit good proton conductivity under both low and high temperature conditions. At low temperatures, the membrane requires a certain humidity, while at high temperatures, it requires a certain amount of acid doping to maintain high proton conductivity. However, the acid within the membrane is continuously lost during use, poisoning the catalyst. Excessive doping can also degrade the membrane's mechanical properties. Therefore, there is an urgent need for a proton exchange membrane with excellent proton conductivity and stable performance. Summary of the Invention

[0004] To address the challenges of the prior art, the present invention provides a proton exchange membrane with ordered ion transport channels and a method for preparing the membrane. This method reduces acid loss in the membrane, improves mechanical strength, and maintains good proton conductivity despite repeated cycles of high-temperature, low-humidity, and low-temperature, high-humidity conditions.

[0005] The present invention provides a method for preparing a proton exchange membrane with ordered ion transport channels, which mainly comprises the following steps:

[0006] S1: Electrospinning a coaxial multilayer fiber through a coaxial spinning tube on one side of a spinning receiving roller, and electrospinning a reinforcing fiber through a single-layer spinning tube. The coaxial multilayer fiber and the reinforcing fiber are interwoven on the spinning receiving roller and dried to form a composite fiber porous membrane.

[0007] S2: Filling the voids of the composite fiber porous membrane with a pore-blocking agent, wherein the pore-blocking agent comprises a perfluorosulfonic acid resin solution, reinforcing fibers, and a quenching agent;

[0008] S3: hot pressing and flattening treatment to obtain a proton exchange membrane with ordered ion transport channels.

[0009] The coaxial multilayer fiber referred to in step S1 comprises a shell layer and at least one coaxial inner layer. To prepare the coaxial multilayer fiber, the coaxial spinning tube used in step S1 comprises a shell channel and at least one coaxially arranged inner channel. The shell channel is supplied with a sulfonated polymer or phosphorylated polymer solution as the shell spinning solution, while the at least one inner channel is supplied with an acid solution or a perfluorosulfonic acid resin solution as the inner spinning solution. Preferably, the coaxial spinning tube may have two inner channels, one for supplying the acid solution and the other for supplying the perfluorosulfonic acid resin solution.

[0010] The single-layer spinning tube is supplied with a perfluorosulfonic acid resin solution as a single-layer spinning solution.

[0011] In step S2, the pore-blocking agent can be filled into the voids of the composite fiber porous membrane by casting, extrusion, screen printing, spin coating, spraying or dipping. In step S3, the hot pressing treatment is performed by roller or flat plate compression.

[0012] Specifically, the aforementioned sulfonated polymer used as the shell spinning solution includes at least one of sulfonated naphthalene polybenzimidazole, sulfonated polyetheretherketone, sulfonated polyaryletherketone, sulfonated polyphenylene ether, sulfonated polyethersulfone, and sulfonated polyimide; the phosphorylated polymer includes at least one of phosphorylated benzimidazole and phosphorylated polyetheretherketone.

[0013] Specifically, the acid solution used as the inner layer spinning solution includes at least one of phosphoric acid, polyphosphoric acid, polyvinyl phosphoric acid, and methanesulfonic acid.

[0014] Specifically, the pore plugging agent used in step S2 comprises a perfluorosulfonic acid resin solution, a reinforcing fiber, and a quencher; wherein the reinforcing fiber comprises at least one of a hydrophobic reinforcing fiber and a hydrophilic reinforcing fiber; the hydrophobic reinforcing fiber may be, for example, silica, alumina, calcium oxide, boron oxide, magnesium oxide, or silicon carbide, while the hydrophilic reinforcing fiber may be, for example, sulfonated polyetheretherketone, sulfonated polyaryletherketone, sulfonated polyphenylene oxide, sulfonated polyethersulfone, or sulfonated polyimide; if both hydrophobic and hydrophilic reinforcing fibers are used, the specific ratio of the two depends on the durability test and conductivity capability of the membrane. The quencher comprises at least one of cerium oxide and manganese oxide.

[0015] Specifically, after the hot pressing and flattening treatments in step S3, further treatments such as protonation and water washing are performed.

[0016] Through the above-mentioned preparation method, the present invention provides a proton exchange membrane with an ordered ion transport channel, wherein the proton exchange membrane has an intermediate layer and a surface layer, wherein the intermediate layer is composed of a composite fiber porous membrane interwoven with coaxial multilayer fibers and reinforcing fibers; and the surface layer contains perfluorosulfonic acid resin and reinforcing fibers.

[0017] The technical effects achieved by the present invention are as follows:

[0018] 1. The core-shell structure formed by coaxial electrospinning is ordered rather than chaotic, which can increase the proton conductivity and mechanical strength of the proton exchange membrane and improve the compatibility of materials during the preparation process of the proton exchange membrane;

[0019] 2. The mechanical strength of the proton exchange membrane is increased by intertwining reinforcing fibers made of perfluorosulfonic acid resin and coaxial multi-layer fibers into an interpenetrating mesh structure;

[0020] 3. A pore-blocking agent containing a perfluorosulfonic acid resin solution and reinforced fibers is used to fill and form a surface layer on the composite fiber porous membrane. This ensures that the ordered proton exchange membrane has good proton conductivity at low temperatures while also improving mechanical strength.

[0021] 4. By using a sulfonated or phosphated polymer as the shell layer of the coaxial multilayer fiber, the high-temperature performance of the proton exchange membrane is guaranteed. More importantly, the charge balance between the shell and inner layers ensures that the acidic groups are protected at the center. This not only enhances the proton conductivity of the ordered proton exchange membrane at high temperatures, but also effectively prevents acid loss and improves the stability of the proton exchange membrane. As a result, the proton exchange membrane of the present invention maintains excellent proton conductivity even when repeatedly subjected to high-temperature, low-humidity, and low-temperature, high-humidity conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0023] Figure 1 The flowchart of the preparation of the proton exchange membrane in Example 1 is shown;

[0024] Figure 2 A schematic diagram of the ion channel of the coaxial multilayer fiber in Example 1 is shown;

[0025] Figure 3 The flowchart of the preparation of the proton exchange membrane in Example 3 is shown;

[0026] Figure 4 A schematic diagram of the ion channel of the coaxial multi-layer fiber in Example 3 is shown.

[0027] Explanation of the accompanying figures: 1-coaxial spinning tube; 2-single-layer spinning tube; 3-spinning receiving roller; 4-composite fiber porous membrane; 5-middle layer; 6-surface layer. DETAILED DESCRIPTION

[0028] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these illustrative embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0029] As used herein, the term "include" and its variations denote open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" denotes "and / or". The term "based on" denotes "based at least in part on". The terms "connected" and "connected" denote connection or communication directly or indirectly through other components. The terms "first", "second", etc. may refer to different or the same objects, but do not directly indicate a difference in order or importance. Other explicit and implicit definitions may also be included below.

[0030] The present invention provides a method for preparing a proton exchange membrane with ordered ion transport channels, which mainly comprises the following steps:

[0031] S1: Electrospinning a coaxial multilayer fiber through a coaxial spinning tube on one side of a spinning receiving roller, and electrospinning a reinforcing fiber through a single-layer spinning tube. The coaxial multilayer fiber and the reinforcing fiber are interwoven on the spinning receiving roller and dried to form a composite fiber porous membrane.

[0032] S2: Filling the voids of the composite fiber porous membrane with a pore-blocking agent, wherein the pore-blocking agent comprises a perfluorosulfonic acid resin solution, reinforcing fibers, and a quenching agent;

[0033] S3: hot pressing and flattening treatment to obtain a proton exchange membrane with ordered ion transport channels.

[0034] In step S1, the coaxial spinning tube and the single-layer spinning tube are fixed on the same side of the spinning receiving roller, and the coaxial spinning tube and the single-layer spinning tube are both connected to the positive pole of the high-voltage power supply, and the spinning receiving roller is connected to the negative pole of the high-voltage power supply. The spinning receiving roller has been pre-covered with a substrate, which can specifically be aluminum foil, polytetrafluoroethylene film, polyethylene terephthalate film, polyethylene naphthalate film and other materials. The present invention does not impose any special restrictions on the specific parameters of electrospinning. As an example, the spinning solution flow rate is 0.001mL / min, the receiving distance is 15cm, the spinning receiving roller speed is 2000r / min, and the voltage is 26kV.

[0035] The coaxial spinning tube comprises a shell channel and at least one coaxially arranged inner channel. The shell channel is supplied with a sulfonated polymer or phosphorylated polymer solution as the shell spinning solution, while the at least one inner channel is supplied with an acid solution or a perfluorosulfonic acid resin solution as the inner spinning solution. Preferably, the coaxial spinning tube may have two inner channels, one for supplying the acid solution and the other for supplying the perfluorosulfonic acid resin solution. This is illustrated below with reference to specific embodiments:

[0036] Example 1

[0037] like Figure 1 As shown, the coaxial spinning tube 1 has a shell channel and a coaxially arranged inner channel. The shell channel is supplied with a sulfonated naphthalene polybenzimidazole solution as the shell spinning solution, while the inner channel is supplied with a phosphoric acid solution as the inner spinning solution. The single-layer spinning solution in the single-layer spinning tube 2 is composed of a perfluorosulfonic acid resin solution. By placing the coaxial spinning tube 1 and the single-layer spinning tube 2 on the same side of the spinning receiving roller 3 for synchronous co-spinning, the coaxial multi-layer fibers prepared by the coaxial spinning tube 1 and the reinforcing fibers prepared by the single-layer spinning tube 2 are interwoven into a mesh structure. After drying to remove the solvent, a composite fiber porous membrane is obtained.

[0038] The ion channels of the coaxial multilayer fibers obtained by the above method are as follows Figure 2 As shown in the figure, the charge balance between the shell and inner layer keeps the acidic group in the protected center, effectively preventing the loss of acid.

[0039] After the composite fiber porous membrane is formed, a pore-blocking agent is cast to fill the pores within the composite fiber porous membrane. The pore-blocking agent comprises a perfluorosulfonic acid resin solution, reinforcing fibers, and a quenching agent. Specifically, hydrophobic silica and hydrophilic sulfonated polyaryletherketone are used as the reinforcing fibers, and cerium oxide is used as the quenching agent.

[0040] Finally, the membrane was hot-pressed at 145°C for 25 minutes to produce a proton exchange membrane with ordered ion transport channels. The resulting proton exchange membrane comprises an intermediate layer 5 and a surface layer 6. The intermediate layer 5 is composed of a porous composite fiber membrane interwoven with coaxial multilayer fibers and reinforcing fibers. The surface layer 6 is primarily composed of perfluorosulfonic acid resin and reinforcing fibers.

[0041] Example 2

[0042] This embodiment is similar to Example 1. The coaxial spinning tube comprises a shell channel and a coaxially arranged inner channel. A phosphorylated benzimidazole solution is used as the shell spinning solution in the shell channel, while a perfluorosulfonic acid resin solution is used as the inner layer spinning solution in the inner channel. The single-layer spinning solution in the single-layer spinning tube consists of a perfluorosulfonic acid resin solution.

[0043] After the composite fiber porous membrane is obtained, a pore-blocking agent is screen-printed to fill the pores of the composite fiber porous membrane. The pore-blocking agent comprises a perfluorosulfonic acid resin solution, a reinforcing fiber, and a quenching agent. Specifically, sulfonated polyetheretherketone is used as the reinforcing fiber, and manganese oxide is used as the quenching agent.

[0044] Finally, the membrane was hot-pressed at 140°C for 30 min to obtain a proton exchange membrane with ordered ion transport channels.

[0045] Example 3

[0046] like Figure 3 As shown, the coaxial spinning tube 1 has a shell channel and two coaxially arranged inner channels. The shell channel is supplied with a sulfonated naphthalene polybenzimidazole solution as the shell spinning solution, and the two inner channels from the outside to the inside are respectively supplied with a phosphoric acid solution and a perfluorosulfonic acid resin solution as the inner spinning solution. The single-layer spinning solution in the single-layer spinning tube 2 is composed of a perfluorosulfonic acid resin solution. By placing the coaxial spinning tube 1 and the single-layer spinning tube 2 on the same side of the spinning receiving roller 3 for synchronous co-spinning, the coaxial multi-layer fibers prepared by the coaxial spinning tube 1 and the reinforcing fibers prepared by the single-layer spinning tube 2 are interwoven into a mesh structure. After drying and removing the solvent, a composite fiber porous membrane is obtained.

[0047] The ion channels of the coaxial multilayer fibers obtained by the above method are as follows Figure 4 As shown in the figure, the charges of the shell sulfonated polymer, the middle acid layer, and the core perfluorosulfonic acid resin are balanced, so that the acid group is at the center of protection, effectively preventing the loss of acid.

[0048] After the composite fiber porous membrane is obtained, a pore-blocking agent is impregnated to fill the pores of the composite fiber porous membrane. The pore-blocking agent comprises a perfluorosulfonic acid resin solution, reinforcing fibers, and a quenching agent. Specifically, hydrophobic aluminum oxide is used as the reinforcing fibers, and cerium oxide is used as the quenching agent.

[0049] Finally, the membrane was hot-pressed at 145°C for 25 min to obtain a proton exchange membrane with ordered ion transport channels.

[0050] While various embodiments of the present disclosure have been described above, those skilled in the art will appreciate that the foregoing description is merely illustrative and non-exhaustive, and is not intended to limit the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or improvements over the prior art, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing a proton exchange membrane with ordered ion transport channels, characterized in that: The method comprises the following steps: S1: Electrospinning a coaxial multilayer fiber through a coaxial spinning tube on one side of a spinning receiving roller, and electrospinning a reinforcing fiber through a single-layer spinning tube. The coaxial multilayer fiber and the reinforcing fiber are interwoven on the spinning receiving roller and dried to form a composite fiber porous membrane. The coaxial spinning tube comprises a shell channel and at least one coaxially arranged inner channel, the shell channel is supplied with a sulfonated polymer or a phosphorylated polymer solution as the shell spinning solution, and the at least one inner channel is supplied with an acid solution or a perfluorosulfonic acid resin solution as the inner spinning solution; the single-layer spinning tube is supplied with a perfluorosulfonic acid resin solution as the single-layer spinning solution; S2: Filling the voids of the composite fiber porous membrane with a pore-blocking agent, wherein the pore-blocking agent comprises a perfluorosulfonic acid resin solution, reinforcing fibers, and a quenching agent; S3: hot pressing and flattening treatment to obtain a proton exchange membrane with ordered ion transport channels.

2. The method for preparing a proton exchange membrane with ordered ion transport channels according to claim 1, characterized in that: In step S2, the pore-blocking agent is used to fill the voids of the composite fiber porous membrane by casting, extrusion, screen printing, spin coating, spraying or dipping.

3. The method for preparing a proton exchange membrane with ordered ion transport channels according to claim 1, characterized in that: The sulfonated polymer includes at least one of sulfonated naphthalene polybenzimidazole, sulfonated polyetheretherketone, sulfonated polyaryletherketone, sulfonated polyphenylene oxide, sulfonated polyethersulfone, and sulfonated polyimide.

4. The method for preparing a proton exchange membrane with ordered ion transport channels according to claim 1, characterized in that: The phosphorylated polymer includes at least one of phosphorylated benzimidazole and phosphorylated polyetheretherketone.

5. The method for preparing a proton exchange membrane with ordered ion transport channels according to claim 1, characterized in that: The acid solution includes at least one of phosphoric acid, polyphosphoric acid, polyvinyl phosphoric acid, and methanesulfonic acid.

6. The method for preparing a proton exchange membrane with ordered ion transport channels according to claim 1, characterized in that: The reinforcing fibers include at least one of hydrophobic reinforcing fibers and hydrophilic reinforcing fibers.

7. The method for preparing a proton exchange membrane with ordered ion transport channels according to claim 6, characterized in that: The hydrophobic reinforcing fiber comprises silicon dioxide, aluminum oxide, calcium oxide, boron oxide, magnesium oxide or silicon carbide, and the hydrophilic reinforcing fiber comprises sulfonated polyetheretherketone, sulfonated polyaryletherketone, sulfonated polyphenylene oxide, sulfonated polyethersulfone or sulfonated polyimide.

8. The method for preparing a proton exchange membrane with ordered ion transport channels according to claim 1, characterized in that: The quencher includes at least one of cerium oxide and manganese oxide.

9. A proton exchange membrane with ordered ion transport channels, characterized in that: The proton exchange membrane is prepared by the method for preparing a proton exchange membrane with an ordered ion transport channel according to any one of claims 1 to 8, and the proton exchange membrane has an intermediate layer and a surface layer; The middle layer is composed of a composite fiber porous membrane formed by interweaving coaxial multi-layer fibers and reinforcing fibers; the surface layer contains perfluorosulfonic acid resin and reinforcing fibers.

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