A membrane electrode catalyst layer inkjet printing ink and its preparation method and application

Abstract

The present invention discloses a membrane electrode catalyst layer inkjet printing ink and a preparation method and application thereof, belonging to the field of fuel cells and water electrolysis. The inkjet printing ink is composed of a catalyst, a solvent, an adhesive and a resin solution, and the mass ratio of the resin in the catalyst, the solvent, the adhesive and the resin solution is 1:30-70:5-50:0.1-4; the solvent is one or more of isopropanol, n-propanol, ethanol or water; the adhesive is one or more of ethylene glycol, propylene glycol, polyethylene glycol and glycerol. Compared with the prior art, the present invention prepares a highly stable fuel cell and a membrane electrode inkjet printing ink for water electrolysis without adding any components that affect the electrode performance. There is no sedimentation phenomenon when standing for a long time at room temperature, and it can be printed continuously in the ink cartridge without problems such as nozzle clogging and unsmooth printing. The membrane electrode prepared by inkjet of the ink of the present invention shows good battery performance after drying, which is better than traditional ink.

Description

Technical Field

[0001] The invention belongs to the field of fuel cells and water electrolysis, and in particular relates to a membrane electrode catalyst layer inkjet printing ink and a preparation method and application thereof. Background Art

[0002] Membrane electrode (MEA) is the core component of fuel cells and water electrolyzers, and the preparation process of MEA largely determines the performance of fuel cells and water electrolysis. There are many conventional methods for preparing MEA, such as traditional spraying, roll-to-roll process, coating method, etc., but conventional methods have some shortcomings, such as complicated procedures, low preparation efficiency, uneven prepared catalytic layer, low catalyst utilization, catalyst loading and carbon black micromorphology are difficult to control, etc., resulting in high cost of membrane electrode and unstable performance.

[0003] As one of the more popular preparation technologies, inkjet printing technology has many advantages, such as wide application range, simple operation, low cost, rapid batch preparation, and controllable morphology. At present, the application scope of inkjet printing technology has been greatly expanded from its traditional fields and has a wider range of uses. The printing materials are also becoming more abundant, such as printing metals, oxide films, carbon nanotubes, ceramics, semiconductor materials, gas sensing films, transistors, polymer molecular films, small organic particles, proteins, cell organs, neurons, bacteria, etc. There is also great potential for development in printing membrane electrode catalyst inks. Introducing inkjet printing technology into the field of membrane electrode preparation has many advantages: first, inkjet printing technology can well control the content of precious metal catalysts in the catalytic layer and the thickness of the catalytic layer, which is convenient for the preparation of low platinum, ultra-low platinum loading and ultra-thin catalytic layers, and compared with other preparation technologies, the catalytic layer has a higher flatness; second, inkjet printing technology can realize the simultaneous high-precision printing of multiple materials. Through this technology, functional structures such as gas channels and drainage channels in the catalytic layer can be established, thereby improving gas mass transfer, slowing down the occurrence of flooding, reducing the amount of precious metal catalysts, and preparing functionally ordered electrodes; third, inkjet printing technology has a very broad application prospect in the large-scale mass production of membrane electrodes, which can realize the rapid and large-scale continuous preparation of membrane electrodes, and simultaneously complete the membrane electrode sealing steps, simplify the process flow, and improve production efficiency.

[0004] The inkjet printing process itself is very convenient and fast, but it is challenging to successfully achieve inkjet printing. The challenge lies in obtaining ink with high dispersibility and high stability. If the dispersibility is not good, it is easy to clog the nozzle; if the stability is not good, sedimentation will occur during the spraying process, resulting in lower and lower concentrations of the printed catalyst. In addition, inkjet printing technology is used in fuel cells. It is necessary to ensure that the conductivity and adhesion stability of the ink forming the catalytic layer meet the requirements in order to obtain a membrane electrode with excellent electrochemical performance. At present, the common inkjet printing ink for fuel cells is composed of catalyst particles, dispersants and resin solutions. The obtained ink is a suspension, which is an unstable dispersion system. In order to improve the dispersibility and stability of the existing inkjet printing ink, chelating agents or surfactants are added. Although it can improve the dispersibility and stability of the ink, the addition of chelating agents and surfactants will have an adverse effect on the subsequent preparation of the membrane electrode and even the performance of the battery. Summary of the invention

[0005] Based on the above background, the present invention prepares a highly stable inkjet printing ink for fuel cells and water electrolysis without adding any components that affect the performance of the electrode. All materials are added in one step, the preparation process is simple, the ink does not settle for a long time at room temperature, and can be printed continuously in the ink cartridge without problems such as nozzle blockage and unsmooth printing. The membrane electrode prepared by inkjet printing the ink of the present invention on a proton exchange membrane exhibits good electrochemical properties after drying, which is better than traditional inks.

[0006] The technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a membrane electrode inkjet printing ink, the ink comprising a catalyst, a solvent, a binder and a resin solution;

[0008] In the ink, the mass ratio of the catalyst, the solvent, the binder, and the resin in the resin solution is 1:30-70:5-50:0.1-4;

[0009] The solvent is one or more of isopropanol, n-propanol, ethanol or water.

[0010] The adhesive includes one or more of ethylene glycol, propylene glycol, polyethylene glycol, and glycerol.

[0011] Furthermore, in the above technical solution, the catalyst is a carbon-supported catalyst, an iridium-based catalyst, a platinum-based catalyst, a ruthenium-based catalyst or a palladium-based catalyst.

[0012] Furthermore, in the above technical solution, the resin includes perfluorosulfonic acid resin, PTFE emulsion, PVDF emulsion or a resin having a quaternary ammonium, imidazole, benzimidazole, pyridine, piperidine, guanidine or quaternary phosphonium ion functional group on the side chain.

[0013] In a second aspect, the present invention provides a method for preparing a membrane electrode inkjet printing ink, comprising the following steps:

[0014] The solvent, the adhesive and the resin solution are mixed uniformly according to the above mass ratio to obtain a mixed solution;

[0015] After the catalyst is mixed with the mixed solution, mechanical stirring and ultrasonic treatment are performed to obtain a membrane electrode catalyst layer inkjet printing ink with high stability and high dispersibility.

[0016] Furthermore, in the above technical solution, the stirring time is 0.5-48h; the ultrasonic time is 0.5-48h.

[0017] The high-stability and high-dispersibility membrane electrode catalyst layer inkjet printing ink does not produce sedimentation when left standing for a long time under natural light at room temperature.

[0018] In a third aspect, the present invention provides a membrane electrode, which is prepared by an inkjet printing method using the above-mentioned inkjet printing ink.

[0019] In a fourth aspect, the present invention provides a method for preparing a membrane electrode, comprising the following steps: inkjet printing the above-mentioned inkjet printing ink on a proton exchange membrane, an anion exchange membrane or a substrate for transfer, and drying to obtain a membrane electrode.

[0020] Furthermore, in the above technical solution, the substrate includes a polytetrafluoroethylene substrate and a polyethylene substrate.

[0021] In a fifth aspect, the present invention provides an application of a membrane electrode, wherein the membrane electrode is applied to an electrochemical device in the field of a fuel cell or water electrolysis.

[0022] Beneficial Effects

[0023] 1. The formulation of the inkjet printing ink for the membrane electrode catalyst layer provided by the present invention does not add any components that may affect the activity of the catalyst, nor does it require any post-processing steps, and the process is simple.

[0024] 2. The membrane electrode catalyst layer inkjet printing ink formula provided by the present invention is added with an adhesive, and the adhesive is selected from one or more of ethylene glycol, propylene glycol, polyethylene glycol, and glycerol, and the solvent is selected from one or more of isopropanol, n-propanol, ethanol, or water with a large polarity. The van der Waals force is large, which can make the adhesive achieve a better dispersion effect in the aqueous solution and improve the stability of the ink. Among them, water has the largest polarity and better performance, and can play an anti-sedimentation role. The prepared ink has a viscosity range of 1-50mPa·s and a surface tension of 50-150mN / m, and is suitable for a variety of inkjet printing nozzles and inkjet printing modes.

[0025] 3. The preparation process of the inkjet printing ink provided by the present invention is simple. All solutions are mixed at one time and then the catalyst is added, which avoids the tedious steps of multiple additions and the agglomeration problem caused by the uneven distribution of local solutions caused by multiple additions. It is conducive to obtaining a catalyst ink with high dispersibility and stability. There is no sedimentation when it is left standing for a long time at room temperature, while the traditional inkjet printing ink will settle when it is left standing for more than 5 hours.

[0026] 4. The membrane electrode prepared by the membrane electrode catalyst layer inkjet printing ink provided by the present invention has good performance and is superior to the membrane electrode prepared by traditional inkjet printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a diagram showing the ink status of the membrane electrode catalyst layer inkjet printing ink of Example 1 of the present invention after it has been left standing at room temperature for three months.

[0028] Figure 2 The following is a picture of the working process of the inkjet printer used in the present invention.

[0029] Figure 3 The ink prepared in Example 1 of the present invention is used to print one layer (A) and three layers (B) of the catalytic layer.

[0030] Figure 4 This is a scanning electron microscope comparison diagram of the catalytic layer (A) prepared by inkjet printing in Example 1 of the present invention and the catalytic layer prepared by the traditional spraying process (B).

[0031] Figure 5 This is a comparison chart of polarization curves of the membrane electrode catalyst layer inkjet printing ink and the membrane electrode prepared by the spraying process in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The following non-limiting embodiments may enable a person skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0033] The catalyst, solvent, adhesive and resin solution used in the embodiments of the present invention are all commercially available products.

[0034] Comparative Example 1

[0035] The fuel cell spray ink comprises: 60 mg of a catalyst (40 wt % Pt / C), a solvent (isopropanol), and a resin solution (5 wt % Nafion) in a mass ratio of 1:50 and 1:6.25, respectively.

[0036] The preparation method of the ink is:

[0037] According to the above ratio, 40wt% Pt / C was first dissolved in isopropanol, and ultrasonicated in a water bath at 5°C for 30 minutes. Then, 5wt% Nafion solution was added, and then probe ultrasonicated for 30 minutes at a power of 30% to obtain the traditional inkjet printing ink for the fuel cell of this comparative example.

[0038] The conventional ink of this comparative example was sprayed on both sides of the Asahi Kasei 15 μm 7201 proton exchange membrane to prepare a fuel cell membrane electrode. The membrane electrode cathode platinum loading was 0.05 mg cm -2 , the anode platinum loading is 0.15 mg cm -2 The test conditions of membrane electrode are: the effective area of ​​the battery is 4cm 2 , 60℃, relative humidity 25%, H 2 / Air flow is 0.1 / 0.8L / min, and the pressure is 0MPa.

[0039] Example 1

[0040] The membrane electrode inkjet printing ink comprises: a catalyst of 40 wt% Pt / C 60 mg, a solvent of deionized water, a binder of ethylene glycol and a resin solution of 5 wt% perfluorosulfonic acid resin (Nafion) in a mass ratio of 1:40, 1:10 and 1:6.25 respectively (equivalent to a mass ratio of the catalyst to the resin in the resin solution of 5 wt% perfluorosulfonic acid resin of 1:0.3125).

[0041] The preparation method of the ink is:

[0042] Deionized water, ethylene glycol and 5 wt% perfluorosulfonic acid resin (Nafion) solution were mixed uniformly according to the above proportions, and then added to 40 wt% Pt / C catalyst, and ultrasonicated in a water bath at 5°C for 1 h. Then, probe ultrasonicated for 30 min at a power of 30% and a rated power of 300 W to obtain the membrane electrode inkjet printing ink of this example.

[0043] The membrane electrode inkjet printing ink of this example was printed on both sides of the Asahi Kasei 15 μm 7201 composite membrane, and after drying, a fuel cell membrane electrode was obtained. The platinum loading of the membrane electrode cathode was 0.05 mg cm -2 , the anode platinum loading is 0.15 mg cm -2 The test conditions of membrane electrode are: the effective area of ​​the battery is 4cm 2 , tested at 60℃, relative humidity 25%, H 2 / Air flow is 0.1 / 0.8L / min, and the pressure is 0MPa.

[0044] The ink state of the inkjet printing ink after standing at room temperature for three months is shown in the figure below. Figure 1As shown, the ink does not settle. Ink is injected into the ink cartridge and a layer of ( Figure 3 A) and three layers ( Figure 3 B) The actual picture is as follows Figure 3 As shown in the figure, the printing process is smooth without blocking the nozzle, and the ink is evenly distributed. The scanning electron microscope comparison of the catalyst layer prepared by inkjet printing and traditional spraying process is shown in the figure. Figure 4 As shown. Figure 4 , inkjet printed catalyst layer ( Figure 4 A) The flatness is significantly better than that of traditional catalyst layers ( Figure 4 B), which is more conducive to charge transfer, thereby improving battery performance.

[0045] The polarization curve of the membrane electrode is shown in Figure 5 .Depend on Figure 5 , at 60℃, relative humidity 25%, H 2 Under the test conditions of air flow rate of 0.1 / 0.8L / min and pressure of 0MPa, the highest power density of membrane electrode prepared by traditional ink is 533mW·cm -2 @1236mA·cm -2 The highest power density of the membrane electrode prepared by inkjet printing ink is 703mW·cm -2 @1716mA·cm -2 , which is higher than the membrane electrode prepared by traditional ink. Therefore, the performance of the membrane electrode prepared by high-stability inkjet printing ink is better than that of the membrane electrode prepared by traditional ink.

[0046] Comparative Example 2

[0047] On the basis of the inkjet printing ink obtained in Example 1, butyl butyrate chelating agent was added and ultrasonic dispersion was performed for 30 minutes. The mass ratio of the chelating agent to the catalyst was 11:1.

[0048] The polarization curve of the membrane electrode is shown in Figure 5 .Depend on Figure 5 , at 60℃, relative humidity 25%, H 2 Under the test conditions of air flow rate of 0.1 / 0.8L / min and pressure of 0MPa, the maximum power density of the membrane electrode after the introduction of the chelating agent was 664mW·cm -2 @1676mA·cm -2 , slightly lower than Example 1. This is because the addition of the chelating agent will affect the structure of the catalytic layer.

[0049] Comparative Example 3

[0050] The catalyst was dispersed in a mixed solution of deionized water as a solvent and ethylene glycol as an adhesive. After ultrasonic treatment for 30 minutes, a 5% perfluorosulfonic acid resin (Nafion) solution was added for ultrasonic dispersion. The other steps were the same as those in Example 1.

[0051] The catalyst ink obtained in Comparative Example 3 showed obvious agglomeration and could not meet the requirements of inkjet printing.

[0052] Example 2

[0053] The solvent in Example 1 was replaced with isopropanol, and the other steps and conditions were the same as in Example 1.

[0054] The ink of Example 1 can stand for a long time without settling, while the ink of Example 2 shows slight settling after standing for 36 hours. Its stability is slightly lower than that of Example 1, but it can still meet the requirements of inkjet printing.

[0055] Example 3

[0056] The solvent in Example 1 was replaced with n-propanol, and the other steps and conditions were the same as in Example 1.

[0057] The ink of Example 1 can stand for a long time without settling, while the ink of Example 3 shows slight settling after standing for 36 hours. Its stability is slightly lower than that of Example 1, but it can still meet the requirements of inkjet printing.

[0058] Example 4

[0059] The resin solution in Example 1 was replaced with an anion resin solution having terphenyl as the main chain and N-methyl-4-piperidone as the functional group, and the Asahi Kasei 15 μm 7201 composite membrane was replaced with an anion exchange membrane made of the above anion resin. The other steps and conditions were the same as in Example 1.

[0060] The prepared ink can be left standing for a long time at room temperature without settling, meeting the needs of inkjet printing.

Claims

1. A method for preparing membrane electrode inkjet printing ink, characterized in that: The method comprises the following steps: uniformly mixing a solvent, an adhesive and a resin solution to obtain a mixed solution; Mixing the catalyst with the mixed solution, stirring, and ultrasonicating to obtain the membrane electrode inkjet printing ink; The ink is composed of a catalyst, a solvent, a binder and a resin solution; In the ink, the mass ratio of the catalyst, the solvent, the adhesive and the resin in the resin solution is 1:30-70:5-50:0.1-4; the solvent is water; and the adhesive includes one or more of ethylene glycol, propylene glycol, polyethylene glycol and glycerol.

2. The method for preparing membrane electrode inkjet printing ink according to claim 1, characterized in that: The catalyst is a carbon-supported catalyst, an iridium-based catalyst, a platinum-based catalyst, a ruthenium-based catalyst or a palladium-based catalyst.

3. The method for preparing membrane electrode inkjet printing ink according to claim 1, characterized in that: The resin includes perfluorosulfonic acid resin, PTFE emulsion, PVDF emulsion or resin with quaternary ammonium, imidazole, benzimidazole, pyridine, piperidine, guanidine or quaternary phosphorus ion functional groups on the side chain.

4. The method for preparing membrane electrode inkjet printing ink according to claim 1, characterized in that: The stirring time is 0.5-48h; the ultrasonic time is 0.5-48h.

5. A membrane electrode, characterized in that: The membrane electrode is prepared by inkjet printing using the ink prepared by the preparation method according to any one of claims 1 to 3.

6. A method for preparing a membrane electrode, characterized in that: The method comprises the following steps: inkjet printing the ink prepared by the preparation method according to any one of claims 1 to 3 on a proton exchange membrane, an anion exchange membrane or a substrate, and performing a drying process to obtain a membrane electrode.

7. An application of a membrane electrode, characterized in that: The membrane electrode according to claim 5 is applied to an electrochemical device in the field of fuel cells or water electrolysis.

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