A spraying preparation method for an electrode and its application in a fuel cell

Abstract

The present invention discloses a method for spraying an electrode and its application in a fuel cell, belonging to the field of battery electrode preparation. The technical solution is as follows: a method for spraying an electrode, comprising the following steps: step S1: pre-treating a substrate; step S2: fully grinding a load material, a dispersant, and a binder in a mass ratio of (70-160): (20-60): (2-5) to prepare a mixed slurry; step S3: adding the mixed slurry to a gas spray gun, pressurizing it to 0.1-0.3 MPa at 18°C-25°C, and spraying it onto the substrate pre-treated in step S1; step S4: drying the substrate after spraying the mixed slurry in step S3 to obtain an electrode. The beneficial effects of the present invention are as follows: the present invention provides a method for spraying an electrode, which is simple and easy to operate, has a high bonding strength between the coating and the substrate, and is electrochemically stable when applied to a fuel cell.

Description

Technical Field

[0001] The present invention relates to the technical field of battery electrode preparation, and in particular to a spraying preparation method of an electrode and its application in a fuel cell. Background Art

[0002] With the rapid development of the national economy, humanity's demand for energy is increasing. Excessive development and utilization of fossil fuels has led to global energy shortages and severe environmental pollution. Therefore, the development of green energy technologies is urgent. Fuel cells (FCs) are such green energy devices. They differ fundamentally from traditional power generation methods in that both the fuel and oxidant are externally sourced. As long as the fuel and oxidant are continuously supplied, power generation can continue without capacity limitations. They directly convert the chemical energy of the fuel and oxidant into electrical energy. This conversion process does not involve combustion, reducing the number of energy conversion cycles. Therefore, they can overcome the limitations of the Carnot cycle and achieve higher efficiency. Furthermore, they operate with very low emissions, are quiet and noiseless, and can be used with a wide range of fuels, offering great development and application prospects. Among them, solid oxide fuel cells (SOFCs) offer advantages over other fuel cells, such as high efficiency, low pollution, and strong fuel adaptability. Their all-solid-state structure avoids the corrosion and electrolyte loss problems associated with using liquid electrolytes. SOFCs primarily consist of three components: an anode, an electrolyte, and a cathode. The electrode has a porous structure and is the site where the fuel and oxidant undergo oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR). The design and development of new electrode materials and the study of electrode reaction processes have always been research hotspots in the SOFC field.

[0003] At the same time, in order to simplify the preparation process and structure of traditional three-component fuel cells, a semiconductor ion fuel cell based on the band alignment theory was developed. Its semiconductor ion material functional layer has multiple transmission paths for oxygen ions, protons and electrons / holes, and has semiconductor properties and ion conduction characteristics. It also has electrolyte functions and electrode functions. The ion-electron coupling effect generated by the built-in electric field of the semiconductor ion heterostructure greatly enhances the ion conductivity. The enhancement mechanism of HOR and ORR in the electrochemical reaction process can significantly promote ion transport and catalytic efficiency, and can achieve better performance than traditional fuel cells. It is simple to prepare, has low manufacturing cost, and is more suitable for operating temperatures in the low temperature range of 300℃ to 600℃.

[0004] During the existing semiconductor ion fuel cell electrode preparation process, the load material is applied to the substrate by brushing. However, during the mold installation and dry pressing process for the semiconductor ion fuel cell preparation and subsequent electrochemical testing, the load material is prone to fall off, affecting the reliability of the battery performance test. Therefore, to prevent the load material from falling off during the preparation and testing of the semiconductor ion fuel cell and affecting the battery performance test, it is imperative to find a new electrode spray preparation method that can ensure that the load material adheres more firmly to the substrate. Summary of the Invention

[0005] In order to solve the above problems in the prior art, the present invention provides a spraying method for preparing an electrode which is simple and easy to operate, has high bonding strength between the coating and the substrate, and is electrochemically stable.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides a spraying method for preparing an electrode, which is characterized by comprising the following steps:

[0007] Step S1: pre-treating the substrate;

[0008] Step S2: fully grinding the load material, dispersant and binder in a mass ratio of (70-160): (20-60): (2-5) to prepare a mixed slurry;

[0009] Step S3: adding the mixed slurry into a gas spray gun, pressurizing it to 0.1-0.3 MPa at 18-25° C., and spraying it onto the substrate pretreated in step S1;

[0010] Step S4: drying the substrate after spraying the mixed slurry in step S3 to obtain an electrode.

[0011] Furthermore, the substrate is a two-dimensional metal material substrate or a three-dimensional metal material substrate or a carbon substrate.

[0012] Furthermore, the substrate is foamed nickel or foamed copper.

[0013] Furthermore, the pores in the substrate have a diameter of 0.1 mm to 0.6 mm, and the thickness of the substrate is 1.2 mm to 1.6 mm.

[0014] Furthermore, the load material is Ni 0.8 Co 0.15 Al 0.05 LiO 2-δ 、Ni 0.8 Co 0.1 Mn 0.1 LiO 2-δ One or more of .

[0015] Furthermore, the dispersant is terpineol.

[0016] Furthermore, the binder is one or more of acrylate and ethyl cellulose.

[0017] Furthermore, the drying step in step S4 is as follows: firstly drying the mixed slurry in air at room temperature until the mixed slurry solidifies, and then drying it in an oven at 120° C. to 130° C. for 30 min to 60 min.

[0018] Furthermore, the step of pre-treating the substrate in step S1 is:

[0019] Step S101: immersing the substrate in deionized water and anhydrous ethanol in sequence to remove impurities;

[0020] Step S102: ultrasonically clean the substrate after impurities removal for 10 to 20 minutes, and then place it in an oven at 50° C. to 70° C. and dry it for 1 to 2 hours.

[0021] An application of the spraying preparation method of the electrode in semiconductor ion fuel cells.

[0022] The beneficial effects of the present invention are:

[0023] (1) The present invention adopts air spraying technology. Compared with the brush coating method, the coating prepared by air spraying technology has high bonding strength, simple process and easy operation, and the large-area coating prepared by continuous spraying has better continuity and uniformity.

[0024] (2) The present invention uses a mixed slurry made by blending a binder and a load material. The binder can improve the interfacial bonding strength between the substrate and the coating, and between the dispersed material particles in the coating, avoid the powdering of the electrode sheet, maintain the integrity of the electrode structure, and improve the electrochemical stability of the battery.

[0025] (4) The electrode provided by the present invention is used as a fuel cell electrode material in the form of a symmetrical electrode. Taking the nickel foam-NCAL electrode prepared by the preparation method of the present invention as an example, when the semiconductor ion composite material powder is used as the functional layer of the fuel cell, its performance is enhanced, and a peak power density of 691.87 mW cm is shown at 520 ° C. -2 , the open circuit voltage is 0.965V.

[0026] (5) The electrodes prepared by the preparation method provided by the present invention have high load stability, and the mass loss rate after multiple drop tests is very small or almost unchanged. The present invention has the advantages of low preparation cost, easy scale-up, easy to obtain a continuous and uniform coating, and effectively avoids powder loss of the electrode sheet, maintains the integrity of the electrode structure, and improves the electrochemical stability of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1Surface characteristic images of the electrodes in Example 1 and Comparative Example 1 of the present invention and SEM cross-sectional images of the interface between the substrate and the coating: (a) is a surface characteristic image of the control electrode in the control example, (b) is a surface characteristic image of the nickel foam-NCAL electrode in Example 1, (c) is a SEM image of the control electrode in the control example, and (d) is a SEM image of the nickel foam-NCAL electrode in Example 1;

[0028] Figure 2 This is a comparison chart of the weight loss rate of the electrodes after different dropping times in Example 1 of the present invention and Comparative Example 1;

[0029] Figure 3 The IV and IP characteristic curves of the batteries prepared in Example 2 of the present invention and Comparative Example 2 measured at 520°C are shown;

[0030] Figure 4 The AC impedance spectra of the batteries prepared in Example 2 of the present invention and Comparative Example 2 were measured at 520°C. DETAILED DESCRIPTION

[0031] In order to clearly illustrate the technical features of this solution, this solution is described below through specific implementation methods.

[0032] See also Figure 1 The embodiment of the present invention provides a method for spraying and preparing an electrode, which is characterized by comprising the following steps:

[0033] Step S1: pre-treating the substrate;

[0034] Step S2: fully grinding the load material, dispersant and binder in a mass ratio of (70-160): (20-60): (2-5) to prepare a mixed slurry;

[0035] Step S3: adding the mixed slurry into a gas spray gun, pressurizing it to 0.1-0.3 MPa at 18-25° C., and spraying it onto the substrate pretreated in step S1;

[0036] Step S4: Drying the substrate after spraying the mixed slurry in step S3 to obtain an electrode.

[0037] The electrode spraying preparation method provided in this embodiment can form a uniform and smooth coating on the substrate compared to the traditional brushing method, and can enhance the adhesion of the coating, making the slurry less likely to fall off. In addition, the spraying method is more efficient. The terpineol in the mixed slurry also functions as a pore-forming agent, forming more micropores on the electrode surface, allowing gas to easily pass through and reach the three-phase interface to undergo a chemical reaction.

[0038] Furthermore, the substrate is a two-dimensional metal material substrate or a three-dimensional metal material substrate or a carbon substrate material: two-dimensional metal materials such as titanium foil, copper foil and iron-nickel foil are commonly used electrode current collectors in the laboratory and can be directly used as the substrate of the self-supporting electrode; three-dimensional metal materials have a good three-dimensional network structure and rich macroscopic porosity, and are ideal self-supporting electrode substrate materials; in addition, other self-supporting substrate materials such as carbon felt and graphene can also be used as the substrate in the present invention.

[0039] Furthermore, the substrate is nickel foam or copper foam. Three-dimensional metal materials such as nickel foam and copper foam have a good three-dimensional network structure and rich macroporosity, making them ideal self-supporting electrode substrate materials. Among them, nickel foam has a suitable three-dimensional network structure, high conductivity, and rich macroporosity. It is the most common three-dimensional metal material. Nickel foam is used as a substrate to support the electrode and collect current, making it a preferred substrate material in the present invention.

[0040] Furthermore, the pores in the substrate have a diameter of 0.1 mm to 0.6 mm, and the thickness of the substrate is 1.2 mm to 1.6 mm.

[0041] Furthermore, the loading material is Ni 0.8 Co 0.15 Al 0.05 LiO 2-δ 、Ni 0.8 Co 0.1 Mn 0.1 LiO 2-δ One or more of .

[0042] Furthermore, the dispersant is terpineol. In the spraying preparation method of the electrode of the present invention, terpineol not only acts as a dispersant, but also has the function of a binder, further improving the bonding strength between the coating and the substrate.

[0043] Furthermore, the binder is one or more of acrylate or ethyl cellulose; wherein the acrylate binder has excellent adhesion and flexibility, can avoid the powdering phenomenon of the electrode sheet, maintain the integrity of the electrode structure, and improve the electrochemical stability of the battery, and is the preferred binder of the present invention.

[0044] When the load material, dispersant and binder are respectively selected as Ni 0.8 Co 0.15 Al 0.05 LiO 2-δ , terpineol and acrylate, the mass ratio of the load material, the dispersant and the binder in preparing the mixed slurry in step S2 is (120-160): (40-60): (2-5);

[0045] When the load material, dispersant and binder are respectively selected as Ni 0.8 Co0.15 Al 0.05 LiO 2-δ , terpineol and ethyl cellulose, the mass ratio of the loading material, the dispersant and the binder when preparing the mixed slurry in step S2 is (70-80): (20-30): (2-4).

[0046] Furthermore, the drying step in step S4 is as follows: firstly drying the mixed slurry in air at room temperature until the mixed slurry solidifies, and then drying it in an oven at 120° C. to 130° C. for 30 min to 60 min to accelerate the drying process efficiency.

[0047] Furthermore, the steps of pre-treating the substrate in step S1 are:

[0048] Step S101: immersing the substrate in deionized water and anhydrous ethanol in sequence to remove impurities;

[0049] Step S102: ultrasonically clean the substrate after impurities removal for 10 to 20 minutes, and then place it in an oven for drying at 50° C. to 70° C. for 1 to 2 hours.

[0050] Nickel foam has a three-dimensional network macroporous structure, can provide high specific surface area and electrical conductivity and has good chemical stability under a variety of liquid environments, and the material source is abundant and cheap. Acrylate binder has excellent adhesion on metal and metal oxide surfaces, which is conducive to enhancing the interface bonding firmness of load material and nickel foam substrate. Example 1 uses nickel foam as substrate to carry out spray coating of load material, and the preparation process is simple and controllable. Adhesive and air spraying mode are adopted to realize that nickel foam surface mixed slurry adheres, and the interface bonding strength of nickel foam-load material electrode is improved.

[0051] Example 1

[0052] A spraying preparation method for an electrode, characterized in that it comprises the following steps:

[0053] Step S1: Pre-treating the nickel foam substrate: The average pore size of the nickel foam is about 175 μm, and the thickness is 1.5 mm. The nickel foam is cut to the required size of φ14 mm for preparing a semiconductor ion fuel cell. Specifically, the nickel foam is first immersed in deionized water and anhydrous ethanol in sequence to remove impurities. Then, the impurity-removed nickel foam is ultrasonically cleaned for 10 minutes, and then placed in an oven to dry at 60°C for 1 hour to 2 hours.

[0054] Step S2: Ni 0.8 Co 0.15 Al 0.05 LiO 2-δ , terpineol and acrylate are placed in an agate mortar and fully ground into a mixed slurry;

[0055] Step S3: adding the mixed slurry into a gas spray gun, maintaining a filling rate of 30% to 50%, and spraying it under pressure at room temperature onto the foamed nickel substrate pretreated in step S1;

[0056] Step S4: Drying the substrate after spraying the mixed slurry in step S3 to obtain an electrode. 0.8 Co 0.15 Al 0.05 LiO 2-δ Also known as NCAL, the electrode prepared in this embodiment is hereinafter referred to as a nickel foam-NCAL electrode. The specific drying treatment steps are: first, place it on a zirconia plate in air at room temperature to dry until the mixed slurry solidifies and the slurry on the nickel foam no longer penetrates into the zirconia plate, and then dry it in an oven at 120°C for 30 minutes to 60 minutes.

[0057] The surface of the prepared nickel foam-NCAL electrode was observed and characterized by SEM. The surface image of the nickel foam-NCAL electrode can be found in Figure 1 (a) Figure 1 (b) It can be seen that the electrodes prepared by the two methods both exhibit a porous structure, and the powder scattered on the sample plate shows that the electrode loading material NCAL with the addition of acrylate binder is more solid. The cross-sectional SEM image of the nickel foam-NCAL electrode is shown in Figure 1 (c) Figure 1 (d), where the NCAL particles are spherical with diameters ranging from a few microns to tens of microns. It can also be seen from the figure that the interface between NCAL and the nickel foam substrate is very compact.

[0058] Example 2

[0059] A semiconductor ion fuel cell includes an electrode prepared by the electrode spraying preparation method. In this embodiment, the semiconductor ion fuel cell includes the nickel foam-NCAL electrode prepared in Example 1;

[0060] A method for preparing a semiconductor ion fuel cell comprises the following steps:

[0061] Weigh a certain weight of semiconductor ion composite material powder, sandwich it between two electrodes and load it into a battery mold with a diameter of 14 mm. That is, put the nickel foam-NCAL electrode, semiconductor ion composite material powder, and nickel foam-NCAL electrode into the battery mold in this order;

[0062] The loaded mold was placed in a powder tablet press and the semiconductor ion fuel cell was obtained by dry pressing at a pressure of 200 MPa for 5 minutes. The effective area of ​​the semiconductor ion fuel cell prepared in this example was 0.64 cm 2 .

[0063] Comparative Example 1

[0064] A nickel foam-NCAL electrode without adding a binder was prepared as a control electrode. The preparation method of the nickel foam-NCAL electrode without adding a binder was the same as that of Example 1. The difference from Example 1 was that the binder acrylate was not added to the mixed slurry.

[0065] The nickel foam-NCAL electrode and the control electrode were dropped freely from the same height (1m) parallel to the ground to the same hard ground, and their mass loss rates under different dropping times were compared. Three groups of samples of the control electrode and the nickel foam-NCAL electrode were taken to calculate the average mass loss rate.

[0066] from Figure 2 It can be seen that under the same number of drops, the mass loss rate of the control electrode is much greater than that of the nickel foam-NCAL electrode, while the mass loss of the nickel foam-NCAL electrode remains almost unchanged after multiple drop tests.

[0067] Comparative Example 2

[0068] Based on the nickel foam-NCAL electrode without adding a binder, a control semiconductor ion fuel cell was prepared using the same method as in Example 2, i.e., the nickel foam-NCAL electrode in Example 2 was replaced with the nickel foam-NCAL electrode without adding a binder. The effective area of ​​the control semiconductor ion fuel cell was 0.64 cm 2 .

[0069] The semiconductor ion fuel cell in Example 2 and the control semiconductor ion fuel cell in Comparative Example 2 were fueled with hydrogen at a flow rate of 80 mL / min. -1 ; Air is the oxidant, the flow rate is 100mLmin -1 The test temperature of the battery is 520℃, and the electrochemical performance test is carried out. The test process is as follows: (1) Turn on the heating furnace and set the required heating process; (2) Place the prepared semiconductor ion fuel cell or the control battery semiconductor ion fuel cell in the battery fixture and clamp it to ensure that there is no obvious gap, then place the fixture in the heating furnace and heat it with the furnace, and let air in during the heating process; (3) After the heating is completed, introduce hydrogen and record the experimental data (open circuit voltage, current, power density, etc.), and then process its IVP and EIS curves, such as Figure 3 、 Figure 4 shown.

[0070] like Figure 3The IV and IP curves of the semiconductor ion fuel cell and the control semiconductor ion fuel cell are shown. It can be seen from the figure that both symmetrical electrodes can achieve excellent electrode functions, showing good current density and high open circuit voltage. The control semiconductor ion fuel cell provides 638.53mWcm at 520℃. -2 The maximum power density of 1.57 mW cm-3 and the open-circuit voltage of 0.891 V were achieved. Interestingly, the semiconductor ion fuel cell showed significantly enhanced performance compared with the control semiconductor ion fuel cell, exhibiting a peak power density of 691.87 mW cm-3 at 520 °C. -2 , the open circuit voltage is 0.965V.

[0071] In the EIS diagram, the intercept of the impedance spectrum arc with the real axis in the high-frequency region is the ohmic resistance Ro, which mainly includes the ohmic resistance of the electrolyte, the ohmic resistance of the electrode, and the ohmic resistance related to the interface contact; the intercept of the impedance spectrum arc on the real axis between the high-frequency band and the low-frequency band is the polarization resistance Rp on the electrode related to fuel diffusion and electrode reaction. Figure 4 It can be clearly seen that the Ro and Rp of the semiconductor ion fuel cell are slightly lower than those of the control semiconductor ion fuel cell.

[0072] The system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units. They may be located in one place or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of this embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0073] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for spraying and preparing an electrode of a semiconductor ion fuel cell, characterized in that: The following steps are involved: Step S1: pre-treating the substrate; Step S2: fully grinding the load material, dispersant and binder in a mass ratio of (70-160): (20-60): (2-5) to prepare a mixed slurry; Step S3: adding the mixed slurry into a gas spray gun, pressurizing it to 0.1-0.3 MPa at 18-25° C., and spraying it onto the substrate pretreated in step S1; Step S4: drying the substrate after spraying the mixed slurry in step S3 to obtain an electrode; The load material is Ni 0.8 Co 0.15 Al 0.05 LiO 2-δ 、Ni 0.8 Co 0.1 Mn 0.1 LiO 2-δ One or more of; The dispersant is terpineol; The binder is one or more of acrylate or ethyl cellulose.

2. The method for preparing an electrode by spraying according to claim 1, wherein: The substrate is a two-dimensional metal material substrate or a three-dimensional metal material substrate or a carbon substrate.

3. The method for preparing an electrode by spraying according to claim 1, wherein: The substrate is foamed nickel or foamed copper.

4. The method for preparing an electrode by spraying according to claim 3, characterized in that: The pores in the substrate have a pore diameter of 0.1 mm to 0.6 mm, and the thickness of the substrate is 1.2 mm to 1.6 mm.

5. The method for preparing an electrode by spraying according to claim 1, wherein: The drying process in step S4 is as follows: firstly drying the mixed slurry in air at room temperature until the mixed slurry solidifies, and then drying the mixed slurry in an oven at 120° C. to 130° C. for 30 min to 60 min.

6. The method for preparing an electrode by spraying according to claim 1, characterized in that: The steps of pre-treating the substrate in step S1 are: Step S101: immersing the substrate in deionized water and anhydrous ethanol in sequence to remove impurities; Step S102: ultrasonically clean the substrate after impurities removal for 10 to 20 minutes, and then place it in an oven for drying at 50° C. to 70° C. for 1 to 2 hours.

7. An electrode material, characterized in that The method according to any one of claims 1 to 6 is used for preparation.

8. A semiconductor ion fuel cell, characterized in that: Contains the electrode material according to claim 7.

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