Low-temperature proton ceramic fuel cell composite catalytic material as well as preparation and application thereof

Abstract

The invention belongs to the technical field of fuel cells, and particularly relates to a low-temperature proton ceramic fuel cell composite catalytic material as well as preparation and application thereof. By doping the Cs with BaCe0. 3Fe0. 7O3-delta, the surface proton acid site concentration is remarkably improved, and the hydration capability and the proton conduction performance are optimized, so that the proton ceramic fuel cell can realize higher power density (1.62 W / cm < 2 >) and current density (-2.73 A / cm < 2 >) under a low-temperature condition (600-700 DEG C), the polarization resistance (Rp) is as low as 0.039 omegacm < 2 >, and the proton ceramic fuel cell can stably run for more than 100 hours in an environment of 3% H2O; obvious performance reduction does not occur, and efficient and stable operation of the proton ceramic fuel cell at low temperature is realized. The material is simple in preparation process, suitable for large-scale production and wide in application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fuel cells, and particularly relates to a low-temperature proton ceramic fuel cell composite catalytic material and a preparation and application thereof. BACKGROUND

[0002] Proton ceramic fuel cells (PCFC) have attracted much attention due to their high energy conversion efficiency and low carbon dioxide emission, but their performance decreases significantly at low temperatures, mainly due to the slow kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Traditional cobalt-based cathode materials have excellent catalytic activity, but have problems of mismatched thermal expansion coefficient (TEC) and interface stability. In recent years, cobalt-iron-based perovskite materials (such as BaFeO 3-δ ) have become a research hotspot due to their excellent oxygen ion conductivity and stability, but the distribution of surface acid sites is not ideal, which limits the proton conduction and catalytic activity.

[0003] In the prior art, A-site doping (such as Sr, Ca) can regulate the material performance, but can easily cause lattice shrinkage or Sr segregation. Alkali metal (Li, Na, K) doping can reduce Lewis acid sites (LAS), but its volatility and small ion radius limit its application.

[0004] Traditional perovskite materials have poor proton conduction performance at low temperatures (such as 600 ℃ to 700 ℃), resulting in low power density of fuel cells and low current density of electrolytic cells. For example, the maximum power density of many existing perovskite materials at 700 ℃ can only reach 1.2 W / cm 2 , which is difficult to meet the demand for high energy conversion in practical applications. Existing materials usually have a high content of Lewis acid sites (LAS) and a low content of Bronsted acid sites (BAS). LAS can accept electrons, but has poor catalytic activity for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), while BAS plays an important role in water adsorption and dissociation, which can significantly improve the proton conduction performance. Therefore, the distribution of surface acid sites of existing materials is not conducive to the efficient transport of protons and reaction kinetics. Existing materials are easily corroded by water vapor and oxygen during long-term operation, resulting in performance degradation. For example, some materials will have obvious performance degradation after running in a 3% H2O environment for only a few tens of hours, which cannot meet the requirements for long-term stability in practical applications. Moreover, the preparation process of existing high-performance materials is often complex and costly, which is difficult to mass-produce. For example, some materials need to be prepared by complex coprecipitation or sol-gel method, and the preparation conditions are harsh, which limits their industrial application.

[0005] Therefore, how to design a kind of catalytic material of proton ceramic fuel cell, which can improve the concentration of surface proton acid sites, optimize hydration capacity and proton conduction performance, improve electrochemical performance under low temperature conditions and simplify preparation process is the technical problem to be solved by the present application. SUMMARY

[0006] In order to overcome the shortcomings of the prior art, the present application provides a low-temperature proton ceramic fuel cell composite catalytic material and its preparation and application. 0.3 Fe 0.7 O 3-δ , which significantly improves the concentration of surface proton acid sites, optimizes hydration capacity and proton conduction performance, and is suitable for low-temperature (600-700 °C) proton ceramic fuel cell PCFC and reversible proton ceramic battery (R-PCEC).

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is: The first aspect of the present application provides a low-temperature proton ceramic fuel cell composite catalytic material, the chemical formula of the composite catalytic material is Ba 0.95 Cs 0.05 Ce 0.3 Fe 0.7 O 3-δ The composite catalytic material has a 69 wt% cubic CP and a 31 wt% orthorhombic OP double-phase perovskite structure.

[0008] Further, the thermal expansion coefficient of the composite catalytic material is 16.16×10 -6 K -1 , which matches with the electrolyte BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ (BZCYY).

[0009] The second aspect of the present application provides a preparation method of the above-mentioned low-temperature proton ceramic fuel cell composite catalytic material, which comprises the following steps: (1) according to Ba 0.95 Cs 0.05 Ce 0.3 Fe 0.7 O 3-δ The stoichiometric ratio in the molecular formula is taken Ba(NO3)2, CsNO3, Ce(NO3)3·6H2O, Fe(NO3)3·9H2O, dissolved in deionized water; (2) add citric acid, heat and stir to form a gel, and dry to obtain a precursor; (3) The precursor is calcined to obtain a low-temperature proton ceramic fuel cell composite catalytic material, namely BCCF powder.

[0010] Further, in step (2), the molar ratio of the citric acid to the metal ions is 1.5:1.

[0011] Further, in step (2), the heating temperature is 80 o C.

[0012] Further, in step (2), the drying temperature is 120 o C.

[0013] Further, in step (3), the calcination refers to calcination at 1000 °C for 3 hours.

[0014] The third aspect of the present application provides a low-temperature proton ceramic fuel cell, which uses the above low-temperature proton ceramic fuel cell composite catalytic material as a cathode.

[0015] Further, the preparation method of the low-temperature proton ceramic fuel cell is as follows: an anode material composed of NiO, BZCYY and starch and electrolyte BZCYY powder are sequentially placed in a pressure mold, sintering is performed at a temperature of 1450 o C for 5 hours, a cathode material BCCF is coated on the surface of the electrolyte by screen printing, heat preservation is performed at 900 o C for 20 minutes, and a low-temperature proton ceramic fuel cell is obtained.

[0016] The fourth aspect of the present application provides application of the above composite catalytic material in a reversible proton ceramic battery.

[0017] Compared with the prior art, the present application has the following beneficial effects: The present application significantly improves the surface proton acid site concentration by doping Cs into BaCe 0.3 Fe 0.7 O 3-δ , optimizes the hydration ability and proton conduction performance, and realizes high-efficiency and stable operation of the proton ceramic fuel cell at low temperature. The material preparation process is simple, suitable for large-scale production, and has a broad application prospect. Specifically, the present application has the following advantages: (1) The power density of the composite catalytic material BCCF of the present application reaches 1.62 W cm -2 in a fuel cell mode at 700 °C, and the current density reaches -2.73 A cm -2 in an electrolysis mode at 650 °C (20% H2O).

[0018] (2) The Cs-doped composite catalytic material of the application can increase the proportion of surface proton acid sites (BAS) to 10.3%, reduce the oxygen vacancy formation energy (EVO=0.59 eV), improve the hydration capacity (Ehydration=-0.12 eV), and promote the generation and transmission of protons.

[0019] (3) The composite catalytic material of the application has no performance attenuation in a 100-hour long-term test in a 3% H2O environment, and the TEC is reduced to 16.16*10 -6 K -1 , and has good compatibility with electrolytes.

[0020] (4) The preparation method of the application adopts high-temperature calcination and sintering, and has the advantages of simple process, low cost and easy mass production. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is an XRD diagram of BCF and BCCF, wherein the left side is an XRD diagram of BCF, and the right side is an XRD diagram of BCCF.

[0022] Figure 2 It is a surface acidity site distribution analysis of BCF and BCCF by NH3-TPD and Py-IR, wherein a is a NH3 temperature programmed desorption analysis diagram of BCF and BCCF, b is a temperature programmed infrared spectrum analysis, c is a 500 o C in-situ shift test of H2O adsorption process (red) and purging process (blue) of BCF, and d is a 500 o C in-situ shift test of H2O adsorption process (red) and purging process (blue) of BCCF.

[0023] Figure 3 It is a schematic diagram of DFT calculation of oxygen vacancy formation energy and hydration energy of BCCF.

[0024] Figure 4 It is a performance and morphology diagram of fuel cell and electrolysis mode, wherein a is an alternating current impedance curve of a fuel cell with BCF and BCCF electrodes measured at 700 o C, b is a DRT analysis of the corresponding EIS data, c is the corresponding I-V and I-P curves of a, d is an EIS curve of a fuel cell with BCCF electrodes measured at 700 o C to 600 o C, e is a DRT analysis of the corresponding EIS data of d, f is an I-V and I-P curve of a fuel cell with BCCF electrodes measured at 700 o C to 600 o C, g is an I-V and I-P curve of a fuel cell with BCCF air electrodes measured at 600 oC is the operational stability test under constant current of 200 mA, h is the cross-sectional scanning electron microscope image of a single cell, and i is the schematic diagram of the fuel cell. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0027] Example 1: Preparation of BCCF powder Press Ba 0.95 Cs 0.05 Ce 0.3 Fe 0.7 O 3-δ Ba(NO3)2, CsNO3, Ce(NO3)3·6H2O, and Fe(NO3)3·9H2O were weighed out in stoichiometric ratio, dissolved in deionized water, and citric acid was added (metal ion:citric acid molar ratio = 1:1.5). The mixture was stirred at 80 °C until a gel was formed, and dried at 120 °C to obtain the precursor. The precursor was calcined at 1000 °C for 3 hours to obtain BCCF powder.

[0028] Comparative Example 1: Preparation of BCF Powder Press BaCe 0.3 Fe 0.7 O 3-δ Ba(NO3)2, Ce(NO3)3·6H2O, and Fe(NO3)3·9H2O were weighed out in stoichiometric ratio, dissolved in deionized water, and citric acid was added (metal ion:citric acid molar ratio = 1:1.5). The mixture was stirred at 80 °C until a gel was formed, and dried at 120 °C to obtain the precursor. The precursor was calcined at 1000 °C for 3 hours to obtain BCF powder.

[0029] Experimental Example 1: Material Characterization XRD analysis was performed on the BCCF powder in Example 1 and the BCF powder in Comparative Example 1. The XRD patterns of BCF and BCCF are shown below. Figure 1 As shown, the left side is the XRD pattern of BCF and the right side is the XRD pattern of BCCF. It can be seen that BCCF exhibits a biphase structure of cubic CP (69 wt%) and orthogonal OP (31 wt%). Cs doping causes the main peak (2θ=30.93°) to shift to the left to 30.64°.

[0030] The distribution of surface acid sites of BCF and BCCF analyzed by NH3-TPD and Py-IR is shown in FIG. 1, wherein a is the NH3 temperature programmed desorption analysis diagram of BCF and BCCF, b is the program temperature infrared spectrum analysis, c is the 500 Figure 2 o The in-situ shift test of BCF on H2O adsorption process (red) and purge process (blue) under 500 o The in-situ shift test of BCCF on H2O adsorption process (red) and purge process (blue) under 500

[0031] The schematic diagram of oxygen vacancy formation energy and hydration energy of BCCF analyzed by diffuse reflectance infrared spectroscopy DRIFT and DFT is shown in FIG. 2, which proves that the chemical adsorption capacity of BCCF on H2O is enhanced. Figure 3

[0032] The cell parameters of BCCF sample are shown in Table 1.

[0033] Table 1 As can be seen from Table 1, a = b = c = 4.132 Å (CP phase).

[0034] The content and binding energy of oxygen vacancies of BCF and BCCF are shown in Table 2.

[0035] Table 2 As can be seen from Table 2, the oxygen vacancy concentration O ads lat increased from 3.95 (BCF) to 5.5 (BCCF).

[0036] Example 2: Single cell assembly of cathode material BCCF 0.36 g of anode material composed of NiO, BZCYY and starch in a mass ratio of 6:4:2 and 0.006 g of electrolyte (BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ ) BZCYY powder were sequentially placed in a pressure mold, sintered at a temperature of 1350 o C for 5 h, and 0.36 g of cathode material (Ba 0.95 Cs 0.05 Ce 0.3 Fe 0.7 O 3-δ ​​​BZCYY powder 0.006 g were put into the pressure mold in turn, sintered at 1350 o C for 5 h, and a cathode material (BaCe -2 Fe -2 O 0.1 ) BCF was coated onto the surface of the electrolyte by screen printing, 900 0.7 C for 20 min to obtain a low-temperature proton ceramic fuel cell, the total area of the anode being 0.452 cm 0.1 , and the total area of the cathode being 0.19625 cm 0.1 .

[0037] The preparation method of the BZCYY powder is as follows: Ba(NO3)2, Ce(NO3)3·6H2O, Zr(NO3)4·5H2O, Y(NO3)3·6H2O, and Yb(NO3)3·5H2O are weighed according to the stoichiometric ratio of BaZr0.1Ce0.7Y0.1Yb0.1O3-δ, dissolved in deionized water, citric acid (molar ratio of metal ions to citric acid = 1:1.5) is added, ammonia water is used to adjust the pH value to about 8, stirring is carried out at 80 °C until a gel is formed, the precursor is dried at 120 °C, and the precursor is calcined at 1000 °C for 3 hours to obtain the BZCYY powder.

[0038] Comparative Example 2: Single cell assembly containing cathode material BCF Anode material 0.36 g composed of NiO, BZCYY, and starch in a mass ratio of 6:4:2 and electrolyte (BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ ) BZCYY powder 0.006 g were put into the pressure mold in turn, sintered at 1350 o C for 5 h, and a cathode material (BaCe 0.3 Fe 0.7 O 3-δ ) BCF was coated onto the surface of the electrolyte by screen printing, 900 o C for 20 min to obtain a low-temperature proton ceramic fuel cell, the total area of the anode being 0.452 cm -2 , and the total area of the cathode being 0.19625 cm -2 .

[0039] Experimental Example 2: Electrochemical performance test An electrochemical device, namely Squidstat Plus from Admiral Instruments, was used to evaluate the single cells in Example 2 and Comparative Example 2 using a four-probe setup. In fuel cell testing (FC), 3% H2O humidified H2 was delivered to the fuel electrode at a flow rate of 20 mL min -1 , while the air electrode received ambient air. In electrolysis testing (EC), the fuel electrode was exposed to H2 gas with 3% H2O. The air electrode received 20 mL min-1 Flow rate of air, which was also humidified with 3%, 10% and 20% H2O. The cell was stabilized at 700 o C, and then electrochemical tests were performed. Linear sweep voltammetry (LSV) was used to determine the current-voltage and current-power curves of the cell. In addition, electrochemical impedance spectroscopy (EIS) was tested when the circuit was open, using a frequency range of 0.1 o MHz and an AC amplitude of 10 mV. When performing relaxation time distribution (DRT) fitting, a Gaussian model was chosen to separate each frequency to characterize its response to time. The resulting performance and morphology of the fuel cell in electrolysis mode are shown in Figure 4 , where a is the AC impedance curve of the fuel cell with BCF and BCCF electrodes measured at 700 o C, b is the DRT analysis of the corresponding EIS data, c is the corresponding I-V and I-P curves of a, d is the EIS curve from 700 o C to 600 -1 C, e is the DRT analysis of the corresponding EIS data of d, f is the I-V and I-P curves of the fuel cell with BCCF electrodes from 700 o C to 600 o C, g is the running stability test of the fuel cell with BCCF air electrodes at 600 o C under a constant current of 200 mA, h is the cross-sectional scanning electron microscope image of the single cell, and i is the schematic diagram of the fuel cell. It can be seen that the fuel cell mode at 700 °C, with 3% H2O-H2 in the anode and air in the cathode, measured a BCCF power density of 1.62 W cm o -2.73 A cm o -2.73 A cm o -2.73 A cm -2 -2.73 A cm -2 -2.73 A cm

[0040] The above describes the embodiments of the present application in detail, but the present application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations of the embodiments can be made without departing from the principles and spirits of the present application, and still fall within the protection scope of the present application.

Claims

1. A low temperature protonic ceramic fuel cell composite catalytic material, characterized in that, The chemical formula of the composite catalytic material is Ba 0.95 Cs 0.05 Ce 0.3 Fe 0.7 O 3-δ , the composite catalytic material has a 69 wt% cubic and 31 wt% orthorhombic double perovskite structure.

2. The low temperature protonic ceramic fuel cell composite catalytic material of claim 1, wherein, The composite catalytic material has a thermal expansion coefficient of 16.16 x 10 o C is 16.16 x 10 -6 K -1 .

3. A method of producing a low temperature protonic ceramic fuel cell composite catalytic material as claimed in any one of claims 1-2, characterized in that, The preparation method comprises the following steps: (1) According to Ba 0.95 Cs 0.05 Ce 0.3 Fe 0.7 O 3-δ The stoichiometric ratio in the molecular formula refers to Ba(NO3)2, CsNO3, Ce(NO3)3.6H2O, Fe(NO3)3.9H2O, dissolved in deionized water; (2) adding citric acid, heating and stirring until a gel is formed, and drying to obtain a precursor; (3) calcining the precursor to obtain a low-temperature proton ceramic fuel cell composite catalytic material, namely BCCF powder.

4. The method of claim 3, wherein the method further comprises the step of: In step (2), the molar ratio of the citric acid to the metal ions is 1.5:

1. ​ 5. The method for preparing a low-temperature proton ceramic fuel cell composite catalyst according to claim 3, characterized in that, In step (2), the temperature of the heating is 80 o C.

6. The method for preparing a low-temperature proton ceramic fuel cell composite catalyst according to claim 3, characterized in that, In step (2), the temperature of the drying is 120 o C.

7. The method of claim 3, wherein the method further comprises the step of: In step (3), the calcining refers to calcining at 1000 °C for 3 hours. ​ 8. A low temperature proton ceramic fuel cell, characterized by, The low-temperature proton ceramic fuel cell adopts the low-temperature proton ceramic fuel cell composite catalytic material in any one of claims 1-2 as a cathode.

9. A cryogenic proton ceramic fuel cell according to claim 8, wherein, The preparation method of the low-temperature proton ceramic fuel cell comprises the following steps: sequentially placing an anode material composed of NiO, BZCYY and starch and an electrolyte BZCYY powder into a pressure mold, sintering at 1450 o C for 5 h, coating a cathode material BCCF on the surface of the electrolyte by screen printing, and keeping at 900 o C for 20 minutes to obtain the low-temperature proton ceramic fuel cell.

10. Application of the composite catalytic material in any one of claims 1-2 in a reversible proton ceramic battery.

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