A novel layered perovskite-like structure solid-state electrolyte material, a preparation method and application thereof

Abstract

This invention provides a novel layered perovskite-like solid electrolyte material, its preparation method, and its applications, belonging to the field of solid oxide fuel cell technology. The solid electrolyte material, as an oxygen ion conductor, has the general chemical formula Cs(Bi) 3₋x Sr x Ti4O 13₋δ , where 0≤ x ≤0.5; obtained by mixing and grinding the raw materials with an organic solvent, pressing the dried material into sheets, and then calcining it in a muffle furnace. This invention is the first to apply a four-layer Dion-Jacobson phase material as an oxygen ion conductor to a solid oxide fuel cell. By introducing oxygen vacancies through divalent ion doping, its ionic conductivity is significantly improved, and the abrupt change in the parent phase conductivity is eliminated. The bulk conductivity reaches 4.3 × 10⁻⁻⁻⁻⁶ at 800℃. 2 The ionic conductivity of the material is approximately 60 times higher than that of the parent phase material at 600℃ (S cm⁻¹). The material prepared in this invention has a simple process, and the ionic conductivity at operating temperature is effectively improved through metal doping, making it a promising candidate for application in mid-temperature solid oxide fuel cells.

Description

Technical Field

[0001] This invention belongs to the field of solid oxide fuel cell technology, and particularly relates to a novel layered perovskite-like solid electrolyte material, its preparation method and application. Background Technology

[0002] Solid oxide fuel cells (SOFCs), as energy conversion devices that directly convert chemical energy into electrical energy, have attracted widespread attention due to their high energy conversion efficiency, wide range of fuel applicability, and environmental friendliness. The core component of a SOFC is the solid electrolyte, whose ionic conductivity directly determines the cell's performance. Currently, widely used solid electrolyte materials mainly include fluorite-type yttrium-stabilized zirconium oxide (YSZ) and perovskite-type lanthanum gallate-based materials (such as LSGM). However, these traditional electrolyte materials typically require high operating temperatures (800-1000 °C). Prolonged operation at such high temperatures can lead to side reactions between cell components, damage to electrode microstructures due to sintering, difficulties in cell encapsulation, and limitations in material selection. Lowering the operating temperature of SOFCs to the mid-temperature range (500-800 °C) is an effective way to promote their practical application, but lowering the operating temperature also leads to a significant decrease in electrolyte ionic conductivity, thus affecting the cell's output performance. How to reduce the operating temperature while ensuring SOFC performance remains a current research challenge.

[0003] Current research on traditional fluorite and perovskite solid electrolyte materials has reached a high level, but their highly symmetrical three-dimensional crystal structure and single oxygen vacancy conduction mechanism limit their further development. However, at medium and low temperatures, some novel structures can maintain asymmetric, relatively distorted cell structures and easily form interstitial oxygen or oxygen vacancies and other oxygen defect sites in the lattice. The crystallographic characteristics of these materials provide possibilities for oxygen ion conduction at medium and low temperatures. Therefore, novel structures hold promise for improving the oxygen ion conductivity of SOFC solid electrolytes under medium and low temperature conditions. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a novel layered perovskite-like solid electrolyte material, its preparation method, and its applications. The solid electrolyte material comprises CsBi3Ti4O with a Dion-Jacobson phase. 13 Or use it as the mother phase to perform Sr 2+ By introducing oxygen vacancies through doping, solid electrolyte materials can act as oxygen ion conductors, significantly improving oxygen ion conductivity. Moreover, the preparation method is simple, reproducible, and the prepared materials have stable properties, making them suitable as high-quality electrolytes for electrochemical devices such as solid oxide fuel cells.

[0005] The technical solution of the present invention is as follows: A novel layered perovskite-like solid electrolyte material is proposed, which has a four-layer Dion-Jacobson phase structure and an orthorhombic crystal system. P twenty one am Space group, chemical formula Cs(Bi) 3-x Sr x Ti4O 13-δ , where 0 ≤ x ≤ 0.5, δ=x / 2 represents the number of oxygen vacancies generated by charge balance; the solid electrolyte material serves as an oxygen ion conductor.

[0006] Preferred value 0.1≤ x ≤ 0.5; further, 0.15 ≤ x ≤ 0.5, and further, 0.15 ≤ x ≤ 0.25.

[0007] This invention also provides a method for preparing a novel layered perovskite-like solid electrolyte material, comprising the following steps: (1) Place the cesium source, bismuth source, titanium source and organic solvent in a mortar, or place the cesium source, bismuth source, titanium source, strontium source and organic solvent in a mortar, mix them evenly until dry, and press them into electrolyte sheets; (2) The electrolyte sheet was transferred to a muffle furnace for calcination to obtain a high-temperature ceramicized solid electrolyte material; (3) After cooling, take out the material, grind it into powder, repeat the pressing in step (1) and step (2) to synthesize a pure phase novel layered perovskite-like solid electrolyte material.

[0008] In step (1), the molar ratio of cesium in the cesium source to titanium in the titanium source is 1.3~1.5:4, with cesium added in excess to compensate for the volatilization loss of the cesium component during sintering. The grinding time is 0.5~1 h.

[0009] The cesium source is cesium carbonate, the bismuth source is bismuth oxide, the titanium source is titanium dioxide, and the strontium source is strontium carbonate. The organic solvent is anhydrous ethanol.

[0010] In step (1), an electrolyte tablet is formed using a uniaxial tablet press and a mold. The pressure of the uniaxial tablet press is 200~300MPa.

[0011] In step (2), the calcination temperature is 700~900 ℃, the calcination time is 12~24 h, and the heating rate is 5 ℃ / min.

[0012] The present invention also provides the application of the novel layered perovskite-like solid electrolyte material in solid oxide fuel cells.

[0013] Compared with existing technologies, the advantages of this invention are as follows: 1. This invention is the first to utilize the Dion-Jacobson structure material CsBi3Ti4O 13 As an oxygen ion conductor, at 10 -33 The constant conductivity over a wide oxygen partial pressure range of ~1 atm proves that it is oxygen ion-dominated and can be used in SOFC electrolytes. Based on this, an Sr-doped oxygen ion conductor was prepared for the first time. Oxygen vacancies were introduced through a charge compensation mechanism to increase the carrier concentration and eliminate the parent phase CsBi3Ti4O 13 To address the abrupt change in conductivity near 600 °C, a steady increase in conductivity with temperature was achieved. At 600 °C, the conductivity was approximately 60 times higher than that of the parent phase, and at 800 °C, the bulk conductivity reached 4.3 × 10⁻⁶. -2 S cm -1 It exhibits excellent electrical conductivity, reaching a commercially viable level.

[0014] 2. This invention uses a solid-state reaction method for preparation, which is simple, convenient to operate, uses readily available raw materials, and has low cost. Furthermore, the purity and density of the product are ensured through multiple grinding and sintering processes, resulting in good repeatability and suitability for large-scale industrial production. Moreover, it exhibits no phase decomposition at 800 °C and excellent chemical and thermal stability, meeting the actual operating requirements of electrochemical devices. Attached Figure Description

[0015] Figure 1 Cs(Bi) prepared in Examples 1-6 3-x Sr x Ti4O 13-δ XRD patterns of (x=0, 0.1, 0.2, 0.3, 0.4, 0.5).

[0016] Figure 2 Cs(Bi) prepared in Examples 1-6 3-x Sr x Ti4O 13-δ DC conductivity (x=0, 0.1, 0.2, 0.3, 0.4, 0.5).

[0017] Figure 3 Example 1: CsBi3Ti4O 13 and Example 3 CsBi 2.8 Sr 0.2 Ti4O 12.9 Total ionic conductivity.

[0018] Figure 4 CsBi prepared for Comparative Examples 1-2 3-x Ba x Ti4O 13-δ ( xDC conductivity (= 0.2, 0.3).

[0019] Figure 5 Example 1: CsBi3Ti4O 13 DC conductivity under different oxygen partial pressures.

[0020] Figure 6 Example 3 CsBi 2.8 Sr 0.2 Ti4O 12.9 Electrical conductivity in dry and humid air.

[0021] Figure 7 Example 3 CsBi 2.8 Sr 0.2 Ti4O 12.9 TG curves from room temperature to 800 °C in dry air. Detailed Implementation

[0022] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments. They do not constitute a limitation on the content and scope of protection of the present invention. Any modifications or refinements made to the subject matter and spirit of the present invention that are not of substantial significance, but solve the same technical problem as the present invention, should be included within the scope of protection of the present invention.

[0023] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0024] Example 1 This embodiment provides a novel layered perovskite-like solid electrolyte material and its preparation method, the specific steps of which are as follows: Step 1: According to the chemical formula CsBi3Ti4O 13 According to the stoichiometric ratio, weigh 1.054 g of cesium carbonate, 3.014 g of bismuth oxide, and 1.378 g of titanium dioxide. Place the above raw materials in an agate mortar, add 10 mL of anhydrous ethanol as a dispersant, and grind thoroughly for 30 min until the slurry is uniform and free of obvious particles. Place the slurry in a 60℃ oven and dry to constant weight to obtain a mixed powder.

[0025] Step 2: Place the dried mixed powder in a circular mold and uniaxially press it into a disc under a pressure of 200 MPa; place the disc in a muffle furnace and press it in static air at 5 K min. -1 The temperature was increased to 800 °C at a rate of [missing value], held for 12 h, and then increased at 5 K min [missing value]. -1The sample was cooled to room temperature at a certain rate to obtain a pre-calcined sample.

[0026] Step 3: Crush the initial calcined sample into powder, place it in an agate mortar and grind it into a fine powder. Repeat the above pressing steps, and then sinter it in a muffle furnace at the same heating and cooling rates and temperature for 12 h to obtain pure phase CsBi3Ti4O. 13 Oxygen ion conductor.

[0027] Examples 2-6 This embodiment provides a novel layered perovskite-like solid electrolyte material and its preparation method, the specific steps of which are as follows: Step 1: According to the chemical formula Cs(Bi) 3-x Sr x Ti4O 13-δ ( x Weigh out cesium carbonate, bismuth oxide, strontium carbonate, and titanium dioxide in a stoichiometric ratio of 0.1, 0.2, 0.3, 0.4, and 0.5, with cesium carbonate in 50% mol excess. Place the above raw materials in an agate mortar, add 10 mL of anhydrous ethanol as a dispersant, and grind thoroughly for 30 min until the slurry is uniform and free of obvious particles. Place the slurry in a 60℃ oven and dry to constant weight to obtain a mixed powder.

[0028] Step 2: Place the dried mixed powder in a circular mold and uniaxially press it into a disc under a pressure of 200 MPa; place the disc in a muffle furnace and press it in static air at 5 K min. -1 The temperature was increased to 800 °C at a rate of [missing value], held for 12 h, and then increased at 5 K min [missing value]. -1 The sample was cooled to room temperature at a certain rate to obtain a pre-calcined sample.

[0029] Step 3: Crush the initial calcined sample into powder, place it in an agate mortar and grind it into a fine powder. Repeat the above tableting steps, and then sinter it in a muffle furnace at the same heating and cooling rates and temperature for 12 hours to obtain pure Cs(Bi). 3-x Sr x Ti4O 13-δ ( x =0.1, 0.2, 0.3, 0.4, 0.5) oxygen ion conductors.

[0030] Comparative Examples 1-2 This embodiment provides a novel layered perovskite-like solid electrolyte material and its preparation method, the specific steps of which are as follows: Step 1: According to the chemical formula CsBi 3-x Ba x Ti4O 13-δ ( xWeigh out cesium carbonate, bismuth oxide, barium carbonate, and titanium dioxide in a stoichiometric ratio of 0.2, 0.3, with cesium carbonate in 50% mol excess. Place the above raw materials in an agate mortar, add 10 mL of anhydrous ethanol as a dispersant, and grind thoroughly for 30 min until the slurry is uniform and free of obvious particles. Place the slurry in a 60℃ oven and dry to constant weight to obtain a mixed powder.

[0031] Step 2: Place the dried mixed powder in a circular mold and press it into a disc under a uniaxial pressure of 200 MPa; place the disc in a muffle furnace and heat it to 800 °C at a rate of 5 K min⁻¹ in static air, hold it at that temperature for 12 h, and then cool it to room temperature at a rate of 5 K min⁻¹ to obtain the initial calcined sample.

[0032] Step 3: Crush the initial calcined sample into powder, grind it into a fine powder in an agate mortar, repeat the tableting steps above, and then sinter it in a muffle furnace at the same heating and cooling rates and temperature for 12 hours to obtain pure CsBi. 3-x Sr x Ti4O 13-δ ( x = 0.2, 0.3) Oxygen ion conductor.

[0033] The results show that: (1) as Figure 1 As shown in the XRD patterns, all diffraction peaks of the series of electrolyte materials prepared can be indexed to an orthorhombic crystal system. P twenty one am The space group is empty, indicating that the product is a pure-phase four-layer Dion-Jacobson structure, and the synthesis was successful; (2) Figure 2 The conductivity results are shown in the range of 350~800 °C. The conductivity at 800 °C is shown in Table 1. For all materials, CsBi... 2.8 Sr 0.2 Ti4O 12.9 It exhibits the best electrical conductivity, with a bulk conductivity of 4.3 × 10⁻⁶ at 800 °C after fitting. -2 S cm -1 (3) As the Sr doping ratio increases, the abrupt change in conductivity between 550 and 650 °C gradually disappears. x = 0.2 yields the best results, such as Figure 3 As shown, the conductivity was improved while eliminating the sudden change. Within the test temperature range, the conductivity was improved by 1 to 2 orders of magnitude; (4) Sr was doped with Ba, a main group element, such as Figure 4 As shown, although the sudden change phenomenon was alleviated to some extent, it could not be completely eliminated, and the conductivity decreased significantly compared with the parent phase, indicating poor doping effect; (5) Figure 5 In the middle, CsBi3Ti4O 13 In 10 -33Its conductivity remains constant over a wide oxygen partial pressure range of ~1 atm, proving that it is an oxygen ion conductor; (6) such as Figure 6 As shown, within the temperature range of 500–800 °C, there was no significant difference in the conductivity of the samples in humid and dry air, indicating that CsBi 2.8 Sr 0.2 Ti4O 12.9 It exhibits no significant proton conductivity and is an oxygen ion conductor. (7) From Figure 7 It can be seen that, within the range of room temperature to 800 ℃, CsBi 2.8 Sr 0.2 Ti4O 12.9 The fact that the material did not decompose or volatilize indicates that it has good high-temperature stability.

[0034] Table 1. Parameters and performance of each embodiment and comparative example. Electrolyte materials Doping elements Doping ratio Sintering temperature Sintering time <![CDATA[DC conductivity / S cm -1 > Example 1 / / 800 ℃ 12+12 h <![CDATA[2.73×10 -3 ]]> Example 2 Sr 0.1 800 ℃ 12+12 h <![CDATA[5.25×10 -4 ]]> Example 3 Sr 0.2 800 ℃ 12+12 h <![CDATA[4.82×10 -3 ]]> Example 4 Sr 0.3 800 ℃ 12+12 h <![CDATA[5.07×10 -4 ]]> Example 5 Sr 0.4 800 ℃ 12+12 h <![CDATA[8.84×10 -4 ]]> Example 6 Sr 0.5 800 ℃ 12+12 h <![CDATA[3.17×10 -4 ]]> Comparative Example 1 Ba 0.2 800 ℃ 12+12 h <![CDATA[8.74×10 -4 ]]> Comparative Example 2 Ba 0.3 800 ℃ 12+12 h <![CDATA[3.64×10 -4 ]]> The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A novel layered perovskite-like solid electrolyte material, characterized in that: It has a four-layer Dion-Jacobson phase structure and an orthorhombic crystal system. P twenty one am Space group, chemical formula Cs(Bi) 3-x Sr x Ti4O 13-δ , where 0 ≤ x ≤0.5, δ=x / 2 represents the number of oxygen vacancies generated by charge balance; the solid electrolyte material serves as an oxygen ion conductor.

2. The novel layered perovskite-like solid electrolyte material as described in claim 1, characterized in that: 0.1≤ x ≤ 0.5。 3. The novel layered perovskite-like solid electrolyte material as described in claim 2, characterized in that: 0.15≤ x ≤ 0.5。 4. The novel layered perovskite-like solid electrolyte material as described in claim 3, characterized in that: 0.15≤ x ≤ 0.25。 5. A method for preparing the novel layered perovskite-like solid electrolyte material according to claim 1, characterized in that: Includes the following steps: Place the cesium source, bismuth source, titanium source and organic solvent in a mortar, or place the cesium source, bismuth source, titanium source, strontium source and organic solvent in a mortar, mix evenly until dry, and press into an electrolyte sheet; The electrolyte sheet was transferred to a muffle furnace for calcination to obtain a high-temperature ceramicized solid electrolyte material. After cooling, the material is taken out and ground into powder. The pressing in step (1) and step (2) are repeated to synthesize a pure phase novel layered perovskite-like solid electrolyte material.

6. The method for preparing the novel layered perovskite-like solid electrolyte material as described in claim 5, characterized in that: In step (1), the molar ratio of cesium in the cesium source to titanium in the titanium source is 1.3~1.5:4; the grinding time is 0.5~1h.

7. The method for preparing the novel layered perovskite-like solid electrolyte material as described in claim 5, characterized in that: The cesium source is cesium carbonate, the bismuth source is bismuth oxide, the titanium source is titanium dioxide, the strontium source is strontium carbonate, and the organic solvent is anhydrous ethanol.

8. The method for preparing the novel layered perovskite-like solid electrolyte material as described in claim 5, characterized in that: In step (1), an electrolyte tablet is formed using a uniaxial tablet press and a mold. The pressure of the uniaxial tablet press is 200~300 MPa.

9. The method for preparing the novel layered perovskite-like solid electrolyte material as described in claim 5, characterized in that: In step (2), the calcination temperature is 700~900 ℃ and the calcination time is 12~24 h.

10. The application of the novel layered perovskite-like solid electrolyte material of claim 1 in a solid oxide fuel cell.

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