Electrolyte of SOFC (solid oxide fuel cell) as well as preparation method and application of electrolyte

Abstract

The invention belongs to the technical field of fuel cells, and provides an electrolyte of an SOFC (solid oxide fuel cell) and a preparation method and application of the electrolyte. The preparation method comprises the following steps: mixing the oxide of the electrolyte matrix, the salt of the doping element, the sintering aid and the complexing agent to obtain mixed powder; and drying and calcining the mixed powder to obtain the catalyst. The invention also discloses the electrolyte of the SOFC prepared according to the method and the SOFC. The electrolyte comprises the electrolyte, a cathode, an anode and a connector. The sintering aid is added when the electrolyte of the SOFC is prepared, the mixed ceramic powder can be prepared through a one-step method, and the densification temperature of the electrolyte is reduced, so that the density of an electrolyte layer can be improved, and the battery performance of the SOFC can be further improved. The preparation process is simple, and electrolyte powder does not need to be prepared firstly and then a sintering aid does not need to be added.

Description

Technical Field

[0001] The present disclosure relates to the technical field of fuel cells, and in particular to an electrolyte of SOFC and a preparation method and application thereof. Background Art

[0002] Solid oxide fuel cell (SOFC) is a highly efficient energy conversion device that can directly convert chemical energy into electrical energy. The core components of SOFC include electrolyte, cathode (positive electrode), anode (negative electrode) and interconnect. The electrolyte plays a vital role in it. It not only conducts oxygen ions, but also separates the oxidant and fuel to prevent them from directly contacting and burning inside the battery.

[0003] The choice of electrolyte material has a significant impact on the performance of SOFC. At present, the more mature electrolyte materials include yttria-stabilized zirconia (YSZ), doped cerium oxide (such as Gd-doped cerium oxide, GDC), etc. These materials have the characteristics of high ionic conductivity, good chemical stability, mechanical strength, and matching the thermal expansion coefficient of the electrode material.

[0004] The most widely used cathode material is (La, Sr)(Co, Fe)O3 (LSCF), but it has poor chemical compatibility with the YSZ electrolyte, and a material with good chemical compatibility with both needs to be introduced as a barrier layer, such as GDC. However, the densification temperature of the GDC electrolyte is relatively high (≥1400°C). Too high a calcination temperature will cause a reaction between the two phases to form a low-conductivity phase, thereby reducing battery performance; while too low a calcination temperature will make the GDC layer less dense, resulting in a reduction in its ability to transport ions and Sr segregation, thereby reducing battery performance. Therefore, it is necessary to solve the problem of low-temperature densification of electrolyte films.

[0005] At present, there are technologies that improve the density of electrolytes by adding sintering aids, but these technologies have the following problems: the addition of sintering aids requires secondary addition after the preparation of electrolyte powder, which is a cumbersome process; there are few types of sintering aids, etc. Therefore, it is necessary to make some process improvements for these technologies. Summary of the invention

[0006] The present disclosure provides an electrolyte for SOFC and a preparation method and application thereof, so as to at least solve the above technical problems existing in the prior art.

[0007] According to a first aspect of the present disclosure, a method for preparing an electrolyte for a SOFC is provided, comprising the following steps:

[0008] S1: mixing the oxide of the electrolyte matrix, the salt of the doping element, the sintering aid and the complexing agent to obtain a mixed powder;

[0009] S2: Drying and calcining the mixed powder in step S1 to obtain the electrolyte of the SOFC.

[0010] In one embodiment, the oxide of the electrolyte matrix is ​​selected from at least one of zirconium oxide (ZrO2) and cerium oxide (CeO2).

[0011] In one embodiment, the salt of the doping element is selected from nitrates or acetates of the doping element.

[0012] In one embodiment, the doping element is selected from at least one of yttrium (Y), scandium (Sc), and rare earth elements.

[0013] Specifically, if the oxide of the electrolyte matrix is ​​ZrO2, the doping element is Y or Sc; if the oxide of the electrolyte matrix is ​​CeO2, the doping element is any one of rare earth elements and Y.

[0014] Specifically, the rare earth elements are lanthanide elements, including lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

[0015] In one embodiment, the sintering aid is selected from at least one of metal oxides or metal salts of Li, Bi, Mn, Fe, Co, Ni, Cu, Zn, and Mo.

[0016] Specifically, the metal salt is not particularly limited, such as carbonate, chloride, etc.

[0017] In one embodiment, the content of the sintering aid accounts for 0.01 to 5 mol% of the mixed powder.

[0018] In one embodiment, the complexing agent is selected from at least one of citric acid, ethylenediaminetetraacetic acid, and acrylic acid.

[0019] In one embodiment, the mass percentage of the complexing agent in the mixed powder is 1 to 50 wt %.

[0020] In one embodiment, in step S1, the oxide of the electrolyte matrix, the salt of the doping element, the sintering aid and the complexing agent are mixed by ball milling, and the ball milling time is 0.5 to 48 hours.

[0021] In one embodiment, the drying temperature in step S2 is 100-300°C.

[0022] In one embodiment, the calcination temperature in step S2 is 400-1400° C. and the calcination time is 1-20 h.

[0023] According to a second aspect of the present disclosure, there is provided an electrolyte for SOFC prepared according to the above preparation method.

[0024] According to a third aspect of the present disclosure, there is provided a SOFC comprising the above electrolyte, a cathode, an anode and a connector.

[0025] According to an implementable embodiment of the present disclosure, at least the following beneficial effects are achieved:

[0026] The present invention adds a sintering aid when preparing the electrolyte of SOFC, mixes the electrolyte parent oxide, the salt of the doping element and the sintering aid together, and prepares the mixed ceramic powder in a one-step method, which reduces the melting point of the electrolyte, that is, reduces the densification temperature of the electrolyte, thereby improving the density of the electrolyte layer, and further improving the battery performance of the solid oxide fuel cell. The preparation process of the present invention is simple, and there is no need to prepare the electrolyte powder first and then add the sintering aid.

[0027] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and other objects, features and advantages of the exemplary embodiments of the present disclosure will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present disclosure are shown in an exemplary and non-limiting manner, in which:

[0029] In the drawings, the same or corresponding reference numerals represent the same or corresponding parts.

[0030] Figure 1 The scanning electron microscopic observation image of the test sample prepared from the electrolyte powder of Comparative Example 1 of the present disclosure is shown;

[0031] Figure 2 shows a scanning electron microscopic observation image of a test sample prepared from the electrolyte powder of Example 2 of the present disclosure;

[0032] Figure 3 shows a scanning electron microscopic observation image of a test sample prepared from the electrolyte powder of Example 3 of the present disclosure;

[0033] Figure 4 The scanning electron micrograph of the test sample prepared from the electrolyte powder according to embodiment 5 of the present disclosure is shown. DETAILED DESCRIPTION

[0034] In order to make the purpose, features, and advantages of the present disclosure more obvious and easy to understand, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0035] Example 1

[0036] In this example, electrolyte Y for SOFC was prepared. 0.16 Zr 0.84 O2, the specific process is:

[0037] (1) Place zirconium oxide in a ball mill, add yttrium nitrate raw material and 1 mol% of sintering aid Li2CO3, then add 10 wt% of citric acid, and finally add an appropriate amount of deionized water, and ball mill for 10 hours to obtain a mixed powder.

[0038] (2) The mixed powder of step (1) was placed in an oven for drying, and the oven temperature was adjusted to 200° C.; and then calcined at 800° C. for 10 h to obtain electrolyte Y 0.16 Zr 0.84 O2.

[0039] Example 2

[0040] In this example, the electrolyte Gd for SOFC was prepared. 0.1 Ce 0.9 O2, the specific process is:

[0041] (1) Put cerium oxide into a ball mill, add gadolinium nitrate raw material and 3 mol% of sintering aid Co3O4, then add 20 wt% of ethylenediaminetetraacetic acid, and finally add an appropriate amount of deionized water, and ball mill for 24 hours to obtain a mixed powder.

[0042] (2) The mixed powder of step (1) was placed in an oven for drying, and the oven temperature was adjusted to 250°C; then calcined at 600°C for 20h to obtain electrolyte Gd 0.1 Ce 0.9 O2.

[0043] Example 3

[0044] In this example, the electrolyte Sm of SOFC was prepared. 0.2 Ce 0.8 O2, the specific process is:

[0045] (1) Put cerium oxide into a ball mill, add samarium nitrate raw material and 5 mol% of sintering aid NiO, then add 30 wt% of acrylic acid, and finally add an appropriate amount of deionized water, and ball mill for 48 hours to obtain a mixed powder.

[0046] (2) The mixed powder of step (1) is placed in an oven for drying, and the oven temperature is adjusted to 300° C.; and then calcined at 1000° C. for 2 h to obtain the electrolyte Sm 0.2 Ce 0.8 O2.

[0047] Example 4

[0048] In this example, the electrolyte Sc of SOFC was prepared. 0.2 Zr 0.8 O2, the specific process is:

[0049] (1) Place zirconium oxide in a ball mill, add scandium nitrate raw material and 3 mol% of sintering aid CuCl2, then add 5 wt% of citric acid, and finally add an appropriate amount of deionized water, and ball mill for 2 hours to obtain a mixed powder.

[0050] (2) The mixed powder of step (1) was placed in an oven for drying, and the oven temperature was adjusted to 220°C; then calcined at 1000°C for 2h to obtain electrolyte Sc 0.2 Zr 0.8 O2.

[0051] Example 5

[0052] In this example, the electrolyte La for SOFC was prepared. 0.4 Ce 0.6 O2, the specific process is:

[0053] (1) Place cerium oxide in a ball mill, add lanthanum nitrate raw material and 2 mol% sintering aid H 24 Mo7N6O 24 ·4H2O, then add 15wt% of ethylenediaminetetraacetic acid, and finally add appropriate amount of deionized water, and ball mill for 12h to obtain mixed powder.

[0054] (2) The mixed powder of step (1) was placed in an oven for drying, and the oven temperature was adjusted to 250°C; and then calcined at 400°C for 20h to obtain the electrolyte La 0.4 Ce 0.6 O2.

[0055] Comparative Example 1

[0056] In this comparative example, the electrolyte Gd for SOFC was prepared. 0.1 Ce 0.9 O2, the difference from Example 2 is that no sintering aid is added in this comparative example. The specific process is:

[0057] (1) Put cerium oxide into a ball mill, add gadolinium nitrate raw material, then add 20wt% ethylenediaminetetraacetic acid, and finally add an appropriate amount of deionized water, and ball mill for 24 hours to obtain a mixed powder.

[0058] (2) The mixed powder of step (1) was placed in an oven for drying, and the oven temperature was adjusted to 250°C; then calcined at 1300°C for 10 hours to obtain electrolyte Gd 0.1 Ce 0.9 O2.

[0059] Test example

[0060] First, an electrolyte layer YSZ was prepared, and then the electrolyte powders prepared in Examples 2, 3, 5 and Comparative Example 1 were pressed into thin film bodies on the surface of the electrolyte layer YSZ, and then calcined at 1300°C to obtain test samples. The microscopic morphology of each test sample was observed under a scanning electron microscope. The results are shown in FIG. Figure 1 to Figure 4 . Figure 1 It is shown that in the test sample prepared from the electrolyte powder of Comparative Example 1, the density of the GDC layer after calcination is relatively low. This is because no sintering aid was added when preparing the GDC electrolyte powder in Comparative Example 1, that is, it was pure GDC electrolyte powder. The densification temperature of pure GDC electrolyte is relatively high (≥1400°C), and calcination at 1300°C did not reach its densification temperature. Therefore, low densification of the GDC layer can be observed. When preparing the electrolyte powder in Examples 2, 3, and 5, sintering aids were added to reduce the melting point of the electrolyte, that is, reduce the densification temperature of the electrolyte. Therefore, Figure 2 , Figure 3 , Figure 4 It can be observed that the GDC layer, SDC layer and LDC layer in the test samples corresponding to the electrolyte powders of Examples 2, 3 and 5 have a high degree of densification after calcination at 1300°C.

[0061] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of this disclosure can be achieved, and this document is not limited here.

[0062] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0063] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for preparing an electrolyte for SOFC, characterized in that: The following steps are involved: S1: mixing the oxide of the electrolyte matrix, the salt of the doping element, the sintering aid and the complexing agent to obtain a mixed powder; S2: Drying and calcining the mixed powder in step S1 to obtain the electrolyte of the SOFC.

2. The preparation method according to claim 1, characterized in that: The oxide of the electrolyte matrix is ​​selected from at least one of zirconium oxide and cerium oxide.

3. The preparation method according to claim 1, characterized in that: The salt of the doping element is selected from the nitrate or acetate of the doping element; Preferably, the doping element is selected from at least one of yttrium, scandium and rare earth elements; Preferably, the rare earth element is a lanthanide element, including lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

4. The preparation method according to claim 1, characterized in that: The sintering aid is selected from at least one of metal oxides or metal salts of Li, Bi, Mn, Fe, Co, Ni, Cu, Zn, and Mo; Preferably, the content of the sintering aid accounts for 0.01 to 5 mol% of the mixed powder.

5. The preparation method according to claim 1, characterized in that: The complexing agent is selected from at least one of citric acid, ethylenediaminetetraacetic acid, and acrylic acid; Preferably, the mass percentage of the complexing agent in the mixed powder is 1 to 50 wt %.

6. The preparation method according to claim 1, characterized in that: Step S1: mixing the oxide of the electrolyte matrix, the salt of the doping element, the sintering aid and the complexing agent by ball milling, wherein the ball milling time is 0.5 to 48 hours.

7. The preparation method according to claim 1, characterized in that: The drying temperature in step S2 is 100-300°C.

8. The preparation method according to claim 1, characterized in that: The calcination temperature in step S2 is 400-1400° C. and the calcination time is 1-20 hours.

9. An electrolyte for SOFC prepared according to the preparation method according to any one of claims 1 to 8.

10. A SOFC, characterized in that: The SOFC comprises the electrolyte of claim 9, a cathode, an anode and an interconnector.

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