CN115241471B - Cathode material of solid oxide fuel cell and preparation method and application thereof - Google Patents

Abstract

The invention discloses a solid oxide fuel cell cathode material, the chemical formula of which is Sr ₄Fe_xCo_yO_13+δ, wherein 0< x <4, 2< y <6, δ is oxygen vacancy concentration, and 0< δ <1. The invention also discloses a preparation method of the solid oxide fuel cell cathode material, which comprises the following steps: weighing strontium nitrate, ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ethylenediamine tetraacetic acid, citric acid monohydrate and ammonia water; sequentially dissolving in deionized water, heating and stirring to gel; drying to obtain a precursor; removing carbon from the precursor, and calcining the precursor under partial pressure of oxygen to obtain powder; grinding the powder to obtain Sr ₄Fe_xCo_yO_13+δ cathode material powder. The invention also discloses application of the catalyst in low-temperature oxygen ion conductor-based solid oxide fuel cells and low-temperature proton ceramic fuel cells. The solid oxide fuel cell cathode material prepared by the invention has excellent cell output performance.

Description

A solid oxide fuel cell cathode material and its preparation method and application

Technical Field

The present invention relates to cathode materials and a preparation method and application thereof, and in particular to a solid oxide fuel cell cathode material and a preparation method and application thereof.

Background Art

Solid oxide fuel cells (SOFCs) have become the leaders in the development of clean energy with their high efficiency, pollution-free and environmentally friendly features. They are considered to be one of the most promising energy conversion devices and are of great significance in alleviating energy crises and environmental pollution. Although SOFCs exhibit ideal electrochemical performance at higher operating temperatures, excessively high temperatures also bring many problems, such as high sealing costs, electrode material sintering, and thermal expansion mismatch, which affect the service life of the battery. Therefore, lowering the operating temperature is the development trend of SOFCs.

As the operating temperature decreases, especially at operating temperatures below 600°C, the polarization impedance of the cathode material increases sharply and the catalytic activity decreases significantly, affecting the output power of SOFC, thereby limiting the practical application of SOFC. Therefore, the development of cathode materials for solid oxide fuel cells with high oxygen reduction activity and long-term stability at operating temperatures below 600°C has become a research hotspot.

Summary of the invention

Purpose of the invention: In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a long-term, efficient and stable solid oxide fuel cell cathode material. Another purpose of the present invention is to provide a simple, efficient and low-cost method for preparing a solid oxide fuel cell cathode material. Another purpose of the present invention is to provide an application of a solid oxide fuel cell cathode material in a low-temperature oxygen ion conductor-based solid oxide fuel cell. Another purpose of the present invention is to provide an application of a solid oxide fuel cell cathode material in a low-temperature proton ceramic fuel cell.

Technical solution: The solid oxide fuel cell cathode material of the present invention has a chemical formula of Sr ₄ Fe _x Co _y O _13+δ (SFC4), wherein 0<x<4, 2<y<6, δ is the oxygen vacancy concentration, and 0<δ<1.

Furthermore, the average particle size of the cathode material is 300-500 nm.

The method for preparing the solid oxide fuel cell cathode material comprises the following steps:

Step 1, weighing strontium nitrate, ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ethylenediaminetetraacetic acid, citric acid monohydrate and ammonia water respectively according to the stoichiometric ratio;

Step 2, dissolving the above raw materials in deionized water in sequence, and heating and stirring until they are in a gel state;

Step 3, drying the product obtained in step 2 in an oven to obtain a precursor;

Step 4, placing the precursor obtained in step 3 in a muffle furnace for decarbonization, and then calcining under oxygen partial pressure to obtain a powder;

Step 5: Grind the powder obtained in step 4 to obtain Sr ₄ Fe _x Co _y O _13+δ cathode material powder.

Furthermore, in step 1, the molar ratio of ethylenediaminetetraacetic acid: citric acid monohydrate: metal cation is 1:2:1-2, and the molar number of the metal cation is the sum of the molar numbers of strontium nitrate, ferric nitrate nonahydrate, and cobalt nitrate hexahydrate.

Furthermore, in step 2, strontium nitrate, ferric nitrate nonahydrate, and cobalt nitrate hexahydrate are first dissolved in deionized water, heated and stirred to obtain a metal nitrate solution, and then ethylenediaminetetraacetic acid is dissolved in ammonia water, and ammonia water and citric acid monohydrate dissolved in ethylenediaminetetraacetic acid are added to the metal nitrate solution, and heating and stirring are continued until it is in a gel state. The heating temperature is 80-100°C, and the stirring speed is 200-300r·min ^-1 . If the heating temperature is lower than 80°C, the gel formation rate will be slowed down; if the heating temperature is higher than 100°C, the stirring time will be shortened, and the gel will easily foam at high temperature. If the stirring speed is lower than 200r·min ^-1 , the uniformity of the complexation of metal ions will be affected; if the stirring speed is higher than 300r·min ^-1 , the solution will splash.

Furthermore, in step 3, the drying temperature is 200-300°C and the time is 200-300 minutes. A drying temperature lower than 200°C will result in insufficient carbonization of organic matter in the gel; a drying temperature higher than 300°C will result in combustion of the carbon skeleton.

Furthermore, in step five, the powder is sieved with a 200-400 mesh sieve after grinding.

The solid oxide fuel cell cathode material is used in a low-temperature oxygen ion conductor-based solid oxide fuel cell, using Sr ₄ Fe _x Co _y O _13+δ as the cathode, samarium oxide-doped cerium oxide as the electrolyte, and a mixture of NiO and SDC as the anode.

The solid oxide fuel cell cathode material is used in a low-temperature proton ceramic fuel cell, with Sr ₄ Fe _x Co _y O _13+δ as the cathode, BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ as the electrolyte, and a mixture of NiO and BZCYYb as the anode.

Preparation principle: Sr ₄ Fe _x Co _y O _13+δ material is composed of nano-scale single perovskite phase Sr(Co,Fe)O ₃ , spinel phase (Co,Fe) ₃ O ₄ , cobalt oxide CoO and strontium carbonate SrCO _3. The single perovskite phase, spinel phase and self-assembly mixture with strontium carbonate and cobalt oxide, among which the single perovskite phase has excellent conductivity and good oxygen reduction activity, the spinel phase has low conductivity but high oxygen reduction catalytic activity, and the presence of strontium carbonate and cobalt oxide reduces the thermal expansion coefficient, ensuring long-term operational stability. Through the self-assembly mixing of the nano-scale catalysts of the above system and the influence of the synergistic effect, the battery prepared by the material can have excellent output power and long-term stability, and the structure is stable in the low temperature range. It can show good ORR catalytic activity when applied to O-SOFC and PCFC.

Beneficial effects: Compared with the prior art, the present invention has the following significant features:

1. The prepared solid oxide fuel cell cathode material has excellent battery output performance. The output power of the prepared low-temperature proton ceramic fuel cell at 550°C reaches 645mW·cm ^-2 , and the output power of the prepared oxygen ion conductor-based fuel cell at 600°C reaches 1250mW·cm ^-2 ;

2. The prepared solid oxide fuel cell cathode material has excellent long-term thermochemical stability. The proton-based symmetric battery and proton ceramic fuel cell can work continuously for 1000 hours and 3100 hours at 550°C respectively, and their impedance and output power have no obvious attenuation. The prepared oxygen ion-based symmetric battery can work continuously for 1000 hours at 550°C, and its impedance has no obvious attenuation, which shows good thermal stability.

3. The prepared cathode material has a wide range of applications and has certain proton conductivity properties. Therefore, the material can be used not only as an O-SOFC cathode, but also as a PCFC cathode.

4. The cathode material is synthesized by a simple sol-gel one-step method. The preparation method is simple and efficient, the raw material cost is low, and it is suitable for industrial large-scale production;

5. The average particle size of the cathode material SFC4 is at the nanoscale, which increases the effective three-phase line length inside the structure, thus having a larger electrochemical reaction range;

6. Use oxygen partial pressure calcination, that is, in a closed environment, oxygen gradually decreases with calcination, and carbonates can be generated, so that the cathode material can maintain stable operation for a long time;

7. When the cathode material SFC4 is prepared, a layered perovskite phase will be generated. This structure has good chemical flexibility, high electrical conductivity and strong structural stability, so that the cathode material can maintain stable operation for a long time.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an XRD diagram of the SFC4 cathode material of the present invention;

FIG2 is an impedance diagram of the oxygen ion-based symmetrical battery SFC4|SDC|SFC4 of the present invention at 550° C.;

FIG3 is a long-term stability diagram of the oxygen ion-based symmetrical battery SFC4|SDC|SFC4 of the present invention at 550° C.;

4 is a power output performance diagram of the oxygen ion-based fuel cell SFC4|SDC|NiO-SDC of the present invention at temperatures of 400° C., 500° C. and 600° C.;

5 is a SEM image of a cross section of an oxygen ion-based fuel cell SFC4|SDC|NiO-SDC of the present invention;

FIG6 is an impedance diagram of the proton-based symmetric battery SFC4|BZCYYb|SFC4 of the present invention at 550° C.;

FIG7 is a long-term stability diagram of the proton-based symmetric battery SFC4|BZCYYb|SFC4 of the present invention at 550° C.;

8 is a graph showing the power output performance of the proton ceramic fuel cell SFC4|BZCYYb|NiO-BZCYYb of the present invention at temperatures of 350° C., 450° C. and 550° C.;

9 is a SEM image of a cross section of a proton ceramic fuel cell SFC4|BZCYYb|NiO-BZCYYb of the present invention;

FIG. 10 is a graph showing the long-term stability of the proton ceramic fuel cell SFC4|BZCYYb|NiO-BZCYYb of the present invention at 550° C.

DETAILED DESCRIPTION

In the following examples, the carbon removal treatment is to place the precursor in a muffle furnace and calcine it at 700° C. for 5 hours. The molar number of the metal cation is the sum of the molar numbers of strontium nitrate, ferric nitrate nonahydrate, and cobalt nitrate hexahydrate.

Example 1

A method for preparing a cathode material for a solid oxide fuel cell comprises the following steps:

a. According to the stoichiometric ratio, weigh strontium nitrate, ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ethylenediaminetetraacetic acid, citric acid monohydrate and ammonia water respectively, and the molar ratio of ethylenediaminetetraacetic acid: citric acid monohydrate: metal cation is 1:2:1;

b. First, strontium nitrate, ferric nitrate nonahydrate and cobalt nitrate hexahydrate are dissolved in deionized water, and heated and stirred at a temperature of 80°C and a rotation speed of 300 r·min ^-1 to obtain a metal nitrate solution. At the same time, deionized water and ammonia water are added to ethylenediaminetetraacetic acid, and ammonia water and citric acid monohydrate dissolved in ethylenediaminetetraacetic acid are added to the metal nitrate solution, and the temperature is continued to be 80°C and the rotation speed is 300 r·min ^-1 . Stirring until the solution becomes a gel;

c. drying the gel obtained in step b in an oven at 200° C. for 300 min to obtain a precursor;

d. placing the precursor obtained in step c in a muffle furnace for carbon removal, and then calcining under oxygen partial pressure to obtain a powder;

e. Grind the powder obtained in step 4, and sieve it with a 200-mesh sieve to obtain Sr ₄ Fe _0.5 Co _5.5 O _13+δ (SFC4) cathode material powder with an average particle size of 300 nm.

Example 2

A method for preparing a cathode material for a solid oxide fuel cell comprises the following steps:

a. According to the stoichiometric ratio, weigh strontium nitrate, ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ethylenediaminetetraacetic acid, citric acid monohydrate and ammonia water respectively, and the molar ratio of ethylenediaminetetraacetic acid: citric acid monohydrate: metal cation is 1:2:2;

b. First, strontium nitrate, ferric nitrate nonahydrate and cobalt nitrate hexahydrate are dissolved in deionized water, and heated and stirred at a temperature of 100°C and a rotation speed of 200 r·min ^-1 to obtain a metal nitrate solution. At the same time, deionized water and ammonia water are added to ethylenediaminetetraacetic acid, and ammonia water and citric acid monohydrate dissolved in ethylenediaminetetraacetic acid are added to the metal nitrate solution, and the temperature is continued to be 100°C and the rotation speed is 200 r·min ^-1 . Stirring until the solution becomes a gel;

c. drying the gel obtained in step b in an oven at 300° C. for 200 min to obtain a precursor;

d. placing the precursor obtained in step c in a muffle furnace for carbon removal, and then calcining under oxygen partial pressure to obtain a powder;

e. Grind the powder obtained in step 4, and sieve it with a 400-mesh sieve to obtain Sr ₄ Fe _3.5 Co _2.5 O _13+δ (SFC4) cathode material powder with an average particle size of 500 nm.

Example 3

A method for preparing a cathode material for a solid oxide fuel cell comprises the following steps:

a. According to the stoichiometric ratio, weigh strontium nitrate, ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ethylenediaminetetraacetic acid, citric acid monohydrate and ammonia water respectively, and the molar ratio of ethylenediaminetetraacetic acid: citric acid monohydrate: metal cation is 1:2:1.5;

b. First, strontium nitrate, ferric nitrate nonahydrate and cobalt nitrate hexahydrate are dissolved in deionized water, and heated and stirred at a temperature of 95° C. and a rotation speed of 230 r·min ^-1 to obtain a metal nitrate solution. At the same time, deionized water and ammonia water are added to ethylenediaminetetraacetic acid, and ammonia water and citric acid monohydrate dissolved in ethylenediaminetetraacetic acid are added to the metal nitrate solution, and the temperature is continued to be 95° C. and the rotation speed is 230 r·min ^-1. Stirring until the solution becomes a gel;

c. drying the gel obtained in step b in an oven at 220° C. for 230 min to obtain a precursor;

d. placing the precursor obtained in step c in a muffle furnace for carbon removal, and then calcining under oxygen partial pressure to obtain a powder;

e. Grind the powder obtained in step 4 and sieve it through a 300-mesh sieve to obtain Sr ₄ Fe ₃ Co ₅ O _13+δ (SFC4) cathode material powder with an average particle size of 350 nm.

Example 4

A method for preparing a cathode material for a solid oxide fuel cell comprises the following steps:

a. According to the stoichiometric ratio, weigh strontium nitrate, ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ethylenediaminetetraacetic acid, citric acid monohydrate and ammonia water respectively, and the molar ratio of ethylenediaminetetraacetic acid: citric acid monohydrate: metal cation is 1:2:1;

b. First, strontium nitrate, ferric nitrate nonahydrate and cobalt nitrate hexahydrate are dissolved in deionized water, and heated and stirred at a temperature of 90°C and a rotation speed of 300 r·min ^-1 to obtain a metal nitrate solution. At the same time, deionized water and ammonia water are added to ethylenediaminetetraacetic acid, and ammonia water and citric acid monohydrate dissolved in ethylenediaminetetraacetic acid are added to the metal nitrate solution, and the temperature is continued to be 90°C and the rotation speed is 300 r·min ^-1 . Stirring until the solution becomes a gel;

c. drying the gel obtained in step b in an oven at 250° C. for 250 min to obtain a precursor;

d. placing the precursor obtained in step c in a muffle furnace for carbon removal, and then calcining under oxygen partial pressure to obtain a powder;

e. Grind the powder obtained in step 4 and sieve it with a 300-mesh sieve to obtain Sr ₄ Fe ₃ Co ₄ O _13+δ (SFC4) cathode material powder with an average particle size of 400 nm.

The SFC4 cathode material synthesized in this embodiment was characterized by X-ray diffraction (XRD), and the results are shown in Figure 1. As shown in Figure 1, the SFC4 cathode material is composed of a nanoscale single perovskite phase Sr(Co,Fe)O ₃ , a spinel phase (Co,Fe) ₃ O ₄ , cobalt oxide CoO and strontium carbonate SrCO _3. The Pmcn phase in Figure 1 is the space group of strontium carbonate, which occupies 4.1% of the material. Carbonates can improve the oxygen activation performance and stability of electrode materials, which is one of the important reasons why the single cell prepared by the material can have higher output performance and long-term stable performance. In addition, the single perovskite phase has good electrical conductivity, and the layered perovskite phase has higher electrical conductivity and long-term performance stability, which is the fundamental reason why the single cell prepared by the material can have higher output performance and long-term stable performance.

Comparative Example 1

The remaining steps of this comparative example are the same as those of Example 4, except that the temperature in step b is replaced with 70° C. As a result, it is found that the gel formation rate is greatly reduced.

Comparative Example 2

The remaining steps of this comparative example are the same as those of Example 4, except that the temperature in step b is replaced with 110° C. The results show that the gel is easy to foam at high temperature due to shortened stirring time.

Comparative Example 3

The remaining steps of this comparative example are the same as those of Example 4, except that the temperature of the oven in step c is changed to 180° C. The results show that the organic matter in the gel is insufficiently carbonized.

Comparative Example 4

The remaining steps of this comparative example are the same as those of Example 4, except that the temperature of the oven in step c is replaced with 320° C. The results show that the carbon skeleton is excessively burned.

Example 5

The SFC4 cathode material of Example 4 was used to prepare a SFC4|SDC|SFC4 oxygen ion-based symmetrical battery, and the specific steps were as follows:

(1) 10 ml of isopropanol, 2 ml of ethylene glycol and 0.6 ml of propylene glycol were weighed, and 1 g of SFC4 cathode powder was weighed and placed on a planetary ball mill for ball milling at a speed of 400 r min ^-1 for 2 h to obtain cathode powder slurry;

(2) Weigh 0.5 g of SDC electrolyte powder and press it into a 15 mm disc using a tablet press. Then, calcine it in a high-temperature furnace at about 1400° C. for 5 h to obtain an electrolyte sheet.

(3) using a spray gun to evenly spray the slurry on both sides of the electrolyte sheet, and calcining it in a muffle furnace at about 800° C. for 2 h to obtain a symmetrical battery;

(4) Apply a current collecting layer on both sides of the above oxygen ion-based symmetrical battery and connect them with silver wires.

The SFC4|SDC|SFC4 oxygen ion based symmetric battery prepared in this example was subjected to electrochemical impedance test in air at 550°C, and the result is shown in Figure 2. As shown in Figure 2, the resistance of the SFC4|SDC|SFC4 oxygen ion based symmetric battery at the test temperature of 550°C is ^0.04Ωcm2 .

The thermochemical stability of the SFC4|SDC|SFC4 oxygen ion-based symmetrical battery prepared in this embodiment was tested, and the results are shown in Figure 3. As can be seen from the results in Figure 3, the oxygen ion-based symmetrical battery prepared with the SFC4 cathode material can continue to work for 1000 hours at a test temperature of 550°C, and its impedance does not increase significantly.

Example 6

The SFC4 cathode material of Example 4 is used to prepare a SFC4|SDC|NiO-SDC oxygen ion-based fuel cell, and the specific steps are as follows:

(1) 10 ml of isopropanol, 2 ml of ethylene glycol and 0.6 ml of propylene glycol were weighed, and 1 g of SFC4 cathode powder was weighed and placed on a planetary ball mill for ball milling at a speed of 400 r min ^-1 for 2 h to obtain cathode powder slurry;

(2) Weigh 7 g of NiO powder, 3 g of SDC powder and 0.7 g of PVB into a mortar, add an appropriate amount of alcohol, grind until the alcohol is completely evaporated, then place in an oven to dry, and then place in a mortar and grind into NiO-SDC anode powder.

(3) Weigh 0.35 g of NiO-SDC anode powder and press it into a 15 mm disc using a tablet press. Then weigh 0.015 g of SDC electrolyte powder and evenly sieve it onto one side of the anode powder disc using a 300-mesh sieve. Continue pressing and calcine the pressed disc in a high-temperature furnace at 1400°C for 5 h to obtain a half-cell.

(4) using a spray gun to evenly spray the cathode powder slurry onto the electrolyte side of the half-cell, and calcining it in a muffle furnace at 800° C. for 2 h to obtain an oxygen ion-based fuel cell;

(5) A current collecting layer is applied on the cathode side of the oxygen ion-based fuel cell, silver wires are connected on both sides, and the fuel cell is packaged on a quartz glass tube.

The output performance of the oxygen ion-based fuel cell prepared in this embodiment was tested by using dry _H2 as fuel and air as oxidant at 400°C, 500°C and 600°C respectively using a digital source meter (Keithley2440). The test temperature interval was 50°C. The results are shown in FIG4 . At 600°C, the maximum power density can reach 1250 mW cm ^-2 .

Figure 5 shows the SEM image of the oxygen ion-based fuel cell prepared in this embodiment, including the cross-sectional image shape of the SFC4 porous cathode, the dense SDC electrolyte and the NiO-SDC composite anode. As can be seen from Figure 5, the adhesion between the SFC4 cathode (thickness of about 25 μm) and the SDC electrolyte (thickness of about 20 μm) is very close, thus proving the reliability of the oxygen ion-based fuel cell performance test results.

Example 7

The SFC4 cathode material of Example 4 was used to prepare a SFC4|BZCYYb|SFC4 proton-based symmetric battery, and the specific steps were as follows:

(1) 10 ml of isopropanol, 2 ml of ethylene glycol and 0.6 ml of propylene glycol were weighed, and 1 g of SFC4 cathode powder was weighed and placed on a planetary ball mill for ball milling at a speed of 400 r min ^-1 for 2 h to obtain cathode powder slurry;

(2) About 0.5 g of BZCYYb electrolyte powder was weighed and pressed into a disc with a diameter of 15 mm using a tablet press, and then placed in a high-temperature furnace at about 1450° C. and calcined for 5 h to obtain an electrolyte sheet.

(3) using a spray gun to evenly spray the slurry on both sides of the electrolyte sheet, and calcining it in a muffle furnace at about 800° C. for 2 h to obtain a symmetrical battery;

(4) Apply current collecting layer on both sides of the above-mentioned proton-based symmetrical battery and connect them with silver wires.

The SFC4|BZCYYb|SFC4 proton-based symmetric battery prepared in this example was subjected to electrochemical impedance testing in a humid air (3% H ₂ O) atmosphere at 550°C, and the results are shown in Figure 6. As shown in Figure 6, the resistance of the symmetric battery prepared with the SFC4 cathode material at a test temperature of 550°C is 0.774Ωcm ² .

The thermochemical stability of the SFC4|BZCYYb|SFC4 proton-based symmetric battery prepared in this example was tested, and the results are shown in Figure 7. As shown in Figure 7, the SFC4|BZCYYb|SFC4 proton-based symmetric battery can continue to work for 1000 hours at a test temperature of 550°C, and its impedance increases at a rate of 4/10000Ωcm2 ^/ h.

Example 8

The preparation method of the SFC4|BZCYYb|SFC4 proton ceramic fuel cell in this embodiment has the following specific steps:

(1) 10 ml of isopropanol, 2 ml of ethylene glycol and 0.6 ml of propylene glycol were weighed, and 1 g of SFC4 cathode powder was weighed and placed on a planetary ball mill for ball milling at a speed of 400 r min ^-1 for 2 h to obtain cathode powder slurry;

(2) Weigh 6 g of NiO powder, 4 g of BZCYYb powder and 1 g of starch into a ball mill, add an appropriate amount of alcohol, and place the mixture on a planetary ball mill at a speed of 400 r min ^-1 for 40 min. Pour the milled slurry into a mortar and grind until all the alcohol is evaporated. Then place the mixture in an oven to dry, and then place the mixture in a mortar and grind it into NiO-BZCYYb anode powder.

(3) Weigh 0.35 g of NiO-BZCYYb anode powder and press it into a 15 mm disc using a tablet press. Then weigh 0.015 g of BZCYYb electrolyte powder and evenly sieve it onto one side of the anode powder disc using a 300-mesh sieve. Continue pressing. The pressed disc is placed in a high-temperature furnace at 1450°C and calcined for 10 h to obtain a half-cell.

(4) using a spray gun to evenly spray the cathode powder slurry onto the electrolyte side of the half-cell, and calcining it in a muffle furnace at 800° C. for 2 h to obtain a proton ceramic fuel cell;

(5) Apply a current collecting layer on the cathode side of the above single cell, connect silver wires on both sides, and encapsulate it in a quartz glass tube.

The output performance of the proton ceramic fuel cell prepared in this embodiment was tested by using wet H ₂ (3% H ₂ O) as fuel and air as oxidant at 350°C, 450°C and 550°C respectively using a digital source meter (Keithley 2440). The results are shown in FIG8 . At 550°C, the maximum power density can reach 645 mW cm ^-2 .

Figure 9 shows the SEM image of the proton ceramic fuel cell prepared in this embodiment, including the cross-sectional image shape of the SFC4 porous cathode, the dense BZCYYb electrolyte and the NiO-BZCYYb composite anode. It can be clearly seen from the figure that the adhesion between the SFC4 cathode (thickness of about 30μm) and the BZCYYb electrolyte (thickness of about 25μm) is still very close, which also proves the reliability of the proton ceramic fuel cell performance test results.

The proton ceramic fuel cell prepared in this embodiment was subjected to a thermochemical stability test. The specific method is: using dry _H2 as fuel and air as oxidant at a temperature of 550°C using a digital source meter (Keithley 2440) to perform a stability test. The results are shown in FIG10 . At a test temperature of 550°C, the fuel cell can continue to work stably for 3100 hours.

Claims (9)

_1. An application of a solid oxide fuel cell cathode material in a low-temperature oxygen ion conductor-based solid oxide fuel cell, characterized in that: _{Sr4FexCoyO13 +δ} is used as the cathode, samarium oxide-doped cerium oxide is used as the electrolyte, and a mixture of NiO and _SDC is _used as the anode; the chemical formula of the solid oxide fuel cell cathode material is _{Sr4FexCoyO13 +δ} , wherein 0<x< ₄ , 2<y<6, δ is the oxygen vacancy concentration, and 0<δ<1. 2. The use of a solid oxide fuel cell cathode material according to claim 1 in a low-temperature oxygen ion conductor-based solid oxide fuel cell, characterized in that the average particle size of the cathode material is 300~500nm. 3. The use of a solid oxide fuel cell cathode material in a low-temperature oxygen ion conductor-based solid oxide fuel cell according to claim 1, characterized in that the preparation method of the solid oxide fuel cell cathode material comprises the following steps: Step 1, weighing strontium nitrate, ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ethylenediaminetetraacetic acid, citric acid monohydrate and ammonia water respectively according to the stoichiometric ratio; Step 2, dissolving the above raw materials in deionized water in sequence, and heating and stirring until they are in a gel state; Step 3, drying the product obtained in step 2 to obtain a precursor; Step 4, decarbonizing the precursor obtained in step 3, and then calcining it under oxygen partial pressure to obtain a powder; Step 5: Grind the powder obtained in step 4 to obtain Sr ₄ Fe _x Co _y O _13+δ cathode material powder. 4. The use of a solid oxide fuel cell cathode material in a low-temperature oxygen ion conductor-based solid oxide fuel cell according to claim 3, characterized in that: in the step 1, the molar ratio of ethylenediaminetetraacetic acid: citric acid monohydrate: metal cation is 1:2:1-2, and the molar number of the metal cation is the sum of the molar numbers of strontium nitrate, ferric nitrate nonahydrate, and cobalt nitrate hexahydrate. 5. The use of a solid oxide fuel cell cathode material in a low-temperature oxygen ion conductor-based solid oxide fuel cell according to claim 3, characterized in that: in the step 2, strontium nitrate, ferric nitrate nonahydrate, and cobalt nitrate hexahydrate are first dissolved in deionized water, heated and stirred to obtain a metal nitrate solution, and then ethylenediaminetetraacetic acid is dissolved in ammonia water, and ammonia water and citric acid monohydrate dissolved in ethylenediaminetetraacetic acid are added to the metal nitrate solution, and heating and stirring are continued until it is in a gel state. 6. The use of a solid oxide fuel cell cathode material in a low-temperature oxygen ion conductor-based solid oxide fuel cell according to claim 3, characterized in that: in the step 2, the heating temperature is 80-100°C, and the stirring speed is 200-300 r·min ^-1 . 7. The use of a solid oxide fuel cell cathode material in a low-temperature oxygen ion conductor-based solid oxide fuel cell according to claim 3, characterized in that: in the step three, the drying temperature is 200-300°C and the time is 200-300 minutes. 8. The use of a solid oxide fuel cell cathode material in a low-temperature oxygen ion conductor-based solid oxide fuel cell according to claim 3, characterized in that: in the step 5, after grinding, the material is sieved with a 200-400 mesh sieve. 9. An application of a solid oxide fuel cell cathode material in a low-temperature proton ceramic fuel cell, characterized in that: Sr ₄ Fe _x Co _y O _13+δ is used as the cathode, BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ is used as the electrolyte, and a mixture of NiO and BZCYYb is used as the anode; the chemical formula of the solid oxide fuel cell cathode material is Sr ₄ Fe _x Co _y O _13+δ , wherein 0<x<4, 2<y<6, δ is the oxygen vacancy concentration, and 0<δ<1.