CN103208634B - For the composite cathode material of middle low-temperature protonic transmission Solid Oxide Fuel Cell - Google Patents

Abstract

The invention discloses a composite cathode material for a medium-low temperature proton transport solid oxide fuel cell, belonging to the field of fuel cells. The present invention is characterized in that: BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ with high conductivity of oxygen ions and electrons and BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O ₃ -δ with high conductivity of protons are used to compound each other to prepare a new type of cathode material, whose chemical formula is BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ -BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ , where the ratio of the two phases can be varied. The cathode material of the invention can be used in medium and low temperature proton transport solid oxide fuel cells. After BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ is combined with BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ , the cathode material has oxygen ion, proton and electron conduction properties at the same time, the three-phase interface is expanded, and the electrode performance is good, among which The two phases have good chemical compatibility and stable performance. The presence of Co in the BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ phase makes the electrode material have good electrocatalytic performance, which can reduce the interface resistance of the battery and improve the work of the battery. characteristic.

Description

Composite cathode materials for medium and low temperature proton transport solid oxide fuel cells

technical field

The invention belongs to the field of fuel cells, and in particular relates to a battery consisting of BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ with relatively high conductivity of oxygen ions and electrons and BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O ₃ -δ with high proton conductivity. High-performance composite cathode materials for proton transport solid oxide fuel cells formed by _δ composites.

Background technique

Due to the high operating temperature of traditional solid oxide fuel cells, it puts forward strict requirements on electrode materials and connecting materials, resulting in poor stability and short life, which greatly limits its commercial development process. Therefore, reducing the operating temperature and developing medium and low temperature solid oxide fuel cells have become the main trend of solid oxide fuel cell development.

Solid oxide fuel cells are mainly divided into two categories: traditional oxygen ion transport solid oxide fuel cells (O-SOFC) and proton transport solid oxide fuel cells (H-SOFC). Compared with the activation energy of oxygen ion migration in O-SOFC, the activation energy of proton transport in H-SOFC is lower, therefore, H-SOFC can work at lower temperature. At the same time, according to the working principle of H-SOFC, the by-product water of the reaction is produced on the cathode side instead of the anode side of O-SOFC, so the water treatment process of O-SOFC can be omitted, the equipment structure can be simplified, and the working efficiency of SOFC can be improved. Therefore, H-SOFC has become one of the research focuses in the field of developing medium and low temperature solid oxide fuel cells.

The cathode material is one of the key materials that determine the overall performance of the battery. In SOFC, the cathode material needs to have high structural stability in an oxidizing atmosphere, strong catalytic activity, and high electronic and ion conductivities. Compared with O-SOFC cathode materials, the types and related theories of H-SOFC cathode materials are developed later. Therefore, whether in terms of practical application or theoretical research, H-SOFC mainly follows the relevant content of O-SOFC. But in fact, for the selection of cathode materials, it is necessary to consider its working principle, function and working environment at the same time. Unlike O-SOFC, processes such as the formation and diffusion of water in H-SOFC occur on the cathode side. Therefore, compared with O-SOFC, which requires that the cathode material preferably have the ability to transport oxygen ions and electrons, H-SOFC also requires that the cathode The material preferably has the ability to transport protons at the same time, that is, it has good ability to transport protons, oxygen ions and electrons at the same time.

As far as the current research on H-SOFC is concerned, the more common cathode materials are mainly electron conductors, oxygen ion-electron mixed conductors and proton-electron mixed conductors. The first type of electron conductor cathode material only conducts electrons, such as La _{1- x} Sr _x MnO _3-δ (LSM), which has high electronic conductivity (>100 S cm ^-1 ), but its ionic conductivity is very low, at 900 ^o C It is only 5.9×10 ^-7 S cm ^-1 , and it is a pure electronic conductor (I. Yasuda, K. Ogasawara, et al. Solid StateIonics 86-88 (1996): 1197-1201). Among these materials Only electrons can achieve bulk diffusion, while oxygen ions and protons can only diffuse on the surface, so the three-phase interface area is very limited. The second type is oxygen ion-electron mixed conductors, such as perovskite La _lx Sr _x CoO _3-δ (LSC) (RA De Souza, JA Kilner. Solid State Ionics 106(1998): 175-187). The material has high electron conductance and oxygen ion conductance at the same time, but its proton transport is limited, and its three-phase interface area is also small, which is not conducive to improving its electrochemical reaction rate. The third type is the proton-electron mixed conductor, and there are only a few materials at present, such as BaCeO ₃ -based cathode materials doped with Fe and Bi elements at the B site (Z. Tao, L.Bi, et al. Electrochemistry Communication 11 ( 2009): 688-690), but due to the limited transport of oxygen ions in this type of material, the three-phase interface cannot be expanded, and the performance of the electrode is affected.

If the H-SOFC cathode material has the conductivity of oxygen ions, protons and electrons at the same time, the three-phase interface will be greatly expanded, the diffusion distance of oxygen ions, protons and electrons will be greatly shortened, and the kinetic process of the electrode reaction will be accelerated. In addition, if the cathode material has good and stable catalytic performance at the same time, the working stability and electrochemical reaction rate of the electrode will be guaranteed. Therefore, the present invention selects BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ which has higher oxygen ion and electron conductance and better catalytic activity and BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ which has higher proton conductivity. Composite, a high-performance cathode material for H-SOFC was prepared.

Contents of the invention

The purpose of the invention is to prepare a novel oxygen ion-proton-electron conductive composite cathode material with high catalytic activity. The scheme is to combine the oxygen ion-electron conductor phase and the proton conductor phase to expand the three-phase reaction area of the electrode, thereby reducing the electrode polarization, accelerating the electrochemical reaction process of the electrode, and increasing the output power of the battery.

The present invention combines the oxygen ion-electron conductor phase BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ with high oxygen ion surface exchange coefficient, high oxygen ion and electron conductivity, and the proton conductor phase BaZr _0.1 Ce _0.7 Y with high proton conductivity _0.1 Yb _0.1 O _3-δ composite to form BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ -BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ composite cathode material.

The composite cathode material is used for medium and low temperature proton transport solid oxide fuel cells. In a humid air atmosphere at 750 ^o C, the composite cathode with BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ content of 60 wt% has an area specific resistance of 0.35 Ω cm ² . At the test temperature of 750 ^o C, BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ with a thickness of 60 μm was used as the electrolyte, NiO-BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ as the anode, and BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ content of 60 wt% BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ -BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ as the cathode, the maximum output power of the anode-supported battery is 123 mW cm ^-2 .

Materials provided in the present invention can be prepared as follows:

a. BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ powder is synthesized by solid state method. Weigh an appropriate amount of BaCO ₃ , Nb ₂ O ₅ , Fe ₂ O ₃ , Co(CH ₃ COO) ₂ ･4H ₂ O as raw materials according to the stoichiometric ratio, and put the raw material mixture into a ZrO ₂ ball mill tank with alcohol as the medium Ball milling for 4-8 h with a rotating speed of 200-600 r/min to mix the raw materials evenly, put the suspension of the mixture in a glass dish, dry in an oven, and heat-treat at 900-1300 ^o C for 8-12 h. Obtain a pure-phase perovskite structure oxide, and then put the obtained oxide into a ball mill jar to grind for 2~6 h, and the obtained BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ finer powder is used as the oxygen ion of the composite cathode - proton phase.

b. BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ was synthesized by citric acid-nitrate method. Dissolve an appropriate amount of Yb ₂ O ₃ in concentrated nitric acid solution, heat in a water bath, and after complete dissolution, mix Ba(NO ₃ ) ₂ , Ce(NO ₃ ) ₃ •6H ₂ O, Zr(NO ₃ ) ₄ according to the stoichiometric ratio • 5H ₂ O and Y(NO ₃ ) ₃ • 6H ₂ O are added to the nitrate solution. In order to complete the complexation, ethylenediaminetetraacetic acid (EDTA) and citric acid monohydrate are simultaneously added to the solution as complexing agents, among which The ratio range of metal ions and citric acid is 1:1~1:2, the ratio of metal ions and EDTA is 1:0.8~1:1.2, the pH is adjusted to 7~9, and the solution is mixed evenly with a magnetic stirrer. Heat in a water bath at ~90 ^o C to evaporate the excess water to obtain a gel-like liquid; put the gel-like liquid into a porcelain cell and heat it on a resistance wire furnace until it is completely burned to obtain an oxide precursor, a precursor The body was treated in an air atmosphere at 800~1200 ^o C for 4~8 h, and a single perovskite phase of BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ was obtained.

c. Using absolute ethanol as a medium, mix the two phases with a mass ratio of 3:7 to 7:3, and grind them in a mortar until uniform, to obtain a composite cathode material.

d. Add 10-50 vol% combustible substances to the obtained composite cathode material fine powder. The combustible substances include carbon powder, starch, corn flour, and resin, and then dry press or semi-dry press to form, and then press at 1050-1350 ^o Calcining at C temperature for 2~6 h can prepare porous cathode block; or add water, soluble starch and ethyl cellulose to the obtained composite cathode powder to make slurry, and use screen printing method to coat it evenly On the surface of the dense BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ electrolyte sheet, calcined at 1050~1350 ^o C for 2~6 h to make porous BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ -BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ composite cathode film.

The present invention has the advantage of preparing a novel composite cathode material BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ -BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ for medium and low temperature proton transport solid oxide fuel cells . The oxygen ion-electron conductor phase is BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ containing Co. In general, Co-containing materials have good electrocatalytic properties. In addition, for the problems of large thermal expansion coefficient and unstable structure in general Co-containing materials, studies have shown that when doping a small amount of Fe and a small amount of Nb in the BaCoO _3-δ matrix to form BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ , an appropriate amount of doping Impurities can effectively inhibit the phase transition of the material, so that the material still maintains a cubic perovskite structure at room temperature, and can generate a higher concentration of oxygen vacancies in the material to promote the conduction of oxygen ions (YF Cheng , HL Zhao, et al . Journal of Membrane Science 322 (2008):484-490). In addition, the high electrocatalytic activity and high oxygen ion conductivity of the material can significantly promote the improvement of electrode performance. For example, when SDC is used as the electrolyte and BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ is used as the cathode, it shows Higher electrode performance (CJ Zhu, XM Liu, et al. Electrochemistry Communications 11 (2009):958-961). At the same time, the proton conductor phase in the present invention is BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ , and its proton conductivity is higher than the traditional oxygen ion conductor electrolyte material and the commonly used proton conductor BaZr _0.1 Ce _0.7 Y _0.2 O _3-δ , and has good resistance to sulfur poisoning and carbon deposition. The composite cathode material combines the advantages of the two materials. In addition, its preparation method is to mix the electrolyte material into the traditional cathode material, which can adjust the thermal expansion coefficient of the electrode, enhance its bonding strength with the electrolyte diaphragm, and increase its working stability. At the same time, compounding has achieved the effect of expanding the three-phase reaction interface.

Description of drawings

Figure 1 shows BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ powder calcined at 1000 ^o C for 6 h, BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ powder calcined at 1100 ^o C for 10 h and BaCo _0.7 Fe _0.22 Nb X-ray diffraction curves of _0.08 O _3-δ content of 50 wt% BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ -BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ composite cathode material calcined at 1200 ^o C for 3 h picture;

Fig. 2 is a graph showing the relationship between polarization resistance and test temperature of a symmetrical battery composed of different ratios of BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ -BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ composite cathode materials.

detailed description

Below in conjunction with embodiment the present invention will be further described, but not limited to protection scope of the present invention:

Example 1: Synthesis and chemical compatibility test of a composite cathode material with BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ accounting for 50 wt%

According to the stoichiometric ratio of BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ , weigh an appropriate amount of BaCO ₃ , Nb ₂ O ₅ , Fe ₂ O ₃ , Co(CH ₃ COO) ₂ ･4H ₂ O as raw materials, and use alcohol as the medium , put the raw material mixture into a ZrO ₂ ball mill jar and mill for 6 h at a speed of 400 r/min to mix the raw materials evenly, put the suspension of the mixture in a glass dish, dry it in an oven, and heat it at 1100 ^o C Heat treatment for 10 h to obtain a pure-phase perovskite structure oxide, and then put the obtained oxide into a ball mill jar for grinding for 4 h to obtain a finer powder as the oxygen ion-proton phase BaCo _0.7 Fe required for the preparation of a composite cathode _0.22 Nb _0.08 O _3-δ . To prepare BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ , weigh an appropriate amount of Yb ₂ O ₃ , dissolve Yb ₂ O ₃ in concentrated nitric acid solution, heat in a water bath, and dissolve Ba( NO ₃ ) ₂ , Ce(NO ₃ ) ₃ • 6H ₂ O, Zr(NO ₃ ) ₄ • 5H ₂ O and Y(NO ₃ ) ₃ • 6H ₂ O were added to the nitrate solution. For complete complexation, EDTA Add citric acid monohydrate into the solution at the same time as a complexing agent, add the metal ion, citric acid and EDTA into the above aqueous solution at a ratio of 1:1.5:1, adjust the pH to 8, and mix the solution evenly with a magnetic stirrer , heated in a water bath at 80 ^o C to evaporate the excess water to obtain a gel-like liquid; put the gel-like liquid into a porcelain cell and heat it on a resistance wire furnace until it is completely burned to obtain the oxide precursor, the precursor The body was treated in an air atmosphere at 1000 ^o C for 6 h to obtain a single perovskite phase BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ .

After the two powders are synthesized, weigh the two substances of the same mass, mix the two phases with absolute ethanol as the medium, and grind them in a mortar until they are uniform to obtain a composite cathode material, which is then formed into a sheet by dry pressing The green body was calcined at 1200 ^o C for 3 h, and the XRD test results showed (as shown in Figure 1) that no obvious impurity peaks appeared after the composite material was calcined, indicating that there was no obvious reaction between the two phases in the range of 1200 ^o C, and there was a strong Good chemical compatibility.

Example 2: Measurement of polarization resistance of BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ -BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _{3-δ -BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ} in two phases with different ratios

The two-phase materials were uniformly mixed according to the mass ratio of BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ : BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ 6:4, 5:5 and 4:6 to obtain composite cathode powder. Mix the composite cathode powder and pore-forming agent soluble starch evenly at a mass ratio of 8:2, then add terpineol containing 10% ethyl cellulose as a binder to the powder, and the powder and binder The mass ratio is 6:4. The mixture was thoroughly ground until a homogeneous viscous cathode material slurry was obtained. The slurry was evenly coated on the surface of the dense BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ electrolyte sheet by screen printing method, and after drying in an oven, it was placed in a high-temperature furnace and calcined at 1200 ^o C for 3 h, get a symmetrical battery.

The electrochemical impedance spectroscopy was tested on the symmetrical battery, the instrument used was Solartron1260 frequency response analyzer, and the polarization process of the electrode and the conductivity of the electrode material were characterized by using the 1287 electrochemical interface. Symmetrical cells were tested at test temperatures of 550, 600, 650, 700 and 750 ^o C, with a disturbance voltage of 5 mV and a frequency range of 1 MHz to 0.01 Hz. Using ZsimpWin software to fit the obtained data, after data analysis, the Arrhenius curve of polarization resistance was obtained. It can be seen from Figure 2 that with the increase of BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ content in the composite cathode, the interface resistance gradually decrease. The area specific resistance of the composite cathode with BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ content of 60 wt% in humid air atmosphere at 750 ^o C is 0.35 Ω cm ² .

Example 3: Preparation of anode-supported batteries composed of composite electrodes with different ratios and voltage-current density-power density curve test

BaCe _0.7 Zr _0.1 Y _0.1 Yb _0.1 O _3-δ , NiO and soluble starch were mixed according to the mass ratio of 4:6:2, ball milled with absolute ethanol as the medium, and anode powder was obtained after drying. An appropriate amount of PVA is added to the body for dry pressing, and a small amount of electrolyte powder BaCe _0.7 Zr _0.1 Y _0.1 Yb _0.1 O _3-δ is evenly screened and sprinkled on one side of the formed anode body, and the anode-electrolyte double layer is formed by secondary dry pressing. The billet was calcined at 1350 ^o C to obtain a circular diaphragm with dense electrolyte.

The two-phase materials were uniformly mixed according to the mass ratio of BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ : BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ 6:4, 5:5 and 4:6 to obtain composite cathode powder. Mix the composite cathode powder and the pore-forming agent soluble starch uniformly at a mass ratio of 8:2, and then add a mixed solution of terpineol containing 10% ethyl cellulose as a binder to the uniformly mixed powder, The ratio of powder and binder is 6:4 by mass. The mixture was thoroughly ground until a homogeneous viscous cathode material slurry was obtained.

The viscous cathode slurry is uniformly coated on the electrolyte by screen printing. The obtained body was calcined at 1200 ^o C for 2 h in an air atmosphere to obtain an anode-supported battery. Using platinum paste as a current collector and connecting agent, the wire is connected to the cathode and anode. The battery was encapsulated with water glass (Cerama-bond552-VFG, Aremco) at high temperature. Put the alumina ceramic tube with a battery fixed at one end into the resistance furnace, adjust the position so that it is in the constant temperature zone of the resistance furnace, and connect it to the external circuit. Raise the temperature, pass water-through H ₂ as fuel gas at the anode side of the battery, the flow rate is 60 ml min ^-1 , and pass natural air at the cathode side. During the experiment, by changing the load of the external circuit, the output performance of the battery was obtained by testing the voltage and current at both ends of the load under different loads. After processing the data, the voltage-current ^density -power density curve was obtained. 60 μm thickness of BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ as electrolyte, NiO-BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ as anode, BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ content 60 wt% BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ -BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ as the cathode, the maximum output power of the anode-supported battery is 123 mW cm ^-2 .

Claims (2)

1. A composite cathode material for medium and low temperature proton transport solid oxide fuel cells, characterized in that: the oxygen ion-electron conductor phase BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ and the proton conductor phase BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ recombines each other to form a composite cathode material BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ -BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ , in which the mass ratio of the two phases varies from 3:7 to 7:3; the composite cathode material for medium and low temperature proton transport solid oxide fuel cells is prepared by the following method, including the steps: a. BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ powder is synthesized by solid phase method: weigh appropriate amount of BaCO ₃ , Nb ₂ O ₅ , Fe ₂ O ₃ , Co(CH ₃ COO) ₂ ·4H ₂ according to the stoichiometric ratio O is the raw material, and alcohol is used as the medium, and the raw material mixture is put into a ZrO2 ball mill tank for ₄ to 8 hours, and the rotation speed is 200 to 600r/min, so that the raw materials are mixed evenly, and the mixture suspension is placed in a glass dish. After drying in an oven, heat treatment at 900-1300°C for 8-12 hours to obtain a pure-phase perovskite structure oxide, and then put the obtained oxide into a ball mill jar for grinding for 2-6 hours to obtain BaCo _0.7 Fe _0.22 Nb _0.08 The finer powder of O _3-δ is used as the oxygen ion-proton phase of the composite cathode; b. BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ was synthesized by citric acid-nitrate method: Dissolve an appropriate amount of Yb ₂ O ₃ in concentrated nitric acid solution, heat in a water bath, and after complete dissolution, Ba (NO ₃ ) ₂ , Ce(NO ₃ ) ₃ ·6H ₂ O, Zr(NO ₃ ) ₄ ·5H ₂ O and Y(NO ₃ ) ₃ ·6H ₂ O were added to the nitrate solution, for complete complexation, Ethylenediaminetetraacetic acid (EDTA) and citric acid monohydrate are simultaneously added to the solution as complexing agents, wherein the ratio of metal ions to citric acid ranges from 1:1 to 1:2, and the ratio of metal ions to EDTA is 1:0.8 ~1:1.2, adjust the pH to 7~9, use a magnetic stirrer to mix the solution evenly, heat in a water bath at 20~90°C to evaporate the excess water, and obtain a gel-like liquid; put the gel-like liquid into the porcelain element In a dish, heat it on a resistance wire furnace until it is completely burned to obtain an oxide precursor. The precursor is treated in an air atmosphere at 800-1200°C for 4-8 hours to obtain a single perovskite phase BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ ; c. Using absolute ethanol as a medium, mix the two phases with a mass ratio of 3:7 to 7:3, and grind them in a mortar until they are uniform, so as to obtain a composite cathode material. 2. The use of BaCo _0.7 Fe _0.22 Nb _0.08 O _3-δ- BaZr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ composite cathode material according to claim 1, which is used for medium and low temperature proton transport solid oxide fuel Battery.