Cathode material, preparation method and application thereof

Abstract

This invention discloses a cathode material, its preparation method, and its applications, belonging to the field of batteries. The cathode material of this invention has a core-shell structure, where the core contains a noble metal, and the shell contains a perovskite structure, a spinel structure, or a combination thereof; the shell covers the surface of the core; the ratio of the shell thickness to the core particle size is 1 to 10. This invention prepares a core-shell structured cathode material by coating a noble metal core with a material having a perovskite structure, a spinel structure, or a combination thereof, and ensuring that the shell thickness is in a certain proportion to the core particle size, thereby improving the conductivity of the cathode material and ensuring that the thermal expansion properties of the cathode material are matched with those of the electrolyte and connecting materials. Therefore, the cathode material provided by this invention has wide applications in the field of batteries, especially in the field of solid oxide fuel cells.

Description

Technical Field

[0001] This invention belongs to the field of batteries, and particularly relates to a cathode material, its preparation method, and its application. Background Technology

[0002] In today's world, energy issues are becoming increasingly prominent, and environmental pollution is intensifying. Developing new energy sources and reducing greenhouse gas emissions have gradually become a focus of attention. Fuel cells directly convert the chemical energy of fuel into electrical energy, reducing mechanical work and energy transfer processes. Their energy conversion efficiency reaches 45%–60%, and they do not produce greenhouse gases such as sulfur and nitrogen during the energy conversion process, resulting in less environmental pollution. They also operate stably and have a long service life, earning them the title of green energy. Solid oxide fuel cells (SOFCs) possess advantages such as high efficiency, environmental friendliness, low cost, convenience, and quiet operation, making them the most promising power generation device of the 21st century.

[0003] Traditional SOFCs typically operate at temperatures between 800 and 1000°C. However, high temperatures impose stringent requirements on SOFC materials, limiting the range of electrode and connector materials that can be selected. Therefore, recent research has focused on the development of medium- and low-temperature SOFCs. However, at lower operating temperatures, the conductivity of commonly used electrode materials also decreases. The main requirements for SOFC cathode materials are: (1) high catalytic activity; (2) high electrical conductivity to reduce ohmic polarization loss of the electrode; (3) chemical compatibility, thermal expansion matching, and good adhesion with the electrolyte material; and (4) good chemical and thermal stability.

[0004] As a commonly used cathode catalyst and cathode electrical connection material, La 1-x Sr x MnO 3-δ LSM has a good match between its coefficient of thermal expansion and that of electrolyte materials, and it also has good chemical and thermal stability. However, as a pure electronic conductor, its electronic conductivity is poor. At 800℃, the conductivity of LSM is only 170 S / cm. In practical applications, it often needs to be mixed with pure ionic conductors such as YSZ, GDC, SDC, and YDC to increase ionic conductivity, which leads to even worse electronic conductivity.

[0005] CN103022532A provides a cathode-side current collector for SOFCs, which is formed from perovskite and noble metals (such as silver). This reduces cost, improves the conductivity of the current collector, effectively collects electrons generated by the electrodes, and reduces the contact resistance between the cathode and the current collector. The current collector is composited with a first coating and a second coating. The first coating has the same composition as the current collector and exhibits consistent thermal deformation, maintaining a tighter contact and effectively reducing the detachment of the cathode and connector caused by thermal effects, thus reducing contact resistance. Simultaneously, no chemical reaction occurs between the current collector and the first coating interface, ensuring stable properties. The contact layer also includes a second coating formed from nickel-containing metal, which contacts the connector. The second coating has a similar composition to the connector, maintaining tight contact and preventing detachment. However, at high temperatures, the silver contained in the current collector and the first coating is prone to softening, diffusion, and migration, ultimately leading to silver blockage of the active sites of the cathode catalyst, affecting the long-term operation of the battery, and the coefficient of thermal expansion can reach 22 × 10⁻⁶. -5 / K can easily lead to a mismatch in the coefficient of thermal expansion with the electrolyte and other coatings.

[0006] US20090029199A1 discloses a SOFC cathode assembly that is cylindrical and includes a cathode and a current collector. The current collector may include a core and a sheath material surrounding at least a portion of the core. The core may include a metal, such as copper, nickel, a mixture or alloy, or a precious metal, such as silver, platinum, or gold. When present, the sheath material may be ceramic, such as LSC (lanthanum-strontium-chromium oxide). The sheath material is not mandatory; for example, it may not be necessary for precious metals. However, this cathode structure has higher manufacturing costs, and without a sheath material, the current collector structure may not match the coefficient of thermal expansion of the electrolyte material and other coatings, while the presence of a sheath material may reduce the conductivity of the cathode material. Summary of the Invention

[0007] In order to overcome the problems existing in the prior art, one of the objectives of the present invention is to provide a cathode material that uses materials with perovskite structure and spinel structure to coat a noble metal core, thereby improving the conductivity of the cathode material and ensuring that the thermal expansion properties of the cathode material are matched with those of the electrolyte and the connecting material.

[0008] The second objective of this invention is to provide a method for preparing the above-mentioned cathode material.

[0009] A third objective of this invention is to provide an application of the above-mentioned cathode material or the method for preparing the above-mentioned cathode material in the field of batteries.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A first aspect of the present invention provides a cathode material having a core-shell structure, wherein the core comprises a noble metal, and the shell comprises a perovskite structure, a spinel structure, or a combination thereof; the shell covers the surface of the core; and the ratio of the thickness of the shell to the particle size of the core is 1 to 10.

[0012] Encapsulating the core material with a shell material prevents low-melting-point metals from melting and leaking when temperatures rise, thus ensuring the overall conductivity of the cathode material. When the ratio of shell thickness d1 to core particle size d2 is less than 1 (i.e., the shell is too thin and the core is too large), the shell is prone to cracking, exposing the core; and excessive use of precious metals increases costs. When the ratio is greater than 10 (i.e., the shell is too thick and the core is too small), the conductivity of the cathode material is affected. When the ratio of shell thickness d1 to core particle size d2 is controlled within the range of 1 to 10, the cathode material is in a more stable state, the shell is less prone to cracking, and the cathode material exhibits superior conductivity.

[0013] Preferably, in the cathode material, the ratio of the shell thickness to the core particle size is 1 to 8; more preferably, in the cathode material, the ratio of the shell thickness to the core particle size is 1 to 5; even more preferably, in the cathode material, the ratio of the shell thickness to the core particle size is 1 to 3.

[0014] Preferably, the noble metal in the cathode material includes at least one of gold, silver, platinum, ruthenium, rhodium, palladium, osmium, or iridium; more preferably, the noble metal in the cathode material includes at least one of silver, ruthenium, rhodium, palladium, osmium, or iridium; even more preferably, the noble metal in the cathode material includes at least one of silver, ruthenium, rhodium, or palladium; more preferably, the noble metal in the cathode material includes at least one of silver or ruthenium.

[0015] Preferably, the precious metal is selected from elemental precious metals.

[0016] Preferably, the precious metal element includes at least one of gold, silver, platinum, ruthenium, rhodium, palladium, osmium, or iridium; more preferably, the precious metal element includes at least one of silver, ruthenium, rhodium, palladium, osmium, or iridium; even more preferably, the precious metal element includes at least one of silver, ruthenium, rhodium, or palladium; and more preferably, the precious metal element includes at least one of silver or ruthenium.

[0017] Using precious metals as the core of the cathode material ensures that the cathode material has good electrical conductivity.

[0018] Preferably, in the cathode material, the perovskite structure includes LSM(La) 1-x Sr x MnO 3-δ), LSCF (La 1- x Sr x Co 1-y Fe y O 3-δ ), LSF (La 1-x Sr x FeO<于 3-δ ), LNF (LaNi x Fe 1-x O 3-δ ), or YCM (Y<00%00020>Ca<000002x>MnO 3-δ ), where at least one of 0 < x < 1, 0 < y < 1, 0 ≤ δ < 1; further preferably, in the cathode material, the perovskite structure includes at least one of LSM, LSCF, LSF, or YCM; more preferably, in the cathode material, the perovskite structure includes at least one of LSM, LSCF, or YCM.

[0019] Preferably, in the cathode material, the spinel structure includes at least one of MnCo2O4, CoMn2O4, CoFe2O4, Co3O4, NiFe2O4, CuFe2O4, Mn 1.5 Co 1.5 O4, MnCo 2-x Fe x O4, or LiMn 2-x M x O4, where M includes at least one of Ni, Mg, Cu, Co, Zn, Cr, Fe, Zr, 0 < x < 1; further preferably, in the cathode material, the spinel structure includes at least one of MnCo2O4, CoMn2O4, CoFe2O4, Co3O4, NiFe2O4, CuFe2O4, or Mn 1.5 Co 1.5 O4; more preferably, in the cathode material, the spinel structure includes at least one of MnCo2O4, CoMn2O4, CoFe2O4, or Co3O4.

[0020] When the perovskite structure is used as the shell in the present invention, it can make the thermal expansion coefficients of the cathode, electrolyte, and other coatings more matched, and retain the good chemical stability and thermal stability possessed by the perovskite structure material.

[0021] It should be noted that there are some inaccuracies in the original text such as "<于 3-δ " and "<00%00020>", which are maintained as they are in the translation for the purpose of following the rules. You may want to check and correct these in the original content for a more accurate technical expression.Because some precious metals have low melting points and high coefficients of thermal expansion, they may melt or expand excessively during cathode fabrication and at fuel cell operating temperatures, leading to reduced single-cell efficiency or even failure. This invention proposes a cathode material with a precious metal core and at least a portion of the shell having a perovskite or spinel structure. This core-shell cathode material can not only lock in precious metals with low melting points, such as gold and silver, at fuel cell operating temperatures, but also limit their thermal expansion at high temperatures. Therefore, this core-shell cathode material can retain the good thermal expansion characteristics of the outer shell material, retain the ultra-high conductivity of the precious metal core, and prevent the diffusion of precious metals at high temperatures.

[0022] Preferably, in the cathode material, the core accounts for 5-95% of the mass fraction of the cathode material; more preferably, in the cathode material, the core accounts for 25-90% of the mass fraction of the cathode material; and even more preferably, in the cathode material, the core accounts for 50-80% of the mass fraction of the cathode material.

[0023] When the mass percentage of the noble metal core is less than 5%, the conductivity of the formed cathode is poor. When the mass percentage of the noble metal core is greater than 95%, the core-shell structure of the prepared cathode is incomplete, the shell cannot lock the noble metal core well, and the thermal expansion coefficient of the formed cathode differs greatly from that of the electrolyte.

[0024] Preferably, the particle size of the core in the cathode material is 5-500 nm; more preferably, the particle size of the core in the cathode material is 50-400 nm; and even more preferably, the particle size of the core in the cathode material is 100-300 nm.

[0025] Preferably, the thickness of the shell in the cathode material is 5-5000 nm; more preferably, the thickness of the shell in the cathode material is 50-4000 nm; and even more preferably, the thickness of the shell in the cathode material is 500-3000 nm.

[0026] A second aspect of the present invention provides a method for preparing the cathode material described in the first aspect of the present invention. The preparation method includes the following steps: stirring a noble metal, a salt solution, and a complexing agent to obtain a mixture, and then subjecting the mixture to a hydrothermal reaction to obtain a precipitate, which is the cathode material; the salt solution includes a salt solution containing rare earth elements, a salt solution containing transition metal elements, or a combination thereof.

[0027] Preferably, the molar ratio of the noble metal to the salt solution is 1:(2-5); more preferably, the molar ratio of the noble metal to the salt solution is 1:(2.5-4.5); and even more preferably, the molar ratio of the noble metal to the salt solution is 1:(3-4.5).

[0028] In the preparation method, the ratio between the salt solution content and the amount of precious metal added needs to be strictly controlled. If the total molar amount of salt solution is greater than 5 times the molar amount of precious metal, more nuclei will form and the nucleation rate will be faster under hydrothermal reaction conditions, resulting in a thinner shell. In some cases, nuclei may not form on the precious metal but on a separate basis. If the total molar amount of salt solution is less than 2 times the molar amount of precious metal, the shell on the precious metal will be incomplete or thin.

[0029] Preferably, the molar ratio of the salt solution to the complexing agent is 1:(1.6-3.2); more preferably, the molar ratio of the salt solution to the complexing agent is 1:(1.7-3); even more preferably, the molar ratio of the salt solution to the complexing agent is 1:(1.8-2.8).

[0030] Preferably, in the preparation method, the salt solution includes a salt solution containing at least one element selected from La, Sr, Mn, Co, Fe, Ni, Y, or Ca; more preferably, in the preparation method, the salt solution includes a salt solution containing at least one element selected from La, Sr, Mn, Co, Fe, Y, or Ca; even more preferably, in the preparation method, the salt solution includes a salt solution containing at least one element selected from La, Sr, Mn, Co, Y, or Ca.

[0031] Preferably, in the preparation method, the salt solution includes at least one of lanthanum nitrate, strontium nitrate, manganese nitrate, cobalt nitrate, ferric nitrate, nickel nitrate, yttrium nitrate, or calcium nitrate; more preferably, in the preparation method, the salt solution includes at least one of lanthanum nitrate, strontium nitrate, manganese nitrate, cobalt nitrate, ferric nitrate, yttrium nitrate, or calcium nitrate; even more preferably, in the preparation method, the salt solution includes at least one of lanthanum nitrate, strontium nitrate, manganese nitrate, cobalt nitrate, yttrium nitrate, or calcium nitrate.

[0032] Preferably, the precious metal is selected from elemental precious metals; more preferably, the elemental precious metal is selected from elemental precious metal particles; even more preferably, the elemental precious metal particles are selected from elemental precious metal nanoparticles.

[0033] Preferably, the particle size of the noble metal nanoparticles is 5-500 nm; more preferably, the particle size of the noble metal nanoparticles is 50-400 nm; and even more preferably, the particle size of the noble metal nanoparticles is 100-300 nm.

[0034] Preferably, in the preparation method, the complexing agent includes citric acid, glycine, or a combination thereof; more preferably, in the preparation method, the complexing agent is selected from citric acid.

[0035] Complexing agents can undergo complexation reactions with metal cations to form complexes, reducing the concentration of free metal cations and avoiding selective precipitation of metal cations during hydrothermal reactions, thereby ensuring the uniformity of the resulting reactants.

[0036] Preferably, in the preparation method, the noble metal, salt solution, and complexing agent are stirred for 1 to 8 hours; more preferably, in the preparation method, the noble metal, salt solution, and complexing agent are stirred for 2 to 6 hours; and even more preferably, in the preparation method, the noble metal, salt solution, and complexing agent are stirred for 3 to 5 hours.

[0037] Preferably, in the preparation method, the hydrothermal reaction time is 20-50 hours; more preferably, in the preparation method, the hydrothermal reaction time is 25-45 hours; and even more preferably, in the preparation method, the hydrothermal reaction time is 30-40 hours.

[0038] In the preparation method, the hydrothermal reaction time is 20-50 hours. If the hydrothermal reaction time is less than 20 hours, a shell will not be formed on the surface of the metal particles or the shell will be too thin and easily break. If the hydrothermal reaction time is more than 50 hours, the shell formed on the surface of the metal particles will be too thick or nucleation and aggregation will occur.

[0039] Preferably, in the preparation method, the temperature of the hydrothermal reaction is 150-250°C; more preferably, in the preparation method, the temperature of the hydrothermal reaction is 160-220°C; and even more preferably, in the preparation method, the temperature of the hydrothermal reaction is 170-200°C.

[0040] In the preparation method, the temperature range of the hydrothermal reaction is 150-250℃. If the temperature is below 150℃, the grain growth is slow and crystallization cannot occur. If the temperature is above 250℃, on the one hand, the grain nucleation rate is too fast, and the resulting grains are uneven, small or even amorphous. On the other hand, as the reaction temperature increases, the danger of the hydrothermal reaction also increases. Therefore, it is necessary to strictly control the temperature of the hydrothermal reaction.

[0041] Preferably, the preparation method further includes a separation step after the hydrothermal reaction yields the precipitate.

[0042] The separation step employs a commonly used separation method. Preferably, the separation includes at least one of centrifugation, filtration, or vacuum filtration; more preferably, the separation is selected from centrifugation.

[0043] Preferably, the preparation method further includes a washing step after the separation step.

[0044] Preferably, in the preparation method, the solution used for washing is a washing liquid, which includes deionized water, an organic solvent, or a combination thereof; more preferably, the washing liquid includes deionized water, anhydrous ethanol, or a combination thereof; even more preferably, the washing liquid is selected from a combination of deionized water and anhydrous ethanol.

[0045] Preferably, the preparation method further includes a drying step after the washing step.

[0046] The third aspect of the present invention provides an application of the cathode material described in the first aspect of the present invention, or the method for preparing the cathode material described in the second aspect of the present invention, in the field of batteries.

[0047] Preferably, the battery is a fuel cell; more preferably, the fuel cell is a solid oxide fuel cell.

[0048] The beneficial effects of this invention are:

[0049] This invention prepares a core-shell structured cathode material by coating a noble metal core with a material having a perovskite structure, spinel structure, or a combination thereof, and making the shell thickness of the core-shell structure proportional to the core particle size, thereby improving the conductivity of the cathode material and ensuring that the thermal expansion properties of the cathode material, electrolyte, and connecting material are matched. Therefore, the cathode material provided by this invention has wide applications in the field of batteries, especially in the field of solid oxide fuel cells. Detailed Implementation

[0050] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described herein are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0051] Examples 1-8

[0052] A cathode is prepared by a method comprising the following steps:

[0053] 1) According to the types and amounts of noble metal nanoparticles recorded in Table 1, the noble metal nanoparticles, 1.4 mol of lanthanum nitrate, 0.6 mol of strontium nitrate, 2 mol of manganese nitrate, and 8 mol of citric acid were stirred to obtain a mixture; wherein, the total amount of salt solution added was 4 mol, and the amount of complexing agent citric acid added was twice the total amount of salt solution added.

[0054] 2) The mixture obtained in step 1) is subjected to a hydrothermal reaction at 185°C for 25 hours to obtain a solution;

[0055] 3) Centrifuge the solution obtained in step 2) to obtain a precipitate;

[0056] 4) The precipitate obtained in step 3) was repeatedly washed with anhydrous ethanol and deionized water and then dried to obtain the cathode materials described in Examples 1 to 8.

[0057] Table 1. Types and amounts of noble metal nanoparticles used in Examples 1-8

[0058]

[0059]

[0060] Examples 9-16

[0061] A cathode is prepared by a method comprising the following steps:

[0062] 1) According to the types and amounts of salt solution, complexing agent, and precious metal nanoparticles recorded in Table 2, the precious metal nanoparticles, complexing agent, and salt solution are stirred to obtain a mixture.

[0063] 2) The mixture obtained in step 1) is subjected to a hydrothermal reaction at 185°C for 25 hours to obtain a solution;

[0064] 3) Centrifuge the solution obtained in step 2) to obtain a precipitate;

[0065] 4) The precipitate obtained in step 3) was repeatedly washed with anhydrous ethanol and deionized water and then dried to obtain the cathode materials described in Examples 9 to 16.

[0066] Table 2 lists the types and amounts of noble metal nanoparticles, salt solutions, and complexing agents used in Examples 9-16.

[0067]

[0068]

[0069] Examples 17-22

[0070] A cathode is prepared by a method comprising the following steps:

[0071] 1) Mix 1 mole of silver nanoparticles, 1.4 moles of lanthanum nitrate, 0.6 moles of strontium nitrate, 2 moles of manganese nitrate, and 8 moles of citric acid to obtain a mixture; wherein the total amount of salt solution added is 4 moles, and the amount of complexing agent citric acid added is twice the total amount of salt solution added.

[0072] 2) According to the heating time and heating temperature recorded in Table 3, the mixture obtained in step 1) is subjected to a hydrothermal reaction to obtain a solution;

[0073] 3) Centrifuge the solution obtained in step 2) to obtain a precipitate;

[0074] 4) The precipitate obtained in step 3) was repeatedly washed with anhydrous ethanol and deionized water and then dried to obtain the cathode materials described in Examples 17 to 22.

[0075] Table 3 Heating time and heating temperature for Examples 17-22

[0076] Example 17 Example 18 Example 19 Example 20 Example 21 Example 22 Cathode material name LSM@Ag LSM@Ag LSM@Ag LSM@Ag LSM@Ag LSM@Ag Heating time / h 20 50 25 25 50 20 Heating temperature / ℃ 185 185 150 250 250 150

[0077] Comparative Examples 1-6

[0078] A cathode is prepared by a method comprising the following steps:

[0079] 1) According to the types and amounts of salt solutions and complexing agents recorded in Table 4, stir the complexing agent and salt solution to obtain a mixture;

[0080] 2) The mixture obtained in step 1) is subjected to a hydrothermal reaction at 185°C for 25 hours to obtain a solution;

[0081] 3) Centrifuge the solution obtained in step 2) to obtain a precipitate;

[0082] 4) The precipitate obtained in step 3) was repeatedly washed with anhydrous ethanol and deionized water and then dried to obtain the cathode materials described in Comparative Examples 1 to 6.

[0083] Table 4 lists the types and amounts of salt solutions and complexing agents used in Comparative Examples 1–6.

[0084]

[0085] Comparative Examples 7–14

[0086] A cathode is prepared by a method comprising the following steps:

[0087] 1) According to the types and amounts of salt solutions and complexing agents recorded in Table 5, 1 molar amount of silver nanoparticles, complexing agents, and salt solutions were stirred to obtain a mixture;

[0088] 2) According to the heating time and heating temperature recorded in Table 5, the mixture obtained in step 1) is subjected to a hydrothermal reaction to obtain a solution;

[0089] 3) Centrifuge the solution obtained in step 2) to obtain a precipitate;

[0090] 4) The precipitate obtained in step 3) was repeatedly washed with anhydrous ethanol and deionized water and then dried to obtain the cathode materials described in Comparative Examples 7 to 14.

[0091] Table 5 lists the types and amounts of salt solutions used in Comparative Examples 7–14, the types and amounts of complexing agents used, and the heating time and temperature.

[0092]

[0093] Performance testing

[0094] The cathode materials of Examples 1-22 and Comparative Examples 1-14 were tested as follows:

[0095] 1) Shell thickness to core diameter ratio: The cathode material was cut along the diameter using FIB instruments. The shell thickness d1 and core diameter d2 were observed and measured under TEM, and the ratio of shell thickness to core diameter d1 / d2 was calculated.

[0096] 2) Nuclear mass ratio: The nuclear mass ratio M1 / M2×100% was calculated by analyzing the mass M1 of the noble metal nanoparticles and the mass M2 of the cathode material prepared by the reaction using an analytical balance.

[0097] 3) Coefficient of thermal expansion (CTE): Thermal expansion was tested using a high-temperature thermal expansion apparatus, with a temperature range of 100–1000℃ and a heating rate of 10 K·min. -1 Because fuel cell materials have different coefficients of thermal expansion, it is essential to ensure that the thermal expansion properties of the electrode materials, electrolyte, and connecting materials are matched within the fuel cell's operating temperature range. Generally, the coefficients of thermal expansion for electrolyte and connecting materials are (10–17) × 10⁻⁶. -6 K -1 The thermal expansion coefficient of the cathode material in this application meets the following requirements: (10~17)×10 -6 K -1 .

[0098] 4) Conductivity: The cathode is prepared by sintering the cathode material described in this invention at 900–1450°C for 2–5 hours. The conductivity of the cathode at 800°C is measured using a DC four-probe method with a digital source meter. The cathode conductivity requirement of this application is greater than 600 S / cm.

[0099] 5) Proportion of irregular or amorphous particles: The proportion of irregular or amorphous particles within a 50μm × 50μm area observed under a 50K magnification electron microscope. An excessively high proportion of particles with non-uniform morphology will prevent the existing sintering process from producing a high-quality cathode. The resulting cathode powder will have uneven porosity, leading to reduced catalytic performance and decreased fuel cell durability. More seriously, poor cathode quality will increase fuel cell losses related to polarization and ohmic losses, thus reducing fuel cell efficiency. The requirement for the proportion of irregular or amorphous particles in the cathode material of this application is: less than 10% within a 50μm × 50μm area.

[0100] The test results are recorded in Table 6.

[0101] Table 6. Test results of cathode material performance in Examples 1-22 and Comparative Examples 1-14

[0102]

[0103]

[0104] As can be seen from the above embodiments and comparative examples, the present invention prepares a core-shell structured cathode material by using a material having a perovskite structure, spinel structure or a combination thereof to coat a noble metal core, and making the shell thickness of the core-shell structure in a certain proportion to the core particle size, thereby improving the conductivity of the cathode material and ensuring that the thermal expansion properties of the cathode material are matched with those of the electrolyte and connecting materials. Therefore, the cathode material provided by the present invention has wide applications in the field of batteries, especially in the field of solid oxide fuel cells.

Claims

1. A cathode material, characterized in that, The cathode material has a core-shell structure, wherein the core contains a noble metal, and the shell comprises a perovskite structure, a spinel structure, or a combination thereof; the shell covers the surface of the core; the ratio of the shell thickness to the core diameter is 1 to 10; the noble metal includes at least one of gold, silver, platinum, ruthenium, rhodium, palladium, osmium, or iridium; the perovskite structure includes at least one of LSM, LSCF, LSF, or LNF; the spinel structure includes MnCo2O4, CoMn2O4, CoFe2O4, Co3O4, NiFe2O4, CuFe2O4, Mn... 1.5 Co 1.5 O4, MnCo 2-x Fe x O4 or LiMn 2-x M x At least one of O4, wherein M includes at least one of Ni, Mg, Cu, Co, Zn, Cr, Fe, and Zr, 0 <x<1。 2. Cathode material according to claim 1, characterized in that The core accounts for 5-95% of the mass fraction of the cathode material.

3. The cathode material of claim 1, wherein, The particle size of the core is 5-500 nm. And / or, the thickness of the shell is 5-5000 nm.

4. The method of producing a cathode material according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: The noble metal, the salt solution and the complexing agent are stirred to obtain a mixture, and the mixture is subjected to a hydrothermal reaction to obtain the cathode material; the salt solution comprises a salt solution containing rare earth elements, a salt solution containing transition metal elements or a combination thereof.

5. The preparation method according to claim 4, characterized in that, The molar ratio of the noble metal to the salt solution is 1:(2-5); And / or, the molar ratio of the salt solution to the complexing agent is 1:(1.6-3.2).

6. The preparation method according to claim 4, characterized in that, The salt solution comprises a salt solution containing at least one element selected from La, Sr, Mn, Co, Fe, Ni, Y and Ca; And / or, the complexing agent comprises citric acid, glycine or a combination thereof.

7. The preparation method according to claim 4, characterized in that, The hydrothermal reaction is performed for 20-50 h. And / or, the hydrothermal reaction is performed at a temperature of 150-250 ℃.

8. Use of a cathode material or a method for producing a cathode material in the field of batteries, characterized in that The cathode material is the cathode material according to any one of claims 1-3, and the preparation method of the cathode material is the preparation method of the cathode material according to any one of claims 4-7.

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