A-site defect regulated high-entropy cobalt-based double perovskite solid oxide cathode material, and preparation method and application thereof

Abstract

The application belongs to the technical field of solid oxide fuel cell cathode materials, and discloses a kind of A site defect regulated high-entropy cobalt-based double perovskite solid oxide cathode material and its preparation method and application.The cathode material is composed of the A site defect derivative of the basic high-entropy cobalt-based double perovskite;The A site defect derivative is (Gd 1 / 6 Pr 1 / 6 La 1 / 6 Ba 1 / 6 Sr 1 / 6 Ca 1 / 6 ) 0.93 CoO3.The application solves the contradiction between activity, stability and process adaptability of existing cathode materials through the synergistic strategy of "high-entropy structure design + A site defect engineering", and can be applied to related electrocatalysis fields such as electrocatalytic oxygen evolution and carbon dioxide reduction.

Description

Technical Field

[0001] This invention relates to the field of cathode materials technology for solid oxide fuel cells (SOFCs), and more specifically to a low-to-medium temperature adaptable A-site defect-regulated high-entropy cobalt-based double perovskite solid oxide fuel cell cathode material, its preparation method, and its application. Background Technology

[0002] SOFC, as a highly efficient and green energy conversion device, possesses core advantages such as high energy conversion efficiency, wide fuel adaptability, and environmental friendliness, making it one of the key technologies for addressing the global energy crisis and environmental pollution. The core of the electrochemical reaction in SOFC is concentrated at the three-phase interface of the cathode, anode, and electrolyte. Among these, the ORR (Organic Reaction Rate) of the cathode, due to its high activation energy and slow reaction kinetics, has become a core bottleneck restricting the overall performance improvement of the battery. Therefore, developing high-performance cathode materials suitable for medium and low temperature operation is a key breakthrough for promoting the practical application of SOFC.

[0003] Perovskite oxides (ABO3) are the mainstream research system for SOFC cathodes. To overcome the performance limitations of traditional perovskites, the research community has gradually formed a multi-dimensional optimization path: traditional low-entropy perovskites such as La... 1-x Sr x MnO 3-δ (LSM) exhibits excellent stability but lacks sufficient catalytic activity; mixed ion-electron conductors such as La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ While LSCF (La-doped low-entropy perovskite cathode) exhibits improved catalytic activity, its thermal expansion coefficient and electrolyte compatibility are poor. To address this contradiction, targeted explorations have been conducted in related technologies: CN200810055747.1 discloses a La-doped low-entropy perovskite cathode material (Ba... 0.5 Sr 0.5 ) 1-x La x Co 0.8 Fe 0.2 O 3-δ The conductivity is improved by dual-element doping at the A site, but the multi-element synergistic effect is limited in low-entropy systems and defect regulation is not involved; CN114744222A proposes a dual perovskite material (Ba) with A-site ratio regulation. 1-x Gd 0.8 Pr 0.2+x Co2O 6-δ While optimizing low- and medium-temperature stability, it still belongs to a low-entropy structure, and oxygen vacancy regulation relies on adjusting the proportion of a single element, resulting in insufficient flexibility; CN119191372A designed a recyclable cathode material (Ba) of single / double perovskite composites. 1.1 (Gd 0.8 La0.2 ) 0.9 (Co 1.5 Fe 0.5 )O 6-δ The study focused on material recyclability but neglected in-depth optimization of ORR activity.

[0004] In recent years, high-entropy perovskite oxides have exhibited unique advantages due to the disordered and uniform distribution of various cations at the A / B sites. The synergistic effect of multiple elements can flexibly control lattice distortion, electronic structure, and oxygen vacancy concentration, while significantly improving the thermal stability and chemical compatibility of the material, making it an important research direction for SOFC cathode materials. At the same time, A-site defect engineering, as a classic performance regulation strategy, has been proven to induce oxygen vacancy formation through cation deletion, thereby improving oxygen ion conductivity and surface oxygen exchange capacity (such as the A-site defect-containing medium-entropy perovskite disclosed in CN117737767A, which verified the effect of defects on activity enhancement, but its core application is in the oxygen evolution reaction (OER) of water electrolysis, where the medium-entropy system cannot leverage the containment and stabilization effect of the high-entropy structure on defects).

[0005] However, existing technologies have not yet achieved an effective integration of "high-entropy structures" and "defect engineering": although patents such as CN201810459689 and CN202510530878 involve A-site regulation, they focus on non-SOFC scenarios such as NO catalytic oxidation and toluene catalytic oxidation, and the low-entropy double perovskite structure does not match the requirements of medium and low temperature ORR; most high-entropy perovskite studies only focus on structural stability and do not introduce defect engineering to optimize oxygen vacancy concentration; and technologies involving defects are mostly limited to medium and low-entropy systems, and the introduction of defects can easily lead to problems such as cation aggregation and phase separation.

[0006] Currently, the existing technology has the following problems:

[0007] 1. Lack of synergistic regulation between high entropy and defects makes it difficult to simultaneously achieve both activity and stability: Existing technologies are either limited to elemental doping in low-entropy systems, resulting in limited multi-element synergistic effects and an inability to optimize active sites through lattice distortion depth; or they focus solely on the stability of high-entropy structures or defect regulation in medium- and low-entropy systems, failing to achieve synergy between the two. Introducing defects into medium- and low-entropy systems easily leads to cation aggregation, while the lack of defect regulation in high-entropy systems results in insufficient oxygen vacancy concentration. Neither approach can simultaneously meet the dual requirements of activity and stability for low- and medium-temperature ORR.

[0008] 2. The contradiction between low-temperature performance and the compatibility of the preparation process is prominent: Existing low-entropy cathode materials require high-temperature sintering above 1100℃ and long-time sintering of more than 10 hours to ensure crystallinity and stability, resulting in excessive energy consumption and easy reaction with the electrolyte interface; although some double perovskite materials have reduced the sintering temperature to 900~1000℃, the low-entropy structure limits the improvement of low-temperature activity; perovskite materials in non-SOFC scenarios are calcined at only 600℃, resulting in insufficient crystallinity and inability to withstand the low-temperature operating environment of SOFC. In contrast, this invention uses sintering conditions of 1000℃ and 5 hours, which solves the crystallinity problem of low-temperature calcination and avoids the contradiction between energy consumption and interface compatibility of high-temperature long-time sintering. Existing technologies have not yet formed an optimized solution that balances process economy and low-temperature performance.

[0009] 3. Insufficient structural tunability and scenario adaptability: The number of A-site elements in existing SOFC cathode materials is generally ≤4, belonging to low-entropy / medium-entropy systems, with limited structural tunability, making it difficult to flexibly control lattice parameters and electronic structure through multi-element synergy; moreover, the design goal of some materials is not medium- and low-temperature ORR, and their structure and process have not been optimized for the medium- and low-temperature operation requirements of SOFC, resulting in the oxygen vacancy concentration and number of active sites of the material not being able to accurately match the ORR kinetic requirements, and the scenario adaptability is significantly insufficient.

[0010] This technological gap has resulted in the ORR activity of high-entropy perovskites not being fully released. There is still considerable room for optimization in polarization resistance, power density, and long-term stability in the mid-to-low temperature range. There is an urgent need to develop a synergistic innovative SOFC cathode material that combines "stability provided by high-entropy structure with activity optimized by defect engineering". Summary of the Invention

[0011] In view of this, the present invention provides a high-entropy cobalt-based double perovskite solid oxide cathode material with A-site defect regulation, its preparation method and application.

[0012] This invention focuses on optimizing the activity of oxygen reduction reaction (ORR) in SOFC at medium and low temperatures (500~700℃). Through a synergistic strategy of "high-entropy structural design + A-site defect engineering", it solves the contradiction between the activity, stability and process adaptability of existing cathode materials. At the same time, it can be extended to related electrocatalytic fields such as electrocatalytic oxygen evolution and carbon dioxide reduction.

[0013] One objective of this invention is to provide a high-entropy cobalt-based double perovskite solid oxide cathode material with A-site defect modulation, composed of A-site defect-type derivatives of a basic high-entropy cobalt-based double perovskite; wherein,

[0014] The basic high-entropy cobalt-based double perovskite (GPLBSC) CO: A site is composed of six rare earth / alkaline earth metals, Gd, Pr, La, Ba, Sr and Ca, in equimolar ratio (entropy value ≥1.5R, typical hexa-element high-entropy perovskite system), B site is Co element, the whole is a single-phase cubic perovskite structure, no impurity phase is formed;

[0015] Preferably, the B site is a single Co active center.

[0016] The A-site defective derivative (GPLBSC) 0.93 CO: Introduces 7% A-site cation defects into the basic high-entropy cobalt-based double perovskite structure. The defects induce lattice expansion, while significantly increasing the oxygen vacancy concentration through charge compensation, without destroying the cubic perovskite host structure.

[0017] Preferably, the basic high-entropy cobalt-based perovskite has the general chemical formula (Gd... 1 / 6 Pr 1 / 6 La 1 / 6 Ba 1 / 6 Sr 1 / 6 Ca 1 / 6 CoO3, the general chemical formula of the A-site defective derivative is (Gd) 1 / 6 Pr 1 / 6 La 1 / 6 Ba 1 / 6 Sr 1 / 6 Ca 1 / 6 ) 0.93 CoO3.

[0018] The second objective of this invention is to provide a method for preparing a high-entropy cobalt-based double perovskite solid oxide cathode material with A-site defect modulation, the specific steps of which are as follows:

[0019] (1) According to (Gd) 1 / 6 Pr 1 / 6 La 1 / 6 Ba 1 / 6 Sr 1 / 6 Ca 1 / 6 ) 0.93 The stoichiometry of CoO3, weighing Gd2O3 and Pr6O 11 La2O3, BaCO3, SrCO3, CaCO3 and Co(NO3)2·6H2O, for later use;

[0020] (2) Dissolve Gd2O3 in a 1.3-1.4 mol / L dilute nitric acid solution, and then add Pr6O4 sequentially. 11La2O3, BaCO3, SrCO3, CaCO3 and Co(NO3)2·6H2O were mixed and then a complexing agent was added. The mixture was heated and stirred, then cooled and the pH was adjusted to 7-8. After stirring, the temperature was raised to evaporate the water to obtain a gel.

[0021] (3) The gel is heated and dried to obtain cathode precursor powder;

[0022] (4) Sinter the cathode precursor powder to obtain the cathode material (Gd). 1 / 6 Pr 1 / 6 La 1 / 6 Ba 1 / 6 Sr 1 / 6 Ca 1 / 6 ) 0.93 CoO3, denoted as (GPLBSC) 0.93 CO.

[0023] The core process of the above technical solution is the preparation of the target powder using the sol-gel method;

[0024] The core of the above technical solution is to suppress the cationic agglomeration that may be caused by defects by using the steric hindrance effect of the multi-element system in the high-entropy system, so as to ensure that the powder has a single-phase structure and uniform element distribution.

[0025] Preferably, in step (2), the complexing agent is citric acid and ethylenediaminetetraacetic acid.

[0026] Preferably, the citric acid is 1.5 times the total molar amount of metal ions, and the ethylenediaminetetraacetic acid is 0.5 times the total molar amount of metal ions.

[0027] Preferably, in step (2), the temperature is cooled to 90°C after heating and stirring for 15 minutes and then cooled to 40°C; the stirring time is 4 hours.

[0028] Preferably, in step (4), the sintering is performed at 1000°C for 5 hours.

[0029] The third objective of this invention is to provide an application of a high-entropy cobalt-based double perovskite solid oxide cathode material regulated by A-site defects, which is used as a SOFC cathode; or as an electrocatalytic material applied to oxygen reduction / oxygen evolution reactions in metal-air batteries and water electrolyzers, as well as in the electrocatalytic fields of carbon dioxide electroreduction and nitrogen reduction.

[0030] Preferably, the use of the A-site defect-controlled high-entropy cobalt-based double perovskite solid oxide material in the SOFC cathode specifically refers to its use in symmetrical cells or anode-supported single cells.

[0031] More preferably, the symmetrical battery adopts (GPLBSC). 0.93 CO|BZCYYb1711|(GPLBSC) 0.93 The CO layered structure was used. The electrolyte substrate was BZCYYb1711 (15 mm in diameter and approximately 1 mm thick). The cathode paste was prepared with a mass ratio of cathode powder: terpineol: ethyl cellulose = 1:0.93:0.07. After coating, it was sintered at 1000℃ for 3 hours, resulting in a cathode active area of ​​0.2 cm². 2 The surface is coated with Ag paste as a current collector for electrochemical impedance spectroscopy.

[0032] More preferably, the anode-supported single cell employs a NiO-BZCYYb1711 support | functional layer | BZCYYb1711 electrolyte | (GPLBSC) 0.93 CO cathode structure. The anode support and electrolyte are prepared by dry pressing and tape casting co-sintering. After the cathode slurry is coated, it is sintered at 1000℃ for 3 hours to ensure a tight bond between the cathode and electrolyte interface without cracks or detachment.

[0033] As can be seen from the above technical solution, compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0034] I. Technical problems to be solved:

[0035] 1. It solves the problem that traditional SOFC perovskite cathodes cannot simultaneously achieve catalytic activity, stability and interfacial compatibility, as well as the core problem of insufficient oxygen vacancy concentration and slow ORR kinetics when high-entropy perovskites are not combined with A-site defect engineering.

[0036] 2. This solves the problem of high cathode polarization resistance in traditional SOFCs, which leads to low power density and poor electrochemical performance at medium and low temperatures in single cells;

[0037] 3. It solves the technical bottleneck of traditional SOFC electrolyte layer preparation processes (single dry pressing, casting or sintering) that make it difficult to achieve "ultra-thin + dense + strong interlayer bonding" - the electrolyte layer prepared by existing processes is generally ≥20μm thick, resulting in a high proportion of ohmic loss; or the interlayer bonding is loose and prone to cracking, which leads to an increase in interfacial impedance and seriously restricts the battery output efficiency.

[0038] 4. It fills the technological gap of the synergistic design of "high-entropy defect cathode + ultra-thin electrolyte layer" - existing technologies have not combined cathode material innovation with device fabrication process innovation, and cannot give full play to the 1+1>2 effect of "active cathode + low-resistance device", which makes it difficult for battery performance to break through the existing upper limit.

[0039] II. Advantages

[0040] 1. Compared to single high-entropy cathodes (defect-free) and medium-to-low-entropy defect cathodes, this invention, through the synergistic effect of "six-element high-entropy A-site + 7% precise defects," reduces the ORR activation energy from 1.39 eV to 1.28 eV, and the polarization resistance at 700℃ is as low as 0.18 Ω·cm. 2 It reduces entropy by 35.7% compared to a single high-entropy cathode and by more than 50% compared to a traditional LSCF cathode.

[0041] 2. An innovative "casting + co-pressing + one-step co-sintering" process was employed to successfully fabricate a dense BZCYYb1711 electrolyte layer with a thickness of only 8 μm (compared to 20-50 μm for electrolyte layers produced using traditional methods), making it over 50% thinner than existing technologies; furthermore, the electrolyte layer is tightly bonded to the anode functional layer and cathode layer (see attached diagram). Figure 4 (Single cell structural schematic diagram and cross-sectional SEM evidence), no cracks or interface peeling. This design reduces ohmic loss by more than 30%, significantly reducing energy loss—when paired with a high-entropy defect cathode, the maximum power density of the anode-supported single cell reaches 1.91 W·cm³ at 700℃. -2 It achieves a 40% improvement over the traditional structure using a 20μm thick electrolyte and a 66.95% improvement over the high-entropy cathode + conventional electrolyte structure without introducing defects, realizing the synergistic effect of "active cathode + low-resistance device".

[0042] 3. Excellent cathode-electrolyte synergy and superior performance at medium and low temperatures.

[0043] The thermal expansion coefficient of the high-entropy defect cathode of this invention, after defect modulation, further improves its matching degree with the ultrathin BZCYYb1711 electrolyte (thermal expansion coefficient difference ≤ 1.5 × 10⁻⁶). -6 K -1 This design avoids interfacial cracks caused by thermal stress during high-temperature sintering or long-term operation. Simultaneously, the ultra-thin electrolyte layer shortens the oxygen ion transport path, forming a "transport-activity" synergy with the abundant oxygen vacancies in the cathode. This significantly reduces the performance degradation of the battery in the medium-low temperature range (500~650℃)—the power density still reaches 0.66 W·cm³ at 600℃. 2 Compared with the traditional structure, it improves by 127.6%, solves the industry pain point of "cliff-like drop" in the performance of existing SOFCs in the low temperature range, and expands the practical temperature range of SOFCs.

[0044] 4. It combines technological innovation with industrialization potential, and has significant advantages in cost and efficiency.

[0045] The co-pressing-co-sintering process employed in this invention eliminates the need for complex multi-step sintering or interface modification, achieving a dense composite of "anode support-functional layer-electrolyte" in a single step. This process increases production efficiency by 50% and reduces energy consumption by 25% compared to traditional processes. The 8μm ultrathin electrolyte layer reduces electrolyte raw material usage by 60%, and combined with the non-precious metal composition of the high-entropy defect cathode (free of precious metals such as Ir and Ru), it reduces costs by more than 40% compared to cathode materials containing precious metals. Furthermore, this process can be scaled up (compatible with industrial-grade casting machines and sintering furnaces), and the batch-to-batch uniformity of cathode powder prepared by the sol-gel method is ≥95%. It is compatible with industrial-grade device fabrication processes such as screen printing and coating, solving the bottlenecks of existing high-performance SOFCs characterized by "complex processes, high costs, and difficulty in mass production." This provides core support for the large-scale promotion of SOFCs and the goal of zero carbon dioxide emissions.

[0046] 5. High structural adjustability, enabling wider application scenarios.

[0047] This invention can be adapted to different electrolyte systems (CGO, YSZ, etc.) and operating temperature requirements by adjusting the A-site defect amount (5%~10%), A-site elemental composition, and B-site doping (Fe, Mn, etc.). At the same time, the synergistic design of "high-entropy defect cathode + ultra-thin device" is not only applicable to SOFC, but can also be extended to reversible solid oxide batteries (Re-SOC), metal-air batteries and other fields. It exhibits excellent performance in both oxygen reduction / oxygen evolution reactions, and is more competitive in application scenarios than single-function catalysts.

[0048] 6. Simple preparation and assembly process: The cathode powder is prepared by the sol-gel method, which is easy to operate, highly controllable, and suitable for large-scale industrial production; the battery device assembly process is simple, the cathode material and electrolyte layer are tightly bonded, there are no interface cracks, and the interface compatibility is good. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0050] Figure 1 It is (GPLBSC)CO and (GPLBSC) 0.93 X-ray diffraction (XRD) pattern of CO;

[0051] Figure 2 Yes (GPLBSC) 0.93Microscopic images of CO obtained by field emission transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy (EDS) distribution maps of gadolinium, praseodymium, lanthanum, barium, strontium, calcium, cobalt, and oxygen.

[0052] Figure 3 Yes (GPLBSC) 0.93 High-resolution transmission electron microscopy (HRTEM) images of CO grains;

[0053] Figure 4 It is based on (GPLBSC) 0.93 Scanning electron microscope image of the surface of a CO electrolyte-supported symmetrical cell;

[0054] Figure 5 It is based on (GPLBSC) 0.93 Cross-sectional image of a Ni-BZCYYb anode-supported single cell of CO;

[0055] Figure 6 This refers to the polarization resistance of the (GPLBSC) CO cathode at different temperatures.

[0056] Figure 7 Yes (GPLBSC) 0.93 Polarization resistance of CO cathode at different temperatures;

[0057] Figure 8 It is (GPLBSC)CO and (GPLBSC) 0.93 graph showing the relationship between the conductivity of CO and temperature.

[0058] Figure 9 This is the current-voltage-power (IVP) curve of a (GPLBSC) CO single cell;

[0059] Figure 10 Yes (GPLBSC) 0.93 Current-voltage-power (IVP) curve of CO single cell. Detailed Implementation

[0060] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0061] This invention proposes a low-to-medium temperature adaptable A-site defect-controlled high-entropy cobalt-based double perovskite solid oxide fuel cell cathode material based on the synergistic design of "six-element high-entropy A-site + 7% precise defects", which can be used in the following scenarios:

[0062] 1. Core cathode materials for medium- and low-temperature SOFCs: Solving the problem of imbalance between activity and stability

[0063] As a core cathode material for medium- and low-temperature (500~700℃) solid oxide fuel cells, this material addresses the core pain points of insufficient catalytic activity at low temperatures and easy degradation during long-term operation through a synergistic design of "high-entropy structure + precise defects at A-sites". The synergistic effect of its hexa-membered high-entropy A-sites and 7% defects can significantly reduce polarization resistance (down to 0.18 Ω·cm). 2 ), and increased power density (up to 1.91 W·cm³). -2 Furthermore, it exhibits no significant degradation during continuous operation at 600℃, achieving a simultaneous breakthrough in activity and stability within the medium and low temperature range.

[0064] 2. Multi-scenario electrocatalytic materials: breaking through the limitations of single function

[0065] Leveraging the electronic regulation advantages of high-entropy systems and the abundance of defect-induced active sites, this technology can adapt to various electrocatalytic reactions such as oxygen evolution, carbon dioxide electroreduction, and nitrogen reduction without requiring core structure reconstruction, simply by fine-tuning the amount of defects at A sites or the elemental ratio. It directly addresses the pain points of traditional catalysts—"single function, limited application scenarios"—by providing a non-precious metal-based universal material solution that balances reaction efficiency and long-term stability.

[0066] 3. Industrial-grade compatible materials: Solving compatibility and mass production bottlenecks

[0067] Precisely matching industrialization needs, it is compatible with mainstream SOFC electrolyte systems, overcoming the limitation of traditional materials that are "suitable for a single electrolyte in a single system." The optimized sol-gel preparation process parameters are controllable, the catalyst preparation method is simple, and the stability is good, making it promising for industrial production. Moreover, it has lower energy consumption and is compatible with industrial-grade device fabrication processes, directly addressing the industrialization pain points of "poor compatibility and high difficulty in mass production," providing practical support for the large-scale promotion of SOFC.

[0068] The present invention will now be described in detail.

[0069] The technical solution of this invention is divided into three parts: preparation of high-entropy cobalt-based double perovskite cathode material, assembly of SOFC battery device, and performance regulation of materials and devices. The technical solution is as follows:

[0070] Example 1

[0071] 1. Composition and structure of cathode materials:

[0072] A-site defective derivatives (Gd 1 / 6 Pr 1 / 6 La 1 / 6 Ba 1 / 6 Sr 1 / 6 Ca 1 / 6 )0.93 CoO3), abbreviated as (GPLBSC) 0.93 CO. (GPLBSC) 0.93 CO has a single-phase cubic perovskite structure, with the A-site composed of six equimolar rare earth / alkaline earth metals: Gd, Pr, La, Ba, Sr, and Ca, and the B-site being Co. (GPLBSC) 0.93 CO is an A-site defect modified product of (GPLBSC)CO, with a 7% loss of A-site cations, which causes lattice expansion, increases cell parameters, and significantly increases oxygen vacancy concentration compared to (GPLBSC)CO.

[0073] Performance regulation design of the present invention

[0074] Structure-activity synergy: The 7% defect at site A induces lattice contraction, altering the coordination environment of the Co active center at site B and exposing more low-coordination active sites. Simultaneously, the electronic synergistic effect of the high-entropy system optimizes the valence distribution of Co. Defect-transport synergy: The absence of cations at site A leads to insufficient positive charge in the system, resulting in oxygen vacancies through lattice oxygen removal. O) performs charge compensation, which significantly improves oxygen ion conductivity and surface oxygen exchange rate, accelerating key elementary reactions of ORR.

[0075] 2. Preparation method:

[0076] (1) According to the catalyst material (Gd 1 / 6 Pr 1 / 6 La 1 / 6 Ba 1 / 6 Sr 1 / 6 Ca 1 / 6 ) 0.93 The stoichiometry of CoO3, and the accurate weighing of Gd2O3 and Pr6O 11 La2O3, BaCO3, SrCO3, CaCO3 and Co(NO3)2·6H2O, for later use;

[0077] (2) Dissolve Gd2O3 in a 1.3-1.4 mol / L dilute nitric acid solution, and then add Pr6O4 sequentially. 11 La2O3, BaCO3, SrCO3, CaCO3 and Co(NO3)2·6H2O were mixed and then citric acid and ethylenediaminetetraacetic acid were added as complexing agents. The mixed solution was heated and stirred at 90℃ for 15 minutes, then cooled to 40℃ and the pH was adjusted to 7~8. After stirring slowly for 4 hours, the temperature was raised to 120℃ to evaporate the water and obtain a gel.

[0078] Citric acid is 1.5 times the total number of moles of metal ions, and ethylenediaminetetraacetic acid is 0.5 times the total number of moles of metal ions.

[0079] (3) The gel obtained in step (2) was placed in an oven and heated at 250°C for 4 hours to obtain a fluffy cathode precursor powder;

[0080] (4) The precursor powder obtained in step (3) is placed in a muffle furnace and sintered at 1000℃ for 5 hours to obtain the A-site cation defect double perovskite catalyst (Gd). 1 / 6 Pr 1 / 6 La 1 / 6 Ba 1 / 6 Sr 1 / 6 Ca 1 / 6 ) 0.93 CoO3.

[0081] Comparative Example 1

[0082] 1. Composition and structure of cathode materials:

[0083] Basic high-entropy cobalt-based double perovskite (Gd 1 / 6 Pr 1 / 6 La 1 / 6 Ba 1 / 6 Sr 1 / 6 Ca 1 / 6 )CoO3), abbreviated as (GPLBSC)CO.

[0084] 2. Preparation method:

[0085] (1) According to the catalyst material (Gd 1 / 6 Pr 1 / 6 La 1 / 6 Ba 1 / 6 Sr 1 / 6 Ca 1 / 6 The stoichiometric ratio of CoO3, and the accurate weighing of Gd2O3 and Pr6O 11 La2O3, BaCO3, SrCO3, CaCO3 and Co(NO3)2·6H2O, for later use;

[0086] (2) Dissolve Gd2O3 in a 1.3-1.4 mol / L dilute nitric acid solution, and then add Pr6O4 sequentially. 11 La2O3, BaCO3, SrCO3, CaCO3 and Co(NO3)2·6H2O were mixed and then citric acid and ethylenediaminetetraacetic acid were added as complexing agents. The mixed solution was heated and stirred at 90℃ for 15 minutes, then cooled to 40℃ and the pH was adjusted to 7~8. After stirring slowly for 4 hours, the temperature was raised to 120℃ to evaporate the water and obtain a gel.

[0087] Citric acid is 1.5 times the total number of moles of metal ions, and ethylenediaminetetraacetic acid is 0.5 times the total number of moles of metal ions.

[0088] (3) The gel obtained in step (2) was placed in an oven and heated at 250°C for 4 hours to obtain a fluffy cathode precursor powder;

[0089] (4) The precursor powder obtained in step (3) is placed in a muffle furnace and sintered at 1000℃ for 5h to obtain catalyst powder (Gd). 1 / 6 Pr 1 / 6 La 1 / 6 Ba 1 / 6 Sr 1 / 6 Ca 1 / 6 )CoO3.

[0090] Appendix Figure 1 The XRD patterns of Example 1 and Comparative Example 1 confirm that both are single-phase cubic perovskite structures (GPLBSC). 0.93 The main CO diffraction peak has shifted at a low angle, indicating lattice expansion. (See attached image.) Figure 2 The TEM images also confirmed the increase in lattice spacing. Figure 3 The elements are evenly distributed and there is no aggregation. This together proves (GPLBSC). 0.93 Successful synthesis of CO cathode material.

[0091] It is worth noting that the double perovskite cathode material obtained by controlling A-site cation defects involved in this invention is prepared by the sol-gel method, achieving precise synergistic optimization of the three core properties of "activity-ion transport-stability". This fundamentally breaks through the core bottleneck of existing double perovskites where "performance is compromised in one aspect" - without relying on multiphase composites, it can achieve lower polarization resistance, lower activation energy, higher power density and good stability by controlling A-site selective defects in a single double perovskite phase.

[0092] Application examples

[0093] Battery device structure design:

[0094] Design two SOFC devices based on this cathode material. The symmetrical cell adopts a "cathode|electrolyte|cathode" structure, specifically including the following steps:

[0095] 1) Weigh 2g of cathode powder, and grind 1g of cathode powder, 0.93g of terpineol and 0.07g of ethyl cellulose in a mortar and grind them to make cathode slurry according to the mass ratio of cathode powder: terpineol: ethyl cellulose = 1:0.93:0.07.

[0096] 2) Apply the cathode paste evenly to the dense BZCYYb1711 (BaZr) substrate by brushing. 0.1 Ce 0.7 Y 0.1 Yb 0.1The electrolyte sheet was calcined at 1000°C for 3 hours in air to produce (GPLBSC)CO and (GPLBSC) respectively. 0.93 The CO porous electrode has an effective cathode area of ​​0.2 cm². 2 Symmetrical cells (GPLBSC) were obtained. 0.93 Symmetrical cells of CO, such as Figure 4 This method is used to test the polarization impedance of cathode materials in the temperature range of 500-700℃. The symmetrical cell using (GPLBSC)CO as the cathode has a polarization impedance of 0.153 Ωcm at 700℃. -2 ; with (GPLBSC) 0.93 A symmetrical cell with CO as the cathode has a polarization impedance of 0.064 Ωcm at 700 °C. -2 As attached Figure 6 , attached Figure 7 The polarization resistance test shows that (GPLBSC) 0.93 The polarization resistance of the CO cathode at 700℃ is 58.17% lower than that of (GPLBSC)CO.

[0097] Figure 8 For (GPLBSC)CO and (GPLBSC) 0.93 The conductivity of CO was measured at 25°C intervals within the temperature range of 300-800°C in air. As can be seen from the figure (GPLBSC)... 0.93 The electrical conductivity of CO decreases with increasing temperature in the range of 500-700℃, exhibiting characteristics similar to other cobalt-based high-entropy perovskite materials. Although its conductivity at low temperatures is slightly lower than that of (GPLBSC)CO, its conductivity is within the range of 1400-1700 S·cm. -1 Between these parameters, the basic requirements for SOFC cathodes are still met.

[0098] The anode-supported single cell was fabricated using porous 65NiO-35BZCYYb1711 as the substrate, 65NiO-35BZCYYb1711 (containing no starch) as the functional layer (AFL), and BZCYYb1711 as the electrolyte membrane. The anode-supported half-cell was prepared using dry pressing, casting, and co-sintering techniques. Figure 5The specific steps are as follows: The dry-pressed anolyte preform is used as a support substrate and co-pressed with the cast double-layer tape (electrolyte / functional layer), followed by a one-step high-temperature co-sintering. To prepare the double-layer tape containing the electrolyte and functional layer, BZCYYb1711 electrolyte powder and functional layer powder are mixed with dispersants (ethanol, methyl ethyl ketone, and triethanolamine TEA) at a mass ratio of 100:10:1, and ball-milled for 12 hours to achieve uniform dispersion. Subsequently, 8% by mass of binder (polyvinyl butyral, PVB) and 5% by mass of plasticizer (a mixture of dibutyl phthalate (DBP) and polyethylene glycol PEG-400 at a mass ratio of 2:1) are added to their respective slurries, followed by another 8-hour ball milling process to finally obtain an electrolyte and functional layer slurry with suitable viscosity suitable for cast molding. Using a casting machine, the electrolyte slurry is first cast onto a polyethylene terephthalate (PET) carrier film, controlling the wet tape thickness to achieve a dried electrolyte layer thickness of approximately 8 μm. Next, the functional layer slurry is cast onto its surface, resulting in a dried functional layer thickness of approximately 15 μm. Finally, the resulting bilayer tape is dried at room temperature for at least 24 hours to remove residual solvent. 0.35 g of anode support powder is weighed and dry-pressed in a mold at 20 MPa pressure into a blank with a diameter of 18 mm and a thickness of 1 mm. Simultaneously, the dried bilayer tape is punched into a 15 mm diameter disc using a punch. This disc is placed on top of the anode blank and co-pressed in a mold at 15 MPa pressure to tightly bond the three layers (anode / functional layer / electrolyte), forming a complete battery blank. The battery blank is then placed in a high-temperature furnace and sintered at 1480 °C for 5 hours at a heating rate of 3 °C / min and a cooling rate of 3 °C / min to achieve densification, resulting in a half-cell with a robust electrolyte layer. After the half-cell has cooled to room temperature, the cathode paste is evenly coated onto the surface of the sintered electrolyte layer using a brush, controlling the electrode area to be 0.2 cm². 2 Finally, the cells were sintered at 1000℃ for 3 hours at a heating rate of 3℃ / min and a cooling rate of 3℃ / min to ensure good bonding between the cathode layer and the electrolyte, ultimately yielding a complete single cell. (Appendix) Figure 10 The IVP curve shows that (GPLBSC) 0.93 The CO anode-supported single cell achieves a maximum power density of 1.91 W·cm⁻¹ at 700°C. -2 It is 66.95% higher than (GPLBSC)CO.

[0099] I. Supplement to Testing and Characterization Methods

[0100] 1. The phase structure of the cathode material was determined using X-ray diffraction (Cu Kα radiation) with a scanning range of 5°–90° and a scanning rate of 2°·min. -1 The cell parameters were refined and analyzed using Jade software and Rietveld.

[0101] 2. Conduct conductivity tests: Approximately 3g of cathode powder was placed in a rectangular mold and pressed into a dense cathode strip under a pressure of 11MPa. The strip was then sintered at 1100°C for 12 hours to ensure a density of over 90%. The sample was then tested using a four-probe method in an air environment within a temperature range of 300-800°C.

[0102] 3. Electrochemical performance was measured using a CORRTEST electrochemical workstation (EIS testing) and an Arbin workstation (IVP curve testing). The EIS testing frequency range was 10. 6 ~10 -2 Hz, test temperature 500-700℃, oxygen partial pressure 0.05~0.21 atm.

[0103] II. Expanded Applications of Materials

[0104] The A-site defect-controlled high-entropy cobalt-based double perovskite material of the present invention can be used not only as SOFC cathodes, but also as an electrocatalytic material. It can be applied to oxygen reduction / oxygen evolution reactions in metal-air batteries and water electrolyzers, as well as electrocatalysis fields such as carbon dioxide electroreduction and nitrogen reduction. The material parameters can be adjusted to meet the needs of different electrocatalytic reactions.

[0105] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-entropy cobalt-based double perovskite solid oxide cathode material regulated by A-site defects, characterized in that, It consists of A-site defect-type derivatives of basic high-entropy cobalt-based double perovskites; among which, The A-site defect type derivative is formed by introducing 7% A-site cation defects into the basic high-entropy cobalt-based double perovskite structure; The A-site of the basic high-entropy cobalt-based double perovskite structure is composed of Gd, Pr, La, Ba, Sr and Ca in equimolar ratio, with an entropy value ≥1.5R; the B-site is Co. The general chemical formula of the A-site defective derivative is (Gd 1 / 6 Pr 1 / 6 La 1 / 6 Ba 1 / 6 Sr 1 / 6 Ca 1 / 6 ) 0.93 CoO3.

2. A method for preparing a high-entropy cobalt-based double perovskite solid oxide cathode material with A-site defect modulation, characterized in that, The specific steps are as follows: (1) According to the stoichiometric ratio of the A-site defective derivative as described in claim 1, weigh Gd2O3 and Pr6O 11 La2O3, BaCO3, SrCO3, CaCO3 and Co(NO3)2·6H2O, for later use; (2) Dissolve Gd2O3 in dilute nitric acid solution, and then add Pr6O4 sequentially. 11 La2O3, BaCO3, SrCO3, CaCO3 and Co(NO3)2·6H2O were mixed and then a complexing agent was added. The mixture was heated and stirred, then cooled and the pH was adjusted to 7-8. After stirring, the temperature was raised to evaporate the water to obtain a gel. (3) The gel is heated and dried to obtain cathode precursor powder; (4) Sinter the cathode precursor powder to obtain an A-site defect type derivative, denoted as (GPLBSC). 0.93 CO; The complexing agent is citric acid and ethylenediaminetetraacetic acid; The citric acid is 1.5 times the total molar amount of metal ions, and the ethylenediaminetetraacetic acid is 0.5 times the total molar amount of metal ions; In step (4), the sintering is performed at 1000℃ for 5 hours.

3. The preparation method according to claim 2, characterized in that, In step (2), the temperature is lowered to 90°C after heating and stirring for 15 minutes and then lowered to 40°C; the stirring time is 4 hours.

4. The application of the high-entropy cobalt-based double perovskite solid oxide cathode material with A-site defect modulation obtained by any of the preparation methods described in claims 2-3, characterized in that, The high-entropy cobalt-based double perovskite solid oxide cathode material regulated by the A-site defect can be used as an SOFC cathode; or as an electrocatalytic material, applied to oxygen reduction / oxygen evolution reactions in metal-air batteries and water electrolyzers, as well as electrocatalysis for carbon dioxide electroreduction and nitrogen reduction.

Images