A solid electrolyte high entropy ceramic with high electrical conductivity and preparation method thereof

Abstract

The present invention provides a high-conductivity solid-state electrolyte high-entropy ceramic and a preparation method thereof, relating to the field of ceramics. The present invention incorporates Er, Dy, Gd, Zr, and Y into a δ-Bi2O3-based electrolyte lattice, thereby significantly increasing the sample's configurational entropy and lattice distortion, enhancing the stability of the sample's fluorite-type lattice, promoting the formation of oxygen vacancies, and improving its oxygen ion conductivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramics, and in particular relates to a solid electrolyte high-entropy ceramic with high electrical conductivity and a preparation method thereof. Background Art

[0002] To date, the commonly used oxygen ion solid electrolyte ceramics that have been developed and studied primarily include zirconium oxide-based, ceria-based, lanthanum gallate-based, and bismuth oxide-based oxygen ion solid electrolytes. The first three electrolytes have relatively low conductivity, while bismuth oxide-based oxygen ion solid electrolyte ceramics with defective fluorite structures exhibit higher oxygen ion conductivity, primarily due to the 25% intrinsic oxygen defects in their lattice. However, pure Bi2O3 exhibits different crystal structures at different temperatures. The fluorite-type Bi2O3 (δ-Bi2O3), with its higher oxygen ion conductivity, is stable between 730°C and 825°C. When the temperature drops below 730°C or rises above 825°C, Bi2O3 undergoes a phase transition or transforms into a molten state. To ensure that Bi2O3 maintains a stable δ-Bi2O3 phase from room temperature to the operating temperature of O-SOFCs, element doping is often used to broaden the temperature range of its crystal stability.

[0003] While traditional single-element or two-element co-doping methods prevent phase transitions in δ-Bi2O3-based electrolytes at low temperatures, their electrical conductivity at medium and low temperatures still needs to be further improved. Furthermore, single-element or multi-element doped δ-Bi2O3-based electrolytes suffer from poor long-term operational stability. At medium and low temperatures, their oxygen ion conductivity gradually decays over time before stabilizing. This is primarily due to the disorder-to-order transition of the anion sublattice within the δ-Bi2O3-based electrolyte's crystal structure. Currently, there have been no studies or reports on the high-entropy design of δ-Bi2O3-based electrolyte ceramic materials. High-entropy ceramics generally refer to multi-principal-component solid solution ceramics composed of five or more elements in equal or near-equimolar ratios. Reports on high-entropy ceramic materials suggest that leveraging the high mixing entropy and hysteretic diffusion effect of high-entropy materials can improve the thermal stability of δ-Bi2O3-based electrolyte ceramics, inhibit phase transitions, and thus further enhance their performance.

[0004] Aiming at the current situation that the conductivity of existing oxygen ion conductors is low and bismuth oxide has phase change and crystal transformation, the present invention adopts a high entropy design strategy to provide a high conductivity (Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) x Bi 1-x )2O3 oxygen ion solid electrolyte high entropy ceramics. Summary of the Invention

[0005] Based on this, the present invention provides a high-conductivity solid electrolyte high-entropy ceramic and its preparation method. By introducing five elements (Er, Dy, Gd, Zr, and Y) in equal molar ratios into the sample's fluorite-type lattice, the present invention increases the sample's configurational entropy and lattice distortion, thereby enhancing the sample's lattice stability and oxygen ion conductivity.

[0006] Specifically, the present invention is implemented by adopting the following technical solutions:

[0007] A solid electrolyte high entropy ceramic with high electrical conductivity, characterized in that the structure of the solid electrolyte high entropy ceramic is as follows:

[0008] (Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) x Bi 1-x )2O3,

[0009] Where x = 0.1 ~ 0.2.

[0010] Preferably, the solid electrolyte high entropy ceramic of the present invention has a cubic fluorite crystal structure and is composed of irregular polygonal grains.

[0011] The method for preparing a solid electrolyte high entropy ceramic with high electrical conductivity of the present invention comprises the following steps:

[0012] (1) Er2O3 powder, Dy2O3 powder, Gd2O3 powder, ZrO2 powder, Y2O3 powder and Bi2O3 powder were weighed in stoichiometric proportions, and then the weighed oxide powders were ball-milled to obtain a mixed powder;

[0013] (2) calcining the mixed powder in a muffle furnace, and grinding and sieving the mixed powder after calcination to obtain a precursor powder;

[0014] (3) Pressing the precursor powder into a disc, placing the disc in a crucible, laying the precursor powder on the bottom of the crucible, and then sintering it in a muffle furnace to obtain a solid electrolyte high entropy ceramic.

[0015] Preferably, the ball milling media in step (1) of the present invention are zirconium oxide grinding balls and anhydrous ethanol, wherein the mass ratio of the raw material powder to the zirconium oxide grinding balls and anhydrous ethanol is 1:(5-6):(5-6), the ball mill speed is 300-350 rpm, and the ball milling time is 20-24 hours. In some embodiments, the present invention fully dries the light yellow slurry after ball milling, and then grinds the dried light yellow block into a fine powder to obtain a mixed powder. The drying temperature is preferably 100-110° C., and the drying time is preferably 10-12 hours.

[0016] Preferably, the muffle furnace calcination temperature in step (2) is 500-600° C., and the calcination time is 5-6 hours.

[0017] In some embodiments, the present invention forms a disc having a diameter of 10 mm and a thickness of 1.5 mm by pressing the precursor powder at a pressure of 112 to 135 MPa for 5 to 15 minutes.

[0018] Preferably, in step (3), the sintering temperature in the muffle furnace is 800-950° C., and the holding time is 8-10 hours.

[0019] Principle of the present invention: Although the traditional single-element doping or two-element co-doping method prevents the phase transition of δ-Bi2O3-based electrolytes at low temperatures, its oxygen ion conductivity at medium and low temperatures (≤500°C) is low. At the same time, single-element doping or co-doping of δ-Bi2O3-based electrolytes also has the problem of poor long-term structural stability. The present invention selects five elements with different ionic radii and atomic masses and adds them to the sample lattice, which can significantly improve the configurational entropy and lattice distortion of the sample, increase the stability of the sample's fluorite lattice, promote the formation of oxygen vacancies, and improve its oxygen ion conductivity.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) (Er) prepared by the present invention 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) x Bi 1-x )2O3 oxygen ion solid electrolyte high entropy ceramics, after being doped with five specific elements in equal proportions, have a maximum oxygen ion conductivity (4.05×10 -2 S / cm) is one to two orders of magnitude higher than that of traditional oxygen ion solid electrolyte ceramics such as doped Bi2O3-based ceramics, CeO2-based ceramics and yttria-stabilized zirconia ceramics (8.24×10 -4 S / cm~6.29×10 -3 S / cm(500℃)).

[0022] (2) (Er) prepared by the present invention 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) x Bi 1-x After the )2O3 oxygen ion solid electrolyte high entropy ceramics were kept at 500℃ for a long time (100h), its phase structure remained stable and no other phases were generated. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 XRD patterns of the solid electrolyte high entropy ceramics prepared in Examples 1 to 3 and Comparative Example 1 after sintering;

[0024] Figure 2 XRD patterns of the solid electrolyte high entropy ceramics prepared in Examples 1 to 3 and Comparative Example 1 after annealing at 500° C. for 100 h;

[0025] Figure 3 SEM and EDS images of the solid electrolyte high entropy ceramics prepared in Examples 1 to 3;

[0026] Figure 4 Arrhenius plots, AC impedance plots and conductivity of the solid electrolyte high entropy ceramics prepared in Examples 1 to 3 and Comparative Example 1 at 200 to 600 ° C, DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions and advantages of the present invention more clear, the preferred embodiments of the present invention are further described in detail below with reference to the examples. Based on the examples in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] Example 1

[0029] A high conductivity (Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.1 Bi 0.9 ) The preparation method of 2O3 oxygen ion solid electrolyte high entropy ceramics, the specific steps are as follows:

[0030] (1) According to ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.1 Bi0.9 )2O3 were weighed in a stoichiometric ratio of Er2O3, Dy2O3, Gd2O3, ZrO2, Y2O3 and Bi2O3, and then the weighed oxide powders were poured into a zirconia ball mill jar, zirconia grinding balls and anhydrous ethanol were added as ball milling media, the mass ratio of raw material powder, zirconia grinding balls and anhydrous ethanol was 1:5:5, and a planetary ball mill was used to mill for 24 hours at a speed of 300 rpm.

[0031] (2) The light yellow slurry obtained in step (1) was poured into a glass dish and placed in a drying oven at 100°C for 12 hours. The dried light yellow block was then ground into a fine powder using an agate mortar and poured into an alumina crucible and placed in a muffle furnace for calcination at 500°C for 6 hours to synthesize ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.1 Bi 0.9 )2O3 precursor powder.

[0032] (3) The ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.1 Bi 0.9 )2O3 precursor powder was ground in an agate mortar for half an hour and passed through a 300-mesh sieve. Then, a stainless steel mold and a powder tablet press were used to press ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.1 Bi 0.9 )2O3 precursor powder was pressed into a disc with a diameter of 10mm and a thickness of 1.5mm, and the pressure was maintained for 5min. Finally, the disc was placed in an alumina crucible, and the bottom of the crucible was covered with ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.1 Bi 0.9 )2O3 precursor powder was placed in a muffle furnace and kept at 800℃ for 10h to obtain ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.1 Bi 0.9)2O3 oxygen ion solid electrolyte high entropy ceramics.

[0033] Example 2

[0034] A high conductivity (Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.15 Bi 0.85 ) The preparation method of 2O3 oxygen ion solid electrolyte high entropy ceramics, the specific steps are as follows:

[0035] (1) According to ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.15 Bi 0.85 )2O3 in a stoichiometric ratio of Er2O3, Dy2O3, Gd2O3, ZrO2, Y2O3 and Bi2O3 were weighed respectively, and then the weighed oxide powders were poured into a zirconia ball mill jar, zirconia grinding balls and anhydrous ethanol were added as ball milling media, the mass ratio of raw material powder, zirconia grinding balls and anhydrous ethanol was 1:6:6, and a planetary ball mill was used to mill for 20 hours at a speed of 350 rpm.

[0036] (2) The light yellow slurry obtained in step (1) was poured into a glass dish and placed in a drying oven at 110°C for 10 h. The dried light yellow block was then ground into a fine powder using an agate mortar and poured into an alumina crucible and placed in a muffle furnace for calcination at 600°C for 5 h to synthesize ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.15 Bi 0.85 )2O3 precursor powder.

[0037] (3) The ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.15 Bi 0.85 )2O3 precursor powder was ground in an agate mortar for half an hour and passed through a 300-mesh sieve. Then, a stainless steel mold and a powder tablet press were used to press ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y0.2 ) 0.15 Bi 0.85 )2O3 precursor powder was pressed into a disc with a diameter of 10mm and a thickness of 1.5mm, and the pressure was maintained for 10min. Finally, the disc was placed in an alumina crucible, and the bottom of the crucible was covered with ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.15 Bi 0.85 )2O3 precursor powder was placed in a muffle furnace and kept at 900℃ for 10h to obtain ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.15 Bi 0.85 )2O3 oxygen ion solid electrolyte high entropy ceramics.

[0038] Example 3

[0039] A high conductivity (Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.2 Bi 0.8 ) The preparation method of 2O3 oxygen ion solid electrolyte high entropy ceramics, the specific steps are as follows:

[0040] (1) According to ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.2 Bi 0.8 )2O3 in a stoichiometric ratio of Er2O3, Dy2O3, Gd2O3, ZrO2, Y2O3 and Bi2O3 were weighed respectively, and then the weighed oxide powders were poured into a zirconia ball mill jar, zirconia grinding balls and anhydrous ethanol were added as ball milling media, the mass ratio of raw material powder, zirconia grinding balls and anhydrous ethanol was 1:5:5.5, and a planetary ball mill was used to mill for 22 hours at a speed of 330 rpm.

[0041] (2) The light yellow slurry obtained in step (1) was poured into a glass dish and placed in a drying oven at 105°C for 11 hours. The dried light yellow block was then ground into a fine powder using an agate mortar and poured into an alumina crucible and placed in a muffle furnace for calcination at 550°C for 5.5 hours to synthesize ((Er 0.2 Dy 0.2 Gd0.2 Zr 0.2 Y 0.2 ) 0.15 Bi 0.85 )2O3 precursor powder.

[0042] (3) The ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.2 Bi 0.8 )2O3 precursor powder was ground in an agate mortar for half an hour and passed through a 300-mesh sieve. Then, a stainless steel mold and a powder tablet press were used to press ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.2 Bi 0.8 )2O3 precursor powder was pressed into a disc with a diameter of 10mm and a thickness of 1.5mm, and the pressure was maintained for 15min. Finally, the disc was placed in an alumina crucible, and the bottom of the crucible was covered with ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.2 Bi 0.8 )2O3 precursor powder was placed in a muffle furnace and kept at 950℃ for 8h to obtain ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.2 Bi 0.8 )2O3 oxygen ion solid electrolyte high entropy ceramics.

[0043] Comparative Example 1

[0044] A single-doped Bi2O3-based oxygen ion solid electrolyte ceramic (Er 0.2 Bi 0.8 )2O3 preparation method, the specific steps are as follows:

[0045] (1) According to (Er 0.2 Bi 0.8)2O3 in a stoichiometric ratio of Er2O3 and Bi2O3, respectively, and then pour the weighed oxide powders into a zirconia ball mill jar, add zirconia grinding balls and anhydrous ethanol as ball milling media, the mass ratio of raw material powder, zirconia grinding balls and anhydrous ethanol is 1:5:5.5, and use a planetary ball mill at a speed of 330 rpm for 22 hours.

[0046] (2) The light yellow slurry obtained in step (1) was poured into a glass dish and placed in a drying oven at 105°C for 11 hours. The dried light yellow block was then ground into a fine powder using an agate mortar and poured into an alumina crucible and placed in a muffle furnace for calcination at 550°C for 5.5 hours to synthesize (Er 0.2 Bi 0.8 )2O3 precursor powder.

[0047] (3) The (Er) obtained in step (2) 0.2 Bi 0.8 )2O3 precursor powder was ground in an agate mortar for half an hour and passed through a 300-mesh sieve. Then, a stainless steel mold and a powder tablet press were used to press (Er 0.2 Bi 0.8 )2O3 precursor powder was pressed into a disc with a diameter of 10mm and a thickness of 1.5mm, and the pressure was maintained for 15min. Finally, the disc was placed in an alumina crucible, and the bottom of the crucible was covered with (Er 0.2 Bi 0.8 )2O3 precursor powder was placed in a muffle furnace and kept at 950℃ for 8h to obtain (Er 0.2 Bi 0.8 )2O3 oxygen ion solid electrolyte high entropy ceramics.

[0048] from Figure 1 It can be seen that the diffraction peaks of each ceramic sample after high entropy treatment are consistent with the standard PDF card (PDF#27-0052), and the standard PDF card corresponds to the δ-Bi2O3 phase, indicating that the high entropy treatment can stabilize the high conductivity δ-Bi2O3 phase at room temperature;

[0049] from Figure 2 It can be seen that after annealing at 500℃ for 100h, the diffraction peaks of each sample are still consistent with the standard PDF card (PDF#27-0052), indicating that the high entropy treatment can make the high conductivity δ-Bi2O3 phase stable in a medium and low temperature (500℃) long-term working environment;

[0050] from Figure 3 It can be seen that the elements of high-entropy ceramic samples doped with different proportions are evenly distributed without obvious element segregation;

[0051] from Figure 4It can be seen that in the temperature range of 200-600℃, the comparison of CeO2-based, yttria-stabilized zirconia ceramics and single-doped (Er 0.2 Bi 0.8 )2O3 ceramics, the high entropy ceramics prepared by the present invention have a higher electrical conductivity than the three, and ((Er 0.2 Dy 0.2 Gd 0.2 Zr 0.2 Y 0.2 ) 0.2 Bi 0.8 )2O3 high entropy ceramics at medium and low temperature points (400, 500, 600℃) compared with single doping (Er 0.2 Bi 0.8 )2O3 ceramics, its electrical conductivity is improved by nearly 1 order of magnitude.

[0052] The embodiments described above are some, but not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

Claims

1. A solid electrolyte high entropy ceramic with high electrical conductivity, characterized in that: The structure of the solid electrolyte high entropy ceramic is as follows: (On 0.2 Of 0.2 Gd 0.2 Zr 0.2 THE 0.2 ) x Bi 1-x )2O3, Where x=0.1~0.

2.

2. The solid electrolyte high entropy ceramic with high conductivity according to claim 1, characterized in that: The solid electrolyte high entropy ceramic has a cubic fluorite crystal structure and is composed of irregular polygonal grains.

3. The method for preparing a solid electrolyte high entropy ceramic with high conductivity according to claim 1 or 2, characterized in that: The following steps are involved: (1) Er2O3 powder, Dy2O3 powder, Gd2O3 powder, ZrO2 powder, Y2O3 powder and Bi2O3 powder were weighed in stoichiometric proportions, and then the weighed oxide powders were ball-milled to obtain a mixed powder; (2) calcining the mixed powder in a muffle furnace, and grinding and sieving the mixed powder after calcination to obtain a precursor powder; (3) Pressing the precursor powder into a disc, placing the disc in a crucible, laying the precursor powder on the bottom of the crucible, and then sintering it in a muffle furnace to obtain a solid electrolyte high entropy ceramic.

4. The method for preparing a solid electrolyte high entropy ceramic with high conductivity according to claim 3, characterized in that: The ball milling media in step (1) are zirconia grinding balls and anhydrous ethanol, wherein the mass ratio of raw material powder to zirconia grinding balls and anhydrous ethanol is 1:(5-6):(5-6), the ball mill speed is 300-350 rpm, and the ball milling time is 20-24 h.

5. The method for preparing a solid electrolyte high entropy ceramic with high conductivity according to claim 3, characterized in that: The calcination temperature in the muffle furnace in step (2) is 500-600 ° C, calcination time is 5~6 h.

6. The method for preparing a solid electrolyte high entropy ceramic with high conductivity according to claim 3, characterized in that: The sintering temperature of the muffle furnace in step (3) is 800~950 ° C, the holding time is 8~10 h.

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