A composite solid electrolyte doped with stannate-based solid electrolyte and a preparation method thereof

Abstract

The application relates to a composite solid electrolyte doped with a stannate-based solid electrolyte and a preparation method, and belongs to the field of sintering aids for solid electrolytes. The composite solid electrolyte doped with the stannate-based solid electrolyte comprises a stannate solid electrolyte and a zirconate solid electrolyte, the molecular formula of the stannate solid electrolyte is ASn 1‑x B x O 3‑α , and the molecular formula of the zirconate solid electrolyte is MZr 1‑y N y O 3‑α . The mixed solid electrolyte proton conductor material prepared by the application has a compact structure, a higher relative density, and higher sintering activity. The stannate oxide solid electrolyte which is easy to sinter and has stable chemical properties is used as a sintering aid, and the ASnO3 stannate-based solid electrolyte material which has a low sintering temperature, thermal stability and chemical stability is added to prepare the mixed solid electrolyte proton conductor material.

Description

Technical Field

[0001] This invention belongs to the field of sintering aids for solid electrolytes, and relates to a composite solid electrolyte and its preparation method for a doped stannate-based solid electrolyte. Background Technology

[0002] Perovskite-type solid electrolyte proton conductors are functional materials that use protons as charge carriers. Perovskite proton conductors have broad application prospects in fuel cells, hydrogen sensors, hydrogen separation, hydrogen production, and ammonia synthesis. The simple perovskite structure ABO3 is cubic, tetragonal, or orthorhombic, where the A-site is typically a +2 valent cation (such as Ba, Ca, Sr, etc.), and the B-site is a +4 valent cation (such as Zr, Ce, etc.). Typically, trivalent rare earth elements are used to dope the tetravalent B-site element, creating oxygen vacancies in the raw material. These oxygen vacancies can capture water vapor or hydrogen in the atmosphere, introducing protons and resulting in proton conductivity.

[0003] Zirconate-based solid electrolytes are the most common ABO3-type solid electrolytes. AZrO3 zirconate-based materials possess better thermal and chemical stability than ACeO3 cerium-based materials, but their sintering performance is poor, generally requiring higher temperatures (e.g., above 1700℃ for BaZrO3) to obtain a dense sintered body, leading to complex preparation processes and increased costs. To improve the sintering activity of doped AZrO3 zirconate-based materials and lower the required sintering temperature, sintering aids are typically added. By adding low-melting-point transition metal oxides (XO), such as Cu, Ni, Zn, Co, and Fe, as sintering aids, the density of BaZrO3 can be increased from 60% to approximately 90%, and the sintering temperature lowered to below 1600℃. However, when used in a reducing atmosphere, transition metal elements such as Cu or Co in these sintering aids are reduced to lower valence states or even elemental metals, thus introducing electronic conductivity into the electrolyte. This leads to reduced performance in batteries and other devices, and also damages the electrolyte structure, reducing its lifespan. Summary of the Invention

[0004] To address the issue that current sintering aids used for doped zirconate solid electrolytes typically contain transition metal elements, which are easily reduced in reducing atmospheres such as H2, leading to increased conductivity and reduced lifespan, this invention overcomes the limitations of liquid-phase sintering mechanisms in sintering aids. It expands the selection range of sintering aids for doped zirconate materials. Due to the ease of sintering and chemical stability of stannate oxide solid electrolytes, which do not reduce to elemental metals, ASnO3 stannate solid electrolyte materials possess low sintering temperature, thermal stability, and chemical stability. Doped ASnO3 solid electrolytes exhibit high hydration and high proton transfer number. When used as a sintering aid and mixed with zirconate-based solid electrolytes, it can achieve a density of over 90% at 1550℃ and exhibits excellent electrochemical performance. Adding it to zirconate-based solid electrolytes forms a composite oxide electron conductor material, giving it excellent sintering and electrochemical properties.

[0005] A composite solid electrolyte doped with a stannate-based solid electrolyte comprises a stannate solid electrolyte and a zirconate solid electrolyte, wherein the stannate solid electrolyte has the molecular formula ASn. 1-x B x O 3-α The element at site A is any one of Ba, Ca, and Sr, and the element at site B is any one of the +3 valent rare earth elements such as In, Sc, Gd, Sm, Y, Yb, and Dy. x = 0 to 0.4, and the value of 3-α is balanced according to the total valence state. The molecular formula of the zirconate solid electrolyte is MZr. 1-y N y O 3-α The M-site element is any one of Ba, Ca, and Sr, and the N-site element is any one of the +3 rare earth elements In, Sc, Gd, Sm, Y, Yb, Dy, etc., where y = 0 to 0.3, and the value of 3-α is balanced according to the total valence state. If x is greater than 0, the N-site element is consistent with the B-site element of the stannate solid electrolyte.

[0006] Furthermore, the ASn 1-x B x O 3-α With MZr 1-y N y O 3-α The molar ratio is 0.1 to 1.

[0007] A method for preparing a composite solid electrolyte doped with zirconate solid electrolyte, comprising the following steps:

[0008] Step 1: Preparation of stannate powder

[0009] Method 1: Solid-phase reaction method

[0010] Prepare oxides, carbonates or nitrates of elements A, B and Sn as raw materials. Place all raw materials in a ball mill jar and add anhydrous ethanol to ball mill and mix. Then press the mixture into blocks, calcine it and cool it to room temperature in the furnace. Ball mill the calcined material to obtain stannate powder.

[0011] Method 2: Sol-gel method

[0012] Prepare inorganic metal salts or metal alkoxides of elements A, B, and Sn as raw materials, dissolve them in a solvent to form a homogeneous solution; after constant temperature stirring, hydrolysis and polymerization reactions occur to generate a homogeneous sol, which is then dried or dehydrated to transform into a gel; the gel is then ashed in a muffle furnace and ball-milled into a fine powder to obtain ASN. 1-x B x O 3-α Precursor; ASn 1-x B x O 3-α The precursor is calcined at 700–1200℃ for 5–10 h to obtain stannate powder;

[0013] Step 2: Preparation of zirconate powder

[0014] If step 1 adopts method one, then prepare oxides, carbonates or nitrates of M, N and Zr elements as raw materials, put all raw materials into a ball mill jar and add anhydrous ethanol to ball mill and mix, then press into blocks, calcine and cool to room temperature with the furnace, ball mill the calcined material to obtain zirconate powder;

[0015] If step 1 uses method 2, then prepare metal inorganic salts or metal alkoxides of M, N, and Zr as raw materials, dissolve them in a solvent to form a homogeneous solution, and conduct hydrolysis and polymerization reactions under constant temperature stirring to generate a homogeneous sol. After drying or dehydration, the sol is converted into a gel. The gel is then placed in a muffle furnace for ashing and ball-milled into a fine powder to obtain MZr. 1-y N y O 3-α Precursor; MZr 1-y N y O 3-α The precursor is calcined at 900–1300℃ for 5–12 h to obtain zirconate powder;

[0016] Step 3: Preparation of mixed powder

[0017] The stannate powder obtained in step 1 and the zirconate powder obtained in step 2 are mixed and ball-milled to obtain a mixed powder;

[0018] Step 4: Preparation of solid electrolyte proton conductor materials

[0019] The mixed powder is pressed into blocks, sintered, and then cooled to room temperature in a furnace to produce a mixed solid electrolyte proton conductor material.

[0020] Furthermore, the ball milling described in steps 1 and 2 is ball milling until the average particle size is ≤5μm, and the pressing pressure of the compressed block is 5-10MPa.

[0021] Furthermore, in step 1, the calcination temperature is 1000℃~1200℃, and the calcination time is 5~20h.

[0022] Further, the solvents mentioned in Step 1, Method 2, and Step 2 are deionized water or alcohol solutions; before the hydrolysis and polymerization reactions occur, a complexing agent is added to the homogeneous solution, the amount of which is 1-3 times the molar amount of the cations in the raw materials; after the complexing agent is completely dissolved, the pH value is adjusted to 7-10 with ammonia; the complexing agent is citric acid, oxalic acid, or ethylenediaminetetraacetic acid; the ashing conditions are in an air atmosphere at a temperature of 200-300°C.

[0023] Furthermore, the calcination temperature in step 2 is 1300℃~1400℃, and the calcination time is 5~20h.

[0024] Furthermore, the mixing ratio of stannate powder and zirconate powder in step 3 is 0.1 to 1 in molar ratio, and the ball milling is carried out until the average particle size is ≤10μm.

[0025] Furthermore, the sintering temperature in step 4 is 1450–1600°C, and the sintering time is 5–20 hours.

[0026] Furthermore, the pressing pressure for forming the block in step 4 is 100-300 MPa.

[0027] The beneficial effects of this invention are that the mixed solid electrolyte proton conductor material prepared by this invention has a dense structure, a high relative density, and higher sintering activity. It uses stannate oxide solid electrolyte that is easy to sinter and has stable chemical properties as a sintering aid, and adds ASnO3 stannate-based solid electrolyte material with low sintering temperature, thermal stability and chemical stability to prepare the mixed solid electrolyte proton conductor material.

[0028] The stannate-based solid electrolyte material of the present invention can be used as a sintering aid to reduce the sintering temperature and improve the performance of zirconate-based solid electrolytes, forming a composite oxide proton conductor material. This material can both limit the electronic conductivity of the material and improve the sintering performance and proton conductivity, showing good application prospects. Attached Figure Description

[0029] Figure 1 BaZr in Embodiment 1 of the present invention 0.8 Y 0.2 O 2.9 CaSnO3 and BaZr 0.8 Y0.2 O 2.9 XRD pattern of CaSnO3 composite solid electrolyte;

[0030] Figure 2 These are BaZr sintered at 1550℃ in Example 1 of the present invention. 0.8 Y 0.2 O 2.9 SEM image of solid electrolyte;

[0031] Figure 3 The BaZr sintered at 1550℃ in Example 1 of this invention 0.8 Y 0.2 O 2.9 SEM image of CaSnO3 solid electrolyte;

[0032] Figure 4 The Arrhenius curves of the mixed solid electrolyte proton conductor material prepared in this embodiment of the invention are shown in the figure. The curves are at a temperature of 500–700 °C and under a water-containing atmosphere of 20% O2 and the remainder being argon. The ▲ in the figure represents the BaZr sintered at 1550 °C in Example 1. 0.8 Y 0.2 O 2.9 ● represents the BaZr sintered at 1550℃ in Example 1. 0.8 Y 0.2 O 2.9 -CaSnO3;

[0033] Figure 5 The transference number is the mixed solid electrolyte proton conductor material prepared in Example 1 of this invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0035] The raw materials used in the embodiments of this invention are commercially available analytical grade reagents.

[0036] The grinding jar used in this embodiment of the invention is made of agate.

[0037] In this embodiment of the invention, both calcination and sintering are carried out in a silica tube furnace under an air atmosphere.

[0038] The hybrid solid electrolyte proton conductor material in this embodiment of the invention has a conductivity ≤ 5.0 × 10⁻⁶ at 500–700 °C. -3 S / cm.

[0039] In this embodiment of the invention, an isostatic pressing device is used for synthesis and pressing during step 6.

[0040] The raw materials in the embodiments of the present invention are carbonates, nitrates, metal alkoxides and oxides containing elements Ba, Zr, Y, Ca and Sn.

[0041] Example 1

[0042] A composite solid electrolyte doped with a stannate-based solid electrolyte comprises a stannate solid electrolyte and a zirconate solid electrolyte, wherein the stannate-based solid electrolyte has the molecular formula CaSnO3 and the zirconate-based solid electrolyte has the molecular formula BaZr. 0.8 Y 0.2 O 2.9 CaSnO3 and BaZr 0.8 Y 0.2 O 2.9 The molar ratio is 0.25.

[0043] A method for preparing a composite solid electrolyte doped with stannate-based solid electrolyte is as follows:

[0044] (1) Prepare SnO2 and CaCO3 powder as raw materials; the molar ratio of Sn to Ca in all raw materials is 1:1; put all raw materials in a ball mill jar and add anhydrous ethanol to ball mill and mix until the average particle size is ≤5μm, press into blocks, press pressure is 10MPa, then calcine in a box furnace at 1200℃ for 10 hours, cool to room temperature with the furnace, put the calcined material in a ball mill jar and ball mill until the average particle size is ≤5μm to obtain CaSnO3 powder;

[0045] (2) Prepare ZrO2, Y2O3 and BaCO3 powders as raw materials; the molar ratio of Ba, Zr and Y in all raw materials is 1:0.8:0.2; place all raw materials in a ball mill jar and add anhydrous ethanol to mix and ball mill until the average particle size is ≤5μm, press into blocks, and then calcine in a box furnace at 1400℃ for 10 hours. Cool to room temperature with the furnace, and place the calcined material in a ball mill jar to ball mill until the average particle size is ≤5μm to obtain BaZr 0.8 Y 0.2 O 2.9 The powder, its SEM image is as follows Figure 2 As shown;

[0046] (3) CaSnO3 powder and BaZr 0.8 Y 0.2 O 2.9 The powders were mixed and ball-milled at a molar ratio of 0.25 until the average particle size was ≤10μm to obtain the mixed powder.

[0047] (4) The mixed powder is pressed into blocks at a pressure of 200 MPa and sintered at 1550℃ for 12 hours. The blocks are then cooled to room temperature in the furnace to produce a mixed solid electrolyte proton conductor material. The XRD pattern of the prepared mixed solid electrolyte proton conductor material is shown in the figure. Figure 1As shown, the SEM image is as follows: Figure 3 As shown, the conductivity Arrhenius curve is as follows: Figure 4 As shown, the number of migrations is as follows Figure 5 As shown.

[0048] like Figure 2 As shown, BaZr powder without sintering aids is used. 0.8 Y 0.2 O 2.9 BaZr containing 20 mol% of the above sintering aids 0.8 Y 0.2 O 2.9 The powders were pressed into shapes and sintered under the same conditions. Dimensional shrinkage before and after sintering was measured, and scanning electron microscopy (SEM) images were observed. The results showed that the sample with added sintering aids was more dense and exhibited higher sintering activity. After sintering at 1550℃ for 5 hours, BaZr without sintering aids... 0.8 Y 0.2 O 2.9 The sample only achieved a relative density of about 60%, while the BaZr containing 20 mol% of the above-mentioned sintering aid... 0.8 Y 0.2 O 2.9 The relative density of the sample increased to approximately 96%. (Comparison) Figure 2 and Figure 3 It can be seen that, under sintering at 1550℃, the BaZr in Example 1... 0.8 Y 0.2 O 2.9 Solid electrolytes have many pores, BaZr 0.8 Y 0.2 O 2.9 -CaSnO3 solid electrolyte has large grains and no pores. Experimental results demonstrate that the sintering aid designed in this invention can significantly improve the sintering efficiency of BaZr. 0.8 Y 0.2 O 2.9 Improve the sintering activity of electrolyte materials and reduce the required sintering temperature.

[0049] Example 2

[0050] A composite solid electrolyte doped with a stannate-based solid electrolyte comprises a stannate solid electrolyte and a zirconate solid electrolyte, wherein the stannate-based solid electrolyte has the molecular formula CaSn. 0.8 In 0.2 O 2.9 Zirconate-based solid electrolyte with molecular formula BaZr 0.8 In 0.2 O 2.9 ;CaSn 0.2 In 0.2 O 2.9 and BaZr0.8 In 0.2 O 2.9 The molar ratio is 0.3.

[0051] A method for preparing a composite solid electrolyte doped with stannate-based solid electrolyte is as follows:

[0052] (1) Prepare SnO2, In2O3 and CaCO3 powders as raw materials; the molar ratio of Ca, Sn and In is 1:0.8:0.2; place all raw materials in a ball mill jar and add anhydrous ethanol to ball mill and mix until the average particle size is ≤5μm, press into blocks, press at a pressure of 10MPa, and then calcine in a box furnace at 1200℃ for 10 hours. Cool to room temperature with the furnace, place the calcined material in a ball mill jar and ball mill until the average particle size is ≤5μm to obtain CaSn 0.8 In 0.2 O 2.9 Powder;

[0053] (2) Prepare ZrO2, In2O3 and BaCO3 powders as raw materials; the molar ratio of Ba, Zr and Y in all raw materials is 1:0.8:0.2; place all raw materials in a ball mill jar and add anhydrous ethanol to mix and ball mill until the average particle size is ≤5μm, press into blocks, press at a pressure of 10MPa, and then calcine in a box furnace at 1350℃ for 12 hours. Cool to room temperature with the furnace, place the calcined material in a ball mill jar and ball mill until the average particle size is ≤5μm to obtain BaZr 0.8 In 0.2 O 2.9 Powder;

[0054] (3) CaSn 0.8 In 0.2 O 2.9 Powder and BaZr 0.8 In 0.2 O 2.9 The powders were mixed and ball-milled at a molar ratio of 0.3 until the average particle size was ≤10μm to obtain the mixed powder.

[0055] (4) The mixed powder was pressed into blocks at a pressure of 200 MPa and sintered at 1550℃ for 12 hours. The blocks were then cooled to room temperature in the furnace to obtain BaZr. 0.8 In 0.2 O 2.9 -BaZr 0.8 In 0.2 O 2.9 A solid electrolyte with a conductivity of 2.0 × 10⁻⁶ at 700 °C. -3 S / cm.

[0056] Example 3

[0057] A composite solid electrolyte doped with a stannate-based solid electrolyte comprises a stannate solid electrolyte and a zirconate solid electrolyte, wherein the stannate-based solid electrolyte has the molecular formula CaSn. 0.9 Sc 0.1 O 2.95 Zirconate-based solid electrolyte with molecular formula BaZr 0.8 Sc 0.2 O 2.9 ;CaSn 0.9 Sc 0.1 O 2.95 and BaZr 0.8 Sc 0.2 O 2.9 The molar ratio is 0.25.

[0058] A method for preparing a composite solid electrolyte doped with stannate-based solid electrolyte is as follows:

[0059] (1) Prepare SnCl4·5H2O, Ca(NO3)2, and Sc(NO3)3·H2O powders as raw materials; the molar ratio of Ca, Sn, and Sc in all raw materials is 1:0.9:0.1; dissolve all raw materials in deionized H2O, and after complete dissolution, add a certain amount of citric acid, the amount of which is 1.5 times the molar amount of cations in the raw materials. After the citric acid is completely dissolved, adjust the pH value to 8 with ammonia water; after constant temperature stirring, hydrolysis and polymerization reactions occur to generate a uniform sol, which is then dried or dehydrated to transform into a gel. The gel is then placed in a muffle furnace and burned at 300℃ in an air atmosphere, and then ground into a fine powder to obtain CaSn. 0.9 Sc 0.1 O 2.95 Precursor; CaSn 0.9 Sc 0.1 O 2.95 The precursor was calcined at 1000℃ for 6 hours to obtain stannate powder;

[0060] (2) Prepare Ba(NO3)2, Y(NO3)·6H2O, and Sc(NO3)3·H2O powders as raw materials; the molar ratio of Ba, Zr, and Sc in all raw materials is 1:0.8:0.2; dissolve all raw materials in deionized H2O, and after complete dissolution, add a certain amount of citric acid, the amount of which is 1.5 times the molar amount of cations in the raw materials. After the citric acid is completely dissolved, adjust the pH value to 8 with ammonia water; after constant temperature stirring, hydrolysis and polymerization reactions occur, generating a uniform sol, which is then dried or dehydrated to transform into a gel. The gel is then placed in a muffle furnace and burned at 300℃ in an air atmosphere, and then ground into a fine powder to obtain BaZr. 0.8 Sc 0.2 O 2.9 Precursor; BaZr0.8 Sc 0.2 O 2.9 The precursors were calcined at 1200℃ for 10 hours to obtain stannate powder.

[0061] (3) Mix the stannate powder and the stannate powder at a molar ratio of 0.25 and ball mill them to obtain a mixed powder;

[0062] (4) The mixed powder is pressed into blocks at a pressure of 200 MPa, sintered at 1500℃ for 12 hours, and then cooled to room temperature in the furnace to produce a mixed solid electrolyte proton conductor material. The resulting CaSn 0.9 Sc 0.1 O 2.95 -BaZr 0.8 Sc 0.2 O 2.9 The conductivity of the composite solid electrolyte at 700℃ is 4.0 × 10⁻⁶. -3 S / cm.

[0063] Example 4

[0064] A composite solid electrolyte doped with a stannate-based solid electrolyte comprises a stannate solid electrolyte and a zirconate solid electrolyte, wherein the stannate-based solid electrolyte has the molecular formula CaSn. 0.8 Gd 0.2 O 2.9 Zirconate-based solid electrolyte with molecular formula BaZ r0.8 Gd 0.2 O 2.9 ;CaSn 0.8 Gd 0.2 O 2.9 and BaZ r0.8 Gd 0.2 O 2.9 The molar ratio is 0.25.

[0065] The preparation methods of the composite solid electrolyte, stannate solid electrolyte, and zirconate solid electrolyte are the same as in Example 1, except that:

[0066] (1) The raw materials for the stannate solid electrolyte are SnO2, CaCO3 and Gd2O3 powders, and the molar ratio of Ca, Sn and Gd in all raw materials is 1:0.8:0.2;

[0067] (2) The raw materials for the zirconate solid electrolyte are ZrO2, BaCO3 and Gd2O3 powders, and the molar ratio of Ba, Sn and Gd in all raw materials is 1:0.8:0.2;

[0068] (3) The conductivity of the composite solid electrolyte at 700℃ is 5.1 × 10⁻⁶. -3 S / cm.

[0069] Example 5

[0070] A composite solid electrolyte doped with a stannate-based solid electrolyte comprises a stannate solid electrolyte and a zirconate solid electrolyte, wherein the stannate-based solid electrolyte has the molecular formula CaSn. 0.8 Yb 0.2 O 2.9 Zirconate-based solid electrolyte with molecular formula BaZ r0.8 Yb 0.2 O 2.9 ;CaSn 0.8 Yb 0.2 O 2.9 and BaZ r0.8 Yb 0.2 O 2.9 The molar ratio is 0.25.

[0071] The preparation methods of the composite solid electrolyte, stannate solid electrolyte, and zirconate solid electrolyte are the same as in Example 3, except that:

[0072] (1) The raw materials for the stannate solid electrolyte are SnO2, CaCO3 and Yb2O3 powders, and the molar ratio of Ca, Sn and Yb in all raw materials is 1:0.8:0.2;

[0073] (2) The raw materials for the zirconate solid electrolyte are ZrO2, BaCO3 and Yb2O3 powders, and the molar ratio of Ba, Sn and Yb in all raw materials is 1:0.8:0.2;

[0074] (3) The conductivity of the composite solid electrolyte at 700℃ is 4.8 × 10⁻⁶. -3 S / cm.

[0075] Example 6

[0076] A composite solid electrolyte doped with a stannate-based solid electrolyte comprises a stannate solid electrolyte and a zirconate solid electrolyte, wherein the stannate-based solid electrolyte has the molecular formula CaSn. 0.9 Dy 0.1 O 2.95 Zirconate-based solid electrolyte with molecular formula BaZ r0.9 Dy 0.1 O 2.95 ;CaSn 0.9 Dy 0.1 O 2.95 and BaZ r0.9 Dy 0.2 O 2.95 The molar ratio is 0.25.

[0077] The preparation methods of the composite solid electrolyte, stannate solid electrolyte, and zirconate solid electrolyte are the same as in Example 3, except that:

[0078] (1) The raw materials for the stannate solid electrolyte are Sncl4·5H2O, Ca(NO3)2 and Dy(NO3)3, and the molar ratio of Ca, Sn and Dy in all raw materials is 1:0.9:0.1;

[0079] (2) The raw materials for the zirconate solid electrolyte are Ba(NO3)2, Zr(NO3)2 and Dy(NO3)3, and the molar ratio of Ba, Sn and Dy in all raw materials is 1:0.9:0.1;

[0080] (3) The conductivity of the composite solid electrolyte at 700℃ is 4.6 × 10⁻⁶. -3 S / cm.

Claims

1. A composite solid electrolyte doped with stannate-based solid electrolyte, characterized in that, It includes stannate solid electrolytes and zirconate solid electrolytes, wherein the molecular formula of the stannate solid electrolyte is ASn. 1-x B x O 3-α The element at position A is any one of Ba, Ca, and Sr, and the element at position B is any one of the +3 valence elements In, Sc, Gd, Sm, Y, Yb, and Dy. x = 0~0.4, 3- α The value is balanced according to the total price state; The molecular formula of the zirconate solid electrolyte is MZr. 1-y N y O 3-α The M-position element is any one of Ba, Ca, and Sr, and the N-position element is any one of the +3 valence elements In, Sc, Gd, Sm, Y, Yb, and Dy. y =0~0.3 and y Not 0, 3- α The value is balanced according to the total valence state; the A-position element and the M-position element are different; if x If the value is greater than 0, then the N-site element is consistent with the B-site element of the stannate solid electrolyte; the ASn 1-x B x O 3-α With MZr 1-y N y O 3-α The molar ratio is 0.1 to 1.

2. A method for preparing a composite solid electrolyte of a doped zirconate solid electrolyte as described in claim 1, characterized in that, Follow these steps: Step 1: Preparation of stannate powder Method 1: Solid-phase reaction method Prepare oxides, carbonates or nitrates of elements A, B and Sn as raw materials. Place all raw materials in a ball mill jar and add anhydrous ethanol to ball mill and mix. Then press the mixture into blocks, calcine it and cool it to room temperature in the furnace. Ball mill the calcined material to obtain stannate powder. Method 2: Sol-gel method Prepare inorganic metal salts or metal alkoxides of elements A, B and Sn as raw materials, and dissolve them in a solvent to form a homogeneous solution; Hydrolysis and polymerization reactions occur under constant temperature stirring to generate a homogeneous sol, which is then dried or dehydrated to form a gel. The gel is then ashed in a muffle furnace and ball-milled into a fine powder to obtain Asn. 1-x B x O 3-α Precursor; ASn 1-x B x O 3-α The precursor is calcined at 700–1200℃ for 5–10 h to obtain stannate powder; Step 2: Preparation of zirconate powder If step 1 adopts method one, then prepare oxides, carbonates or nitrates of M, N and Zr elements as raw materials, put all raw materials into a ball mill jar and add anhydrous ethanol to ball mill and mix, then press into blocks, calcine and cool to room temperature with the furnace, ball mill the calcined material to obtain zirconate powder; If step 1 uses method 2, then prepare metal inorganic salts or metal alkoxides of M, N, and Zr as raw materials, dissolve them in a solvent to form a homogeneous solution, and conduct hydrolysis and polymerization reactions under constant temperature stirring to generate a homogeneous sol. After drying or dehydration, the sol is converted into a gel. The gel is then placed in a muffle furnace for ashing and ball-milled into a fine powder to obtain MZr. 1-y N y O 3-α Precursor; MZr 1- y N y O 3-α The precursor is calcined at 900–1300℃ for 5–12 h to obtain zirconate powder; Step 3: Preparation of mixed powder The stannate powder obtained in step 1 and the zirconate powder obtained in step 2 are mixed and ball-milled to obtain a mixed powder; Step 4: Preparation of solid electrolyte proton conductor materials The mixed powder is pressed into blocks, sintered, and then cooled to room temperature in a furnace to produce a mixed solid electrolyte proton conductor material.

3. The method for preparing a composite solid electrolyte of a doped zirconate solid electrolyte according to claim 2, characterized in that, The ball milling in steps 1 and 2 is to mill until the average particle size is ≤5μm, and the pressing pressure for pressing into blocks is 5~10MPa.

4. The method for preparing a composite solid electrolyte of a doped zirconate solid electrolyte according to claim 2, characterized in that, In step 1 of method one, the calcination temperature is 1000℃~1200℃ and the calcination time is 5~20h.

5. The method for preparing a composite solid electrolyte of a doped zirconate solid electrolyte according to claim 2, characterized in that, The solvents used in Step 1 (Method 2) and Step 2 are deionized water or alcohol solutions. Before the hydrolysis and polymerization reactions occur, a complexing agent is added to the homogeneous solution. The amount of the complexing agent is 1-3 times the molar amount of the cations in the raw materials. After the complexing agent is completely dissolved, the pH value is adjusted to 7-10 with ammonia. The complexing agent is citric acid, oxalic acid, or ethylenediaminetetraacetic acid. The ashing conditions are in an air atmosphere at a temperature of 200-300°C.

6. The method for preparing a composite solid electrolyte of a doped zirconate solid electrolyte according to claim 2, characterized in that, In step 2, the calcination temperature is 1300℃~1400℃ and the calcination time is 5~20h.

7. The method for preparing a composite solid electrolyte of a doped zirconate solid electrolyte according to claim 2, characterized in that, The mixing ratio of stannate powder and zirconate powder in step 3 is 0.1 to 1 in molar ratio, and the ball milling is carried out until the average particle size is ≤10μm.

8. The method for preparing a composite solid electrolyte of a doped zirconate solid electrolyte according to claim 2, characterized in that, The sintering temperature in step 4 is 1450–1600℃, and the sintering time is 5–20 hours.

9. The method for preparing a composite solid electrolyte of a doped zirconate solid electrolyte according to claim 2, characterized in that, The pressing pressure for forming the block in step 4 is 100~300MPa.

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