A solid oxide half-cell with a thin electrolyte layer and a method for preparing the same

Abstract

The present invention relates to a solid oxide half-cell with a thin electrolyte layer and a preparation method thereof. The solid oxide half-cell with a thin electrolyte layer described in the present invention comprises: a finger-like pore structure support layer with a thickness of 250-2500 μm; a dense structure functional support layer with a thickness of 1-30 μm, and a dense electrolyte layer with a thickness of 0.5-5 μm, and the preparation method is a combination of casting phase transformation and interface induction technology. The electrolyte of the half-cell of the present invention has the characteristics of thin thickness, density, and thermochemical matching with the electrolyte layer, which not only reduces the ion transmission resistance, but also maintains the integrity of the multilayer battery, thereby improving the working stability of the battery. The present invention provides a solid oxide half-cell with a thin electrolyte layer prepared by using an interface induction technology, and the preparation process is relatively simple and easy to scale up, which helps to promote the popularization and application of solid oxide batteries.

Description

Technical Field

[0001] The invention relates to the technical field of solid oxide fuel cells and electrolytic cells, and in particular to a solid oxide half-cell with an electrolyte thin layer and a preparation method thereof. Background Art

[0002] The information disclosed in the background of the invention is only intended to enhance the understanding of the overall background of the invention and should not be necessarily regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Solid oxide fuel cells (SOFCs) can directly convert chemical energy stored in fuel (without converting it into heat energy) into electrical energy in an efficient and clean way at high temperature. They also have the advantages of high energy conversion efficiency, no pollution, and wide fuel applicability. As the reverse process of SOFC, solid oxide fuel electrolyzer (SOEC) is a device that directly converts electrical energy into chemical energy, such as electrolyzing water to produce hydrogen. Therefore, reversible solid oxide cells (RSOCs) that can combine the functions of SOFC and SOEC are attracting more and more attention.

[0004] One of the effective ways to improve the energy conversion efficiency of SOFC or SOEC cells is to thin the electrolyte layer to reduce the internal resistance of the battery, reduce internal consumption, and improve the output performance of the battery. At present, the methods for preparing electrolyte thin films mainly include chemical methods, physical methods, and ceramic powder processes. The electrolytes prepared by chemical methods (including vapor deposition, sol-gel method, spray pyrolysis method) and physical methods (including radio frequency sputtering, magnetron sputtering, thermal spraying, laser deposition) are thin, high in purity, and compact in structure, but the disadvantages are that the preparation price is expensive, the production efficiency is not high, the coating and the substrate are thermochemically incompatible, and sometimes toxic by-products are released. The electrolytes prepared by ceramic powder processes (including phase inversion method, slurry coating method, screen printing method, spin coating method, dry pressing method, etc.) are low in price and suitable for large-scale production, but the electrolyte thickness is large, and the electrode-supported battery prepared by this process also faces the problem of thermochemical mismatch between the electrode layer and the electrolyte layer. The traditional technology for preparing half-cells with electrolyte thin films faces problems such as complicated processes, high costs, and easy peeling between layers. Therefore, it is urgent to develop a simple method for preparing half-cells with thin electrolyte layers and good compatibility between layers. Summary of the invention

[0005] In view of the shortcomings of the existing preparation technology, the present invention provides a solid oxide half-cell with a thin electrolyte layer prepared by combining tape casting phase conversion and interface induction. The preparation method provided by the present invention saves the steps of screen printing, spraying, chemical deposition, etc. in the traditional process, simplifies the process and reduces the cost; the thickness of the electrolyte layer is easy to control, and the thinnest can reach 5 microns, which can significantly reduce the oxygen ion transmission resistance and improve the battery performance. In the present invention, since the electrolyte thin layer is induced from the functional layer, it has strong adhesion with the electrode support layer and is not easy to be delaminated and peeled off, thereby improving the stability of the battery during long-term operation.

[0006] To achieve the above object, the present invention provides the following technical methods:

[0007] In a first aspect of the present invention, a method for preparing a solid oxide half-cell having an electrolyte thin layer is provided, wherein the solid oxide half-cell comprises: a finger-like pore structure support layer, a dense structure functional support layer and a dense electrolyte layer; the preparation method comprises the use of a combination of tape casting phase conversion and interface induction technology, and the preparation method comprises the following steps:

[0008] (1) mixing a polymer, an organic solvent and a supporting layer ceramic powder containing an electrolyte to prepare a slurry;

[0009] (2) tape-casting the slurry and immersing it in a non-solvent to obtain an initial green body;

[0010] (3) After the green body is dried, cut, and shaped, it is calcined at high temperature to obtain a pre-calcined body having a finger-like pore structure and a dense structure support layer;

[0011] (4) placing the pre-calcined body on an alumina substrate, wherein one side of the dense structure functional support layer is in contact with the alumina substrate, and forming a dense thin layer on the surface of the dense structure functional support layer after high-temperature interface induction, thereby obtaining a three-layer structure solid oxide half-cell.

[0012] In the above three-layer solid oxide half-cell, the finger-like pore structure support layer and the dense structure functional support layer are electrode layers, and the dense thin layer induced by the high-temperature interface is the electrolyte layer.

[0013] In step (1), the supporting layer ceramic powder containing electrolyte is selected from a multiphase composite material composed of transition metal oxides or a multiphase composite material composed of transition metal oxides and rare earth metal oxides;

[0014] When the supporting layer ceramic powder containing electrolyte is a multiphase composite material composed of transition metal oxides, the transition metal oxides include NiO, ZnO, Fe 2 O 3 、Co 3 O 4、MnO 2 Two of them, Y 2 O 3 and Sc 2 O 3 One or two of the above, and ZrO 2 ; The electrolyte is one of yttria-stabilized zirconia or scandia-stabilized zirconia, and its molar percentage is 30-80% based on the total molar amount of the supporting layer ceramic powder containing the electrolyte;

[0015] When the supporting layer ceramic powder containing electrolyte is a multiphase composite material composed of transition metal oxide and rare earth metal oxide, the transition metal oxide is NiO, Fe 2 O 3 、ZnO、Co 3 O 4 、MnO 2 The rare earth metal oxide is Gd 2 O 3 , Pr 2 O 3 、Sm 2 O 3 One or two of the following, and CeO 2 The electrolyte is one of praseodymium oxide doped cerium oxide, gadolinium oxide doped cerium oxide and samarium oxide doped cerium oxide, and its molar percentage is 30-80% based on the total molar amount of the supporting layer ceramic powder containing the electrolyte;

[0016] Preferably, the electrolyte thin layer is Y 0.08 Zr 0.92 O 2-δ (YSZ), dense structure functional layer is 60 mol.% Y 0.08 Zr 0.92 O 2-δ and 40mol.%NiFe 2 O 4 (YSZ-NFO); finger-like pore structure support layer is 60 mol.% Y 0.08 Z r0.92 O 2-δ and 40mol.%NiFe 2 O 4 (YSZ-NFO).

[0017] In step (1), the polymer is selected from one or two of polysulfone, polyethersulfone, polyvinylidene fluoride, polyetherimide, and polyvinyl chloride.

[0018] In step (1), the organic solvent is one or two of N,N-dimethylformamide, N-methylpyrrolidone and N,N-dimethylacetamide.

[0019] In step (1), the mass ratio of the polymer, the organic solvent, and the supporting layer ceramic powder containing the electrolyte is 10:35:55.

[0020] In step (2), the non-solvent is selected from water, a polar solvent, and a mixed solvent of water / polar solvent.

[0021] In step (3), the high temperature calcination temperature is 1350-1500°C and the holding time is 3-20h;

[0022] In step (4), the alumina substrate is selected from dense corundum sheets or alumina powder; the temperature of the high-temperature interface induction is 1350-1500°C, and the insulation time is 3-20h.

[0023] The thickness of the finger-like pore structure support layer is 250-500 μm; the thickness of the dense structure functional support layer is 1-30 μm, and the thickness of the dense electrolyte layer is 0.5-5 μm.

[0024] The second aspect of the present invention provides a solid oxide half-cell having an electrolyte thin layer prepared by the above preparation method.

[0025] The beneficial effects of the present invention are:

[0026] 1) The electrolyte layer prepared by the method of the present invention is obtained by interface induction, which saves the steps of screen printing, spraying, chemical deposition and the like in the traditional process, simplifies the process and reduces the cost.

[0027] 2) The thickness of the electrolyte layer in the half-cell prepared by the method of the present invention is easy to control, and the thinnest can reach 5 microns, which can significantly reduce the oxygen ion transmission resistance and improve the battery performance.

[0028] 3) The electrode in the half-cell prepared by the present invention comprises a finger-like structure support layer and a dense structure functional layer. Since the electrolyte thin layer is induced from the dense functional layer, it has strong adhesion to the electrode support layer and is not easy to be delaminated, thereby improving the stability of the battery during long-term operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0030] Figure 1 This is a schematic diagram of the process flow of preparing a solid oxide half-cell with a thin electrolyte layer according to the present invention.

[0031] Figure 2 is a BSEM image of the cross section of the YSZ-NFO / YSZ-NFO / YSZ half-cell prepared in Example 1.

[0032] Figure 3 This is a SEM image of the surface of the YSZ-NFO / YSZ-NFO / YSZ half-cell electrolyte prepared in Example 1.

[0033] Figure 4 It is the AC impedance diagram of the YSZ-NFO / YSZ-NFO / YSZ / Pt full battery prepared in Example 2 at different temperatures. DETAILED DESCRIPTION

[0034] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0035] Example 1: Preparation of a half-cell with a thin YSZ electrolyte layer

[0036] like Figure 1 As shown, NiO, Fe 2 O 3 , Y 2 O 3 and ZrO 2 The oxides are mixed evenly in a stoichiometric ratio of 3:3:0.56:6.44, and then mixed evenly with polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) (the mass ratio of polyvinylidene fluoride, N-methylpyrrolidone, and oxide powder is 10:35:55). The ball-milled oxide powder is dried at 120°C and mixed with the PVDF-NMP solution, and ball-milled for 1000 minutes to obtain a slurry. Then, the slurry is cast on a glass substrate, and after forming, it is placed in water for solvent exchange phase transformation. After 24 hours, the green body is removed from the glass substrate, and after cutting, drying, and shaping, it is heat treated at 1400°C for 10 hours to obtain a pre-calcined body YSZ-NFO. Finally, the pre-calcined body YSZ-NFO is placed on an Al 2 O 3 On the corundum sheet, after high-temperature heat treatment at 1450°C for 10 hours, a YSZ / (YSZ-NFO) / YSZ-NFO half-cell with a YSZ electrolyte thin layer was obtained.

[0037] Figure 2 The cross section of the YSZ / (YSZ-NFO) / YSZ-NFO half-cell shown, the thickness of the YSZ electrolyte layer is 3-4 microns, the thickness of the YSZ-NFO dense functional layer is about 60 microns, and the thickness of the YSZ-NFO finger-like pore structure support layer is about 260 microns; Figure 3 On the electrolyte surface of the YSZ / (YSZ-NFO) / YSZ-NFO half-cell shown, the YSZ grains are adhered and have a high density.

[0038] Example 2: Conductivity of batteries based on YSZ electrolyte thin layers

[0039] The platinum layer was loaded on the electrolyte surface of the YSZ / (YSZ-NFO) / YSZ-NFO half-cell prepared in Example 1 by using an ion sputtering instrument, and then a layer of gold paste was applied. After heat treatment at 900°C for 1 hour, an Au-Pt / YSZ / YSZ-NFO / YSZ-NFO battery was obtained. The AC impedance of the battery at different temperatures was tested in air. Figure 4 As shown, the YSZ-based symmetric battery with a thickness of about 7 microns has a conductivity of about 0.08 S / cm and an ohmic resistance of about 0.35Ω at 800°C, showing excellent conductive properties.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a solid oxide half-cell having a thin electrolyte layer, It is characterized in that The solid oxide half-cell comprises: a finger-like pore structure support layer, a dense structure functional support layer and a dense electrolyte layer; the preparation method comprises the following steps: (1) Mixing a polymer, an organic solvent and a supporting layer ceramic powder containing an electrolyte to prepare a slurry; (2) tape-casting the slurry and immersing it in a non-solvent to obtain an initial green body; (3) After the green body is dried, cut, and shaped, it is calcined at high temperature to obtain a pre-calcined body having a finger-like pore structure and a dense structural functional support layer; (4) placing the pre-calcined body on an alumina substrate, wherein one side of the dense structure functional support layer is in contact with the alumina substrate, and forming a dense thin layer on the surface of the dense structure functional support layer after high temperature interface induction, thereby obtaining a three-layer structure solid oxide half-cell; The supporting layer ceramic powder containing electrolyte is selected from a multiphase composite material composed of transition metal oxides; The transition metal oxides include NiO, ZnO, Fe 2 O 3 、Co 3 O 4 、MnO 2 Two of them, Y 2 O 3 and Sc 2 O 3 One or two of the above, and ZrO 2 ; The electrolyte is one of yttria-stabilized zirconia or scandia-stabilized zirconia, and its molar percentage is 30-80% based on the total molar amount of the supporting layer ceramic powder containing the electrolyte; The electrolyte layer is Y 0.08 Zr 0.92 O 2-δ , the dense structure functional support layer is 60 mol.% Y 0.08 Zr 0.92 O 2-δ and 40mol.% NiFe 2 O 4 ; The finger-like pore structure support layer is 60 mol.% Y 0.08 Z r0.92 O 2-δ and 40 mol.% NiFe 2 O 4 ; In step (1), the polymer is selected from one or two of polysulfone, polyethersulfone, polyvinylidene fluoride, polyetherimide, and polyvinyl chloride; In step (1), the organic solvent is one or two of N,N-dimethylformamide, N-methylpyrrolidone, and N,N-dimethylacetamide; In step (1), the mass ratio of the polymer, the organic solvent, and the supporting layer ceramic powder containing the electrolyte is 10:35:55; The thickness of the finger-like pore structure support layer is 250-500 μm; the thickness of the dense structure functional support layer is 1 - 30 μm, and the thickness of the dense electrolyte layer is 0.5-5 μm; In step (3), the high temperature roasting temperature is 1350-1500°C and the holding time is 3-20 h.

2. The preparation method according to claim 1, It is characterized in that In step (2), the non-solvent is selected from water, a polar solvent, and a mixed solvent of water / polar solvent.

3. The preparation method according to claim 1, It is characterized in that In step (4), the alumina substrate is selected from dense corundum sheets or alumina powder; the temperature of the high-temperature interface induction is 1350-1500°C, and the insulation time is 3-20 hours.

4. A solid oxide half-cell having an electrolyte thin layer prepared according to the preparation method according to any one of claims 1 to 3.

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