A method for continuous roll-to-roll aqueous tape casting of solid oxide electrolysis cells

Abstract

The application belongs to the field of solid oxide electrolysis cells, and discloses a method for preparing a solid oxide electrolysis cell by continuous roll-to-roll aqueous flow casting. The method comprises the following steps: mixing an oxygen electrode powder, a barrier layer powder, an electrolyte powder, a hydrogen electrode powder and a support body powder respectively with a dispersant, a binder, a plasticizer, a defoaming agent and a solvent, and defoaming to obtain an aqueous flow casting oxygen electrode slurry, an aqueous flow casting barrier layer slurry, an aqueous flow casting electrolyte slurry, an aqueous flow casting hydrogen electrode slurry and an aqueous flow casting support body slurry respectively; sequentially casting the above slurries to obtain a five-layer thin film green body; and performing integrated devolatilization-sintering heat treatment on the obtained five-layer thin film green body to obtain a solid oxide electrolysis cell. The method is easy to industrialize and implement in roll-to-roll continuous production, avoids the conventional hot pressing, lamination and multi-step sintering process flow, simplifies the preparation process and reduces energy consumption cost, and the prepared solid oxide electrolysis cell has good electrochemical performance.

Description

Technical Field

[0001] The present invention belongs to the field of solid oxide electrolytic cells, and relates to a method for continuously preparing a multilayer film of a solid oxide electrolytic cell, and specifically to a method for preparing a solid oxide electrolytic cell by continuous roll-to-roll aqueous casting. Background Art

[0002] As an all-solid-state energy conversion device, the solid oxide electrolysis cell (SOEC) can convert chemical energy into electrical energy. It boasts high energy conversion efficiency, environmental friendliness, low noise, and strong reliability, making it considered one of the most promising energy conversion devices. Currently commercialized SOECs typically operate at temperatures between 700 and 900°C. These higher operating temperatures promote interactions and diffusion among the cell's components, reducing the cell's lifespan and placing higher demands on the performance of materials such as electrode materials and connectors.

[0003] To improve the market competitiveness of solid oxide electrolyzers (SOECs), it is imperative to reduce the preparation temperature and simplify the preparation process. Hydrogen-electrode-supported electrolyzers are currently more commercially viable. However, the preparation temperature for these electrolyzers is generally above 1300°C to ensure the density of the electrolyte layer. Therefore, higher requirements are placed on the microstructure of the hydrogen electrode support. On the one hand, during high-temperature sintering, the hydrogen electrode side must maintain a good microstructure and a certain porosity to ensure gas and electron transport pathways during the high-temperature water vapor electrolysis reaction. On the other hand, good contact must be achieved between the multilayer thin films of the hydrogen electrode support layer, hydrogen electrode active layer, electrolyte layer, barrier layer, and oxygen electrode layer. Through integrated film formation and sintering processes, effective interfacial contact and mass transfer between the multilayer thin films must be ensured. Furthermore, to ensure a dense electrolyte layer while maintaining the porous and fine structures of the hydrogen and oxygen electrode active layers, internal short circuits and internal friction losses within the electrolyzer must be prevented. This requires the introduction of sintering aids to effectively reduce the densification temperature of the electrolyte layer. This study focuses on the efficient control of the fine structure of the multilayer film in the electrolytic cell and the interface control between the multilayer films, and obtains an efficient and uniform roll-to-roll casting process for preparing multilayer films.

[0004] This paper proposes a relatively simple and easy method that is easy to implement in industrialization. It uses aqueous cast roll-to-roll preparation technology to sequentially cast oxygen electrode film, barrier layer film, electrolyte layer film, hydrogen electrode active layer film and hydrogen electrode support layer film, and finally prepares SOEC monomer electrolytic cell through an integrated debinding-sintering process. Summary of the Invention

[0005] The application aims to avoid the problems of multiple film forming routes, multi-step sintering process and serious organic solvent pollution in the film forming process of solid oxide electrolysis cells, and provides a method for preparing solid oxide electrolysis cells by continuous roll-to-roll aqueous tape casting.

[0006] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0007] A method for preparing solid oxide electrolysis cells by continuous roll-to-roll tape casting, comprising the following steps:

[0008] S1: mixing, defoaming, an oxygen electrode powder, a dispersant, a binder, a plasticizer, a defoaming agent and a solvent to obtain an aqueous tape casting oxygen electrode slurry;

[0009] S2: mixing, defoaming, a barrier layer powder, a dispersant, a binder, a plasticizer, a defoaming agent and a solvent to obtain an aqueous tape casting barrier layer slurry;

[0010] S3: mixing, defoaming, an electrolyte powder, a sintering aid transition metal Fe-MOFs, a dispersant, a binder, a plasticizer, a defoaming agent and a solvent to obtain an aqueous tape casting electrolyte slurry;

[0011] S4: mixing, defoaming, a hydrogen electrode powder, a dispersant, a binder, a plasticizer, a defoaming agent and a solvent to obtain an aqueous tape casting hydrogen electrode slurry;

[0012] S5: mixing, defoaming, a support powder, a dispersant, a binder, a plasticizer, a defoaming agent and a solvent to obtain an aqueous tape casting support slurry;

[0013] S6: sequentially casting the slurry in S1, S2, S3, S4 and S5 to obtain a five-layer thin film green body;

[0014] S7: performing a debinding-sintering integrated heat treatment on the five-layer thin film green body obtained in S6 to obtain a solid oxide electrolysis cell.

[0015] Preferably, the binder in steps S1-S5 is at least one of water-soluble polyvinyl alcohol, water-soluble polyacrylamide and water-soluble polyacrylic acid, and the proportion is 5-10wt% of the powder.

[0016] Preferably, the plasticizer in steps S1-S5 is at least one of polyethylene glycol and glycerol, and the proportion is 5-10wt% of the powder.

[0017] Preferably, the solvent in steps S1-S5 is water.

[0018] Preferably, the Fe-MOFs in step S3 is one of MIL-88(Fe), MIL-53(Fe) and MIL-100(Fe).

[0019] Preferably, the casting in step S6 is a roll-to-roll aqueous casting process, the green body thickness of S1 slurry casting is 20-30 mu m, the green body thickness of S2 slurry casting is 10-20 mu m, the green body thickness of S3 slurry casting is 10-20 mu m, the green body thickness of S4 slurry casting is 10-20 mu m, and the green body thickness of S5 slurry casting is 300-500 mu m.

[0020] Preferably, the integrated debinding-sintering heat treatment process in step S7 is as follows: rising to 150-200 DEG C at a heating rate of 0.5-3 DEG C / min, holding for 0.5-3 hours, then rising to 300-450 DEG C at a heating rate of 0.5-3 DEG C / min, holding for 0.5-3 hours, then rising to 500-700 DEG C at a heating rate of 0.5-3 DEG C / min, holding for 1-2 hours, then rising to 1200-1350 DEG C at a heating rate of 0.5-3 DEG C / min, holding for 3-5 hours at 1200-1350 DEG C.

[0021] Preferably, the oxygen electrode powder in S1 is a mixed powder of LSCF and GDC, and the mass ratio of LSCF to GDC is 1:1.

[0022] The barrier layer powder in S2 is GDC, the electrolyte powder in S3 is 8YSZ powder, and the hydrogen electrode powder in S4 is a mixed powder of NiO and 8YSZ, and the mass ratio of NiO to 8YSZ is 1:1.

[0023] The support layer powder in S5 is a mixed powder of NiO and 3YSZ, and the mass ratio of NiO to 3YSZ is 1:1.

[0024] Preferably, the mixing in S1-S5 is mechanical mixing for 30-60 min, followed by three-roll mixing for 12-48 h.

[0025] A solid oxide electrolysis cell prepared by the above method.

[0026] The present application has the following advantages and beneficial effects:

[0027] 1. In the present application, the green body of the 300-500 mu m thick support body is cast by one-time aqueous casting, and the green body of the five-layer functional film is continuously cast by roll-to-roll continuous production, which is simple in operation, simplifies the SOEC preparation process, avoids the conventional hot pressing, lamination and multi-step sintering process, reduces the energy consumption cost, realizes the co-sintering of the electrolyte, functional layer and electrode, and realizes the close contact between the layers, which is easy to realize and popularize in the solid oxide electrolysis cell.

[0028] 2. The solid oxide electrolysis cell prepared by the present application has good electrochemical performance, and the electrolysis current can reach 30 A under an electrolysis voltage of 1.3 V. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A photo of a solid oxide electrolytic cell supported by a hydrogen electrode prepared in Example 1 of the present invention. The solid oxide electrolytic cell has a geometric size of 10*10 cm. 2 , the effective area of ​​the oxygen electrode is 81cm 2 .

[0030] Figure 2 The electrochemical performance of the solid oxide electrolytic cell prepared in Example 1 is shown in the volt-ampere characteristic curve. At an electrolysis voltage of 1.3 V, the electrolysis current can reach 30 A.

[0031] Figure 3 The microstructure of the hydrogen electrode-supported solid oxide electrolysis cell prepared in Example 1 of the present invention comprises, from bottom to top, an oxygen electrode layer, a barrier layer, a dense electrolyte layer, a hydrogen electrode active layer, and a hydrogen electrode support layer, with each layer being tightly connected.

[0032] Figure 4 The microstructure of the hydrogen electrode-supported solid oxide electrolysis cell prepared in Example 2 of the present invention comprises, from bottom to top, an oxygen electrode layer, a barrier layer, a dense electrolyte layer, a hydrogen electrode active layer, and a hydrogen electrode support layer. The barrier layer and the electrolyte layer have poor contact, resulting in a short circuit inside the electrolysis cell and the inability to electrolyze water vapor. DETAILED DESCRIPTION

[0033] The present invention will be described in further detail below with reference to specific examples, but the embodiments of the present invention are not limited thereto. For process parameters not particularly noted, conventional techniques may be used.

[0034] LSCF, La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ ,

[0035] GDC, gadolinium-doped ceria,

[0036] YSZ, yttria-stabilized zirconia,

[0037] MIL-88(Fe), C 24 H4O 13 Fe3.

[0038] Example 1

[0039] ① Mechanically mix 100g LSCF powder and 100g GDC for 2h to obtain LSCF-GDC oxygen electrode mixed powder

[0040] ② 50g 8YSZ powder, 1g MIL-88(Fe) are mechanically mixed, and Fe-modified 8YSZ powder (Fe-8YSZ) is obtained by annealing at 450°C for 2h

[0041] ③ 100g 8YSZ powder and 100g NiO are mechanically mixed for 2h to obtain NiO-8YSZ hydrogen electrode active layer mixed powder

[0042] ④ 500g 3YSZ powder and 500g NiO are mechanically mixed for 2h to obtain NiO-3YSZ hydrogen electrode support mixed powder

[0043] ⑤ The LSCF-GDC oxygen electrode mixed powder, water-soluble polyacrylic polymer binder, polypropylene dispersant, polyethylene glycol 400 plasticizer, and polyether defoaming agent are mixed in a mass ratio of (1:10%:1%:10%:0.5%), mechanically mixed for 30min, three-roll mixed for 48h, and then deaerated by a vacuum deaerator for 12h to obtain the corresponding oxygen electrode water-based casting slurry;

[0044] ⑥ The GDC barrier layer powder, water-soluble polyacrylic polymer binder, polypropylene dispersant, polyethylene glycol 400 plasticizer, and polyether defoaming agent are mixed in a mass ratio of (1:8%:1%:8%:0.5%), mechanically mixed for 30min, three-roll mixed for 48h, and then deaerated by a vacuum deaerator for 12h to obtain the corresponding barrier layer water-based casting slurry;

[0045] ⑦ The electrolyte powder Fe-8YSZ in ②, water-soluble polyacrylic polymer binder, polypropylene dispersant, polyethylene glycol 400 plasticizer, and polyether defoaming agent are mixed in a mass ratio of (1:10%:1%:10%:0.5%), mechanically mixed for 30min, three-roll mixed for 48h, and then deaerated by a vacuum deaerator for 12h to obtain the corresponding electrolyte water-based casting slurry;

[0046] ⑧ The NiO-8YSZ hydrogen electrode active layer mixed powder in ③, water-soluble polyacrylic polymer binder, polypropylene dispersant, polyethylene glycol 400 plasticizer, and polyether defoaming agent are mixed in a mass ratio of (1:10%:1%:10%:0.5%), mechanically mixed for 30min, three-roll mixed for 48h, and then deaerated by a vacuum deaerator for 12h to obtain the corresponding hydrogen electrode active layer water-based casting slurry;

[0047] ⑨ ④ NiO-3YSZ hydrogen electrode support layer mixed powder, water-soluble polyacrylic acid polymer binder, polypropylene dispersant, polyethylene glycol 400 plasticizer, and polyethyl ether defoamer were mixed in a mass ratio of (1:20%:5%:10%:0.5%), mechanically mixed for 30 minutes, three-roll mixed for 48 hours, and degassed in a vacuum degassing machine for 12 hours to obtain the corresponding hydrogen electrode support layer water-based casting slurry;

[0048] ⑩ The slurry obtained in ⑤ was subjected to a casting machine with a blade height of 80 μm and a casting speed of 0.07 m / min to obtain a 50 μm oxygen electrode green film.

[0049] On the green film obtained at ⑩, the slurry obtained at ⑥ was cast using a casting machine with a blade height of 50 μm and a casting speed of 0.1 m / min to obtain a 25 μm double-layer green film.

[0050] exist On the obtained double-layer green film, the slurry obtained in step ⑦ was cast using a casting machine with a blade height of 50 μm and a casting speed of 0.15 m / min to obtain a 20 μm three-layer green film.

[0051] exist On the obtained three-layer green film, the slurry obtained in ⑧ was cast using a casting machine with a knife height of 80μm and a casting speed of 0.15m / min to obtain a 25μm four-layer green film.

[0052] exist On the obtained four-layer green film, the slurry obtained in ⑨ was cast using a casting machine with a knife height of 500μm and a casting speed of 0.10m / min to obtain a 450μm five-layer green film.

[0053] Steps A five-layer green film was obtained and subjected to integrated heat treatment of binder removal and sintering. The temperature was raised to 200°C at a heating rate of 0.5°C / min and kept at this temperature for 3 hours. Then, the temperature was raised to 450°C at a heating rate of 0.5°C / min and kept at this temperature for 3 hours. Then, the temperature was raised to 500°C at a heating rate of 0.5°C / min and kept at this temperature for 2 hours. Then, the temperature was raised to 1200°C at a heating rate of 0.5°C / min and kept at this temperature for 5 hours. A flat solid oxide electrolytic cell was obtained. Figure 1 , Actual picture of electrolytic cell, geometric size 100cm 2 The effective active area, that is, the area covered by the oxygen electrode, is 81 cm 2 .

[0054] right The obtained electrolytic cell was subjected to electrochemical performance test of high-temperature electrolysis of water vapor. At a test temperature of 750℃, a gold ring was used as a sealing member, a mixed gas with a volume of 450sccm H2O and 50sccm H2 was introduced into the hydrogen electrode side, and air with a volume of 1500sccm was introduced into the oxygen electrode side. When a voltage of 1.3V was applied, the electrolysis current could reach 30A. As shown in FIG. 1, the ordinate is the voltage applied to the electrolytic cell, and the abscissa is the corresponding electrolysis current. Figure 2

[0055] The electrolytic cell after the test was subjected to cross-section scanning electron microscope analysis, as shown in FIG. 2. From top to bottom, they are the oxygen electrode layer, the barrier layer, the dense electrolyte layer, the hydrogen electrode active layer, and the hydrogen electrode support layer. As can be seen from the figure, the film thickness of the barrier layer is 4μm, the thickness of the electrolyte film is 11μm, and the thickness of the hydrogen electrode active layer is 7μm. The layers are in close contact with each other, which is conducive to the electrochemical process. Figure 3 The electrolytic cell after the test was subjected to cross-section scanning electron microscope analysis, as shown in FIG. 2. From top to bottom, they are the oxygen electrode layer, the barrier layer, the dense electrolyte layer, the hydrogen electrode active layer, and the hydrogen electrode support layer. As can be seen from the figure, the film thickness of the barrier layer is 4μm, the thickness of the electrolyte film is 11μm, and the thickness of the hydrogen electrode active layer is 7μm. The layers are in close contact with each other, which is conducive to the electrochemical process.

[0056] Example 2

[0057] Different from Example 1, five-layer green films were obtained, and the degreasing-sintering integrated heat treatment was performed. The temperature was raised to 1200℃ at a rate of 0.5℃ / min, and the temperature was kept at 1200℃ for 5 hours. The cross-section scanning electron microscope analysis of the obtained solid oxide electrolytic cell is shown in FIG. 3. From top to bottom, they are the oxygen electrode layer, the barrier layer, the dense electrolyte layer, the hydrogen electrode active layer, and the hydrogen electrode support layer. As can be seen from the figure, there are large pores between the barrier layer and the electrolyte layer film, the internal structure of the electrolytic cell is broken, and the electrochemical process cannot proceed normally. Figure 4

[0058] The above-mentioned Example 1 is a preferred embodiment of the present application, but the embodiments of the present application are not limited by the above-mentioned examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement methods, which are all included in the protection scope of the present application.​​​

Claims

1. A method for preparing a solid oxide electrolytic cell by roll-to-roll continuous casting, characterized in that: The following steps are involved: S1: mixing oxygen electrode powder, dispersant, binder, plasticizer, defoamer and solvent, and degassing to obtain water-based tape-cast oxygen electrode slurry; S2: mixing and degassing the barrier layer powder, dispersant, binder, plasticizer, defoamer and solvent to obtain a water-based cast barrier layer slurry; S3: mixing the electrolyte powder, sintering aid transition metal Fe-MOFs, dispersant, binder, plasticizer, defoamer and solvent, and degassing to obtain a water-based tape-cast electrolyte slurry; S4: mixing the hydrogen electrode powder, dispersant, binder, plasticizer, defoamer and solvent, and degassing to obtain a water-based cast hydrogen electrode slurry; S5: mixing the support powder, dispersant, binder, plasticizer, defoamer and solvent, and degassing to obtain a water-based casting support slurry; S6: Casting the slurries in S1, S2, S3, S4, and S5 in sequence to obtain a five-layer film green body; S7: performing a debinding-sintering integrated heat treatment on the five-layer film green body obtained in S6 to obtain a solid oxide electrolytic cell; The oxygen electrode powder in S1 is a mixed powder of LSCF and GDC, the barrier layer powder in S2 is GDC, the electrolyte powder in S3 is 8YSZ powder, the hydrogen electrode powder in S4 is a mixed powder of NiO and 8YSZ, and the support layer powder in S5 is a mixed powder of NiO and 3YSZ; The binder in steps S1-S5 is at least one of water-soluble polyvinyl alcohol, water-soluble polyacrylamide, and water-soluble polyacrylic acid, and the proportion thereof is 5-10wt% of the powder; The solvent in steps S1-S5 is water; The Fe-MOFs in step S3 is one of MIL-88(Fe), MIL-53(Fe), and MIL-100(Fe); The casting in step S6 is a roll-to-roll water-based casting process, with the green body thickness of S1 slurry casting being 20-30 μm, the green body thickness of S2 slurry casting being 10-20 μm, the green body thickness of S3 slurry casting being 10-20 μm, the green body thickness of S4 slurry casting being 10-20 μm, and the green body thickness of S5 slurry casting being 300-500 μm; The debinding and sintering integrated heat treatment process described in step S7 is as follows: heating to 150-200°C at a heating rate of 0.5-3°C / min, keeping warm for 0.5-3 hours, then heating to 300-450°C at a heating rate of 0.5-3°C / min, keeping warm for 0.5-3 hours, then heating to 500-700°C at a heating rate of 0.5-3°C / min, keeping warm for 1-2 hours, then heating to 1200-1350°C at a heating rate of 0.5-3°C / min, and keeping warm at 1200-1350°C for 3-5 hours.

2. The method for preparing a solid oxide electrolytic cell by roll-to-roll continuous casting according to claim 1, characterized in that: The plasticizer in steps S1-S5 is at least one of polyethylene glycol and glycerol, and the proportion is 5-10wt% of the powder.

3. The method for preparing a solid oxide electrolytic cell by roll-to-roll continuous casting according to claim 1, characterized in that: The mixing in S1 to S5 is first mechanically mixed for 30 minutes to 60 minutes, and then three-roller mixed for 12 hours to 48 hours.

4. A solid oxide electrolytic cell prepared according to the method according to any one of claims 1 to 3.

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