CN110676480A

CN110676480A - Porous tubular support body and preparation method thereof, and preparation method of composite cathode support body

Info

Publication number: CN110676480A
Application number: CN201910936369.6A
Authority: CN
Inventors: 李箭; 贾礼超; 颜冬; 蒲健; 池波
Original assignee: Wuhan Huake Fusai New Energy Co Ltd
Current assignee: Wuhan Huake Fusai New Energy Co Ltd
Priority date: 2019-09-29
Filing date: 2019-09-29
Publication date: 2020-01-10

Abstract

The invention relates to the field of solid oxide fuel cells, in particular to a porous tubular support body and a preparation method thereof, and also relates to a preparation method of a composite cathode support body. The porous tubular support body is prepared by uniformly mixing 49-51 parts of YSZ powder, 15-17 parts of pore-forming agent, 3.6-3.7 parts of plasticizer, 4.7-4.9 parts of binder, 2.5-2.8 parts of plasticizer, 0.14-0.18 part of dispersant and 21-23 parts of solvent, adopting a slip casting mode and sintering; the composite cathode support is obtained by preparing a cathode material into a solution, injecting the solution into the porous tubular support by adopting a solution injection method and calcining the solution.

Description

Porous tubular support body and preparation method thereof, and preparation method of composite cathode support body

Technical Field

The invention relates to the technical field of Solid Oxide Fuel Cells (SOFC), in particular to a porous tubular support body and a preparation method thereof, and also relates to a preparation method of a composite cathode support body.

Background

A Solid Oxide Fuel Cell (SOFC) is an energy conversion device that can directly convert chemical energy in fuel into electrical energy, and has many advantages, such as cleanness, no pollution, silence, no noise, and modular design, and the like, and these advantages make the SOFC attract attention and be widely applied to the fields of distributed power stations, transportation, military, and the like. According to different classification methods, the cells can be divided into different types, and according to the difference of components providing mechanical properties, the SOFC can be divided into: metal-supported, anode-supported, electrolyte-supported, and cathode-supported.

The electrolyte-supported battery usually has better strength and stability, and the preparation process is mature, but in the working process, the ohmic impedance generated by the electrolyte support body is larger, so that the whole electrochemical performance of the battery is influenced, if higher output power is required to be obtained, the working temperature of the battery needs to be increased, but the components of the battery are mutually reacted at high temperature, so that the internal resistance of the battery is further increased, and the performance of the battery is attenuated; anode-supported SOFC using H₂When the fuel is used as fuel, the fuel has smaller polarization resistance, but the thermal cycle stability of the anode-supported SOFC electric stack is poorer, and the long-time stable operation cannot be realized in the operation process of the electric stack; the SOFC supported by the cathode or the anode can greatly reduce the thickness of electrolyte and the working temperature of the battery, so that the selection range of materials of each component is wider, the cost is reduced, the thermal stress during the working of the SOFC is reduced, and the stability of the battery in the long-term working process is improved. The SOFC supported by the cathode has better performance in the long-term operation processThe stability of the current Siemens cathode support SOFC electric pile is longer than 10000 hours, and the unique structure determines that the stability has unique advantages. However, the cathode support causes the conductivity to be low and the thickness of the cathode to be large, so that the mass transfer process of the electrode is limited and the output power of the battery is low.

Depending on the different geometries of the cell, SOFCs can be classified as: tubular SOFCs and planar SOFCs. The flat plate type cell is relatively easy to manufacture, the current is collected simply and conveniently, but simultaneously, a large number of sealing planes are difficult to seal the flat plate type cell at high temperature, the tubular SOFC enables the high-temperature sealing of the cell to be easy due to natural structural advantages, meanwhile, the thermal shock resistance of the tubular SOFC in the working process is strong, the damage of a single cell cannot influence the operation of the whole electric pile, and therefore large-scale electric pile assembly is easy to carry out. Cathode supported tube batteries of siemens-westinghouse, usa have been operating cumulatively for tens of thousands of hours.

Disclosure of Invention

The invention provides a porous tubular support body and a preparation method thereof, and simultaneously provides a preparation method of a composite cathode support body, aiming at the technical problems in the prior art.

The technical scheme for solving the technical problems is as follows:

the invention provides a porous tubular support body which comprises the following raw materials in parts by weight: 49-51 parts of YSZ powder, 15-17 parts of pore-forming agent, 3.6-3.7 parts of plasticizer, 4.7-4.9 parts of binder, 2.5-2.8 parts of plasticizer, 0.14-0.18 part of dispersant and 21-23 parts of solvent.

The pore-forming agent can be one or more of starch, carbon powder and graphite, the plasticizer can be one or more of Butyl Benzyl Phthalate (BBP), dimethyl phthalate (DMP) and diethyl phthalate (DEP), the binder can be one or more of polyvinyl butyral (PVB), phenolic resin and polyurethane, the plasticizer can be one or more of polyalkyl glycol (PAG), dibutyl phthalate (DBP) and diethyl phthalate (DEP), the dispersing agent can be one or more of fish oil and polyethylene glycol, and the solvent can be one or two of alcohol and xylene.

In a preferred embodiment of the present invention, the pore-forming agent is starch, and preferably corn starch.

As another preferred technical scheme of the present invention, the porous tubular support provided by the present invention comprises the following raw materials by weight: YSZ 50.34 parts, corn starch 16 parts, butyl benzyl phthalate 3.65 parts, polyvinyl butyral 4.79 parts, polyalkylene glycol 2.69 parts, fish oil 0.16 parts, and alcohol/xylene 22.37 parts.

In the preparation process of the porous YSZ support tube, the addition amount of the pore-forming agent corn starch is crucial, and the content of the pore-forming agent corn starch directly determines the porosity of the support body and the demoulding difficulty of a blank body.

The invention also provides a preparation method of the porous tubular support, which is to uniformly mix various raw materials to prepare support slurry with certain viscosity; preparing the tubular supporting body by a slip casting method, and sintering to obtain the tubular supporting body.

Specifically, the method comprises the following steps: putting various powders and additives into a ball milling tank, and taking out the powders after ball milling is uniform to obtain support body slurry; carrying out vacuum defoaming on the support body slurry; injecting the support body slurry subjected to bubble removal into a plastic test tube by adopting a grouting forming technology, and repeatedly inverting to ensure that the slurry is uniformly coated on the inner wall of the test tube, and pouring the redundant slurry in the test tube out from a tube opening for recycling; blowing and drying the test tube coated with the slurry at 25 ℃, and demolding to obtain a tubular support body 1 with certain strength; the tubular support 1 is sintered.

Wherein the sintering of the tubular support 1 comprises the following three stages, the first stage: slowly heating the tube-type support 1 with certain strength obtained by demoulding to 240 ℃ to remove organic substances in the tube-type support to obtain a support 2; the second stage, embedding the support body 2 in YSZ powder, and pre-burning at 900-1200 ℃ to remove organic matters and pore-forming agents with higher volatilization temperature in the support body 2 to form a loose and porous support body 3; and a third stage: preparing a thin film electrolyte on the surface of the support body 3 by adopting a dipping-pulling method, and slowly heating to 1400 ℃ and 1550 ℃ for sintering and compacting.

The dip-and-pull method is shown in FIG. 2 and comprises the following stages:

immersing: immersing the support body 3 in an electrolyte solution of the coating material at a constant speed (preferably without shaking), the support body 3 being immersed in a plating solution which wets the surface of the support body 3 and adheres to the surface of the support body 3;

deposition: the support body 3 stays in the solution for a period of time, and the coating solution is attached to the surface of the support body 3 to form a wet gel film;

lifting: the substrate is vertically pulled out of the coating solution at a constant speed, the extraction is carried out at the constant speed, any shaking is avoided, the thickness of the coating is determined by the pulling speed (the thicker coating material can be obtained by faster extraction), the stable liquid level is ensured in the process of pulling the coating, the substrate is vertical to the liquid level, and the substrate continuously rises at a constant speed to ensure that a continuous film layer with uniform thickness is formed on the surface of the substrate;

and (3) evaporation: the support 3 was allowed to stand and dried at room temperature to form a thin layer. In the case of volatile solvents, such as alcohols, evaporation already begins during deposition and pulling.

More specifically, the sintering comprises the following stages, namely, the first stage is that the temperature is slowly increased to 200-; and a second stage: the temperature raising procedure of the pre-sintering is directly raising the temperature to 900-; and a third stage: the sintering compact slow temperature rise procedure comprises the steps of slowly raising the temperature to 350 ℃ for 250-plus-materials at first, preserving the heat for 650min for 550-plus-materials, slowly raising the temperature to 1500 ℃ for 350min at intervals for 800-plus-materials at intervals, and then carrying out interval temperature reduction.

The sintering process in the first stage is to degrease the support body 1 to remove organic substances therein to obtain a support body 2; the sintering process of the second stage is to vertically bury the support body 2 in YSZ powder for presintering, so that the battery has certain mechanical property, and simultaneously remove organic matters and pore-forming agents with higher volatilization temperature in the support body 2 to form a loose and porous support body 3; the third stage of sintering process is to sinter and densify after preparing the thin film electrolyte on the surface of the support 3.

The invention also provides a preparation method of the composite cathode support, namely a preparation method of a half cell, which comprises the following steps: preparing the cathode material into a solution, injecting the solution into the prepared porous tubular support body by adopting a solution injection method, and calcining at the temperature of 800-900 ℃.

Wherein the cathode material is LSM or LSCF.

In the invention, YSZ is yttria (Y2O3) stabilized zirconia (ZrO2), LSM is lanthanum strontium manganese, and LSCF is lanthanum strontium cobalt iron.

The invention has the following beneficial technical effects:

(1) according to the porous tubular support body provided by the invention, YSZ is used as an electrolyte, and the porous tubular support body is prepared by reasonably proportioning a pore-forming agent, a plasticizer, a binder, a plasticizer, a dispersant and a solvent and improving a sintering process after research, so that the porous tubular support body is stable in structure, easy to demould, and capable of completely meeting the gas transmission requirement in the SOFC working process, and the porosity of the porous tubular support body can reach more than 30%;

(2) the cathode support body provided by the invention is prepared by injecting a cathode material into a porous tubular support body prepared by taking an electrolyte as a material by adopting a solution injection method and calcining the porous tubular support body, so that the polarization impedance of a cathode can be effectively reduced, and the electrochemical performance of a battery is improved;

(3) the SOFC electrolyte has a sintering temperature higher than 1400 ℃, and in a cathode-supported SOFC, when LSM is used as a cathode material and YSZ is used as an electrolyte, the LSM and YSZ undergo a solid-phase reaction at 1250 ℃ to generate SrZrO₃And La₂Zr₂O₇The two substances generate at the interface of the cathode and the electrolyte and can block the transportation of oxygen ions, so that the electrochemical performance of the battery is reduced, the cathode solution (LSM or LSCF) is injected into the YSZ electrolyte framework by adopting a solution injection method to prepare the LSM-YSZ thin film composite cathode, the solid phase reaction in the high-temperature sintering process is effectively avoided by the cathode structure, the transmission path of electrons is reduced, the polarization impedance of the cathode can be effectively reduced, the electrochemical performance of the battery is improved, and the SOFC can be used for realizing the electrochemical performance reduction of the batterySo as to stably operate for a long time.

Drawings

FIG. 1 is a flow chart of a method of making a tubular support;

FIG. 2 is a process flow diagram of a dip-draw process;

FIG. 3 is a scanning electron microscope scan of porous YSZ and thin film electrolyte after high temperature sintering in example 1;

FIG. 4 is a scanning electron microscope scan of porous YSZ after high temperature sintering in example 4.

Detailed Description

The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.

Example 1

A preparation method of a composite cathode support comprises the following steps:

1. firstly, preparing porous electrolyte support body slurry according to the mixture ratio of table I, putting various powders and additives shown in table I into a ball milling tank, performing ball milling at 300rpm/min for 48h, and taking out.

TABLE proportioning of the porous tubular support slurry of example 1

2. Removing bubbles from the prepared support body slurry in vacuum through a vacuum bubble removing machine, injecting the support body slurry into a 5ml plastic test tube by adopting a grouting forming technology, and repeatedly inverting to ensure that the slurry is uniformly coated on the inner wall of the test tube, and pouring the redundant slurry in the test tube out from a tube opening for recycling; placing the test tube with the inner wall coated with the slurry at a constant temperature of 25 ℃, and carrying out forced air drying; due to the characteristics of the slurry, after the solvent is volatilized, the volume of the slurry shrinks, and the support body 1 with certain strength is obtained by demolding, wherein the specific preparation process is shown in fig. 1.

3. The support 1 contains a large amount of organic additives, the support 1 is degreased to remove organic substances therein to form the support 2, and the temperature rise procedure is as follows:

4. vertically embedding the support body 2 in YSZ powder, presintering at 1050 ℃ to enable the battery to have certain mechanical property, removing organic matters and pore-forming agents with higher volatilization temperature in the support body 2 to form a loose and porous support body 3 for later use, wherein the sintering procedure is as follows:

5. and preparing the YSZ film electrolyte on the surface of the tubular porous YSZ by adopting a dipping-pulling method.

6. The support body 3 with the YSZ film electrolyte prepared on the surface is sintered and compacted at 1500 ℃, and the sintering process is as follows:

7. preparing a cathode material LSM into a 0.03mol/L solution, injecting the solution into the prepared porous tubular support body by adopting a solution injection method, and calcining at 850 ℃ to obtain the tubular support body supported by the composite cathode.

Fig. 3 shows porous YSZ and thin film electrolyte after high temperature calcination.

Example 2

TABLE proportioning of the porous tubular support slurry of example 1

2. Removing bubbles from the prepared support body slurry in vacuum through a vacuum bubble removing machine, injecting the support body slurry into a 5ml plastic test tube by adopting a grouting forming technology, and repeatedly inverting to ensure that the slurry is uniformly coated on the inner wall of the test tube, and pouring the redundant slurry in the test tube out from a tube opening for recycling; placing the test tube with the inner wall coated with the slurry at a constant temperature of 25 ℃, and carrying out forced air drying; due to the characteristics of the slurry, after the solvent is volatilized, the volume of the slurry shrinks, and the support body 1 is obtained by demolding, wherein the specific preparation process is shown in fig. 1. 3. The support 1 contains a large amount of organic additives, the support 1 is degreased to remove organic substances therein to form the support 2, and the temperature rise procedure is as follows:

7. preparing a cathode material LSM into 0.02mol/L solution, injecting the solution into the prepared porous tubular support body by adopting a solution injection method, and calcining at 800 ℃ to obtain the tubular support body supported by the composite cathode.

Example 3

TABLE proportioning of the porous tubular support slurry of example 1

7. preparing a cathode material LSM into 0.05mol/L solution, injecting the solution into the prepared porous tubular support body by adopting a solution injection method, and calcining at 900 ℃ to obtain the tubular support body supported by the composite cathode.

Example 4

Table 4 proportioning of the slurry for the porous tubular support in example 4

In the YSZ slurry mixture ratio shown in table 4, the porosity of the support tube is insufficient due to the low pore-forming agent content, and the support tube cannot perform the gas transmission function, and the cross-sectional morphology of the prepared YSZ support tube is shown in fig. 4. The porosity of the prepared YSZ supporting tube is only 17 percent through the mercury intrusion instrument test, the gas transmission requirement in the SOFC working process cannot be met, and in order to meet the requirement of uniform mixing of YSZ powder and various additives, the addition amount of the solvent is large, so that a large number of cracks appear in the drying process of the green body, and the finished product rate cannot meet the test requirement.

Example 5

TABLE 5 proportioning of the slurries for the porous tubular supports of example 5

3. Removing bubbles from the prepared support body slurry in vacuum through a vacuum bubble removing machine, injecting the support body slurry into a 5ml plastic test tube by adopting a grouting forming technology, and repeatedly inverting to ensure that the slurry is uniformly coated on the inner wall of the test tube, and pouring the redundant slurry in the test tube out from a tube opening for recycling; placing the test tube with the inner wall coated with the slurry at a constant temperature of 25 ℃, and carrying out forced air drying; due to the characteristics of the slurry, after the solvent is volatilized, the volume of the slurry is shrunk, and the demolding is carried out.

The slurry formulations shown in table 5 resulted in the slurry sticking inside the mold during the preparation of the YSZ support, making the green body impossible to demold.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. The porous tubular support body is characterized by comprising the following raw materials, by weight, 49-51 parts of YSZ powder, 15-17 parts of a pore-forming agent, 3.6-3.7 parts of a plasticizer, 4.7-4.9 parts of a binder, 2.5-2.8 parts of a plasticizer, 0.14-0.18 part of a dispersant and 21-23 parts of a solvent.

2. The porous tubular support of claim 1, comprising the following raw materials in parts by weight: 49-51 parts of YSZ, 15-17 parts of starch, 3.6-3.7 parts of plasticizer, 4.7-4.9 parts of binder, 2.5-2.8 parts of plasticizer, 0.14-0.18 part of dispersant and 21-23 parts of solvent.

3. The porous tubular support body of claim 2, comprising the following raw materials in parts by weight: 49-51 parts of YSZ, 15-17 parts of starch, 3.6-3.7 parts of butyl benzyl phthalate, 4.7-4.9 parts of polyvinyl butyral, 2.5-2.8 parts of polyalkylene glycol, 0.14-0.18 part of fish oil and 21-23 parts of alcohol/xylene.

4. The porous tubular support body of claim 3, comprising the following raw materials in parts by weight: YSZ 50.34 parts, corn starch 16 parts, butyl benzyl phthalate 3.65 parts, polyvinyl butyral 4.79 parts, polyalkylene glycol 2.69 parts, fish oil 0.16 parts, and alcohol/xylene 22.37 parts.

5. The method for preparing a porous tubular support according to claim 1, wherein the support slurry having a certain viscosity is prepared by uniformly mixing the raw materials; preparing the tubular supporting body by a slip casting method, and sintering to obtain the tubular supporting body.

6. The method for preparing a porous tubular support according to claim 5, wherein various powders and additives are put into a ball milling tank, and are taken out after being ball milled uniformly to obtain support slurry; carrying out vacuum defoaming on the support body slurry; injecting the support body slurry subjected to bubble removal into a plastic test tube by adopting a grouting forming technology, and repeatedly inverting to uniformly coat the slurry on the inner wall of the test tube; drying the test tube coated with the slurry by blowing air, and demolding to obtain a tubular support body 1 with certain strength; the tubular support 1 is sintered.

7. The method of claim 5, wherein the sintering step comprises three stages,

the first stage, slowly raising the temperature of the tubular support 1 with certain strength obtained by demoulding to 200-300 ℃ to remove most of organic substances to obtain a support 2;

the second stage, embedding the support body 2 in YSZ powder, and pre-burning at 900-1200 ℃ to remove organic matters and pore-forming agents with higher volatilization temperature in the support body 2 to form a loose and porous support body 3;

and a third stage: preparing a thin film electrolyte on the surface of the support body 3 by adopting a dipping-pulling method, and slowly heating to 1400 ℃ and 1550 ℃ for sintering and compacting.

8. The method of claim 7, wherein the sintering step comprises the steps of,

the first stage, the procedure of slowly raising the temperature at intervals is to raise the temperature to 200-;

and a second stage: the temperature raising procedure of the pre-sintering is directly raising the temperature to 900-;

and a third stage: the sintering compact slow temperature rise procedure comprises the steps of slowly raising the temperature to 350 ℃ for 250-plus-materials at first, preserving the heat for 650min for 550-plus-materials, slowly raising the temperature to 1500 ℃ for 350min at intervals for 800-plus-materials at intervals, and then carrying out interval temperature reduction.

9. The preparation method of the composite cathode support is characterized by comprising the following steps of: preparing a cathode material into a solution, injecting the solution into the porous tubular support body in the claim 5 by a solution injection method, and calcining at 800-900 ℃.

10. The method of claim 9, wherein the cathode material is LSM or LSCF.