JP2008010191A - Sealing material and solid oxide fuel cell using sealing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing material for a solid oxide fuel cell having high insulating property and high sealing capability. <P>SOLUTION: The sealing material for the solid oxide fuel cell contains alkali metal-containing amorphous silica particles. The alkali metal-containing amorphous silica particles contain alkali metal-containing silica particles having an alkali metal content, which is a molar ratio of alkali metal/Si, of 0.40-0.85. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sealing material, a solid oxide fuel cell sealed with the sealing material, and a method for manufacturing the sealing material.

As gas sealing materials that are used in a temperature range of 500 ° C. or higher and 800 ° C. or lower and have high insulation properties, glass such as soda glass and mica and ceramic-based sealing materials have been studied (Patent Document 1). Further, a liquid sealing material mainly composed of water glass or the like has been studied (Patent Document 2). On the other hand, a method for synthesizing sodium-containing monodispersed spherical particles has been reported (Non-Patent Document 1).
JP 2004-39573 A JP 2001-319670 A S. Suda, et al., J. Non-Cryst. Solids, 321, 3-9 (2003)

  However, since glass and ceramics-based sealing materials have poor flexibility, it has been difficult to seal a substrate having irregularities on the surface. In particular, soda glass has a problem that it has a relatively high conductivity at a high temperature, and further, there is a problem that a crack occurs at around 500 ° C. and the sealing property is impaired. In addition, there is a problem in sealing performance for a sealing material made of mica or crystal glass. Furthermore, with liquid sealing materials such as adhesives, there is no problem with sealing to a dense base material, but for porous base materials, the sealing performance is maintained because of penetration of the liquid sealing material into the base material. was difficult. Therefore, until now, there has not been obtained a sealing material that has high insulating properties and high sealing properties, or a material that has excellent sealing properties for porous substrates. On the other hand, a method for synthesizing sodium-containing monodispersed spherical particles has been reported, but no application of such spherical particles to an insulating sealing material at a high temperature has been reported.

  Accordingly, it is an object of the present invention to provide a sealing material having high insulation and sealing properties, a method for manufacturing the same, and a sealing structure for a solid oxide fuel cell. Another object of the present invention is to provide a sealing material having an excellent sealing property for a porous substrate, a method for producing the same, and a sealing structure for a solid oxide fuel cell.

  The inventors of the present invention have studied to solve the above-mentioned problems, and have found a sealing material that can realize sealing properties and insulating properties at about 500 ° C. or higher and 800 ° C. or lower. Furthermore, the present inventors have found that it is possible to provide a sealing material that can sufficiently cope with a multi-material substrate by controlling the meltability of the sealing material. The present invention provides the following means based on these findings.

  According to the present invention, there is provided a sealing material containing alkali metal-containing amorphous silica particles. The seal material is preferably a seal material in an environment of 500 ° C. or higher and 800 ° C. or lower, and more preferably for a solid oxide fuel cell having such an operating temperature.

  In the present sealing material, the alkali metal-containing amorphous silica particles can include alkali metal-containing silica particles having an alkali metal / Si molar ratio of 0.40 or more and 0.85 or less. . The alkali metal-containing amorphous silica particles include a first alkali metal-containing amorphous silica particle having a first alkali metal content and a second alkali metal having a smaller content than the first alkali metal content. Content of the second alkali metal-containing amorphous silica particles. In this aspect, the first alkali metal content of the first alkali metal-containing amorphous silica particles can be 0.40 or more and 0.85 or less, and the second alkali metal-containing amorphous silica can be used. The second alkali metal content of the silica particles can be less than 0.40. In particular, the alkali metal content of the first alkali metal-containing amorphous silica particles is 0.50 or more and 0.80 or less, and the alkali metal content of the second alkali metal-containing amorphous silica particles is , 0.20 or less is preferable.

  In the present sealing material, the alkali metal preferably contains sodium. Further, the sealing material can be any one selected from a molded body, powder, slurry, sol, and gel, and the sealing material can be a humidified sheet molded body.

  According to the present invention, there is provided a method for producing a sealing material, comprising: preparing alkali metal-containing amorphous silica particles; and preparing a sealing material containing the alkali metal-containing amorphous silica particles. A manufacturing method is provided. In this case, the preparation step may be a step of preparing any one selected from a molded body, powder, slurry, sol and gel as the sealing material. Moreover, the said preparation process can be made into the process of shape | molding and drying a sheet molded body as the said sealing material, and humidifying the said sheet molded body after drying to make the sheet molded body which has a light transmittance. In this embodiment, the humidification can be performed at a temperature of 10 ° C. or more and 50 ° C. or less and a relative humidity of 70% or more. The alkali metal-containing amorphous silica particles may include alkali metal-containing amorphous silica particles having an alkali metal content of 0.40 or more and 0.85 or less, which is an alkali metal / Si molar ratio.

  The alkali metal-containing amorphous silica particles include a first alkali metal-containing amorphous silica particle having a first alkali metal content and a second alkali metal having a smaller content than the first alkali metal content. Content of the second alkali metal-containing amorphous silica particles.

  According to this invention, it is a solid oxide fuel cell (SOFC), Comprising: The battery provided with the sealing site | part by the sealing material in any one of the said is provided. In the solid oxide fuel cell of the present invention, the sealing material may be a solid oxide fuel cell that seals the multi-material substrate of the solid oxide fuel cell.

  The sealing material of the present invention contains alkali metal-containing amorphous silica particles. By using the alkali metal-containing amorphous silica particles, a sealing material having appropriate meltability (sealability) and insulation is provided. In particular, sealing properties and insulating properties at about 500 ° C. or higher and 800 ° C. or lower can be expressed. Therefore, it can be used as a sealing material in a solid oxide fuel cell having such an operating temperature. Moreover, by using the alkali metal-containing amorphous silica particles having different alkali metal contents, it is possible to develop a sealing property that can sufficiently cope with a polycrystalline substrate by further controlling the meltability. Furthermore, according to the sealing material of the present invention, it is possible to obtain a sealing material having viscosity, plasticity, flexibility or flexibility that can easily follow the unevenness of the surface to be sealed by being humidified. In addition, it is possible to suppress the amount of carbon deposited at the time of melting derived from the organic binder material that may be used for the alkali metal-containing amorphous silica particles and the sealing material. The deposition of carbon lowers the insulating property and also significantly reduces the sealing property. However, according to the sealing material of the present invention, the sealing material in which the deterioration of the insulating property and the sealing property due to the carbon deposition are suppressed can be obtained. Can be provided. Hereinafter, embodiments of the present invention will be described in detail.

(Seal material)
The sealing material of this invention is excellent in the sealing performance in the environment of 500 degreeC or more and 800 degrees C or less, and can be used as a sealing material for such temperature environment. More preferably, it is 500 degreeC or more and 750 degrees C or less. Therefore, it is preferably applied to a solid oxide fuel cell (SOFC) having such a temperature range as an operating temperature range. The applied SOFC includes all forms such as a cylindrical type, a self-supporting type, a supporting membrane type, and an integral laminated type in addition to a flat plate type. The sealing material of the present invention can seal, for example, sealing sites such as between SOFC separators, between a battery and a separator, and between electrodes that are fuel electrodes and air electrodes. In particular, in the case of a sealing material containing silica particles having different alkali metal contents as described later, as a sealing material for a porous substrate such as an electrode, preferably a porous substrate having a porosity of about 20% or more preferable. The porous substrate preferably has a porosity of 30% or more.

(Seal composition)
The sealing material of the present invention contains alkali metal-containing amorphous silica particles. The alkali metal may be one or more selected from alkali metals such as lithium, potassium, sodium and rubidium. In consideration of the melting temperature of the sealing material for exerting the sealing properties, it is preferable to contain sodium. The form of the alkali metal-containing amorphous silica particles is not particularly limited, such as a spherical shape, an indefinite shape, or a flake shape, but is preferably a spherical shape. This is because when it is spherical, a slurry having excellent fluidity can be synthesized when mixed with a binder or the like. Moreover, it is preferable that the average particle diameter of an alkali metal containing silica particle is 0.1 micrometer or more and 0.8 micrometer or less. This is because, within this range, alkali metal-containing amorphous silica particles having a uniform particle diameter can be synthesized. Further, when the particle size is less than 0.1 μm, the particles are aggregated and it is difficult to synthesize monodispersed spherical particles, and when the particle size is 0.8 μm or more, the particle size distribution becomes wide or bimodal. The average particle diameter can be measured with a scanning electron microscope.

  The method for synthesizing the alkali metal-containing amorphous silica particles is not particularly limited, but the sol-gel method described in S. Suda, et al., J. Non-Cryst. Solids, 321, 3-9 (2003) or similar thereto. Can be used. For example, an ethanol solution of a metal alkoxide such as tetraethylorthosilicate (TEOS) or a mixture of a polymer ethanol solution such as hydroxypropylcellulose (HPC) as a dispersant to the ethanol solution as necessary is stirred. While adding an ethanol / water mixture of NaOH to cause a condensation reaction, an organic solvent such as ethanol is added as appropriate to solid-liquid separation, and then the solid content is dried to obtain alkali metal-containing amorphous silica particles. Obtainable. The alkali metal-containing amorphous silica particles thus obtained has a characteristic that the alkali metal can be homogeneously contained in the amorphous silica particles. In the alkali metal-containing amorphous silica particles, the alkali metal content (alkali metal / Si molar ratio) is in the range of 0 to 0.85, more preferably in the range of 0 to 0.75. Can be adjusted. The melting temperature can be adjusted by the alkali metal content. For example, the higher the sodium content, the lower the melting temperature. Further, when the sodium content is increased, the insulating properties of the seal are lowered.

  As the alkali metal-containing amorphous silica particles, alkali metal-containing amorphous silica particles having a single alkali metal in the particles may be used, or two or more alkali metals may be contained in one particle. Crystalline silica particles may be used, or mixed particles containing two or more kinds of alkali metals in different particles may be used.

  The alkali metal / Si molar ratio in the alkali metal-containing amorphous silica particles can be 0.85 or less. This is because homogeneous amorphous silica particles can be synthesized within this range, and when it exceeds 0.85, alkali metal salts are deposited on the surface of the amorphous silica particles and other portions. More preferably, it is 0.75 or less. When using alkali metal-containing amorphous silica particles having the same concentration, the alkali metal / Si molar ratio is preferably 0.40 or more.

  In addition, amorphous silica particles having different alkali metal contents can be used. By using amorphous silica particles having different alkali metal contents, the melting temperature can be easily adjusted, and the silica particles having different alkali metal contents come into contact with each other in the high concentration alkali metal-containing amorphous silica particles. By reducing the melting temperature locally by reacting the alkali metal with silicon dioxide of low-concentration alkali metal-containing amorphous silica particles and melting only the latter surface and the vicinity of the surface, for example, to a porous substrate On the other hand, a filler and a molten material can be provided.

  The sealing material is preferably capable of exhibiting a function as a filler for a porous substrate, and preferably capable of exhibiting a function as a melting material for a dense substrate. For the porous base material, it is preferable to apply a sealing material having a relatively low alkali metal concentration (using few alkali metal-containing amorphous silica particles or using low-concentration alkali metal-containing amorphous silica particles). It is preferable to apply a sealing material having a high alkali metal concentration (a large amount of alkali metal-containing amorphous silica particles or using high concentration alkali metal-containing amorphous silica particles) to the substrate. Moreover, when sealing between a porous base material and a dense base material, it can be set as the sealing material which combined these. That is, a gradient composition with respect to the alkali metal concentration may be obtained by laminating sheet bodies having different concentrations.

  When using amorphous silica particles having different alkali metal contents, alkali metal-containing amorphous silica particles having at least an alkali metal content of 0.40 or more and 0.85 or less, and an alkali metal content of less than 0.40 It preferably contains certain alkali metal-containing amorphous silica particles. These two concentrations of alkali metal-containing amorphous silica particles can be included, which can cause a large local change in melting temperature. Preferably, the high concentration alkali metal-containing amorphous silica particles have an alkali metal content of 0.50 or more, and more preferably 0.60 or more. The alkali metal content of the low-concentration alkali metal-containing amorphous silica particles is 0.20 or less, more preferably 0. In a preferred combination, the alkali metal content of the high-concentration amorphous alkali metal-containing silica particles is about 0.60, and the metal content of the low-concentration alkali metal-containing amorphous silica particles is zero.

  The blending ratio of the high concentration alkali metal-containing amorphous silica particles and the low concentration alkali metal-containing amorphous silica particles can be set according to the melting performance to be obtained. The low concentration alkali metal-containing amorphous silica particles are preferably blended in the range of 20% by volume to 60% by volume with respect to the total amount of the containing amorphous silica particles. The blending ratio is particularly preferable when the alkali metal is sodium.

(Form of sealing material)
The SOFC sealing material of the present invention can take various forms. That is, a molded body such as a sheet molded body molded containing such alkali metal-containing amorphous silica particles, a powder containing alkali metal-containing amorphous silica particles, a slurry containing alkali metal-containing amorphous silica particles, an alkali Examples include a sol containing metal-containing amorphous silica particles, a gel containing alkali metal-containing amorphous silica particles, and a paste containing alkali metal-containing amorphous silica particles. Such various forms of sealing material may be composed of only alkali metal-containing silica particles, or may be composed of an appropriate medium, binder, or the like. For example, water, alcohol such as ethanol, polyethylene glycol (PEG), ether, and a mixture of two or more of these can be used as the medium. Moreover, as a binder, polyvinyl alcohol (PVA), polyvinyl butyral (PVB), etc. can be used. Of these, the use of PVB is preferable from the viewpoint of the concentration of amorphous silica particles contained in a sealing material such as a sheet molded body obtained and the flexibility of the sheet molded body.

(Humidification treatment)
It is preferable that the sealing material has been humidified. The humidification treatment here can be carried out by holding the sealing material in a high humidity atmosphere. The high humidity atmosphere is, for example, a relative humidity of 70% or higher, preferably 80% or higher, more preferably 90% or higher. This is because if it is 70% or more, water can be sufficiently supplied to the sealing material. The temperature is preferably 10 ° C. or higher and 50 ° C. or lower. This is because the water supply rate is easily controlled within this range. Moreover, although the humidification processing time is not particularly limited, it can be about 3 hours or more and 40 hours or less, and most is about 20 hours.

  Although not restricting the present invention, the residual alkoxyl group contained in the sealing material is hydrolyzed by the humidification treatment to generate an alcohol and a silanol group, and a polymerization reaction between the silanol groups or between the silanol groups and other components Is considered to progress. According to the humidification treatment, it is possible to improve the viscosity, plasticity or flexibility of the sealing material, and improve the insulation and sealing properties. The improvement in viscosity, plasticity or flexibility is presumed to be due to the acceleration of the polymerization reaction, and the improvement in insulation and sealing properties is due to the progress of the hydrolysis reaction due to the humidification treatment, so that amorphous silica is contained in the sealing material. It is presumed that the carbon (for example, the alkyl group in the remaining alkoxyl group) derived from the particles, the binder, the medium, or the like can be easily discharged and removed from the sealing material at the time of melting as carbon dioxide. In addition, it is thought that the light transmittance of the sealing material is improved by the humidification treatment because the polymerization reaction of the amorphous silica particles proceeds.

  It is preferable to perform the degree of the humidification treatment to such an extent that the sealing material is provided with light transmittance. When the humidification treatment is such that the sealing material does not have optical transparency, the plasticity and the like are not improved, and carbon is liable to be precipitated at the time of melting, and problems in insulation and sealing properties are likely to occur. Further, if the humidification process is over, the sealing material is wetted and the sheet material is deteriorated. In particular, the viscosity, plasticity, or flexibility of the sealing material can be improved by humidifying the sealing material containing the binder, and the sealing material with improved adhesion and applicability to the seal portion can be obtained. Moreover, in order to clarify the degree of the humidification treatment, a known moisture indicator used for silica can be contained.

  The humidification treatment can be applied to all forms of sealing materials. In the case of an indeterminate shape, viscosity, plasticity, flexibility and the like are improved, and in the case of a sheet shape, the flexibility and flexibility are improved. A preferable form of the sealing material for performing the humidification treatment is a form including a binder, and specifically, a molded body such as a sheet molded body, a paste, a slurry, and the like can be given. That is, it can be set as a humidified molded body or a humidified paste. From the viewpoint of uniform humidification, a molded body having a constant thickness such as a sheet molded body is preferable.

(Manufacturing method of sealing material)
The method for producing a sealing material of the present invention includes a step of preparing alkali metal-containing amorphous silica particles and a step of preparing a sealing material containing alkali metal-containing amorphous silica particles. The step of preparing alkali metal-containing amorphous silica particles may be a step of synthesizing alkali metal-containing amorphous silica particles, or a step of obtaining alkali metal-containing amorphous silica particles by a method other than synthesis. There may be.

  The preparation of the sealing material containing the alkali metal-containing amorphous silica particles varies depending on the various forms of the sealing material described above. In the case of a molded body such as a sheet molded body, it can be obtained by mixing alkali metal-containing amorphous silica particles with an appropriate binder and medium, etc., forming a sheet as a slurry with a doctor blade, and drying. The three-dimensional form and secondary form provided by molding are arbitrary. Further, in the case of powder, it can be obtained by mixing together with an appropriate base material or only alkali metal-containing amorphous silica particles if necessary. The slurry can be obtained by mixing together with alkali metal-containing amorphous silica particles and a suitable slurry substrate or medium. The sol can be obtained by dispersing alkali metal-containing amorphous silica particles having an appropriate particle size in a medium, and the gel can be obtained by drying such a sol.

  About a molded object, a paste, slurry, etc., it can dry suitably and can perform a humidification process after that. The humidification process is as already described. Such humidification processing may be performed on the spot when the SOFC seal structure is constructed, as will be described later.

(Method for producing SOFC sealed with this sealing material and method for sealing SOFC)
The SOFC manufacturing method of the present invention and the SOFC sealing method using the sealing material of the present invention include a step of supplying a sealing material to a sealing portion of the SOFC, and melting the supplied sealing material to seal the sealing portion. And a process.

  First, when the SOFC unit cell is constructed and stacked, the sealing material of the present invention is supplied to a place where a seal is required (seal part). If the sealing material of this invention is a sheet molded object, it can be made to contact | adhere or pinch | interpose along a seal | sticker site | part. In the case of a fluid form such as a paste, slurry, gel, or sol, coating or the like can be employed. It is also possible to spray by lowering the viscosity. Moreover, what is necessary is just to give by methods, such as application | coating and spraying, after making into a suspension form and another fluid form in the case of a powder form. In the case of a sealing material in the form of a molded body or a paste, a humidified body that has been appropriately humidified in advance can be supplied to the seal site. However, after being supplied to the seal site, it may be humidified on the spot. .

  As described above, it is preferable to supply a sealing material using amorphous silica particles containing alkali metal at different concentrations at the sealing site of a porous substrate such as an electrode. By supplying such a sealing material and melting and sealing it in a subsequent step, it is possible to prevent the sealing material from excessively penetrating into the porous base material and to generate voids (pores having a diameter of 10 μm or more) in the sealing portion. Can be sealed. In particular, it is effective to apply to a seal portion in a porous electrode having a porosity of 20% or more, more preferably 30% or more.

  Thereafter, the SOFC is heat-treated at a temperature of 500 ° C. or higher and 800 ° C. or lower, whereby the sealing material is wholly or partially melted to seal the sealing portion. This heat treatment may be performed during the operation of the SOFC, or may be performed as a separate heat treatment prior to the operation of the SOFC. Through the above steps, the SOFC sealed with the present sealing material can be obtained.

  According to the production method and the sealing method of the present invention, particularly by using a humidified body or performing an in-situ humidification process, the deposition of carbon is suppressed, and a seal excellent in insulation and sealability is achieved. be able to.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to this.

(Preparation of sodium-containing amorphous silica particles)
As a precursor of a sheet molded article that melts at 800 ° C. or lower, it contains sodium according to the method described in S. Suda, et al., J. Non-Cryst. Solids, 321, 3-9 (2003). Amorphous silica spherical particles (NS particles) were synthesized by the sol-gel method. Specifically, TEOS (37.295 g) and 0.3 vol% HPC alcohol solution (309.093 g) were mixed to prepare a mixed solution A, and 10M NaOH aqueous solution (19.240 g), ethanol (308.040 g) and water (16.257 g) were mixed. Thus, a mixed solution B was prepared. The mixture A was stirred in warm water at 50 ° C. for 30 minutes, and the mixture B was gradually added dropwise over 1 hour. Then, it was left to cool at room temperature for 30 minutes. Half of each mixture after cooling was centrifuged at 4000 rpm (20 g) for 30 minutes, the supernatant was removed, 200 ml of ethanol was added to the centrifuge precipitate, and further centrifuged at 4000 rpm for 30 minutes. The centrifuge deposit from which the liquid was removed was transferred to a beaker, dried overnight in a hot air dryer at 70 ° C., and further dried overnight in a vacuum dryer at 70 ° C. Thereafter, the dried product was crushed with an agate mortar to obtain amorphous silica particles having a charged Na / Si ratio of 0.8. In addition, except for changing the mixing ratio of the mixed liquid A and the mixed liquid B so that the charged Na / Si ratio becomes 0, 0.6, and 1.0, the respective charged ratios are determined in the same manner as described above. Crystalline silica particles were prepared. FIG. 1 shows the charged composition and each particle shape.

  The composition of each synthesized amorphous silica particle was analyzed by EDS. FIG. 2 shows the relationship between the charged composition and the analysis result of the composition. As shown in FIG. 2, according to the above method, it was found that sodium can be introduced into the particles up to a maximum of about Na / Si = 0.7.

  Next, a sheet compact was produced using amorphous silica particles (NS0.8) having a charging composition of Na / Si = 0.8 (actual Na / Si ratio is about 0.6). That is, a solvent (ethanol and 3-methoxy-1-butanol), a binder (polyvinyl butyral), a dispersant (maleic anhydride), and the like were added to the amorphous silica particles, and were prepared using a doctor blade method. Further, a sheet molded body dried at 60 to 80 ° C. (dried body) and a post-drying post-treatment kept in a high humidity atmosphere at room temperature (relative humidity 98%) for 4 hours (humidified body) were prepared. These were compared. Further, these sheet molded bodies were melted at 800 ° C., and the states after melting were compared.

  By comparing the two sheet molded bodies, it was found that the humidified body that was humidified in a high-humidity atmosphere became transparent and improved in flexibility and flexibility. As for the humidification time, if it is too short, the transparency is incomplete and the carbon is likely to precipitate, and if it is too long, the sheet material is deteriorated. Further, from the result of melting at 800 ° C. in room temperature, it was found that the dried product was blackened and a large amount of carbon remained. On the other hand, it was revealed that the humidified body had a transparent molten state and maintained sufficient insulation. When the amount of carbon remaining in these samples was analyzed by a carbon analyzer, C / Si = 0.049 in the dry body and C / Si = 0 which is 1/3 or less in the humidified body. .015. When a large amount of carbon is deposited, the sealing performance becomes a major obstacle. Accordingly, it has been found that by appropriately performing post-treatment such as a humidified body, a sealing material that does not cause carbon deposition and retains sealing properties and insulation properties can be synthesized.

  When the humidified body prepared in “Example 1” was supplied to a porous base material having a porosity of 30% or more and melt-treated in the same manner, the sealing material penetrated into the porous base material and air bubbles were generated in the sealing part. (See FIG. 3A). Therefore, NS0.8 silica particles were mixed with particles not containing sodium (NS 0.0 particles) so as to be 20 mass% or more and 30 mass% or less as a whole to obtain a sheet molded body, and then humidified. FIG. 3B shows the result of evaluating the sealing performance of the humidified body thus obtained with an SEM photograph. As shown in FIG.3 (b), it turned out that according to such a humidification process body, sufficient sealing performance can be expressed even if it is a porous base material. In addition, NS0.8 silica particles and NS0.0 silica particles are not limited to merely dispersing inert particles, but the sodium in NS0.8 particles reacts with NS0.0 silica particles to react locally. It has been found that there is an effect of changing the melting temperature.

The figure which shows the preparation composition in Example 1, and each particle shape. The figure which shows the relationship between the preparation composition and the analysis result of a composition. The figure which shows the result ((a) and (b)) which evaluated the sealing performance with respect to a porous base material in Example 2 by SEM.

Claims (17)

  A sealing material containing alkali metal-containing amorphous silica particles.   2. The sealing material according to claim 1, wherein the alkali metal-containing amorphous silica particles include alkali metal-containing silica particles having an alkali metal / Si molar ratio of 0.40 or more and 0.85 or less. .   The alkali metal-containing amorphous silica particles include a first alkali metal-containing silica particle having a first alkali metal content and a second alkali metal-containing second less than the first alkali metal content. The sealing material according to claim 1 or 2, comprising the alkali metal-containing silica particles.   The sealing material according to claim 3, wherein the first alkali metal content of the first alkali metal-containing amorphous silica particles is 0.40 or more and 0.85 or less.   The sealing material according to claim 3 or 4, wherein the second alkali metal content of the second alkali metal-containing amorphous silica particles is less than 0.40.   The alkali metal content of the first alkali metal-containing amorphous silica particles is 0.50 or more and 0.85 or less, and the alkali metal content of the second alkali metal-containing amorphous silica particles is 0. The sealing material according to claim 3, which is 20 or less.   The sealing material according to claim 1, wherein the alkali metal contains sodium.   The sealing material according to any one of claims 1 to 7, wherein the sealing material is any one selected from a molded body, powder, slurry, paste, sol, and gel.   The sealing material according to any one of claims 1 to 7, wherein the sealing material is a humidified binder-containing sheet molded body. A method of manufacturing a sealing material,
Preparing alkali metal-containing amorphous silica particles;
Preparing a sealing material containing the alkali metal-containing amorphous silica particles;
Manufacturing method.   The manufacturing method according to claim 10, wherein the preparation step is a step of preparing any one selected from a molded body, powder, slurry, paste, sol, and gel as the sealing material.   The said preparation process is a process of shape | molding a sheet molded object as the said sealing material, drying, humidifying the said sheet molded object after drying, and setting it as the sheet molded object which has a light transmittance. Production method.   The manufacturing method according to claim 12, wherein the humidification is performed at a temperature of 10 ° C. or more and 50 ° C. or less and a relative humidity of 70% or more.   The alkali metal-containing amorphous silica particles include alkali metal-containing amorphous silica particles having an alkali metal content, which is an alkali metal / Si molar ratio, of 0.40 or more and 0.85 or less. The manufacturing method in any one of.   The alkali metal-containing amorphous silica particles include a first alkali metal-containing amorphous silica particle having a first alkali metal content, and a second alkali metal content that is less than the first alkali metal content. The manufacturing method in any one of Claims 10-14 containing these 2nd alkali metal containing amorphous silica particles. A solid oxide fuel cell,
A battery provided with the sealing site | part by the sealing material in any one of Claims 1-9.   The solid oxide fuel cell according to claim 16, wherein the sealing material seals a polycrystalline substrate of the solid oxide fuel cell.