KR20130104858A - Fabrication of beta-alumina solid electrolyte with addition of beta-alumina seeds in spray-drying process and the secondary battery using it - Google Patents

Abstract

PURPOSE: A production method of beta-alumina solid electrolyte is provided to obtain a Na+-beta-alumina sintered body close to the theoretical density by calcinating and sintering after adding beta-alumina seeds. CONSTITUTION: A production method of beta-alumina solid electrolyte comprises the following steps: producing slurry using alpha-alumina, Na2CO3, and Mg(OH)2 as materials by ball-milling (S102); adding a binder, a dispersant, and an anti-foamer into the slurry; adding beta-alumina seeds into the slurry; spray drying the slurry containing the seeds to obtain alumina granules (S103); uniaxial pressing the alumina granules into disks (S104); compressing the molded disks using a hydrostatic pressure pressing process, and one-step calcinating and sintering the product (S106).

Description

FIELD OF THE INVENTION A method for preparing a beta alumina solid electrolyte by adding beta alumina seed in a spray drying process and a secondary battery comprising the composition. {Fabrication of beta-alumina solid electrolyte with addition of beta-alumina seeds in spray-drying process and the secondary battery using it

The present invention is to add beta-alumina in the spray drying process, and to use it as a seed (seed), more specifically, α-alumina and Na ₂ CO ₃ and Mg (OH) ₂ as a raw material Slurry production using a ball milling process, addition of binders, dispersants and anti-foamers for the stability of the slurry and the granules in the slurry process, In addition, beta-alumina as a seed (seed) process, and spray-drying (spray drying) to prepare alumina granules, it is formed into a disc (disc) form through a uniaxial press, hydrostatic pressure molding Pressing the green body by using a (CIP) process, the solid electrolyte to produce a Na ⁺ -beta-alumina sintered body by one-step calcination & sintering in one step solid electrolyte) and its synthesis It relates to a method and a secondary battery consisting of the composition.

Recently, a large-capacity power storage system is emerging as a part of the distributed power supply of smart grid system and new renewable energy. Currently, NAS battery is the only large-capacity (MW-class) power storage system proved to be stable and reliable and commercialized.

Currently, many studies have been conducted overseas, and NAS batteries using Na + -beta-alumina as a solid electrolyte have been used in Japan and China, but related studies are insufficient in Korea.

First, the NAS battery is a high-temperature battery operating at 290-360 ° C, so it is not affected by the surrounding environment. Also, it is suitable for wind power and solar power generation system without damage due to irregular charge-discharge.

And the charge-discharge efficiency (87%), and has a long lifetime of 15 years in normal operation. It also features No self-discharge and No maintenance.

Meanwhile, polycrystalline β "-alumina generally exhibits high density, low porosity, excellent strength, and low resistance, so that solid electrolyte and separator of NAS (Sodium Sulfur) battery, a secondary battery for power storage, are used. Suitable for use as a separator.

In addition, Korean Patent No. 1067447 discloses H ₃ O ⁺ / NH ₄ ⁺ -β ″ -alumina, which is a super ionic conductor, and CsHSO ₄ (Cesium hydrogen sulfate) and CsH _{2, which are} conductive solid acids. Infiltrated with PO ₄ (Cesium dihydrogen sulfate), made with CsHSO ₄ / H ₃ O ⁺ (NH ₄ ⁺ ) -β ″ -alumina, CsH ₂ PO ₄ / H ₃ O ⁺ (NH ₄ ⁺ ) -β ″ -alumina Will be.

In addition, Korean Patent No. 1067448 discloses H ₃ O ⁺ / NH ₄ ⁺ -β ″, a super ionic conductor ion-exchanged with acetic acid and ammonium nitrate using sintered K ⁺ -β "-alumina as a precursor. The superalumina hybrid membrane is prepared by infiltrating zirconium phosphate, a conductive solid acid, with -alumina as a support.

Therefore, there is a need for a technique capable of synthesizing an excellent beta-alumina solid electrolyte, which is suitable for use as a solid electrolyte, and in a simplified process from an existing generalized process.

In order to solve the above problems, the present invention relates to a method for synthesizing a dense Na ⁺ -beta-alumina solid electrolyte by adding beta-alumina seed to a spray drying process and a secondary battery comprising the composition, and the present invention provides an initial raw material. Phosphorus α-alumina, Na ₂ CO ₃ and Mg (OH) ₂ were mixed and slurry prepared by ball milling process to produce granules using spray drying, and then molded and pressurized by uniaxial pressure and hydrostatic pressure molding process. and in that to conduct the calcination and sintering process, in particular close to the beta-alumina to the theoretical density by the addition of beta-alumina as a seed in the granule production process for an important element in improving the mechanical properties for the use as a solid electrolyte Na ⁺ -beta Secondary charging of Na + -beta-alumina solid electrolyte composition through Na + -beta-alumina seed addition in spray drying process to obtain sintered alumina The purpose is to provide a paper and a method thereof.

In another aspect, the present invention is to prepare a slurry by mixing a small amount of additives and beta-alumina seeds of α-alumina and Na ₂ CO ₃ and Mg (OH) ₂ as an initial raw material by a ball milling process, and to prepare the slurry Preparing granules of initial raw material by spray drying process, forming granules into disc form by uniaxial pressure and hydrostatic pressurization, and obtaining dense Na ⁺ -beta-alumina sintered body by calcination & sintering process in one step It is an object of the present invention to provide a secondary battery and a method of the Na + -beta-alumina solid electrolyte composition through Na + -beta-alumina seed addition in a spray drying process.

The present invention is a process for producing a slurry (slurry) by a ball milling (ball milling) process using α-alumina, Na ₂ CO _3, and Mg (OH) ₂ as a raw material, and for the stability of the slurry in the slurry manufacturing process Adding a binder, a dispersant, and an anti-foamer, adding beta-alumina as a seed to the slurry, and spray drying after the seed addition process. To produce alumina granules, to form the alumina granules into a disc form through a uniaxial press, and to produce alumina granules by using a hydrostatic pressure molding (CIP) process. It pressurizes a green body, and consists of a process of calcination and sintering in one step.

The binder is PVA, the dispersant is ammonium polymethacrylate, the antifoam is Octanol, and 0.4 wt% to 0.6 wt% of the total powder is added as an additive.

In the spray drying process, the spray dryer inlet temperature setting of the drying process is 190 ~ 210 ^° C, outlet temperature setting is 100 ~ 120 ^° C to instantaneously prepare granules of raw materials by evaporation of the input slurry solvent and binder. Thus, granules of initial raw material powder having an average of 50 to 80 µm in size distribution are obtained.

In the uniaxial pressurization process, the raw material granules are pressurized to 40-50 Mpa to produce a disc-shaped molded body, and vacuum packed to carry out hydrostatic pressure molding, wherein the pressurized pressure is 150 to 250 Mpa. to be.

In the one-step calcination and sintering step, the molded body is calcined and sintered in one step in an air atmosphere, and the sintering temperature is maintained at 1500 to 1700 ^° C. for 20 to 40 minutes.

The present invention is a ball milling unit for preparing a slurry by receiving α-alumina, Na ₂ CO _3, and Mg (OH) ₂ as a raw material, a binder for the stability of the slurry in the slurry delivered from the ball milling unit, A dispersing agent and an antifoaming agent are added, and an addition part for adding beta-alumina as a seed to the slurry, a spray drying part for producing alumina granules received from the addition part, and the alumina granules in a disk form through uniaxial pressure. Pressurizing the uniaxial pressing unit for molding and the green body produced in the uniaxial pressing unit using a hydrostatic pressure molding (CIP) process, calcination and sintering (one-step calcination & sintering) in one step It consists of a sintered part.

In the addition part, the binder is PVA, the dispersant is ammonium polymethacrylate, the antifoam is Octanol, and 0.4 wt% to 0.6 wt% of the total powder is added as an additive. The spray drying unit has an inlet temperature setting of 190 ~ 210 ^o C, the outlet temperature is set to 100 ~ 120 ^° C to instantaneously prepare the granules of the raw materials by evaporation of the input slurry solvent and the binder, to obtain granules of the initial raw powder of the average 50 ~ 80 ㎛ size distribution .

The uniaxial pressurizing unit applies a pressure of 40-50 Mpa to the raw material granules to produce a disc-shaped molded body, and vacuum packs it to carry out hydrostatic pressure molding, wherein the pressurization pressure is 150 to 250 Mpa.

The calcining and sintering unit calcines and sinters the molded body in one step in an air atmosphere, and the sintering temperature is maintained at 1500 to 1700 ^° C. for 20 to 40 minutes.

After the slurry is prepared through the initial raw material powder by the process of the present invention, it is possible to obtain a variety of shaped bodies by obtaining the spray-dried granules, and to obtain beta-alumina sintered body close to the theoretical density through a calcination & sintering process in one step You can see the effect.

The sintered body according to the present invention may exhibit suitable mechanical properties for use in NAS cells, and the seed addition process is useful for use as a conductive solid electrolyte tube.

In addition, the beta-alumina seed addition process according to the present invention generally has the advantage of helping to create a uniform microstructure for the beta-alumina grain size distribution, and exhibits the effect of controlling the isolated and elongated grains.

Figure 1 shows the overall process sequence of the present invention. Figure 2 shows the change in density and β "-phase of Na ⁺ -beta-alumina sintered body with beta-alumina seed addition.

In general, the physical properties of ceramics are greatly influenced by various manufacturing processes, and thus the development of process technology has great significance in terms of practical use, and in the present invention, it is not a granule manufacturing through spray drying of beta-alumina powder, which is widely known. In order to simplify the process, the preparation of granules by spray drying method and the addition of a small amount of additives and beta-alumina seeds to the slurry composed of α-alumina, Na ₂ CO ₃ and Mg (OH) ₂ as the initial raw materials, and pressurization process The process of sintering and sintering a green body, which sinters and sinters it in one step, further simplifies the existing process. it is meant to to relieve the symptoms, the adjacent beta-alumina sintered body on Na ⁺ -beta-alumina solid electrolyte secondary battery as the theoretical density It will be described in detail below for properties and the manufacturing process and apparatus.

According to one embodiment of the present invention, a secondary battery made of a Na + -beta-alumina solid electrolyte composition through Na + -beta-alumina seed addition in a spray drying process includes a ball mill, an addition part, a spray drying part, and a uniaxial pressure. It is composed of a part, calcination and sintering part, but is not limited to this, but divided by the apparatus for treating each process according to the present invention and the place for processing the additive material is not limited thereto, and may include a specific configuration, if necessary, New configurations may be added further.

The ball mill is a device for preparing a slurry by receiving the α-alumina, Na ₂ CO _3, and Mg (OH) ₂ as a raw material, the beta-alumina preparation process for use as a seed (seed) undertake.

The addition unit is a device for adding a binder, a dispersant, and an antifoaming agent for the stability of the slurry to the slurry delivered from the ball mill, and add beta-alumina as a seed to the slurry.

In addition, it is preferable to use PVA as the binder added in the addition part, the dispersant as ammonium polymethacrylate, and the antifoaming agent as Octanol.

In this case, it is preferable to add 0.4 wt% to 0.6 wt% of each additive with respect to 100 wt% of the total raw material powder.

The spray drying unit is a device for producing alumina granules received from the addition unit,

The uniaxial pressurizing unit is a device for molding the alumina granules into a disk form through uniaxial pressurization.

In addition, the uniaxial pressure unit is a device for applying a pressure of 40 ~ 50 Mpa (more precisely about 48Mpa) of the raw material granules to produce a disk (disc) type molded body, vacuum packaging it to perform hydrostatic pressure molding. In this case, the pressurized pressure is preferably 150 to 250 Mpa (more precisely about 200 Mpa), and particularly, the spray drying unit has an inlet temperature setting of 190 to 210 ° C (more precisely about 200 ° C) and an outlet temperature setting of 100 to An apparatus for obtaining granules of initial raw material powders having an average of 50 to 80 µm in size distribution is prepared by instantaneous evaporation of the input slurry solvent and granulation of raw materials by a binder at 120 ° C (more precisely about 110 ° C).

The calcining and sintering unit is a device that pressurizes the green body generated in the uniaxial pressurization unit by using a hydrostatic pressure molding (CIP) process, and one-step calcination & sintering in one step.

In addition, the calcining and sintering unit calcines and sinters the molded body in one step in an air atmosphere, and the sintering temperature is maintained at 1500 to 1700 ° C (more precisely about 1650 ° C) for 20 to 40 minutes (or about 30 minutes). .

In one embodiment of the present invention, for the synthesis and preparation of polycrystalline β "-alumina sintered body having high density and sufficient strength, beta-alumina synthesis and preparation for use as a seed (calcination: 1200 ^o C 2hr), ball In the slurry manufacturing process through milling, the beta-alumina is added as a seed at a ratio of 3 to 10 wt% of the raw powder, followed by preparation of granules through a spray drying process, and molding of seeded granules and unseeded granules through spray drying. After the one-step calcination & sintering process, the relative density and β "-phase change were confirmed by adding beta-alumina seed, and thus the Na ⁺ -beta-alumina sintered body was added to beta-alumina seed. It was.

Hereinafter, the entire process for carrying out the present invention may be represented by FIG. 1, which will be described in detail with reference to this.

1) Production of slurry for mixing each raw material and spray drying through ball milling (S101, S102) In the process of the present invention, for the synthesis of beta-alumina, the initial raw material is α-alumina, Na ₂ CO ₃ and Mg (OH) ₂ was used, and the solvent was DI water for mixing and slurrying each raw material in the ball milling process and spray drying process. In order to facilitate the stability of the slurry and the preparation of granules, a binder was used. PVA as, ammonium polymethacrylate as a dispersant and Octanol as an antifoam were added to the slurry, and 0.4 wt% to 0.6 wt% of the raw powder were added as additives, respectively. In this process, in order to confirm the influence of beta-alumina seeds, a series of processes using slurry without adding seeds and a series of slurries using beta-alumina seeds added with 3 to 10 wt% to the raw material powder are used. The experiment proceeded to the process.

2) spray drying (S103)

In the present invention, spray drying was performed to prepare granules of the raw material powder. In this process, the spray dryer inlet temperature is set to 200 ^o C and the outlet temperature is set to 110 ^o C. Granules of materials were prepared, and granules of initial raw powder with an average 50-80 μm size distribution were obtained.

3) Uniaxial press and Cold isotactic press (S104, S05)

In this step, as a step of forming the granules of the initial raw material, the raw material granules were applied to the pressure of 48 Mpa to prepare a disc-shaped molded body, and vacuum packing was carried out to carry out hydrostatic pressure molding. The pressure was 200 Mpa, which was carried out for the formation of sufficient strength for the handling of the molded body, and the purpose was to help the densification in the sintering process.

4) one-step calcination & sintering (S106, S107)

In this step, the prepared molded body was calcined and sintered in one step in an air atmosphere, and a sintering program was used to maintain the sintering temperature at 1650 ^o C for 30 minutes. -alumina was obtained, and densification of the crystals was induced by applying a temperature above the eutectic point, thereby obtaining a sintered body having sufficient strength as a beta-alumina solid electrolyte.

Analysis and consideration of test results (one-step calcination and sintering results analysis of molded product)

The results of the present invention through molding and one-step calcination & sintering using unseeded and seeded granules are shown in FIG. The present invention was able to obtain a ceramic sintered body (sintered body) having a relative density of up to 96% of the theoretical beta-alumina density by using a seed addition process.

This sintered compact, which can be used as a solid electrolyte for NAS secondary batteries, showed that the β "-alumina phase fraction, which has a dominant role in ion conductivity, decreased slightly as the beta-alumina seed content increased. The present invention was able to obtain a sintered body close to the theoretical density through the molding and sintering process after the granulation of the initial raw material powder, which solves the problem of the existing density by adding a small amount of beta-alumina seed in the granulation process It was.

Beta-alumina β "-phase analysis in the present invention was carried out as follows, shown in Figure 2.

If the measured peak is on the α-alumina were analyzed JCPDS Card 10-173, β ^'' -alumina phase 31-1263, β ^'' of data -alumina phase 31-1262 by reference.

The phase fraction has been used on the assumption that the integral intensity of other phases in addition to the β ″ alumina phase is proportional to the fraction of each phase. In the present invention, three phases in the composite have three phases, namely a-, β-, and β ″ alumina. Considering the case where only phase exists, the relative fraction was calculated by Equation 1 below.

[Equation 1]

The detailed peak calculation at each phase is shown in Equation 2 below.

&Quot; (2) "

I _{α (104) (113)} : X-ray intensity of the (104) and (113) planes of a-alumina

_{I0 (012) (026) (017)} : X-ray intensity of the (012), (017), and (026) plane of β-alumina

I _{β "1011) (2010)} : X-ray intensity of (10 11 ), (20 10 ) plane of β" alumina

(012), (017), (026) crystal planes (JCPDS file 31-1263) of? -Alumina, (104) and The peaks of (10 11 ) and (20 10 ) crystal planes of β "alumina (JCPDS file 31-1262) were used.

Claims (10)

preparing a slurry by a ball milling process using α-alumina, Na ₂ CO _3, and Mg (OH) ₂ as raw materials;
Adding a binder, a dispersant, and an anti-foamer for stability of the slurry in the slurry manufacturing process;
Adding beta-alumina as a seed to the slurry;
Spray drying after the seed addition process to produce alumina granules;
Molding the alumina granules into a disc form through a uniaxial press;
Pressurizing the green body produced in the molding process using a hydrostatic pressure molding (CIP) process, and one-step calcination & sintering in one step;
Method for producing a Na + -beta-alumina solid electrolyte through the addition of Na + -beta-alumina seed in the spray drying process, characterized in that consisting of. The method of claim 1,
The binder is PVA, the dispersant is ammonium polymethacrylate, the antifoam is Octanol,
A method for producing a Na + -beta-alumina solid electrolyte by adding Na + -beta-alumina seeds in a spray drying process, wherein 0.4 wt% to 0.6 wt% are added as additives to 100 wt% of the total raw material powder. According to claim 1, In the spray drying step, the spray dryer inlet temperature setting of the drying step is 190 ~ 210 ^o C, outlet temperature setting is 100 ~ 120 ^o C instantaneously added by evaporation of the slurry solvent and the binder A method for producing a Na + -beta-alumina solid electrolyte by adding Na + -beta-alumina seed in a spray drying process, wherein granules of raw materials are prepared to obtain granules of initial raw powder having an average size of 50 to 80 μm. According to claim 1, The uniaxial pressure process, the raw material granules by applying a pressure of 40 to 50 Mpa to produce a disk (disc) type molded body, and vacuum-packed it to carry out hydrostatic pressure molding, the pressurization at this time The pressure is 150 ~ 250 Mpa Na + -beta-alumina solid electrolyte manufacturing method through the addition of Na + -beta-alumina seed in the spray drying process, characterized in that. The method of claim 1,
The one-step calcination and sintering process,
The molded body is calcined and sintered in one step in an air atmosphere, and the sintering temperature is maintained at 1500 to 1700 ^o C for 20 to 40 minutes in the spray drying process, wherein Na +-through Na + -beta-alumina seed addition is performed. Method for preparing beta-alumina solid electrolyte. a ball mill unit for preparing a slurry by inputting α-alumina, Na ₂ CO _3, and Mg (OH) ₂ as a raw material;
An addition part for adding a binder, a dispersant, and an antifoaming agent for stability of the slurry to the slurry transferred from the ball mill, and adding beta-alumina as a seed to the slurry;
Spray drying unit for producing alumina granules received from the addition unit;
A uniaxial pressurizing unit for molding the alumina granules into a disk form through uniaxial pressurization;
A calcining and sintering unit for pressurizing the green body produced by the uniaxial pressurization unit using a hydrostatic pressure molding (CIP) process, and one-step calcination & sintering in one step;
Secondary battery consisting of Na + -beta-alumina solid electrolyte composition through the addition of Na + -beta-alumina seed in the spray drying process, characterized in that consisting of. The method according to claim 6,
In the addition portion,
The binder is PVA, the dispersant is ammonium polymethacrylate, the antifoam is Octanol,
A secondary battery comprising a Na + -beta-alumina solid electrolyte composition through the addition of Na + -beta-alumina seed in a spray drying process, characterized in that 0.4 wt% to 0.6 wt% are added as additives with respect to 100 wt% of the raw material powder. According to claim 6, The spray drying unit,
Instant inlet temperature of 190-210 ^o C and outlet temperature of 100-120 ^o C were instantaneously prepared with granules of raw materials by evaporation of the input slurry solvent and granules of the binder. A secondary battery made of a Na + -beta-alumina solid electrolyte composition through the addition of Na + -beta-alumina seed in the spray drying process, characterized in that to obtain a granule of the powder. The method according to claim 6,
The uniaxial pressing unit,
Applying a pressure of 40 ~ 50 Mpa to the raw material granules to produce a disk (disc) type molded body, and vacuum packing it to carry out hydrostatic pressure molding, wherein the pressure is spraying, characterized in that 150 ~ 250 Mpa Secondary battery consisting of Na + -beta-alumina solid electrolyte composition through the addition of Na + -beta-alumina seed in the drying process. The method according to claim 6,
The calcining and sintering unit,
The molded body is calcined and sintered in one step in an air atmosphere, and the sintering temperature is maintained at 1500 to 1700 ^o C for 20 to 40 minutes in the spray drying process, wherein Na +-through Na + -beta-alumina seed addition is performed. Secondary battery consisting of a beta-alumina solid electrolyte composition.

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