Refractory saggar for calcining precursor materials

Abstract

The present specification relates to a refractory sagger for calcining a precursor material, and more particularly, to a refractory sagger for calcining a precursor material, the refractory sagger for calcining a precursor material comprising a body having a space for loading a precursor material, the present invention relates to a main body which can suppress the generation of by-products during the calcination of the precursor material contained in the inner space of the main body and improve the durability of the main body, thereby prolonging the service life thereof.

Description

Technical Field

[0001] The present invention is a refractory sagger for calcining precursor materials, and more specifically, relates to a refractory sagger for calcining precursor materials, the refractory sagger for calcining precursor materials comprising a main body having a space for loading the precursor material, and capable of suppressing the generation of by-products during the calcination of the precursor material loaded into the space within the main body, while improving the durability of the main body, thereby extending the service life. Background Art

[0002] Various inorganic compounds are prepared by heat treatment (calcination) of precursor materials.

[0003] Generally, calcination of a precursor material of an inorganic compound is achieved by charging the precursor material into a heat treatment container having heat resistance and chemical resistance (hereinafter referred to as a "refractory sagger") and performing a heat treatment at a predetermined temperature.

[0004] At this time, the precursor material of the compound to be heat-treated (inorganic compound or its raw material) is placed inside the refractory sagger, and thus calcined by heating without being directly exposed to flame, smoke, and the like.

[0005] Therefore, the refractory sagger must basically ensure stability at the calcination temperature of the precursor material, that is, predetermined heat resistance and chemical resistance.

[0006] A representative example of an inorganic compound prepared by heat treatment of a precursor material is a positive electrode active material for a lithium battery.

[0007] Compounds used as positive electrode active materials for lithium batteries include lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, or composite oxides thereof (eg, NCM, NCA-based lithium composite oxides), and the like.

[0008] In the case of the positive electrode active material, a transition metal-containing precursor material and a lithium-containing raw material (eg, LiOH) are loaded into a refractory sagger and then heat-treated at a temperature of 600° C. to 1,200° C. to prepare.

[0009] Therefore, the refractory sagger used to prepare the positive electrode active material is prepared using high heat-resistant ceramic materials such as cordierite, mullite, spinel, etc. as the main component to ensure sufficient heat resistance within the above-mentioned heat treatment temperature range.

[0010] On the other hand, in recent years, there has been concern about the problem of by-products being generated in the refractory sagger due to a side reaction between the lithium-containing raw material and the main component of the refractory sagger at the heat treatment temperature of the precursor material.

[0011] Specifically, lithium contained in lithium-containing raw materials such as LiOH and Li2CO3 added to the refractory sagger for calcination of precursor materials penetrates into the refractory sagger during the calcination process, and may react with Al2O3, SiO2, etc., which are main components of the refractory sagger.

[0012] By the infiltration and reaction of lithium as described above, Li x -(Al / Si) y -O z By-products of etc.

[0013] According to the above mechanism, as the calcination process using the above refractory sagger is repeated, the thickness of the by-product layer deposited on the above refractory sagger increases.

[0014] Since a byproduct layer is generated on the inner wall of the refractory sagger, the inner wall of the refractory sagger may be damaged, which may shorten the strength and life of the refractory sagger.

[0015] In addition, the by-product layer may cause a problem of being peeled off during calcination and mixed into the positive electrode active material.

[0016] To improve this, technologies have been introduced to reduce the possibility of by-product generation by excluding silicon-containing raw materials from the main components of the refractory sagger, or to reduce the side reaction between the refractory sagger and the lithium-containing raw material by coating the inner wall of the refractory sagger with spinel or the like.

[0017] However, when the silicon-containing raw material in the main component of the refractory sagger is reduced, the content of the aluminum-containing raw material must be increased. In this case, there is a problem that the possibility of generating by-products derived from aluminum instead of by-products derived from silicon increases, and there is also a problem that the overall strength of the refractory sagger decreases due to the exclusion or reduction of the silicon-containing raw material in the main component of the refractory sagger.

[0018] Prior art literature

[0019] Patent Literature

[0020] (Patent Document 1) Korean Patent Publication No. 10-2020-0058383 (Publication Date: 2020.05.27)

[0021] (Patent Document 2) Korean Patent Gazette No. 10-1161139 (Published on July 2, 2012)

[0022] (Patent Document 3) Korean Patent Publication No. 10-1448417 (Publication Date: 2014.10.07) Summary of the invention

[0023] Technical issues

[0024] An object of the present specification is to provide a refractory sagger having sufficient heat resistance under the temperature conditions applied during the calcination of a precursor of an inorganic compound.

[0025] In addition, another object of the present specification is to provide a refractory sagger, which, unlike the existing refractory sagger, can prevent the generation of lithium-containing raw materials such as Li by reducing the side reaction between the lithium-containing raw materials loaded into the refractory sagger and the main components of the refractory sagger. x -(Al / Si) y -O z By-products of etc.

[0026] In addition, another object of the present specification is to provide a refractory sagger having sufficient strength to effectively withstand the pressure or high temperature calcination conditions applied to the inner wall of the refractory sagger when the precursor material is loaded into the sagger and then pressed.

[0027] The purpose of this specification is not limited to the purpose mentioned above, and other purposes and advantages of this specification that are not mentioned can be understood through the following description, and can be more clearly understood through the embodiments of this specification. In addition, it can be easily understood that the purpose and advantages of this specification can be achieved by the means and combinations thereof in the claims.

[0028] Solutions to the problem

[0029] According to one aspect of the present specification, there is provided a refractory sagger for calcining a precursor material, which is a refractory sagger including a main body having a space for loading the precursor material, the main body including a first metal oxide as a main material, and a protective layer including a second metal oxide that does not contain lithium is formed on at least a portion of the inner surface of the main body constituting the space.

[0030] In one embodiment, the first metal oxide may include at least one selected from spinel, corundum, mullite, cordierite, spodumene, zircon, quartz, petalite, eucryptite, lithium disilicate, lithium metasilicate, forsterite, magnesium metasilicate, alumina and silicate.

[0031] In another example, the second metal oxide may react with lithium to form a lithium composite oxide capable of inserting / deinserting lithium.

[0032] At this time, the lithium composite oxide may be represented by the following Chemical Formula 1.

[0033] [Chemical formula 1]

[0034] Li w1 M x1 O 2-y1 X y1

[0035] (wherein, M is at least one selected from Al, Au, B, Ba, Ca, Ce, Co, Cr, Cu, Eu, F, Fe, Ga, Gd, Ge, Hf, K, Mg, Mn, Mo, Na, Nb, Nd, Ni, P, Pt, Si, Sm, Sn, Sr, Ta, Ti, V, W, Y, Zn and Zr, X is at least one selected from F, P and S, 0.5≤w1≤1.5, 0≤x1≤1, 0≤y1≤2)

[0036] On the other hand, the difference in thermal expansion coefficient between the main body and the protective layer may be 5×10 -6 / ℃ below.

[0037] In one embodiment, the second metal oxide may be represented by the following Chemical Formula 2.

[0038] [Chemical formula 2]

[0039] M 1 x2 M 2 y2 O 2-z2 X z2

[0040] (Among them, M 1 is at least one selected from Ni, Co, Mn and Al, M 2 is at least one selected from Au, B, Ba, Ca, Ce, Cr, Cu, Eu, F, Fe, Ga, Gd, Ge, Hf, K, Mg, Mo, Na, Nb, Nd, P, Pt, Si, Sm, Sn, Sr, Ta, Ti, V, W, Y, Zn and Zr, X is at least one selected from F, P and S, 0 <x2≤1,0≤y2≤1,0≤z2≤2)

[0041] In addition, the content of the second metal oxide in the protective layer may be 95 wt % or less.

[0042] The difference in thermal expansion coefficient between the main body and the protective layer may be 5×10 -6 / ℃ below.

[0043] On the other hand, the porosity of the protective layer may be 20 volume % or less.

[0044] In one embodiment, the refractory sagger for calcining a precursor material may further include an adhesive layer, wherein the adhesive layer is located between the protective layer and the main body and includes the first metal oxide and the second metal oxide.

[0045] At this time, in the adhesive layer, the second metal oxide may be included in an amount of 10 parts by weight to 200 parts by weight based on 100 parts by weight of the first metal oxide.

[0046] In another embodiment, at least a portion of the protective layer may further include a third metal oxide that does not contain lithium.

[0047] Among them, the above-mentioned third metal oxide may include at least one selected from (1) at least one oxide containing a metal element selected from 1A (excluding lithium), 2A, 4B, 8B, 3A and 4A; and (2) at least one composite oxide containing multiple oxides of a metal element selected from 1A (excluding lithium), 2A, 4B, 8B, 3A and 4A.

[0048] On the other hand, in the protective layer, the weight ratio of the second metal oxide to the third metal oxide may be 35-65:65-35, respectively.

[0049] According to another aspect of the present specification, there is provided a method for preparing a refractory sagger for calcining a precursor material, comprising: step (a), preparing a molded body, wherein the molded body comprises a first metal oxide as a main material and is molded into a predetermined shape to include a space for loading the precursor material, and at least a portion of the surface of the molded body contains a protective composition comprising a second metal oxide that does not contain lithium; and step (b), heat treating the molded body at 500°C to 1,400°C.

[0050] In one embodiment, in the step (a), a bonding composition including a first metal oxide and a second metal oxide not containing lithium may be further included between the main body of the molded body and the protective composition.

[0051] In addition, the protective composition may further include a third metal oxide that does not contain lithium.

[0052] Effects of the Invention

[0053] According to the present description, by forming a protective layer on at least a portion of the refractory sagger or improving the peeling resistance of the main body, the side reaction between the charged lithium-containing raw material and the main body can be reduced compared with the conventional refractory sagger.

[0054] Therefore, the generation of by-products such as Li—(Al / Si)—O is reduced, thereby improving the durability of the refractory sagger, and further preventing the contamination of the calcined product due to the by-products.

[0055] In addition to the above-described effects, specific effects of the present specification will be described while explaining specific details of the present specification. DETAILED DESCRIPTION

[0056] Specific terms are defined herein to facilitate understanding of this specification. Unless specifically defined herein, scientific terms and technical terms used herein should have the meanings commonly understood by those skilled in the art. In addition, it should be understood that, unless the context clearly indicates otherwise, singular forms are intended to include plural forms, and vice versa.

[0057] Hereinafter, a refractory sagger for calcining a precursor material according to the present specification will be described in more detail.

[0058] Refractory sagger for calcining precursor materials

[0059] According to one aspect of the present specification, there is provided a refractory sagger for calcining a precursor material, which is a refractory sagger including a main body having a space for loading the precursor material, the main body including a first metal oxide as a main material, and a protective layer including a second metal oxide that does not contain lithium is formed on at least a portion of the inner surface of the main body constituting the space.

[0060] Here, including the first metal oxide as the main material means that more than 50 weight % of the components constituting the main body are the first metal oxide, or at least one of the weight ratio, molar ratio and volume ratio of the components belonging to the first metal oxide in various compositions is the highest.

[0061] A refractory sagger is a refractory container used to calcine precursor materials to produce desired products while preventing direct contact with flames, smoke, etc.

[0062] Therefore, the shape of the sagger is not limited to a prism, a cylinder, an elliptical cylinder, etc., and it can be used in various shapes according to the purpose as long as it includes a space inside which the precursor material can be placed.

[0063] Examples of the above-mentioned precursor material include lithium-based oxides and the like for preparing a positive electrode active material.

[0064] Generally, a precursor for preparing a positive electrode active material includes transition metals such as cobalt, nickel, manganese, iron, and aluminum, which are calcined with a lithium compound to form a lithium-based composite oxide, which can be used as a positive electrode active material.

[0065] However, in the above-mentioned calcination process, lithium penetrates into the refractory sagger and reacts, and as a result, there may occur a problem that the constituent components of the refractory sagger deteriorate and peel off.

[0066] In order to minimize the manufacturing cost of the final product after calcination, the refractory sagger must be reused, but the refractory sagger that has been delaminated may reduce the product performance and thus cannot or is difficult to reuse.

[0067] According to an aspect of the present specification, such deterioration and peeling problems can be improved by forming a protective layer on at least a portion of the inner surface of the space inside the refractory sagger in which the precursor material is loaded.

[0068] That is, the refractory sagger may have a double-layer structure, a three-layer structure, or a structure composed of layers above the double-layer structure, at least a portion of which includes a main body and a protective layer.

[0069] As an example of such a refractory sagger, a protective layer may be formed on the bottom surface of the inner space of the refractory sagger into which lithium is more easily permeated due to gravity, but the present invention is not limited thereto.

[0070] Since the sagger must be repeatedly subjected to a high-temperature calcination process, it may be made of a ceramic material having a high melting point.

[0071] Ceramic materials are materials composed of compounds formed by combining metal elements such as silicon (Si), aluminum (Al), titanium (Ti), zirconium (Zr), and magnesium (Mg) with non-metal or metalloid elements such as oxygen, carbon, and nitrogen through high-temperature heat treatment.

[0072] For example, the ceramic material constituting the refractory sagger for calcining the precursor material of the present application may include Al2O3, MgO, SiO2, K2O, ZrO, ZrO2, CaO and Fe x O y The various materials known as the materials constituting the refractory sagger are as follows.

[0073] In addition to the chemical composition represented by the above formula, the properties of ceramic materials may also vary depending on the morphology, ie, the type of mineral phase, in which they are formed.

[0074] Examples of mineral phases of ceramic materials that can be used for refractory saggers in the present specification include spinel, corundum, mullite, cordierite, spodumene, zircon, quartz, petalite, eucryptite, lithium disilicate, lithium metasilicate, forsterite, magnesium metasilicate, alumina, silicate, and the like.

[0075] That is, the first metal oxide may include at least one selected from spinel, corundum, mullite, cordierite, spodumene, zircon, quartz, petalite, eucryptite, lithium disilicate, lithium metasilicate, forsterite, magnesium metasilicate, alumina and silicate, but the present invention is not limited thereto.

[0076] In a non-limiting example, the first metal oxide may include spinel, corundum, mullite, cordierite, and optionally zircon. In the above example, the content range of at least one of 30 wt % to 50 wt % of spinel, 1 wt % to 15 wt % of corundum, 1 wt % to 25 wt % of mullite, 25 wt % to 50 wt % of cordierite, and 0 wt % to 5 wt % of zircon may be included, respectively, but the present invention is not limited thereto.

[0077] For example, the spinel content can be 30 weight %, 31 weight %, 32 weight %, 33 weight %, 34 weight %, 35 weight %, 36 weight %, 37 weight %, 38 weight %, 39 weight %, 40 weight %, 41 weight %, 42 weight %, 43 weight %, 44 weight %, 45 weight %, 46 weight %, 47 weight %, 48 weight %, 49 weight %, 50 weight % or a range between two values.

[0078] On the other hand, the content of corundum can be 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, or a range therebetween.

[0079] The content of mullite can be 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt% or a range between two values.

[0080] Furthermore, the cordierite content can be 25 weight%, 26 weight%, 27 weight%, 28 weight%, 29 weight%, 30 weight%, 31 weight%, 32 weight%, 33 weight%, 34 weight%, 35 weight%, 36 weight%, 37 weight%, 38 weight%, 39 weight%, 40 weight%, 41 weight%, 42 weight%, 43 weight%, 44 weight%, 45 weight%, 46 weight%, 47 weight%, 48 weight%, 49 weight%, 50 weight% or a range between two values.

[0081] The optional zircon may be present in an amount of 0 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, or a range therebetween.

[0082] The content of at least one of the components of the first metal oxide may fall within the above range.

[0083] The general form of these materials is described below, but is not limited thereto. For example, the coefficient of thermal expansion of each component is an example value measured within a temperature range of 25°C to 800°C.

[0084] Spinel is an isometric mineral represented by MgO·Al2O3, for example, it can have a -6 / ℃ thermal expansion coefficient.

[0085] Corundum is a hexagonal mineral represented by Al2O3, for example, can have a -6 / ℃ thermal expansion coefficient.

[0086] Mullite is a tetrahexagonal mineral represented by 3Al2O3·2SiO2, and can have a crystal structure of 5.84×10 -6 / ℃ thermal expansion coefficient.

[0087] Cordierite is a tetrahexagonal mineral represented by 2MgO·2Al2O3·5SiO2, and may have a crystal structure of 1.76×10 -6 / ℃ thermal expansion coefficient.

[0088] Spodumene is represented by Li2O·Al2O3·nSiO2 and is divided into monoclinic α-spodumene and tetragonal β-spodumene according to the production temperature. For example, it can have a 0.44×10 -6 / ℃ thermal expansion coefficient.

[0089] Zircon is a hexagonal mineral represented by ZrO2·SiO2, and can have a -6 / ℃ thermal expansion coefficient.

[0090] Quartz is a hexagonal mineral represented by SiO2, which can have a crystal structure of 7.64×10 -6 / ℃ thermal expansion coefficient.

[0091] These minerals react with lithium to degrade into phases of Li4SiO4, β-LiAlO2, γ-LiAlO2, MgO, etc.

[0092] These deteriorated phases will reduce the bonding strength between the components and become the cause of the refractory sagger peeling.

[0093] Specifically, when the precursor material is calcined using the refractory sagger, lithium from the lithium-containing raw material (LiOH, etc.) contained in the precursor material penetrates into the refractory sagger, so that the lithium x -(Al / Si) y -O z Impurities represented by the composition of the above-mentioned refractory sagger are deposited on the inner side.

[0094] With repeated use of the refractory sagger, an impurity layer (or referred to as a deteriorated layer) having a predetermined thickness may be generated on the inner side, especially the bottom surface, of the refractory sagger.

[0095] If cracks appear in the impurity layer generated as described above or the impurity layer peels off from the refractory sagger, not only is there a risk that the quality of firing using the refractory sagger will be drastically reduced, but there is also a possibility that the refractory sagger cannot be used.

[0096] In order to improve the above problem, a protective layer is formed in the inner space of the refractory sagger into which the precursor material is placed to inhibit the lithium in the lithium-containing raw material (LiOH, etc.) contained in the precursor material from penetrating into the refractory sagger to form impurities, thereby improving the life characteristics of the refractory sagger.

[0097] A protective layer containing a lithium composite oxide is formed in the internal space of the refractory sagger, which can prevent peeling due to the penetration of lithium. Even if part of the protective layer is peeled off and mixed into the calcined product, the degradation of product performance can be minimized, thereby extending the life characteristics of the refractory sagger.

[0098] Among them, lithium composite oxides can realize the insertion and extraction of lithium ions.

[0099] For example, the above-mentioned lithium composite oxide can be lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium iron phosphate compound (LFP), lithium nickel cobalt manganese oxide (NCM) and lithium nickel cobalt aluminum oxide (NCA), or compounds thereof doped and / or coated with specific elements, but the present invention is not limited thereto.

[0100] When the protective layer containing the lithium composite oxide is formed on the inner surface of the refractory sagger, it is possible to suppress the occurrence of side reactions during the calcination of the charged lithium-containing raw material.

[0101] Therefore, the generation of by-products such as Li—(Al / Si)—O is reduced, thereby improving the durability of the sagger, and further preventing the degradation of product performance due to contamination of the calcined product.

[0102] However, if the refractory sagger contains a composite lithium oxide, the unit cost may increase relatively. In addition, the lithium in the lithium composite oxide contained in the protective layer may react with the raw material of the refractory sagger to generate cracks.

[0103] To prevent this, the protective layer may include a second metal oxide that does not contain lithium and reacts with lithium to form a lithium composite oxide that can intercalate / deintercalate lithium.

[0104] In another example, the lithium composite oxide formed by reacting lithium with the second metal oxide may be represented by the following Chemical Formula 1.

[0105] [Chemical formula 1]

[0106] Li w1 M x1 O 2-y1 X y1

[0107] (wherein, M is at least one selected from Al, Au, B, Ba, Ca, Ce, Co, Cr, Cu, Eu, F, Fe, Ga, Gd, Ge, Hf, K, Mg, Mn, Mo, Na, Nb, Nd, Ni, P, Pt, Si, Sm, Sn, Sr, Ta, Ti, V, W, Y, Zn and Zr, X is at least one selected from F, P and S, 0.5≤w1≤1.5, 0≤x1≤1, 0≤y1≤2)

[0108] Among them, the above-mentioned w1 can be 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5 or a range between two values.

[0109] On the other hand, the above-mentioned x1 can be 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1 or a range between two values.

[0110] The above-mentioned y1 can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2 or a range between two values.

[0111] In other words, during the calcination process, the protective layer reacts with the lithium-containing raw material contained in the precursor to form a lithium composite oxide, thereby minimizing the increase in unit cost and suppressing peeling due to lithium penetration, or, even if a portion is peeled off and mixed into the calcined product, the deterioration of product performance can be minimized.

[0112] In addition, in one example, the ratio of lithium composite oxide in the region of the protective layer close to the main body of the refractory box body is low, so the problem of cracks caused by the reaction between the raw material of the refractory box body and lithium can be improved.

[0113] As an example of the second metal oxide as described above, a compound represented by the following Chemical Formula 2 can be cited.

[0114] [Chemical formula 2]

[0115] M 1 x2 M 2 y2 O 2-z2 X z2

[0116] (Among them, M 1 is at least one selected from Ni, Co, Mn and Al, M 2 is at least one selected from Au, B, Ba, Ca, Ce, Cr, Cu, Eu, F, Fe, Ga, Gd, Ge, Hf, K, Mg, Mo, Na, Nb, Nd, P, Pt, Si, Sm, Sn, Sr, Ta, Ti, V, W, Y, Zn and Zr, X is at least one selected from F, P and S, 0 <x2≤1,0≤y2≤1,0≤z2≤2)

[0117] Among them, the above-mentioned x2 can be 0.001, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1 or a range between two values.

[0118] On the other hand, the above-mentioned y2 can be 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1 or a range between two values.

[0119] Furthermore, the above-mentioned z2 can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2 or a range between two values.

[0120] For example, the second metal oxide may be nickel oxide, manganese oxide, cobalt oxide or a mixture thereof, but the present invention is not limited thereto.

[0121] Manganese oxide, which is an example of various second metal oxides not containing lithium, can form a lithium composite oxide through the following reaction formula during the calcination of a lithium-containing precursor material.

[0122] [Reaction formula]

[0123] 4LiOH+8MnO2→4LiMn2O4+2H2O+O2

[0124] In particular, the above-mentioned reaction may be more actively performed in the protective layer in a region in contact with the space where the precursor material is charged than in a region in contact with the refractory sagger body.

[0125] As a result, the phenomenon that lithium in the precursor material penetrates and causes peeling can be suppressed, and the life of the refractory sagger can be extended.

[0126] In another embodiment, the lithium composite oxide formed during the calcination of the precursor material in the protective layer may be a dense body, but the present invention is not limited thereto. As used herein, "dense body" may refer to a lithium composite oxide in a film-like form formed by fusion between particles.

[0127] If the lithium composite oxide formed in the refractory sagger protective layer is a dense body, the side reactions generated by the lithium-containing raw materials loaded into the refractory sagger during the calcination process can be more effectively suppressed. The lithium composite oxide as a dense body contains a small amount of pores or no pores, thereby reducing the penetration of lithium and / or the reactivity with LiOH.

[0128] On the other hand, for example, the content of the second metal oxide in the above-mentioned protective layer can be less than 95 weight %, for example, it can be 95 weight %, 90 weight %, 85 weight %, 80 weight %, 75 weight %, 70 weight %, 65 weight %, 60 weight %, 55 weight %, 50 weight %, 45 weight %, 40 weight %, 35 weight %, 30 weight %, 25 weight %, 20 weight %, 15 weight %, 10 weight %, 5 weight %, 1 weight % or a range between two values ​​therein, but the present invention is not limited thereto.

[0129] In addition to the second metal oxide not containing lithium, the protective layer may further include the ceramic material, for example, the first metal oxide, the third metal oxide not containing lithium, and the like.

[0130] In one embodiment, the difference in thermal expansion coefficient between the main body and the protective layer can be adjusted to 5×10 -6 / °C or less to prevent the main body from being separated from the protective layer during repeated calcination processes using the refractory sagger. However, the refractory sagger of the present specification is not limited thereto, and other means for minimizing separation between the main body and the protective layer may be applied.

[0131] Here, the thermal expansion coefficient may refer to the ratio of the volume change of each layer per 1° C. at a temperature for calcining the precursor material, for example, at 25° C. to 800° C. If the difference in thermal expansion coefficients between the main body and the protective layer is too large, the degree of expansion when the temperature rises may vary, resulting in reduced structural stability of the refractory sagger.

[0132] On the other hand, the porosity of the protective layer can be less than 20% by volume, for example, 20% by volume, 17.5% by volume, 15% by volume, 12.5% ​​by volume, 10% by volume, 7.5% by volume, 5% by volume, 2.5% by volume or less than 1% by volume. An exemplary method for achieving the above porosity is to densify the protective layer. If the porosity of the protective layer in direct contact with the lithium-containing raw material loaded into the refractory crucible is within the above range, the peeling phenomenon caused by the penetration of lithium and / or the reaction with LiOH can be further suppressed. However, the refractory crucible of the present specification is not limited thereto.

[0133] In another embodiment of the present specification, the refractory sagger may further include an adhesive layer, wherein the adhesive layer is located between the protective layer and the main body and includes the first metal oxide and a second metal oxide that does not contain lithium.

[0134] Regarding the first metal oxide and the second metal oxide, reference may be made to the above contents.

[0135] Depending on the composition and mineral phase of the protective layer, separation between the protective layer and the main body may easily occur. In this case, separation of the protective layer can be minimized by forming an adhesive layer between the protective layer and the main body having excellent adhesion to both layers.

[0136] Herein, compared with the protective layer, the ratio of the second metal oxide in the adhesive layer may be lower, and the ratio of the first metal oxide may be higher.

[0137] The more similar the composition of the bonding layer is to the composition of the adjacent region, the stronger the bonding force is. In addition, the components in the bonding layer can be formed to have a concentration gradient. For example, the ratio of the first metal oxide can be higher in the region close to the main body, and the ratio of the second metal oxide can be higher in the region close to the protective layer, but the present invention is not limited to this.

[0138] On the other hand, in the adhesive layer, based on 100 parts by weight of the first metal oxide, the content of the second metal oxide may be 10 parts by weight to 200 parts by weight, for example, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, 85 parts by weight, 90 parts by weight, 150 parts by weight, 155 parts by weight, 160 parts by weight, 165 parts by weight, 170 parts by weight, 175 parts by weight, 180 parts by weight, 185 parts by weight, 190 parts by weight, 195 parts by weight, 200 parts by weight, or a range between two values.

[0139] In another embodiment of the present specification, at least a portion of the protective layer may further include a third metal oxide that is different from the second metal oxide and does not contain lithium. As the third metal oxide that does not contain lithium, a metal oxide with low high temperature shrinkage, high thermal shock resistance or excellent corrosion resistance is used, thereby compensating for the weakness of the second metal oxide.

[0140] As an example, the third metal oxide may include at least one selected from (1) at least one oxide containing a metal element selected from 1A (excluding lithium), 2A, 4B, 8B, 3A and 4A; and (2) at least one composite oxide containing a plurality of oxides of a metal element selected from 1A (excluding lithium), 2A, 4B, 8B, 3A and 4A. For example, a molten spinel (MgAl2O4) synthesized at a temperature above 1,850°C using Al2O3 as an oxide of a 3A metal element and MgO as an oxide of a 2A metal element has low shrinkage, high thermal shock resistance and excellent corrosion resistance, and thus can suppress shrinkage and deformation of the protective layer during high-temperature calcination, but the description of this specification is not limited thereto. In addition, depending on the types of the second metal oxide and the third metal oxide, it is possible to prevent lithium from penetrating during calcination of the lithium-containing raw material and generating impurities.

[0141] In addition, the weight ratio of the second metal oxide to the third metal oxide in the protective layer can be 35 to 65:65 to 35, for example, 35:65, 37.5:62.5, 40:60, 42.5:57.5, 45:55, 47.5:52.5, 50:50, 52.5:47.5, 55:45, 57.5:42.5, 60:40, 62.5:37.5, 65:35, or a range between two values ​​thereof, but the present invention is not limited thereto. If the weight ratio of the second metal oxide to the third metal oxide satisfies the above range, the shrinkage or deformation rate of the protective layer can be easily controlled within a desired range.

[0142] On the other hand, according to another aspect of the present specification, there is provided a refractory sagger for calcining a precursor material, which is a refractory sagger including a main body having a space for loading the precursor material, wherein the main body includes a first metal oxide as a main material and further includes a second metal oxide not containing lithium.

[0143] In the refractory sagger as described above, the main body can suppress the formation of impurities due to lithium penetration by a mechanism similar to the above-mentioned protective layer. For example, the second metal oxide in the main body reacts with lithium to form a lithium composite oxide, thereby extending the life characteristics of the refractory sagger.

[0144] In the above-mentioned refractory crucible, the weight ratio of the above-mentioned first metal oxide and the above-mentioned second metal oxide can be 70-99:30-1, for example, it can be 70:30, 72.5:27.5, 75:25, 77.5:22.5, 80:20, 82.5:17.5, 85:15, 87.5:12.5, 90:10, 92.5:7.5, 95:5, 97.5:2.5, 99:1 or a range between two values, but the present invention is not limited thereto. If the above-mentioned range is met, the shrinkage and deformation of the refractory crucible can be minimized and the peeling phenomenon can be easily suppressed during repeated heat treatment reactions. In particular, when the weight ratio of the first metal oxide and the second metal oxide is in the range of 85-95:15-5, the above-mentioned characteristics may be more excellent, but this depends on the types of the first metal oxide and the second metal.

[0145] Preparation method of refractory sagger for calcining precursor materials

[0146] According to another aspect of the present specification, there is provided a method for preparing a refractory sagger for calcining a precursor material, comprising: step (a), preparing a molded body, wherein the molded body comprises a first metal oxide as a main material and is molded into a predetermined shape to include a space for loading the precursor material, and a protective composition comprising a second metal oxide that does not contain lithium is formed on at least a portion of the surface of the molded body; and step (b), heat treating the molded body at 500°C to 1,400°C.

[0147] Hereinafter, reference may be made to the above contents regarding the first metal oxide, the second metal oxide, the third metal oxide, and the lithium composite oxide.

[0148] Wherein, the molding in step (a) can utilize the known method used when preparing refractory sagger.For example, it can be formed into a shape with internal space by applying pressure by a press.For example, as the above-mentioned pressing method, after the refractory sagger main body composition and the protective composition are stacked, they are pressed, or after the refractory sagger main body composition is pressed, the protective composition is stacked, or after the refractory sagger main body composition is pressed, the protective composition is stacked and pressed, etc., and the method is not limited.

[0149] As an example, in the above step (a), the main composition including the first metal oxide as the main material is formed into a space for the precursor material to be loaded, and then the protective composition is located on at least a portion of the inner surface of the formed space. On the other hand, the protective composition can be located on the main composition and then molded to prepare a molded body in which the protective composition is located in the internal space. Alternatively, the molded body can also be prepared by locating the protective composition in the internal space of a manufactured refractory sagger.

[0150] In another example, a commercially available refractory sagger body may be used as the molded body, and the protective composition may be located on the inner surface of the refractory sagger.

[0151] On the other hand, in the above step (a), a molded body further comprising an adhesive composition comprising a first metal oxide and a second metal oxide not containing lithium between the main body and the above protective composition may be prepared. For the above adhesive composition, reference may be made to the description of the above adhesive layer.

[0152] In addition, the protective composition may further include a third metal oxide that does not contain lithium. In this regard, reference may be made to the above content regarding the inclusion of the third metal oxide that does not contain lithium in the protective layer.

[0153] That is, in the above step (a), a main body composition forming a main body and a protective composition forming a protective layer may be prepared to form separate layers, or a molded body may be prepared in which a main body composition region forming a main body, an adhesive composition region forming an adhesive layer, and a region including the protective composition forming a protective layer form separate layers, but the present invention is not limited thereto.

[0154] The heat treatment in the above step (b) is a process of calcining the main composition and the protective composition, which can be carried out at 500°C to 1,400°C, for example, at 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1,000°C, 1,050°C, 1,100°C, 1,150°C, 1,200°C, 1,250°C, 1,300°C, 1,350°C, 1,400°C or a range between two values.

[0155] In particular, if the heat treatment in the above step (b) is performed at a high temperature of 1,100°C or above, for example, at 1,100°C, 1,150°C, 1,200°C, 1,250°C, 1,300°C, 1,350°C, 1,400°C or a range between two values, a protective layer in the form of a dense body with low porosity can be easily formed.

[0156] When the high temperature heat treatment as described above is performed, the second metal oxide contained in the protective composition can be transformed into a dense body. On the other hand, when the refractory sagger including the second metal oxide and having undergone one or more precursor material calcination processes is subjected to high temperature heat treatment, a lithium composite oxide as a dense body can be formed in the protective layer. The characteristics of the refractory sagger including the protective layer as a dense body are as described above.

[0157] The heat treatment may be performed at a rate of 10°C / hour to 5,000°C / hour, for example, 10°C / hour, 25°C / hour, 50°C / hour, 75°C / hour, 100°C / hour, 125°C / hour, 150°C / hour, 200°C / hour, 250°C / hour, 300°C / hour, 350°C / hour, 400°C / hour, 450°C / hour, 500°C / hour, 750°C / hour, 1,000°C / hour, 1,250°C / hour, 1,500°C / hour, 1,750°C / hour, 2,000°C / hour, 2,250°C / hour, 2,500°C / hour. / hour, 3,000 ° C / hour, 3,500 ° C / hour, 4,000 ° C / hour, 4,500 ° C / hour, 5,000 ° C / hour or a range between two values ​​of the speed of temperature increase, keep 1 hour to 24 hours, for example, keep 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours or a range between two values ​​of time to achieve. Heat treatment temperature, heating rate and holding time can be changed according to the characteristics of the main composition and protective composition constituting the refractory sagger.

[0158] On the other hand, according to another aspect of the present specification, there is provided a method for preparing a refractory crucible for calcining a precursor material, comprising: step (a), preparing a molded body, wherein the molded body comprises a first metal oxide as a main material and a second metal oxide not containing lithium, and is molded into a predetermined shape to include a space for loading the precursor material; and step (b), heat treating the molded body at 500°C to 1,400°C.

[0159] According to the manufacturing method as described above, a refractory sagger can be manufactured, the main body of which suppresses the formation of impurities due to lithium penetration through a mechanism similar to that of the above-mentioned protective layer.

[0160] In the above preparation method, reference may be made to the above contents regarding the first metal oxide and the second metal oxide.

[0161] Hereinafter, the present invention will be described in more detail by way of examples. However, these examples are only intended to illustrate the present invention, and the scope of the present invention should not be construed as being limited by these examples.

[0162] Unless otherwise stated, the following examples were carried out at 25°C, normal pressure and air atmosphere.

[0163] Experimental Example 1

[0164] Raw materials of a refractory sagger in which cordierite, spinel, mullite and corundum are present in a molar ratio of 45:40:10:5, powdered molten spinel (MgAl2O4) and powdered manganese dioxide (MnO2) were prepared.

[0165] The compositions according to the weight ratios in Table 1 below were molded into a cylindrical shape having a diameter of 50 mm and then calcined at a temperature of 1,350° C. Among them, the samples of Experimental Examples D and E were molded to have a manganese oxide protective layer or a protective layer mixed with manganese oxide and molten spinel on the raw material layer and then calcined.

[0166] Table 1

[0167] Classification Experimental Example A Experimental Example B Experimental Example C Experimental Example D Experimental Example E raw materials 90 80 70 50 50 Manganese oxide 10 20 30 50 25 Fused spinel - - - - 25 Shrinkage characteristics ○ △ △ × ◎ Deformation characteristics ○ △ △ × ◎

[0168] In Table 1, the case where the material cannot be applied to a refractory sagger due to various properties is evaluated as ×, the case where the material is difficult to be applied to a refractory sagger is evaluated as △, the case where the material can be applied to a refractory sagger is evaluated as ○, and the case where the material is particularly excellent is evaluated as ◎.

[0169] Referring to the results of Table 1, when manganese oxide is mixed with a refractory sagger raw material so that the content of manganese oxide is less than 50 wt % or manganese oxide is mixed with molten spinel for use, shrinkage and deformation during high temperature calcination can be minimized.

[0170] Experimental Example 2

[0171] In Experimental Example 1, in order to confirm the reactivity between the samples of Experimental Example A and Experimental Example E having good shrinkage and deformation characteristics and lithium compounds, each sample was placed in an existing refractory sagger, and then the positive electrode active material precursor and lithium hydroxide were loaded so that the ratio of lithium to transition metal (Li / M) was 1.06. While maintaining the O2 atmosphere, the temperature was raised to 800°C and then calcined for 1 hour.

[0172] The above calcination process was repeated, and the last calcination number before the occurrence of spalling phenomenon that caused the performance of the positive electrode material as a final product to deteriorate was determined as the spalling resistance life and is shown in Table 2 below.

[0173] Table 2

[0174] Classification Refractory sagger Experimental Example A Experimental Example E Peeling resistance life Second time The third time More than the fifth time

[0175] From Table 2, it can be confirmed that the peeling resistance life can be improved by mixing manganese oxide in the refractory sagger (Experimental Example A) or forming a mixed layer of manganese oxide and molten spinel in the refractory sagger.

[0176] During the high-temperature calcination process, the refractory sagger and lithium may react, resulting in peeling. On the other hand, in the sample of the above-mentioned experimental example, lithium reacts to form a lithium composite oxide that can be used as a positive electrode material, thereby suppressing peeling. In addition, even if a part of it peels off, it is still a material that can be used as a positive electrode material, so the deterioration of the product can be minimized.

[0177] An example of a method for preparing a refractory sagger using the composition described above is as follows.

[0178] Comparative Example

[0179] A conventional refractory sagger was prepared in which cordierite, spinel, mullite, and corundum were present in a molar ratio of about 45:40:10:5.

[0180] Example 1

[0181] The mixture of Experimental Example A was pressed to prepare a square columnar molded body having an inner space for placing the calcined object. The molded body was heated to 1350° C. at 2° C. per minute, calcined for 1 hour, and cooled at room temperature to prepare a refractory sagger containing manganese oxide.

[0182] Example 2

[0183] The mixture of Experimental Example B was pressed to prepare a square columnar molded body having an inner space in which the calcined object could be placed. The molded body was heated to 1350° C. at 2° C. per minute, calcined for 1 hour, and cooled at room temperature to prepare a refractory sagger containing manganese oxide.

[0184] Example 3

[0185] The mixture of Experimental Example C was pressed to prepare a square columnar molded body having an inner space for placing the calcined object. The molded body was heated to 1350° C. at 2° C. per minute, calcined for 1 hour, and cooled at room temperature to prepare a refractory sagger containing manganese oxide.

[0186] Example 4

[0187] The manganese oxide used in the protective layer of (2) Experimental Example D was layered on the inner surface of an existing sagger, and then pressed. The sagger was heated to 1350°C at 5°C per minute, calcined for 1 hour, and cooled at room temperature to prepare a sagger having a protective layer formed on the inner surface of the body.

[0188] Example 5

[0189] A mixture of manganese oxide and molten spinel used in the protective layer of Experimental Example E was layered on the inner surface of an existing sagger, and then pressed. The mixture was heated to 1350° C. at 5° C. per minute, calcined for 1 hour, and cooled at room temperature to prepare a sagger having a protective layer formed on the inner surface of the main body.

[0190] Example 6

[0191] The raw materials used in the experimental example were pressed to prepare a square columnar molded body having an internal space in which a calcined object could be placed, and the molded body was formed so that a mixture layer of manganese oxide and molten spinel was formed in the lower part of the internal space as in the protective layer of Experimental Example E. The molded body was heated to 1350° C. at 2° C. per minute, calcined for 1 hour, and cooled at room temperature to prepare a refractory sagger formed with a protective layer.

[0192] Although the embodiments of the present specification are described above, those skilled in the art will understand that various modifications and changes can be made to the present specification by adding, modifying, deleting, increasing, etc., without departing from the scope of the ideas of the present specification as described in the claims, and these also fall within the scope of the rights of the present specification.

Claims

1. A refractory sagger for calcining a precursor material, comprising a main body having a space for loading the precursor material, wherein the main body comprises a first metal oxide as a main material, and a protective layer comprising a second metal oxide not containing lithium is formed on at least a portion of an inner surface of the main body constituting the space.

2. The refractory sagger for calcining precursor materials according to claim 1, characterized in that: The first metal oxide includes at least one selected from spinel, corundum, mullite, cordierite, spodumene, zircon, quartz, petalite, eucryptite, lithium disilicate, lithium metasilicate, forsterite, magnesium metasilicate, alumina and silicate.

3. The refractory sagger for calcining precursor materials according to claim 1, characterized in that: The second metal oxide reacts with lithium to form a lithium composite oxide capable of inserting and deinserting lithium.

4. The refractory sagger for calcining precursor materials according to claim 3, characterized in that: The lithium composite oxide is represented by the following chemical formula 1: [Chemical formula 1] Li w1 M x1 O 2-y1 X y1 (wherein, M is at least one selected from Al, Au, B, Ba, Ca, Ce, Co, Cr, Cu, Eu, F, Fe, Ga, Gd, Ge, Hf, K, Mg, Mn, Mo, Na, Nb, Nd, Ni, P, Pt, Si, Sm, Sn, Sr, Ta, Ti, V, W, Y, Zn and Zr, X is at least one selected from F, P and S, 0.5≤w1≤1.5, 0≤x1≤1, 0≤y1≤2).

5. The refractory sagger for calcining precursor materials according to claim 1, characterized in that: The second metal oxide is represented by the following chemical formula 2: [Chemical formula 2] M 1 x2 M 2 y2 O 2-z2 X z2 (Among them, M 1 is at least one selected from Ni, Co, Mn and Al, M 2 is at least one selected from Au, B, Ba, Ca, Ce, Cr, Cu, Eu, F, Fe, Ga, Gd, Ge, Hf, K, Mg, Mo, Na, Nb, Nd, P, Pt, Si, Sm, Sn, Sr, Ta, Ti, V, W, Y, Zn and Zr, X is at least one selected from F, P and S, 0 <x2≤1,0≤y2≤1,0≤z2≤2)。 6. The refractory sagger for calcining precursor materials according to claim 1, characterized in that: The content of the second metal oxide in the protective layer is 95 wt % or less.

7. The refractory sagger for calcining precursor materials according to claim 1, characterized in that: The difference in thermal expansion coefficient between the main body and the protective layer is 5×10 -6 / ℃ below.

8. The refractory sagger for calcining precursor materials according to claim 1, characterized in that: The protective layer has a porosity of 20 volume % or less.

9. The refractory sagger for calcining precursor materials according to claim 1, characterized in that: The invention also includes an adhesive layer, wherein the adhesive layer is located between the protective layer and the main body and contains the first metal oxide and the second metal oxide.

10. The refractory sagger for calcining precursor materials according to claim 9, characterized in that: In the adhesive layer, the second metal oxide may be present in an amount of 10 to 200 parts by weight based on 100 parts by weight of the first metal oxide.

11. The refractory sagger for calcining precursor materials according to claim 1, characterized in that: At least a portion of the protective layer further includes a third metal oxide that does not contain lithium.

12. The refractory sagger for calcining precursor materials according to claim 11, characterized in that: The third metal oxide includes at least one selected from (1) at least one oxide containing a metal element selected from 1A, 2A, 4B, 8B, 3A and 4A that do not include lithium; and (2) at least one composite oxide containing multiple oxides of a metal element selected from 1A, 2A, 4B, 8B, 3A and 4A that do not include lithium.

13. The refractory sagger for calcining precursor materials according to claim 11, characterized in that: In the protective layer, the weight ratio of the second metal oxide to the third metal oxide is 35-65:65-35 respectively.

14. A method for preparing a refractory sagger for calcining a precursor material, characterized in that: include: Step (a), preparing a molded body, wherein the molded body includes a first metal oxide as a main material and is molded into a predetermined shape to include a space for loading a precursor material, and a protective composition including a second metal oxide not containing lithium is contained on at least a portion of the surface of the molded body; and Step (b), heat treating the molded body at 500°C to 1,400°C.

15. The method for preparing a refractory sagger for calcining precursor materials according to claim 14, characterized in that: In the step (a), a bonding composition including a first metal oxide and a second metal oxide not containing lithium is further included between the main body of the molded body and the protective composition.

16. The method for preparing a refractory sagger for calcining precursor materials according to claim 14, characterized in that: The protective composition further comprises a third metal oxide that does not contain lithium.