KR101159102B1 - Furnace for Manufacture of Lithium-Metal Oxide and Process for Preparing the Same - Google Patents

Abstract

The present invention is a firing vessel used to produce a lithium transition metal oxide by firing reaction of a lithium precursor and a transition metal precursor, the inner surface of the firing vessel inhibits the reaction of the lithium melt and the firing vessel produced from the lithium precursor during the firing process And a coating product, or a reaction product of the lithium melt and the coating material, has a coefficient of thermal expansion of 3 x 10 ^-6 / 占 폚 or less that is different from the coefficient of thermal expansion of the baking vessel. Thereby providing a firing vessel composed of not being separated from the firing vessel in the firing process.

The firing vessel according to the present invention blocks the reaction between the molten lithium raw material and the inner surface of the vessel during the firing process, while suppressing the peeling of the reaction product by the reaction between the coating material itself or the coating material and the lithium melt from the vessel. Not only can damage of itself be prevented, but impurities are not incorporated into the container, thereby preventing the property heterogeneity of the lithium transition metal oxide, and solving the problem of subsequent process control due to the mixing of impurities. Therefore, the use of a homogeneous lithium transition metal oxide prepared using the firing vessel according to the present invention as a positive electrode active material, there is an advantage that can be produced a secondary battery of excellent battery performance.

Description

Firing vessel for manufacturing lithium metal oxide and method for manufacturing same {Furnace for Manufacture of Lithium-Metal Oxide and Process for Preparing the Same}

The present invention relates to a firing vessel for producing a lithium metal oxide and a method of manufacturing the same, and more particularly, to a firing vessel used for producing a lithium transition metal oxide by firing reaction of a lithium precursor and a transition metal precursor, the inner surface of the firing vessel Is coated with a material ('coating material') that suppresses the reaction between the lithium melt generated from the lithium precursor and the baking vessel during the firing process, and the coating material or the reaction product of the lithium melt and the coating substance is thermally expanded in the baking vessel. The difference from the coefficient has a coefficient of thermal expansion of 3 x 10 ^-6 / ° C. or less, thereby providing a firing container composed of not being separated from the firing vessel in the firing process.

As the development and demand for mobile devices increases, the demand for secondary batteries as energy sources is rapidly increasing. Among them, lithium secondary batteries with high energy density and voltage, long cycle life, and low self discharge rate It is commercially used and widely used.

Lithium-containing cobalt oxide (LiCoO ₂ ) is mainly used as a positive electrode active material of a lithium secondary battery. In addition, lithium-containing manganese oxides such as LiMnO _{2 having a} layered crystal structure and LiMn ₂ O _{4 having a} spinel crystal structure, and lithium-containing nickel oxide The use of (LiNiO ₂ ) is also contemplated.

Among the positive electrode active materials, LiCoO ₂ is used as a raw material due to its excellent physical properties such as cycle characteristics, although it is expensive due to a limited resource of cobalt. Lithium manganese oxides such as LiMnO ₂ and LiMn ₂ O ₄ have the advantage of using a resource-rich and environmentally friendly manganese as a raw material, attracting a lot of attention as a cathode active material that can replace LiCoO ₂ . In addition, lithium nickel-based oxides such as LiNiO ₂ have lower cost and higher discharge capacity than the cobalt-based or manganese-based oxides. Recently, researches on such nickel-based cathode active materials have been actively conducted to develop high capacity batteries. have.

Such a cathode material such as Li (Co, Mn, Ni) O _{2 is} , for example, firing a slurry in which a lithium-containing raw material (lithium precursor) and a transition metal-containing raw material (transition metal precursor) are mixed. It is prepared by putting it in a container (also called a crucible or sagger), heating it to a temperature of 200 to 1100 ° C. and baking it according to the type of raw materials, and then cooling it.

However, the amount of the raw material melt contained in the firing vessel after the firing process is generally reduced by about 0.5 to 30% with respect to the content of the initial raw material melt. This decrease is due to the reaction between the lithium raw material and the firing container component to form impurities, or the raw material permeating through the particle system and / or pores in the firing container.

That is, lithium sources such as LiOH and Li ₂ CO ₃ supported in the firing vessel react with Al ₂ O ₃ , SiO _2, etc. in the firing vessel during the heat treatment to form reaction by-products such as Li- (Al, Si) -O. The loss of lithium raw materials is caused by flowing into the particle system, pores, and the like of the baking vessel.

Moreover, the reaction by-products adhere to the baking vessel to form a reaction layer, and as the thickness thereof becomes thicker, some tend to peel off from the baking vessel. When the reactant separated in this manner is mixed in the positive electrode material, it acts as an impurity, causing a decrease in the quality of the positive electrode material. In addition, the surface of the inner wall of the baking container is damaged in the process of peeling the reaction layer, there is a problem that the life of the baking container is also shortened.

That is, the conventional baking container has a problem that its material is reactive with lithium, so that Li- (Al, Si) -O and the like are mixed in the positive electrode material in the form of impurities, and the baking container is polycrystalline and / or Or it is made of a material containing pores there is a problem that the content of the raw material melt contained in the baking container is reduced.

However, there is no technology capable of preventing many problems caused by using a conventional plastic container made of alumina, mullite, or the like when manufacturing a cathode material of lithium metal oxide.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art and the technical problems required from the past.

Specifically, an object of the present invention is a high quality positive electrode having homogeneous properties by preventing impurities such as Li- (Al, Si) -O from being formed by the reaction of a lithium melt and a firing vessel or preventing impurities from flowing into the firing vessel. It is to provide a baking container for producing a lithium transition metal oxide capable of producing ash.

Still another object of the present invention is to provide a baking container for producing a lithium transition metal oxide, which can prevent waste of lithium raw materials and damage to the baking container, thereby reducing manufacturing and process management costs.

A firing vessel according to the present invention for achieving this object is a firing vessel used to produce a lithium transition metal oxide by firing reaction of a lithium precursor and a transition metal precursor, the inner surface of the firing vessel from the lithium precursor in the firing process A coating material ('coating material') that suppresses the reaction of the resulting lithium melt with the firing vessel is coated, and the coating material or the reaction product of the lithium melt with the coating substance has a difference of 3 x 10 from the thermal expansion coefficient of the firing vessel. By having a coefficient of thermal expansion of ^-6 / ° C. or less, it is configured not to be separated from the firing vessel in the firing process.

The inventors of the present application have made various studies in order to improve the quality of the lithium transition metal oxide mainly used as a cathode material of a lithium secondary battery. Impurities such as (Al, Si) -O and the like have been found, and it has been found that the quality of the positive electrode material is lowered as they are mixed into the container.

Specifically, lithium hydroxide, lithium carbonate, or the like as a lithium precursor for the production of lithium transition metal oxide is melted at a calcination reaction temperature to form a lithium melt, and as a transition metal precursor, another raw material, transition metal hydroxide and transition metal carbonate. , Transition metal sulfates, transition metal nitrates, etc. also decompose at the firing reaction temperature to form transition metal oxides. Therefore, under normal firing reaction conditions, these lithium melts and transition metal oxides react in an oxidizing atmosphere to form lithium transition metal oxides, but relatively high lithium melt tends to react with the material of the baking vessel.

Therefore, the baking container of the present invention is coated on the inner surface of the material to inhibit the reaction between the lithium melt and the baking container produced from the lithium precursor during the baking process, the baking container itself and the lithium melt reacts in a high temperature baking process, Li The formation of impurities such as-(Al, Si) -O can be prevented.

Furthermore, in the present invention, since the difference in thermal expansion coefficient between the coating material itself or the reaction product of the lithium melt and the coating material is 3 × 10 ⁻⁶ / ° C. or less, the phenomenon of peeling from the inner wall of the container can be minimized. As a result, it is possible to prevent homogeneity and deterioration of characteristics of the lithium transition metal oxide due to the incorporation of impurities, and also to extend the life of the firing container itself.

In addition, the coating material may be prevented from penetrating into the grain boundaries or pores present in the firing vessel, thereby preventing waste of materials and lowering of the strength of the firing vessel.

The coating material, as defined above, is a material that inhibits the reaction between the lithium melt generated from the lithium precursor and the firing vessel during firing. This means that the coating material is applied to the inner wall of the container to block the possibility of contact between the container and the lithium melt.

As defined above, i) the coating material itself, or ii) the reaction product of the lithium melt and the coating material has a difference in thermal expansion coefficient between the firing vessel and 3 x 10 ⁻⁶ / ° C. or less. In general, the firing container is expanded by high temperature heat during firing and then contracts as it cools down at the end of the firing process. Accordingly, the coating layer ('coating layer') on the inner surface of the plastic container to which the coating material is applied also contracts and expands. If the difference between the thermal expansion coefficient of the plastic container and the thermal expansion coefficient of the coating layer is too large, the coating layer and the inner surface of the container may be The stress is generated at the interface, the coating layer is peeled off occurs. In this case, the reaction product of the coating material or the lithium melt is incorporated into the container, which not only acts as an impurity, but also damages the inner wall of the container while being peeled off, thereby causing a decrease in the life of the plastic container.

Therefore, in the present invention, the difference between the coefficient of thermal expansion of the coating material itself or the reaction product and the coefficient of thermal expansion of the firing vessel is 3 × 10 ⁻⁶ / ° C. or less, so that the thermodynamic behavior behaves similarly during contraction and expansion of the firing vessel. It is possible to minimize the delamination of the coating material or the reaction product.

In the present invention, the difference in coefficient of thermal expansion is 3 x 10 ^-6 / ℃ or less, preferably 2 x 10 ^-6 / ℃ or less. As described above, if the difference in thermal expansion coefficient is too large, stress may occur at the interface between the inner surface of the container and the coating layer, causing cracking, or the coating material itself or the reaction product forming the coating layer may be peeled off. On the other hand, the smaller the difference in the coefficient of thermal expansion may be reduced, and most ideally, the difference in coefficient of thermal expansion may be '0', but if less than 3 x 10 ^-6 / ℃, between the thin coating layer and the inner surface of the container Virtually no interfacial stress occurs.

In one preferred embodiment, the coating material, as a material that does not have a reactivity to the lithium melt, may have a thermal expansion coefficient difference within the above range. That is, when a non-reactive substance with lithium is used as a coating material, the reaction product is not formed by not reacting with the lithium melt, and the thermal expansion coefficient of the coating material is itself different from the thermal expansion coefficient of the plastic container. Since it is less than x 10 ⁻⁶ / ° C., peeling from the inner wall of the container can be prevented.

The material having no reactivity with the lithium melt should not only have low reactivity with the lithium melt, but is also coated on the inner wall of the firing container so that it has high heat resistance or fire resistance to withstand high heat, and has high strength or thermal shock resistance, and chemical erosion. Should be strong.

Preferred examples of such materials include MgO. The MgO is a white material having a melting point of about 2800 ° C., which is inert and excellent in fire resistance and thermal shock resistance. As experimentally confirmed by the present inventors, MgO has little reactivity with the lithium melt, and if it is coated on the inner surface of the baking vessel, it does not react with the lithium raw material, so that the generation of impurities can be fundamentally prevented.

In another preferred embodiment, the coating material is a material having reactivity with the lithium melt, the reaction product with the lithium melt may have a difference in coefficient of thermal expansion within the above range.

That is, the coating material may form a predetermined reaction product by reacting with the lithium melt, but this reaction product also has a difference from the thermal expansion coefficient of the firing vessel 3 x 10 ^-6 / ° C or less, substantially the inner wall of the vessel It does not peel off from. Thus, although the coating material is reactive with the lithium melt, it is possible to prevent its reaction product from entering the lithium transition metal oxide.

Coating materials having such a coefficient of thermal expansion are preferably alumina, silica, cordierite, aluminum titanate (Al ₂ TiO ₅ ), mullite (3Al ₂ O ₃ -2SiO ₂ ) It may be one containing one or more selected from the group consisting of, and mixtures thereof as a main component, particularly preferably cordierite may be used. Since the cordierite (2MgO? 2Al ₂ O ₂ ? 5SiO ₂ ) has a coefficient of thermal expansion of 1.7 to 3 × 10 ⁻⁶ / ° C., for example, when using a plastic container made of mullite, the difference in coefficient of thermal expansion is 3 ×. It is ^10-6 / degrees C or less.

The content of cordierite in the coating material is preferably contained at least 50% by weight. If the content of cordierite is less than 50% by weight, it may be difficult to control the difference in thermal expansion coefficient between the coating layer and the firing vessel to a level of 3 × 10 ⁻⁶ / ° C. or less. More preferred cordierite content is 80% by weight, particularly preferably at least 90% by weight.

In some cases, in addition to the cordierite, certain ceramic components may be added in consideration of the adhesion strength with the baking container, for example, although the thermal expansion coefficient is relatively higher than that of the cordierite. And ceramic components selected from the group consisting of MgO, ZrO ₂ , Al ₂ O ₃ , SiO ₂ , Si ₃ N _4, and SiC, which have excellent adhesion strength with the firing vessel. The content of the ceramic layer in the coating layer is preferably less than 50% by weight in consideration of the content of cordierite.

The firing vessel is not particularly limited as long as it has a predetermined heat resistance, thermal shock resistance, and mechanical strength, and for example, steel, alumina (A1 ₂ O ₃ ), quartz, fused silica (SiO ₂ ), silicon nitride, SiALON, Silicon carbide, aluminum nitride (AIN), magnesium oxide (MgO), zirconium oxide (zirconia), TiO ₂ , CaO, BeO, graphite, and mixtures thereof.

If the thermal expansion coefficient of the plastic container is too large, uniformity may occur in the container due to excessive expansion and contraction, so that the thermal expansion coefficient is in a range of 8 x 10 ^-6 / ° C or less, preferably 5 x 10 ^-6 / ° C or less. And alumina, mullite, quartz glass, and the like. The mullite (3Al ₂ O ₃ ~ 2SiO ₂ ) is a composite material of aluminum oxide and silicon dioxide, the coefficient of thermal expansion between quartz glass and A1 ₂ O ₃ , the coefficient of thermal expansion is 4.5 ~ 6 x 10 ^-6 / ℃ It is relatively small, has high thermal conductivity and strong thermal shock.

The size of the coating material included in the coating layer is not particularly limited, and may be a powder having a particle diameter of preferably about 100 μm or less in consideration of uniform application of the coating layer and bonding strength with the baking container.

The coating material may be applied to a portion of the inner surface, but is preferably applied to the entire inner surface, and the thickness of such coating layer may preferably be 0.1 to 10 mm. That is, when the thickness of the coating layer is too thin, it may be difficult to exert the reaction suppression effect of the desired lithium melt and the firing container for a long time, so that it may be cumbersome to use it by recoating every repeated use. On the contrary, when the thickness of the coating layer is too thick, it is not preferable because it may lead to waste of unnecessary materials and increase the manufacturing cost.

The lithium transition metal oxide may be preferably a cathode active material for a lithium secondary battery. Accordingly, the lithium transition metal oxide may be, for example, one or two or more selected from the group consisting of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, and mixed transition metal oxides thereof.

In a specific example, a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Li _{1 + x} Mn _{2 - x} O ₄ (Where x is 0 to 0.33), lithium manganese oxides such as LiMnO ₃ , LiMn ₂ O ₃ and LiMnO ₂ ; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ and LiFe ₃ O ₄ ; Ni-site type lithium nickel oxide represented by the formula LiNi _1-x M _x O ₂ , wherein M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 to 0.3; Formula LiMn _2-x M _x O ₂ (wherein M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ (wherein M = Fe, Co, Lithium manganese composite oxide represented by Ni, Cu, or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with alkaline earth metal ions; Li _{1 + z} Ni _1/3 Co _1/3 Mn _1/3 O ₂ , Li _{1 + z} Ni _0.4 Mn _0.4 Co _0.2 O _2, etc. Li _{1 + z} Ni _b Mn _c Co _{1- (b + c)} O Lithium nickel cobalt manganese composite oxide represented by ₂ (where 0 ≦ z ≦ 0.3, 0.1 ≦ b ≦ 0.8, 0.1 ≦ c ≦ 0.8, and b + c <1); Although these etc. are mentioned, it is not limited only to these.

The method for producing the baking container according to the present invention is not particularly limited and may be carried out by a known coating method.

In the first embodiment of the present invention, the firing vessel may be prepared by dissolving a coating material or a precursor powder thereof and an organic binder in a predetermined solvent to prepare a slurry, and applying and drying the slurry on the inner surface of the firing vessel. In some cases, a process of heat-treating the firing container may be further performed.

The slurry consists of a coating material, an organic binder, and a solvent, as described above.

The solvent is for dispersing or dissolving the lithium non-reactive material or its precursor powder and the organic binder, and may vary according to its type. Preferably, the solvent is selected from the group consisting of alcohol solvents, ketone solvents, and ester solvents. It may be one or more than one selected. In addition, the solvent may be used by mixing two or more kinds.

The alcohol solvent is, for example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, iso-butyl alcohol, 1-pentanol, 2-pentanol, 2-methyl-2- Pentanol, iso-amyl alcohol, etc. are mentioned. In addition, the alcohol solvent includes an alkoxy alcohol, that is, an alcohol including an ether group. Examples thereof include 2-methoxyethanol, 1-methoxy-2-propanol, and the like, but are not limited thereto. no.

As said ketone solvent, acetone, ethyl methyl ketone, methyl isobutyl ketone, etc. are mentioned, for example.

The ester solvents are, for example, ethyl acetate, propyl acetate, n-butyl acetate, sec-butyl acetate, tert-butyl acetate, isobutyl acetate, n-amyl acetate, sec-amyl acetate, tert-amyl acetate, and iso-amyl acetate and the like.

In addition, hydrocarbon solvents such as toluene, xylene, hexane, and cyclohexane may be used, and are not particularly limited.

The organic binder is a component for exerting the bonding strength between the coating material or its precursor powders and the adhesion to the inner wall of the baking vessel in the application of the slurry, and is not particularly limited as long as it can perform such a role. As such an example, it may preferably be one or two or more selected from the group consisting of polyethylene glycol, polyvinyl alcohol, polycarbonate, carboxymethyl cellulose and epoxy.

As the method for applying the slurry, for example, a spray method, a dipping method, or the like may be used.

The heat treatment process may be performed as a separate step, but may also be performed together in the sintering process for the production of the positive electrode active material using a firing vessel in the coating and dried state for the coating slurry. This heat treatment decomposes the binder component in the coating layer and calcines the coating material, so that the heat treatment is performed at least at a temperature higher than the thermal decomposition temperature of the organic binder. However, if the heat treatment temperature is too low, the coating layer is not baked on the surface of the baking container, the bulk density and crystallinity is lowered, it is difficult to maintain a stable form, the bonding layer of the coating layer and the baking container can be easily peeled off so It is therefore undesirable because the inner wall of the firing vessel may also be damaged.

In addition, if the heat treatment time is too short, it is difficult to obtain the desired level of coating layer, and if too long, the overall production efficiency may be lowered, which is not preferable.

In a specific example in consideration of this, when the coating material is cordierite, the heat treatment of the baking vessel is preferably performed for 0.5 to 4 hours at a temperature of 400 to 1500 ℃.

In addition, in the second embodiment of the present invention, the firing vessel is prepared by dissolving a coating material or a precursor powder thereof and an inorganic binder in a predetermined reaction solvent to prepare a slurry, applying the slurry to the inner surface of the firing vessel, and then drying the slurry. It can be prepared by a method comprising the step of forming a powder coating layer in which the coating material is bonded to the inner surface of the baking container by an inorganic binder.

This method is characterized in that the inorganic binder is included in the slurry, so that a separate heat treatment process is not necessary.

The inorganic binder is to improve the applicability and adhesion of the slurry to the inner wall of the firing vessel, for example, cement, calcium sulfate, gypsum, mud, clay, sodium silicate And silicic acid-based binders such as alumina silicate and calcium silicate, and preferably one or two or more selected from the group consisting of SiO ₂ , Al ₂ O ₃ , CaO, and cement. The reaction solvent may be water, alcohol, or a mixture thereof.

The drying process is a step for evaporating the remaining solvent after the reaction and fixing the inorganic binder, the drying temperature may vary depending on the type of solvent and inorganic binder used, preferably at a temperature of 20 to 500 ℃ It is preferable.

The present invention is also a lithium secondary powder characterized in that the lithium precursor powder and the transition metal precursor powder is put in a firing vessel coated with the coating material on the inner surface and calcined at a temperature of 400 to 1100 ℃ to produce a calcined body of lithium transition metal oxide. Provided is a method for producing a battery positive electrode material.

The cathode material manufactured in this manner does not contain impurities such as LiAlO ₂ , LiSiO, LiAlSiO _4, and thus exhibits homogeneous characteristics, and thus the secondary battery including the same has excellent performance. In addition, the manufacturing method according to the present invention has the advantage that can be prevented because the loss of the lithium raw material that occurred in the conventional manufacturing process of the positive electrode material can be reduced.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are provided to illustrate the present invention, and the scope of the present invention is not limited thereto.

Example 1

On the inner surface of a mullite firing vessel having a diameter of 200 mm and a depth of 150 mm, a slurry containing 25 wt% cordierite powder, 0.5 wt% PVA as an organic binder, and 74.5 wt% ethanol as a solvent was coated and fired at 1000 ° C. To prepare a fired container in which the cordierite coating layer was formed. Then, 20.5% by weight of LiOH and 79.5% by weight of transition metal precursor cobalt hydroxide were placed in a baking vessel and calcined at 1000 ° C. to prepare LiCoO ₂ . The amount of aluminum and silicon in the prepared LiCoO ₂ was analyzed. The obtained values were below the detection limit as Al <0.01% and Si <0.01%, respectively. In addition, it was confirmed that the inner surface of the baking container was not damaged at all.

[Example 2]

On the inner surface of the baking vessel, a slurry containing 60% by weight cordierite powder, 25% by weight SiO ₂ -Al ₂ O ₃ -CaO as an inorganic binder, and 15% by weight water as a reaction solvent was coated and dried at 100 ° C. LiCoO ₂ was manufactured in the same manner as in Example 1, except that a fired container in which a cordierite coating layer was formed was manufactured. The amount of Al and Si in the prepared LiCoO ₂ was analyzed. The obtained values were below the detection limit as Al <0.01% and Si <0.01%, respectively. In addition, it was confirmed that the inner surface of the baking container was not damaged at all.

Comparative Example 1

LiCoO ₂ was manufactured in the same manner as in Example 1, except that cordierite was not coated on the inner surface of the alumina calcining container. The amount of Al of the prepared LiCoO ₂ was 1%, the amount of Si was 0.1%, and it was confirmed that a fired portion was partially present on the inner surface of the firing vessel. In addition, it was confirmed that when repeated use, a dark reactant layer is formed and is easily peeled off.

As described above, the firing vessel according to the present invention is coated on the inner surface with a coating material for inhibiting the reaction between the lithium melt and the firing vessel, the reaction between the molten lithium precursor and the surface of the vessel is blocked during the firing process, Since the difference in the thermal expansion coefficient of the coating material or the reaction product of the lithium melt and the coating material and the firing container is small, it is possible to prevent the coating layer from being peeled off, thereby preventing the impurities from entering the container and damaging the container itself. Therefore, there is an advantage that can produce a lithium transition metal oxide fired body of homogeneous properties.

Those skilled in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above contents.

Claims (19)

A firing vessel used to produce a lithium transition metal oxide by firing reaction of a lithium precursor and a transition metal precursor, wherein an inner surface of the firing vessel has a material for inhibiting the reaction between the lithium melt produced from the lithium precursor and the firing vessel ( 'Coating material'), and the coating material, or the reaction product of the lithium melt and the coating material, has a coefficient of thermal expansion of 3 x 10 ^-6 / ° C or less, which is different from that of the baking vessel. A firing vessel, wherein the coating material does not separate from the firing vessel in a firing process and the coating material comprises at least 50% by weight cordierite. The fired container of claim 1, wherein the coating material is a material that is not reactive to a lithium melt and has a coefficient of thermal expansion within the above range. The firing vessel of claim 1, wherein the coating material is a material having a reactivity with respect to the lithium melt, and the reaction product with the lithium melt has a difference in coefficient of thermal expansion within the above range. The fired container according to claim 1, wherein the thermal expansion coefficient difference is 2 × 10 ⁻⁶ / ° C. or less. delete delete The method of claim 1, wherein the coating material comprises less than 50% by weight of one or more ceramic components selected from the group consisting of MgO, ZrO ₂ , Al ₂ O ₃ , SiO ₂ , Si ₃ N ₄ and SiC The firing container characterized by the above-mentioned. The firing vessel of claim 1, wherein the coating material is coated to a thickness of 0.1 to 10 mm. The firing vessel of claim 1, wherein the firing vessel is made of one or more materials selected from the group consisting of alumina, silica, and mullite. The baking container according to claim 1, wherein the lithium transition metal oxide is a cathode active material for a lithium secondary battery. The method of claim 10, wherein the lithium transition metal oxide is one or more selected from the group consisting of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, mixed transition metal oxide and lithium nickel cobalt manganese composite oxide. Firing container. 12. A process for producing a firing vessel according to any one of claims 1 to 4 and 7 to 11, comprising: a substance ('coating substance') that inhibits the reaction between a lithium melt produced from a lithium precursor and the firing vessel; Or dissolving a precursor powder thereof and an organic binder in a predetermined solvent to prepare a slurry, and applying and drying the slurry on the inner surface of the baking container, wherein the coating material contains at least 50% by weight of cordierite. Manufacturing method characterized in that. The method of claim 12, wherein the solvent is one or two or more selected from the group consisting of an alcohol solvent, a ketone solvent, and an ester solvent. The method of claim 12, wherein the organic binder is one or more selected from the group consisting of polyethylene glycol, polyvinyl alcohol, polycarbonate, carboxymethyl cellulose, and epoxy. The method according to claim 12, further comprising performing a heat treatment process after drying the slurry. 12. A process for producing a firing vessel according to any one of claims 1 to 4 and 7 to 11, comprising: a substance ('coating substance') that inhibits the reaction between a lithium melt produced from a lithium precursor and the firing vessel; Or a powder prepared by dissolving the precursor powder and the inorganic binder thereof in a predetermined reaction solvent, applying the slurry to the inner surface of the baking container, and drying the powder to which the coating material is bound to the inner surface of the baking container by the inorganic binder. Forming a coating layer, wherein the coating material comprises at least 50% by weight of cordierite. The method of claim 16, wherein the inorganic binder is one or two or more selected from the group consisting of SiO ₂ , Al ₂ O ₃ , CaO, and cement. The method of claim 16, wherein the reaction solvent is water, an alcohol, or a mixture thereof. 12. The lithium firing powder and the transition metal precursor powder are placed in a firing container according to any one of claims 1 to 4 and 7 to 11 and calcined at a temperature of 400 to 1100 ° C. Method for producing a cathode material for a lithium secondary battery, characterized in that the manufacturing.